Calculating wafer thickness from wafer mapping process

Abstract

A method of operating a substrate processing system, the substrate processing system including a substrate processing chamber, a substrate storage container, and a robot configured to select a substrate from the substrate storage container and transfer the selected substrate into the substrate processing chamber, the method comprises the following steps: detecting the lower edge and the upper edge of the substrate; calculating a thickness of the substrate based on the detected lower edge and the detected upper edge of the substrate; comparing the calculated thickness of the substrate with an expected thickness of the substrate; and (i) if the calculated thickness matches the expected thickness, controlling the robot to transfer the substrate into the substrate processing chamber, and (ii) if the calculated thickness does not match the expected thickness, generating an alert indicating a thickness mismatch.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority and benefit of U.S. Patent Application No. 18 / 071,400, filed on November 29, 2022, the entire disclosure of which is incorporated herein by reference. Background Art

[0003] The fabrication of semiconductor devices generally involves many different processing steps, which are performed by a variety of different types of tools in a semiconductor manufacturing facility. For example, to complete the fabrication of an integrated circuit on a semiconductor wafer, the wafer may be transferred to and processed by a set of tools that includes chemical vapor deposition tools, physical vapor deposition tools, etching tools, chemical mechanical polishing tools, lithography tools, and metrology tools, among others.

[0004] Historically, semiconductor manufacturers generally processed wafers of a particular diameter (e.g., 200 mm or 300 mm wafers) in a set of tools specifically designed to operate on wafers of that diameter, and all wafers of that diameter had the same thickness. For example, all 200 mm wafers processed by a set of tools might be 700 μm thick, while all 300 mm wafers processed by another set of tools might be 775 μm thick. Thus, any given tool was generally only used to process wafers of a particular known thickness.

[0005] However, in recent years, various semiconductor manufacturers have begun processing substrates such as silicon wafers to form many different types of integrated circuits and devices, some of which are fabricated on semiconductor wafers of different thicknesses. For example, a semiconductor manufacturer might produce some products on a set of 200 mm silicon wafers that are 700 μm thick, while other products are produced on another set of 200 mm silicon wafers that are 300 μm thick, and still other products are produced on a third set of 200 mm silicon wafers that are 1,400 μm thick.

[0006] In a manufacturing facility, a given processing tool can be set up to accept and process each group of wafers in a first group (700 - μm - thick wafers), a second group (300 - μm - thick wafers), and a third group (1,400 - μm - thick wafers), but adjustments may be required to enable the tool to properly process each different - thickness wafer. If the necessary adjustments are not made correctly, the wafers may be damaged when transferred to or processed within the tool, or the steps associated with processing the wafers within the tool may not be performed correctly.

[0007] To prevent wafers of the wrong thickness from being introduced into a particular tool, some semiconductor manufacturers require operators to manually control the settings of the tool to configure the tool for the appropriate wafer thickness to be processed by the tool. This method is prone to human error. Summary of the Invention

[0008] Embodiments of the present disclosure provide a method and system for automatically detecting the thickness of a sample before the sample is transferred to an evaluation tool. Some embodiments can generate an alert or signal in the case where the sample is thicker or thinner than the thickness set for the tool to handle, and the alert or signal indicates a mismatch between the actual thickness and the expected thickness of the sample to be transferred to the tool. In some embodiments, the tool can respond to the signal, for example, prevent the sample from being transferred to the tool, or perform one or more adjustments within the tool to set the tool to accept and process a sample with the actually measured thickness. Although embodiments of the present disclosure can be used to detect the thickness of various different types of samples, some embodiments are particularly applicable to detecting the thickness of samples such as semiconductor wafers or similar specimens.

[0009] In some embodiments, a method of operating a substrate processing system is provided. The substrate processing system can include a substrate processing chamber, a substrate storage container, and a robot configured to select a substrate from the substrate storage container and transfer the selected substrate into the substrate processing chamber. The method includes: detecting a lower edge and an upper edge of the substrate; calculating the thickness of the substrate based on the detected lower edge and the detected upper edge of the substrate; comparing the calculated thickness of the substrate with the expected thickness of the substrate; and (i) if the calculated thickness matches the expected thickness, controlling the robot to transfer the substrate into the substrate processing chamber, and (ii) if the calculated thickness does not match the expected thickness, generating an alert indicating the thickness mismatch.

[0010] In some embodiments, a substrate processing system is provided, the substrate processing system including: a substrate processing chamber; a substrate storage container; a robot configured to select a substrate from the substrate storage container and transfer the selected substrate into the substrate processing chamber; and a processor and a memory coupled to the processor. The memory can include a plurality of computer-readable instructions that, when executed by the processor, cause the system to: detect a lower edge and an upper edge of the substrate; calculate the thickness of the substrate based on the detected lower edge and the detected upper edge of the substrate; compare the calculated thickness of the substrate with the expected thickness of the substrate, and (i) if the calculated thickness matches the expected thickness, control the robot to transfer the substrate into the substrate processing chamber, and (ii) if the calculated thickness does not match the expected thickness, generate an alert indicating the thickness mismatch.

[0011] In some embodiments, a non-transitory computer-readable memory storing computer-readable instructions for operating a substrate processing system is provided. The substrate processing system includes a substrate processing chamber, a substrate storage container, and a robot configured to select a substrate from the substrate storage container and transfer the selected substrate into the substrate processing chamber. The system may further include a processor coupled to operate the substrate processing system. When executed by the processor, the computer-readable instructions may cause the processor to control the substrate processing system: detect a lower edge and an upper edge of the substrate; calculate a thickness of the substrate based on the detected lower edge and the detected upper edge of the substrate; compare the calculated thickness of the substrate with an expected thickness of the substrate, and (i) if the calculated thickness matches the expected thickness, control the robot to transfer the substrate into the substrate processing chamber, and (ii) if the calculated thickness does not match the expected thickness, generate an alert indicating a thickness mismatch.

[0012] Various implementations of the method, system, or computer-readable instructions may include one or more of the following features. Detecting the lower edge and the upper edge of the substrate may be accomplished during a substrate mapping process in which the number of substrates in the substrate storage container and the location of each substrate are mapped. The robot may include a robotic arm having sensors configured to detect the lower edge and the upper edge of the substrate. The robotic arm may include a first finger and a second finger spaced apart from each other in an opposed relationship. The sensors may include a laser and a photodetector. The laser may be positioned near a distal end of the first finger, and the photodetector may be positioned near a distal end of the second finger. The laser and the photodetector may be aligned with each other such that the photodetector can detect a laser beam emitted from the laser. Detecting the lower edge and the upper edge of the substrate may be accomplished when the robotic arm vertically scans across the substrate storage container and is positioned such that an outer perimeter of the substrate passes between the first finger and the second finger during the scanning process to interrupt the laser beam. The system may further include a controller operatively coupled to control functions of the substrate processing system and a computer-readable memory coupled to the controller. The substrate processing chamber may be used for defect review, classification, and analysis, and the chamber may include a focused ion beam (FIB) column and a scanning electron microscope (SEM) column. The substrate may be a semiconductor wafer.

[0013] Additional implementation manners may further include one or more of the following features. The method may further include inputting an expected substrate thickness into a computer-readable memory via a user interface before detecting the lower and upper edges of the substrate. The method may further include setting or adjusting one or more components of a substrate processing chamber based on the expected thickness of the substrate before detecting the lower and upper edges of the substrate. If the calculated thickness does not match the expected thickness, the method may further include preventing the substrate from being transferred into the substrate processing chamber. If the calculated thickness does not match the expected thickness, the method may further include setting or adjusting one or more components of the substrate processing chamber based on the calculated substrate thickness.

[0014] To better understand the nature and advantages of the present disclosure, reference should be made to the following description and drawings. However, it should be understood that each of the drawings is provided for illustrative purposes only and is not intended to define a limitation on the scope of the present disclosure. Moreover, as a general rule, and unless clearly contrary from the description, where elements in different drawings use the same element symbols, these elements are generally the same or at least similar in function or purpose. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1A is a simplified top view of a substrate that can be processed within a tool according to an embodiment disclosed herein;

[0016] Figure 1B is a simplified side view depicting different widths of three different substrates that can be processed within a tool according to an embodiment disclosed herein;

[0017] Figure 2 is a simplified diagram of a substrate processing system according to some embodiments;

[0018] Figure 3A is a simplified diagram of a substrate transfer mechanism and a substrate storage container according to some embodiments;

[0019] Figure 3B is according to some embodiments Figure 3A a simplified top view of a robotic arm of the substrate transfer mechanism shown;

[0020] Figure 4 is depicting according to some embodiments Figure 3A and Figure 3B a simplified top view of the positional relationship between the robotic arm and the perimeter of a sample with a measured thickness shown;

[0021] Figure 5 is a flowchart depicting steps associated with a method according to some embodiments;

[0022] Figures 6A to 6Dis a simplified schematic diagram depicting the positional relationship between a substrate transfer mechanism and a substrate during different steps of the method depicted in Figure 5 ; and

[0023] Figure 7 is a flowchart depicting steps associated with the method according to some embodiments;

[0024] Figure 8 is a simplified diagram of a sample evaluation system according to some embodiments of the present disclosure; and

[0025] Figure 9 is a simplified diagram of an area on a semiconductor wafer that can be transferred into a substrate processing chamber according to some embodiments.

[0026] DETAILED IMPLEMENTATION

[0027] As described above, some semiconductor manufacturers process substrates of different thicknesses in the same tool or set of tools in a manufacturing facility. For example, Figure 1A is a simplified top view of a substrate 100 that can be processed in a semiconductor or similar manufacturing facility. Substrate 100 can represent the substrate discussed below with respect to FIG. #, and as a non-limiting example, can be a silicon substrate, a gallium arsenide (GaAs) substrate, an indium phosphide (InP) substrate, or a sapphire substrate, among other substrates. Substrate 100 is generally circular and very thin relative to its diameter, and is thus sometimes referred to herein as a "wafer".

[0028] Figure 1B is a simplified side view depicting different substrates 100 each having the same general shape and diameter but different thicknesses from one another. For example, as depicted, substrate 100a is thinner than substrate 100b, and substrate 100b is thinner than substrate 100c. While embodiments of the present invention are not limited to processing substrates of any particular thickness, as a non-limiting example, in some embodiments, substrate 100a can have a thickness t of approximately 300 μm a , substrate 100b can have a thickness t of approximately 700 μm b , and substrate 100c can have a thickness t of approximately 1,400 μm c . While each of the different substrates 100a, 100b, and 100c can have the same overall shape and can be processed in the same tool in some operations, the different thicknesses of the substrates may require that the tool have one or more components that need to be set or adjusted differently depending on whether substrate 100a, 100b, or 100c (or a series of substrates 100a, 100b, or 100c) is transferred into the tool.

[0029] Embodiments of the present disclosure provide methods and systems for automatically detecting the thickness of substrates (such as substrates 100a, 100b, and 100c) before transferring the substrates to a substrate processing tool. Some embodiments can generate an alert or signal indicating that the actual thickness of the substrate about to be transferred to the tool does not match the expected thickness in the case where the sample is thicker or thinner than the thickness set for the tool to process. In some embodiments, the tool can respond to the signal, for example, prevent the sample from being transferred to the tool, or make one or more adjustments within the tool to set the tool to accept and process samples with the actually measured thickness. Although embodiments of the present disclosure can be used to detect the thickness of various different types of substrates or samples, some embodiments are particularly applicable to detecting the thickness of samples that are semiconductor wafers or similar specimens.

[0030] Exemplary substrate processing system

[0031] For a better understanding and full appreciation of the present disclosure, reference is now made to Figure 2 , which is a simplified schematic diagram of a substrate processing system 200 according to embodiments disclosed herein. As shown, the substrate processing system 200 may include a substrate processing tool 210, which can be used to process one or more substrates. The substrate processing tool can be any type of chamber, including but not limited to: a chemical vapor deposition unit, a physical vapor deposition unit, an etching unit, a chemical mechanical polishing unit, a lithography unit, or a metrology unit, and other units. In the depicted embodiment, the substrate processing tool 210 includes a vacuum chamber 212, a substrate support 214 configured to hold a substrate 216 (such as one of substrates 100a, 100b, or 100c) during substrate processing operations, and a chamber door 218 that enables substrates, including the substrate 216, to be transferred into and out of the vacuum chamber 212.

[0032] The substrate processing system 200 further includes a substrate transfer mechanism 220 (such as a robot) and a substrate storage container 230. The substrate transfer mechanism 220 can transfer substrates between the vacuum chamber 212 and the substrate storage container 230 through the chamber door 218. The substrate storage container can be an enclosed device designed to securely and safely hold substrates (such as wafers) in a controlled environment and allow the substrate transfer mechanism 220 to transfer substrates between different tools for processing or measurement. In some embodiments, the substrate storage container 230 can be a Front Opening Unified Pod (FOUP), which is designed according to a common protocol for transferring substrates between different tools in a manufacturing facility.

[0033] As Figure 2As depicted, the substrate processing system 200 may also include one or more controllers, processors, or other hardware units 240 that control the operation of the system 200 (including the processing tool 210 and the substrate transfer mechanism 220) by executing computer instructions stored in one or more computer-readable memories 250, which is known to those of ordinary skill in the art. For example, the 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 the like), disk drives, optical storage devices, or similar non-transitory computer-readable storage media.

[0034] Additionally, a user interface 260 may be provided to allow one or more users (e.g., personnel in a semiconductor manufacturing facility) to control various aspects of the substrate processing system 200, including identifying the thickness of the substrate transferred from the substrate storage container 230 into the substrate processing tool 210 so that various aspects of the substrate processing tool 210 can be set accordingly. The various components and / or aspects of the tool 210 that can be set or changed based on the thickness of the substrate processed within the chamber 212 depend on the type and design of the tool 210. For example, in a deposition or etching tool, the position of the substrate holder 214 (e.g., Z-direction height) and / or a preset distance between the gas distributor or manifold and the substrate holder may be set according to the substrate thickness. As another example, in a focused ion beam (FIB) tool, the position of the substrate holder 214 (e.g., Z-direction height) and / or a preset distance between the focused ion beam column tip may be set according to the substrate thickness.

[0035] In the past, once the thickness of the substrate within the substrate storage container 230 was identified, the system 200 could begin processing the substrate within the chamber 212. For example, the system 200 could transfer a first substrate from the storage container 230 to the chamber 212 via the transfer mechanism 220 and process the first substrate within the chamber 212. When the processing operation is complete, the transfer mechanism 220 can transfer the first substrate back to the storage container 230 and transfer a new, second substrate to the chamber 212 for processing. This sequence can then be repeated until all the substrates in the storage container 230 have been processed, at which point the storage container can be transferred to a different tool where the substrates in the container undergo the next processing operation.

[0036] Exemplary substrate transfer mechanism and substrate storage container

[0037] Figure 3A is a simplified diagram of a substrate transfer mechanism 300 and a substrate storage container 330 according to some embodiments. The substrate transfer mechanism 300 may represent the one described above with respect toFigure 2 The substrate transfer mechanism 220 discussed in [[ID=]], and the substrate storage container 330 may represent the substrate storage container 230. As shown, the substrate transfer mechanism 300 includes a robot base 310 and an arm 320 connected to the base 310, and the substrate storage container 330 can stably store a set of substrates 332 (e.g., 25 substrates in some embodiments) in a controlled environment.

[0038] Figure 3B is a simplified top view of the robot arm 320 according to some embodiments. The arm 320 may include two opposing fingers 322. The robot arm 320 also includes an arm sensor that can be positioned at the distal end of the fingers 322. In some embodiments, the arm sensor includes a pair of a transmitter 324 and a detector 326. The transmitter 324 can be a laser (e.g., an edge emitting laser (EEL) or a vertical cavity surface emitting laser (VCSEL)) positioned at the tip of one of the fingers 322, and the detector 326 can be a photodetector positioned at the tip of the opposing finger 322, with the detector 326 spaced apart and aligned with the transmitter 324 in an opposing relationship, allowing the detector 326 to detect the radiation 328 (e.g., a laser beam) emitted from the transmitter 324.

[0039] In operation, the robot arm 320 can extend outwardly into and enter the substrate storage container 330 to pick up a single substrate from the storage container and transfer the picked-up substrate to a substrate processing tool (e.g., to the substrate processing chamber 212). Then, after processing is completed, the arm 320 can pick up the substrate from the chamber 212 and transfer it back to the storage container 330.

[0040] In addition to extending outwardly into the substrate storage container 330, the arm 320 can further move up and down in the Z direction (represented by the arrow 340) to select any stacked substrate within the container 330. In normal operation, the substrate transfer mechanism 300 can use the signal from the detector 326 to correctly vertically position itself relative to the single substrate 332(i) to be transferred within the substrate stack 332. For example, the arm 320 can extend outwardly toward one of the substrates in the stack 332 such that the perimeter of the substrate is positioned within the gap between the two opposing fingers 324, as Figure 4 shown, but below (or above) the substrate 332(i). Then, the arm 320 can be raised (or lowered) relative to the substrate 332(i) until the substrate 332(i) interrupts the radiation ion beam 328, thereby indicating to the substrate transfer mechanism 300 the vertical position of the substrate 332(i).

[0041] Detecting substrate thickness

[0042] The embodiments disclosed herein can use the emitter / detector features of the substrate transfer mechanism 300 to measure the thickness of a single substrate and ensure that the substrates transferred into the processing chamber served by the substrate transfer mechanism 300 have the thickness that the processing chamber is set up to receive and process. For illustration, reference is made to Figure 5 and Figures 6A to 6D . Figure 5 is a flowchart depicting steps associated with method 500 according to some embodiments disclosed herein, and Figures 6A to 6D is a simplified schematic diagram depicting the positional relationship between the substrate transfer mechanism and the substrate during different steps of method 500. Figures 6A to 6D Each of Figures 6A to 6D depicts a front view and a top view of the substrate 610 to be loaded into the processing chamber side by side in each figure. For ease of illustration, Figures 6A to 6D only depicts the substrate 610 and portions of the substrate transfer mechanism, including the laser 622 and the photodetector 624, and the laser beam 626 emitted by the laser 622 can be detected by the photodetector 624 when the beam is not interrupted by a portion of, for example, the substrate 610. The laser 622 and the photodetector 624 can respectively represent the emitter 324 and the photodetector 326.

[0043] Method 500 can begin by moving a substrate storage container (e.g., container 230) to an appropriate position such that the substrates within the container, including substrate 610, can be loaded into a substrate processing system (e.g., system 200), and updating the substrate processing system with information indicating the thickness of the substrates stored in the substrate storage container and other information (block 510). The substrate thickness information can be input in any suitable manner. For example, in some embodiments, the information can be input by a user (e.g., a worker in a semiconductor manufacturing system) via the user interface 260. Next, one or more components of a processing tool (e.g., the substrate processing tool 210) can be set or adjusted to set up the tool to process substrates having an expected thickness (block 520), as described above. For example, in a deposition or etching tool, the position of the substrate holder 214 (e.g., the Z-direction height) and / or a preset distance between the gas distributor or manifold and the substrate holder can be set according to the substrate thickness. For example, in a focused ion beam (FIB) tool or a scanning electron microscope (SEM) tool, the position of the substrate holder 214 (e.g., the Z-direction height) and / or a preset distance between the focused ion beam column tip or the scanning electron microscope column tip can be set according to the substrate thickness.

[0044] Next, the substrate transfer mechanism 300 can initiate a mapping process (block 530), where the system will map and record (e.g., record in the memory 250) the number of substrates and the position of each substrate (e.g., the slot number in the FOUP) before any substrate is transferred into the substrate processing chamber. The mapping process can begin by slightly extending the robotic arm 320 into the substrate storage container such that the arm is positioned below the bottommost substrate while the perimeter of each substrate in the substrate stack is directly above the gap between two opposing fingers 324 (block 532), as Figure 4 described. As a non-limiting example, in some embodiments, the mapping process can be accomplished by positioning the robotic arm such that the laser beam 626 extends 6 mm beyond the substrate edge. During the mapping process, the laser 622 can project a laser beam 626 towards the photodetector 624 and scan the robotic arm upwards such that the laser beam passes through the outer perimeter of each individual substrate in the substrate storage container (block 534).

[0045] As the robotic arm scans upwards at a constant speed (block 534), the laser beam will be intermittently interrupted by each individual substrate in the container. To illustrate the process for a single substrate 610, reference Figures 6A to 6D is made. As Figure 6A shown, when the laser beam 626 is below the substrate 610, the beam is not interrupted by the substrate and is thus detected by the photodetector 624 (note that Figure 6A the right portion of Figure 6B shows the position where the laser beam 626 passes below the substrate 610 via a dashed line). As the robotic arm scans upwards, the laser beam 626 will contact the lower edge of the substrate 610 (as indicated by the asterisk in Figure 6C ). The interruption of the laser beam 626 prevents the photodetector 624 from detecting the laser beam and can be noted as the lower edge of the substrate 610 (and saved in the computer memory). As the robotic arm is further raised ( Figure 6C ), the interruption of the laser beam 626 continues until the robotic arm passes the upper edge of the substrate 610. At that point (as Figure 6D shown), the laser beam 626 is no longer interrupted by the substrate 610 and can be detected again by the light sensor 624. The re-detection of the laser beam 626 can then be noted as the upper edge of the substrate 610 (and saved in the computer memory) (block 536). In some embodiments, the edge detection process can be repeated for each substrate in the substrate storage container.

[0046] After detecting the lower and upper edges of the substrate 610, the thickness of the substrate 610 can be easily calculated (block 540). For example, in the case where the substrate transfer mechanism records the absolute or relative Z-height position of the robotic arm, the thickness of the substrate 610 can be determined by the difference between the Z-height positions recorded at the lower and upper substrate edges. As another example, if the detection of the lower and upper edges of the substrate 610 is stored in the memory as time units, the thickness of the substrate 610 can be calculated by multiplying the time difference between two detection events by the speed of the robotic arm in the Z direction.

[0047] Next, the substrate processing system can compare the substrate thickness calculated in block 540 with the input / expected substrate thickness in block 510 (block 550). If the two match, the substrate 610 can be transferred to the substrate processing chamber for any substrate processing operations to be performed in the equipment chamber (block 560). In some embodiments, to transfer the substrate, the robotic arm can immediately lower itself below the substrate, further extend into the substrate container, and then move slightly upward so that the substrate rests on the upper surface of the robotic arm, including the upper surface of the finger 322.

[0048] The match can be determined based on any suitable criteria. For example, in some embodiments, the match can be determined based on whether the calculated thickness is within a predetermined percentage of the expected thickness (e.g., within 5%, within 10%, or within 20%). As another example, in some embodiments, the thickness on sample substrates of different thicknesses can be calculated according to blocks 550 and 560, and the calculated measurements, which may be different from the actual thickness of the substrate, can subsequently be reconciled with the actual substrate thickness and stored in a look-up table or similar data structure. Then, when the thickness measurement of the substrate to be processed according to method 500 is calculated, the calculated thickness can be compared with the look-up table and associated with the expected thickness to determine the match. The look-up table can be referenced based on the ranges stored in the table, or an average or median value can be stored in the table, and the association can be based on the calculated thickness being within a predetermined percentage of the stored average or median value.

[0049] However, if the calculated substrate thickness does not match the input / expected substrate thickness, an "unmatched substrate thickness" alert can be generated (block 570), and appropriate corrective actions can be taken (block 580). The corrective actions can include any appropriate actions to fix the mismatch in substrate thickness. As a non-limiting example, such actions can include one or more of the following: sending an alert to a tool operator (e.g., a worker within a manufacturing facility) so that the operator can take corrective actions; automatically changing or otherwise altering the settings of the tool to adjust one or more chamber components such that the chamber is set up to process substrates having the calculated thickness rather than the initially expected thickness; preventing the substrate 610 from being transferred into the processing chamber and replacing its substrate storage container with a new substrate storage container that includes substrates having the expected thickness.

[0050] In some embodiments, once the appropriate corrective actions have been taken, the substrate is ready to be transferred into the processing chamber, as indicated by the dashed line from block 580 to block 560. As described above, method 500 can be implemented as part of an initial mapping process, where the system maps and records (e.g., records in memory 250) the number of substrates and the location of each substrate (e.g., the slot number in a FOUP) before any substrates are transferred into the substrate processing chamber. Such a mapping process can be performed whenever a new substrate storage container is delivered to the system. In other embodiments, method 500 can be implemented separately for each substrate in a given substrate storage container, either separate from or in place of the above-described mapping process.

[0051] Although method 500 includes an initial step of having a user input information regarding the expected substrate thickness into the substrate processing system, in some embodiments this preliminary step is unnecessary. For example, Figure 7 is a flowchart depicting steps associated with method 700 according to some embodiments. Method 700 includes many of the same steps as method 500, and for the sake of brevity, the description of these steps will not be repeated. However, method 700 differs from method 500 in that method 700 can be fully automated by the substrate processing system, and once the substrate thickness is calculated (block 540), the substrate processing chamber will be automatically adjusted to process substrates having the calculated thickness (block 710).

[0052] Exemplary sample evaluation system

[0053] Although the embodiments disclosed herein can be advantageously used in many different types of substrate processing chambers, one particular type of processing chamber that can be used for these embodiments is a substrate evaluation system, which can be used to mill and image semiconductor wafers, deposit various materials on substrates using a particle-enhanced deposition process, and other operations. Figure 8is a simplified schematic diagram of such a substrate evaluation system 800. The substrate processing system 800 can include a vacuum chamber 810, as well as a focused ion beam (FIB) column 820 and a scanning electron microscope (SEM) column 830. During a processing operation, a support element 840 can support a sample 850 (e.g., a semiconductor wafer) within the chamber 810 during the processing operation, where the sample 850 (sometimes referred to herein as an "object" or "specimen") is subjected to a charged particle beam from one of the FIB 820 or the SEM column 830, and the sample can be moved within the vacuum chamber 810 between the fields of the two columns 820 and 830 as required for processing.

[0054] During a processing operation, one or more gases can be delivered into the chamber 810 via a gas injection system 860 for certain operations. For simplicity of illustration, Figure 8 the gas injection system 860 in [description] is depicted as a nozzle, but it should be noted that the gas injection system 860 can include a gas reservoir, a gas source, valves, one or more inlets and one or more outlets, and other elements. In some embodiments, the gas injection system 860 can be configured to deliver gas to a local region of the sample 850 rather than to the entire upper surface of the sample, where the local region is exposed to the charged particle beam scanning pattern. For example, in some embodiments, the gas injection system 860 has a nozzle diameter measured in hundreds of μm (e.g., between 400 μm and 500 μm) and is configured to directly deliver gas to a relatively small portion of the sample surface that encompasses the charged particle beam scanning pattern. In various embodiments, a first gas injection system 860 can be configured to deliver gas to a sample positioned under the FIB column 820, while a second gas injection system 860 can be configured to deliver gas to a sample positioned under the SEM column 830.

[0055] The FIB column 820 and the SEM column 830 are connected to the vacuum chamber 810 such that the charged particle beam generated by either charged particle column can propagate through the vacuum environment formed within the chamber 810 before impinging on the sample 850. For example, as Figure 8 shown, the FIB column 820 can generate a focused ion beam 825 that travels through the vacuum environment of the chamber 810 and then impinges on the sample 850.

[0056] The FIB column 820 can mill (e.g., drill) the sample 850 by irradiating the sample with one or more charged particle beams to form a cross-section and can also smooth the cross-section. The cross-section can include one or more first portions of a first material and one or more second portions of a second material. The cross-section can also include additional portions of other materials. Conveniently, the smoothing operation involves using a smaller acceleration voltage relative to the sample milling. The SEM column 830 can generate an image of a portion of the sample 850 by irradiating the sample with a charged particle beam, detecting (e.g., using a suitable detector not shown in Figure 8 the particles emitted due to the irradiation, and generating a charged particle image based on the detected particles.

[0057] The particle imaging and milling processes generally each include scanning a charged particle beam back and forth (e.g., in a raster scan mode) at a constant rate over a specific region of the sample being imaged or milled. One or more lenses (not shown) coupled to the charged particle column can implement the scan mode as known to those skilled in the art. The scanned region is generally a very small portion of the overall region of the sample. For example, the sample can be a semiconductor wafer with a diameter of 200 or 300 mm, and each region scanned on the wafer can be a rectangular region with a width and / or length measured in micrometers or tens of micrometers.

[0058] As Figure 8 shown, the system 800 can include one or more controllers, processors, or other hardware units 870 that control the operation of the system 800 by executing computer instructions stored in one or more computer-readable memories 880, which is well known to those of ordinary skill in the art. For example, the computer-readable memory can include solid-state memory (such as random access memory (RAM) and / or read-only memory (ROM), which can be programmable, flash-updateable, and / or the like), disk drives, optical storage devices, or similar non-transitory computer-readable storage media.

[0059] Exemplary sample to be transferred

[0060] As previously mentioned, although embodiments of the present disclosure can be used to process many types of samples or substrates, some embodiments are particularly useful in measuring the thickness of wafers used to fabricate semiconductor devices, including silicon wafers, gallium arsenide wafers, etc. As a non-limiting example, Figure 9 is a simplified icon of an area on a semiconductor wafer that can be transferred to a substrate processing chamber (such as the chamber 800 discussed above). Specifically, Figure 9Includes a top view of wafer 900 and two expanded views of specific portions of wafer 900. Wafer 900 can be, for example, a 150 mm, 200 mm, or 300 mm semiconductor wafer and can include a plurality of integrated circuits 910 (fifty-two in the depicted example) formed thereon. The integrated circuits 910 can be in an intermediate stage of manufacture, and once substrate 900 is transferred into the chamber according to one of the above-described 500 or 700 methods, chamber 800 can be used to evaluate and analyze one or more regions 920 of the integrated circuit.

[0061] Other embodiments

[0062] This specification provides a thorough understanding of the described embodiments using specific terms for purposes of explanation. However, these specific details are not necessarily required for a person skilled in the art to practice the described embodiments. Thus, the foregoing description of the specific embodiments described herein is for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. For example, while methods 500 and 700 were discussed above as detecting the substrate edge when a robotic arm moves from a position below the substrate to above the substrate, in some embodiments, the detection process can be reversed, i.e., the robotic arm moves from above the substrate to below the substrate. Additionally, in other embodiments, other techniques (e.g., using a camera or other imaging device positioned a known distance from the substrate) can be used to detect the top and bottom edges of the substrate.

[0063] Meanwhile, while different embodiments of the present disclosure have been disclosed above, the specific details of a particular embodiment can be combined in any suitable manner without departing from the spirit and scope of the present disclosure. Further, many modifications and variations are possible for a person of ordinary skill in the art in light of the above teachings. Thus, it is to be understood that the appended claims are intended to cover all such modifications and variations that fall within the true spirit of the embodiments of the present disclosure.

[0064] Additionally, any reference to a method in the above specification should apply to a system capable of performing the method and should apply to a computer program product storing instructions that, when executed, cause the method to be performed. Similarly, any reference to a system in the above specification should apply to a method that can be performed by the system and should apply to a computer program product of instructions that can be executed by the system; any reference to a computer program product in the specification should apply to a method that can be performed when executing the instructions stored in the computer program product and should apply to a system configured to execute the instructions stored in the computer program product.

[0065] Moreover, while the illustrated embodiments of the present disclosure can be implemented in most cases using electronic components and circuits known to those skilled in the art, details of such content are not explained in greater depth than those described above in order to understand and appreciate the basic concepts of the present disclosure without obscuring or distracting from the teachings of the present disclosure.

Claims

1. A method of operating a substrate processing system, the system including a substrate processing chamber, a substrate storage container, and a robot configured to select a substrate from the substrate storage container and transfer the selected substrate into the substrate processing chamber, the method including: Detecting a lower edge and an upper edge of the substrate; Calculating a thickness of the substrate based on the detected lower edge and the detected upper edge of the substrate; Comparing the calculated thickness of the substrate with an expected thickness of the substrate; And (i) If the calculated thickness matches the expected thickness, controlling the robot to transfer the substrate into the substrate processing chamber; (ii) If the calculated thickness does not match the expected thickness, generating an alarm indicating a thickness mismatch.

2. The method of operating a substrate processing system according to claim 1, wherein detecting the lower edge and the upper edge of the substrate is completed during a substrate mapping process in which the number of substrates in the substrate storage container and the position of each substrate are mapped and recorded.

3. The method of operating a substrate processing system according to claim 2, wherein the substrate storage container is a front-opening unified pod (FOUP).

4. The method of operating a substrate processing system according to claim 1, wherein the robot includes a robot arm having sensors configured to detect the lower edge and the upper edge of the substrate.

5. The method of operating a substrate processing system according to claim 4, wherein the robot arm includes a first finger and a second finger spaced apart from each other in an opposing relationship, and the sensors include a laser and a photodetector, the laser being positioned near a distal end of the first finger, and the photodetector being positioned near a distal end of the second finger and aligned with the laser such that the photodetector can detect a laser beam emitted from the laser.

6. The method of operating a substrate processing system according to claim 5, wherein detecting the lower edge and the upper edge of the substrate is completed when the robot arm vertically scans across the substrate storage container and is positioned such that an outer periphery of the substrate passes between the first finger and the second finger during the scanning process, thereby interrupting the laser beam.

7. The method of operating a substrate processing system according to claim 1, wherein the system further includes a controller operatively coupled to control functions of the substrate processing system and a computer-readable memory coupled to the controller, and wherein the method further includes inputting the expected substrate thickness into the computer-readable memory via a user interface before detecting the lower edge and the upper edge of the substrate.

8. The method of operating a substrate processing system according to any one of claims 1 to 7, the method further including, before detecting the lower edge and the upper edge of the substrate, setting or adjusting one or more components of the substrate processing chamber based on the expected thickness of the substrate.

9. The method of operating a substrate processing system as claimed in claim 8, wherein if the calculated thickness does not match the expected thickness, the transfer of the substrate into the substrate processing chamber is prevented.

10. The method of operating a substrate processing system as claimed in claim 8, wherein if the calculated thickness does not match the expected thickness, one or more components of the substrate processing chamber are set or adjusted based on the calculated substrate thickness.

11. The method of operating a substrate processing system as claimed in claim 1, wherein the substrate processing chamber is capable of being used for defect review, classification, and analysis, and the chamber includes a focused ion beam (FIB) column and a scanning electron microscope (SEM) column.

12. The method of operating a substrate processing system as claimed in claim 1, wherein the substrate is a semiconductor wafer.

13. A substrate processing system, the substrate processing system comprising: a substrate processing chamber; a substrate storage container; a robot configured to select a substrate from the substrate storage container and transfer the selected substrate into the substrate processing chamber; and a processor and a memory coupled to the processor, the memory including a plurality of computer-readable instructions which, when executed by the processor, cause the system to: detect a lower edge and an upper edge of the substrate; calculate the thickness of the substrate based on the detected lower edge and the detected upper edge of the substrate; compare the calculated thickness of the substrate with an expected thickness of the substrate, and: (i) if the calculated thickness matches the expected thickness, control the robot to transfer the substrate into the substrate processing chamber, (ii) if the calculated thickness does not match the expected thickness, generate an alert indicating a thickness mismatch.

14. The substrate processing system as claimed in claim 13, wherein the detection of the lower edge and the upper edge of the substrate is completed during a substrate mapping process in which the number of substrates in the substrate storage container and the position of each substrate are mapped and recorded.

15. The substrate processing system according to claim 13 or 14, wherein the robot comprises: A robot arm having a first finger and a second finger spaced apart from each other in an opposed relationship, and a sensor including: a laser positioned near a distal end of the first finger; and a photodetector positioned near a distal end of the second finger and aligned with the laser such that the photodetector is capable of detecting a laser beam emitted from the laser.

16. The substrate processing system as claimed in claim 15, wherein the lower edge and the upper edge of the substrate are detected when the robot arm vertically scans across the substrate storage container and is positioned such that an outer periphery of the substrate passes between the first finger and the second finger during the scanning process to interrupt the laser beam.

17. A non - transitory computer - readable memory storing computer - readable instructions for operating a substrate processing system, the substrate processing system including a substrate processing chamber, a substrate storage container, and a robot configured to select a substrate from the substrate storage container and transfer the selected substrate into the substrate processing chamber, wherein when executed by a processor operatively coupled to the substrate processing system, the computer - readable instructions cause the processor to control the substrate processing system: Detect a lower edge and an upper edge of the substrate; Calculate a thickness of the substrate based on the detected lower edge and the detected upper edge of the substrate; Compare the calculated thickness of the substrate with an expected thickness of the substrate, and (i) if the calculated thickness matches the expected thickness, control the robot to transfer the substrate into the substrate processing chamber, and (ii) if the calculated thickness does not match the expected thickness, generate an alarm indicating a thickness mismatch.

18. The non - transitory readable computer memory of claim 17, wherein detecting the lower edge and the upper edge of the substrate is completed during a substrate mapping process in which the number of substrates in the substrate storage container and the position of each substrate are mapped and recorded.

19. The non-transitory computer-readable memory according to claim 17 or 18, wherein the robot includes a robotic arm having a first finger and a second finger spaced apart from each other in an opposing relationship, and a sensor, the sensor including: A laser positioned near a distal end of the first finger; And a photodetector positioned near a distal end of the second finger and aligned with the laser such that the photodetector can detect a laser beam emitted from the laser.

20. The non - transitory computer - readable memory of claim 19, wherein the lower edge and the upper edge of the substrate are detected when the robot arm vertically scans across the substrate storage container and is positioned such that an outer perimeter of the substrate passes between the first finger and the second finger during the scanning process, thereby interrupting the laser beam.

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