Method and apparatus for dynamic sealing between zones of ultra-clean vacuum system

Abstract

An apparatus includes a vacuum chamber, a first assembly, a second assembly movable relative to the first assembly, and a gas injector. The vacuum chamber includes a first vacuum region and a second vacuum region. The first component is disposed in the first vacuum region at an interface with the second vacuum region. The second component is disposed at the interface in the second vacuum zone and spaced from the first component by a gap. The gas injector is configured to inject a buffer gas from at least one aperture in at least one of the first component and the second component into the gap between the first component and the second component. The buffer gas provides a dynamic seal between the first vacuum zone and the second vacuum zone during movement of the second component relative to the first component.

Description

Technical Field

[0001] The present disclosure relates to sealing devices for semiconductor inspection or metrology systems. Background Art

[0002] The evolution of the semiconductor manufacturing industry places increasing demands on yield management and, in particular, metrology and inspection systems. Critical dimensions continue to shrink, but the industry needs to reduce the time it takes to achieve high-yield, high-value production. Minimizing the total time from detecting a yield problem to fixing it determines the return on investment for semiconductor manufacturers.

[0003] The manufacture of semiconductor devices, such as logic and memory devices, typically includes processing a semiconductor wafer using a number of manufacturing processes to form the various features and multiple levels of the semiconductor devices. For example, photolithography is a semiconductor manufacturing process that involves transferring a pattern from a mask 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. An arrangement of multiple semiconductor devices manufactured on a single semiconductor wafer may be separated into individual semiconductor devices.

[0004] Inspection processes are used to detect defects on wafers at various steps during semiconductor manufacturing to facilitate higher yields and therefore higher profits for the manufacturing process. Inspection has always been an important part of manufacturing semiconductor devices, such as integrated circuits (ICs). However, as the size of semiconductor devices decreases, inspection becomes more important to the successful manufacture of acceptable semiconductor devices because smaller defects can cause the devices to fail. For example, as the size of semiconductor devices decreases, the detection of defects of reduced size has become necessary because even relatively small defects can cause undesired aberrations in semiconductor devices.

[0005] Some inspection processes need to be performed in a vacuum chamber to prevent external contaminants from entering the system. Certain components within the vacuum chamber need to be actuated for alignment reasons, which may use precise (e.g., sub-nanometer) accurate movement for one or more degrees of freedom. The actuators required to move these components can outgas volatile hydrocarbons, inorganic contaminants, and particles (collectively referred to herein as "contaminants"). This actuation can produce contaminants that can land on critical surfaces within the system. If contaminants accumulate on these surfaces, it can cause performance degradation and require invasive preventive maintenance that shuts down the machine. The vacuum chamber can be separated into different vacuum zones to prevent contaminants from reaching these surfaces.

[0006] Although sealing between different vacuum zones can be achieved between static components using typical elastomeric or metal knife edge seals, such seals are ineffective when the components must move relative to each other. The prior art relies on a narrow gap (or labyrinth seal) between two movable components to help limit cross contamination between zones. However, such seals only reduce the amount of material that can move between zones and do not result in a complete dynamic seal between the two components.

[0007] Therefore, a dynamic seal between two movable components in separate zones of the vacuum chamber is required. Summary of the invention

[0008] Embodiments of the present disclosure provide an apparatus comprising a vacuum chamber, a first component, a second component, and a gas ejector. The vacuum chamber may include a first vacuum region and a second vacuum region. The first component may be disposed at an interface with the second vacuum region in the first vacuum region. The second component may be disposed at the interface in the second vacuum region and spaced apart from the first component by a gap. The second component may move relative to the first component. The gas ejector may be configured to eject a buffer gas from at least one hole in at least one of the first component and the second component into the gap between the first component and the second component. The buffer gas may provide a dynamic seal between the first vacuum region and the second vacuum region during movement of the second component relative to the first component.

[0009] According to an embodiment of the present disclosure, the first vacuum region and the second vacuum region may be evacuated by separate vacuum pumps. At least one of the first vacuum region and the second vacuum region may be under ultra-high vacuum pressure.

[0010] According to an embodiment of the present disclosure, the at least one hole may include a plurality of holes, and the plurality of holes may be configured to guide the buffer gas toward the first vacuum region and the second vacuum region.

[0011] According to an embodiment of the present disclosure, the device may further include a seal. The seal may be disposed in the gap on the first component. The thickness of the seal may be smaller than the distance of the gap.

[0012] According to an embodiment of the present disclosure, the second component can move along the interface parallel to the first component.

[0013] According to an embodiment of the present disclosure, the first component may include a hole, and the second component covers the hole.

[0014] According to an embodiment of the present disclosure, the apparatus may further include an inspection tool. The inspection tool may be configured to inspect a sample disposed on the second component.

[0015] According to an embodiment of the present disclosure, the first component may be a shielding plate and the second component may be a stage.

[0016] Another embodiment of the present disclosure provides a method, which includes evacuating a first vacuum region and evacuating a second vacuum region. A first component may be disposed in the first vacuum region, and a second component may be disposed in the second vacuum region at an interface between the first vacuum region and the second vacuum region and spaced apart from the first component by a gap. The method may further include injecting a buffer gas from at least one hole in at least one of the first component and the second component into the gap between the first component and the second component. The buffer gas may provide a dynamic seal between the first component and the second component. The method may further include moving the second component relative to the first component while maintaining the dynamic seal.

[0017] According to an embodiment of the present disclosure, the at least one hole may include a plurality of holes, and ejecting the buffer gas from the at least one hole in at least one of the first component and the second component into the gap between the first component and the second component may include ejecting the buffer gas from the plurality of holes in at least one of the first component and the second component into the gap. The buffer gas may be guided from the plurality of holes to the first vacuum area and the second vacuum area.

[0018] According to an embodiment of the present disclosure, moving the second component relative to the first component may include moving the second component parallel to the first component along the interface.

[0019] According to an embodiment of the present disclosure, the method may further include inspecting the sample disposed on the second component using an inspection tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a more complete 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, wherein:

[0021] Figure 1 Describe the device according to the embodiment of the present disclosure;

[0022] Figure 2 is a bottom view of a first assembly according to an embodiment of the present disclosure;

[0023] Figure 3 is a top view of a second assembly according to an embodiment of the present disclosure;

[0024] Figure 4A is a cross-sectional side view of a gas injector according to an embodiment of the present disclosure;

[0025] Figure 4Bis a top view of a gas injector according to an embodiment of the present disclosure;

[0026] Figure 5A illustrate Figure 1 Alternative arrangements of equipment;

[0027] Figure 5B illustrate Figure 1 Another alternative arrangement of the equipment;

[0028] Figure 6 is a flow chart of a method according to an embodiment of the present disclosure; and

[0029] Figure 7 A system according to an embodiment of the present disclosure is described. DETAILED DESCRIPTION

[0030] Although the present disclosure will be described in terms of specific 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 electronic changes may be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure is defined solely by reference to the appended claims.

[0031] Embodiments of the present disclosure provide Figure 1 100. The apparatus 100 may include a vacuum chamber 105. The vacuum chamber 105 may include a first vacuum region 101 and a second vacuum region 102. The first vacuum region 101 and the second vacuum region 102 may be evacuated by separate vacuum pumps. For example, the first vacuum region 101 may be evacuated by a first vacuum pump 103, and the second vacuum region 102 may be evacuated by a second vacuum pump 104. The first vacuum pump 103 and the second vacuum pump 104 may control the vacuum chamber 105 to a low or vacuum pressure in the first vacuum region 101 and the second vacuum region 102. The vacuum pressure may be less than 10 -7 For example, the vacuum pressure may be an ultra-high vacuum (UHV) level (e.g., at 10 -7 mbar to 10 -12 The first vacuum region 101 and the second vacuum region 102 may maintain the same pressure or different pressures.

[0032] The apparatus 100 may further include a first component 110. The first component 110 may be disposed in the first vacuum region 101 at an interface with the second vacuum region 102. The first component 110 may have a first side 111 facing the interface with the second vacuum region 102 and a second side 112 opposite to the first side 111. The first component 110 may have a pore 113 extending from the first side 111 to the second side 112. The pore 113 may be centrally disposed in the first component 110. Figure 2 As shown in , the pores 113 can have a circular or polygonal shape.

[0033] The apparatus 100 may further include a second component 120. The second component 120 may be disposed in the second vacuum region 102 at an interface with the first vacuum region 101. The second component 120 may have a first side 121 facing the interface with the first vacuum region 101 and a second side 122 opposite to the first side 121. The second component 120 may be spaced apart from the first component 110 by a gap 123. The size of the gap 123 may depend on the size of the components of the apparatus 100 (e.g., the vacuum chamber 105, the first component 110, the second component 120, etc.) or the gas pressure applied to the gap 123 (i.e., a stronger gas pressure may require a larger gap to prevent excessive impact of the moving element due to the gas pressure). In some embodiments, the gap 123 may be as small as a few nanometers or a few hundred micrometers. For example, the gap 123 may be about 100 μm. The second component 120 may cover the aperture 113 of the first component 110. The second component 120 may move relative to the first component 110. For example, the second component 120 may move parallel to the first component 110 in at least one direction. The second component 120 can move in two orthogonal directions parallel to the first component 110. The second component 120 can be moved by an xy actuation system (not shown). When the second component 120 moves relative to the first component 110, the first component 110 and the second component 120 can maintain a gap 123 between them.

[0034] According to an embodiment of the present disclosure, the first component 110 may be a shielding plate or a vacuum chamber wall separating the first vacuum region 101 from the second vacuum region. The second component 120 may be a stage that can move within the vacuum chamber 105. For example, the second component 120 may include a platform 124. The platform 124 may extend through the aperture 113 of the first component 110 into the first vacuum region 101. The platform 124 may be configured to receive a sample 125. Therefore, the sample 125 may be disposed in the first vacuum region 101, and the actuating component configured to move the second component 120 may be disposed in the second vacuum region 102. The sample 125 may be a target or workpiece, such as a semiconductor wafer or a photomask. In this configuration, the aperture 113 in the first component 110 may allow the second component 120 to move within a specific range of motion. Due to the extremely small thickness of the gap 123, a limited amount of contaminants may travel between the first vacuum region 101 and the second vacuum region 102 via the gap 123 and the aperture 113. Although the apparatus 100 is described with respect to a shield plate and a stage, it should be understood that the first component 110 and the second component 120 may be other components that move relative to each other in a vacuum chamber.

[0035] The apparatus 100 may further include a gas injector 130. The gas injector 130 may be configured to inject a buffer gas 131 into the gap 123 between the first component 110 and the second component 120. The buffer gas 131 may be provided by a buffer gas source 132. The buffer gas 131 may be clean dry air (CDA), nitrogen, or an inert gas (e.g., argon). The buffer gas source 132 may be configured to control the flow rate of the buffer gas 131. When the buffer gas 131 is injected into the gap 123, the buffer gas 131 may travel to the first vacuum region 101 and / or the second vacuum region 102. Therefore, the buffer gas 131 may be removed from the vacuum chamber 105 by the first vacuum pump 103 and / or the second vacuum pump 104. The buffer gas source 132 may be configured to control the flow rate of the buffer gas 131 to minimize the pumping requirements of the first vacuum pump 103 and the second vacuum pump 104.

[0036] The gas injector 130 may inject the buffer gas 131 from at least one hole 135 in at least one of the first component 110 and the second component 120. For example, the at least one hole 135 may be disposed on the first side 111 of the first component 110 and / or the first side 121 of the second component 120. Figure 1 In the device 100 described in FIG. 1 , the at least one hole 135 is shown as being on the first side 121 of the second component 120, but it should be understood that the at least one hole 135 may alternatively be disposed on the first side 111 of the first component 110 (e.g., Figure 5A ) or disposed on both the first side 121 of the second component 120 and the first side 111 of the first component 110 (as shown in Figure 5B When the gas injectors 130 are disposed on both sides of the gap 123, separate buffer gas sources 132 may be provided to supply the buffer gas 131 from each side, or a single buffer gas source 132 may be provided (eg, Figure 5B ) to supply the buffer gas 131 to both sides. The gas injector 130 may include a single gas injector configured to inject the buffer gas 131 from one or more holes 135 or a plurality of gas injectors each configured to inject the buffer gas 131 from one or more holes 135. For example, Figure 3 , the plurality of gas injectors 130 may be arranged in a ring around the edge of the first side 121 of the second component 120. Alternatively, a ring-shaped gas injector having holes arranged in a similar manner may be provided. Although the plurality of gas injectors 130 are illustrated as being arranged in a circular manner, other arrangements are possible depending on the shape of the first component 110 and / or the second component 120. For example, for a square or rectangular first component 110 (or aperture 113) or second component 120, the plurality of gas injectors 130 may be arranged in a polygonal shape.

[0037] According to an embodiment of the present disclosure, each gas injector 130 may inject buffer gas 131 from a plurality of holes 135. For example, Figure 4B As shown in FIG. 1 , the gas injector 130 may inject the buffer gas 131 from a plurality of holes 135 in an array. The plurality of holes 135 may be configured to guide the buffer gas 131 toward the first vacuum region 101 and / or the second vacuum region 102. For example, Figure 4A , the plurality of holes may include straight holes 135a, inward holes 135b, and / or outward holes 135c. The straight holes 135a may be configured to vertically guide the buffer gas 131 from the first side 111 of the first component 110 and / or the first side 121 of the second component 120. Thus, the buffer gas 131 may be spread to both the first vacuum region 101 and the second vacuum region 102. The inward holes 135b may be configured to guide the buffer gas 131 at an acute angle from the first side 111 of the first component 110 and / or the first side 121 of the second component 120. Thus, the buffer gas 131 may be spread inward toward the first vacuum region 101. The outward holes 135c may be configured to guide the buffer gas 131 at an obtuse angle from the first side 111 of the first component 110 and / or the first side 121 of the second component 120. Thus, the buffer gas 131 may be spread outward toward the second vacuum region 102. It should be understood that the at least one aperture 135 may include all or some of these three types of apertures or may include only one type of aperture.

[0038] An air curtain may be generated by injecting a buffer gas 131 into the gap 123, which may provide a dynamic seal between the first vacuum region 101 and the second vacuum region 102. The dynamic seal may prevent contaminants from being transferred between the first vacuum region 101 and the second vacuum region 102 when the first component 110 and the second component 120 are fixed and during movement of the second component 120 relative to the first component 110.

[0039] The apparatus 100 may further include a seal 115 disposed in the gap 123 on the first component 110 or the second component 120. For example, Figure 1 As shown in FIG. 1 , the seal 115 may be disposed on the first side 111 of the first component 110 opposite the gas injector 130. Alternatively, when the gas injector 130 is disposed on the first side 111 of the first component 110 (eg, Figure 5A123), the seal 115 may be disposed on the first side 121 of the second component 120. It should be understood that when the gas injector 130 is disposed on both sides of the gap 123, the hole 135 may extend through or around the seal 115 on the first side 111 of the first component 110 and / or the seal 115 on the first side 121 of the second component 120. The seal 115 may also be integrally formed as part of the first component 110 or the second component 120. The seal 115 may be made of the same material as the first component 110 or the second component 120 or may be made of a different material. Figure 2 , the seal 115 may be annular and may surround the aperture 113 of the first component 110. The thickness of the seal 115 may be less than the distance of the gap 123. In other words, the seal 115 may not completely fill the distance between the first component 110 and the second component 120, so that the effective distance of the gap 123 between the first component 110 and the second component 120 may be narrowed. It should be understood that the buffer gas 131 may be disposed in the gap 123 together with the seal 115 to further prevent contaminants from being transferred between the first vacuum region 101 and the second vacuum region 102. Using the seal 115 to narrow the gap 123 may further reduce the amount of contaminants that may be transferred between the first vacuum region 101 and the second vacuum region 102, and may improve the effectiveness of the dynamic seal provided by the buffer gas 131. The width of the seal 115 may depend on the travel range of the second component 120. In other words, the seal 115 may be wide enough to span the gap 123 from the buffer gas injector 130 when the second assembly 120 moves relative to the first assembly 110 .

[0040] The apparatus 100 may further include an inspection tool 140. The inspection tool 140 may be disposed in the first vacuum region 101. The inspection tool 140 may be configured to inspect a sample 125 disposed on the second component 120. The inspection tool 140 may have an optical axis 145 directed toward the sample 125 to inspect portions of the sample 125 that intersect the optical axis 145. The inspection tool 140 may direct extreme ultraviolet (EUV) light, deep ultraviolet (DUV) light, broadband light, 266nm or 193nm lasers, x-ray beams, electron beams, or other types of beams along the optical axis 145 to inspect the sample 125. By moving the second component 120 relative to the first component 110, the sample 125 may also be moved so that different portions of the sample 125 may intersect the optical axis 145 for inspection.

[0041] Using the apparatus 100, a dynamic seal can be provided between the first component 110 and the second component 120, which can be maintained when the second component 120 moves relative to the first component 110. This dynamic seal can prevent contaminants from being transferred between the first vacuum region 101 and the second vacuum region 102 of the vacuum chamber 105 to prevent cross contamination and make it easier to maintain an ultra-clean vacuum system.

[0042] The embodiment of the present disclosure provides a method 200. Figure 6 As shown in , method 200 may include the following steps.

[0043] At step 210, a first vacuum region is evacuated. The first vacuum region may be part of a larger vacuum chamber. The first vacuum region may be evacuated to a low or vacuum pressure by a first vacuum pump. The vacuum pressure may be less than 10 -7 For example, the vacuum pressure may be an ultra-high vacuum (UHV) level (e.g., at 10 -7 mbar to 10 -12 mbar). The first component may be disposed in the first vacuum region.

[0044] At step 220, the second vacuum region is evacuated. The second vacuum region may be another portion of a larger vacuum chamber, separate from the first vacuum region. The second vacuum region may be evacuated to a low or vacuum pressure by a second vacuum pump. The pressure in the second vacuum region may be the same as or different from the first vacuum region. The second component may be disposed in the second vacuum region at an interface between the first vacuum region and the second vacuum region, such that a gap separates the first component and the second component.

[0045] Although steps 210 and 220 are described separately, it should be understood that steps 210 and 220 can be performed simultaneously or in overlapping succession. For example, the first vacuum pump and the second vacuum pump can be started simultaneously or sequentially so that each chamber reaches the desired pressure. Lower pressures can be achieved by operating two vacuum pumps simultaneously because gas will not leak from another chamber at atmospheric pressure to the evacuation chamber.

[0046] In step 230, a buffer gas is injected into the gap between the first component and the second component from at least one hole in at least one of the first component and the second component. The buffer gas can provide a dynamic seal between the first component and the second component. The buffer gas can be provided by a buffer gas source. The buffer gas can be clean dry air (CDA), nitrogen, or an inert gas (e.g., argon). The buffer gas source can be configured to control the flow rate of the buffer gas. When the buffer gas is injected into the gap, the buffer gas can travel to the first vacuum region and / or the second vacuum region. Therefore, the buffer gas can be removed from the vacuum chamber by the first vacuum pump and / or the second vacuum pump. The buffer gas source can be configured to control the flow rate of the buffer gas to minimize the pumping requirements of the first vacuum pump and the second vacuum pump. The buffer gas can be injected by a single gas injector or multiple gas injectors. Each buffer gas injector can be configured to inject buffer gas from one or more holes. For example, buffer gas can be injected from multiple holes in an array. Multiple holes can be configured to guide the buffer gas toward the first vacuum region and / or the second vacuum region. For example, the plurality of holes may include straight holes, inward holes, and outward holes. The straight holes may be configured to direct the buffer gas vertically from the first component and / or the second component so that the buffer gas is dispersed to both the first vacuum region and the second vacuum region. The inward holes may be configured to direct the buffer gas at an acute angle from the first component and / or the second component so that the buffer gas is dispersed inward toward the first vacuum region. The outward holes may be configured to direct the buffer gas at an obtuse angle from the first component and / or the second component so that the buffer gas is dispersed outward toward the second vacuum region. It should be understood that the at least one hole may include all or some of these three types of holes or may include only one type of hole.

[0047] At step 240, the second component is moved relative to the first component while maintaining a dynamic seal. The second component may be movable relative to the first component. For example, the second component may be movable parallel to the first component in at least one direction. The second component may be movable parallel to the first component in two orthogonal directions. The first component and the second component may remain spaced apart by a gap while the second component moves relative to the first component. An air curtain may be generated by injecting a buffer gas into the gap, which may provide a dynamic seal between the first component and the second component and their respective vacuum regions. The dynamic seal may prevent contaminants from being transferred between the first vacuum region and the second vacuum region when the first component and the second component are fixed and during movement of the second component relative to the first component.

[0048] At step 250, an inspection tool is used to inspect a sample disposed on the second component. The inspection tool may be disposed in the first vacuum region. The inspection tool may be configured to inspect a sample disposed on the second component. The inspection tool may have an optical axis directed toward the sample to inspect portions of the sample that intersect the optical axis. The inspection tool may direct extreme ultraviolet (EUV) light, deep ultraviolet (DUV) light, broadband light, 266nm or 193nm lasers, x-ray beams, electron beams, or other types of light / beams along the optical axis to inspect the sample. By moving the second component relative to the first component, the sample may also be moved so that different portions of the sample may intersect the optical axis for inspection.

[0049] Using the method, a dynamic seal can be provided between the first component and the second component, and the dynamic seal can be maintained when the second component moves relative to the first component. This dynamic seal can prevent contaminants from being transferred between the first vacuum area and the second vacuum area of ​​the vacuum chamber to prevent cross contamination and make it easier to maintain an ultra-clean vacuum system.

[0050] Figure 7 is a block diagram of an embodiment of a system 300 according to another embodiment of the present disclosure. The system 300 includes an optical-based subsystem 301. In general, the optical-based subsystem 301 is configured to generate an optical-based output of a sample 302 by directing light to (or scanning light across) the sample 302 and detecting light from the sample 302. In one embodiment, the sample 302 includes a wafer. The wafer may include any wafer known in the art. In another embodiment, the sample 302 includes a reticle. The reticle may include any reticle known in the art.

[0051] exist Figure 7 In the embodiment of the system 300 shown in FIG. 3 , the optical-based subsystem 301 includes an illumination subsystem configured to direct light to the sample 302. The illumination subsystem includes at least one light source. For example, Figure 7 , the illumination subsystem includes a light source 303. In one embodiment, the illumination subsystem is configured to direct light to the sample 302 at one or more incident angles (which may include one or more oblique angles and / or one or more normal angles). Figure 7 , light from light source 303 is directed through optical element 304 and then lens 305 to sample 302 at an oblique angle of incidence. The oblique angle of incidence may include any suitable oblique angle of incidence, which may vary depending on, for example, the characteristics of sample 302.

[0052] The optical-based subsystem 301 can be configured to direct light at different incident angles at different times to the sample 302. For example, the optical-based subsystem 301 can be configured to modify one or more characteristics of one or more elements of the illumination subsystem so that the light can be directed to the sample 302 at different angles of incidence. Figure 7302. In one such example, the optical-based subsystem 301 can be configured to move the light source 303, the optical element 304, and the lens 305 so that light is directed to the sample 302 at different oblique angles of incidence or normal (or near normal) angles of incidence.

[0053] In some examples, the optical-based subsystem 301 can be configured to simultaneously direct light at more than one incident angle to the sample 302. For example, the illumination subsystem can include more than one illumination channel, one of which can include, for example, Figure 7 303, optical element 304, and lens 305 are shown in FIG. 304, and another of the illumination channels (not shown) may include similar elements that may be configured differently or identically or may include at least a light source and possibly one or more other components, such as those described further herein. If this light is directed to the sample simultaneously with other light, one or more characteristics (e.g., wavelength, polarization, etc.) of the light directed to the sample 302 at different incident angles may be different, such that light resulting from illuminating the sample 302 at different incident angles may be distinguished from one another at a detector.

[0054] In another example, the illumination subsystem may include only one light source (eg, Figure 7 ) and the light from the light source may be separated into different optical paths (e.g., based on wavelength, polarization, etc.) by one or more optical elements (not shown) of the illumination subsystem. Then, the light in each of the different optical paths may be directed to the sample 302. Multiple illumination channels may be configured to direct light to the sample 302 simultaneously or at different times (e.g., when different illumination channels are used to sequentially illuminate the sample). In another example, the same illumination channel may be configured to direct light with different characteristics to the sample 302 at different times. For example, in some examples, the optical element 304 may be configured as a spectral filter and the properties of the spectral filter may be changed in a variety of different ways (e.g., by swapping out the spectral filter) so that different wavelengths of light may be directed to the sample 302 at different times. The illumination subsystem may have any other suitable configuration known in the art for directing light with different or the same characteristics to the sample 302 sequentially or simultaneously at different or the same angles of incidence.

[0055] In one embodiment, light source 303 may include a broadband plasma (BBP) source. In this way, the light generated by light source 303 and directed to sample 302 may include broadband light. However, the light source may include any other suitable light source, such as a laser. The laser may include any suitable laser known in the art and may be configured to generate light of any suitable wavelength known in the art. In addition, the laser may be configured to generate monochromatic or near-monochromatic light. In this way, the laser may be a narrow-band laser. Light source 303 may also include a polychromatic light source that generates light of multiple discrete wavelengths or bands.

[0056] Light from optical element 304 can be focused onto sample 302 by lens 305. Figure 7 305 is shown as a single refractive optical element, but it is understood that in reality, lens 305 may include several refractive and / or reflective optical elements that combine to focus light from the optical element onto the sample. Figure 7 The illumination subsystem shown in and described herein may include any other suitable optical elements (not shown). Examples of such optical elements include, but are not limited to, polarization components, spectral filters, spatial filters, reflective optical elements, apodizers, beam splitters (such as beam splitter 313), apertures, etc., which may include any such suitable optical elements known in the art. Additionally, the optical-based subsystem 301 may be configured to alter one or more elements of the illumination subsystem based on the type of illumination used to produce the optical-based output.

[0057] The optical-based subsystem 301 may also include a scanning subsystem configured to scan light across the sample 302. For example, the optical-based subsystem 301 may include a stage 306 on which the sample 302 is disposed during the generation of the optical-based output. The scanning subsystem may include any suitable mechanical and / or robotic assembly (including the stage 306) that may be configured to move the sample 302 such that light may be scanned across the sample 302. Additionally or alternatively, the optical-based subsystem 301 may be configured such that one or more optical elements of the optical-based subsystem 301 perform a certain scan of light across the sample 302. The light may be scanned across the sample 302 in any suitable manner, such as along a serpentine path or along a spiral path. The stage 306 may correspond to a portion of the second component 120 of the apparatus 100 described above.

[0058] The optical-based subsystem 301 further includes one or more detection channels. At least one of the one or more detection channels includes a detector configured to detect light from the sample 302 due to illumination of the sample 302 by the subsystem and to generate an output in response to the detected light. For example, Figure 7 The optical-based subsystem 301 shown in FIG. 1 includes two detection channels, one formed by a light collector 307, an element 308, and a detector 309, and the other formed by a light collector 310, an element 311, and a detector 312. Figure 7 , the two detection channels are configured to collect and detect light at different collection angles. In some examples, the two detection channels are configured to detect scattered light, and the detection channels are configured to detect light scattered at different angles from the sample 302. However, one or more of the detection channels may be configured to detect another type of light from the sample 302, such as reflected light.

[0059] like Figure 7 As further shown in , the two detection channels are shown as being positioned in the plane of the paper and the illumination subsystem is also shown as being positioned in the plane of the paper. Thus, in this embodiment, the two detection channels are positioned (e.g., centered) within the plane of incidence. However, one or more of the detection channels may be positioned outside the plane of incidence. For example, the detection channel formed by the light collector 310, the element 311, and the detector 312 may be configured to collect and detect light scattered out of the plane of incidence. Thus, this detection channel may be generally referred to as a "side" channel, and this side channel may be centered in a plane that is substantially perpendicular to the plane of incidence.

[0060] although Figure 7 An embodiment of an optical-based subsystem 301 including two detection channels is shown, but the optical-based subsystem 301 may include a different number of detection channels (e.g., only one detection channel or two or more detection channels). In one such example, the detection channel formed by the light collector 310, the element 311, and the detector 312 may form one side channel as described above, and the optical-based subsystem 301 may include an additional detection channel (not shown) formed as another side channel positioned on the opposite side of the incident plane. Thus, the optical-based subsystem 301 may include a detection channel that includes the light collector 307, the element 308, and the detector 309 and is centered in the incident plane and is configured to collect and detect light at a scattering angle normal to or close to normal to the surface of the sample 302. Thus, this detection channel may be generally referred to as a "top" channel, and the optical-based subsystem 301 may also include two or more side channels configured as described above. Thus, the optical-based subsystem 301 may include at least three channels (i.e., one top channel and two side channels), and each of the at least three channels has its own collector, each of which is configured to collect light at a different scattering angle than each of the other collectors.

[0061] As further described above, each of the detection channels included in the optical-based subsystem 301 can be configured to detect scattered light. Figure 7 The optical-based subsystem 301 shown in FIG. 301 may be configured for dark field (DF) output generation of the sample 302. However, the optical-based subsystem 301 may also or alternatively include a detection channel configured for bright field (BF) output generation of the sample 302. In other words, the optical-based subsystem 301 may include at least one detection channel configured to detect light specularly reflected from the sample 302. Thus, the optical-based subsystem 301 described herein may be configured for DF-only, BF-only, or both DF and BF imaging. Although each of the light collectors is Figure 71 and 2. Although shown as a single refractive optical element in FIG. 2 , it should be understood that each of the light collectors may include one or more refractive optical dies and / or one or more reflective optical elements.

[0062] One or more detection channels may include any suitable detector known in the art. For example, the detector may include a photomultiplier tube (PMT), a charge coupled device (CCD), a time delay integration (TDI) camera, and any other suitable detector known in the art. The detector may also include a non-imaging detector or an imaging detector. In this way, if the detector is a non-imaging detector, each of the detectors may be configured to detect a specific characteristic (e.g., intensity) of the scattered light, but may not be configured to detect such characteristics that vary depending on the position within the imaging plane. Thus, the output generated by each of the detectors included in each of the detection channels of the optical-based subsystem may be a signal or data, but not an image signal or image data. In such examples, a processor (e.g., processor 314) may be configured to generate an image of the sample 302 from the non-imaging output of the detector. However, in other examples, the detector may be configured as an imaging detector configured to generate an imaging signal or image data. Thus, the optical-based subsystem may be configured to generate an optical image or other optical-based output described herein in a number of ways.

[0063] It should be noted that this article provides Figure 7 1 and 2 to generally illustrate configurations of optical-based subsystems 301 that may be included in or that may produce optical-based outputs used by system embodiments described herein. The configurations of the optical-based subsystems 301 described herein may be altered to optimize the performance of the optical-based subsystems 301 as is typically performed when designing commercial output capture systems. Additionally, the systems described herein may be implemented using existing systems (e.g., by adding the functionality described herein to the 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.

[0064] Processor 314 may be coupled to 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 314 may receive output. Processor 314 may be configured to use the output to perform a number of functions. System 300 may receive instructions or other information from processor 314. Processor 314 and / or electronic data storage unit 315 may optionally be in electronic communication with a wafer inspection tool, wafer metrology tool, or wafer recheck tool (not illustrated) to receive additional information or send instructions. For example, processor 314 and / or electronic data storage unit 315 may be in electronic communication with a scanning electron microscope.

[0065] The processor 314, other systems, or other subsystems described herein may be part of a variety of systems including personal computer systems, image computers, mainframe computer systems, workstations, network appliances, Internet appliances, or other devices. The subsystem or system may also include any suitable processor known in the art, such as a parallel processor. In addition, the subsystem or system may include a platform with high-speed processing and software as a stand-alone or networked tool.

[0066] Processor 314 and electronic data storage unit 315 may be disposed in or otherwise be part of system 300 or another device. In an example, processor 314 and electronic data storage unit 315 may be part of an independent control unit or in a centralized mass control unit. Multiple processors 314 or electronic data storage units 315 may be used.

[0067] Processor 314 may be implemented in practice by any combination of hardware, software, and firmware. Furthermore, its functions described herein may be performed by one unit or distributed among different components, each of which may be implemented by any combination of hardware, software, and firmware. Program code or instructions for processor 314 to implement various methods and functions may be stored in a readable storage medium, such as a memory in electronic data storage unit 315 or other memory.

[0068] If the system 300 includes more than one processor 314, different subsystems may be coupled to each other so that images, data, information, instructions, etc. may be sent between subsystems. For example, one subsystem may be coupled to an additional subsystem via any suitable transmission media (which may include any suitable wired and / or wireless transmission media known in the art). Two or more of such subsystems may also be operatively coupled by a shared computer-readable storage media (not shown).

[0069] The processor 314 may be configured to use the output of the system 300 or other output to perform a number of functions. For example, the processor 314 may be configured to send the output to an electronic data storage unit 315 or another storage medium. The processor 314 may be configured according to any of the embodiments described herein. The processor 314 may also be configured to use the output of the system 300 or use images or data from other sources to perform other functions or additional steps.

[0070] The processor 314 may be configured to control one or more functions of the apparatus 100 and / or steps of the method 200 described above. For example, the processor 314 may be configured to control the second component 120 of the apparatus 100 to move relative to the first component 110. The processor 314 may be configured to control the buffer gas injector 130 to inject the buffer gas 131 into the gap 123 between the first component 110 and the second component 120 of the apparatus 100. The processor 314 may be configured to control the first vacuum pump 103 and / or the second vacuum pump 104 to evacuate the first vacuum region 101 and / or the second vacuum region 102 to a low or vacuum pressure.

[0071] The various steps, functions and / or operations of the system 300 and methods disclosed herein are performed by one or more of: electronic circuits, logic gates, multiplexers, programmable logic devices, ASICs, analog or digital controls / switches, microcontrollers, or computing systems. Program instructions implementing methods (such as the methods described herein) may be transmitted through or stored on a carrier medium. The carrier medium may include storage media, such as read-only memory, random access memory, magnetic or optical disks, non-volatile memory, solid-state memory, magnetic tape, etc. The carrier medium may include transmission media, such as wires, cables, or wireless transmission links. For example, the various steps described throughout the present disclosure may be performed by a single processor 314 or, alternatively, multiple processors 314. In addition, different subsystems of the system 300 may include one or more computing or logic systems. Therefore, the above description should not be construed as limiting the present disclosure, but is merely illustrative.

[0072] Although the present disclosure has been described with respect to one or more specific embodiments, it should be understood that other embodiments of the present disclosure can be made without departing from the scope of the present disclosure. Therefore, the present disclosure should be deemed to be limited only by the appended claims and reasonable interpretation thereof.

Claims

1. A device comprising: A vacuum chamber comprising a first vacuum region and a second vacuum region; A first component disposed in the first vacuum region at an interface with the second vacuum region; a second component disposed at the interface in the second vacuum region and spaced apart from the first component by a gap, wherein the second component is movable relative to the first component; and a gas injector configured to inject a buffer gas from at least one hole in at least one of the first component and the second component into the gap between the first component and the second component; The buffer gas provides a dynamic seal between the first vacuum region and the second vacuum region during movement of the second component relative to the first component.

2. The apparatus according to claim 1, wherein the first vacuum region and the second vacuum region are evacuated by separate vacuum pumps.

3. The apparatus of claim 1, wherein at least one of the first vacuum region and the second vacuum region is at an ultra-high vacuum pressure. The apparatus of claim 1 , wherein the at least one hole comprises a plurality of holes.

5. The apparatus of claim 4, wherein the plurality of holes are configured to direct the buffer gas toward the first vacuum region and the second vacuum region.

6. The apparatus of claim 1, further comprising a seal disposed on the first component in the gap, wherein a thickness of the seal is less than a distance of the gap.

7. The apparatus of claim 1, wherein the second component is movable along the interface parallel to the first component.

8. The apparatus of claim 1, wherein the first component includes an aperture and the second component covers the aperture.

9. The apparatus of claim 1, further comprising an inspection tool configured to inspect a sample disposed on the second component.

10. The apparatus of claim 1, wherein the first component is a shielding plate and the second component is a stage.

11. A method comprising: evacuating a first vacuum region in which a first component is disposed; evacuating the second vacuum region, wherein the second component is disposed at an interface between the first vacuum region and the second vacuum region in the second vacuum region and is spaced apart from the first component by a gap; injecting a buffer gas from at least one hole in at least one of the first component and the second component into the gap between the first component and the second component, wherein the buffer gas provides a dynamic seal between the first component and the second component; and The second component is moved relative to the first component while maintaining the dynamic seal. 12 . The method of claim 11 , wherein the first vacuum zone and the second vacuum zone are evacuated by separate vacuum pumps.

13. The method of claim 11, wherein at least one of the first vacuum region and the second vacuum region is at an ultra-high vacuum pressure.

14. The method of claim 11, wherein the at least one hole comprises a plurality of holes, and injecting the buffer gas from the at least one hole in at least one of the first component and the second component into the gap between the first component and the second component comprises: The buffer gas is injected into the gap from the plurality of holes in at least one of the first component and the second component. 15 . The method of claim 14 , wherein the buffer gas is guided to the first vacuum region and the second vacuum region through the plurality of holes.

16. The method of claim 11, wherein a seal is disposed on the first component in the gap, and a thickness of the seal is less than a distance of the gap.

17. The method of claim 11, wherein moving the second component relative to the first component comprises: The second component is moved along the interface parallel to the first component.

18. The method of claim 11, wherein the first component includes an aperture and the second component covers the aperture.

19. The method of claim 11, further comprising: The sample disposed on the second component is inspected using an inspection tool.

20. The method of claim 11, wherein the first component is a shielding plate and the second component is a stage.

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