阅读说明：本技术 用于针对移动的工艺套件测量侵蚀并校准位置的方法和装置 (Method and apparatus for measuring erosion and calibrating position for a moving process kit ) 是由 C·G·波特 E·莫 S·洛佩兹卡巴加尔 于 2019-08-23 设计创作，主要内容包括：本文中所公开的实施例包括一种校准处理腔室的方法。在实施例中,该方法包括以下步骤：将传感器晶片放置到处理腔室中的支撑表面上,其中在Z方向上能移位的工艺套件定位在支撑表面周围。在实施例中,该方法进一步包括以下步骤：用该传感器晶片的边缘表面上的传感器测量传感器晶片与工艺套件之间的第一间隙距离。在实施例中,该方法进一步包括以下步骤：使工艺套件在Z方向上移位。在实施例中,该方法进一步包括以下步骤：测量传感器晶片与工艺套件之间的额外间隙距离。(Embodiments disclosed herein include a method of calibrating a process chamber. In an embodiment, the method comprises the steps of: the sensor wafer is placed onto a support surface in a processing chamber, wherein a process kit displaceable in the Z-direction is positioned around the support surface. In an embodiment, the method further comprises the steps of: a first gap distance between the sensor wafer and the process kit is measured with a sensor on an edge surface of the sensor wafer. In an embodiment, the method further comprises the steps of: the process kit is displaced in the Z-direction. In an embodiment, the method further comprises the steps of: an additional gap distance between the sensor wafer and the process kit is measured.)

1. A method of calibrating a process chamber, the method comprising:

placing a sensor wafer onto a support surface in the process chamber, wherein a process kit displaceable in a Z-direction is positioned around the support surface;

measuring a first gap distance between the sensor wafer and the process kit with a sensor on an edge surface of the sensor wafer;

displacing the process kit in the Z-direction; and

an additional gap distance between the sensor wafer and the process kit is measured.

2. The method of claim 1, further comprising the steps of:

comparing the additional gap distance to the first gap distance.

3. The method of claim 2, further comprising the steps of:

removing the sensor wafer from the support surface when the first gap distance is equal to the additional gap distance.

4. The method of claim 2, further comprising the steps of:

the operations of displacing the process kit in the Z direction and measuring additional gap distances are repeated until successive measurements of the gap distances are equal to each other.

5. The method of claim 1, wherein the sensor is a capacitive sensor.

6. The method of claim 5, wherein the capacitive sensor is a self-referencing capacitive sensor.

7. The method of claim 6, wherein the capacitive sensor comprises a first pad and a second pad, and wherein the current supplied to the first pad has an output phase that is 180 degrees out of phase with the output phase of the current supplied to the second pad.

8. The method of claim 5, wherein the capacitive sensor extends above a top surface of the sensor wafer.

9. A method for measuring corrosion of a process kit, the method comprising the steps of:

placing a sensor wafer on a support surface in a processing tool;

aligning a top surface of a process kit surrounding the support surface with a top surface of a sensor wafer using a sensor on the sensor wafer;

removing the sensor wafer from the support surface;

processing one or more device substrates in the processing tool;

placing a sensor wafer on the support surface;

measuring a gap distance between the sensor wafer and the process kit with a sensor on an edge surface of the sensor wafer;

displacing the process kit in the Z-direction; and

measuring the gap distance between the sensor wafer and the process kit again; and

the operations of displacing the process kit and measuring the gap distance are repeated until successive gap distance measurements are equal to each other.

10. The method of claim 9, further comprising the steps of:

calculating a total displacement of the process kit in the Z-direction.

11. The method of claim 10, further comprising the steps of:

calculating an erosion rate from the total displacement of the process kit in the Z direction and the number of device substrates processed.

12. The method of claim 11, further comprising the steps of:

storing the erosion rate in a database.

13. The method of claim 9, wherein the sensor is a capacitive sensor.

14. The method of claim 13, wherein the capacitive sensor is a self-referencing capacitive sensor.

15. The method of claim 14, wherein the capacitive sensor comprises a first pad and a second pad, and wherein the current supplied to the first pad has an output phase that is 180 degrees out of phase with the output phase of the current supplied to the second pad.

Background

Embodiments relate to the field of semiconductor manufacturing, and more particularly, to methods and apparatus for measuring the position and erosion of a moving process kit.

Background

In the processing of a substrate, such as a semiconductor wafer, the substrate is placed on a support surface (e.g., an electrostatic chuck (ESC)) in a process chamber. Generally, a process kit is placed around a support surface to provide desired processing characteristics during substrate processing. For example, a process kit may be used to help shape the plasma in the plasma chamber to provide a more uniform process across the wafer. As such, it is often necessary to control the positioning of the top surface of the process kit relative to the top surface of the substrate being processed to achieve the desired processing results.

After the process kit is installed, various tests (such as etch rate tests or particle tests) may be implemented to confirm that the process kit is properly positioned relative to the processed substrate. However, such tests are expensive and may take hours to complete. Also, the process kit may be eroded during processing of the substrate. As such, the process kit may need to be adjusted to reset the relationship between the substrate surface and the top surface of the process kit. Currently, the erosion rate is not properly defined and adjustments can be made until after observable defects are found on the processed substrate.

Disclosure of Invention

Embodiments disclosed herein include a method of calibrating a process chamber. In an embodiment, the method comprises the steps of: the sensor wafer is placed onto a support surface in a processing chamber, wherein a process kit displaceable in the Z-direction is positioned around the support surface. In an embodiment, the method further comprises the steps of: a first gap distance between the sensor wafer and the process kit is measured with a sensor on an edge surface of the sensor wafer. In an embodiment, the method further comprises the steps of: the process kit is displaced in the Z-direction. In an embodiment, the method further comprises the steps of: an additional gap distance between the sensor wafer and the process kit is measured.

Embodiments disclosed herein include a method for measuring corrosion of a process kit. In an embodiment, the method comprises the steps of: the sensor wafer is placed on a support surface in a processing tool. In an embodiment, the method further comprises the steps of: a top surface of the process kit surrounding the support surface is aligned with a top surface of the sensor wafer using a sensor on the sensor wafer. In an embodiment, the method further comprises the steps of: the sensor wafer is removed from the support surface. In an embodiment, the method further comprises the steps of: one or more device substrates are processed in a processing tool. In an embodiment, the method further comprises the steps of: the sensor wafer is placed on a support surface. In an embodiment, the method further comprises the steps of: a gap distance between the sensor wafer and the process kit is measured with a sensor on an edge surface of the sensor wafer. In an embodiment, the method further comprises the steps of: the process kit is displaced in the Z-direction. In an embodiment, the method further comprises the steps of: the gap distance between the sensor wafer and the process kit is again measured. In an embodiment, the method further comprises the steps of: the operations of shifting the process kit and measuring the gap distance are repeated until successive gap distance measurements are equal to each other.

Embodiments disclosed herein include a sensor wafer. In an embodiment, the sensor wafer comprises: a substrate having a first surface and a second surface opposite the first surface, the first surface and the second surface being connected by an edge surface. In an embodiment, the sensor wafer further comprises: a plurality of sensors located around a perimeter of the substrate, wherein each of the sensors is an externally facing position sensor.

Drawings

Fig. 1A is a plan view of a sensor wafer having an edge sensor according to an embodiment.

Fig. 1B is a perspective view of a sensor wafer with an edge sensor according to an embodiment.

Fig. 2A is a partial cross-sectional view of a sensor wafer having an edge sensor according to an embodiment.

Figure 2B is a partial cross-sectional view of a sensor wafer with an edge sensor and an electric field protection shield according to an embodiment.

Figure 2C is a partial cross-sectional view of a sensor wafer with an edge sensor and a top surface notch according to an embodiment.

Figure 2D is a partial cross-sectional view of a sensor wafer having an edge sensor formed over a top surface of the sensor wafer according to an embodiment.

Figure 3A is a cross-sectional view of a sensor wafer measuring a gap distance between the sensor wafer and a fully recessed process kit according to an embodiment.

Fig. 3B is a cross-sectional view of the sensor wafer and process kit of fig. 3A after the process kit is vertically displaced by the lift pins by a first distance, in accordance with an embodiment.

Figure 3C is a cross-sectional view of the sensor wafer and the process kit of figure 3B after the process kit is vertically displaced a second distance such that a top surface of the process kit and a top surface of the sensor wafer are substantially coplanar, according to an embodiment.

FIG. 4 is a graph illustrating measured gap distances relative to a vertical shift of a process kit according to an embodiment.

Figure 5 is a cross-sectional view of a sensor wafer having an edge sensor above a top surface of the sensor wafer and a process kit elevated above the sensor wafer according to an embodiment.

Fig. 6 is a process flow diagram of a process for positioning a process kit relative to a sensor wafer according to an embodiment.

FIG. 7 is a process flow diagram of a process for determining an erosion rate of a process kit for a given processing operation, according to an embodiment.

FIG. 8 illustrates a block diagram of an exemplary computer system that can be used in conjunction with a process that includes the step of measuring the relationship of a sensor wafer relative to a process kit, in accordance with embodiments.

Detailed Description

Systems including sensor wafers with edge sensors and methods of using such sensor wafers to measure positioning of a process kit relative to a sensor wafer are described according to various embodiments. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent to one skilled in the art that embodiments may be practiced without these specific details. In other instances, well-known aspects have not been described in detail so as not to unnecessarily obscure the embodiments. Also, it is to be understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

As described above, to confirm that the process kit is properly positioned relative to the substrate, a plurality of substrates are processed in the processing tool to monitor the etch rate and/or run particle tests. Only after many substrates have been processed is it possible to confirm that the process kit is properly aligned to provide the desired processing results. This process requires hours of down time for the process tool and is expensive.

Accordingly, embodiments disclosed herein include a sensor wafer capable of directly measuring a process kit. In an embodiment, the sensor wafer may be used to confirm that the top surface of the process kit is substantially coplanar with the top surface of the sensor wafer. Because the sensor wafer may have substantially the same form factor as the wafer being processed in the chamber, the measurements of the process kit relative to the sensor wafer provide a sufficiently close approximation of the location of the production wafer relative to the process kit. As such, a single test procedure may be implemented after evacuation of the process tool to confirm that the process kit is positioned to the required tolerances with respect to the production wafers. Thus, the time to calibrate the processing tool is reduced and the throughput capacity of the processing tool may be increased.

Because process kits are used to manufacture semiconductor devices, the processing environment may cause erosion of the process kit and the desired relationship between the process kit and the device wafer may drift. Thus, embodiments include a sensor wafer that can also be used to detect the erosion rate of a process kit. After the sensor wafer is used to determine the erosion rate, the process kit can then be adjusted to account for the predicted erosion without recalibration of the process tool. In this manner, the throughput capacity of the processing tool may be increased.

Referring now to FIG. 1A, a sensor having multiple edge sensor regions 135 is shown according to an embodiment₁-135_nA plan view of the sensor wafer 110. In an embodiment, the edge sensor regions 135 are distributed around the perimeter of the sensor wafer 110. Each sensor region 135 includes one or more externally facing sensors. In an embodiment, the sensors in sensor region 135 may be used to measure the gap between the edge of sensor wafer 110 and a process kit (not shown) that surrounds sensor wafer 110. One or more sensors in the edge sensor region 135 can be capacitive sensors. In thatIn particular embodiments, edge sensor region 135 may include a self-referencing capacitive sensor.

In the illustrated embodiment, three edge sensor regions 135 are shown. However, it is to be understood that one or more edge sensor regions 135 can be used to determine when the top surface of the process kit is substantially coplanar with the top surface of the sensor wafer 110, as will be described in more detail below.

In an embodiment, each of edge sensor regions 135 can be communicatively coupled to a computation module 138 on sensor wafer 110 with traces 137. In embodiments, the calculation module 138 may include one or more of the following: a power source 132 (e.g., a battery), a processor/memory 134 (e.g., circuitry for implementing and/or storing measurements made with the edge sensor region 135, memory, etc.), and a wireless communication module 133 (e.g., bluetooth, WiFi, etc.). In an embodiment, calculation module 138 may be embedded in sensor wafer 110. Further, although shown as being central to sensor wafer 110, it is to be understood that computing module 138 may be located at any convenient location in sensor wafer 110.

Referring now to FIG. 1B, a perspective view of a sensor wafer 110 emphasizing details of an exemplary edge sensor region 135 is shown according to an embodiment. In an embodiment, the sensor wafer 110 can include a first surface 111 (e.g., a top surface), a second surface 113 (e.g., a bottom surface), and an edge surface 112 connecting the first surface 111 to the second surface 113. In an embodiment, edge sensor region 135 may be formed along edge surface 112.

In particular embodiments, edge sensor region 135 can include probes 141. The probe 141 (i.e., the probe in each edge sensor region) may be a self-referencing capacitive probe. That is, the output phase of the current supplied to the first probe 141 in the first edge sensor region 135 may be shifted by 180 degrees with respect to the output phase of the current supplied to the second probe 141 in the adjacent second edge sensor region 135. In this manner, a distance measurement from the edge surface 112 to the surface of the process kit (not shown) may be made without grounding the process kit. In the illustrated embodiment, edge sensor region 135 is shown with a single probe. However, in some embodiments, each edge sensor region 135 can include more than one probe 141. Although specific reference is made herein to self-referencing capacitive sensors, it is understood that embodiments disclosed herein include any suitable sensor technology (e.g., laser sensors, optical sensors, etc.).

Referring now to fig. 2A-2D, exemplary partial cross-sectional views of a sensor wafer 210 are shown, in accordance with various embodiments. In fig. 2A, the partial cross-sectional view depicts sensor region 235 substantially coplanar with edge surface 212. In an embodiment, the sensor region 235 emits an electric field 249 from the edge surface 212 such that the sensor can measure the gap between the edge surface 212 and the surface of the process kit.

Referring now to FIG. 2B, a partial cross-sectional view of a sensor wafer 210 having an electric field protective barrier 247 is shown, in accordance with an embodiment. In an embodiment, the electric field protection shield 247 may be a conductive layer formed between the bottom surface 213 of the sensor wafer 210 and the edge sensor region 235. The electric field 249 of the edge sensor region 235 can be modified by the electric field protection shield 247. Specifically, the electric field shield 247 can modify the electric field 249 of the edge sensor region 235 such that the electric field extends laterally away from the edge surface 212 toward the process kit. Thus, the electric field protection shield 247 prevents the sensors in the edge sensor region 235 from detecting objects below the sensor wafer 210 that may provide erroneous readings.

Referring now to fig. 2C, a partial cross-sectional view of sensor wafer 210 with top surface recesses 248 is shown, in accordance with an embodiment. In an embodiment, top surface recess 248 may be formed into first surface 211 proximate to sensor region 235. Top surface recess 248 may be made to prevent the sensor of sensor region 235 from sensing top surface 211 and providing an erroneous reading. In an embodiment, the top surface recess 248 may extend back a distance R. For example, distance R may be approximately equal to the maximum sensing distance of edge sensing region 235. In embodiments, the distance R may be 2.0mm or less, or 1.0mm or less.

Referring now to fig. 2D, a partial cross-sectional view of a sensor wafer 210 having a sensor region 235 formed over a first surface 211 of the sensor wafer 210 is shown, in accordance with an embodiment. Positioning sensor region 235 above sensor wafer 210 can be beneficial when it is desired to position the top surface of the process kit above the top surface of the device wafer. In an embodiment, sensor region 235 may have a thickness T that does not significantly alter the form factor of sensor wafer 210. For example, the thickness T may be less than 5mm, less than 2mm, less than 1mm, or less than 0.5 mm. Thus, the sensor wafer 210 can still pass through any load lock chambers in the processing tool.

Referring now to fig. 3A-3C, a series of cross-sectional views depicts a process for calibrating a process tool such that the top surface 361 of the process kit 360 is substantially coplanar with the first (i.e., top) surface 311 of the sensor wafer 310.

Referring now to FIG. 3A, a cross-sectional view of a portion of a sensor wafer 310 supported by a support surface 322 is shown, according to an embodiment. In an embodiment, sensor wafer 310 may be any sensor wafer having one or more edge sensor regions 335. For example, any of the sensor wafers described above with respect to fig. 1A-1D may be used in accordance with various embodiments. In the particular embodiment illustrated in fig. 3A, sensor wafer 310 includes an edge sensor region 335 and an electric field-shielding baffle 347, although embodiments are not limited to such configurations. In an embodiment, the sensor wafer 310 may have a form factor substantially similar to that of a wafer to be processed in a processing tool. For example, the sensor wafer 310 may have a diameter of 300mm and a thickness of less than 1 mm. In an embodiment, the support surface 322 may be an electrostatic chuck (ESC) or any other suitable surface for supporting and securing the sensor wafer 310.

In an embodiment, the support surface 322 may be surrounded by a process kit support 350 on which the process kit 360 rests. The support surface 322 may include a plurality of lift pins 352 disposed into openings 353 in the process kit support 350. In an embodiment, the lift pins 352 may be below the process kit 360. Upon extending the lift pins 352 with an actuator (not shown), the process kit is displaced in the Z-direction.

In fig. 3A, the lift pins 352 are fully retracted such that the process kit rests fully on the process kit support surface 350. In such embodiments, the top surface 361 of the process kit 360 may be below the top surface 311 of the sensor wafer 310. Thus, as the edge sensor region 335 senses outward toward the process kit 360, the edge sensor region detects a first point 371 on the top surface 361 of the process kit 360. In an embodiment, the first point 371 may be a first distance V from the inner surface 362 of the process kit 360₁。

Referring now to FIG. 3B, a lift pin is extended and the process kit 360 is raised in the Z direction by a distance D, according to an embodiment₁Followed by a partial cross-sectional view. As shown, the edge sensor region 335 now senses a second point 372 on the top surface 361 of the process kit 360. In an embodiment, the second point 372 may be a second distance V from an inner edge of the process kit 360₂. As will be understood by those skilled in the art, the process kit 360 is shifted in the Z-direction by a distance D₁So that the second distance V₂Is less than the first distance V shown in FIG. 3A₁. That is, the second point 372 is closer to the inner surface 362 of the process kit 360 than the first point 371.

Referring now to FIG. 3C, shifting the process kit by a second distance D in the Z-direction is shown according to an embodiment₂Followed by a partial cross-sectional view. As shown, displacement D₂Such that the top surface 361 of the process kit 360 is substantially coplanar with the top surface 311 of the sensor wafer. At this point, the edge sensor region 335 begins to measure the true gap G between the edge surface 312 of the sensor wafer 310 and the edge surface 362 of the process kit 360. Since the field of view of the edge sensor region 335 is completely blocked by the process kit 360, subsequent readings from the edge sensor region 335 will be substantially consistent as the process kit is further shifted in the Z-direction.

For example, FIG. 4 shows a graph of gap measurements relative to process kit displacement in the Z-direction. As shown in the drawings, the above-described,at D in the process kit 360₀When (i.e., when the process kit 360 is resting on the process kit support surface 350, as shown in FIG. 3A), the measured gap is equal to the true gap G plus the first distance V₁. At the process kit 360 by a displacement distance D₁(i.e., as shown in FIG. 3B), the measured gap is equal to the true gap G plus the second distance V₂. At the process kit 360 by a displacement distance D₂(i.e., as shown in fig. 3C), the measured gap is equal to the true gap G. Subsequent measurement (e.g., D)_n) The true gap G will be maintained because the inner surface 362 of the process kit 360 is substantially vertical and the edge sensor "sees" an unchanged surface as the process kit advances further in the Z direction. As used herein, it is understood that the sensor may not literally "see" the surface. For example, where a capacitive sensor is utilized (such as those described herein), voltage measurements of the conductive pads of the sensor may be correlated to the distance between the "seen" surface and the sensor. Once successive gap measurements return the same value (i.e., when the slope of the line of gap measurement distances relative to process kit displacement is zero), it can be inferred that the displacement (D) of the first instance of repeated measurements is a displacement where the top surface of the sensor wafer 310 is substantially coplanar with the top surface 361 of the process kit 360.

The edge sensor region can be placed over a first (i.e., top) surface of the sensor wafer when the top surface of the process kit needs to be over the top surface of the device wafer. Such an embodiment is shown in fig. 5. As shown, sensor region 535 is placed over first surface 511 of sensor wafer 510. Thus, the sensor region 535 does not "see" the inner surface 562 of the process kit 560 until the process kit 560 is displaced a distance D such that the top surface 561 of the process kit 560 is above the top surface 511 of the sensor wafer.

Referring now to fig. 6, a process flow diagram of a process 680 for aligning a top surface of a process kit with a top surface of a sensor wafer is shown in accordance with an embodiment.

In an embodiment, process 680 may begin at operation 681, which includes the steps of: the sensor wafer is placed on a support surface with a displaceable process kit surrounding the support surface. In embodiments, the sensor wafer may be any sensor wafer, such as those described herein that include one or more edge sensor regions. In an embodiment, the sensor wafer may have substantially the same form factor as a wafer processed in the processing tool. As such, the sensor wafer may be placed on a support surface (e.g., an electrostatic chuck) with a wafer handling robot. In an embodiment, the process kit may rest on a process kit support surface. The process kit support surface can include a plurality of lift pins for displacing the process kit in the Z-direction.

In an embodiment, process 680 may continue with operation 682, which includes the following steps: a first gap distance between the sensor wafer and the process kit is obtained with an edge sensor of the sensor wafer. In an embodiment, the edge sensor may be a self-referencing capacitive sensor. In an embodiment, the top surface of the process kit can be below the top surface of the sensor wafer. As such, the first gap distance may be obtained by sensing a first point along the top surface of the process kit instead of sensing the inner edge of the process kit.

In an embodiment, process 680 may continue with operation 683, which includes the following steps: the process kit is displaced a distance in the Z-direction. In an embodiment, the process kit may be displaced in the Z-direction with lift pins in the process kit support surface.

In an embodiment, process 680 may continue with operation 684, which includes the steps of: an additional gap distance between the sensor wafer and the process kit is obtained with an edge sensor.

In an embodiment, process 680 may continue with operation 685, which includes the steps of: the last two measured gap distances are compared. In embodiments where the last two measured gap distances are different, process 680 may repeat operations 683-685. For example, process 680 may repeat the following operations: displacing the process kit in the Z-direction; obtaining an additional gap distance; and comparing the last two measured gap distances (e.g., comparing the third gap distance to the second gap distance, comparing the fourth gap distance to the third gap distance, etc.). In embodiments where the last two measured gap distances are the same, process 680 may end because the top surface of the process kit is now substantially coplanar with the top surface of the sensor wafer.

Referring now to FIG. 7, a process flow diagram of a process 780 for determining an amount of erosion of a process kit is shown in accordance with an embodiment.

In an embodiment, the process 780 begins with operation 781, which includes the steps of: the method includes placing a sensor wafer on a support surface, and aligning a top surface of a process kit with a top surface of the sensor wafer using an edge sensor of the sensor wafer. The process for aligning the top surface of the process kit with the top surface of the sensor wafer may be substantially similar to the process 680 described above with respect to fig. 6.

In an embodiment, the process 780 may proceed to operation 782, which includes the steps of: the sensor wafer is removed from the support surface. In an embodiment, the sensor wafer may be removed with a wafer handling robot or the like.

In an embodiment, the process 780 may proceed to operation 783, which includes the steps of: a plurality of wafers are processed on a support surface. In an embodiment, the step of processing the plurality of wafers may include any semiconductor manufacturing process. For example, the process may include an etching process. In an embodiment, the processing may result in eroding the process kit. In embodiments, the plurality of wafers may include tens of wafers, hundreds of wafers, or thousands of wafers.

In an embodiment, the process 780 may proceed to operation 784, which includes the steps of: the sensor wafer is placed on a support surface. In an embodiment, the sensor wafer may be the same sensor wafer used in operation 781. However, it is to be understood that different sensor wafers may also be used in some embodiments.

In an embodiment, the process 780 may proceed to operation 785, which includes the steps of: a first gap distance between the sensor wafer and the process kit is obtained with an edge sensor of the sensor wafer. In an embodiment, the erosion may be such that the top surface of the process kit is below the top surface of the sensor wafer. Thus, the first gap distance may sense the top surface of the process kit rather than the inner surface of the process kit.

In an embodiment, the process 780 may proceed to operation 786, which includes the steps of: the process kit is displaced a distance in the Z-direction. In an embodiment, the process kit may be displaced with lift pins in the process kit support surface.

In an embodiment, the process 780 may proceed to operation 787, which includes the steps of: an additional gap distance between the sensor wafer and the process kit is obtained with an edge sensor.

In an embodiment, the process 780 may proceed to operation 788, which includes the steps of: the last two measured gap distances are compared. In embodiments where the last two measured gap distances are different, the process 780 may repeat operations 786-. For example, the process 780 may repeat the following operations: displacing the process kit in the Z-direction; obtaining an additional gap distance; and comparing the last two measured gap distances (e.g., comparing the third gap distance to the second gap distance, comparing the fourth gap distance to the third gap distance, etc.).

In embodiments where the last two measured gap distances are the same, the process 780 may proceed to operation 789, which includes the steps of: the erosion rate is calculated. In an embodiment, the erosion rate may be calculated by: a total displacement of the process kit in the Z direction is determined and divided by the number of wafers of the plurality of wafers processed in operation 783. Thus, the erosion rate can be expressed in terms of erosion distance per unit number of processed wafers. In additional embodiments, the erosion rate may be calculated by: the total displacement of the process kit is determined and divided by the time it takes to process the plurality of wafers. In such embodiments, the erosion rate may be expressed as an erosion rate per unit of treatment minutes.

In embodiments, the erosion rate may be stored in a database for future use. For example, the erosion rate may be stored and subsequent processing may automatically shift the process kit to account for the expected erosion. As such, further measurements of the sensor wafer may not be necessary and the processing tool throughput capacity may be increased.

Referring now to FIG. 8, a block diagram of an exemplary computer system 860 of the processing tool is illustrated, according to an embodiment. In an embodiment, one or more processes, such as processes 680 and 780, may be implemented using computer system 860. In an embodiment, the computer system 860 is coupled to a processing tool and controls processing in the processing tool. The computer system 860 may be connected (e.g., networked) to other machines in a network 861 (e.g., a Local Area Network (LAN), an intranet, an extranet, or the internet). Computer system 860 may operate in the capacity of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. Computer system 860 may be a Personal Computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated with respect to the computer system 860, the term "machine" shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein.

The computer system 860 may include a computer program product or software 822 having a non-transitory machine-readable medium having stored thereon instructions, which may be used to program the computer system 860 (or other electronic devices) to perform a process according to an embodiment. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., computer) readable storage medium (e.g., read only memory ("ROM"), random access memory ("RAM"), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (e.g., electrical, optical, acoustical, or other form of propagated signals (e.g., infrared signals, digital signals, etc.)), and so forth.

In an embodiment, computer system 860 includes a system processor 802, a main memory 804 (e.g., Read Only Memory (ROM), flash memory, Dynamic Random Access Memory (DRAM) (e.g., synchronous DRAM (sdram) or Rambus DRAM (RDRAM)), etc.), a static memory 806 (e.g., flash memory, Static Random Access Memory (SRAM), etc.), and a secondary memory 818 (e.g., a data storage device) that communicate with each other via a bus 830.

The system processor 802 represents one or more general-purpose processing devices such as a micro-system processor, central processing unit, or the like. More specifically, the system processor may be a Complex Instruction Set Computing (CISC) microsystem processor, a Reduced Instruction Set Computing (RISC) microsystem processor, a Very Long Instruction Word (VLIW) microsystem processor, a system processor implementing other instruction sets, or a system processor implementing a combination of instruction sets. The system processor 802 may also be one or more special-purpose processing devices such as an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a digital signal system processor (DSP), network system processor, or the like. System processor 802 is configured to execute processing logic 826 for performing the operations described herein.

The computer system 860 may further include a system network interface device 808 for communicating with other devices or machines. The computer system 860 may also include a video display unit 810 (e.g., a Liquid Crystal Display (LCD), a light emitting diode display (LED), or a Cathode Ray Tube (CRT)), an alphanumeric input device 812 (e.g., a keyboard), a cursor control device 814 (e.g., a mouse), and a signal generation device 816 (e.g., a speaker).

The secondary memory 818 may include a machine-accessible storage medium 831 (or more specifically a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software 822) embodying any one or more of the methodologies or functions described herein. The software 822 may also reside, completely or at least partially, within the main memory 804 and/or within the system processor 802 during execution thereof by the computer system 860, the main memory 804 and the system processor 802 also constituting machine-readable storage media. The software 822 may further be transmitted or received over a network 861 via the system network interface device 808.

While the machine-accessible storage medium 831 is shown in an exemplary embodiment to be a single medium, the term "machine-readable storage medium" should also be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term "machine-readable storage medium" shall also be taken to include any medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies. The term "machine-readable storage medium" shall accordingly be taken to include, but not be limited to, solid-state memories and optical and magnetic media.

In the foregoing specification, specific exemplary embodiments have been described. It will be apparent that various modifications can be made to these embodiments without departing from the scope of the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.