Hybrid vacuum electrostatic chuck in special chamber for high-warpage wafer

Abstract

A method of processing a substrate in a processing chamber including a main region and an auxiliary region environmentally isolatable from the main region, the method including transferring the substrate to the main region of the processing chamber and placing the substrate on an upper surface of a substrate holder while the main region is at a vacuum pressure, wherein the substrate holder includes one or more vacuum channels disposed on the upper surface and one or more electrodes disposed in the substrate holder proximate the upper surface; moving the substrate holder within the processing chamber to move the substrate from the primary region to the secondary region; sealing the auxiliary area from the main area and increasing the pressure in the auxiliary area; adsorbing and flattening the substrate to the substrate holder by applying a vacuum to the one or more vacuum channels when the substrate is located within the auxiliary region; applying a voltage to the one or more electrodes to further absorb the substrate to the substrate holder using an electrostatic force when the substrate is located in the auxiliary area and absorbed to the substrate holder through the one or more vacuum channels; while the substrate is adsorbed to the substrate holder by the electrostatic force, the substrate is moved from the auxiliary region back to the main region and processed at the main region with a vacuum pressure.

Description

TECHNICAL FIELD

[0001] This application claims the benefit of and priority to U.S. Patent Application No. 18 / 749,495, filed June 20, 2024, entitled “Hybrid Vacuum Electrostatic Chuck in Highly Warped Wafer Dedicated Chamber,” which is hereby incorporated by reference in its entirety.

[0002] Commonly-assigned U.S. Patent Application No. 18 / 749,474, filed June 20, 2024, entitled “Hybrid Vacuum Electrostatic Chuck Carrier for Highly Warped Wafers,” which is hereby incorporated by reference in its entirety.

[0003] Commonly-assigned U.S. Patent Application No. 18 / 749,484, filed June 20, 2024, entitled “Hybrid Vacuum Electrostatic Chuck in Vacuum Chamber for Highly Warped Wafers,” which is hereby incorporated by reference in its entirety. BACKGROUND

[0004] In the study of electronic materials and the processes by which these materials are fabricated into electronic structures, samples, such as semiconductor wafers, can be analyzed in a scanning electron microscope (SEM) to study particular features in the wafer. Such features can include fabricated circuitry and any defects that formed during the fabrication process. Electron microscopes are among the most useful devices for analyzing the microscopic structure of semiconductor components.

[0005] In such inspection processes, multiple locations on a sample are typically inspected. In doing so, the sample must be completely flat to ensure that the measurements or other analyses performed are accurate. While many samples, such as semiconductor substrates or “wafers,” can appear flat at initial observation, these samples can have a relatively high degree of warpage.

[0006] In the semiconductor industry, a variety of different types of sample support structures are commonly used to secure and flatten wafers during processing. One such support structure is an electrostatic chuck, which includes one or more electrodes positioned beneath a surface that supports the sample. If the sample is electrically conductive, a voltage can be applied to the electrodes to attract and flatten the sample to the chuck. Electrostatic chucks are very effective at flattening wafers that are only slightly or moderately warped, but can be ineffective or unable to flatten highly warped wafers.

[0007] Another support structure is a vacuum chuck, which attracts and flattens a sample to the chuck by applying a vacuum to the backside of the sample. Vacuum chucks are very effective at securing and flattening wafers, including highly warped wafers that cannot be flattened by electrostatic chucks, but cannot be used to secure or flatten wafers in sample processing chambers that process substrates with vacuum pressure.

[0008] While many variations of electrostatic and vacuum chucks have been designed over the years, some previously designed chucks have limited ability to support and completely flatten highly warped wafers held under vacuum pressure during substrate processing operations as described above. Therefore, new and improved systems are desirable for flattening warped samples and supporting them in substrate processing tools. Summary of the Invention

[0009] The embodiments described herein provide a method and system for supporting, flattening, and then processing samples, including highly warped substrates or wafers. While the embodiments of this disclosure can be used to support and flatten many different types of samples that may be warped to varying degrees before being processed in a vacuum chamber, certain embodiments are particularly well-suited for supporting and flattening large, thin wafers, such as semiconductor wafers, which may be highly warped and therefore cannot be flattened by certain conventional electrostatic chucks.

[0010] As described herein, for certain processing operations performed on a sample, the sample must be completely flattened. For example, when imaging different locations on a wafer using a scanning electron microscope (SEM), the working distance between the column tip and the sample must be precisely known. Therefore, for this purpose, the methods and systems described herein flatten the sample before performing processing operations (e.g., SEM imaging operations) on it. In some embodiments, the sample is flattened in a load lock or similar chamber before being transferred to a substrate processing chamber. In other embodiments, the sample is transferred to a main processing chamber and then flattened within the main processing chamber before substrate processing operations are performed. In other embodiments, the processing chamber includes a main chamber region where the sample is processed, and a separate, smaller chamber region isolated from the main chamber (sometimes referred to herein as an “auxiliary region”). The sample may be moved to the auxiliary region and preliminarily flattened before being moved back to the main processing region before performing substrate processing operations. Details of these embodiments are described below.

[0011] While some embodiments of the methods and systems disclosed herein are particularly useful for flattening warped wafers prior to performing imaging operations within the vacuum chamber of SEM tools, these embodiments are not limited to any particular type of substrate handling operation or substrate handling tool. The embodiments described herein can be used for pre-processing fixation and flattening of samples in other types of sample handling tools that process samples in high, very high, or ultra-high vacuum environments.

[0012] According to some embodiments, a method for processing a substrate in a processing chamber comprising a main region and an auxiliary region is disclosed, wherein the auxiliary region may be isolated from the main region environment. The method may include: transferring the substrate to the main region of the processing chamber and placing it on the upper surface of a substrate holder while the main region is under vacuum pressure, wherein the substrate holder includes one or more vacuum channels disposed on the upper surface and one or more electrodes disposed in the substrate holder near the upper surface; moving the substrate holder within the processing chamber to move the substrate from the main region to the auxiliary region; sealing the auxiliary region to the main region and increasing the pressure within the auxiliary region; while the substrate is located within the auxiliary region, adsorbing and flattening the substrate to the substrate holder by applying a vacuum to one or more vacuum channels; while the substrate is located within the auxiliary region and adsorbed to the substrate holder through one or more vacuum channels, applying a voltage to one or more electrodes to further adsorb the substrate to the substrate holder using electrostatic force; and while the substrate is adsorbed to the substrate holder by electrostatic force, moving the substrate back from the auxiliary region to the main region and processing the substrate under vacuum pressure in the main region.

[0013] In various embodiments, these embodiments may include one or more of the following: An auxiliary region may be directly connected to the cover of the substrate processing chamber. Increasing the pressure within the auxiliary region may include venting the auxiliary region to the atmosphere. After electrostatically adsorbing the substrate to a substrate holder within the auxiliary region, and before transferring the substrate from the auxiliary region back to the main region, the auxiliary region is evacuated to a vacuum pressure while continuing to electrostatically adsorb the substrate to the substrate holder. After processing the substrate under vacuum conditions in the main region, the applied voltage is stopped, causing the substrate to no longer be electrostatically adsorbed to the substrate holder, and the substrate is transferred out of the processing chamber. The processing chamber may include a scanning electron microscope, and processing the substrate in the processing chamber may include imaging the substrate using a scanning electron microscope. The warpage of the substrate may be at least 1.0 mm between the lowest and highest points on the substrate. The vacuum pressure for processing the substrate in the processing chamber may be a high vacuum pressure or lower. The one or more electrodes may include at least two electrodes arranged in an interleaved pattern. The substrate may be a semiconductor wafer.

[0014] In some embodiments, a system for processing a substrate is provided, comprising: a substrate processing chamber having a main processing region and an auxiliary region that can be isolated from the main processing region environment; a substrate support disposed within the substrate processing chamber and including one or more vacuum channels disposed on an upper surface and one or more electrodes disposed in the substrate support near the upper surface; a stage operatively coupled for moving the substrate support within the substrate processing chamber and moving between the main processing region and the auxiliary region; a transfer unit configured to transfer the substrate in and out of the substrate processing chamber; and a processor and memory coupled to a processor. The memory may include multiple computer-readable instructions that, when executed by a processor, cause the system to perform the following operations: While the main processing region is under vacuum pressure, transfer the substrate to the main processing region of the substrate processing chamber and place it on the upper surface of a substrate holder, wherein the substrate holder includes one or more vacuum channels disposed on the upper surface and one or more electrodes disposed in the substrate holder near the upper surface; move the substrate holder within the substrate processing chamber, moving the substrate from the main processing region to an auxiliary region; seal the auxiliary region to the main processing region and vent the auxiliary region to the atmosphere; while the substrate is located within the auxiliary region, adsorb and flatten the substrate to the substrate holder by applying a vacuum to one or more vacuum channels; while the substrate is located in the auxiliary region and adsorbed to the substrate holder through one or more vacuum channels, apply a voltage to one or more electrodes to further adsorb the substrate to the substrate holder using electrostatic force; while continuing to adsorb the substrate to the substrate holder using electrostatic force, evacuate the auxiliary region to vacuum pressure; while the main processing region is under vacuum pressure, move the substrate from the auxiliary region back to the main processing region, and simultaneously move the substrate holder; while the substrate is adsorbed to the substrate holder by electrostatic force, process the substrate in the main processing region under vacuum pressure.

[0015] In other additional implementations, a non-transitory computer-readable memory is provided. The computer-readable memory can store instructions for processing a substrate, including: transferring the substrate to the main processing area of ​​a processing chamber and placing it on the upper surface of a substrate holder while the main processing area is under vacuum pressure, wherein the substrate holder includes one or more vacuum channels disposed on the upper surface and one or more electrodes disposed in the substrate holder near the upper surface; moving the substrate holder within the processing chamber to move the substrate from the main processing area to an auxiliary area; sealing the auxiliary area to the main processing area and venting the auxiliary area to the atmosphere; when the substrate is located in the auxiliary area, adsorbing and flattening the substrate to the substrate holder by applying a vacuum to one or more vacuum channels; when the substrate is located in the auxiliary area and adsorbed to the substrate holder through one or more vacuum channels, applying a voltage to one or more electrodes to further adsorb the substrate to the substrate holder using electrostatic force; while continuing to adsorb the substrate to the substrate holder using electrostatic force, evacuating the auxiliary area to vacuum pressure; when the main processing area is under vacuum pressure, moving the substrate from the auxiliary area back to the main processing area and simultaneously moving the substrate holder; and processing the substrate in the main processing area under vacuum pressure while the substrate is adsorbed to the substrate holder by electrostatic force.

[0016] To better understand the nature and advantages of this disclosure, reference should be made to the following description and accompanying drawings. However, it should be understood that each drawing is for illustrative purposes only and is not intended to define a limitation on the scope of this disclosure. Furthermore, as a general principle, unless expressly stated otherwise in the description, elements using the same reference numerals in different drawings are generally identical or at least similar in function or purpose. Attached Figure Description

[0017] Figure 1 This is a simplified schematic diagram of a sample evaluation system that includes a scanning electron microscope (SEM) column;

[0018] Figures 2A-2C This is a simplified block diagram of a sample evaluation system that includes a substrate processing pillar and a load-locking chamber;

[0019] Figure 3A and 3B This is a simplified cross-sectional view of a previously known electrostatic chuck, showing the lifting rod in the rising and falling positions.

[0020] Figure 4A yes Figure 3A and 3B The image shows a simplified cross-section of an electrostatic chuck supporting a highly warped sample.

[0021] Figure 4B yes Figure 4A An enlarged view of the electrostatic chuck and sample portion shown in the image;

[0022] Figure 5AThis is a simplified cross-sectional view of a hybrid vacuum-electrostatic chuck carrier according to certain embodiments;

[0023] Figure 5B yes Figure 5A An enlarged view of the hybrid vacuum-electrostatic chuck carrier portion shown in the image;

[0024] Figure 6 This is a flowchart showing the steps of a method for flattening and processing a warped substrate according to certain embodiments;

[0025] Figures 7A-7I This is a simplified cross-sectional view of a substrate processing system according to certain embodiments, showing the process according to... Figure 6 Flattening and processing of warped substrates in different stages of the method described herein;

[0026] Figure 8A This is a simplified cross-sectional view of a hybrid vacuum-electrostatic chuck according to certain embodiments;

[0027] Figure 8B yes Figure 8A An enlarged view of the hybrid vacuum-electrostatic chuck section shown in the image;

[0028] Figure 9 This is a flowchart showing the steps of a method for flattening and processing a warped substrate according to certain embodiments;

[0029] Figures 10A-10D This is a simplified cross-sectional view of a substrate processing system according to certain embodiments, showing the process according to... Figure 9 Flattening and processing of warped substrates in different stages of the method described herein;

[0030] Figure 11 This is a flowchart illustrating the steps of a method for flattening and processing a warped substrate according to certain embodiments; and

[0031] Figures 12A-12G This is a simplified cross-sectional view of a substrate processing system according to certain embodiments, showing the system based on... Figure 11 The method proposed in the paper addresses the flattening and warped substrate treatment at different stages. Detailed Implementation

[0032] The embodiments described herein provide a method and system for supporting, flattening, and then processing samples, including highly warped substrates or wafers. While the embodiments of this disclosure can be used to support and flatten many different types of samples that may be warped to varying degrees before being processed in a vacuum chamber, certain embodiments are particularly well-suited for supporting and flattening large, thin wafers, such as semiconductor wafers, which may be highly warped and therefore cannot be flattened by certain conventional electrostatic chucks.

[0033] As described above, for certain processing operations performed on samples (e.g., semiconductor wafers), the samples must be completely flattened. The embodiments described herein provide a method and system for supporting, flattening, and then processing samples, including highly warped substrates or wafers before performing processing operations on the sample (e.g., before performing SEM imaging operations on different regions of interest on the sample within a vacuum chamber). In some embodiments, the sample is flattened in a load lock or similar chamber before being transferred to a substrate processing chamber. In other embodiments, the sample is transferred to a main processing chamber, where it is then flattened before the substrate processing operation. In still other embodiments, the processing chamber includes a main chamber region where the sample is processed, and a separate, smaller chamber region isolated from the main chamber (sometimes referred to herein as an "auxiliary region"). The sample may be moved to the auxiliary region and preliminarily flattened before being moved back to the main processing region before performing the substrate processing operation. Details of these embodiments are described below.

[0034] While the embodiments of this disclosure can be used to support and flatten many different types of samples that may be warped to varying degrees before being processed in a vacuum chamber, certain embodiments are particularly well-suited for supporting and flattening large, thin wafers, such as semiconductor wafers, which may be highly warped and therefore cannot be flattened by certain conventional electrostatic chucks. Furthermore, although some embodiments of the methods and systems disclosed herein are particularly useful before imaging operations on warped semiconductor or dielectric wafers, the embodiments are not limited to any particular type of substrate processing operation or substrate processing tool. The embodiments described herein can be used to process wafers (or samples) in sample processing tools that handle other types of samples, for fixing and flattening large wafers (and other types of samples) that require high, very high, or ultra-high vacuum environments during processing operations.

[0035] Example Sample Evaluation Tool

[0036] To better understand and appreciate this disclosure, please first refer to [reference needed]. Figure 1 This is a simplified schematic diagram of a previously known sample evaluation system 100. The sample evaluation system 100 can be used for operations including defect inspection and analysis of structures formed on samples, such as semiconductor or dielectric wafers.

[0037] System 100 may include a vacuum chamber 110 and a scanning electron microscope (SEM) column 120. Support element 140 may support a sample 150 (e.g., a semiconductor wafer) within chamber 110 during processing operations, wherein the sample 150 (sometimes referred to herein as an “object” or “specimen”) is irradiated by a beam of charged particles 126 from the SEM column.

[0038] SEM column 120 is connected to vacuum chamber 110, allowing the charged particle beam generated by the column to propagate through the vacuum environment created within vacuum chamber 110 before colliding with sample 150. SEM column 120 can generate an image of a portion of sample 150 by irradiating the sample with charged particle beam 125, detecting particles emitted due to irradiation, and generating a charged particle image based on the detected particles. For this purpose, SEM column 120 may include an electron beam source 122 (i.e., an "electron gun"), an anode tube 126 defining the electron beam drift space, a set of condenser lenses 124, one or more deflection lenses, such as lenses 130, 132, one or more focusing lenses 134, and a column cap 136.

[0039] During the imaging process, the electron beam 125 generated by the electron beam source 122 is initially focused by the condenser lens 124, and then further focused by the lens 134 before striking the sample 150. The condenser lens 124 defines the numerical aperture and current (along with the final aperture) of the electron beam, which is directly related to the resolution, while the focusing lens 134 focuses the beam onto the sample. The cap 136, located between the lower end of the anode tube 126 (first electrode) and the sample 150 (second electrode), can be the third electrode in the system, used to adjust the electric field generated around the wafer.

[0040] Figure 1 The diagram depicts the charged particle beam 125 generated by the SEM column 120 being approximately orthogonal to the sample 150 when the charged particle beam 125 collides with the sample 150. In various embodiments, the SEM column 120 may operate in an inclined mode, in which the charged particle beam 125 collides with the sample 150 at a non-perpendicular angle (e.g., 45 degrees).

[0041] In both conventional and tilt modes, particle imaging processes typically involve scanning a beam of charged particles back and forth within a specific region of the sample being imaged (e.g., using a grating or other scanning pattern). Deflecting lenses 130, 132 can be magnetic lenses, electrostatic lenses, or a combination of both, capable of achieving scanning patterns known to those skilled in the art. The scanned area is typically a very small fraction of the total area of ​​the sample. For example, the sample can be a semiconductor wafer with a diameter of 200 or 300 millimeters, and each scanned area on the wafer can be a rectangular region with a width and / or length measured in micrometers or tens of micrometers.

[0042] SEM column 120 may also include one or more detectors to detect charged particles generated from the sample during the imaging process. For example, SEM column 120 may include an in-lens detector 128 and a top detector 138, which may be configured to detect secondary electrons and backscattered electrons emitted by the charged particle beam 126 illuminating the sample. In-lens detector 128 may include a central aperture allowing the charged particle beam 126 to pass through the detector, while allowing secondary electrons and backscattered electrons entering the charged particle column 120 to pass through detector 128 and into top detector 138. In some embodiments, sample evaluation system 120 may also include an external detector, which may also be configured to detect secondary electrons and backscattered electrons, or may be configured to detect X-rays, such as an X-ray spectroscopy (EDX) detector.

[0043] During operation of system 100, support element 140 can move the sample so that different portions (e.g., different regions of interest or "ROIs") are directly within the field of view of SEM column 120. Support element 140 can move sample 150 relatively quickly within chamber 110, moving left and right, forward and backward (i.e., along the X and Y axes), and can also move sample 150 up and down, thereby moving the sample along the Z axis.

[0044] Because many feature sizes formed on sample 150 are on the micrometer scale or smaller, accurately knowing the focal position of the sample relative to SEM column 120 is crucial. To accurately determine the position of sample 150, a high-precision navigation interferometry system (not shown) can be used in some embodiments. This interferometry system can be mounted on the cover 112 of chamber 110 and guide collimated light (e.g., a laser beam) to a target area on support element 140, encoded with various linear or other markings, through a window (not shown) formed on the cover. The system can detect light from the collimated light pulses (e.g., using a photodetector array), which is reflected back from the encoded target area of ​​support element 140 before being reflected back to the interferometry system. A processor within the interferometry system (e.g., a digital signal processor) can then analyze the detected light signals to determine the sample's highly accurate position on the X and Y axes.

[0045] Furthermore, system 100 may include a voltage supply source 160 and one or more controllers 170, such as processors or other hardware units. The voltage supply source 160 may operate to provide a desired effective voltage to improve image resolution. This can be achieved by distributing an appropriate voltage supply between the first and second electrodes (i.e., between the anode tube and the sample). The controllers 170 may control the operation of the system, including the voltage supply source, by executing computer instructions stored in one or more computer-readable memories 180, as is known to those skilled in the art. For example, computer-readable memory may include solid-state memory (such as random access memory (RAM) and / or read-only memory (ROM), which may be programmable, flash-updatable, and / or similar), disk drives, optical disc storage devices, or similar non-transitory computer-readable storage media.

[0046] System 100 may further include a user interface 190 that allows one or more users to interact with the system. For example, user interface 190 may allow a user to set parameters of an SEM column or detector that can be used when analyzing samples. User interface 190 may include any known device that enables a user to input information to interact with the computer system, such as a keyboard, mouse, monitor, touchscreen, touchpad, voice-activated input controller, etc.

[0047] Transferring a sample to a processing chamber 110

[0048] To process sample 150 within chamber 110, the sample must first be transferred into that chamber. Although not shown in the accompanying drawings, some substrate processing systems include a fab interface that allows wafer cassettes to be processed to be loaded into a docking station. The docking station may include one or more front-opening pods (FOUPs), an industry standard for temporarily storing wafers for processing. A first external transfer unit (ETU), located in the processing system and operating between the docking station and the load-locked chamber, can pick up individual wafers from the FOUPs and transfer them to the load-locked chamber. The docking station and FOUPs are typically at atmospheric pressure.

[0049] The processing chamber 110 operates at a high vacuum, very high vacuum, or even ultra-high vacuum. The load-lock chamber typically has a smaller volume than the processing chamber and can be rapidly evacuated between atmospheric pressure and high vacuum levels as needed. For example, a wafer can be transferred into the load-lock chamber at atmospheric pressure. The load-lock chamber can then be evacuated, and a second internal transfer unit (ITU), located in the processing system and operating between the load-lock chamber and the processing chamber, can pick up the wafer from the load-lock chamber and transfer it to the processing chamber without interrupting the vacuum (i.e., while the load-lock chamber and the processing chamber are maintained at vacuum pressure). The first and second transfer units can be, for example, robotic arms with specially designed end actuators for transferring semiconductor wafers or similar samples from one location to another within a processing tool or station.

[0050] Once inside the processing chamber, the sample can be processed and then transferred back to the load-locked chamber without breaking the vacuum. The load-locked chamber can then be vented to the atmosphere, and the ITU can retrieve the processed sample for transfer to later stages of the manufacturing or evaluation process. Using the load-locked chamber in this manner allows the main processing chamber to be maintained at high or ultra-high vacuum pressure while sequentially processing hundreds or thousands of substrates without venting the processing chamber to the atmosphere.

[0051] Figures 2A-2C This is a simplified block diagram of a previously known substrate processing system 200, which includes a substrate processing chamber 210 and a load-locking chamber 220. The substrate processing chamber 210 may represent the substrate processing chamber 110, but for ease of illustration... Figure 2A SEM pillars 120 and other components of processing chamber 110 are not shown in Figure 2B. The substrate processing system 200 may also include additional components such as docking stations, one or more FOUPs and various transfer units (e.g., ETUs, ITUs and other robots), which are not shown in the figures for the sake of simplicity, as mentioned above.

[0052] like Figures 2A-2C As shown, the substrate processing chamber 210 may include a sample support element 240 that supports a sample 250 (e.g., a semiconductor wafer) during processing operations, in which the sample 250 is subjected to a beam of charged particles from an SEM column (not shown). The support element 240 and the sample 250 can represent... Figure 1 The support element 140 and sample 150 discussed in the article.

[0053] The load lock chamber 220 may also include a sample support element 260 for supporting the sample when the sample 250 is located within the load lock chamber. Each sample support element 240 and 260 may include an upper support surface 242, 262, and a lifting rod (not shown) to allow the sample to be lifted above the upper support surface so that the transfer unit can slide under the sample and transfer or remove the sample onto or from the support element, as is known to those skilled in the art.

[0054] To process sample 250 within processing chamber 210, the sample can first be transferred to load-lock chamber 220 (as indicated by the dashed arrow) and positioned on sample support 260, as shown in Figure 2. This operation can be performed by a first transfer unit, which removes sample 250 from the FOUP and transfers it into load-lock chamber 220, which is at atmospheric pressure. The chamber can then be evacuated to a suitable vacuum pressure, and a second transfer unit can transfer sample 250 from load-lock chamber 220 to processing chamber 210 (as shown in Figure 2). Figure 2B (As shown by the dashed arrow in the image), both chambers are kept in a vacuum state.

[0055] After processing, sample 250 can be transferred from processing chamber 210 back to load lock chamber 220 (e.g., Figure 2C (As shown by the dashed arrow in the image), while both chambers remain in a vacuum state.

[0056] In some previously known systems, the support element 240 may be an electrostatic chuck that applies a voltage to one or more electrodes disposed below the surface 242 to adsorb and flatten the sample 250 onto the support element 240. Figure 3A and 3B This is a simplified schematic diagram of a previously known electrostatic chuck 300, which may represent a support element 240, and some previously known sample evaluation systems use this device to support conductive samples, such as semiconductor wafers, in a vacuum chamber during the sample evaluation process.

[0057] First refer to Figure 3A The electrostatic chuck 300 includes a movable stage 310 connected to a support plate 320. The support plate 320 has a flat support surface 322 on which a sample 350 (e.g., a wafer such as a semiconductor wafer) can be placed for evaluation or other types of analytical operations.

[0058] The stage 310 can move the support plate 320 (and thus the sample 350) within the vacuum chamber 110 along the X, Y, and Z directions to directly position the region of interest on the sample under the field of view of a charged particle column, such as charged particle column 120. The plate 320 can be made of a dielectric material, such as ceramic, and one or more electrodes 324, 326 can be disposed below the surface 322. When the sample 350 is a semiconductor wafer or other conductive sample, a voltage can be applied to the electrodes 324, 326 to adsorb the sample onto the flat support surface 322, such as... Figure 3A As shown, the sample is fixed to the support plate 320 so that the sample will not shift or move otherwise when the worktable 310 moves the sample support within the vacuum chamber 110. Adsorbing the sample 350 in this manner can also advantageously flatten the sample, provided that the warpage of the sample 350 is within certain limits, to ensure accurate working distances between all areas of the sample.

[0059] The support plate 320 may also include multiple lifting rod holes 328 and a corresponding number of lifting rods 330 to facilitate the entry and exit of the sample 350 from the sample evaluation system. Figure 3A and 3B As shown, each lifting rod hole 328 can completely pass through the support plate 320. Furthermore, although in Figure 3A Or, as not shown in 3B, the lifting rod 330 can be fixedly connected to a portion of the worktable 310, allowing the lifting rod to move in the X and Y directions as the support plate 320 moves, while simultaneously allowing the worktable 310 to raise and lower the support plate 320 in the Z direction without moving the lifting rod 330. In this way, the support plate 320 can be lowered such that the distal end of each lifting rod 330 passes through its respective lifting rod hole 328, suspending the sample 350 above the upper surface 322 of the support plate 320, thereby forming a gap 340 between the upper surface 322 of the support plate 320 and the bottom surface of the sample 350, as shown. Figure 3A As shown. When the suction cup is fully lifted (e.g., to...), Figure 3B When in the position shown, each lifting rod 330 will retract into its respective lifting rod hole 328 in the support plate 320, and the sample 350 will sit stably on the upper surface 322.

[0060] exist Figure 3AWith the lifting rod 330 in the raised position, an ITU or similar substrate transfer device (not shown) can transfer the sample 350 into the vacuum chamber, place the sample on the lifting rod 330, and retract it from the vacuum chamber. Subsequently, the support plate 320 can be raised to place the sample 350 on the upper surface 322, allowing evaluation or other analyses of one or more areas of the sample, as described above. Once the evaluation process for a particular sample 350 is complete, the support plate can be lowered, raising the sample 350 onto the lifting rod 330, and the resulting gap 340 between the sample and the support surface 322 allows the ITU (not shown) to remove the sample 350 from the lifting rod and transfer it out of the chamber.

[0061] Although Figure 3A and 3B The cross-sectional view shows two lifting rod holes 328 and two corresponding lifting rods 330, but a typical electrostatic chuck 300 will include at least three lifting rod holes 328 and three lifting rods 330 spaced apart around the periphery of the support plate 320. For example, in some embodiments, the electrostatic chuck 300 may include three lifting rod holes 328 and three lifting rods 330 spaced apart at 120-degree angles.

[0062] Challenges in processing highly warped samples

[0063] like Figure 1 As shown in Figures 2 and 3A, 3B, the samples 150, 250, and 350 processed in systems 100 and 200 are thin, flat wafers, such as semiconductor or dielectric wafers. All of these samples have a certain degree of warpage (i.e., the sample exhibits a shape that is raised or recessed to some extent), where warpage is defined as the difference between the lowest point and the highest point of the sample when the sample is placed on a flat surface without being adsorbed or otherwise fixed to that surface.

[0064] Due to the use of non-silicon wafers and new manufacturing technologies, as well as the increasing size of semiconductors and other wafers year after year, the degree of warpage has generally increased, to the point that some wafers warp at least several hundred micrometers, while others warp to several millimeters. Some existing electrostatic chucks, such as the chuck 300 discussed above, cannot completely flatten the wafer when the warpage exceeds a certain threshold. For illustration, refer to... Figure 4A and 4B ,in Figure 4A This is a simplified cross-sectional view of the electrostatic chuck 300 supporting the warped sample 450 discussed above. Figure 4B This is an enlarged view of a portion of suction cup 300 and sample 450.

[0065] like Figure 4A and 4BAs shown, sample 450 is convex and warped. When the sample is placed on the upper surface 322 of the chuck, the distance between the outer edge of sample 450 and surface 322 is D. When a high voltage is applied to electrodes 324 and 326, the electrostatic chuck 300 can flatten a portion of sample 450. However, if the warping distance D is too large, the electrostatic chuck 300 cannot completely flatten the sample. In this case, when using a SEM instrument, such as system 100, to image or otherwise evaluate sample 450, the working distance between the column tip and the sample will vary at different locations on sample 450, which will adversely affect the accuracy of the obtained images.

[0066] The actual distance D by which a wafer cannot be fully flattened using a particular electrostatic chuck will depend on several factors, including but not limited to: the material used in the wafer, the size of the wafer, the model / type of the electrostatic chuck, and the voltage level applied to the electrodes. For some known electrostatic chucks, once the warpage of a particular wafer exceeds several hundred micrometers, it may not be possible to fully flatten the wafer using an acceptable voltage level.

[0067] As described above, for certain processing operations performed on wafers or other samples, it is important that the sample be perfectly flat. For example, as mentioned above, when imaging various locations on a wafer using a scanning electron microscope (SEM) tool, the working distance between the column tip and the sample must be precisely known. Therefore, for this purpose, the methods and systems described herein flatten the sample before performing processing operations (e.g., SEM imaging operations). As described in detail below, the embodiments disclosed herein can fix and flatten the sample to be processed under high or even ultra-high vacuum conditions in several different ways. In some embodiments, the sample is flattened in a load lock or similar chamber before being transferred to a processing chamber. In other embodiments, the sample is transferred to a main processing chamber and flattened in the main processing chamber before performing substrate processing operations (e.g., SEM imaging operations). In other embodiments, the processing chamber includes a main chamber region where sample processing is performed, and a separate chamber region isolated from the main chamber region where the sample is initially flattened. Details of these embodiments are described below.

[0068] Hybrid vacuum-electrostatic chuck carrier

[0069] In some embodiments, instead of placing the sample directly on a sample support within the processing and load-locking chamber, such as support elements 240 and 260, the sample is first placed on a suction cup carrier within the load-locking chamber, which is then placed on a support structure. This suction cup carrier can be used to fix and flatten the sample using vacuum adsorption and electrostatic adsorption techniques, and is referred to herein as a hybrid vacuum-electrostatic suction cup carrier. In operation, the hybrid suction cup carrier can initially fix and flatten the sample using its vacuum adsorption capacity under the pneumatic pressure conditions of the load-locking chamber. Then, the hybrid suction cup carrier can activate its electrostatic adsorption capacity to increase electrostatic force to further fix the sample, after which the load-locking chamber can be evacuated, allowing the sample to flatten and adhere to the hybrid suction cup carrier solely under electrostatic force. After the sample is fixed and flattened, the hybrid vacuum-electrostatic suction cup carrier and the sample can be transferred from the load-locking chamber to the main processing chamber via an ITU, and the sample can be processed on the hybrid suction cup carrier under vacuum pressure.

[0070] Figure 5A This is a simplified cross-sectional view of a sample support system 500, including a hybrid vacuum-electrostatic chuck carrier 520 (sometimes referred to herein as "chuck carrier 520") and a platform 510, according to certain embodiments. As shown, a sample 550 is placed on the upper surface 502 of the chuck carrier 520, and the chuck carrier is located on the upper surface 512 of the platform 510, which may be located in the load lock chamber or the main processing chamber, replacing support elements 260 or 240, respectively. Each surface 502 and 512 is generally planar and similar in shape but at least slightly larger than the sample 550.

[0071] Figure 5A The diagram shows two sets of lifting rods 504 and 506, a vacuum system 525, and a high-pressure system 530. Lifting rod 504 allows the sample to be raised above the upper support surface 502, enabling the transfer unit to slide under the sample and transfer it onto or off the suction cup carrier 520. Similarly, lifting rod 506 allows the suction cup carrier 520 to be raised above the platform 510, enabling the transfer unit to slide under the suction cup carrier and transfer the suction cup carrier and sample onto or off the platform 510.

[0072] like Figure 5B As shown, this figure is an enlarged view of a portion of the suction cup carrier 520, sample 550, and platform 510, with each lifting rod 504, 506 located within its respective lifting rod hole 505, 507. The lifting rod hole 507 completely penetrates the platform 510, while the lifting rod hole 505 completely penetrates both the platform 510 and the suction cup carrier 520.

[0073] The suction cup carrier 520 includes a plurality of vacuum channels 522 on its upper surface, which can be operatively coupled to a vacuum system 525 when the suction cup carrier is positioned on the platform 510. For example, a first vacuum line 524 extending from the vacuum system 525 to the platform 510 can be fluidly coupled to a second vacuum line 526 passing through the suction cup carrier 520 via a coupling element 528. Thus, when the vacuum system 525 is activated, each vacuum channel 522 is fluidly coupled to the vacuum system 525 and is able to apply a vacuum to the back side of the sample 550.

[0074] The suction cup carrier 520 also includes a series of electrodes 532, 534, which are operatively coupled to the high-voltage source 530 when the suction cup carrier is placed on the platform 510. The electrodes 532, 534 can be arranged in an alternating or other pattern, located directly below the upper surface 502, as is known to those skilled in the art, and can be driven with opposite charges (i.e., positive and negative) to generate an electrostatic field on the upper surface, thereby fixing and adsorbing the sample 550 onto the suction cup carrier. As shown, high-voltage lines 536, 538 extend from the high-voltage source 530 to the platform 510. Lines 536, 538 can be electrically coupled to the high-voltage lines 542, 544 passing through the suction cup carrier 520 via couplings 546, 548, respectively. Therefore, each series of electrodes 532, 534 is electrically coupled to the high-voltage system 530 and can generate an electrostatic force when the high-voltage source 530 is activated, adsorbing the sample 550 onto the suction cup carrier 520.

[0075] In operation, the suction cup carrier 520 initially adsorbs and flattens the sample 550 onto its surface by activating the vacuum system 525. Then, once the sample 550 is flattened onto the suction cup carrier 520, the high-voltage source 530 activates electrodes 532 and 534 to electrostatically adsorb the sample onto the suction cup carrier, while the vacuum applied by the vacuum system 525 is released. In this way, the suction cup carrier can flatten highly warped samples using its vacuum adsorption device, samples that cannot be completely flattened by electrostatic chuck alone. After the sample is adsorbed by electrostatic force, the suction cup carrier can then be transferred to the main processing chamber.

[0076] To better understand and appreciate how the hybrid vacuum-electrostatic chuck 520 can be used for flattened samples, such as highly warped substrates, for processing in substrate handling chambers evacuated to high vacuum pressure levels or lower, refer to [reference needed]. Figure 6 and Figures 7A-7I . Figure 6 This is a flowchart illustrating the steps of a method 600 for flattening and processing a warped substrate in certain embodiments. Figures 7A-7I This is a simplified cross-sectional view of a substrate processing system 700 according to certain embodiments, showing the process according to... Figure 6The method addresses different stages of warped substrate processing.

[0077] As shown in the figure, the substrate processing system 700 includes a main processing chamber 710 and a load-locking chamber 720, and relies on a hybrid vacuum-electrostatic chuck carrier 765 to hold the sample 750 when the sample is transferred between the load lock and the main processing chamber. The main processing chamber 710 can be similar to... Figure 1 and Figure 2A , 2B The chambers 110 and 210 are different, except that the worktable 740 is adjusted to receive the suction cup carrier 765, replacing the support elements 140 and 240. The load lock chamber 720 can be similar to the load lock chamber 220, except that the platform 760 replaces the substrate support 260. The suction cup carrier 520 can represent the suction cup carrier 765.

[0078] First refer to Figure 6 and Figure 7A Method 600 begins by transferring sample 750 to load lock chamber 720 and placing the sample on the upper support surface of hybrid vacuum-electrostatic chuck carrier 765. Figure 6 (Step 610). The suction cup carrier 765 can be, for example, the suction cup carrier 520 discussed above, so that the sample can be fixed to its upper surface using vacuum or electrostatic adsorption, or both. The adsorption carrier can be placed on any suitable adsorption technique or mechanism (e.g., a releasable latch) and mechanically adsorbed onto the platform 760. The platform 760 can be, for example, the platform 510 discussed above.

[0079] Platform 760 can simultaneously position and align the suction cup carrier and sample by rotating the sample and carrier to a specific angle, so that when the transfer unit lifts and places the carrier on the main chamber stage, the currently processed sample is in the same known position as previously processed samples and samples to be processed after the current sample. Platform 760 includes a vacuum connection 762 and a high-voltage connection 764, which can respectively connect the vacuum system (in Figure 7A (Not shown) and a high-voltage source (also not shown) are coupled to corresponding connections on the suction cup carrier 765 when it is fixed to the platform 760. For example, vacuum connection 762 may represent vacuum line 524 and vacuum coupler 528 that couple vacuum system 525 to vacuum line 526 within the suction cup carrier. Similarly, high-voltage connection 764 may represent high-voltage lines 536, 538 and high-voltage couplers 546, 548 that couple high-voltage source 530 to voltage lines 542, 544 within the suction cup carrier.

[0080] Although Figure 7ANot shown, but the transfer can be performed by an ETU that lifts sample 750 from a docking station (e.g., from a FOUP within the storage area of ​​system 700) and places the sample on a lifting rod (e.g., lifting rod 504) protruding from the upper surface of the suction cup carrier 765 within the load lock chamber. The lifting rod can then be lowered so that the sample is supported by the upper surface of the suction cup carrier 765, as... Figure 7A As shown. This initial transfer step can be performed when the load lock chamber 720 is at atmospheric pressure, as shown by the dashed background within chamber 720.

[0081] Next, following the indication of arrow 770, the vacuum system can be activated to create a vacuum suction at the bottom of sample 750. Figure 6 (Step 620). With the load lock chamber pressure higher than the vacuum pressure, a vacuum is applied to the back of the sample 750, causing the sample to adhere to the upper surface of the suction cup carrier 765, and as... Figure 7B The sample is flattened as shown. When a vacuum is applied to the back of sample 765 (while the load-locking chamber remains at atmospheric pressure), it can be determined according to... Figure 7C Arrow 772 activates the high-voltage source to increase electrostatic force, further securing sample 750 onto suction cup support 765. Figure 6 (Step 630).

[0082] The load lock chamber 720 can then be evacuated to match the pressure of the main processing chamber 710 (e.g., pressure equal to or between high vacuum and ultra-high vacuum pressure), and as... Figure 7D The absence of the middle arrow 770 indicates that the vacuum system for adsorbing sample 750 onto the suture carrier 765 is shut off. During this period, the high voltage applied to the electrodes remains constant (arrow 772) so that the electrostatic force becomes the sole force adsorbing sample 750 onto the suture carrier. Figure 6 (Step 640).

[0083] As described above, vacuum chucks can sometimes flatten highly warped wafers that conventional electrostatic chucks cannot completely flatten. However, when a sample is vacuum-adsorbed onto the chuck carrier 765, the electrostatic adsorption portion of the chuck carrier 765 can maintain the sample in a flattened state. Therefore, by initially using a vacuum chuck to adsorb the sample 750 and then switching the adsorption force to electrostatic force, it is possible to hold some highly warped samples in a flattened state that cannot be maintained by electrostatic force alone.

[0084] Next, the transfer unit 780 picks up the suction cup carrier 765 and electrostatically attaches the sample 750 to the suction cup carrier, such as... Figure 7E As shown ( Figure 6Step 650), and transfer the suction cup carrier to the stage 740 in the main processing chamber 710 (as described above, it can be under high vacuum or lower pressure), such as Figure 7F As shown ( Figure 6 Step 660). Although Figure 7E Not shown, but in order for the transfer unit 780 to transfer the suction cup carrier from the load lock chamber 720, the suction cup carrier is first raised above the surface of the platform 760 by a lifting rod (e.g., lifting rod 506). Similarly, in order for the transfer unit to transfer the suction cup carrier onto the worktable 740, the suction cup carrier is placed on a lifting rod extending above the surface of the worktable 740, the transfer unit retracts, and then the lifting rod slowly descends into the body of the worktable 740, placing the suction cup carrier 765 (and sample 750) onto the worktable 740, as shown. Figure 7G As shown.

[0085] During the transfer of the suction cup carrier 765 to the stage 740, the suction cup carrier is disconnected from the voltage source 772, moved into the processing chamber 710 and aligned with the stage 740 so that the two high-voltage lines (indicated by a single dashed line 742) can be electrically coupled to their corresponding lines (e.g., lines 536, 538) in the suction cup carrier. Subsequently, a high-voltage connection is established to the voltage line 742 (indicated by arrow 774) to maintain the electrostatic adsorption of the sample 750 onto the suction cup carrier and thus keep the sample 750 in its flattened state.

[0086] Next, sample 750 can be processed within the main chamber 710 under high vacuum (or even higher) pressure, while a high voltage is applied to the electrodes to maintain the sample's flattened state. Figure 6 (block 670). In the illustrated embodiment, processing sample 750 may include imaging multiple locations on the sample using a scanning electron microscope, but as previously mentioned, in other embodiments, the main chamber 710 may be a different type of processing chamber, and the substrate processing operation may not be an imaging operation.

[0087] After processing, the transfer unit picks up the suction cup carrier 765 (with sample 750 on its upper surface) and transfers it back to the load lock chamber 720, as follows. Figure 7H As shown, when both the main processing chamber 710 and the load lock chamber 720 are in a vacuum state ( Figure 6 (Step 680). The load-locking chamber 720 can then be vented to the atmosphere. Figure 6 (Step 690) prepares the sample for transfer from the load lock chamber to subsequent processing steps. In step 680, it is no longer necessary to apply voltage to maintain the electrostatic attraction, so the sample 750 may return to its initial warped state, such as... Figure 7I As shown.

[0088] Method 600 can be repeated on the next sample.

[0089] exist Figures 7A-7I In the illustrated embodiment, when the suction cup carrier 765 is transferred from the platform 760 to the worktable 740, the connection between the electrodes within the suction cup carrier and the high-voltage source is temporarily disconnected. For example, when the transfer unit picks up the suction cup carrier 765 from the platform 760 in step 650, the high-voltage connection 772 is temporarily interrupted until the transfer unit places the suction cup carrier onto the worktable 740 in step 660 to form a high-voltage connection 774, at which point the connection is restored. However, the electrodes within the suction cup carrier 765 (e.g., a series of electrodes 532, 534) can be designed to have sufficient mass to easily accumulate enough charge on the electrodes, ensuring that the sample 750 remains adsorbed by the suction cup carrier during the transfer process.

[0090] In other embodiments, the transfer unit may include a high-voltage connection that mates with a high-voltage line in the chuck carrier to provide a continuous high voltage level to the electrodes in the chuck carrier during the transfer process.

[0091] Hybrid vacuum-electrostatic chucking in main chamber

[0092] In some embodiments, the main processing chamber may include a sample support capable of securing and flattening the sample, while also functioning as a vacuum chuck and an electrostatic chuck. This sample support is referred to herein as a hybrid vacuum-electrostatic chuck (or simply "hybrid chuck"). The hybrid chuck can initially utilize its vacuum adsorption function to secure and flatten the sample when the main chamber is at atmospheric pressure. Next, the hybrid adsorption can activate its electrostatic adsorption capability, adding electrostatic forces to the sample to further secure it. The main chamber can then be evacuated to a vacuum, making electrostatic force the sole technique for flattening and adsorbing the sample onto the hybrid chuck, allowing the sample to be processed within the main chamber at the desired vacuum pressure.

[0093] Figure 8A This is a simplified cross-sectional view of the sample support system 800, including a hybrid vacuum-electrostatic chuck 820 (sometimes referred to herein as "hybrid chuck 820") and a stage 810, according to certain embodiments. The hybrid chuck 820 may be similar to that described above. Figure 5A and 5BThe mixing suction cup carrier 520 discussed herein is simply a mixing suction cup 820 directly connected to the stage 810 in the processing chamber, rather than being transferred between the processing chamber and the load lock chamber via a transfer unit. Therefore, the mixing suction cup 820 includes a set of lifting rods 804 for lifting the sample relative to the upper support surface 802 of the suction cup, instead of two separate sets of lifting rods 504 and 506 associated with the mixing suction cup carrier 520. As shown, the sample 850 is placed on the upper surface 802 of the mixing suction cup 820, and the suction cup is mounted on the stage 810, which is movable along the X, Y, and Z axes of the sample processing chamber.

[0094] Figure 8A The image also shows a set of lifting rods 804, a vacuum system 825, and a high-pressure system 830. The lifting rods 804 allow the sample to be raised above the upper support surface 802 so that the transfer unit can slide under the sample and transfer or remove the sample onto or from the mixing chuck 820. (Reference) Figure 8A and Figure 8B ( Figure 8B (Extended view of part of the mixing suction cup 820), sample 850 and worktable 810, each lifting rod 804 is located in its respective lifting rod hole 805, which fully penetrates the platform and the mixing suction cup 820.

[0095] The mixing chuck 820 includes a plurality of vacuum channels 822 on its upper surface, which can be operatively connected to a vacuum system 825 when the mixing chuck is placed on the platform 810. For example, a first vacuum line 824 extending from the vacuum system 825 to the platform 810 can be fluidly connected via a coupling 828 to a second vacuum line 826 passing through the mixing chuck 820. Thus, each vacuum channel 822 is fluidly connected to the vacuum system 825 and is operable to apply a vacuum to the rear surface of the sample 850 when the vacuum system 825 is activated.

[0096] The mixing chuck 820 also includes a series of electrodes 832, 834, which are operatively connected to a high-voltage source 830 when the chuck is placed on the platform 810. Electrodes 832, 824 may be arranged alternately or in other patterns below the upper surface 802, as described above for electrodes 532, 534. As shown, high-voltage lines 836, 838 extend from the high-voltage source 830 to the platform 810. Lines 836, 838 can be electrically connected, respectively, to the high-voltage lines 842, 844 passing through the mixing chuck 820 via couplings 846, 848. Thus, each series of electrodes 832, 834 is electrically connected to the high-voltage system 830 and is operable when the high-voltage source 830 is activated to generate electrostatic force to adsorb the sample 850 onto the mixing chuck.

[0097] To better understand and appreciate this implementation method, please refer to [link / reference]. Figure 9 andFigures 10A-10D ,in Figure 9 This is a flowchart depicting a method 900 related to certain implementations, used for flattening and processing a warped substrate. Figures 10A-10D It is based on Figure 9 A simplified cross-sectional view of the substrate processing system 1000 that flattens and processes the warped substrate 1050 at different stages according to the method.

[0098] As shown in the figure, the substrate processing system 1000 includes a main processing chamber 1010, which performs the same substrate processing operations as chambers 110 and 210 described above, and therefore contains many of the same components. However, at the sample support 140 or 240, the substrate processing system 1000 includes a mixing vacuum-electrostatic chuck 1020, which can hold the sample 1050 within the processing chamber during substrate processing operations. The mixing chuck can be mounted on a stage 1040 within the chamber 1010, which can move the mixing chuck and sample 1050 within the processing chamber 1010 so that different portions of the sample are directly below the field of view of the SEM column. For this purpose, the stage 1040 can move the mixing chuck and sample 1050 left and right and back and forth within the chamber 1010 (i.e., along the X and Y axes), and can also raise and lower the mixing chuck and sample along the Z axis.

[0099] The worktable 1040 also includes a vacuum connection 1062 and a high-pressure connection 1064, which can be used to connect the vacuum system (in the process of fixing the mixing suction cup 1020 to the worktable 1040) when the mixing suction cup 1020 is fixed to the worktable 1040. Figure 10A The connections (not shown) to the high-voltage source (also not shown) are connected to the corresponding connections on the mixing chuck. For example, vacuum connection 1062 could represent vacuum line 824 and vacuum coupler 828, connecting vacuum system 825 to vacuum line 826 within the mixing chuck. Similarly, high-voltage connection 1064 could represent high-voltage lines 836, 838 and high-voltage couplers 846, 848, connecting high-voltage source 830 to voltage lines 842, 844 within the mixing chuck, respectively.

[0100] See Figure 9 and Figure 10A Method 900 begins by transferring sample 1050 into substrate processing chamber 1010 and placing the sample on the upper support surface of mixing chuck 1020. Figure 9 (Step 910). The hybrid chuck 1020 can be the hybrid chuck 820 discussed above, thus allowing the sample to be secured to its upper surface using one or both vacuum and electrostatic adsorption. The sample 1050 can be a thin semiconductor wafer. The system 1000 can process hundreds or thousands of samples 1050 sequentially, some of which may have high warpage, such as... Figure 10A As shown.

[0101] Although Figure 10ANot shown, but the transfer can be performed by an ETU that lifts sample 1050 from the load-locking chamber and places it on a protruding lifting rod (e.g., lifting rod 804) positioned above the upper surface of the mixing chuck 1020 within the substrate processing chamber 1010. The lifting rod can then be lowered (or the stage 1040 can be raised) so that the sample is supported by the upper surface of the chuck 1020, as... Figure 10A As shown. This initial transfer step can be performed in the processing chamber 1010 under atmospheric pressure (as shown by the dashed background of chamber 1010).

[0102] Next, we can do as follows Figure 10B As shown, the vacuum system is activated via arrow 1070 to generate a vacuum suction at the bottom of sample 1050. Figure 9 (Step 920). Applying a vacuum to the back of sample 1050 will adsorb the sample onto the upper surface of the mixing chuck 1020 and flatten the sample, as shown. Figure 10B As shown. When a vacuum is applied to the back of sample 1050 (while the load lock chamber remains at atmospheric pressure), it can be as follows. Figure 10C Arrow 1072 indicates the activation of the high-voltage source to increase electrostatic force and further fix the sample 1050 to the suction cup carrier 1020. Figure 9 (Step 930).

[0103] Processing chamber 1010 can be evacuated to a vacuum (e.g.) Figure 10C (As shown by the missing dashed background), the required substrate processing pressure (e.g., the pressure between high vacuum and ultra-high vacuum) is achieved, and as... Figure 10C As indicated by the missing arrow 1070, the vacuum system adsorbing sample 1050 to the chuck carrier 1020 can be shut off. During this time, the high voltage applied to the electrodes remains constant (arrow 1072), making electrostatic force the sole force adsorbing sample 1050 to the mixing chuck. Figure 9 (Step 940).

[0104] During this stage, sample 1050 can be processed within processing chamber 1010 while a high voltage is still applied to the electrodes to maintain the sample's flattened state. Figure 9 (block 950). Initially, a vacuum suction cup is used to adsorb sample 1050, and then in method 900, the adsorption force is converted into an electrostatic force, which enables certain highly warped samples to remain flat, samples that cannot be flattened by electrostatic force alone.

[0105] After processing, high-pressure source 1072 was shut off, and the processing chamber was vented to the atmosphere. Figure 9 (Step 960), as follows Figure 10DAs shown. The sample can then be lifted from the upper surface of the mixing suction cup 1020 via the lifting rod, and the ITU (not shown) can pick up the sample 1050 and transfer it back to the load lock chamber (not shown), while both the main processing chamber 1010 and the load lock chamber 1020 are in the atmosphere. Figure 9 (Step 970).

[0106] Method 900 can be repeated on the next sample.

[0107] Processing chamber with main chamber and separate auxiliary area

[0108] In other embodiments, the main processing chamber may include a separate auxiliary region or chamber that can be isolated from the main chamber. The system may include a substrate support capable of securing and flattening the sample, acting as both a vacuum chuck and an electrostatic chuck, similar to the description above regarding a hybrid vacuum-electrostatic chuck. However, instead of repeatedly evacuating the main chamber and then pumping it to the required vacuum pressure for processing, the substrate support (stage) can move the hybrid chuck and sample between the main processing chamber and the auxiliary region during the processing of a series of samples. The auxiliary region can be much smaller than the main processing chamber and can then be isolated from the main processing chamber and vented to the atmosphere.

[0109] Once positioned within the auxiliary region, the mixing chuck utilizes its vacuum adsorption properties to fix and flatten the sample while the auxiliary chamber is at atmospheric pressure. Next, the mixing chuck activates its electrostatic adsorption function, increasing electrostatic force to fix the sample. The auxiliary region can then be evacuated, making the electrostatic force the sole force for flattening and adsorbing the sample onto the mixing chuck. Because the volume of the auxiliary region is much smaller than the main processing chamber, the required vacuum pressure can be reached more quickly, thereby increasing the processing throughput of multiple wafers. The mixing chuck can then be moved back to its processing position within the main chamber and processed under the required vacuum pressure. For illustration, see reference... Figure 11 and 12A Up to 12G, of which Figures 12A-12G This is a flowchart describing the steps related to method 1100, used for flattening and processing a warped substrate according to certain embodiments, while Figure 11 This is a simplified cross-sectional view of a substrate processing system 1200 that flattens and processes a warped substrate 1250 at different stages according to certain embodiments. This method... Figure 12A Listed in.

[0110] As shown in the figure, the substrate processing system 1200 includes a main processing chamber 1210, which may contain many of the same elements as the chambers 110 or 210 discussed above and perform the same general substrate processing operations. The substrate processing system 1200 also includes a hybrid vacuum-electrostatic chuck 1220 and a separate auxiliary chamber or volume that can be isolated from the environment of the main processing chamber 1210.

[0111] A hybrid vacuum-electrostatic chuck 1220 can hold the sample 1250 within the processing chamber during substrate processing operations and can be placed on a stage 1240 within the chamber 1210, which can move the hybrid chuck and sample 1250 within the processing chamber. The hybrid chuck 1220 and stage 1240 can be similar to the hybrid chuck 1020 and stage 1040 described above. However, in this embodiment, the stage 1040 can move the hybrid chuck to different positions within the processing chamber 1210 to precisely position different portions of the sample within the field of view of the SEM column, and can also move the hybrid chuck into or out of the auxiliary area 1030.

[0112] As shown, the worktable 1240 includes a vacuum connection 1262 and a high-voltage connection 1264, which can respectively connect the vacuum system (in...) Figure 11 (Not shown) and a high-voltage source (also not shown) are coupled to corresponding connections when the mixing chuck 1220 is fixed to the stage 1240. For example, vacuum connection 1262 may represent vacuum line 824 and vacuum coupler 828, which connect vacuum system 825 to vacuum line 826 within the mixing chuck. Similarly, high-voltage connection 1264 may represent high-voltage lines 836, 838 and high-voltage couplers 846, 848, which connect high-voltage source 830 to voltage lines 842, 844 within the mixing chuck.

[0113] refer to Figure 11 and 12A Method 1100 begins by transferring sample 1250 to substrate processing chamber 1210 and placing the sample on the upper support surface of mixing chuck 1220. Figure 12A (Step 1110). The hybrid chuck 1220 can be the hybrid chuck 820 discussed above, thus enabling the use of vacuum or electrostatic adsorption, or a combination of both, to fix the sample to its upper surface. The sample 1250 can be a thin semiconductor wafer, the degree of which may vary.

[0114] Despite Figure 12ANot shown, the transfer can be performed by an ETU that picks up sample 1250 from the load-lock chamber and places the sample on protruding lifting rods (e.g., lifting rod 804) extending beyond the upper surface of the mixing chuck 1220 within the processing chamber 1210. The lifting rods can then be lowered (or the stage 1240 can be raised) so that the sample is supported by the upper surface of the chuck 1220, as... Figure 12B As shown. This initial transfer step can be performed under vacuum pressure in both the load lock chamber and the substrate processing chamber 1210.

[0115] Next, the workbench 1240 moves the sample from the main chamber 1210 to the auxiliary area 1230, as follows: Figure 11 As shown ( Figure 11 (Step 1120). Moving the stage in step 1120 may include moving the stage along one or both of the X-axis and Y-axis until the stage is properly positioned below the auxiliary area 1230, and then raising the stage to allow at least a portion of the sample 1250 and the mixing suction cup 1220 to enter the auxiliary area 1230, thus isolating the auxiliary area from the environment of the main processing chamber 1210. Sealing the auxiliary area from the main processing chamber can be achieved using any suitable techniques or mechanisms known to those skilled in the art.

[0116] Auxiliary area 1230 can then exhaust to the atmosphere ( Figure 12C (Step 1130), while the main processing chamber is kept in a vacuum, such as Figure 12D As shown. The vacuum adsorption section of the hybrid suction cup 1220 can be activated, as indicated by arrow 1270. Figure 11 As shown, a vacuum attraction is generated at the bottom of sample 1250. Figure 12D (Step 1140). A vacuum is applied to the back of sample 1250 to adsorb the sample onto the upper surface of mixing chuck 1220 and flatten the sample, as shown. Figure 12E As shown.

[0117] When a vacuum is applied to the back of sample 1250 (and auxiliary region 1030 remains at atmospheric pressure), a high-pressure source can be activated, as indicated by arrow 1272. Figure 11 As shown, to increase electrostatic force, the sample 1250 is further fixed to the mixing chuck 1220. Figure 12F (Step 1150).

[0118] Auxiliary area 1230 can then be evacuated to a vacuum (e.g.) Figure 12F (As shown by the missing dashed background in the image), the vacuum system reaches the same vacuum pressure as the substrate processing system 1210, and the vacuum system that adsorbs the sample 1250 onto the mixing chuck 1220 can be shut off, as shown in the image. Figure 11The missing arrow 1270 indicates this. During this period, the high voltage applied to the electrode is maintained (arrow 1272), therefore the electrostatic force becomes the sole force adsorbing the sample 1250 onto the mixing chuck 1220. Figure 11 (Step 1160).

[0119] Next, the workbench 1240 can be moved back to the main processing area of ​​the chamber 1210. Figure 12G Step 1170), as follows Figure 11 As shown, sample 1250 can be processed within processing chamber 1210 while high voltage is still applied to the electrodes to keep the sample in a flat state. Figure 11 (Step 1180). As described in the earlier embodiments above, sample 1250 is initially adsorbed using a vacuum suction cup, and then in method 1100 the adsorption force is switched to electrostatic force, so that some highly warped samples can remain flat, which cannot be flattened by electrostatic force alone.

[0120] After processing, the high-pressure source 1172 can be turned off, the sample can be lifted by the lifting rod to the upper surface of the mixing suction cup 1220, and the ITU (not shown) can pick up the sample and transfer it back to the load lock chamber (not shown), while both the main processing chamber 1210 and the load lock chamber 1220 are in a vacuum. Additional embodiments (Step 1190).

[0121] Method 1100 can then be repeated for the next sample.

[0122] ​

[0123] The foregoing description uses specific nomenclature for illustrative purposes to provide a thorough understanding of the described embodiments. However, it will be apparent to those skilled in the art that the specific details are not necessary for the purpose of implementing the described embodiments. For example, while the examples discussed above sometimes refer to the sample processing chamber as a scanning electron microscope tool, the embodiments disclosed herein can be used in many other types of sample processing chambers in which a substrate or other type of sample needs to be fixed and / or flattened before processing under vacuum conditions, as will be understood by those skilled in the art. As another example, while the illustrated examples above all employ the vacuum chuck function to fix and flatten the sample when it is located in a sealed area within the chamber or at another atmospheric pressure (i.e., 760 torr), the embodiments are not limited to this. In other embodiments, the sample can be initially fixed and flattened by the vacuum chuck at pressures below 760 torr. In fact, those skilled in the art will recognize that the key factor is the difference between the pressure generated by the vacuum chuck on the lower surface of the sample and the pressure of the chamber / environment in which the sample is located. When the sample is in a high vacuum environment, the vacuum chuck cannot fully fix and flatten the sample. However, this suction cup can fix and flatten certain samples at pressure levels below 760 torr, such as those that can be considered to be in the “rough vacuum range” (e.g., pressures below 760 torr but above 25 torr). Those skilled in the art will further recognize that a large pressure difference between the vacuum pressure generated on the lower surface of the sample and the chamber / ambient pressure on the upper surface of the sample can fix and flatten samples with a high degree of warping, whereas a smaller pressure difference between the opposing surfaces of the sample might not be sufficient to fix and flatten them.

[0124] Furthermore, although different embodiments have been disclosed above, the specific details of particular embodiments may be combined in any suitable manner without departing from the spirit and scope of this disclosure. Moreover, many modifications and variations can be made by those skilled in the art based on the foregoing teachings; therefore, it should be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of this disclosure.

[0125] The embodiments shown in this disclosure can be implemented in most cases using electronic components and circuits known to those skilled in the art, but these details will not be explained further beyond what is necessary to understand and appreciate the basic concepts of this disclosure, and will not confuse or distract from the teachings of this disclosure.

[0126] Furthermore, the methods mentioned in the above specification should be adapted to suitably apply to systems capable of executing the methods, and should be adapted to suitably apply to computer program products storing instructions that, upon execution, will cause the methods to be executed. Similarly, the systems mentioned in the above specification should be adapted to suitably apply to methods that the system may execute, and should be adapted to suitably apply to computer program products that can be executed by the system; and the computer program products mentioned in the above specification should be adapted to suitably apply to methods that may be executed when executing instructions stored in the computer program product, and should be adapted to suitably apply to systems configured to execute instructions stored in the computer program product.

Claims

1. A method for processing a substrate in a processing chamber, the processing chamber comprising a main region and an auxiliary region that can be isolated from the environment of the main region, the method comprising: When the main region is under vacuum pressure, the substrate is transferred to the main region of the processing chamber and placed on the upper surface of the substrate holder, wherein the substrate holder includes one or more vacuum channels disposed on the upper surface and one or more electrodes disposed in the substrate holder near the upper surface. The substrate holder is moved within the processing chamber, causing the substrate to move from the main region to the auxiliary region; Seal the auxiliary area from the main area and increase the pressure within the auxiliary area; When the substrate is located in the auxiliary area, the substrate is adsorbed and flattened into the substrate holder by applying a vacuum to one or more vacuum channels; When the substrate is located in the auxiliary area and is adsorbed to the substrate holder through one or more vacuum channels, a voltage is applied to one or more electrodes to further adsorb the substrate to the substrate holder using electrostatic force. and When the substrate is attracted to the substrate holder by the electrostatic force, the substrate is moved from the auxiliary area back to the main area and the substrate is processed in the main area with vacuum pressure.

2. The method for processing a substrate as claimed in claim 1, wherein the auxiliary region is directly connected to the cover of the substrate processing chamber.

3. The method for processing a substrate as claimed in claim 1, the method further comprising, after processing the substrate under vacuum conditions in the main region, stopping the application of the voltage so that the substrate is no longer attracted to the substrate holder by the electrostatic force, and transferring the substrate out of the processing chamber.

4. The method of processing a substrate as claimed in claim 1, wherein the processing chamber comprises a scanning electron microscope, and processing the substrate in the processing chamber comprises imaging the substrate using the scanning electron microscope.

5. The method of processing a substrate as claimed in claim 1, wherein the warpage of the substrate between the lowest and highest points on the substrate is at least 1.0 mm.

6. The method for processing a substrate as claimed in claim 1, wherein the vacuum pressure for processing the substrate in the processing chamber is a high vacuum pressure or lower.

7. The method of processing a substrate according to any one of claims 1 to 6, wherein increasing the pressure in the auxiliary region comprises discharging the auxiliary region into the atmosphere.

8. The method of processing a substrate as claimed in claim 7, the method further comprising, after using electrostatic force to attract the substrate to the substrate holder in the auxiliary region, and before moving the substrate from the auxiliary region back to the main region, evacuating the auxiliary region to a vacuum pressure while continuing to attract the substrate to the substrate holder using the electrostatic force.

9. A system for processing a substrate, the system comprising: A substrate processing chamber having a main processing area and an auxiliary area that can be isolated from the environment of the main processing area; A substrate support is disposed within the substrate processing chamber and includes one or more vacuum channels disposed on its upper surface and one or more electrodes disposed in the substrate support near the upper surface. A worktable, the worktable being operatively coupled for moving the substrate support between the main processing area and the auxiliary area within the substrate processing chamber; At least one processor and at least one memory coupled to said at least one processor, said at least one memory including a plurality of computer-readable instructions that, when executed by said at least one processor, drive the system to perform: When the main region is under vacuum pressure, the substrate is transferred to the main region of the processing chamber and placed on the upper surface of the substrate holder, wherein the substrate holder includes one or more vacuum channels disposed on the upper surface and one or more electrodes disposed in the substrate holder near the upper surface. The substrate holder is moved within the processing chamber to move the substrate from the main region to the auxiliary region; Seal the auxiliary area from the main area and increase the pressure within the auxiliary area; When the substrate is located in the auxiliary area, the substrate is adsorbed and flattened into the substrate holder by applying a vacuum to the one or more vacuum channels; When the substrate is located in the auxiliary area and is adsorbed to the substrate holder through the one or more vacuum channels, a voltage is applied to the one or more electrodes to further adsorb the substrate to the substrate holder using electrostatic force; and When the substrate is attracted to the substrate holder by the electrostatic force, the substrate is moved from the auxiliary area back to the main area, and the substrate is processed in the main area with vacuum pressure.

10. The system for processing a substrate as claimed in claim 9, wherein increasing the pressure in the auxiliary region comprises discharging the auxiliary region into the atmosphere.

11. The method of processing a substrate as claimed in claim 10, wherein the computer-readable instructions further include, when executed by the processor, instructions to cause the system to evacuate the auxiliary region to a vacuum pressure after electrostatically attracting the substrate to the substrate holder and before moving the substrate from the auxiliary region back to the main region, while continuing to attract the substrate to the substrate holder with the electrostatic force.

12. The system for processing a substrate as claimed in claim 9, wherein the computer-readable instructions further include, when executed by the processor to cause the system to process the substrate in the main processing area under vacuum conditions, instructions to: stop applying the voltage, to prevent the substrate from being attracted to the substrate holder by the electrostatic force, and to transfer the substrate out of the substrate processing chamber.

13. The system for processing a substrate as claimed in claim 9, wherein the processing chamber includes a scanning electron microscope, and processing the substrate in the substrate processing chamber includes imaging the substrate using the scanning electron microscope.

14. The system for processing a substrate as claimed in claim 9, wherein the vacuum pressure at which the substrate is processed in the substrate processing chamber is a high vacuum pressure or lower.

15. The system for processing a substrate as claimed in any one of claims 9 to 14, wherein the auxiliary region is directly connected to the cover of the substrate processing chamber.

16. A non-transitory computer-readable memory, the memory being used to store instructions for a processing substrate within a processing chamber, the instructions comprising: When the main area of ​​the processing chamber is under vacuum pressure, the substrate is transferred to the main area of ​​the processing chamber and placed on the upper surface of the substrate holder, wherein the substrate holder includes one or more vacuum channels disposed on the upper surface and one or more electrodes disposed in the substrate holder near the upper surface; The substrate holder is moved within the processing chamber, causing the substrate to move from the main region to the auxiliary region; Seal the auxiliary area from the main area and increase the pressure within the auxiliary area; When the substrate is located in the auxiliary area, the substrate is adsorbed and flattened into the substrate holder by applying a vacuum to one or more vacuum channels; When the substrate is located in the auxiliary area and is adsorbed to the substrate holder through one or more vacuum channels, a voltage is applied to one or more electrodes to further adsorb the substrate to the substrate holder using electrostatic force. and When the substrate is attracted to the substrate holder by the electrostatic force, the substrate is moved from the auxiliary area back to the main area and processed with vacuum pressure in the main area.

17. The non-transient computer-readable memory of claim 16, wherein increasing the pressure within the auxiliary region comprises venting the auxiliary region to the atmosphere.

18. The method of processing a substrate as claimed in claim 7, wherein the computer-readable instructions further include, when executed by the processor, instructing the system to electrostatically attract the substrate to the substrate holder in the auxiliary region, and before moving the substrate from the auxiliary region back to the main region, to evacuate the auxiliary region to a vacuum pressure while continuing to electrostatically attract the substrate to the substrate holder.

19. The non-transitory computer-readable memory of claim 16, wherein the processing chamber includes a scanning electron microscope, and processing of the substrate in the processing chamber includes imaging the substrate using the scanning electron microscope.

20. The non-transitory computer-readable memory of any one of claims 16 to 19, wherein the warpage of the substrate between the lowest and highest points on the substrate is at least 1.0 mm.

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