阅读说明：本技术 金属囊封光电阴极电子发射器 (Metal encapsulated photocathode electron emitter ) 是由 G·德尔加多 K·艾奥凯密迪 F·希尔 G·洛佩兹 R·F·加西亚 于 2019-09-17 设计创作，主要内容包括：本发明揭示一种光电阴极结构,其可包含Cs2Te、CsKTe、CsI、CsBr、GaAs、GaN、InSb、CsKSb或金属中的一或多者,所述光电阴极结构在外表面上具有保护膜。所述保护膜包含钌、镍、铂、铬、铜、金、银、铝中的一或多者或其合金。所述保护膜可具有从1nm到10nm的厚度。所述光电阴极结构可用于如扫描电子显微镜的电子束工具中。(A photocathode structure may include one or more of Cs2Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or a metal, having a protective film on an outer surface. The protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof. The protective film may have a thickness of from 1nm to 10 nm. The photocathode structure may be used in e-beam tools such as scanning electron microscopes.)

1. An electron emitter, comprising:

a photocathode structure comprising Cs₂One or more of Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or a metal; and

a protective film disposed on an outer surface of the photocathode structure, wherein the protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof.

2. The electron emitter of claim 1, further comprising:

a substrate;

a second protective film between the substrate and the photocathode structure, wherein the second protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof.

3. The electron emitter of claim 2, wherein the substrate is quartz, sapphire, UV fused silica, CaF₂Or MgF₂One or more of (a).

4. The method of claim 1Further comprising a substrate disposed on a side of the photocathode structure opposite the outer surface, wherein the protective film encapsulates the photocathode structure and is disposed between the photocathode structure and the substrate, and wherein the substrate is quartz, sapphire, UV fused silica, CaF₂Or MgF₂One or more of (a).

5. The electron emitter of claim 4, further comprising a voltage source that applies a voltage to the protective film.

6. The electron emitter of claim 1, wherein the photocathode structure comprises Cs₂Te or CsKTe and the protective film comprises one or more of ruthenium, nickel, or platinum.

7. The electron emitter of claim 1, wherein the protective film comprises nickel.

8. The electron emitter of claim 1, wherein the photocathode structure is configured to operate in a transmissive or reflective mode.

9. The electron emitter of claim 1, further comprising a voltage source that applies a voltage to the protective film.

10. The electron emitter of claim 1, wherein the protective film is transparent to UV wavelengths.

11. The electron emitter according to claim 1, wherein the protective film has a thickness from 1nm to 10 nm.

12. The electron emitter of claim 1, wherein the protective film has a porosity of less than or equal to 25%.

13. The electron emitter of claim 1, wherein the protective film has a packing density greater than or equal to 0.92.

14. An electron beam tool comprising the electron emitter of claim 1, wherein the electron beam tool comprises a detector that receives electrons generated by the electron emitter and reflected from a surface of a wafer.

15. A method, comprising:

providing a composition comprising Cs₂A photocathode structure of one or more of Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb or metal;

depositing a protective film on an outer surface of the photocathode structure, wherein the protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof.

16. The method of claim 15, wherein the depositing comprises ion sputtering, magnetron sputtering, or atomic layer deposition.

17. A method, comprising:

providing a photocathode structure, wherein the photocathode comprises Cs₂One or more of Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or a metal, and a protective film disposed on an outer surface of the photocathode structure, wherein the protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof; and

an electron beam is generated from the photocathode structure as photons are directed at the photocathode structure.

18. The method of claim 17, further comprising performing a plasma cleaning of the photocathode structure.

19. The method of claim 17, wherein the photocathode structure generates the electron beam in a transmissive mode.

20. The method of claim 17, wherein the photocathode structure generates the electron beam in a reflective mode.

Technical Field

The present disclosure relates to a protective film for an electron emitter.

Background

The evolution of the semiconductor manufacturing industry places higher demands on yield management and, in particular, metrology and inspection systems. The critical dimension is continuously shrinking and the industry needs to reduce the time to achieve high yield, high value production. Minimizing the total time from the detection of a yield problem to the resolution of the problem determines the return on investment of the semiconductor manufacturer.

The fabrication of semiconductor devices, such as logic and memory devices, typically includes processing a semiconductor wafer using a number of manufacturing processes to form various features and multiple levels of semiconductor devices. For example, photolithography is a semiconductor manufacturing process that involves transferring a pattern from a reticle to a photoresist disposed on a semiconductor wafer. Additional examples of semiconductor manufacturing processes include, but are not limited to, Chemical Mechanical Polishing (CMP), etching, deposition, and ion implantation. Multiple semiconductor devices may be fabricated in an arrangement on a single semiconductor wafer and then separated into individual semiconductor devices.

Electron beams are used in several different applications during semiconductor manufacturing. For example, an electron beam may be modulated and directed onto an electron sensitive resist on a semiconductor wafer, mask, or other workpiece to create an electron pattern on the workpiece. Electron beams may also be used to inspect wafers by, for example, detecting electrons that are emitted or reflected from the wafer to detect defects, anomalies, or undesirable objects.

These inspection processes are used at various steps during the semiconductor manufacturing process to facilitate higher yields and therefore higher profits in the manufacturing process. Inspection is always an important part of the manufacture of semiconductor devices such as Integrated Circuits (ICs). However, as semiconductor device sizes decrease, inspection becomes more important for successful fabrication of acceptable semiconductor devices, as smaller defects can lead to device failure. For example, as the size of semiconductor devices decreases, detection of defects of decreasing size has become necessary because even relatively small defects can cause undesirable aberrations in the semiconductor devices.

Photocathodes have also been used to generate electron beams. A single beam of light incident on the photocathode system may produce a single electron beam with high brightness capable of delivering a high electron current density. For example, base photoelectron emitters have been used as photocathode emitters in the UV spectral range. These photocathodes degrade due to the vacuum environment and exposure to heavy Deep Ultraviolet (DUV) photons. There is no explicit way to prevent this from happening during the lifetime of the system.

Photocathode electron emitters typically do not have a protective coating to protect them from oxidation or carbon build-up from the vacuum environment. Some have protective cap layers, but existing protective cap layers on photocathodes are not robust to cleaning. Thus, these capping layers do not protect the photocathode electron emitter during operation.

Accordingly, there is a need for improved photocathode electron emitters.

Disclosure of Invention

In a first embodiment, an electron emitter is provided. The electron emitter includes: a photocathode structure comprising one or more of Cs2Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or a metal; and a protective film disposed on an outer surface of the photocathode structure. The protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof.

In an example, a voltage source supplies a voltage to the protective film.

The electron emitter may further include a second protective film between the substrate and the photocathode structure. The second protective film may comprise one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof. In an example, the second protective film comprises one or more of ruthenium, nickel, or platinum. The substrate may be quartz, sapphire, UV fused silica, CaF₂Or MgF₂One or more of (a).

The electron emitter may further include a substrate disposed on a side of the photocathode structure opposite the outer surface. The protective film may encapsulate the photocathode structure and be disposed between the photocathode structure and the substrate. The substrate may be quartz, sapphire, UV fused silica, CaF₂Or MgF₂One or more of (a). A voltage source may apply a voltage to the protective film.

In an example, the photocathode structure includes Cs₂Te or CsKTe and the protective film comprises one or more of ruthenium, nickel, or platinum.

In an example, the protective film comprises nickel.

The photocathode structure may be configured to operate in a transmissive or reflective mode.

The protective film may be transparent to UV wavelengths.

The protective film may have a thickness of from 1nm to 10 nm.

The protective film can have a porosity of less than or equal to 25%.

The protective film can have a packing density greater than or equal to 0.92.

An e-beam tool may comprise an example of the electron emitter of the first embodiment. The electron beam tool includes a detector that receives electrons generated by the electron emitter and reflected from a surface of a wafer.

In a second embodiment, a method is provided. Providing a composition comprising Cs₂A photocathode structure of one or more of Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or metals. At the photocathode junctionA protective film is deposited on the outer surface of the structure. The protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof. The deposition may comprise ion sputtering, magnetron sputtering, or atomic layer deposition.

In a third embodiment, a method is provided. A photocathode structure is provided. The photocathode comprises Cs₂One or more of Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or a metal, and a protective film disposed on an outer surface of the photocathode structure. The protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof. An electron beam is generated from the photocathode structure as photons are directed at the photocathode structure.

Plasma cleaning of the photocathode structure may be performed.

The photocathode structure may generate the electron beam in a transmissive mode or a reflective mode.

Drawings

For a fuller understanding of the nature and objects of the present disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view of an embodiment of an electron emitter according to the present disclosure;

FIG. 2 shows the test results of the stability of Pt/CsKTe/Ni photocathodes;

FIG. 3 is a flow chart of a method embodiment according to the present disclosure;

FIG. 4 is a flow chart of another method embodiment according to the present disclosure;

FIG. 5 is a block diagram of an embodiment of a system according to the present disclosure; and

fig. 6 shows the test results of photocurrent.

Detailed Description

Although claimed subject matter will be described in terms of certain embodiments, other embodiments (including embodiments that do not provide all of the benefits and features set forth herein) are also within the scope of the present disclosure. Various structural, logical, process step, and electrical changes may be made without departing from the scope of the present disclosure. Accordingly, the scope of the disclosure is defined only by reference to the appended claims.

High quantum efficiency photocathodes are disclosed that can be operated in lower vacuum conditions. Ruthenium, ruthenium alloys, platinum alloys, nickel alloys, chromium alloys, copper alloys, combinations thereof, or other metals may be used in the protective film to encapsulate one or more surfaces of the photocathode. These other metals may be, for example, gold, silver or aluminum. Photocathodes are subject to vacuum conditions to cause degradation of field emission performance. To maintain high electron current stability and lifetime, the photocathode may be fully or partially encapsulated with a protective film. The protective film makes the photocathode resistant to oxidation and carbon accumulation. The protective film also has a relatively low sputtering yield and can withstand erosion by ions. In addition, the protective film may provide advantages over the use of the photocathode itself. Metals may also have lower emissivity than semiconductors and insulators. Thus, the use of a protective film may provide higher current stability due to the properties of one or more metals, provide improved lifetime, provide lower emissivity, and may enable operation at lower vacuum. Low emissivity can be beneficial when focusing the electron beam to a small spot.

Photocathodes are electron sources that emit photons when the photocathode is exposed to a light source in either a transmissive or reflective mode. The photocathode structure may be a bulk material, a film, or a series of films deposited on a substrate. The wavelength(s) of light may be selected to optimize the amount of emission current and the spread of energy of the emitted electrons. The current generated by the photocathode may be more stable than the current generated by the cold field emitter. Many materials are available for photoemission, including silicon, silicon with a metal coating, or alkali metal halides. For example, Cs₂The Te and CsKTe photocathodes have high quantum efficiency to have light in the DUV range. Other photocathode materials that can be used include CsI, CsBr, GaAs, GaN, InSb, CsKSb, or metals. Other photocathode materials are possible.

FIG. 1 is a cross-sectional view of an embodiment of an electron emitter 100. The electron emitter 100 includes a photocathode structure 101. The photocathode structure 101 may include Cs₂Te and CsKTe. The photocathode structure 101 may also comprise other semiconductor or metal photocathode materials. Photocathode structure101 may comprise planar features, but other shapes are possible.

The protective film 102 is disposed on an outer surface 105 of the photocathode structure 101. The protective film 102 includes one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or an alloy thereof. For example, the protective film 102 may be ruthenium or a ruthenium alloy, such as an alloy of ruthenium and platinum. Protective film 102 makes photocathode structure 101 more robust in the presence of a highly electric film and more robust to ion sputtering, plasma, or other cleaning techniques.

Under ultra-high vacuum conditions, a carbon layer may be grown on the surface of the electron emitter 100 during electron beam emission. Also, oxidation of the surface of the electron emitter 100 occurs over time even in ultra-high vacuum conditions. Carbon or oxidation can affect the photocathode performance. The protective film 102 may protect the surface of the electron emitter (e.g., the outer surface 105 of the photocathode structure 101) from oxidation and carbon build-up. This is beneficial to the lifetime of the electron emitter 100.

The electron emitter 100 may further include a substrate 104. The substrate 104 may be quartz, sapphire, UV fused silica, CaF₂Or MgF₂One or more of (a). Other materials for the substrate are possible.

In the example, a 5 μm nickel protective film 102 is used with the photocathode structure 101.

A second protective film 103 may be formed between the substrate 104 and the photocathode structure 101. The second protective film 103 may be on the surface of the photocathode structure 101 opposite to the protective film 102. The second protective film 103 contains one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or an alloy thereof. For example, the second protective film 103 may be ruthenium or a ruthenium alloy, such as an alloy of ruthenium and platinum.

The second protective film 103 may be different from the protective film 102. In an example, the second protective film 103 can be a material with low absorption and acceptable coverage, electrical uniformity, and plasma effects. The protective film 102 may have a work function lower than that of the second protective film 103.

In the example, the protective film 102 and the second protective film 103 are portions of the same protective film that partially or completely encapsulate the photocathode structure 101. A substrate 104 is disposed on a side of the photocathode structure 101 opposite the outer surface 105. A protective film and a second protective film 103 are disposed between the photocathode structure 101 and the substrate 104.

The voltage source 106 may apply a voltage to the protective film 102 or the second protective film 103. Introducing a voltage to the protective film 102 and/or the second protective film 103 can provide control of electron migration to a desired surface. For example, if the second protective film 103 on the backside of the electron emitter 100 is positively charged, electrons may be made to migrate to the exit surface to enhance electron emission.

The protective film 102 or the second protective film 103 may have a thickness from 1nm to 10nm, including all values to 0.1nm and ranges therebetween. This thickness may be measured from the outer surface of the photocathode structure 101 or another layer on which the protective film 102 or the second protective film 103 is disposed. The optimal thickness of the protective film 102 may be configured for optimal electron emission. Larger thicknesses, while feasible, may affect efficiency.

The thickness of the protective film 102 may depend on the electron emitter 100 extractor configuration and the wavelength used for photoelectron emission. For example, the thickness may vary from 1mm to 2mm based on the electron emitter 100 extractor configuration. If the thickness is too large, it will absorb all the light and/or will not allow electrons to escape easily due to the increased work function. Since the protective film 102 generally provides a protective function, it may be thick enough to protect the photocathode structure 101 without affecting performance. The protective film 102 may also supply electrons, and thus the thickness may vary with the wavelength of light for electron generation. For example, the thickness of the protective film 102 may be optimized for a 266nm wavelength such that the work function is minimized and the coverage on the surface is uniform.

The thickness of the substrate 104 may also be optimized for a particular wavelength. The thickness of the substrate 104 may be selected to optimize electrical continuity while minimizing light absorption.

The thickness of the protective film 102 may also be configured to be optimized for optimal light transmission and maximum quantum efficiency for a given wavelength to produce optimal electron emission. As the thickness of the protective film 102 increases, it becomes more difficult for electrons to escape to vacuum, and thus the quantum efficiency decreases. The exact thickness may depend on the photocathode extractor configuration and the wavelength used for photoelectron emission. Optimizing the wavelength minimizes the energy spread.

The protective film 102 may not have a pinhole in at least one emission region of the photocathode structure 101. The second protective film 103 may not have a pinhole. The protective film 102 or the second protective film 103 may have a porosity of less than or equal to 25%. If the porosity is greater than 25%, protection may be compromised. The protective film 102 or the second protective film 103 may have a packing density of greater than or equal to 0.92. A packing density of less than 0.92 may compromise protection. The property of the protective film 102 may be different from that of the second protective film 103.

The protective film 102 or the second protective film 103 may be deposited by ion or magnetron sputtering, Atomic Layer Deposition (ALD), or by other methods that provide a dense, pinhole-free, uniform protective film 102. The following equation may use refractive index to define and measure porosity (P).

In the previous equation, n_fIs the refractive index of the protective film 102 and n_bIs the refractive index of the material. The Packing Density (PD) of the film was defined as the average film density (ρ) using the following equation_f) To volume density (p)_B) The ratio of.

PD＝ρ_f/ρ_B

The correlation between the film refractive index and its packing density can be expressed using the following equation.

The protective film 102 may be free of bubbles and inclusions in at least one emission region. The second protective film 103 may be free of bubbles and inclusions. For example, the protective film 102 or the second protective film 103 may contain flaws having only a diameter or length dimension of less than 1 nm.

The protective film 102 may have less than 10 in the emission area⁴And (c) impurities. ImpuritiesMay contain carbon, oxides, oxygen as dissolved gas, sodium or potassium.

The protective film 102 may be robust to electron field emission, in the presence of high electric fields, to ion sputtering, and to plasma or other cleaning methods. Oxidation and/or carbon may be removed from the protective film 102 without damaging the protective film 102. For example, the protective film 102 may be cleaned to the atomic level by molecular hydrogen, hydrogen plasma, or other plasma.

In addition to allowing cleaning without damaging the protective film 102, the protective film 102 may also be resistant to oxidation and carbon contamination. Ruthenium may be able to break up gas molecules falling on its surface or prevent such gas molecules from adhering to its surface. These molecules are able to distort the extraction field on the surface of the electron emitter 100 and result in enhanced emission due to the mobility and residence time of the molecules on the surface, which translates into noise in the beam. Thus, the protective film 102 may be self-cleaning.

The photocathode structure 101, if coated with the protective film 102, may have a smoother surface and lower emissivity. The protective film 102 on the photocathode structure 101 may control electromigration to a desired surface, for example, during application of a voltage. Electromigration may be controlled using a protective film 102 on one surface of the photocathode structure 101 and a second protective film 103 on the opposite surface of the photocathode structure 101. The protective film 102 may also provide improved angular spread of the electron beam. A smoother protective film 102 may provide this improved angular spread.

The use of the protective film 102 may enable operation of the electron emitter 100 at higher pressures. The photocathode may typically be in the range of about 10^-11And (4) carrying out underpinning operation. With the protective film 102, the electron emitter 100 may be capable of about 10^-9And (4) carrying out underpinning operation.

The protective film 102 is transparent to UV wavelengths. This may enable operation of the electron emitter 100 in both a transmissive mode and a reflective mode. The transmissive mode illuminates the surface of the photocathode structure 101 opposite the outer surface 105, e.g., through the substrate 104. The reflective mode illuminates the outer surface 105 of the photocathode structure 101.

Embodiments of the electron source 100 can be used as an electron source in reticle and wafer inspection systems. For example, embodiments of the electron source 100 can be used as an electron source in an electron beam wafer or reticle inspection system using a single or multiple electron sources, an electron beam wafer or reticle review system using a single or multiple electron sources, or an electron beam wafer or reticle metrology system using a single or multiple electron sources. Embodiments of the electron source 100 can also be used in systems that use single or multiple electron sources to generate x-rays in wafer or reticle metrology, review or inspection.

FIG. 2 shows the results of testing the stability of Pt/CsKTe/Ni photocathodes. The extraction current is plotted over a period of about six hours. Most of the noise seen in fig. 2 is caused by the laser light. Figure 2 demonstrates that a photocathode with a protective film, such as protective film 102, will have higher stability and lifetime.

Fig. 6 shows test results of photocurrent of the photocathode of fig. 2. Fig. 6 demonstrates that the photocurrent is relatively stable over long operating periods, which is an improvement over previous designs.

Fig. 3 is a flow chart of a method 200. At 201, providing a sample containing Cs₂A photocathode structure of one or more of Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or metals. In an example, the photocathode comprises Cs₂Te or CsKTe. At 202, a protective film is deposited on an outer surface of the photocathode structure. The protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof. In an example, the protective film comprises one or more of ruthenium, nickel, platinum, chromium, or copper. The protective film may be an embodiment of the protective film 102. The deposition may comprise ion sputtering, magnetron sputtering, or ALD. Deposition can provide desired film density, conformal properties, and pinhole defect levels.

Fig. 4 is a flow chart of a method 250. At 251, a photocathode structure is provided. The photocathode structure comprises Cs₂One or more of Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or a metal. The photocathode structure also includes a protective film disposed on an outer surface of the photocathode structure. The protective film comprises one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or alloys thereof. In an example, the photocathode structure includes Cs₂Te or CsKTe and the protective film contains ruthenium and nickelPlatinum, chromium or copper. The protective film may be an embodiment of the protective film 102. At 252, an electron beam is generated from the photocathode structure as photons are directed at the photocathode structure. Electron generation can be at about 10^-5Torr or less (e.g., 10)^-9Torr). The electron beam can be generated in a transmissive or reflective mode.

After generating the electron beam, a plasma clean of the photocathode structure may optionally be performed. Plasma cleaning may be used to remove oxidation and carbon from the surface. Plasma cleaning may use molecular hydrogen, hydrogen plasma, or other plasma cleaning to atomic level.

Fig. 5 is a block diagram of an embodiment of a system 300. The system 300 includes a wafer inspection tool (which includes an electron column 301) configured to generate an image of a wafer 304.

The wafer inspection tool includes an output acquisition subsystem including at least one energy source and a detector. The output acquisition subsystem may be an electron beam-based output acquisition subsystem. For example, in one embodiment, the energy directed to the wafer 304 includes electrons and the energy detected from the wafer 304 includes electrons. In this way, the energy source may be an electron beam source. In one such embodiment shown in fig. 5, the output acquisition subsystem includes an electron column 301 coupled to a computer subsystem 302. A chuck (not illustrated) may hold the wafer 304.

As also shown in fig. 5, the electron column 301 includes an electron beam source 303, the electron beam source 303 configured to generate electrons focused by the one or more elements 305 to the wafer 304. The electron beam source 303 may comprise an embodiment such as the electron source 100 of fig. 1. The one or more elements 305 may include, for example, a gun lens, an anode, a beam limiting aperture, a gate valve, a beam current selection aperture, an objective lens, and a scanning subsystem, all of which may include any such suitable elements known in the art.

Electrons (e.g., secondary electrons) returning from the wafer 304 may be focused by one or more elements 306 to a detector 307. One or more elements 306 may include, for example, a scanning subsystem, which may be the same scanning subsystem included in element(s) 305.

The electron column may also comprise any other suitable element known in the art.

Although the electron column 301 is shown in fig. 5 as being configured such that electrons are directed to the wafer 304 at an oblique angle of incidence and scattered from the wafer 304 at another oblique angle, the electron beam may be directed to the wafer 304 and scattered from the wafer 304 at any suitable angle. In addition, the electron beam-based output acquisition subsystem may be configured to generate images of the wafer 304 using multiple modes (e.g., using different illumination angles, collection angles, etc.). The multiple modes of the electron beam based output acquisition subsystem may differ in any image generation parameter of the output acquisition subsystem.

The computer subsystem 302 may be coupled to the detector 307 such that the computer subsystem 302 is in electronic communication with the detector 307 or other components of the wafer inspection tool. The detector 307 may detect electrons returning from the surface of the wafer 304, thereby forming an electron beam image of the wafer 304 using the computer subsystem 302. The electron beam image may comprise any suitable electron beam image. Computer subsystem 302 includes processor 308 and electronic data storage unit 309. Processor 308 may include a microprocessor, microcontroller, or other device.

It should be noted that fig. 5 is provided herein to generally illustrate the configuration of an electron beam-based output acquisition subsystem that may be used in the embodiments described herein. As typically performed when designing commercial output acquisition systems, the electron beam-based output acquisition subsystem arrangements described herein may be altered to optimize the performance of the output acquisition subsystem. Additionally, the systems described herein may be implemented using existing systems (e.g., by adding the functionality described herein to existing systems). For some such systems, the methods described herein may be provided as optional functionality of the system (e.g., in addition to other functionality of the system). Alternatively, the systems described herein may be designed as entirely new systems.

Computer subsystem 302 may be coupled to the components of system 300 in any suitable manner (e.g., via one or more transmission media, which may include wired and/or wireless transmission media) such that processor 308 may receive an output. The processor 308 may be configured to perform a number of functions using the output. The wafer inspection tool may receive instructions or other information from processor 308. The processor 308 and/or electronic data storage unit 309 optionally may be in electronic communication with another wafer inspection tool, wafer metrology tool, or wafer review tool (not illustrated) to receive additional information or send instructions.

Computer subsystem 302, other system(s), or other subsystem(s) described herein may be part of various systems, including a personal computer system, image computer, main computer system, workstation, network appliance, internet appliance, or other device. The subsystem(s) or system(s) may also include any suitable processor known in the art, such as a parallel processor. In addition, the subsystem(s) or system(s) may include a platform with high speed processing and software as a separate or networked tool.

Processor 308 and electronic data storage unit 309 may be disposed in or otherwise be part of system 300 or another device. In an example, the processor 308 and the electronic data storage unit 309 may be part of a separate control unit or in a centralized quality control unit. Multiple processors 308 or electronic data storage units 309 may be used.

In practice, processor 308 may be implemented by any combination of hardware, software, and firmware. Also, its functions as described herein may be performed by one unit, or divided among different components, each of which in turn may be implemented by any combination of hardware, software, and firmware. Program code or instructions implementing the various methods and functions by processor 308 may be stored in a readable storage medium, such as memory in electronic data storage unit 309 or other memory.

The system 300 of fig. 5 is but one example of a system that may use embodiments of the electron source 100 or embodiments of the method 250. Embodiments of the electron source 100 may be part of a defect review system, an inspection system, a metrology system, or some other type of system. Thus, embodiments disclosed herein describe some configurations that can be customized in several ways for systems with different capabilities more or less suited for different applications.

Each of the steps of the method may be performed as described herein. The method may also include any other step(s) that may be performed by the processor and/or computer subsystem(s) or system(s) described herein. The steps are performed by one or more computer systems, which may be configured in accordance with any of the embodiments described herein. Additionally, the above-described method may be performed by any of the system embodiments described herein.

While the present disclosure has been described with reference to one or more particular embodiments, it will be understood that other embodiments of the disclosure may be made without departing from the scope of the disclosure. Accordingly, the present disclosure is to be considered limited only by the following claims and the reasonable interpretation thereof.