阅读说明：本技术 粒子束检查装置 (Particle beam inspection apparatus ) 是由 J·G·戈森 陈德育 D·H·C·范班宁 E·C·卡迪杰克 M·P·C·范赫尤门 王二恒 于 2019-07-11 设计创作，主要内容包括：公开了一种改进的粒子束检查装置,并且更具体地,公开了一种包括改进的装载锁定单元的粒子束检查装置。一种改进的装载锁定系统可以包括被配置为支撑晶片的多个支撑结构和包括被配置为调节晶片的温度的传热元件的调节板。装载锁定系统还可以包括被配置为在调节板与晶片之间提供气体的排气孔和被配置为辅助对传热元件的控制的控制器。(An improved particle beam inspection apparatus is disclosed, and more particularly, a particle beam inspection apparatus including an improved load lock unit is disclosed. An improved load lock system may include a plurality of support structures configured to support wafers and a conditioning plate including a heat transfer element configured to adjust a temperature of the wafers. The load lock system may further include a vent configured to provide gas between the conditioning plate and the wafer and a controller configured to assist in control of the heat transfer element.)

1. A load lock system, comprising:

a plurality of support structures configured to support a wafer;

a first regulating plate including a first heat transfer element configured to regulate a temperature of the wafer;

a first exhaust hole configured to provide a gas between the first conditioning plate and the wafer; and

a controller comprising a processor and a memory, the controller configured to facilitate control of the first heat transfer element.

2. The load lock system of claim 1, wherein the first modulation plate is positioned above the wafer.

3. The load lock system of claim 1, wherein the first adjustment plate is positioned below the wafer.

4. The load lock system of claim 1, wherein the plurality of support structures are coupled to the first modulation plate.

5. The load lock system of claim 1, wherein the first venting aperture is attached to the first modulation plate.

6. The load lock system of claim 1, wherein the controller is further configured to assist in control of the first heat transfer element based on a temperature of a wafer stage.

7. The load lock system of claim 1, further comprising: a second conditioning plate including a second heat transfer element configured to condition a temperature of the wafer.

8. The load lock system of claim 7, wherein the plurality of support structures configured to support a wafer are positioned between the first and second modulation plates.

9. The load lock system of claim 7, further comprising a second vent configured to provide a portion of the gas between the second conditioning plate and the wafer.

10. The load lock system of claim 7, wherein the controller is further configured to assist in controlling the second heat transfer element based on a temperature of the wafer stage.

11. The load lock system of claim 1, further comprising a load lock chamber configured to enclose the first conditioning plate, the plurality of support structures, and the wafer.

12. The load lock system of claim 11, further comprising a second vacuum pump connected to the load lock chamber.

13. The load lock system of claim 12, wherein the controller is further configured to:

enabling the first vacuum pump to reduce the pressure inside the load lock chamber to a first pressure level, an

Enabling the second vacuum pump to reduce a pressure inside the load lock chamber to a second pressure level, wherein the second pressure level is lower than the first pressure level.

14. The loadlock system of claim 13, wherein the second vacuum pump shares an exhaust path with a third vacuum pump connected to a main chamber.

15. A non-transitory computer-readable medium comprising a set of instructions executable by one or more processors of a controller to cause the controller to perform a method of performing thermal conditioning of a wafer, the method comprising:

instructing a first vacuum pump to evacuate a load lock chamber of a load lock system after a wafer is loaded into the load lock chamber;

instructing a gas supply to provide gas to the load lock chamber; and

instructing a first heat transfer element in a first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer through the gas.

Technical Field

Embodiments provided herein disclose a particle beam inspection apparatus, and more particularly, a particle beam inspection apparatus including an improved load lock unit.

Background

When manufacturing semiconductor Integrated Circuit (IC) chips, pattern defects and/or unwanted particles (residues) inevitably appear on the wafer and/or the mask during the manufacturing process, thereby greatly reducing the yield. For example, for patterns with smaller critical feature sizes that have been adopted to meet the more advanced performance requirements of IC chips, unwanted particles can be troublesome.

Pattern inspection tools with charged particle beams have been used to detect defects or unwanted particles. These tools typically employ a Scanning Electron Microscope (SEM). In the SEM, a primary electron beam having a relatively high energy is decelerated so as to land on a sample at a relatively low landing energy, and focused to form a detection spot thereon. As a result of this focused primary electron detection spot, secondary electrons will be generated from the surface. The pattern inspection tool may acquire an image of the sample surface by scanning the probe spot over the sample surface and collecting the secondary electrons.

During operation of the inspection tool, the wafer is typically held by a wafer stage. The inspection tool may comprise a wafer positioning device for positioning the wafer stage and the wafer relative to the electron beam. This can be used to locate a target area (i.e., an area to be inspected) on the wafer within the working range of the electron beam.

Disclosure of Invention

Embodiments provided herein disclose a particle beam inspection apparatus, and more particularly, a particle beam inspection apparatus including an improved load lock unit. In some embodiments, an improved load lock system includes a plurality of support structures configured to support a wafer and a first conditioning plate. The first regulating plate includes a first heat transfer element configured to regulate a temperature of the wafer. The improved load lock system also includes a first vent configured to provide a gas between the first conditioning plate and the wafer. In addition, the improved load lock system includes a controller including a processor and a memory. The controller is configured to assist in control of the first heat transfer element.

In some embodiments, a method of thermal conditioning of a wafer in a load lock system is provided. The method includes loading a wafer into a load lock chamber of a load lock system and evacuating the load lock chamber. The method also includes providing a gas to the load lock chamber. The method also includes enabling a first heat transfer element in the first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer through the gas.

In some embodiments, a non-transitory computer-readable medium is provided. The non-transitory computer readable medium includes a set of instructions executable by one or more processors of a controller to cause the controller to perform a method of performing thermal conditioning of a wafer. The method includes instructing a vacuum pump to evacuate a load lock chamber of the load lock system after the wafer is loaded into the load lock chamber. The method also includes instructing a gas supply to provide gas to the load lock chamber and instructing a first heat transfer element in the first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer through the gas.

In some embodiments, a method of evacuating a load lock chamber is provided. The method comprises the following steps: pumping gas out of the load lock chamber with a first vacuum pump configured to exhaust gas to a first exhaust system; and pumping the gas out of the load lock chamber with a second vacuum pump configured to exhaust the gas to a second exhaust system.

Other advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which certain embodiments of the invention are set forth by way of illustration and example.

Drawings

The above and other aspects of the present disclosure will become more apparent by describing exemplary embodiments in conjunction with the attached drawings.

Fig. 1A is a schematic diagram illustrating an exemplary charged particle beam inspection system, according to an embodiment of the present disclosure.

Fig. 1B is a schematic diagram illustrating an exemplary wafer loading sequence in the charged particle beam inspection system of fig. 1A, in accordance with an embodiment of the present disclosure.

FIG. 1C is a schematic diagram illustrating exemplary wafer deformation effects in a charged particle beam inspection system.

FIG. 2 is an exemplary graph illustrating wafer temperature over time in a charged particle beam inspection system.

Fig. 3A and 3B are schematic diagrams illustrating an exemplary load lock system according to an embodiment of the present disclosure.

Fig. 3C is an exemplary graph illustrating wafer temperature over time during wafer temperature conditioning in a load lock system according to an embodiment of the present disclosure.

Fig. 3D and 3E are schematic diagrams illustrating an exemplary load lock system according to an embodiment of the present disclosure.

Fig. 3F is an exemplary graph illustrating changes in heat transfer efficiency with respect to air pressure levels in a load lock system according to an embodiment of the present disclosure.

FIG. 4 is a schematic diagram of an exemplary prealigner in an Equipment Front End Module (EFEM) in accordance with an embodiment of the present disclosure.

Fig. 5 is a schematic diagram illustrating an exemplary configuration of a wafer conditioning system according to an embodiment of the present disclosure.

Fig. 6A is a schematic diagram illustrating an exemplary configuration of a wafer conditioning system according to an embodiment of the present disclosure.

Fig. 6B is a schematic diagram illustrating an exemplary support structure of the wafer conditioning system of fig. 6A, in accordance with an embodiment of the present disclosure.

Fig. 6C is an exemplary graph illustrating temperature variation during conditioning in a wafer conditioning system according to an embodiment of the present disclosure.

Figure 6D is a schematic diagram illustrating an exemplary control circuit of a wafer conditioning system according to an embodiment of the present disclosure.

Fig. 7 is a flow chart illustrating an exemplary method for regulating wafer temperature in accordance with an embodiment of the present disclosure.

Fig. 8A and 8B are schematic diagrams illustrating an exemplary charged particle beam inspection system having a vacuum pump system, according to an embodiment of the present disclosure.

Fig. 9 is an exemplary graph illustrating pressure variations in a main chamber of a charged particle beam inspection system according to an embodiment of the present disclosure.

FIG. 10 is a schematic diagram illustrating an exemplary charged particle beam inspection system with a vacuum pump system, according to an embodiment of the present disclosure.

FIG. 11 is a flow chart illustrating an exemplary method for controlling the vacuum level of the load lock chamber of the charged particle beam inspection system of FIG. 10, according to an embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, in which like numerals refer to the same or similar elements throughout the different views unless otherwise specified. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the invention. Rather, they are merely examples of apparatus and methods consistent with aspects of the invention set forth in the claims below.

Electronic devices are made up of circuits formed on a silicon wafer called a substrate. Many circuits may be formed together on the same silicon die and are referred to as integrated circuits or ICs. The size of these circuits has been greatly reduced so that more of them can be mounted on a substrate. For example, an IC chip in a smart phone may be as small as a thumb nail, but may include over 20 hundred million transistors, each transistor having a size less than 1/1000 for a human hair size.

Manufacturing these extremely small ICs is a complex, time consuming and expensive process, typically involving hundreds of individual steps. Even an error in one step may result in a defect in the finished IC, rendering it useless. It is therefore an object of the manufacturing process to avoid such defects in order to maximize the number of functional ICs manufactured in the process, i.e. to improve the overall yield of the process.

One component that improves yield is monitoring the chip fabrication process to ensure that it produces a sufficient number of functional integrated circuits. One way to monitor this process is to inspect the chip circuit structure at various stages of its formation. The examination may be performed using a Scanning Electron Microscope (SEM). SEM can be used to image these very small structures, in effect "photographing" the structure. The image may be used to determine whether the structure is formed correctly and in the correct location. If the structure is defective, the process can be adjusted so that the defect is less likely to occur again.

While high process yields are desirable in an IC chip manufacturing facility, it is also important to maintain high wafer throughput (defined as the number of wafers processed per hour). High process yields and high wafer throughput can be affected by the presence of defects, particularly if an operator intervenes to view the defects. Therefore, high throughput detection and identification of micro-and nano-scale defects by inspection tools (such as SEM) is crucial to maintaining high yield and low cost.

One aspect of the present disclosure includes an improved load lock system that increases throughput of the overall inspection system. The improved load lock system prepares wafers in a manner that speeds up the inspection process as compared to conventional particle beam inspection systems. For example, an operator who is inspecting a wafer using a conventional particle beam inspection system needs to wait for the wafer temperature to stabilize before starting the inspection. This temperature stabilization is required because the wafer changes dimensions with temperature changes (which can cause components on the wafer to move as the wafer expands or contracts). For example, FIG. 1C shows that as wafer 160 expands due to temperature changes, elements 180, 182, 184, and 186 may move to new locations 170, 172, 174, and 178. Also, when the precision of inspecting a wafer is on the order of nanometers, such positional variation is large. Therefore, in order for the operator to accurately position and inspect the components on the wafer, the operator must wait until the wafer temperature stabilizes.

The improved load lock system conditions the wafer so that its temperature approaches that of the inspection wafer station that will hold the wafer. The improved load lock system may condition the wafer by including a conditioning plate that transfers heat to or from the wafer before the wafer is placed on the wafer stage. By conditioning the wafer before it is placed on the wafer table, inspection can be started with less delay. Thus, the operator can inspect more wafers in a given time period, thereby increasing throughput.

The relative dimensions of components in the figures may be exaggerated for clarity. In the following description of the drawings, the same or similar reference numerals refer to the same or similar parts or entities and only the differences with respect to individual embodiments are described. As used herein, unless otherwise expressly specified, the term "or" encompasses all possible combinations unless not feasible. For example, if a claim element may include a or B, the element may include a or B or a and B unless explicitly stated otherwise or not possible. As a second example, if a claim element may include A, B or C, the element may include a or B or C or a and B or a and C or B and C or a and B and C unless explicitly stated otherwise or not possible.

Referring now to fig. 1A, fig. 1A is a schematic diagram illustrating an exemplary charged particle beam inspection system 100, according to an embodiment of the present disclosure. As shown in fig. 1A, the charged particle beam inspection system 100 includes a main chamber 10, a load lock chamber 20, an electron beam tool 40, and an Equipment Front End Module (EFEM) 30. The electron beam tool 40 is located within the main chamber 10. Although the description and drawings refer to electron beams, it should be understood that the embodiments are not intended to limit the invention to specific charged particles. It should also be understood that the e-beam tool 40 may be a single beam tool utilizing a single electron beam or a multi-beam tool utilizing multiple electron beams.

The EFEM30 includes a first load port 30a and a second load port 30 b. The EFEM30 may include other load ports. The first and second load ports 30a, 30b may, for example, accommodate a Front Opening Unified Pod (FOUP) for a wafer (e.g., a semiconductor wafer or a wafer made of other materials) or a sample to be inspected (wafer and sample are hereinafter collectively referred to as "wafer"). One or more robotic arms in the EFEM30 (e.g., the robotic arm shown in FIG. 1B) transport the wafer to the load lock chamber 20.

The load lock chamber 20 may be attached to the main chamber 10 by a gate valve between the chambers (e.g., gate valve 26 of fig. 1B). The load lock chamber 20 may include a sample holder (not shown) that may hold one or more wafers. The load lock chamber 20 may also include a mechanical transfer device (e.g., the robotic arm 12 of fig. 1B) to move the wafer into and out of the main chamber 10. The load lock chamber 20 may be connected to a load lock vacuum pump system (not shown) that removes gas molecules in the load lock chamber 20 to a first pressure below atmospheric pressure. After the first pressure is reached, one or more robotic arms (as shown in FIG. 1B) transport the wafer from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pumping system (not shown) that removes gas molecules from the main chamber 10 to reach a second pressure lower than the first pressure. After the second pressure is reached, the wafer is inspected by the electron beam tool 40.

The controller 50 is electrically connected to the electron beam tool 40. The controller 50 may be a computer configured to perform various controls of the charged particle beam inspection system 100. Although the controller 50 is shown in FIG. 1A as being external to the structure including the main chamber 10, the load lock chamber 20, and the EFEM30, it should be understood that the controller 50 may be part of the structure. Although the present disclosure provides an example of a main chamber 10 housing an electron beam inspection tool, it should be noted that aspects of the present disclosure are not limited in their broadest sense to a chamber housing an electron beam inspection tool. Rather, it should be understood that the foregoing principles may also be applied to other tools operating at a second pressure.

Referring now to fig. 1B, fig. 1B is a schematic diagram illustrating an exemplary wafer loading sequence in the charged particle beam inspection system 100 of fig. 1A, according to an embodiment of the present disclosure. In some embodiments, the charged particle beam inspection system 100 may include a robotic arm 11 located in the EFEM30 and a robotic arm 12 located in the main chamber 10. In some embodiments, the EFEM30 may also include a prealigner 60 configured to precisely position the wafer prior to transporting the wafer to the load lock chamber 20.

In some embodiments, the first load port 30a and the second load port 30b may receive, for example, a Front Opening Unified Pod (FOUP) containing wafers. The robotic arm 11 in the EFEM30 may transport the wafer from any load port to the prealigner 60 to assist in positioning. The prealigner 60 may use mechanical or optical alignment methods to position the wafer. After pre-alignment, the robotic arm 11 may transport the wafer to the load lock chamber 20.

After the wafer is transferred to the load lock chamber 20, a load lock vacuum pump (not shown) may remove gas molecules in the load lock chamber 20 to a first pressure below atmospheric pressure. After the first pressure is reached, the robotic arm 12 may transport the wafer from the load lock chamber 20 to the wafer stage 80 of the e-beam tool 40 in the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pumping system (not shown) that removes gas molecules from the main chamber 10 to reach a second pressure lower than the first pressure. After the second pressure is reached, the wafer may be inspected by an electron beam tool.

In some embodiments, the main chamber 10 may include a docking station 70 configured to temporarily store wafers prior to inspection. For example, when inspection of the first wafer is completed, the first wafer may be unloaded from the wafer stage 80, and then the robot arm 12 may transport the second wafer from the parking station 70 to the wafer stage 80. Thereafter, the robotic arm 12 may transport the third wafer from the load lock chamber 20 to the docking station 70 to temporarily store the third wafer until inspection of the second wafer is complete.

Referring now to FIG. 2, FIG. 2 is an exemplary graph illustrating wafer temperature of a charged particle beam inspection system over time. The vertical axis represents temperature change, and the horizontal axis represents elapsed time. The figure shows that the wafer temperature may change over time as the wafer is processed through a multi-stage wafer loading sequence. According to the exemplary data shown in fig. 2, when a FOUP accommodating a wafer to be inspected is loaded into the first load port 30a or the second load port 30b, the temperature of the wafer is about 22.5 degrees.

After the wafer is transferred to the load lock chamber, the wafer temperature drops sharply almost once when the load lock chamber is evacuated to vacuum. This sudden temperature drop may be referred to as a pump-down effect. Subsequently, the wafer and the wafer stage may be at different temperatures when the wafer is transported and loaded onto the wafer stage. For example, the graph in fig. 2 may show that when a wafer is loaded into the wafer stage (denoted as 210 in fig. 2), there may be a temperature difference of about 2.5 degrees between the wafer located in the load lock chamber (denoted as 220 in fig. 2) and the wafer stage located in the main chamber (denoted as 230 in fig. 2). In this case, heat transfer may occur between the wafer and the wafer stage, thereby causing deformation (e.g., thermal expansion as shown in fig. 1C) of the wafer (or the wafer stage). When the wafer stage or the wafer undergoes thermal deformation, inspection of the target area may not be performed or accuracy may be degraded. Thus, to perform a more accurate inspection, the system waits for a relatively long time until the wafer temperature stabilizes before inspection can begin. This waiting time reduces the throughput of the inspection system.

An example of a wafer stage for faster temperature stabilization may be found in european patent application No. ep18174642.1 entitled "part BEAM APPARATUS", filed on 28/5/2018, the entire contents of which are incorporated herein by reference. Another way to cope with such long settling times is to regulate the wafer temperature by pre-heating or pre-cooling the wafer to match the temperature of the wafer table before the wafer is loaded onto the wafer table. In such embodiments, the conditioning step may be performed while a preceding wafer is inspected on the wafer stage, and thus, the overall throughput of the inspection system may be increased as compared to a system in which conditioning is performed after a wafer is loaded onto the wafer stage.

In some embodiments, the temperature adjustment function may be implemented in a load lock chamber, which may provide for increased throughput and future flexibility. If temperature adjustment of the wafer is performed in the load lock chamber, the next wafer in the line may be loaded into the load lock chamber while the previous wafer is being inspected. In some examples, it is calculated that in this sequence, the maximum available time for conditioning the wafer will be about 5-10 minutes, which is about the shortest inspection time for the wafer in the shortest user case in the current range. Therefore, one of the advantages of performing the wafer temperature adjustment in the load lock chamber is that the wafer adjustment time can be hidden under the inspection time since the adjustment of the next wafer and the inspection of the current wafer can be performed simultaneously. This may improve the overall yield of the particle beam inspection system.

In some embodiments, a charged particle beam inspection system (such as charged particle beam inspection system 100 of fig. 1B) may include a coarse temperature adjuster and a fine temperature adjuster. For example, a prealigner (such as prealigner 60 of fig. 1B) may include a coarse adjuster while a load lock chamber (such as load lock chamber 20) includes a fine adjuster. The coarse adjuster may make adjustments to the wafer for a coarse offset, e.g., from 2 degrees to 500mK, while the fine adjuster may make fine offset adjustments to the wafer, e.g., from 500mK to 50 mK.

Referring now to fig. 3A, fig. 3A illustrates an exemplary load lock system 300a, according to an embodiment of the present disclosure. In some embodiments, load lock system 300a may include a plurality of support structures 325 and conditioning plates 315 configured to transfer heat to wafer 320. In other embodiments, the conditioning plate 315 may be configured to additionally or alternatively transfer heat from the wafer 320. A support structure 325 coupled to the conditioning plate 315 may support the wafer 320 such that a space exists between the wafer 320 and the conditioning plate 315. However, it is understood that more efficient heat transfer may be achieved as the wafer 320 is positioned closer to the conditioning plate 315, and in some embodiments it may be desirable to have sufficient distance between the wafer 320 and the conditioning plate 315 to provide space for the robotic arm to lift or transport the wafer 320. In some embodiments, the distance between the wafer 320 and the adjustment plate 315 may be in the range of 1.5mm to 10mm to provide space to accommodate various robot arm sizes to lift or transport the wafer. In some embodiments, the distance between the wafer 320 and the conditioning plate 315 may be in the range of 3mm to 5mm to provide space to accommodate a certain type of robotic arm while providing more efficient heat transfer without special handling for robotic arm transport. In some embodiments, a special mechanism for lifting the wafer 320 may be used, making the distance narrower.

Further, even though two support structures 325 are shown in fig. 3A, it can be appreciated how the system 300a can include how many support structures 325. In some embodiments, the wafer 320 may be passively placed over the support structure 325 without any means for active coupling (e.g., electrostatic clamping). In other embodiments, the wafer 320 may be held to the support structure 325 using an active holding device, such as electrostatic clamping.

The load lock system 300a may include a load lock chamber 310, such as the load lock chamber 20 of fig. 1A. In some embodiments, the load lock chamber 310 may be configured to change the internal pressure between atmospheric pressure and vacuum. A pump, such as a turbo pump (not shown), may be connected to the load lock chamber 310 to maintain the vacuum level at an appropriate level for regulating the temperature of the wafer 320. It is understood that the pump may be a type of pump other than a turbo pump, so long as the pump is adapted to establish a vacuum in the load lock chamber 310.

In some embodiments, the conditioning plate 315 may include a heat transfer element 340, the heat transfer element 340 configured to change the temperature of the conditioning plate 315, which in turn affects the temperature of the wafer 320. The heat transfer element 340 may be coupled to a heater/cooler 360. In some embodiments, the heater/cooler 360 may be placed outside the load lock chamber 310. In other embodiments, the heater/cooler 360 may be placed inside the load lock chamber 310.

The load lock system 300a may also include a controller 350, the controller 350 configured to adjust the heater/cooler 360 or the heat transfer element 340 to change the temperature of the conditioning plate 315, which in turn affects the temperature of the wafer 320. In some embodiments, the controller 350 may receive stage temperature data regarding the temperature of the wafer stage 395 in the main chamber 390. For example, in some embodiments, the controller 350 may receive electrical signals conveying stage temperature data from a temperature sensor 396 configured to measure the temperature of the wafer stage 395. In such embodiments, the controller 350 may control the heater/cooler 360 to adjust the temperature of the conditioning plate 315 based on stage temperature data regarding the temperature of the wafer stage 395.

In some embodiments, the controller 350 may receive heater temperature data regarding the temperature of the output of the heater/cooler 360. In such embodiments, controller 350 may control heater/cooler 360 to adjust the temperature of regulation plate 315 based on heater temperature data. For example, in some embodiments, heater/cooler 360 may be a water heater or a water cooler. In such embodiments, the heated or cooled water flows through the heat transfer element 340 in the conditioning plate 315, and the controller 350 may receive heater temperature data regarding the temperature of the water at the output of the heater/cooler 360. The controller 350 may adjust the heater/cooler 360 based on the temperature of the water. In some embodiments, the controller 350 may receive electrical signals conveying heater temperature data from a temperature sensor 365 configured to measure the temperature of the water. In some embodiments, controller 350 may use both the table temperature data and the heater temperature data to adjust the temperature of conditioning plate 315. In such an embodiment, for example, the controller 350 may adjust the heater/cooler 360 to match the heater temperature (e.g., the temperature of the water at the output of the heater/cooler 360) to the temperature of the wafer stage 395.

In some embodiments, additional temperature sensors may be used to further optimize the controller 350. For example, in some embodiments, the system may include one or more additional sensors configured to measure the temperature of wafer 320 and conditioning plate 315.

In some embodiments, the load lock system 300a may include one or more exhaust ports (e.g., exhaust ports 330 or 335) to feed gas 338 from a gas supply into the load lock chamber 310. In such embodiments, gas 338 may increase thermal conduction between wafer 320 and conditioning plate 315, resulting in a decrease in the time for wafer 320 to reach a stable temperature. For example, heat transfer between wafer 320 and conditioning plate 315 may be generated by radiation and gas 338. The gas 338 may be nitrogen, helium, hydrogen, argon, CO2, or compressed dry air. It should be understood that gas 338 may be any other gas suitable for heat transfer. Valves 370 and 375 are provided between the gas supply and the load lock chamber 310. Exhaust holes 330 and 335 may be connected to a gas supply by gas lines extending from the gas supply to exhaust holes 330 and 335, which may lead to load lock chamber 310 to provide gas between wafer 320 and conditioning plate 315. In some embodiments, the vent holes 330 and 335 may be opened after the load lock chamber is evacuated to a vacuum level. In some embodiments, a load lock vacuum pump (e.g., a turbo pump) may be enabled to continuously remove some molecules of gas 338 and maintain a vacuum level during wafer conditioning when gas 338 is supplied into the load lock chamber 310.

As shown in fig. 3F, the heat transfer efficiency increases as the air pressure increases. However, when the gas pressure approaches a certain level, for example, 100Pa or more in fig. 3F, the efficiency may not be further improved. Thus, in some embodiments, the gas pressure in the space between wafer 320 and conditioning plate 315 may be in the range of 50Pa to 5,000Pa during conditioning of wafer 320 to provide efficient heat transfer while keeping the gas pressure level sufficiently low. In some embodiments, the gas pressure may be in the range of 100Pa to 1,000Pa during conditioning of the wafer 320 to provide a balance between heat transfer efficiencies while keeping the gas pressure close to vacuum.

In some embodiments, gas 338 may be temperature regulated so that the gas molecules themselves may provide heat transfer to wafer 320. For example, the gas supply, gas valves 370 and 375, or any other portion of load lock system 300a may include a heater to pre-condition the temperature of gas 338 prior to providing gas 338 into chamber 310.

In some embodiments, as shown in fig. 3A, one or more vent holes 330 and 335 may be included in the load lock chamber 310. In other embodiments, such as the load lock system 300B shown in fig. 3B, at least one vent hole (e.g., vent hole 330 in fig. 3B) may be included in the conditioning plate 315 and provide gas 338 directly into the space between the wafer 320 and the conditioning plate 315. For example, in such embodiments, vent 330 may be included in conditioning plate 315 and located at or near the center of wafer 320. It is understood that the vent holes may be located in any other location as long as the vent holes are suitable for providing gas 338 into the space between the wafer 320 and the adjustment plate 315 in the load lock chamber 310. It is also understood that the load lock systems 300a and 300b may include any number of vent holes. In some embodiments, the controller 350 may be configured to adjust the vent holes 330 or 335 to vary the gas flow rate into the load lock chamber 310.

Fig. 3C illustrates an exemplary graph showing wafer temperature as a function of time during wafer temperature conditioning in a load lock system. Temperature of the wafer (T) as heat is transferred to the wafer_wafer) Gradually approaches the temperature (T) of the wafer stage_{wafer stage}). When the wafer temperature reaches a stable temperature (T)_stable) The adjustment process may be completed. In some embodiments, T_stableMay be the same as the temperature of the wafer stage. In other embodiments, T_stableMay be set to be lower than the wafer stage temperature by about 100mKValue of (T)_{wafer stage}100mK) to provide effective yield enhancement. In some embodiments, T_stableMay be a set value of about 22 deg.c. In other examples, T_stableMay be set in the range of 20-28 c.

In some embodiments, as shown in FIG. 6C, when T is_waferApproach to T_stableIn time, a controller (such as controller 350 in fig. 3A) may adjust a heater (such as heater/cooler 360 in fig. 3A) such that the conditioning plate temperature may be gradually lowered to prevent overshoot of the wafer temperature.

T has been reached after wafer 320_stableThereafter, the conditioning step ends, after which the flow of gas through the exhaust holes (such as exhaust holes 330 and 335 in FIG. 3A) may be stopped. In some embodiments, after stopping the gas flow, the loadlock vacuum pump may continue to operate until the pressure in the loadlock chamber (such as loadlock chamber 310 in fig. 3A) becomes equal to or close to the pressure in the main chamber (such as main chamber 390 in fig. 3A). Since the pressure inside the loadlock chamber may have been maintained near vacuum (e.g., 10-10,000Pa), the pressure differential between the loadlock chamber and the main chamber may be relatively small. In some embodiments, a heater (such as heater/cooler 360 in fig. 3A) may maintain the temperature of the conditioning plate so that residual radiation from the conditioning plate may help maintain the temperature of the wafer during evacuation.

In some embodiments, when the gas pressure in the load lock chamber reaches or approaches the pressure in the main chamber, the wafer may be transported to a wafer station (such as wafer station 395 in fig. 3A) for inspection. Because the temperature of the wafer may be equal to or close to the temperature of the wafer stage, the inspection may begin with minimal latency. In other embodiments, the wafer may be transported to a docking station (such as docking station 70 of FIG. 1B) and temporarily stored until the ongoing inspection of the previous wafer is complete.

Referring now to fig. 3D, fig. 3D illustrates another example load lock system 300D, according to an embodiment of the present disclosure. In some embodiments, load lock system 300d may include a plurality of support structures 325 and conditioning plates 315 configured to transfer heat to wafer 320. In some embodiments, the conditioning plate 315 may include a heat transfer element 340.

In some embodiments, as shown in fig. 3D, conditioning plate 315 may be positioned over wafer 320. In such embodiments, the wafer 320 is supported by a support structure 325 coupled to the support plate 319. However, it is understood that more efficient heat transfer may be achieved as the wafer 320 is positioned closer to the conditioning plate 315, and in some embodiments it may be desirable to have sufficient distance between the wafer 320 and the conditioning plate 315 to provide space for a robotic arm to lift or transport the wafer 320. However, in FIG. 3D, since the adjustment plate 315 is located above the wafer 320, the adjustment plate 315 can be placed closer to the wafer 320. In some embodiments, the distance between wafer 320 and adjustment plate 315 may be reduced to about 1 mm.

In some embodiments, load lock system 300d may include vent holes 330 and 335 to provide gas 338 to the space between wafer 320 and conditioning plate 315. In some embodiments, at least one vent may be included in the modulation plate 315 to provide gas 338 to the space. It should be understood that the exhaust holes 330 or 335 may be located at other locations of the load lock system 300d, so long as the locations are suitable for providing the gas 338 into the space between the wafer 320 and the conditioning plate 315 in the load lock chamber 310. It should be appreciated that the load lock system 300d may include any number of vent holes.

Referring now to fig. 3E, fig. 3E illustrates another example load lock system 300E, according to an embodiment of the present disclosure. The load lock system 300e may include a plurality of conditioning plates configured to transfer heat to the wafer 320 from multiple directions. For example, load lock system 300e may include an upper adjustment plate 317 configured to transfer heat in a downward direction and a lower adjustment plate 318 configured to transfer heat in an upward direction. In some embodiments, the upper conditioning plate 317 may include a heat transfer element 340. In some embodiments, the lower adjustment plate may include a heat transfer element 340. Lower adjustment plate 318 may be coupled to a support structure 325 configured to support wafer 320. Load lock system 300e may include vent holes 330 and 335 to provide gas 338 to the space between wafer 320 and conditioning plates 317 and 318. In some embodiments, upper adjustment plate 317 may include at least one vent hole therein. Lower adjustment plate 318 may include at least one vent hole therein.

Referring now to fig. 4, fig. 4 is a schematic diagram of a prealigner in an equipment front end module EFEF of an embodiment of the present disclosure. In some embodiments, the prealigner may include one or more support structures 425 configured to support the wafer 420 and a conditioning plate 415 configured to transfer heat from the one or more exhaust holes 440 via heated compressed air. In some embodiments, the conditioning plate 415 further includes one or more vacuum channels 450 configured to remove air. In such embodiments, heat transfer between wafer 420 and conditioning plate 415 may be primarily generated by convection via temperature conditioned compressed air provided via one or more exhaust vents 440. Since the wafer conditioning is performed by the forced convection of the temperature-conditioned compressed air, the heat transfer with the wafer 420 is effectively performed, and thus the wafer temperature can be rapidly stabilized to a stable temperature.

Referring now to fig. 5, fig. 5 shows a schematic diagram illustrating an exemplary configuration of a wafer conditioning system 500 according to an embodiment of the present disclosure. In some embodiments, wafer conditioning system 500 may include a plurality of support structures 525 and conditioning plates 515 configured to transfer heat to wafer 520. A support structure 525 coupled to the conditioning plate 515 may support the wafer 520 and conduct heat to the wafer 520. It should be appreciated that the support structure 525 may be any shape suitable for supporting and conducting heat. In some embodiments, conditioning plate 515 may include a heat transfer element 540, the heat transfer element 540 configured to change the temperature of conditioning plate 515, which in turn affects the temperature of wafer 520. The heat transfer element 540 may be coupled to a heater 560. In some embodiments, the heater 560 may be placed outside the vacuum chamber 510. In other embodiments, the heater 560 may be placed inside the vacuum chamber 510.

In some embodiments, the conditioning plate 515 may also include an electrostatic clamp 570. The electrostatic clamp 570 can hold the wafer 520 to the conditioning plate 515 via an electrical charge. A power supply (not shown) provides an electrical charge that connects the wafer 520 to the electrostatic chuck 570. For example, the electrostatic clamp 570 may be part of the tuning plate 515 or included in the tuning plate 515. In other examples, the electrostatic clamp 570 may be separate from the adjustment plate 515. In some embodiments, the conditioning plate 515 may include a lifting structure 526 configured to lift the wafer 520 to accommodate a robotic arm (not shown) for transporting the wafer 520.

In some embodiments, the vacuum chamber 510 can include a heat transfer element 545 configured to change the temperature of the vacuum chamber 510. In such embodiments, heat may be transferred from the inner surfaces of the vacuum chamber 510 to the wafer 520 via radiation (as shown in FIG. 5). The vacuum chamber 510 may be the load lock chamber 20 of FIG. 1B, a portion of the docking station 70 of FIG. 1B, or the main chamber 10 of FIG. 1B.

Referring now to fig. 6A, fig. 6A shows a schematic diagram illustrating another exemplary configuration of a wafer conditioning system 600 according to an embodiment of the present disclosure. The system 600 may include a vacuum chamber 610 and one or more support structures 625 configured to support a wafer 620. In some embodiments, wafer conditioning system 600 may include one or more heating devices configured to transfer heat to wafer 620 via radiation from multiple directions. For example, as shown in fig. 6A, system 600 may include an upper heating device 617 and a lower heating device 618.

In some embodiments, heating devices 617 or 618 may be a regulating plate, one or more tubes, or one or more coils configured to radiate heat to wafer 620. In some embodiments, system 600 may include a single heating device, which may be positioned above or below wafer 620. In some embodiments, system 600 may include an upper heating device 617 and a lower heating device 618 positioned relative to wafer 620. In some embodiments, system 600 may include three or more heating devices. In some embodiments, the system 600 may include a heater 660 configured to provide heat to the heating device 617 or 618. In some embodiments, heater 660 may be a water heater or any other type of heater that may provide heat to heating devices 617 or 618.

In some embodiments, the support structure 625 may include a temperature sensor 627 configured to measure a temperature of the wafer 620. Temperature sensor 627 may include a Thermocouple (TC), an NTC thermistor, a PTC thermistor, a resistance thermometer, an infrared thermometer, or any other device suitable for measuring the temperature of wafer 620. For example, as shown in fig. 6B, the support structure 625 may include a thermocouple configured to measure the temperature of the wafer 620. To enable measurement of the temperature of the wafer, the support structure 625 may include a spring-like structure to push the thermocouple into contact with the wafer 620. In some embodiments, the thermocouple and spring-like structure may be surrounded by a support structure 625.

Since the system 600 operates in the vacuum chamber 610, heat transfer from the wafer to the thermocouple for measuring the temperature of the wafer can occur via conduction and radiation. For some embodiments, it may be desirable to minimize thermal radiation to the thermocouple in order to more accurately measure the temperature of wafer 620. Thus, in addition to the surface in contact with wafer 620, the surface of the thermocouple may be covered by one or more structures made of a material that does not transfer heat, such that the thermocouple may receive heat via conduction from wafer 620. In some embodiments, the support structure 625 may be made of a material that prevents heat transfer. In some embodiments, system 600 may include a plurality of thermocouples to collect temperature information from multiple portions of wafer 620. In such an embodiment, a controller (such as controller 650 shown in fig. 6E) may determine the temperature profile of wafer 620.

Referring now to fig. 6C, fig. 6C is an exemplary graph illustrating temperature changes during an adjustment process. The wafer conditioning system may include a control mechanism to instantaneously change the temperature of the heating device while the wafer conditioning is being performed. Further, in some embodiments, the wafer conditioning system may include one or more temperature sensors configured to measure the temperature of various portions of the system. In some embodiments, the wafer conditioning system may include one or more temperature sensors configured to measure the temperature of the wafer itself. Fig. 6C shows the temperature over time in an example of such an embodiment. In such an embodiment, the temperature of the heating device may be high (even at high temperatures)Above the desired stabilization temperature T_stable) Starting the regulation process and then following T_waferApproach to T_stableWhile gradually lowering the temperature to the desired stable temperature. In some embodiments, the process may be further optimized by temperature information from the sensors. Controlling the temperature in this manner can significantly reduce conditioning time, as shown in fig. 6C.

Referring now to fig. 6D, fig. 6D is a schematic diagram of an exemplary control circuit of a wafer conditioning system, according to an embodiment of the present disclosure. In some embodiments, a wafer conditioning system, such as system 600 in fig. 6A, may include a controller and one or more temperature sensors configured to measure various portions of the system. In some embodiments, the wafer conditioning system may include one or more temperature sensors configured to measure the temperature of the wafer. For example, the controller 650 may receive temperature data regarding the temperature of an incoming wafer from a temperature sensor 696 in an equipment front end module (such as the EFEM30 of FIG. 1A). The controller 650 may receive wafer temperature data regarding the temperature of the wafer from the temperature sensor 627. Controller 650 may receive heater temperature data from temperature sensor 665 regarding the temperature of the output of heater 660 (e.g., water at the output of the water heater). In some embodiments, controller 650 may control heater 660 based on at least one temperature data from sensors 696, 627, and 665. For example, the heater 660 may comprise an electric water heater configured to transfer heat to water. Using temperature feedback, the controller 650 can adjust the current provided to the heater 660, thereby causing the temperature of the heat transfer element (e.g., heating device 617 or 618 in fig. 6A) to change. In some embodiments, the controller 650 may be calibrated based on the type or condition of the wafer.

Even though the control mechanism is described in the context of the system 600 of fig. 6A, it should be understood that the same control mechanism may be applied to any embodiment of the wafer conditioning system shown in the present disclosure.

Referring now to fig. 7, fig. 7 is a flow chart illustrating an exemplary method for regulating wafer temperature in accordance with an embodiment of the present disclosure. The method may be performed by a load lock system (e.g., load lock systems 300a, 300b, 300D, and 300e of fig. 3A-3D) of an electron beam system (e.g., charged particle beam inspection system 100 of fig. 1A).

In step 710, a wafer is loaded into the load lock chamber relative to the conditioning plate by the robotic arm. In some embodiments, a wafer may be placed over the conditioning plate. In other embodiments, the wafer may be placed under the conditioning plate. In some embodiments, the wafer may be placed between two conditioning plates.

In step 720, after loading the wafer into the load lock chamber (e.g., load lock chamber 20 in fig. 1A), the controller (e.g., controller 50 of fig. 1A) enables the vacuum pump to remove air from the load lock chamber.

In step 730, the temperature of a wafer stage (e.g., wafer stage 395 of fig. 3A) is determined and provided to a controller.

In step 740, a gas supply (e.g., the gas supply in fig. 3A) provides gas to the load lock chamber for heat transfer between the conditioning plate and the wafer. The gas may be temperature regulated to match the measured temperature of the wafer stage to provide more efficient heat transfer.

In step 750, the controller receives the wafer stage temperature data and adjusts the heating temperature based on the determined temperature of the wafer stage.

In step 760, after wafer conditioning is complete, the wafer conditioning system transports the conditioned wafer from the load lock chamber to a main chamber (e.g., main chamber 390 in fig. 3A) or a docking station (e.g., docking station 70 in fig. 3B). In some embodiments, if there is a temperature sensor for measuring the temperature of the wafer, the controller may monitor the wafer temperature and determine whether the wafer conditioning is complete.

It should be understood that the controller of the wafer conditioning system may use software to control the above-described functions. For example, the controller may send instructions to the heater to change the temperature of the heat transfer element. The controller may also send instructions to adjust the input voltage or current to the heater. The software may be stored on a non-transitory computer readable medium. Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, a CD-ROM, any other optical data storage medium, any physical medium with patterns of holes, a RAM, a PROM, and EPROM, a cloud storage, a FLASH-EPROM, or any other FLASH memory, an NVRAM, a cache, registers, any other memory chip or cartridge, and network versions of the above.

Referring now to fig. 8A and 8B, fig. 8A and 8B show schematic diagrams illustrating an exemplary charged particle beam inspection system 800 having a vacuum pump system, according to an embodiment of the present disclosure. In some embodiments, charged particle beam inspection system 800 can include a main chamber 890 and a loadlock chamber 810. In some embodiments, the system 800 may include a gas supply 811, an exhaust valve 812, and an exhaust diffuser 813 coupled to the load lock chamber 810. The gas supply 811 may provide a gas (e.g., gas 338 of fig. 3A) into the load lock chamber 810 during wafer conditioning to increase thermal conductivity between a wafer (e.g., wafer 320 of fig. 3A) and a conditioning plate (e.g., conditioning plate 315 of fig. 3A). The gas may be nitrogen, helium, hydrogen, argon, CO2, or compressed dry air. It should be understood that the gas may be any other gas suitable for heat transfer.

In some embodiments, the vacuuming of the load lock chamber 810 may be performed in two stages via two separate paths. This first path is referred to as the rough path and may include a load lock rough line 816 and a load lock rough valve 853. At low vacuum levels, the load lock chamber 810 is evacuated from atmospheric conditions to a "rough" vacuum level (e.g., 5 × 10)^-1Torr). In the first stage, the load lock low vacuum valve 853 is opened to first evacuate the load lock chamber 810 via the load lock low vacuum line 816 while the other path is closed.

The second path is referred to as a turbo pumping path and may include a load lock turbo valve 814, a load lock turbo pump 815, a load lock turbo pump line 817, and a load lock turbo pump check (backing) valve 851. After the low vacuum of the load lock chamber 810 is completed, the load lock turbo pump 815 take over to pump down the load lock chamber 810 to a deeper vacuum level (e.g., below 1.5 x 10)^-6Torr). In this second stage, the load lock low vacuum valve 853 is first closed. Then, the load lock turbine valve 814 and the load lock turbine pump check valve 851 are opened so that the load lock turbine pump 815 evacuates the load lock chamber 810.

Main chamber 890 may be evacuated in a similar manner. First, the main chamber 890 is evacuated from atmospheric conditions to a "rough" vacuum level (e.g., 5 x 10) via a main chamber rough vacuum path (including a main chamber rough vacuum line 896 and a main chamber rough vacuum valve 854)^-1Torr). After the low vacuum stage is completed, the main chamber turbopump 895 takes over to further evacuate to a deeper vacuum level (e.g., below 1.5 x 10) via a main chamber turbopumping path (including a main chamber turbovalve 894, a main chamber turbopump 895, a main chamber turbopumping line 897, and a main chamber turbopump check (backing) valve 852)^-6Torr). In some embodiments, the main chamber turbo pump 895 may continue to run until the wafer inspection is complete.

Although fig. 8A shows the system 800 having one rough path and one turbine pumping path for the load lock chamber 810, it should be understood that the system may utilize any number of rough paths and turbine pumping paths to evacuate the load lock chamber 810. For example, the system 800 may have two or more low vacuum paths connected in parallel to the load lock chamber 810. Regardless of the number of low vacuum paths, the system 800 may have two or more turbo pumps connected in parallel to the load lock chamber 810. Similarly, it should be understood that the system may utilize any number of low vacuum paths and turbo pumping paths to evacuate main chamber 890.

In some embodiments, the system 800 may include a central manifold box 850, where all of the rough vacuum lines (e.g., the load-lock rough vacuum line 816 and the primary chamber rough vacuum line 896) and all of the pumping lines (e.g., the load-lock turbo pumping line 817 and the primary chamber turbo pumping line 897) are merged in the central manifold box 850. Central manifold box 850 may house a plurality of valves to control the vacuuming process. For example, central manifold box 850 may include a load lock rough valve 853, a main chamber rough valve 854, a load lock turbo pump check valve 851, and a main chamber turbo pump check valve 852. After these individual valves, all lines are combined into a preceding line 858. The final exhaust by the dry vacuum pump 860 is controlled by a pre-line valve 859, which pre-line valve 859 may be located before the dry vacuum pump 860.

As described in the previous section with respect to fig. 3A, in some embodiments, during wafer temperature conditioning, the load lock chamber 810 may be continuously evacuated via the rough vacuum line 816 or turbo pump 815 to continuously remove some gas molecules (e.g., gas 338 of fig. 3A) and maintain the vacuum level of the load lock chamber 810 until wafer conditioning is complete.

As shown in fig. 8B, in some embodiments, such continuous evacuation of the load lock chamber 810 may introduce a temporary pressure jump in the shared preceding line (e.g., preceding line 858), causing the inspection process in the main chamber 890 to be interrupted. For example, as described in the previous section, a wafer temperature conditioning process may be performed in the load lock chamber 810 while a previous wafer is being examined in the main chamber 890. However, when the load lock rough valve 853 is opened to begin the continuous evacuation process, the pressure in the pre-line 858 may increase because the high pressure conditions in the load lock chamber 810 are exposed to the pre-line 858 due to the open connection established through the load lock rough line 816. The elevated pressure in the foreline 858 may create a higher back pressure to the primary chamber turbopump 895. Because in some embodiments, the main chamber turbo pump 895 may be running simultaneously to maintain a low pressure level in the main chamber during inspection of a preceding wafer when wafer temperature adjustment is performed in the load lock chamber 810, a sudden increase in backpressure may affect the dynamic behavior of the turbo pump 895. As a result, sudden vibrations may occur to the system 800. Such sudden vibrations may cause inspection errors. Thus, if the vibration level is higher than the margin of inspection error, the inspection process may need to be suspended until the back pressure disappears and the vibration is attenuated. Interruptions in the inspection process may compromise system throughput. The increased back pressure may also cause the effective pumping speed of turbopump 895 to decrease, temporarily increasing the pressure in main chamber 890. This temporary increase in main chamber pressure may also affect system throughput and overall system performance. This effect is explained in more detail in the next section with respect to fig. 9.

Referring now to fig. 9, fig. 9 is an exemplary graph illustrating pressure variations in a main chamber (e.g., main chamber 890 of fig. 8A and 8B) of a charged particle beam inspection system (e.g., charged particle beam inspection system 800 of fig. 8A and 8B). As explained above with respect to fig. 8A, the main chamber is evacuated in two stages (low vacuum stage 911 and turbo-evacuation stage 912). During the rough stage 911, the main chamber is evacuated from atmospheric conditions to a "rough" vacuum level 910 (e.g., 5 x 10) via a rough vacuum path^-1Torr). After the main chamber pressure reaches the "rough" vacuum level 910, the roughing valve (e.g., the main chamber roughing valve 854 of fig. 8A) is closed and the main chamber turbo pump (e.g., the main chamber turbo pump 895) takes over to further reduce the main chamber pressure to a deeper vacuum level. When the main chamber pressure becomes lower than the "check ready" vacuum level 920 (e.g., 1.5 x 10)^-6Torr), the wafer inspection process may begin. In some embodiments, the primary chamber turbo pump 895 may continue to operate to maintain the primary chamber pressure level near the "check ready" level 920.

When the inspection of the first wafer is complete, in some embodiments, a wafer swap may occur at time period 923. During wafer exchange, the main chamber pressure may temporarily increase due to the opening of a gate valve (e.g., gate valve 26 of fig. 1) between the load lock chamber (e.g., load lock chamber 810 of fig. 8A) and the main chamber (e.g., main chamber 890 of fig. 8A). After the wafer exchange, once the main chamber turbo pump reduces the main chamber pressure to the "check ready" vacuum level 920, the inspection process can begin again.

Before the wafer swap, while the first wafer is being inspected in the main chamber, the second wafer may undergo a wafer temperature conditioning process, and as described above, the main chamber pressure may temporarily increase due to the back pressure applied to the main chamber turbo pump. An example of a temporary pressure jump 950 is shown in the graph.

If the temporary pressure jump 950 remains below the "check ready" vacuum level 920, the first wafer may continue to be checked without interruption as long as the vibration level remains within the error range. However, if the main chamber pressure increases above the "check ready" vacuum level 920 during the temporary transition 950, then the inspection of the first wafer may need to be paused until the main chamber pressure returns to the "check ready" level. As a result, system throughput may be affected by the interruption.

Referring now to fig. 10, fig. 10 shows a schematic diagram illustrating an exemplary charged particle beam inspection system 1000 with an improved vacuum pump system, in accordance with an embodiment of the present disclosure. In some embodiments, a separate pumping path may be added to loadlock chamber 810 to prevent vibration and pressure jumps in main chamber 890. For example, in some embodiments, charged particle beam inspection system 1000 may include a loadlock booster roughing valve 1010, a loadlock booster roughing pump 1011, and an auxiliary exhaust system 1012. All other parts of the system 1000 are the same as the system 800 of fig. 8A.

In such an embodiment, the load-lock boost roughing pump 1011 may be continuously operated to remove gas molecules (e.g., gas 338 of fig. 3A) during wafer temperature conditioning. However, since the load lock low vacuum valve 853 and the load lock turbo pump check valve 851 remain closed during this time, there is no increase in pressure in the front line 858 and therefore no back pressure is created on the main chamber turbo pump 895.

Thus, in some embodiments, the evacuation process for the load lock chamber 810 may be divided into three stages. First, the load-lock boost roughing pump 1011 may operate from atmospheric conditions (after receiving a new set of wafers from an EFEM (e.g., the EFEM30 of fig. 1A)) to a vacuum level for wafer temperature conditioning. Second, the normal load lock rough path (via load lock rough line 816) may regulate the vacuum level from the wafer temperature to a "rough or low" vacuum level operation. Finally, the load lock turbo pump 815 may operate from a "rough" vacuum level to a deeper vacuum level. The backpressure problem is greatest at the beginning of near atmospheric pumping when the foreline 858 is in the viscous regime. Thus, after lowering the pressure level of the loadlock chamber to the wafer temperature regulated vacuum level by a separate booster pump (e.g., loadlock booster roughing pump 1011), for example, a conventional pumping mechanism (e.g., loadlock roughing line 816 or loadlock turbo pump 815) may be used without generating excessive back pressure.

Referring now to fig. 11, fig. 11 is a flow chart illustrating an exemplary method for controlling the vacuum level of a load lock chamber of the charged particle beam inspection system of fig. 10, according to an embodiment of the present disclosure. The method may be performed by the charged particle beam inspection system of fig. 10.

In step 1110, a wafer (or wafers) is loaded into a load lock chamber (e.g., load lock chamber 810 of FIG. 10) by a robotic arm (e.g., robotic arm 11 of FIG. 1B).

In step 1111, a gas supply (e.g., gas supply 811 of FIG. 10) begins to provide gas (e.g., gas 338 of FIG. 3A) to the load lock chamber for wafer temperature regulation.

In step 1112, all gates (e.g., gate valves 25 and 26 of fig. 1B) are closed in preparation for the vacuumization process. In some embodiments, step 1111 may occur after all gates are closed in step 1112.

In step 1113, the booster pump valve (e.g., load lock booster roughing valve 1010) is opened and the booster pump (e.g., load lock booster roughing pump 1011) begins to evacuate the load lock chamber. As explained above with respect to fig. 10, at this first stage, the load lock chamber is evacuated from atmospheric conditions to a vacuum level suitable for wafer temperature regulation. Because the booster pump line is connected to a separate exhaust system (e.g., the auxiliary exhaust system 1012 of fig. 10) and is not merged with the normal low vacuum path to form a shared preceding line (e.g., the preceding line 858 of fig. 10) in a manifold (e.g., the central manifold 850 of fig. 10), the booster pump does not cause back pressure in the preceding line. Therefore, system throughput is not affected.

In step 1114, the wafer conditioning process begins. This step may include basing the process on that in a main chamber (e.g., main chamber 890 of FIG. 10)The determined temperature of the wafer stage (e.g., wafer stage 395 of fig. 3A) adjusts a heating temperature of the conditioning plate (e.g., conditioning plate 315 of fig. 3A). While the wafer temperature adjustment is performed, the booster pump continues to operate to maintain a vacuum level suitable for the wafer temperature adjustment. In step 1115, when the wafer temperature reaches a stable temperature (e.g., T in FIG. 3C)_stable) The adjustment process is complete.

In step 1116, after the wafer temperature adjustment is complete, the exhaust valve (e.g., exhaust valve 812 of fig. 10) is closed and the gas supply is stopped. In step 1117, the first stage of the evacuation process is complete and the pressurization valve (e.g., load-lock pressurization low vacuum valve 1010) is closed.

In step 1118, the second stage of the evacuation process begins by opening a load lock rough valve (e.g., load lock rough valve 853 of fig. 10). At this second stage, in some embodiments, the load lock chamber may be evacuated from the wafer conditioning vacuum level to a "rough" vacuum level (e.g., 5 x 10)^-1Torr). After the "rough" vacuum level is reached, the load lock rough vacuum valve is closed in step 1119.

In step 1120, the third stage of the evacuation process begins and a turbo pump (e.g., load lock turbo pump 815) takes over to evacuate the load lock chamber 810 to a deeper vacuum level near the main chamber pressure.

In step 1121, after the wafer inspection of the preceding wafer is completed, the preceding wafer is taken out from the main chamber and the temperature-adjusted wafer is transferred from the load lock chamber to the main chamber. In step 1122, when the wafer exchange is complete, the load lock turbo pump valve is closed.

After step 1122, step 1110 may be performed to load a new set of wafers into the load lock chamber. If an unconditioned and unchecked wafer is still present in the load lock chamber, the system can proceed to step 1111 to condition another wafer in preparation for the inspection process.

It should be understood that the controller of the wafer conditioning system may use software to control the above-described functions. For example, the controller may send commands to the aforementioned valves and pumps to control the evacuation path. The software may be stored on a non-transitory computer readable medium. Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, a CD-ROM, any other optical data storage medium, any physical medium with patterns of holes, a RAM, a PROM, and EPROM, a cloud storage, a FLASH-EPROM, or any other FLASH memory, an NVRAM, a cache, registers, any other memory chip or cartridge, and network versions of the above.

Embodiments may be further described using the following clauses:

1. a load lock system, comprising:

a plurality of support structures configured to support a wafer;

a first regulating plate including a first heat transfer element configured to regulate a temperature of the wafer;

a first exhaust hole configured to provide a gas between the first conditioning plate and the wafer; and

a controller comprising a processor and a memory, the controller configured to facilitate control of the first heat transfer element.

2. The load lock system of clause 1, wherein the first conditioning plate is positioned above the wafer.

3. The load lock system of clause 1, wherein the first conditioning plate is located below the wafer.

4. The load lock system of clause 3, wherein the plurality of support structures are coupled to the first modulation plate.

5. The load lock system according to any one of clauses 1 to 4, wherein the first venting aperture is attached to the first regulating plate.

6. The load lock system of any of clauses 1 to 5, wherein the controller is further configured to assist control of the first heat transfer element based on a temperature of a wafer table.

7. The load lock system according to any of clauses 1 to 6, wherein the controller is further configured to control the flow of gas through the first venting orifice.

8. The load lock system of any of clauses 1 to 7, further comprising a second conditioning plate comprising a second heat transfer element configured to condition a temperature of the wafer.

9. The load lock system of clause 8, wherein the plurality of support structures configured to support a wafer are positioned between the first conditioning plate and the second conditioning plate.

10. The load lock system of clause 9, further comprising a second vent configured to provide a portion of the gas between the second conditioning plate and the wafer.

11. The load lock system of clause 10, wherein the second vent aperture is coupled to the second modulation plate.

12. The load lock system of any of clauses 8 to 11, wherein the controller is further configured to assist in controlling the second heat transfer element based on a temperature of the wafer stage.

13. The load lock system of any of clauses 10-12, wherein the controller is further configured to control a flow of gas through the second vent.

14. The load lock system according to any of clauses 1 to 13, wherein the gas comprises: nitrogen, helium, hydrogen, argon, CO2, or compressed air.

15. The load lock system according to any of clauses 1 to 14, further comprising a load lock chamber configured to enclose the first conditioning plate, the plurality of support structures, and the wafer.

16. The load lock system of clause 15, further comprising a first vacuum pump connected to the load lock chamber.

17. The load lock system of clause 16, wherein the controller is further configured to control the first vacuum pump to pump out the gas during wafer conditioning.

18. The load lock system of clause 17, wherein the controller is further configured to maintain a pressure inside the load lock chamber within a range of 50Pa to 5,000Pa during the wafer conditioning.

19. The load lock system according to any of clauses 16 to 18, further comprising a second vacuum pump connected to the load lock chamber.

20. The load lock system of clause 19, wherein the controller is further configured to:

enabling the first vacuum pump to reduce the pressure inside the load lock chamber to a first pressure level, an

Enabling the second vacuum pump to reduce a pressure inside the load lock chamber to a second pressure level, wherein the second pressure level is lower than the first pressure level.

21. The loadlock system of clause 20, wherein the second vacuum pump shares an exhaust path with a third vacuum pump connected to a main chamber.

22. The load lock system of any of clauses 20 and 21, wherein the second vacuum pump is disabled while the first vacuum pump is enabled.

23. The load lock system according to any one of clauses 20 to 22, wherein the first vacuum pump and the third vacuum pump are activated simultaneously.

24. A method of thermal conditioning of a wafer in a load lock system, the method comprising:

loading a wafer into a load lock chamber of a load lock system;

evacuating the load lock chamber;

providing a gas to the load lock chamber; and

such that a first heat transfer element in a first conditioning plate can adjust the temperature of the first conditioning plate to transfer heat to the wafer through the gas.

25. The method of clause 24, wherein providing gas to the load lock chamber further comprises: adjusting a temperature of the gas prior to providing the gas to the load lock chamber.

26. The method of any of clauses 24 and 25, wherein providing gas to the load lock chamber further comprises: supplying the gas to a space between the first regulating plate and the wafer.

27. The method of any of clauses 24 to 26, further comprising: the temperature of the wafer stage in the main chamber is determined.

28. The method of any of clauses 24 to 27, wherein enabling the first heat transfer element to adjust the temperature of the first adjustment plate further comprises: adjusting the first heat transfer element based on the determined temperature of the wafer stage.

29. The method of any of clauses 24 to 28, further comprising: such that a second heat transfer element in a second conditioning plate can adjust the temperature of the second conditioning plate to transfer heat through the gas to the wafer.

30. The method of any of clauses 24 to 29, wherein the gas comprises: nitrogen, helium, hydrogen, argon, CO2, or compressed air.

31. The method of any of clauses 24 to 30, wherein evacuating the load lock chamber comprises: pumping the gas out of the load lock chamber using a first vacuum pump connected to the load lock chamber.

32. The method of clause 31, wherein evacuating the load lock chamber further comprises:

enabling the first vacuum pump to reduce a pressure inside the load lock chamber to a first pressure level; and

enabling a second vacuum pump coupled to the load lock chamber to reduce a pressure inside the load lock chamber to a second pressure level, wherein the second pressure level is lower than the first pressure level.

33. The method of clause 32, wherein the second vacuum pump shares an exhaust path with a third vacuum pump connected to the main chamber.

34. The method of any of clauses 32 and 33, wherein the second vacuum pump is disabled while the first vacuum pump is enabled.

35. The method of any of clauses 32 to 34, wherein the first vacuum pump and the third vacuum pump are activated simultaneously.

36. A non-transitory computer-readable medium comprising a set of instructions executable by one or more processors of a controller to cause the controller to perform a method of performing thermal conditioning of a wafer, the method comprising:

instructing a first vacuum pump to evacuate a load lock chamber of a load lock system after a wafer is loaded into the load lock chamber;

instructing a gas supply to provide gas to the load lock chamber; and

instructing a first heat transfer element in a first conditioning plate to adjust a temperature of the first conditioning plate to transfer heat to the wafer through the gas.

37. The computer-readable medium of clause 36, wherein the set of instructions is executable by the one or more processors of the controller to cause the controller to further perform:

the temperature sensor is instructed to determine a temperature of the wafer stage in the main chamber.

38. The computer readable medium of clause 37, wherein instructing the first heat transfer element in the first regulating plate further comprises: adjusting the first heat transfer element based on the determined temperature of the wafer stage.

39. The computer-readable medium of any of clauses 36-38, wherein the set of instructions is executable by the one or more processors of the controller to cause the controller to further perform:

instructing a second heat transfer element in a second conditioning plate to adjust a temperature of the second conditioning plate to transfer heat to the wafer through the gas.

40. The computer readable medium of clause 39, wherein instructing the second heat transfer element in the second conditioning plate further comprises: adjusting the second heat transfer element based on the determined temperature of the wafer stage.

41. The computer-readable medium of any of clauses 36-40, wherein the set of instructions is executable by the one or more processors of the controller to cause the controller to further perform:

instructing the first vacuum pump to evacuate the load lock chamber to a first pressure level; and

instructing the second vacuum pump to evacuate the load lock chamber to a second pressure level, wherein the second pressure level is lower than the first pressure level.

42. A method of evacuating a load lock chamber, the method comprising:

pumping gas out of the load lock chamber with a first vacuum pump configured to discharge the gas to a first exhaust system; and

pumping the gas out of the load lock chamber with a second vacuum pump configured to discharge the gas to a second exhaust system.

43. The method of clause 42, further comprising:

enabling the first vacuum pump to reduce a pressure inside the load lock chamber to a first pressure level; and

enabling the second vacuum pump to reduce a pressure inside the load lock chamber to a second pressure level, wherein the second pressure level is lower than the first pressure level.

44. The method of clause 43, wherein the second vacuum pump shares the second exhaust system with a third vacuum pump configured to evacuate a main chamber.

45. The method of any of clauses 42 to 44, wherein the second vacuum pump is disabled while the first vacuum pump is enabled.

46. The method of any of clauses 44-45, wherein the first vacuum pump and the third vacuum pump are activated simultaneously.

Although the disclosed embodiments have been described with respect to preferred embodiments thereof, it should be understood that other modifications and variations may be made without departing from the spirit or scope of the subject matter as hereinafter claimed.