Integrated Adaptive Positioning System and Routine for Automated Wafer Handling Robot Teaching and Health Inspection

Abstract

Systems and techniques for determining and using various types of offsets of a wafer support of a wafer station for providing wafers to a semiconductor processing tool are disclosed; such techniques and systems may use an auto-calibration wafer that may have multiple sensors, including multiple edge-mounted camera sensors that may be used to image fiducials associated with two different structures located at a selected wafer station.

Description

[0001] Incorporation by reference

[0002] The PCT application form is filed simultaneously with this specification as part of this application. Each application for which this application claims the benefit or priority, as identified in the PCT application form filed simultaneously, is incorporated herein by reference in its entirety and for all purposes. BACKGROUND OF THE INVENTION

[0003] Semiconductor processing tools use wafer handling robots to move semiconductor wafers between various wafer stations. Since wafer handling robots typically pick up semiconductor wafers using end effectors of a handle type or a spoon type and the semiconductor wafers are not reliably fixed to the end effectors of the wafer handling robots, there is usually a small variation in the relative placement between the end effector and the semiconductor wafer placed thereon. Due to the sensitivity of semiconductor processing operations, such variations generated when placing semiconductor wafers using a wafer handling robot are typically corrected to place the semiconductor wafers at desired positions in their respective processing stations, such as substantially centered in the processing stations, within an acceptable tolerance range. Modern semiconductor processing tools use an Active Wafer Centering (AWC) system to assist such wafer placement. SUMMARY OF THE INVENTION

[0004] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. The following non-limiting implementations should be considered as part of the present disclosure; other implementations will be apparent from the present disclosure and the entireties of the accompanying drawings.

[0005] In some implementations, a system for assisting in the calibration of a wafer handling robot of a semiconductor processing tool may be provided. The system may include, for example, an auto-calibration wafer that includes: a substrate sized to be transported by the wafer handling robot and having a first side configured to contact the end effector of the wafer handling robot when the substrate is transported by the wafer handling robot; a plurality of first camera sensors supported by the substrate and positioned at a plurality of positions offset from a common point of the substrate, each first camera sensor having a downward-facing field of view when the substrate is positioned with the first side facing down; and a first controller communicatively coupled to each of the first camera sensors.

[0006] In some implementations of the system, the first camera sensors may be arranged in a circular array around the common point.

[0007] In some implementations of the system, the substrate can be nominally circular and can have the same diameter as the semiconductor wafer configured to be processed by the semiconductor processing tool.

[0008] In some implementations of the system, the substrate can be nominally circular and can have the same diameter as the edge ring configured to be used by the semiconductor processing tool.

[0009] In some implementations of the system, the substrate can be nominally circular and can have a diameter between the outer diameter and the inner diameter of the edge ring configured to be used by the semiconductor processing tool.

[0010] In some implementations of the system, the substrate can be nominally circular and can have a diameter that is within ±10% of the average between the outer diameter and the inner diameter of the edge ring, and the semiconductor processing tool is configured to use the edge ring.

[0011] In some implementations of the system, the substrate can be a nominally circular disk, and the disk can have a diameter selected from the group consisting of 200 mm, 300 mm, and 450 mm.

[0012] In some implementations of the system, the auto-calibration wafer can further include a power source configured to supply power to at least the first controller and the first camera sensor.

[0013] In some implementations of the system, the power source can be a rechargeable battery, and the auto-calibration wafer can further include a wireless charging feature configured to charge the rechargeable battery when the rechargeable battery docks with an electromagnetic field.

[0014] In some implementations of the system, the auto-calibration wafer can further include a first wireless communication interface, and the first wireless communication interface is communicatively connected to the first controller.

[0015] In some implementations of the system, the first wireless communication interface can include one or more wireless communication interfaces, such as a Bluetooth transceiver or a WiFi transceiver.

[0016] In some implementations of the system, the auto-calibration wafer can further include one or more orientation sensors, and the one or more orientation sensors can be communicatively connected to the first controller.

[0017] In some implementations of the system, each of the orientation sensors can be an inclinometer or an accelerometer.

[0018] In some implementations of the system, the automatic calibration wafer may further include one or more vibration sensors, and the one or more vibration sensors may be communicatively coupled to the first controller.

[0019] In some implementations of the system, each vibration sensor may be an accelerometer, a laser microphone, or an optical distance measurement sensor.

[0020] In some implementations of the system, the automatic calibration wafer may further include one or more proximity sensors, each proximity sensor being configured to measure the distance between the first side and an object located below the proximity sensor when the first side faces downwards, and the one or more proximity sensors may be communicatively coupled to the first controller.

[0021] In some implementations of the system, each proximity sensor may be an optical proximity sensor, an inductive proximity sensor, or a capacitive proximity sensor.

[0022] In some implementations of the system, the first camera sensor may be arranged in a circular array around the common point, the substrate may be nominally circular and may have the same diameter as the semiconductor wafer configured to be processed by the semiconductor processing tool, the substrate may be a nominally circular disc, and the disc has a diameter selected from the group consisting of 200 mm, 300 mm, and 450 mm, and the automatic calibration wafer may further include: a rechargeable battery configured to supply power to at least the first controller and the first camera sensor; a wireless charging feature configured to charge the rechargeable battery when the rechargeable battery is docked with an electromagnetic field; a first wireless communication interface that may be communicatively coupled to the first controller and may include one or more wireless communication interfaces such as a Bluetooth transceiver or a WiFi transceiver; one or more vibration sensors that may be communicatively coupled to the first controller; and one or more proximity sensors, each proximity sensor being communicatively coupled to the first controller and being configured to measure the distance between the first side and an object located below the proximity sensor when the first side faces downwards.

[0023] In some implementations of the system, the system may further include the semiconductor processing tool, and the semiconductor processing tool may include: a wafer transfer robot; one or more wafer stations; and a second controller. In such an implementation, each wafer station may include one or more corresponding wafer supports, the wafer transfer robot may be communicatively coupled to the second controller, and the second controller and the first controller are jointly configured to: a) select a first wafer support among the one or more wafer supports of a first wafer station among the one or more wafer stations; b) cause the wafer transfer robot to position the auto-calibration wafer above the first wafer station; and c) cause each first camera sensor to obtain a corresponding first image of the reference of the first wafer support when the auto-calibration wafer is positioned above the first wafer support.

[0024] In some implementations of the system, the second controller and the first controller may also be jointly configured to determine position information of the center point of the first wafer support based on the first image.

[0025] In some such implementations of the system, the second controller and the first controller may also be jointly configured to: d) cause the wafer transfer robot to retrieve the calibration wafer; and e) cause the wafer transfer robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer is nominally centered on the center point of the first wafer support when viewed along the vertical axis.

[0026] In some implementations of the system, the second controller and the first controller may also be jointly configured to: f) cause the wafer transfer robot to position the auto-calibration wafer above the first wafer support and the calibration wafer; g) cause each first camera sensor to obtain a corresponding second image of the reference of the first wafer support and the reference of the calibration wafer when the auto-calibration wafer is positioned above the first wafer support and the calibration wafer; and h) determine a horizontal offset of the wafer / wafer support between the center point of the calibration wafer and the center point of the first wafer support based on a gap size between the reference of the first wafer support and the reference of the calibration wafer in the second image.

[0027] In some implementations of the system, the second controller and the first controller may also be jointly configured to: i) compare the horizontal offset of the wafer / wafer support with a horizontal offset threshold of the wafer / wafer support; and j) in response to determining that the horizontal offset of the wafer / wafer support is higher than the horizontal offset threshold of the wafer / wafer support, cause the wafer handling robot to reposition the calibration wafer relative to the first wafer support to reduce the horizontal offset of the wafer / wafer support.

[0028] In some implementations of the system, the second controller and the first controller may also be jointly configured to repeat (f) through (j) N times or until the horizontal offset of the wafer / wafer support is at or below the horizontal offset threshold of the wafer / wafer support, whichever occurs first.

[0029] In some implementations of the system, the second controller and the first controller may also be jointly configured to: d) cause the wafer handling robot to retrieve a first edge ring; and e) cause the wafer handling robot to transfer the first edge ring to the first wafer support such that the center point of the first edge ring is nominally centered on the center point of the first wafer support when viewed along the vertical axis.

[0030] In some implementations of the system, the second controller and the first controller may also be jointly configured to: f) cause the wafer handling robot to place the auto-calibration wafer above the first wafer support and the first edge ring; g) cause each first camera sensor to obtain a corresponding second image of the reference of the first wafer support and the reference of the first edge ring when the auto-calibration wafer is placed above the first wafer support and the first edge ring; and h) determine a horizontal offset of the edge ring / wafer support between the center point of the first edge ring and the center point of the first wafer support based on a gap size between the reference of the first wafer support and the reference of the first edge ring in the second image.

[0031] In some implementations of the system, the second controller and the first controller may also be jointly configured to: i) compare the horizontal offset of the edge ring / wafer support with a horizontal offset threshold of the edge ring / wafer support; and j) in response to determining that the horizontal offset of the edge ring / wafer support exceeds the horizontal offset threshold of the edge ring / wafer support, cause the wafer handling robot to reposition the first edge ring relative to the first wafer support to reduce the horizontal offset of the edge ring / wafer support.

[0032] In some implementations of the system, the second controller and the first controller may also be jointly configured to repeat (f) through (j) N times or until the horizontal offset of the edge ring / wafersupport is at or below the horizontal offset threshold of the edge ring / wafersupport, whichever occurs first.

[0033] In some implementations of the system, the second controller and the first controller may also be jointly configured to: f) cause the wafer handling robot to retrieve a calibration wafer; and g) cause the wafer handling robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer is nominally centered on the center point of the first edge ring when viewed along the vertical axis.

[0034] In some implementations of the system, the second controller and the first controller may also be jointly configured to: h) cause the wafer handling robot to position the auto - calibration wafer above the first wafer support, the first edge ring, and the calibration wafer; i) cause each first camera sensor to obtain a corresponding second image of the reference of the calibration wafer and the reference of the first edge ring when the auto - calibration wafer is positioned above the first wafer support, the calibration wafer, and the first edge ring; and j) determine the horizontal offset of the edge ring / wafer between the center point of the first edge ring and the center point of the calibration wafer based on the gap size between the reference of the calibration wafer and the reference of the first edge ring in the second image.

[0035] In some implementations of the system, the second controller and the first controller may also be jointly configured to: k) compare the horizontal offset of the edge ring / wafer with the horizontal offset threshold of the edge ring / wafer; and l) in response to determining that the horizontal offset of the edge ring / wafer is higher than the horizontal offset threshold of the edge ring / wafer, cause the wafer handling robot to re - position the calibration wafer relative to the first edge ring to reduce the horizontal offset of the edge ring / wafer.

[0036] In some implementations of the system, the second controller and the first controller may also be jointly configured to repeat (h) through (l) M times or until the horizontal offset of the edge ring / wafer is at or below the horizontal offset threshold of the edge ring / wafer, whichever occurs first.

[0037] In some implementations of the system, the second controller and the first controller may also be jointly configured to: cause the wafer handling robot to reposition the auto-calibration wafer above the first wafer support, the first edge ring, and the calibration wafer; cause each first camera sensor to obtain a corresponding third image of the reference of the calibration wafer and the reference of the first wafer support when the auto-calibration wafer is positioned above the first wafer support, the calibration wafer, and the first edge ring; and determine a horizontal offset of the wafer support / wafer between the center point of the calibration wafer and the center point of the first wafer support based on a gap size between the reference of the first wafer support and the reference of the calibration wafer in the third image.

[0038] In some implementations of the system, the second controller and the first controller may also be jointly configured to: compare the horizontal offset of the wafer support / wafer with a horizontal offset threshold of the wafer support / wafer; and in response to determining that the horizontal offset of the wafer support / wafer is higher than the horizontal offset threshold of the wafer support / wafer, cause the wafer handling robot to reposition at least one object relative to the first wafer support, the at least one object being selected from the group consisting of the calibration wafer and the edge ring.

[0039] In some implementations of the system, the semiconductor processing tool may include a semiconductor processing chamber, the first wafer station may be located in the semiconductor processing chamber, and the first wafer support may include a pedestal in the semiconductor processing chamber.

[0040] In some implementations of the system, the semiconductor processing tool may include a load lock for transferring wafers between different pressure environments, the first wafer station is located in the load lock, and the first wafer support is a structure in the load lock.

[0041] In some implementations of the system, the semiconductor processing tool may include a buffer for storing one or more wafers before, after, or between processing operations, the first wafer station may be located in the buffer, and the first wafer support may be one of a plurality of wafer support frames in the buffer.

[0042] In some implementations of the system, the semiconductor processing tool may include a load lock for transferring wafers between different pressure environments, the first wafer station may be located in the load lock, and the first wafer support may be a structure in the load lock.

[0043] In some implementations of the system, the system may further include the semiconductor processing tool, where the semiconductor processing tool may include: a wafer transfer robot; one or more wafer stations; and a second controller. In such a system, each wafer station may include one or more corresponding wafer supports, the wafer transfer robot and the second controller are communicatively connected, and the second controller and the first controller may be jointly configured to: a) select a first wafer support among the one or more wafer supports of a first wafer station among the one or more wafer stations; b) cause the wafer transfer robot to transfer the auto-calibration wafer to the first wafer station; and c) cause the one or more orientation sensors to obtain an inclination measurement of the substrate.

[0044] In some implementations of the system, the second controller may be configured to remove the edge ring from the first wafer support before performing (b).

[0045] In some implementations of the system, the system may further include the semiconductor processing tool, the semiconductor processing tool may include: a wafer transfer robot; one or more wafer stations; and a second controller. In such an implementation, each wafer station may include one or more corresponding wafer supports, the wafer transfer robot and the second controller are communicatively connected, and the second controller and the first controller may also be jointly configured to: a) select a first wafer support among the one or more wafer supports of a first wafer station among the one or more wafer stations; b) cause a relative displacement between a plurality of lift pins of the first wafer support and the first wafer support so that the lift pins protrude from the first wafer support; c) cause the wafer transfer robot to transfer the auto-calibration wafer to the lift pins; d) when the auto-calibration wafer is supported by the lift pins, cause a further relative displacement between the lift pins and the first wafer support; e) obtain vibration data from the one or more vibration sensors during (d); f) evaluate the vibration data to determine whether the vibration data indicates that the vibration exceeds a predetermined threshold; and g) provide a notification when the vibration data exceeds the predetermined threshold.

[0046] In some implementations of the system, as part of (d), the second controller may be configured to: cause a further relative displacement between the lift pins and the first wafer support so that the lift pins no longer protrude from the first wafer support and the auto-calibration wafer rests on the upper surface of the first wafer support.

[0047] In some implementations of the system, the system can include the semiconductor processing tool, and the semiconductor processing tool can include: a wafer transfer robot; one or more wafer stations; and a second controller. In such a system, the wafer transfer robot and the second controller can be communicatively connected, and the second controller and the first controller can also be jointly configured to: a) select a first wafer support among the one or more wafer supports of a first wafer station of the one or more wafer stations, at least partially based on an indication that the edge ring is supported by the first wafer support; b) place the auto-calibration wafer onto the edge ring; c) cause each proximity sensor to measure the distance between the first wafer support and the auto-calibration wafer; d) determine one or more height measurements associated with the edge ring based on the one or more distances; e) evaluate the one or more height measurements to determine whether the height associated with the edge ring exceeds a predetermined threshold; and f) provide a notification when the height associated with the edge ring exceeds the predetermined threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Various implementations disclosed herein are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals refer to like elements.

[0049] Figure 1 An example of a calibration wafer placed relative to an edge ring is shown.

[0050] Figure 2 A schematic diagram of an exemplary auto-calibration wafer is shown.

[0051] Figure 3 A wafer support having lift pins is shown.

[0052] Figure 4 A side view of an auto-calibration wafer having a set of proximity sensors that can be used to determine edge ring height is shown.

[0053] Figure 5 A side view of another auto-calibration wafer having two sets of proximity sensors, each set of proximity sensors being arranged along a circular path of a different diameter, is shown.

[0054] Figure 6 A photograph of an exemplary auto-calibration wafer.

[0055] Figure 7 A plan view of another exemplary auto-calibration wafer.

[0056] Figures 8a to 8i A schematic diagram of a semiconductor processing tool during various operational phases is shown.

[0057] Figure 9Shows a flowchart of a technique for determining the position of a reference point of a structure at a wafer stage using an auto-calibration wafer.

[0058] Figure 10 Shows a flowchart of a technique for determining the relative positions of two structures at a wafer stage using an auto-calibration wafer.

[0059] Figure 11 Shows a flowchart of a technique for determining the position of the center point of a wafer support using an auto-calibration wafer.

[0060] Figure 12 Shows a flowchart of a technique for correcting the placement of an edge ring on a wafer support.

[0061] Figure 13 Shows a flowchart of a technique for correcting the placement of a wafer relative to an edge ring on a wafer support.

[0062] Figure 14 Shows a flowchart of a technique for verifying the repeatability of wafer placement.

[0063] Figure 15 Shows a flowchart of a technique for evaluating the height of an edge ring.

[0064] Figure 16 Shows a flowchart of a technique for evaluating lift pin vibration.

[0065] Figure 17 Shows a flowchart of a technique for evaluating chuck levelness.

[0066] The figures in this document are generally not drawn to scale, but the various aspects discussed below in the figures may be drawn to scale. Detailed Description

[0067] In a typical semiconductor processing system, accurately placing a wafer during the preparation for various semiconductor processing operations and / or wafer handling operations is achieved via a manual or semi-automatic teaching process, which typically requires the involvement of a technician or other person to supervise in order to: (1) "teach" the wafer handling robot the desired positions of the semiconductor wafer, edge ring, and / or wafer support such as an electrostatic chuck (ESC) relative to each other or relative to the end effector of the wafer handling robot; (2) "teach" the active wafer centering (AWC) system; and (3) perform verification of wafer placement repeatability; once the wafer handling robot has been taught such positions, for any given wafer, any potential deviation of the wafer placement from such positions due to, for example, a slight misalignment of the wafer with the end effector during wafer transfer to the end effector can be corrected via the use of AWC. Such a manual or semi-automatic teaching process is time-consuming and difficult to implement.

[0068] Such teaching processes typically begin by teaching the wafer handling robot the various positions where it will pick up or place wafers during semiconductor processing tool operation. Generally, while the wafer handling robot may initially be configured to have a general sense of each such position in the equipment, the wafer handling robot will need some degree of customization to adapt its operation to the specific characteristics of the particular semiconductor processing tool in which it is installed, such as adapting to different component tolerances or part tolerances. To achieve this, the wafer handling robot can be placed in a teaching mode, in which for each position to be "taught", the wafer handling robot can be guided to the position corresponding to that position, or into a configuration that places the wafer handling robot into certain "ideal" conditions for that position - for example, when the center of the semiconductor wafer is within a known distance (generally expected to be minimized or reduced to zero) from a reference point on the end effector of the wafer handling robot, and also within a known distance (generally expected to be minimized or reduced to zero) from the center of the wafer support at that position, the position or configuration in which the wafer handling robot is located.

[0069] In typical wafer handling robot training, for example via the use of one or more fixtures or other structures, the "ideal" positioning of the wafer handling robot for each position can be achieved, and the other structures can dock with features on the end effector of the wafer handling robot that can serve as reference points and another feature fixed relative to that target position. For example, in some wafer handling robot teaching scenarios, a disc-shaped fixture having a diameter similar to that of a semiconductor wafer can be placed on the end effector of the wafer handling robot using, for example, a rod axis or pin passing through the center of the disc and through a reference feature (such as a hole) in the end effector, and the disc-shaped fixture is centered at the position expected to be on the end effector, where the semiconductor wafer will be centered when the semiconductor wafer is transported by the wafer handling robot using the end effector. There may be similar pins installed in the features of the wafer support, and when the end effector / disc is urged against such pins, such pins can contact the edge of the disc, thereby guiding the disc and the end effector to a specific position, such as a centered position. During the movement of such a wafer handling robot, the wafer handling robot can be placed in an unpowered state to enable the operator to easily move the joint / arm section of the wafer handling robot via manual manipulation. Once the wafer handling robot is properly positioned, the controller of the wafer handling robot can obtain measurements of the various connection positions of the wafer handling robot by, for example, obtaining measurements of the relative or absolute angular displacements of the various rotating joints of the wafer handling robot, to determine what relevant motion states of the wafer handling robot are at the desired position at what times. Once the wafer handling robot obtains such position information and the position associated therewith, that position can be considered to have been taught to the wafer handling robot.

[0070] Once the wafer handling robot has been taught various positions where it will transfer (or retrieve) wafers, when performing future wafer transfer operations involving those positions, the wafer handling robot can be controlled to enter the motion state in which it was taught that position. If a semiconductor wafer placed on the end effector of the wafer handling robot is placed exactly centered on the reference point of the end effector, then after the wafer handling robot returns to the motion state in which it was taught that position, when the end effector of the wafer handling robot places the same semiconductor wafer, the semiconductor wafer will similarly be properly centered in the destination position. However, due to various factors, the semiconductor wafer placed on the end effector of the wafer handling robot may not be exactly centered on the reference point of the end effector. Such misalignment may be relatively minor, e.g., on the order of tens of microns, but such minor misalignment can be detrimental to wafer processing operations. Using an Active Wafer Centering (AWC) system to correct such end effector / wafer misalignment has become common in the industry.

[0071] In a typical AWC configuration, an optical AWC sensor and a beam emitter are positioned at fixed locations outside the semiconductor wafer processing chamber such that when the wafer handling robot transports a semiconductor wafer through the processing chamber, the semiconductor wafer moves through two or more of the multiple beams emitted by the beam emitter. The AWC sensor can detect when each beam encounters the edge of the semiconductor wafer (as evidenced by the blocking or reformation of the beam towards one of the multiple optical sensors). The AWC system can obtain the defined coordinate position of a reference point (e.g., a point nominally centered on the semiconductor wafer) on the end effector of the wafer handling robot from the sensors of the wafer handling robot in each instance where the edge of the semiconductor wafer triggers one of the AWC optical sensors (since the exact placement of the semiconductor wafer on the end effector may be unknown, this defined coordinate position is only an estimated or desired center position). For a circular semiconductor wafer and at least two AWC beam sensors, the four or more coordinates obtained (as few as three coordinates can be used) are sufficient to determine the position of the center point of the semiconductor wafer relative to the semiconductor processing chamber (both the AWC sensors and the wafer handling robot base are fixedly mounted relative to the semiconductor processing chamber). Once such center information of the wafer is obtained, it can be used as a reference position for future wafer placement, or it can be used as a measurement of the current wafer position that may need correction.

[0072] For example, to train the AWC system, a certain reference wafer can be manually centered on a desired destination (such as a pedestal) in a semiconductor processing chamber. Such manual centering can be performed, for example, with the assistance of a fixture or jig that can guide the reference wafer to be properly centered relative to the pedestal. Once the reference wafer is considered to be sufficiently centered on the pedestal, the wafer handling robot can be controlled to retrieve the reference wafer and remove the reference wafer from the semiconductor processing chamber; when removing the reference wafer from the semiconductor processing chamber, the AWC system can be used to measure and determine the center of the reference wafer. This information, along with information from the wafer handling robot describing the positions the reference wafer has experienced as it moves from the centered position on the pedestal to the center position determined by the AWC system, can be used to adjust future wafer placements to achieve similar wafer-pedestal centering. For example, if a new wafer is placed onto the wafer handling robot and passed through the AWC sensor in a manner similar to the reference wafer, an offset may be found between the center of the new wafer and the previously determined center position of the reference wafer, such as an offset of 0.5 mm in the X direction and 0.25 mm in the Y direction. To correct for such variations, the wafer handling robot can be controlled to apply a corrective displacement when placing the new wafer, such as moving the new wafer an additional -0.5 mm along the X direction and an additional -0.25 mm along the Y direction (opposite the displacement used to retrieve the reference wafer from the pedestal and move the reference wafer towards and through the AWC sensor) before, after, or during the displacement of the new wafer, to counteract such displacements when placing the new wafer on the pedestal.

[0073] Similar techniques using an AWC system can also be used to adjust the placement of the edge ring onto the wafer support. For example, when the edge ring passes through the light beam of the AWC system, the AWC can be used to determine the center point of the edge ring, as well as any offset between such an edge ring center point and a reference position used by, for example, the AWC system (serving as the "ideal" center placement position for the wafer or edge ring). In implementations where the AWC system is used in combination with edge ring placement, since the edge ring has an inner edge and an outer edge, the edge ring has more edge / beam intersections than a semiconductor wafer (thus, each optical sensor detects four edge / beam intersections when the edge ring passes through the AWC optical sensor, as opposed to the two intersections detected when a semiconductor wafer passes through the beam sensor). In such implementations, data obtained from some of the edge / beam intersections (e.g., intersections of the beam with the outer edge of the edge ring) can be ignored, and the center of the edge ring can be determined based on the remaining edge / beam intersections (e.g., intersections of the beam with the inner edge of the edge ring). In some implementations, the reference point used by the AWC system to evaluate the degree to which the edge ring deviates from the desired placement position on the end effector of the wafer handling manipulator can be the same reference point that can be used for AWC correction of the semiconductor wafer, i.e., the reference point determined based on measurements obtained from the semiconductor wafer using the AWC system. In other implementations, the reference point for AWC correction of the edge ring can be obtained based on measurements obtained from the edge ring using the AWC system. For example, the AWC system can be trained with the edge ring to obtain a reference point for future edge ring placement. It should be understood that the placement techniques discussed herein and the AWC training and correction techniques discussed herein can generally be applied in the context of both semiconductor wafer placement operations and edge ring placement operations.

[0074] AWC systems are widely used in the semiconductor processing industry and typically provide good wafer centering performance. However, training processes are extremely labor-intensive, time-consuming, and prone to user error. While such training can be performed as part of an initial semiconductor processing tool setup, it may need to be repeated periodically during the life of the tool, for example, when any modifications occur to the relative positions between the semiconductor processing chamber, the AWC sensors, and the wafer handling robot, or if the wafer processing operation starts to exhibit non-uniformities that imply that the placement of the semiconductor wafer on the pedestal has deviated from center, or generally if any maintenance (including wet cleaning) is performed on the processing chamber. It should be understood that in various implementations, the mention of placing a wafer or edge ring onto a wafer support, pedestal, or other facility by a wafer handling robot implicitly includes indirectly placing the wafer or edge ring onto the wafer support. For example, in many semiconductor processing tools, a vertically moving lift pin positioned within the wafer support can lift the wafer off the end effector of the wafer handling robot, and then the end effector can move away from beneath the wafer without moving the wafer. The lift pin can then be controlled to lower the wafer onto the wafer support. The same process can be repeated in reverse to remove the wafer or other structure from the wafer support. The term "wafer support" as used herein can refer to any of a variety of structures (excluding the end effector of the wafer handling robot) that can be used to support a semiconductor wafer within a semiconductor processing tool. The wafer support can include, for example, a pedestal, an ESC, or other generally circular pedestal-like structures that can be located within a semiconductor processing chamber (or other chamber) and that generally contact (such as via face-to-face contact between the backside of the semiconductor wafer and the upper surface of the wafer support) the semiconductor wafer in a distributed manner, or structures that can support the semiconductor wafer via more restrictive contacts (such as an arcuate support that can contact the semiconductor wafer at multiple points along the outer circumference of the semiconductor wafer). The wafer support can include not only components that directly contact the semiconductor wafer, but can also include components or portions that extend beyond the outer circumference of the semiconductor wafer, such as an annular portion of a pedestal or ESC that extends beyond the outer circumference of the semiconductor wafer. In some cases, the structure of the wafer support can provide movement to the semiconductor wafer it supports, such as vertical movement and / or rotational movement. In some cases, the wafer support can also include lift pins as discussed above, or other mechanisms that can extend upward relative to the remainder of such a wafer support, thereby lifting the semiconductor wafer off the remainder of the wafer support. In some cases, the wafer support can include various removable components, such as edge rings.For example, certain wafer supports may be used with removable edge rings, which are designed to be removable by a wafer handling robot of a semiconductor processing tool and may interface with one or more non-removable edge rings, which are designed to be non-removable by a wafer handling robot of a semiconductor processing tool - such non-removable edge rings may still be removable by a technician, and for the purposes of this specification, such non-removable edge rings are considered part of the wafer support.

[0075] The present disclosure contemplates an auto-calibration system, such as may be used in conjunction with an AWC system (or similar device) and / or a wafer handling robot to provide, inter alia, an adaptive positioning system for auto-teaching an AWC system and / or a wafer handling robot of a semiconductor processing tool; since the chamber in which the teaching is performed can be sealed as it is during normal semiconductor processing operations, such a system can be used to auto-teach a wafer handling robot under vacuum or atmospheric pressure. Such an auto-calibration system can also enable the evaluation of various aspects of component or wafer placement and correction as needed to meet processing requirements. An auto-calibration system can also be used to guide the placement of an edge ring, which is a nominally annular structure and the inner diameter of which is typically slightly larger (or in some cases slightly smaller) than the outer diameter of a semiconductor wafer, thereby effectively "extending" the diameter of the semiconductor wafer during processing. The edge ring has an effect that causes an "edge effect", which deteriorates the process result uniformity occurring on the outer edge of the edge ring rather than on the semiconductor wafer itself.

[0076] Central to the auto-calibration system is an auto-calibration wafer, which may also be referred to as an adaptive positioning system (APS) wafer and can collect a large amount of information from sensors on various boards; this enables the auto-calibration wafer to be used as part of the overall auto-teaching process. Such an auto-calibration wafer can be used, for example, to perform diagnostic evaluations of components in a semiconductor processing tool and to obtain information that enables the operation of the semiconductor processing tool to be adjusted to improve wafer processing performance.

[0077] Generally, an auto-calibration wafer for a particular semiconductor processing tool may have a size and shape similar to that of the wafers and / or edge rings configured to be processed by the semiconductor processing tool, thereby enabling the wafer handling robot of the semiconductor processing tool to transfer the auto-calibration wafer in substantially the same manner as it transfers semiconductor wafers during processing. Thus, the size of the auto-calibration wafer can be adjusted to have a maximum height and diameter less than the minimum vertical and horizontal clearances of the channels of the semiconductor processing tool through which the wafer handling robot can transfer wafers.

[0078] As described above, an auto-calibration wafer may include various sensors - but the number and type of sensors may vary depending on the specific function provided by the auto-calibration wafer. It should be understood that an auto-calibration wafer according to the present disclosure may be used to provide any, some, or all of the sensors / functions discussed herein.

[0079] In addition to the various sensors that an auto-calibration wafer may include, the auto-calibration wafer may also include various components for controlling the sensors and obtaining data from the sensors, communicating with other components (such as the controller of a semiconductor processing tool), and / or storing and / or manipulating the data collected from the sensors. Thus, such an auto-calibration wafer may be linked to the controller of a semiconductor processing tool, introduced into the semiconductor processing tool, and then perform various sensing and data collection operations at various stages of a calibration routine or placement routine performed by the semiconductor processing tool via the actions of one or both of the controller(s) of the auto-calibration wafer and the controller(s) of the semiconductor processing tool. As will be appreciated from the examples discussed in more detail below, the semiconductor processing tool may perform such a calibration routine or placement routine with minimal or no human supervision.

[0080] Generally, an auto-calibration wafer may have a substrate, the overall shape of which is similar to the shape of a semiconductor wafer, e.g., generally circular, but it should be understood that in some cases, the auto-calibration wafer may have a different shape - for example, portions of the substrate that are not used to support sensors or other components, or that do not contact contact pads on the end effector or lift pins of the pedestal, may be omitted, which will result in openings or notches in the auto-calibration wafer. Additionally, in some implementations, the auto-calibration wafer may have a peninsula or other protrusion along its nominal circular outer edge, e.g., to support sensors at positions beyond the nominal outer diameter of the corresponding semiconductor wafer. The auto-calibration wafer may also include one or more indexing features such as a flat edge, notch, etc., along its outer edge to provide a mechanism for identifying the orientation of the auto-calibration wafer. The "center" of the auto-calibration wafer referred to herein should be understood as the point on the auto-calibration wafer that will be positioned at the same location as the location of the center of a semiconductor wafer or edge ring when the auto-calibration wafer is transported or positioned in a semiconductor processing tool in a similar manner as is typically used for transporting or positioning a semiconductor wafer or edge ring. It should be understood that while the center of the auto-calibration wafer may coincide with the geometric center of the substrate and / or the center of mass of the auto-calibration wafer, such alignment is not a requirement.

[0081] In most implementations, an auto-calibration wafer may have multiple downward-facing camera sensors, such as charge-coupled device (CCD) sensors or complementary metal-oxide semiconductor (CMOS) sensors, at various positions radially offset from the center of the auto-calibration wafer. Such an offset may be selected such that when the auto-calibration wafer is positioned, for example, above a semiconductor wafer placed on a wafer support of a semiconductor processing tool, each camera sensor has a field of view wide enough to capture a portion of the edge of the semiconductor wafer and a portion of the wafer support. If the semiconductor processing tool typically uses an edge ring during wafer processing operations, the camera sensors may be radially offset from the center of the auto-calibration wafer such that the field of view of the camera sensors is wide enough (when the edge ring is placed on the wafer support) to capture a portion of the edge ring. In some implementations of the auto-calibration wafer, the downward-facing camera sensors may be arranged in a circle having a diameter dimensionally the same as the semiconductor wafer configured for the semiconductor processing tool to process, for example, within ±10% or ±20% of the diameter of the semiconductor wafer. In another implementation, the downward-facing camera sensors may be arranged in a circle having a diameter between the semiconductor wafer configured for the semiconductor processing tool to process and the edge ring configured for the semiconductor processing tool to use. In some such implementations, the downward-facing camera sensors may be positioned along a diameter, for example, an average of the nominal outer diameter of the edge ring and the inner diameter of the edge ring or the nominal outer diameter of the semiconductor wafer, or within ±10% of the average. Such positioning may, for example, enable the downward-facing camera sensors to simultaneously capture, within their field of view, the outer edge of the wafer support (or the edge of features on the wafer support such as an ESC), the outer edge and / or inner edge of the edge ring, and the outer edge of the semiconductor wafer when the auto-calibration wafer is positioned generally centered on the wafer support (and when the semiconductor wafer and / or edge ring is centered on the wafer support).

[0082] Such placement of the imaging sensor enables the auto-calibration wafer to simultaneously obtain images of various fiducials associated with the wafer support, as well as the semiconductor wafer and / or the edge ring placed on the wafer support. As used herein, the term fiducial refers to a feature that is assumed to be substantially fixed relative to a particular structure, such as the circular edge of a component that can be used as a fiducial for the center point of that structure (it should be understood that such a fiducial may, for example, undergo changes in size and / or shape over time due to corrosion or deposition during wafer processing operations; such gradual changes in shape and / or size should not be considered in the context of the present disclosure as altering the "fixed" nature of such a fiducial). In the examples discussed herein, the fiducials used are features such as the outer edge of the semiconductor wafer, the outer edge and / or inner edge of the edge ring, the outer edge of the wafer support or the edge of a feature of the wafer support, a surface discontinuity in the wafer support (for example, the upper surface of the wafer support may have a circular protrusion that is surrounded by an annular surface that is recessed downward from the circular protrusion; the transition between the circular protrusion and the annular surface can be such a surface discontinuity), or any other feature suitable for the techniques discussed herein.

[0083] Next, an image of a given set of fiducials obtained for a semiconductor wafer, an edge ring, or other structure can be analyzed to determine the offset (or offsets) between reference points on two structures that are associated with these fiducials. For example, if the fiducials used are the circular outer edge of a semiconductor wafer and the circular inner edge of an edge ring surrounding the semiconductor wafer, then the relative size of the radial gap between the outer edge of the semiconductor wafer and the inner edge of the edge ring in each image can be determined and used to generate an estimate of the degree to which the center of the semiconductor wafer is offset from the center of the edge ring. In general, images from at least three camera sensors must be used to make such a determination (a similar technique can be implemented using images from only two camera sensors, but it is typically less accurate because some assumptions must be made about the relative sizes of the fiducials used). In some cases, some fiducials are not always visible, and in such cases intermediate fiducials may be required. For example, if a semiconductor wafer is centered on an ESC that has an outer diameter smaller than the wafer diameter and the outer edge of the ESC is used as a fiducial for such wafer placement, then an image in which both the outer edge of the ESC and the outer edge of the semiconductor wafer are visible can be obtained from a camera sensor that automatically aligns the wafer - thus any radial gap that exists between such edges cannot be identified and the degree of centering of the semiconductor wafer on the ESC cannot be directly determined. In such cases, an estimate of the degree of centering of the semiconductor wafer on the ESC can still be made using an intermediate fiducial such as the inner edge of an edge ring. For example, if an edge ring is placed on a wafer support such that it surrounds the ESC, then the radial gap between the inner edge of the edge ring and the outer edge of the ESC can be determined using the camera sensor that automatically aligns the wafer. Next, the center - to - center offset between the inner edge of the edge ring and the outer edge of the ESC can be determined based on the radial gap, and if necessary, the edge ring can be repositioned until the edge ring is centered on the ESC to an acceptable degree. After the edge ring is centered, the inner edge of the edge ring can serve as a "proxy" for the outer edge of the ESC; when the semiconductor wafer is subsequently placed on the wafer support and within the edge ring, an image of the radial gap between the outer edge of the semiconductor wafer and the inner edge of the edge ring can be obtained using the camera sensor of the automatically aligning wafer. Since the inner edge of the edge ring is centered on the outer edge of the ESC, the center - to - center offset between the outer edge of the semiconductor wafer and the inner edge of the edge ring can serve as a proxy for the center - to - center offset between the outer edge of the semiconductor wafer and the outer edge of the ESC. In such cases, based on the actually measured center - to - center offsets between the outer edge of the semiconductor wafer and the inner edge of the edge ring and between the inner edge of the edge ring and the outer edge of the ESC, the center - to - center offset between the outer edge of the semiconductor wafer and the inner edge of the edge ring is further fine - tuned.For example, if the edge ring is finally positioned such that there is an XY offset (15 μm, 10 μm) within an acceptable centering range between the center of the inner edge of the edge ring and the center of the outer edge of the ESC, and then a semiconductor wafer is placed such that the center of the outer edge of the semiconductor wafer has an XY offset (-5 μm, 12 μm) from the center of the inner edge of the edge ring (in the same coordinate system), then the XY offset between the center of the semiconductor wafer and the center of the outer edge of the ESC can be determined by summing the two offset pairs, e.g., (15 μm - 5 μm, 10 μm + 12 μm) = (10 μm, 22 μm), e.g., a total offset of approximately 24 μm.

[0084] Once the fiducials of the two structures are imaged by the auto-calibration wafer and the offset between the two structures is determined, the offset can be compared with an offset threshold, which can represent the maximum offset acceptable for proper operation of the semiconductor processing tool between the two structures. If the offset exceeds the offset threshold, the semiconductor processing tool can be made to take corrective action.

[0085] Although various techniques can be used to determine the center-to-center offset between two structures and these techniques are considered to fall within the scope of the present disclosure, Figure 1 an exemplary technique for determining such an offset is provided in the context of Figure 1 Examples of calibration wafers shown relative to the edge ring are provided. In Figure 1 an edge ring 162 is shown and a calibration wafer 160 is placed within the inner diameter of the edge ring 162. For clarity, the term calibration wafer or reference wafer as used herein refers to a wafer whose dimensions are equal to or similar to a typical semiconductor wafer processed by a semiconductor processing tool - the calibration wafer is intended to replace, for example, a normal wafer that can be processed by the semiconductor processing tool. The calibration or reference wafer may in some cases include calibration marks or other features that can be recognized by machine vision algorithms to assist in centering and calibration operations. The term auto-calibration wafer as used herein refers to a "smart" wafer or otherwise equipped with sensors and other electronics such that such an auto-calibration wafer can obtain data and measure various parameters related to the performance of the semiconductor processing tool.

[0086] Figure 1The calibration wafer 160 and the edge ring 162 are not shown to scale to more easily show, for example, the misalignment between the edge ring 162 and the center of the calibration wafer 160 (shown as a cross) and the gap between the outer edge of the calibration wafer 160 and the inner edge of the edge ring 162. The calibration wafer 160 may include sets of calibration marks 170 which, in this example, may be positioned along the outer circumference of the calibration wafer and spaced at a known amount (e.g., 120°). The first camera sensor facing down of the automatically calibrated wafer may be positioned such that the calibration marks 170 and the gap 164 between the edge ring 162 and the calibration wafer 160 both fall within the field of view 128 of the first camera sensor.

[0087] In such a technique, certain assumptions can be made about various factors - for example, it can be assumed that the diameter of the calibration wafer is a known amount, such as 300 mm. Thus, it can be assumed that the radius r from the center point of the self - calibration wafer 160 to the edge of the calibration wafer w is constant (there may be some portions along the edge of the calibration wafer with a shorter radius, such as an index flat edge or notch along the edge, but the calibration wafer can have a constant radius within the field of view of the first camera sensor). As described above, the calibration wafer may also have, for example, calibration marks 170, and the positions of the calibration marks 170 will be very well - defined. In this example, it is known that the calibration marks 170 are spaced 120° around the circumference of the calibration wafer. The calibration marks may include, for example, features such as radial lines (which are recognizable in the image data and used to establish a direction vector along which the gap 164 is evaluated in each image) and squares (as shown) or circles that may have a known size, such as 2 mm. The known size can be used to judge the scale of the features being imaged. For example, if the gap 164 is identified in the image as having a size that is 0.23 times the size of the edge of the 2 - mm calibration mark square in the same image, then the size of the gap is judged to be 0.23 * 2 mm = 0.46 mm. In some implementations, such calculations may take into account, for example, image distortion caused by lens effects (such as using a chessboard pattern) using machine vision or optical image correction techniques, and may correct such distortion using, for example, calibration data associated with the automatically calibrated wafer.

[0088] It should be understood that in some implementations, the calibration marks discussed above may be omitted, and fiducials such as the circular edges of various components may be used without determining the center position of such components.

[0089] If it is assumed that the center of the calibration wafer 160 is also used as the origin of the coordinate system, in which the offset of the edge ring 162 centered on the center of the calibration wafer 160 is to be determined, the center position of the edge ring can be solved in the following manner: Determine the positions of three points along the inner edge (or outer edge) of the edge ring 162, and then determine the center position of the circle defined by these three points. Once the center position of the edge ring 162 in the coordinate system of the calibration wafer is known, it is a simple process to extract the center-to-center offset between the two components.

[0090] The gap 164 and the radius r of the calibration wafer 160 can be used w and the angle along which each gap 164 lies can be measured to determine the positions of three points along the inner edge of the edge ring 162. For example, for the gap 164 δ 1 , the gap δ 1 can be added to the radius r w to obtain the radial distance from the calibration wafer origin / center to the inner edge of the edge ring 162. The XY coordinate pair of the point where the gap terminates at the inner edge of the edge ring can be determined using trigonometric relationships based on the angular position of the radius extending from the center of the calibration wafer to the point where the gap terminates at the inner edge of the edge ring 162. In this example, the angular position of this radius is 0 degrees. Thus, the XY coordinates of such a point can be determined according to the following equations:

[0091] X = (r w + δ x )·sin(θ)

[0092] Y = (r w + δ x )·cos(θ)

[0093] where δ x is the relevant gap distance, r w is the calibration wafer radius, and θ = the angle between the radius extending from the calibration wafer origin to the gap and the polar axis extending from the origin.

[0094] Thus, for example, if r w = 150 mm, δ 1 = 17.338 mm, δ 2 = 22.823 mm, and δ 3 = 37.69 mm, then:

[0095] Gap δ <![CDATA[r w > θ X Y 1 17.338 mm 150 mm 0° 0 mm 167.34 mm 2 22.823 mm 150 mm 120° 149.67 mm -86.41 mm 3 37.69 mm 150 mm 240° -162.5 mm -93.85 mm

[0096] It should be understood that the dimensions provided above are based on Figure 1is scaled up or down, and values of δ of this kind are impractically large for typical semiconductor processing tools and wafer handling robots. In actual operation, the obtainable values of δ can generally be about less than 1 mm, such as less than 800 μm.

[0097] Once three coordinate pairs of the XY coordinates for positions along the inner edge of the edge ring are known, the position of the center of the edge ring 162 relative to the origin of the coordinate system (the center of the calibration wafer) can be determined using the following equations:

[0098]

[0099]

[0100] where (x 1 , y 1 ), (x 2 , y 2 ), and (x 3 , y 3 ) are each coordinate pairs, and (x c , y c ) is the coordinate pair of the center of the edge ring. Thus, in the present example, (x c , y c ) = (-8.378 mm, -8.618 mm). After forming the center offset between the edge ring and the calibration wafer, appropriate actions can be taken to reduce the center offset between the two components. For example, in the present case, the edge ring can be retrieved by the wafer handling robot and then moved in a manner reverse to the offset, such as (+8.378 mm, +8.618 mm), to center the edge ring on the calibration wafer. Alternatively, the calibration wafer can be moved by the offset (-8.378 mm, -8.618 mm) to center the calibration wafer on the edge ring. If the automatic calibration wafer coordinate system is not aligned with the coordinate system used by the wafer handling robot, the center-to-center offset obtained using the automatic calibration wafer can be converted to an equivalent offset in the coordinate system used by the wafer handling robot before using the wafer handling robot to correct the placement of, for example, the edge ring. Once the calibration wafer is centered in an acceptable manner, the AWC of the semiconductor processing tool can then be trained using the calibration wafer. Various techniques related to using an automatic calibration wafer to facilitate centering operations in a semiconductor processing tool will be discussed in more detail below, but first an overall description of the various features of the automatic calibration wafer will be presented.

[0101] Figure 2 shows a schematic diagram of an exemplary automatic calibration wafer with a dashed / shaded area that shows the wafer support, edge ring, and calibration wafer positioned thereunder. In Figure 2Figure 0 shows that the automatic calibration wafer 200 includes a substrate 202, and a plurality of different sensors and other electrical components are mounted on the substrate 202. Additionally, as shown in Figure 2 Figure 1, although the calibration wafer 260, the annular edge ring 262, and the wafer support 252 are not part of the automatic calibration wafer 200; it is shown that these additional components are concentrically arranged with the automatic calibration wafer 200, as if during certain stages of normal use, the calibration wafer 260, the edge ring 262, the wafer support 252, and the automatic calibration wafer 200 are all centered relative to each other. In the example shown, it is shown that the diameter of the automatic calibration wafer 200 is larger than that of the wafer support 252, the edge ring 262, and the calibration wafer 260 - in actual practice, the size of the automatic calibration wafer 200 may be similar to the size of the calibration wafer 260. As previously mentioned, the wafer support 252 may include a plurality of components, such as an ESC that may be slightly smaller than the diameter of the calibration wafer 260, and a support structure that may extend beyond the ESC and support the edge ring 262. For simplicity, such a separate structure is not shown in Figure 2 Figure 2.

[0102] is shown as Figure 2 The sensors that are part of the exemplary automatic calibration wafer shown in Figure 3 may include, for example, a plurality of first camera sensors 222, and the plurality of first camera sensors 222 may be, for example, CCD or CMOS devices. The first camera sensors 222 can be used in conjunction with an optical or other focusing system, and their arrangement provides a downward-looking field of view. As shown in Figure 2As shown, the field of view 228 of the first imaging sensor 222 is: when the automatic calibration wafer 200 is positioned at a predetermined height or within a height range above the calibration wafer 260, the edge ring 262, and the wafer support 252 (such as the height at which the end effector of the wafer handling robot normally is when transporting the wafer to the wafer support 252), a long rectangular area spanning the outer edge of the calibration wafer 260, the inner and outer edges of the edge ring 262, and the outer edge of the wafer support 252. The field of view 228 of each first imaging sensor 222 can be any of various shapes, such as circular or oval, and can also extend radially outward to a lesser extent than shown. For example, in some implementations, the field of view 228 of the first imaging sensor 222 may only extend far enough to capture the inner edge of the edge ring 262 but not the outer edge of the edge ring 262. By positioning the first imaging sensor 222 such that the first imaging sensor 222 is generally directly above the outer edge of the calibration wafer 260 and the inner edge of the edge ring 262 (if used), the first imaging sensor 222 can be positioned to obtain image data that accurately reflects the dimensions of any gaps that may exist between various fiducials (such as the edges of such components) in the image. In particular, such placement of the imaging sensor can reduce the impact that height mismatches may have on the determination of the gap dimensions, resulting in a more accurate gap dimension estimate. For example, if the imaging sensor obtains gap image data along a line of sight with a very narrow angle relative to the automatic calibration wafer (such as the case where the imaging sensor is mounted near the center of the automatic calibration wafer), any slight variation in the height of either the edge ring or the calibration wafer will be amplified and cause the gap dimension to fluctuate in an unpredictable manner. Positioning the imaging sensor near the outer edge of the automatic calibration wafer can significantly reduce the impact caused by such effects.

[0103] In addition to the first imaging sensor 222, in some cases the auto-calibration wafer 200 may also include an imaging sensor, such as a second downward-facing imaging sensor 224 located at the center. The second imaging sensor 224 may be configured to obtain an image directly below the center of the auto-calibration wafer. Such an imaging sensor can be used in a calibration routine where the fiducial to be imaged is located near the position that is typically the center of the semiconductor wafer placement. For example, the wafer support for receiving the wafer may have a cross fiducial mark at the center of the wafer support, and the cross fiducial mark can be imaged by the second imaging sensor to assist in positioning the center of the wafer support relative to the auto-calibration wafer. For example, the wafer support may have a fiducial at the middle, and when the end effector of the wafer handling robot positions the auto-calibration wafer 200 above the wafer support, the fiducial can be imaged by the second imaging sensor 224 to facilitate teaching the wafer handling robot the position of the wafer support. Such sensors can also be used to center the auto-calibration wafer on the end effector of the wafer handling robot. For example, the end effector of the wafer handling robot may include a fiducial that is generally located at a position observable by the second imaging sensor 224 when the auto-calibration wafer 200 is generally centered above the end effector. When actuating the wafer handling robot to retrieve the auto-calibration wafer, the end effector can move below the auto-calibration wafer to cause the fiducial to fall within the field of view of the second imaging sensor 224. Then the second imaging sensor 224 can be caused to obtain an image of the fiducial, and the image of the fiducial can be analyzed to determine how far off-center the fiducial is relative to the center of the auto-calibration wafer 200. Then the wafer handling robot can be caused to reposition the end effector to reduce the off-centerness of the fiducial relative to the auto-calibration wafer 200 to an acceptable limit. It should be understood that other implementations of the auto-calibration wafer 200 discussed herein may use other sensors that are not imaging sensors to obtain radial clearance data and / or centerness data. For example, ultrasonic sensors can be used to obtain a contour map that can display a three-dimensional fiducial, and the manner of determining the above distances and clearances from the contour map can be similar to the manner of determining such distances and clearances from imaging data. It should be understood that any sensor that can be used to evaluate the clearances between the above fiducials and / or the centerness of the auto-calibration wafer 200 relative to the wafer support can be used to replace the imaging sensor discussed above.

[0104] Some implementations of the auto-calibration wafer 200 may also include various non-imaging sensors, such as one or more vibration sensors 230, one or more orientation / tilt sensors 232, and / or one or more proximity sensors 234.

[0105] A vibration sensor 230 can be used to detect vibrations experienced by an auto-calibrating wafer during various operations such as wafer handling robot operations or lift pin retraction or extension. For example, in some wafer stations, the wafer support can be a pedestal or similar structure and can include a plurality (e.g., three) of lift pins, which are thin pins that can move vertically relative to an electrostatic chuck (ESC) or other wafer support structure. Such lift pins are typically arranged in an equilateral triangle within a circular boundary defined by a semiconductor wafer centered on the wafer support. Thus, when the lift pins are in the extended position relative to the surface of the wafer support, the lift pins can support any wafer present at the wafer station. When the lift pins are retracted into the wafer support, the supported wafer is thereby brought into contact with the upper surface of the wafer support. During such lift pin retraction, the wafer can experience small vibrations, such as those caused by equipment wear and tear. One or more vibration sensors can be used to evaluate the nature of such vibrations and provide an indication of the health status of the lift pin mechanism. The vibration sensor can include, for example, an accelerometer, a piezoelectric vibration sensor, an optical distance measurement sensor, or an optical microphone (such sensors can detect vibrations, for example, by measuring the displacement of the substrate of the auto-calibrating wafer relative to the wafer support, thereby providing insight into the degree of vibrations experienced), as well as other types of sensors.

[0106] One or more orientation / tilt sensors 232 can be used to evaluate whether the wafer support or other components are supporting the auto-calibrating wafer (and thus other wafers) in a horizontal manner. For example, if one of the lift pins of the wafer support becomes shorter or longer than the other lift pins, the wafer supported by the lift pins will thereby exhibit a slight degree of tilt. Such tilt can cause one side of the wafer to contact the wafer support before the other side of the wafer, which can result in a slight change in the way the wafer is placed on the wafer support and, in some cases, can cause some sliding between the lift pins and the wafer during placement of the wafer on the wafer support (which can damage the wafer and / or cause particulate contamination). In addition, such sensors can be used to evaluate the levelness of the wafer support itself after the auto-calibrating wafer has been placed on the wafer support. Thus, the levelness of both the wafer support and other equipment can be evaluated using an auto-calibrating wafer with an orientation sensor. The orientation sensor can include, for example, an accelerometer and an inclinometer or clinometer.

[0107] Figure 3 A wafer support 352 with extended lift pins 372 is shown, with the lift pins 372 supporting an auto-calibrating wafer 300. The lift pins 372 can be retracted downward (and / or the wafer support 352 can be displaced upward) to place the auto-calibrating wafer 300 on the wafer support 352.

[0108] One or more proximity sensors 234 can be used to evaluate the height of various structures at the wafer station. For example, it may be desirable to evaluate the height of the edge ring or the height of the portion of the edge ring that is above the wafer support (e.g., the ESC above the wafer support, around its circumference) (a non-uniform circumferential height of the edge ring may develop or increase process non-uniformity). If the proximity sensor is disposed in the auto-calibration wafer and positioned such that a direct or indirect distance measurement between the auto-calibration wafer and the edge ring (or other structure) is allowed, the obtained data can be used to determine the uniformity of the height of the edge ring or its portion along its circumference.

[0109] In other implementations of the auto-calibration wafer, the auto-calibration wafer can be placed on the edge ring such that it can be supported by the edge ring. In some such implementations, the auto-calibration wafer can have one or more portions that extend beyond the inner diameter of the edge ring and sit on the uppermost surface of the edge ring (whereas semiconductor wafers intended to be used with the edge ring will typically be fully contained within the inner diameter of the edge ring). However, in other such implementations, the size of the auto-calibration wafer can be adjusted such that its diameter is similar to that of a semiconductor wafer configured to be used with the edge ring. In certain such implementations, the edge ring can have a stepped inner diameter, e.g., the diameter of the upper surface of the edge ring can be slightly larger than the diameter of the semiconductor wafers to be used with the edge ring, while the diameter of the lower surface of the edge ring can be slightly smaller than the diameter of those semiconductor wafers. The resulting geometry is a concave annular surface in the edge ring, which can be used to support the semiconductor wafer during processing. Thus, the auto-calibration wafer supported by such an edge ring has a small gap between it and the wafer support that supports the auto-calibration wafer. A proximity sensor can be used to determine the size of this gap at various locations along the circumference of the auto-calibration wafer / edge ring. The obtained measurements can be analyzed to determine the levelness or thickness variation in the portion of the edge ring between the wafer support and the auto-calibration wafer.

[0110] Figure 4 A side view of an auto-calibration wafer having a set of proximity sensors is shown, which can be used to determine the edge ring height. In Figure 4 , the edge ring 462 is positioned on the wafer support 452. The auto-calibration wafer 400 is positioned such that it is on the circumferential shelf of the edge ring 462 and thus slightly suspended above the wafer support 452. As can be seen, the edge ring has a certain height in a non-uniform shelf region - the right side of the shelf is higher than the left side, such that the auto-calibration wafer 400 has an inclination angle with respect to the wafer support 452 and the edge ring 462. The proximity sensors 434 in the auto-calibration wafer 400 can be configured to measure the distance between each proximity sensor 434 and the nearest facing surface, such as the upper surface of the wafer support 452. In this case, the left proximity sensor 434 has measured the distance Δ 1, and the right proximity sensor 434 has measured a distance Δ 2 . These distances can be evaluated for one or more conditions to determine whether the edge ring height exceeds an allowable value. For example, in some implementations, if |Δ 1 - Δ 2 | > x or max(Δ 1 , Δ 2 ) > y, then the edge ring can be considered to have an edge ring height that exceeds the limit and corrective action can be taken, such as a new edge ring must be installed.

[0111] In some such implementations, two sets of proximity sensors are provided on the auto-calibration wafer - one set is positioned to obtain distance measurements between the auto-calibration wafer and the edge ring, and the other set is positioned to obtain distance measurements between the auto-calibration wafer and a non-edge-ring structure, such as a calibration wafer placed in the middle of the edge ring or on the surface of the wafer support. In such an implementation, the auto-calibration wafer can be positioned directly above the edge ring supported, for example, by lift pins or a wafer handling robot, and proximity sensors can be used to obtain distance measurements between the auto-calibration wafer and the edge ring and between the auto-calibration wafer and other structures. In such an implementation, the size of the auto-calibration wafer can be adjusted to be larger than a typical semiconductor wafer used in a semiconductor processing tool (or have portions that protrude beyond the diameter of the semiconductor wafer) so that it radially overlaps the edge ring and has sufficient margin for some of the proximity sensors mounted thereon to radially overlap the edge ring and determine the distance between the upward-facing surface of the edge ring and those proximity sensors. Other proximity sensors can be located on the auto-calibration wafer so that they radially overlap the central opening of the edge ring, such that these proximity sensors can obtain distance measurements between the auto-calibration wafer and, for example, a calibration wafer placed in the center of the edge ring, or the exposed surface of the wafer support (if a similar wafer is not present).

[0112] By simultaneously obtaining measurements from the two sets of proximity sensors and subtracting the distance of, for example, the auto-calibration wafer / edge ring from the distance of the corresponding auto-calibration wafer / wafer support or auto-calibration wafer / calibration wafer, an estimated value of the edge ring height can be determined at each proximity sensor location.

[0113] Figure 5 A side view of another auto-calibration wafer with two sets of proximity sensors is shown, each set of proximity sensors being arranged along circular paths of different diameters. In Figure 5In this case, the end effector 558 of the wafer handling robot will automatically calibrate the wafer 500 to be supported above the wafer support 552 and the edge ring 562. The outermost proximity sensors 534 are located at radial positions that radially overlap the edge ring 562 when the wafer 500 is automatically calibrated to be nominally centered above the edge ring 562, and the innermost proximity sensors 534 are located at radial positions that radially overlap the interior of the edge ring 562. The proximity sensors 534 can be controlled to simultaneously determine the distance between the proximity sensors 534 and the surface directly below the proximity sensors, such as distances Δ 1a , Δ 2a , Δ 1b , and Δ 2b . These distances can be evaluated to determine whether the height of the edge ring has changed beyond an acceptable range. For example, if |Δ 2a - Δ 2b | > x or max(Δ 2a , Δ 2b ) > y, or if |(Δ 1a - Δ 1b ) - (Δ 2a - Δ 2b )| > x or max(((Δ 1a - Δ 1b ), (Δ 2a - Δ 2b )) > y, then the height of the edge ring can be considered to have exceeded the allowable threshold. In some such implementations, this measurement can be used to create a closed-loop system where the edge ring lift pins can be actuated to adjust the height of the edge ring above the wafer support (e.g., above the ESC) to maintain the height of the edge ring above the wafer support (e.g., above the ESC) at an optimal value. Similar techniques can be used to initially calibrate the edge ring lift pins, such as to determine the respective heights at which each edge ring lift pin must be located in order to keep the edge ring level relative to the wafer support. For clarity, it should be noted that the wafer support can have multiple sets of lift pins - for example, one set can include lift pins located at positions within the area of the wafer support where the semiconductor wafer is to be placed, while another set can include lift pins located outside of this area but within the interval of the wafer support occupied by the edge ring. Each set of lift pins can be actuated separately to raise or lower the semiconductor wafer, or to raise and lower the edge ring.

[0114] Various types of proximity sensors can be used, including, for example, capacitive distance sensors, inductive distance sensors, optical distance sensors, etc. In some cases, automatically calibrating the wafer can include one or more other types of sensors, such as temperature sensors, pressure sensors, humidity sensors, light sensors, and so on.

[0115] The various sensors included in the auto-calibration wafer can be communicatively coupled to a first controller 208 that can include one or more first processors 210 and one or more first memories 212. The first controller 208 can also be electrically coupled to a power source 214 such as a battery, a capattery, or other power source. In some implementations, the power source 214 can be operatively coupled to a charging feature using electrical contact pins that are positioned to align with charging features at a docking station where the auto-calibration wafer 200 is stored when the auto-calibration wafer 200 is placed in the docking station. In Figure 2 the illustrated implementation, a wireless charging feature 216 is shown, which can be, for example, an inductive charging coil such as a Qi-compatible inductive charging coil or other suitable wireless charging interface. In such a case, the docking station for storing the auto-calibration wafer 200 can have a similar wireless charging interface that is configured to charge the auto-calibration wafer 200 when the auto-calibration wafer 200 is placed therein.

[0116] The first controller 208 can also be communicatively coupled to a first wireless communication interface such as WiFi, Bluetooth, or other wireless communication interface, such that instructions and / or data can be sent from and / or sent to the first controller 208 and thus can be sent from and / or sent to the auto-calibration wafer 200. For example, a semiconductor processing tool docked with the auto-calibration wafer 200 can include a second controller having one or more second processors and one or more second memories. The second controller can be communicatively coupled to a second wireless communication interface and can then be used to dock with the first wireless communication interface of the auto-calibration wafer. Thus, the auto-calibration wafer 200 may be able to wirelessly communicate with the semiconductor processing tool such that information, instructions, and other data can be transferred between the auto-calibration wafer 200 and the semiconductor processing tool.

[0117] Figure 6 is a photograph of an exemplary auto-calibration wafer. The auto-calibration wafer 600 includes a substrate 602 having printed circuit lines that provide electrical connections between various components including a power source 614, which is a rechargeable battery in this example, a processor 610, a memory device 612, and a wireless charging feature 616 that can be used to inductively transfer energy to the rechargeable battery during wireless charging. Figure 6 Also visible in are three first camera sensors 622 mounted at equidistant positions along the circumference of the substrate 602 and a second camera sensor 224 mounted at the center. In the vicinity of each first camera sensor 622 is a corresponding proximity sensor 634, which is a capacitive proximity sensor in this example.

[0118] Figure 7Line drawing plan view of another exemplary auto - calibration wafer 700. In this example, the auto - calibration wafer 700 has a generally circular substrate 702 which has three ears dispersed along its outer circumference, each ear accommodating a corresponding first imaging sensor 722. In this example, the substrate 702 generally has the same diameter as a typical semiconductor wafer; these ears extend beyond the diameter and enable the first imaging sensor 722 to be positioned such that the photosensitive area of the first imaging sensor 722 can be centered, for example, above the outer edge of the semiconductor wafer which is placed below and centered on the auto - calibration wafer 700. In this example, the auto - calibration wafer 700 also includes two power supplies 714, such as rechargeable batteries that can be charged using wireless charging features 716 (such as inductive charging coils). The batteries can power various electrical components of the auto - calibration wafer 700 such as a processor 710, a memory 712, a wireless communication interface 718, a first imaging sensor 722, a second imaging sensor 724, a proximity sensor 734, and an accelerometer 736 (which can be used as an orientation or tilt sensor).

[0119] Figures 8a to 8i Schematic illustration of a semiconductor processing tool during various stages of using an auto - calibration wafer. In Figure 8a a portion of the semiconductor processing tool is shown. The portion of the semiconductor processing tool shown includes two wafer stations 844a and 844b, but the tool may also include other wafer stations. Each wafer station corresponds to a location where one or more wafers can be placed during various operations performed in the semiconductor processing tool. The wafer stations can be, for example but not limited to, in one or more processing chambers of the tool, in a buffer for storing wafers before or after processing, in an airlock or load lock that enables the transfer of wafers between environments of different pressures, in a load port, in a front - opening unified pod (FOUP) that can dock to a load interface, etc. In Figure 8a , the wafer station 844a is provided by the semiconductor processing chamber 850; in contrast, the wafer station 844b is provided by a docking station 868 dedicated to storing the auto - calibration wafer 800 (although such a dedicated docking station may not be included in some implementations). The docking station 868 can have features (not shown) to charge the auto - calibration wafer 800 or can otherwise be configured to interface with various aspects of the auto - calibration wafer 800. In some implementations, the docking station can be located in a vacuum transfer module (VTM) (or attached to the VTM) so that it can be accessed by a wafer handling robot in the vacuum transfer module, and then the auto - calibration wafer can be used to train the wafer handling robot. In other implementations, the docking station can be located in an equipment front - end module (EFEM) or other atmospheric or near - atmospheric pressure locations, in which case the auto - calibration wafer can first be retrieved by a wafer handling robot located in the EFFM and then transferred to another wafer handling robot located in the VTM.

[0120] Each wafer station 844 may have an associated wafer support 852, such as wafer support 852a / base 854 of wafer station 844a (the wafer support in wafer station 844b is not shown but it may have a wafer support that can receive the auto-calibration wafer 800 when the auto-calibration wafer 800 is placed in the wafer station). In some cases, the wafer station may be associated with an Active Wafer Centering (AWC) system 866, and the AWC may obtain a measurement of the wafer center position when importing a wafer into the associated wafer station 844 or removing a wafer from the associated wafer station 844. In this example, the AWC system 866 is associated with wafer station 844a and includes two vertically oriented beam sensors (represented by dots within the AWC system 866), and the beam sensors can detect when the wafer edge crosses either beam. As discussed previously, the AWC system 866 can be used to determine the center position of the wafer supported by the end effector 858 of the wafer handling robot 856 of the tool relative to a particular known reference frame, thereby enabling determination of whether any positioning correction is needed before placing the wafer at the desired location.

[0121] As Figure 8a shown, when preparing to place the edge ring 862 onto the wafer support 852a / base 854, the wafer handling robot 856 supports the edge ring 862 on the end effector 858. During this time, the auto-calibration wafer 800 is temporarily stored in the wafer station 844b / docking station 868.

[0122] In Figure 8b it, the wafer handling robot 856 has been actuated to place the edge ring 862 at a position nominally centered on the wafer support 852a / base 854, and the wafer handling robot 856 has also been further actuated to retrieve the auto-calibration wafer 800 from the wafer station 844b / docking station 868.

[0123] In Figure 8c it, the wafer handling robot 856 has retrieved the auto-calibration wafer 800 from the wafer station 844b / docking station 868 and is ready to position the auto-calibration wafer above the wafer support 852a / base 854 and the edge ring 862.

[0124] In Figure 8dIn [description], the wafer transfer manipulator 856 has extended the end effector 858 to position the auto-calibration wafer 800 above the wafer support 852a / base 854 and the edge ring 862; thus, the auto-calibration wafer 800 is positioned such that the field of view of the downward-facing first camera sensor of the auto-calibration wafer 800 (represented by three rectangular points spaced along the outer edge of the auto-calibration wafer 800) includes the edge ring 862 and one or more features of the wafer support 852a / base 854. Then, the second controller 842 can cause the first controller of the auto-calibration wafer 800 to obtain image data of, for example, the gap between the inner edge of the edge ring 862 and a reference of the wafer support 852a / base 854, such as the outer edge of the ESC of the wafer support 852a. As discussed previously, these gaps can be used to determine the offset of the longitudinal direction of the edge ring 862 relative to the center of the wafer support 852a / base 854; if the offset exceeds an allowable threshold, the edge ring can be repositioned to reduce the offset. In this example, the edge ring has been placed in an acceptable manner and, as Figure 8e shown in [description], the wafer transfer manipulator 856 can remove the auto-calibration wafer 800 from the wafer station 844a and return the auto-calibration wafer 800 to the wafer station 844b.

[0125] In Figure 8f [description], the wafer transfer manipulator has been actuated to retrieve the calibration wafer 860, which may also be stored in the docking station 868 and, for example, below or above the auto-calibration wafer 800, or can be obtained from a completely different location such as a load interlock or an air lock. Then, the calibration wafer 860 can be placed in the wafer station 844a / semiconductor processing station 850 and transferred to the wafer support 852a / base 854 such that it is nominally centered relative to the center of the edge ring 862 as Figure 8g shown in [description].

[0126] In Figure 8h [description], the wafer transfer manipulator has been actuated to retrieve the auto-calibration wafer 800 from the wafer station 844b / docking station 868; in Figure 8i [description], the wafer transfer manipulator has been further actuated to position the auto-calibration wafer 800 above the wafer support 852a / base 854, the calibration wafer 860, and the edge ring 862. Similar to Figure 8d [description], the auto-calibration wafer 800 can then be controlled to obtain image data of the gap between the edge ring 862 and the calibration wafer 860, such as the gap 864, thereby determining any offset between the center of the calibration wafer 860 and the center of the edge ring 862.

[0127] Various techniques that can be implemented with the auto-calibration wafer, such as the techniques discussed above, will be explored in more detail below with reference to Figures 9 to 14 [description].

[0128] Figure 9 Figure 9 shows a flowchart of a technique for determining the position of a reference point of a structure at a wafer stage using an auto-calibration wafer. Such a technique can be used, for example, to teach a wafer handling robot the various positions where a wafer may be placed (or retrieved). In block 902, the end effector of the wafer handling robot can be used to retrieve the auto-calibration wafer; in block 904, the auto-calibration wafer can be centered on the end effector of the wafer handling robot (in some implementations, blocks 902 and 904 can be performed simultaneously). For example, the auto-calibration wafer can be placed on the end effector such that the center of the auto-calibration wafer (or some other known reference point on the auto-calibration wafer) is centered on the known reference point of the end effector, thereby establishing the spatial relationship between the two reference points and allowing the measurements obtained using the auto-calibration wafer to be mapped or transformed into the coordinate system used by the wafer handling robot.

[0129]

[0129] Such placement of the auto-calibration wafer on the end effector can be accomplished via any suitable mechanism, including via the use of physical indexing features or other contact-based means to ensure that the auto-calibration wafer is properly positioned on the end effector. However, in some cases, the imaging features of the auto-calibration wafer itself can alternatively be used to ensure that the auto-calibration wafer is centered on the end effector. For example, before the auto-calibration wafer is loaded onto the end effector, the auto-calibration wafer can be positioned above the end effector and one or more of the imaging sensors of the auto-calibration wafer can be activated to obtain an image of the end effector or its area. The portion of the end effector that is imaged can include, for example, fiducials that define the reference points on the end effector, such as the position on the end effector that coincides with the XY center point of a theoretical semiconductor wafer that is perfectly placed on the end effector. The image data can then be analyzed to determine the offset between the reference point of the auto-calibration wafer, such as the center of the auto-calibration wafer, and the reference point / fiducial of the end effector. The wafer handling robot can then be actuated to move the end effector in a manner that reduces or eliminates the offset before the auto-calibration wafer is placed on the end effector, thereby centering the auto-calibration wafer on the end effector.

[0130]

[0130] In block 906, a wafer stage for calibration can be selected. The calibration is, for example, to determine the structure of the wafer stage, such as the reference point on the wafer support. The reference point is, for example, the position where the center of the wafer to be transported to the wafer stage is expected to be located. In block 908, the wafer handling robot can be actuated to position the end effector and the auto-calibration wafer above the selected wafer stage such that the auto-calibration wafer is generally centered above the reference point of the wafer support of the selected wafer stage. Such an initial positioning can be based on, for example, an estimate of the wafer support reference point position and in most cases can generally keep the placement accuracy within one millimeter or a few millimeters. The estimate can be based on the positions of various components in the system during design.

[0131] In block 910, an image data of one or more fiducials on a target structure located at a selected wafer station can be obtained for the auto-calibration wafer; the one or more fiducials can be related to a reference point of the wafer station, and the reference point is, for example, the position where the center of the wafer to be transported to the wafer station is expected to be located. For example, the outer edge of the ESC of the wafer support at the selected wafer station can be used as a fiducial; such a fiducial may not directly indicate the reference point of the wafer station, but can clearly define the reference point. For example, the circular or arc-shaped edge of the ESC can define the center point used as the reference point. In another example, the wafer support can include some type of fiducial, such as an etched "+", or other marks directly indicating the reference point. For example, the center of the wafer support can be the reference point and the intersection of the two lines in the "+" can represent the reference point.

[0132] In block 912, the position of the reference point of the structure (such as the wafer support) of the selected wafer station associated with the auto-calibration wafer can be determined based on the image data of the fiducial. For example, the image data can indicate an XY offset between the reference point of the structure and the reference point of the auto-calibration wafer. The reference point of the auto-calibration wafer is, for example, the center (0.3 mm, 0.5 mm) of the auto-calibration wafer in the coordinate system of the auto-calibration wafer.

[0133] In block 914, the position of the reference point of the structure can then be determined relative to the wafer handling robot coordinate system. For example, the XY offset determined in block 912 relative to the coordinate system of the auto-calibration wafer can undergo a coordinate system transformation to convert it into equivalent coordinates in the wafer handling robot coordinate system, for example, to address a possible angular misalignment between the coordinate system of the auto-calibration wafer and the coordinate system of the wafer handling robot.

[0134] If the Figure 9 calibration technique is used, it may be desirable in some cases to calibrate the auto-calibration wafer before implementing this calibration technique. For example, it may be desirable to establish the position of the camera sensor or the sensor used to obtain the image data relative to a reference point such as the center point of the auto-calibration wafer to appropriately process the position information determined from such a sensor. Each camera sensor can be considered, for example, to provide XY position data in a coordinate system (based on the rectangular or linear array of pixels that each such sensor may have), and this coordinate system is specific to each camera sensor and is offset from the reference point of the auto-calibration wafer by a specific XY distance and / or rotation angle. Calibrating the auto-calibration wafer can determine such XY and angular offsets for the coordinate system of each camera sensor. Any position subsequently determined from the camera sensor data can be appropriately transformed to accurately locate relative to the coordinate system of the reference point of the auto-calibration wafer.

[0135] In one example of such calibration, an auto-calibration wafer may be placed in a fixture that has index pins or other alignment features that contact the outer edge of the auto-calibration wafer and physically restrict the auto-calibration wafer from being centered above a datum that is part of the fixture and known to be centered relative to the restricted outer edge of the auto-calibration wafer. Once the auto-calibration wafer is installed in the fixture and centered above the datum, an already centered imaging sensor may be made to acquire an image of the datum, and then a determination may be made, for example, as to which pixel or pixels coincide with the center point indicated by the datum, thereby providing information that can later be used to convert any position data obtained from an image of the already centered imaging sensor into a coordinate system related to a reference point. Similar datums may be provided at locations in the fixture that coincide with the fields of view of other imaging sensors, thereby allowing all imaging sensors to be calibrated prior to use of the imaging sensors.

[0136] Figure 10 A flowchart of a technique for determining the relative positioning of two structures at a wafer station using an auto-calibration wafer is shown. Figure 10 The technique begins at block 1002, where an auto-calibration wafer is retrieved from a docking station or other containment area for storing the auto-calibration wafer using a wafer handling robot of a semiconductor processing tool. At block 1004, a wafer station of the semiconductor processing tool for calibration may be selected. Assuming that the structures for which relative positioning is to be determined are already located in the selected wafer station, for example, the selected wafer station may have, for example, an edge ring (a first structure) placed on a wafer support (a second structure).

[0137] In block 1006, the wafer handling robot can be actuated to position the auto-calibration wafer above the wafer support of the selected wafer station. The wafer handling robot can be positioned, for example, such that the auto-calibration wafer is nominally centered above the wafer support / edge ring of the selected wafer station, thereby positioning the first camera sensor positioned along the outer circumference of the auto-calibration wafer above the edge ring and the wafer support in a manner that enables the first camera sensor to obtain an image of two fiducials (such as the inner edge of the edge ring and the edge of a feature of the wafer support, e.g., the outer edge of the ESC of the wafer support). In block 1008, the auto-calibration wafer can be caused to obtain such an image. In block 1010, the image can be analyzed to determine, for example, the gap size between the fiducials in each image. For example, an edge-finding algorithm can be used to identify the inner edge of the edge ring and the edge of the wafer support in each image and the relative distances of the gaps between each pair of the determined edges. The gap between each pair of the determined edges can be estimated based on an assumed vertical distance between the first camera sensor and the imaged structures; such estimates may be somewhat inaccurate but will generally have a similar ratio in each image. In the case where the fiducials of each structure are arranged along a common reference circle, for example, the arcuate outer edges or arcuate inner edges (or a single circular edge) of the edge ring that are all co-radial with each other can be used as the fiducial of the edge ring, and the arcuate edges (or a single circular edge) of the wafer support that are all co-radial with each other can be used as the fiducial of the wafer support. It should be understood that other fiducials with similar effects can be used, and the techniques discussed herein can generally be applied to any suitable fiducial and to algorithms for determining the relative offset between such structures based on the selected fiducial.

[0138] In block 1010, based on the gap size between the imaging fiducials of the two structures, the offset between the reference points (such as the centers of the two structures) is determined. Such an offset can be compared with an offset threshold to determine whether the eccentricity of the two structures falls within an acceptable limit. Such a deviation threshold can be established based on the non-uniformity requirements of a particular semiconductor processing technology. If the measured value of the eccentricity does not fall within the acceptable limit, appropriate actions can be taken. For example, one of the structures can be repositioned based on the measured center offset and the procedure can be repeated until the measured value of the eccentricity falls within the acceptable limit.

[0139] Figure 11Displays a flowchart of a technique for determining the position of the center point of a wafer support using an auto-calibration wafer. In block 1102, an auto-calibration wafer can be retrieved using the end effector of a wafer handling robot. In block 1104, the position of the auto-calibration wafer relative to the end effector of the wafer handling robot can be determined. In some cases, blocks 1102 and 1104 are carried out in sequence. For example, the wafer handling robot can be controlled so that the end effector picks up the auto-calibration wafer (as discussed previously), centers the auto-calibration wafer on the reference point of the end effector, and thereby determines the position of the auto-calibration wafer relative to the end effector.

[0140] In block 1106, a wafer station can be selected to determine the center point of its wafer support. In block 1108, the wafer handling robot can be actuated to position the auto-calibration wafer above the wafer support of the selected wafer station, for example, at the default center position associated with that wafer station.

[0141] In block 1110, image data of one or more fiducials, such as the wafer support, can be obtained using one or more camera sensors of the auto-calibration wafer. Such fiducials can be, for example, an etched pattern located at the center of the wafer support. Alternatively, the fiducial can be the circular edge of a portion of the wafer support, such as the circular edge of the ESC that is part of the wafer support and defines the center point of the wafer support. In the former case, a camera sensor located near or at the center of the auto-calibration wafer can be used to image the fiducial. In the latter case, a camera sensor near the outer edge of the auto-calibration wafer can be used to image the fiducial.

[0142] In block 1112, the image data can be analyzed to determine the offset between a reference point, such as the center point of the auto-calibration wafer, and the reference point of the selected wafer station defined by the fiducial. In block 1114, the offset determined in block 1112 can be converted into the coordinate system of the wafer handling robot. If necessary, the "default" position corresponding to the center point of the selected wafer support can be updated to account for the offset determined in block 1114 (alternatively, the original default position can be left and adjusted based on the offset for each subsequent wafer placement at that wafer station). In some implementations, the wafer handling robot can then be actuated to move the auto-calibration wafer so that the center of the auto-calibration wafer is positioned at the updated center position of the wafer support (similar to block 1108). In such an implementation, if necessary, blocks 1110 to 1114 can be repeated to verify that the updated centered position is properly centered. If it is found that the updated default position (or correction to the default position) still results in a center-to-center offset that does not fall within an acceptable limit, the process can be repeated one or more times.

[0143] While the above discussion has focused on using an auto - calibration wafer to determine the absolute position of the center of a wafer support or other structure relative to the coordinate system used by a wafer handling robot, as will also be discussed below, an auto - calibration wafer can also be used to determine the relative positioning between two components.

[0144] Figure 12 A flowchart of a technique showing the placement of a calibration edge ring on a wafer support is shown. In block 1202, the wafer handling robot of a semiconductor processing tool can be actuated to cause the wafer handling robot to retrieve an edge ring from a wafer station. In block 1204, the wafer handling robot can also be actuated to cause the edge ring to be placed on a wafer support, such as a pedestal, of a selected wafer station of the semiconductor processing tool. Since the edge ring may have been manually placed or mounted on the wafer support, or may have been placed or mounted on the wafer support during another phase of an operation, for example, blocks 1202 and 1204 can be optional.

[0145] In block 1206, the wafer handling robot can be controlled to cause the wafer handling robot to retrieve an auto - calibration wafer from a docking station or other location. In block 1208, the wafer handling robot can also be actuated to cause the auto - calibration wafer to be positioned above a wafer support (and an edge ring positioned thereon) of a selected wafer station.

[0146] Once the auto - calibration wafer is positioned above the wafer support of the selected wafer station, in block 1210, an edge camera of the auto - calibration wafer, such as a first imaging sensor, can be used to cause the auto - calibration wafer to obtain image data of the gap between the inner edge of the edge ring and the outer edge (or other reference) of a feature of the wafer support, such as the outer edge of an ESC that is part of the wafer support.

[0147] In block 1212, an estimated offset between the center of the edge ring and the center of the wafer support can be determined based on the relative dimensions of the gap between the image - based references. In block 1214, it can be determined whether the estimated edge ring / wafer support offset exceeds a predetermined offset threshold. If the estimated edge ring / wafer support deviation does exceed the predetermined offset threshold, the technique can proceed to block 1216, where the wafer handling robot can be actuated to remove the auto - calibration wafer from a position above the wafer support and return the auto - calibration wafer to, for example, a docking station (or some other temporary holding location). Then in block 1218, the wafer handling robot can be actuated to retrieve the edge ring from the wafer support of the selected wafer station. For example, lift pins can be used to lift the edge ring off the wafer support so that the end - effector of the wafer handling robot can be inserted under the edge ring, and then the edge ring can be lowered onto the end - effector by retracting the lift pins into the wafer support.

[0148] After the edge ring has been retrieved from the wafer support by the wafer handling manipulator in block 1218, the wafer handling manipulator can also be controlled to reposition the edge ring onto the wafer support such that the center of the edge ring is placed at a new position indicative of the edge ring offset, thereby enabling the edge ring and the wafer support to be more accurately centered with respect to each other. After block 1218, the technique can return to block 1206 and a further assessment of the center offset of the edge ring / wafer support can be obtained. If necessary, this portion of the technique can be repeated a threshold number of times, or until the estimated center offset between the edge ring and the wafer support falls within a predetermined offset threshold. If it is found in block 1214 that the estimated edge ring / wafer support offset falls within the predetermined deviation threshold, the technique can proceed to block 1222, where the edge ring placement calibration can be considered complete.

[0149] It should be understood that using an auto-calibration wafer to evaluate the relative offset between two structures can be done without the need or knowledge of accurately positioning the auto-calibration wafer relative to the end effector of the wafer handling manipulator. In particular, the techniques discussed herein can be used when the auto-calibration wafer is sufficiently centered on the end effector such that the field of view of the first imaging sensor of the auto-calibration wafer enables imaging of the various gaps between the fiducials of the two structures. It should also be understood that similar techniques can be used to center other components relative to the wafer support, such as centering a calibration wafer relative to the wafer support.

[0150] For the edge ring, once the edge ring has been properly placed on the wafer support, it can generally remain in that position for a large number of wafer processing operations. However, for centering the calibration wafer, the calibration wafer only substitutes for or represents the wafer that will be placed in future operations. Thus, once the calibration wafer has been centered on a desired structure such as the wafer support or the edge ring using the auto-calibration wafer techniques discussed herein, the calibration wafer can be removed from the centered position using the wafer handling manipulator and used to teach an Active Wafer Centering (AWC) system, which can then learn the desired center point of the calibration wafer relative to the end effector for a particular wafer handling manipulator motion path; the AWC system can then be used to evaluate the future placement of a wafer on the end effector of the wafer handling manipulator to determine the offset between the center point of such a wafer and the learned center point. The wafer handling manipulator can then be actuated to place the wafer on the wafer support in a manner that takes into account the determined offset. It should be understood that although the edge ring can generally remain in a proper position for a large number of processing operations, the edge ring can still be reset occasionally; as discussed previously, similar AWC techniques can be performed during such subsequent edge ring placements to compensate for any misalignment between such an edge ring and the end effector.

[0151] The techniques discussed herein can also be used to determine the relative offset between two movable components, such as between an edge ring and a wafer. For example, Figure 13 FIG. shows a flow chart of a technique for calibrating wafer placement relative to an edge ring on a wafer support.

[0152] In block 1302, a wafer station of a semiconductor processing tool can be selected. Similar to the Figure 12 technique, in block 1304, an edge ring can be placed on the wafer support of the selected wafer station, and in block 1306, the edge ring can be centered on the wafer support using, for example, the centering technique discussed above for Figure 12 Block 1304 and 1306 can be optional; the edge ring can also be placed on the wafer support of the selected wafer station via other means such as manual placement, or the edge ring may already be on the wafer support before the selected wafer station is selected.

[0153] In block 1308, a wafer handling robot can retrieve a calibration wafer from a storage location. The calibration wafer can be, for example, an unprocessed wafer or a virtual wafer having the same size and thickness as the wafer to be processed. In block 1310, the wafer handling robot can transfer the calibration wafer to the wafer support of the selected wafer station such that the center of the calibration wafer is formally centered on the center of the edge ring.

[0154] In block 1312, the wafer handling robot can be controlled to retrieve an auto-calibration wafer from a storage location accessible to the wafer handling robot, such as a docking station or other location. In block 1314, the wafer handling robot can be controlled to position the auto-calibration wafer above the wafer support of the selected wafer station such that the auto-calibration wafer is generally centered above the center point of the calibration wafer and / or the edge ring. In block 1316, the auto-calibration wafer can be controlled such that an edge camera of the auto-calibration wafer, such as a first imaging sensor, obtains image data of the gap between the edge ring and the calibration wafer.

[0155] In block 1318, the image data can be analyzed to determine the wafer / edge ring offset between the inner diameter of the edge ring and the outer diameter of the calibration wafer based on the relative gap size in the image. In block 1320, it can be determined whether the wafer / edge ring offset exceeds a predetermined offset threshold; if so, the technique can proceed to block 1322, where the wafer handling robot can be actuated to return the auto-calibration wafer to the docking station (or some other temporary holding location), and then proceed to block 1324, where the wafer handling robot can be further actuated to retract the calibration wafer from the wafer support of the selected wafer station. For example, the lift pins of the wafer support can be used to lift the calibration wafer off the edge ring such that the end effector of the wafer handling robot can be positioned below the calibration wafer. Once so positioned, the lift pins can be further controlled to lower the calibration wafer onto the end effector.

[0156] In block 1326, the wafer handling robot can be actuated to relocate the calibration wafer onto the wafer support of the selected wafer station such that the center of the calibration wafer is placed at a new position taking into account the wafer / edge ring offset determined in block 1318. The technique can then return to block 1312 to begin a further auto-calibration wafer imaging operation for sizing the gap between the calibration wafer and the edge ring; this relocation and re-analysis of the alignment between the calibration wafer and the edge ring can be performed multiple times until, for example, the determined wafer / edge ring offset is below a predetermined threshold, or until a predetermined number of such repetitions have been made. In the case where it is determined in block 1320 that the wafer and the edge ring are sufficiently centered relative to each other (i.e., the determined wafer / edge ring offset falls within the predetermined threshold), the technique can proceed to block 1328, where the wafer / edge ring placement calibration can be considered complete. At this point, the calibration wafer can be removed from the wafer station using the wafer handling robot and the calibration wafer can be used to train, for example, an active wafer centering system - in a very similar manner to how a calibration wafer is manually centered relative to the wafer support via fixtures or other mechanical centering systems. Training an active wafer centering system based on a centered wafer or a calibrated wafer that is otherwise placed onto the end effector of the wafer handling robot is a technique known in the art and is not described in depth in this disclosure for brevity.

[0157] It should be understood that the above technique can be implemented in various different ways to achieve similar results. For example, in a tool having multiple wafer handling robots or a wafer handling robot comprising dual arms / end effectors, one wafer handling robot arm / end effector can be used to place or reposition an object such as a calibration wafer and / or an edge ring onto the wafer support, while another wafer handling robot arm / end effector can be used to hold the auto-calibration wafer. Thus, for example, a first arm can be used to place the edge ring onto the wafer support and then retracted; then a second arm can move the auto-calibration wafer above the already placed edge ring to obtain a measurement of the center-to-center offset between the edge ring and the wafer support. The second arm can then be retracted, and if necessary, the edge ring can be lifted off the wafer support via, for example, lift pins, and the first arm can be used to reposition the edge ring to correct the center-to-center offset between the edge ring and the wafer support. The first arm can then be retracted, and the second arm can again move the auto-calibration wafer above the edge ring and the wafer support to obtain a second measurement of the center-to-center offset; this process can be repeated as needed until the desired amount of center-to-center offset between the edge ring and the wafer support is achieved.

[0158] It should also be understood that the placement of the wafer and / or edge ring on the wafer support guided by the auto-calibration wafer can be a repetitive process, in which an estimate of the relative offset between two structures such as the wafer and the wafer support, the edge ring and the wafer support, or the edge ring and the wafer can be obtained using the auto-calibration wafer, and then the estimate is used to guide the re-placement of one of the two structures relative to the other structure that can be fixed. Generally, such auto-calibration wafer-assisted placement and evaluation can be repeated until the measured offset falls within the predetermined maximum allowable offset of a given set of components of a given semiconductor processing tool. In some cases where both the edge ring and the calibration wafer are centered using the auto-calibration wafer, the relative center offset between any pair of components that are not directly centered with respect to each other among the three components (edge ring, wafer support, and calibration wafer) is further evaluated. For example, if the edge ring is centered with respect to the wafer support and the calibration wafer is centered with respect to the edge ring, the calibration wafer is not directly centered with respect to the wafer support (but only indirectly centered through the edge ring). In such an implementation, the auto-calibration wafer can be used to additionally evaluate the centering degree of the calibration wafer with respect to the wafer support. In some such implementations, a predetermined offset threshold for each pair of structures can be selected such that two of the three center-to-center offsets can fall within their respective predetermined offset thresholds, but the third center-to-center offset can actually exceed its respective predetermined offset (of course, the predetermined offset threshold can also be selected such that this does not occur, but in some cases this may allow unacceptable process uniformity in some cases, or may require some predetermined thresholds to be lower than those usually necessary, which may increase the number of centering operations that may need to be repeated). Generally, in such an implementation, in most cases, the offset threshold can usually be selected to avoid a situation where two out of three are successful / one out of three is a failure for offset threshold compliance, but if, for example, the edge ring is positioned at the limit of a predetermined edge ring / wafer support offset in a specific direction with respect to the wafer support, and the calibration wafer is positioned at the limit of a predetermined wafer / edge ring offset in the same direction with respect to the edge ring, then the calibration wafer will have the maximum center-to-center offset from the wafer support, which may exceed the maximum center-to-center offset specified for the calibration wafer / wafer support.

[0159] In such an implementation, if a situation where two out of three are successful / one out of three is a failure occurs, the semiconductor processing tool can take various corrective actions. For example, in some implementations, the controller of the semiconductor processing tool can cause one or both of the calibration wafer and the edge ring to be removed by the wafer handling robot, and then re-placed using techniques similar to the techniques discussed above, but using more stringent corresponding predetermined offset thresholds for placement, for example.

[0160] It should also be understood that some semiconductor processing tools can utilize an auto-calibration wafer to perform both calibration wafer and edge ring placement / centering operations in the following manner: centering the calibration wafer and the edge ring relative to the wafer support (rather than centering the edge ring relative to the wafer support and the calibration wafer relative to the edge ring, or vice versa).

[0161] Once the calibration wafer has been centered on the wafer support or on the edge ring on the wafer support and has been used to train the active wafer centering system, the trained active wafer centering system can then be selectively tested using the auto-calibration wafer to ensure that the trained active wafer centering system can provide reliable centered wafer placement. Figure 14 A flowchart of such a technique for verifying the repeatability of wafer placement is shown ( Figure 14 the technique is expected to be implemented after the active wafer centering system has been taught); the technique assumes that the active wafer centering system has been trained using a wafer centered relative to the wafer support, but can be appropriately modified, such as training the active wafer centering system using a wafer centered relative to the edge ring.

[0162] In block 1402, a wafer station of the semiconductor processing tool can be selected; the selected wafer station will have a calibration wafer previously centered on its wafer support using the techniques discussed above, and the active wafer centering system associated with the wafer station has been trained based on the centered position of the calibration wafer. In block 1404, the wafer transfer manipulator of the semiconductor processing tool can be caused by the controller of the semiconductor processing tool to retrieve the calibration wafer from an accommodation station of the semiconductor processing tool, such as a buffer, FOUP, or other location. In block 1406, the wafer transfer manipulator can be controlled to place the calibration wafer on the wafer support of the selected wafer station.

[0163] After placing the calibration wafer on the wafer support, in block 1408, the wafer transfer manipulator can retrieve the auto-calibration wafer from, for example, a docking station or other storage location. In block 1410, the wafer transfer manipulator can be actuated to position the auto-calibration wafer above the calibration wafer and the wafer support of the selected wafer station such that the first camera sensor of each auto-calibration wafer has the edge of the calibration wafer and the edge of the wafer support within its field of view.

[0164] In block 1412, image data of the gap between the edge of the calibration wafer and the edge of the wafer support can be obtained for the automated calibration wafer, and in block 1414, a determination can be made regarding the deviation between the center of the wafer support and the center of the calibration wafer; the offset can be stored for subsequent reference. In block 1416, the count X can be incremented to X + 1, and in block 1418, it can be determined whether X exceeds a predetermined threshold Y. X can represent the number of test placements that have been made as part of the technique, and Y can represent the total number of test placements to be made as part of the technique.

[0165] If it is determined in block 1418 that X is not greater than Y, the technique can proceed to block 1420 before returning to block 1404. In block 1420, before the wafer handling robot returns to the default or "home" position in block 1422, the calibration wafer can return to its original position in the holding station, or to another position with a randomized offset. The randomized offset can be selected such that it falls within the typical expected offsets of wafers under normal operating use, for example, an offset less than 0.8 mm. Thus, when the wafer handling robot retrieves the calibration wafer again in block 1404 (which would typically result in returning to the same position each time to retrieve the calibration wafer), the calibration wafer will have a corresponding randomized offset position relative to the end effector of the wafer handling robot. It should also be understood that wafer placement randomization can occur at other times, such as just before retrieving the calibration wafer from the holding station or other location, such that the wafer handling robot experiences a randomized placement to similarly randomize the position of the calibration wafer relative to the end effector. Such randomization can be used to represent the slight misalignment of wafers placed in the holding station during normal operation.

[0166] If it is determined in block 1418 that a sufficient number of test wafer placements have been made, the technique can proceed to block 1424, where the center offsets of the Y wafer placements can be evaluated or analyzed. Such an analysis can include any of a variety of different analysis techniques or tests, for example, statistical parameters of the captured group of test wafer offsets can be determined and compared to corresponding thresholds. For example, the mean, median, and standard deviation of the offsets can be determined and compared to the corresponding thresholds for such values to determine whether the wafer placements obtained from the test technique have acceptable consistency. In block 1426, the offsets can be compared to these thresholds (or more precisely, the statistical parameters derived from the offsets can be compared to their corresponding thresholds) to determine whether the test was successful. If the comparison in block 1426 indicates that one or more of the allowed parameters have been exceeded, the technique can proceed to block 1428, where an error condition can be generated. If the comparison in block 1426 indicates that one or more of the parameters fall within the acceptable limits, the technique can proceed to block 1430, where the technique can be successfully completed.

[0167] It should be understood that similar techniques can also be implemented using an edge ring, such as performing repeated edge ring placement and randomizing the end effector / edge ring offset between each placement to evaluate the repeatability of edge ring placement.

[0168] Figure 15 A flowchart of a technique for evaluating the height of an edge ring is shown. In block 1502, a wafer stage of a semiconductor processing tool can be selected; the selected wafer stage should already have an edge ring located on its wafer support. For example, an edge ring in a suitable position remaining on the wafer support during a processing operation can be utilized, and during such an operation, at regular intervals, Figure 15 a technique can be performed to determine whether the edge ring has degraded in a non-uniform manner (or, regardless of uniformity, to an unacceptable degree) due to exposure to repeated semiconductor wafer processing cycles.

[0169] In block 1504, an auto-calibration wafer can be retrieved with a wafer transfer robot and then transferred to the wafer support of the selected wafer stage. Such transfer of the auto-calibration wafer to the wafer support can include, for example, lifting the calibration wafer off the wafer transfer robot by lift pins and then lowering the auto-calibration wafer onto the edge ring by retracting the lift pins, placing the auto-calibration wafer directly onto the edge ring.

[0170] In block 1508, a proximity sensor of the auto-calibration wafer can be utilized to obtain a distance measurement between the auto-calibration wafer and the wafer support. In some implementations, such distance measurements can typically be obtained using proximity sensors at at least three positions near the circumference of the auto-calibration wafer, whereby the orientation of the plane defined by the auto-calibration wafer relative to the plane defined by the upper surface of the wafer support can be determined; if the distance between the two planes at any point near a circle centered on the diameter of the edge ring at or near the inner diameter of the edge ring exceeds a specific threshold, this can indicate that the thickness of the edge ring is out of tolerance and the edge ring should be replaced.

[0171] In block 1510, an auto-calibration wafer can be removed from a wafer support using a wafer transfer robot. In block 1512, the obtained distance measurements can be evaluated and it can be determined whether the measured distance indicates that the edge ring falls within an acceptable height limit. For example, if any of the proximity distances is below (or above) a predetermined threshold, this can indicate that the edge ring height is too small (or too large). Another metric that can be used to evaluate the edge ring height is the difference between different distance measurements. For example, for a given measurement cycle using an auto-calibration wafer, the difference between the maximum distance measurement and the minimum distance measurement of the edge ring can be compared to another predetermined threshold to determine whether the edge ring height near the circumference of the edge ring varies by an unacceptable amount. If it is determined in block 1512 that the distance measurements fall within acceptable bounds, the technique can proceed to block 1516, where a success condition can be determined. If it is determined in block 1512 that the distance measurements do not fall within acceptable limits, the technique can proceed to block 1514, where a failure or error condition can be generated. Such a condition can cause the semiconductor processing tool to stop further processing operations at the wafer station until a new edge ring has been installed, centered, and height measured.

[0172] As previously described, in some implementations, an auto-calibration wafer can be used to determine the dynamic characteristics of a semiconductor processing tool, such as the vibration and tilt of lift pins. Figure 16 A flowchart showing a technique for evaluating lift pin vibration is shown.

[0173] Figure 16 The technique can begin at block 1602, where a wafer station for lift pin vibration evaluation can be selected. In block 1604, the wafer transfer robot can be actuated to retrieve an auto-calibration wafer from a storage location, such as a docking station. In block 1606, the auto-calibration wafer can be positioned above the wafer support of the selected wafer station, and then the lift pins of the wafer support can be caused to lift the auto-calibration wafer off the end effector of the wafer transfer robot. In block 1608, the auto-calibration wafer can be caused to begin obtaining vibration data from the vibration sensors of the auto-calibration wafer; it should be understood that in some implementations, such data can also be obtained earlier or continuously. In block 1610, the lift pins can be actuated to move the auto-calibration wafer vertically, for example, relative to the wafer support. In some implementations, such movement can include lowering the auto-calibration wafer onto the wafer support and then lifting it again, as a semiconductor wafer would typically experience during a normal wafer placement operation. In other implementations, the lift pins can be actuated in a manner that does not correspond to a normal wafer placement movement, but is designed to more readily cause a particular vibration response. In either case, the auto-calibration wafer is exposed to movement by actuating the lift pins, and vibration data can be collected through one or more vibration sensors during such movement.

[0174] In block 1612, the wafer transfer robot can be controlled to retrieve the auto-calibration wafer from the lift pins, and in block 1614, the vibration data can be analyzed to determine if it falls within acceptable limits. For example, if the amplitude of the vibration exceeds a predetermined threshold, or if the magnitude of a particular frequency component of the vibration exceeds a predetermined threshold, it can be determined that the vibration measurement is outside the acceptable limits, and the technique can proceed to block 1618, where an error condition is generated. The duration of the lift pin movement during each stage of movement can also be measured and compared to an acceptable range to determine if there is an error condition in the lift pin mechanism. In such a case, the semiconductor processing tool can, for example, suspend the wafer processing operation at the wafer processing station until the lift pin mechanism has been serviced and the problem resolved. If the lift pin mechanism is controlled by an actuator, a closed-loop system can be implemented to automatically calibrate the lift pin mechanism using the vibration data. In some implementations, the semiconductor processing tool can generate a warning indicating that the lift pin mechanism needs maintenance or repair, but can continue the semiconductor processing operation at the wafer station (and using the lift pin mechanism) until a subsequent vibration assessment of the lift pins indicates that the vibration occurring during lift pin actuation has exceeded a second set of acceptable limits. In some such implementations, after encountering an error condition, the semiconductor processing tool can operate the lift pin mechanism at a lower performance level (e.g., at a lower speed compared to the normal lift pin mechanism speed) in order to potentially reduce the amplitude of the vibration experienced. Such a lower throughput operation can be continued until the lift pin mechanism has been repaired and the problem resolved, or until the vibration generated during the operation of the lift pin mechanism has degraded to a further unacceptable level, in which case the use of the wafer station and the lift pin mechanism can be suspended until maintenance can be performed. The vibration data of the lift pin mechanism can be sent to a data center outside the tool that has big data and machine learning capabilities, and the data center can receive vibration data from a large number of similar semiconductor processing tools to establish healthy versus unhealthy lift pin vibration identification features. In such a case, the raw vibration data or the vibration identification features (after machine learning feature extraction) can be sent to the data center. The data center can use the received vibration data of the batch semiconductor processing tools to train a machine learning model, such as a neural network, tensor flow, etc., to classify the lift pin mechanism as healthy or unhealthy.

[0175] Another test technique that can be performed with the auto-calibration wafer is to evaluate the levelness of the wafer support (or other facilities, such as the end effector of the wafer transfer robot, the lift pin mechanism, the load port module (LPM), the wafer support, the ESC, etc.). Figure 17 A flowchart of a technique for evaluating the levelness of the wafer support is shown, but the technique can be implemented for various different wafer transfer components.

[0176] In block 1702, a wafer station of a semiconductor processing tool for the measurement of the flatness of a wafer support can be selected.

[0177] In block 1704, a wafer handling robot of the semiconductor processing can retrieve an auto-calibration wafer from a docking station or other storage location, and in block 1706, the wafer handling robot can be controlled to place the auto-calibration wafer directly onto the wafer support. If an edge ring already exists on the wafer support and would interfere with the direct placement of the auto-calibration wafer onto the wafer support, the edge ring can be removed by the wafer handling robot of the semiconductor processing tool before placing the auto-calibration wafer onto the wafer support.

[0178] Once the auto-calibration wafer is placed onto the wafer support, in block 1708, an orientation sensor (such as an accelerometer or a tilt sensor) can be used to obtain a flatness measurement of the auto-calibration wafer. In some implementations, multiple flatness sensors can be used to obtain such a measurement.

[0179] In block 1710, the auto-calibration wafer can be retrieved from the wafer support by the wafer handling robot, and in block 1712, it can be determined whether the flatness measurement of the wafer support falls within acceptable limits. If not, the technique can proceed to block 1714, where an error condition can be generated. If so, the technique can proceed to block 1716, where a success condition can be generated.

[0180] It should be understood that the various techniques described herein can be combined in various ways to provide a fully automated system for configuring a semiconductor processing tool. For example, the semiconductor processing tool can be configured to have an "initial setup" mode, which can be used for the following scenarios: the tool can retrieve an edge ring and center the edge ring on each wafer support in a semiconductor processing chamber using an auto-calibration wafer, then center the calibration wafer and the associated edge ring for each wafer support using the auto-calibration wafer, train an active wafer centering system and a wafer handling robot using the centered calibration wafer, and then verify that the trained active wafer centering system produces reliable wafer placement. The semiconductor processing tool can also periodically perform various health checks, such as checking whether the center-to-center offset of the edge ring and the calibration wafer has drifted to an unacceptable distance, checking whether the edge ring height still falls within an acceptable range after a predetermined time period or number of wafer processing operations, and / or checking whether the wafer support is level and / or whether the lift pin vibration falls within an acceptable range.

[0181] As described above, the controller can be part of a system that can include a semiconductor processing apparatus, which includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestal, gas flow system, etc.). These systems can be integrated with electronics for controlling their operations before, during, and after the processing of semiconductor wafers or substrates. The electronics can be referred to as a "controller", which can control various components or sub-components of one or more systems. Depending on the processing requirements and / or the type of system, the controller can be programmed to control any of the processes disclosed herein, as well as various parameters affecting semiconductor processing, such as the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, wafer transfer in and out of tools and other transfer tools, and / or load locks connected or interfaced with a particular system.

[0182] Broadly speaking, the controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software for receiving instructions, issuing instructions, controlling operations, enabling cleaning operations, enabling endpoint measurements, etc. The integrated circuits can include chips in the form of firmware storing program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). The program instructions can be instructions sent to the controller in the form of various individual settings (or program files), which define the operating parameters for performing a specific process on or with respect to a semiconductor wafer or system. In some embodiments, the operating parameters can be part of a recipe defined by a process engineer to complete one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or die of a wafer.

[0183] In some implementations, the controller can be part of or coupled to a computer that is integrated with, coupled to, networked to the system in other ways, or a combination thereof. For example, the controller can be in the "cloud" or be all or part of a fab host system, which can allow remote access to wafer processing. The computer can implement remote access to the system to monitor the current progress of manufacturing operations, review the history of past manufacturing operations, review trends or performance criteria of multiple manufacturing operations, change the parameters of the current process, set process steps to follow the current process, or initiate a new process. In some examples, a remote computer (such as a server) can provide a process recipe to the system via a network, which can include a local network or the Internet. The remote computer can include a user interface that enables the input or programming of parameters and / or settings, which are then sent from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify the parameters for each process step to be performed during one or more operations. It should be understood that the parameters can be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller can be distributed, for example, by including one or more discrete controllers that are networked together and work towards a common purpose (such as the processes and controls described herein). An example of a distributed controller for such a purpose is one or more integrated circuits on a chamber that communicate with one or more integrated circuits remote (such as at the platform level or as part of a remote computer), which combine to control the process on the chamber.

[0184] Exemplary systems can include, but are not limited to, plasma etch chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing system that can be associated with or used in the manufacture and / or preparation of semiconductor wafers.

[0185] As described above, depending on one or more process steps to be performed by the tool, the controller can communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the factory, a host computer, another controller, or tools used in the material transport that shuttles wafer containers to and from tool locations and / or load ports in a semiconductor manufacturing facility.

[0186] It should be understood that although the above discussion focuses on an automatic calibration wafer system that typically features multiple camera sensors (with one or more additional sensors in various other implementations), some implementations may feature a single camera sensor mounted at the center and no camera sensors at the edges, or only camera sensors at the edges and no camera sensor mounted at the center; in some cases, the corresponding functionality provided by such implementations may be less than that of an implementation with both a camera sensor mounted at the center and a camera sensor mounted at the edges, but this is not necessarily the case. The present disclosure should also be understood to encompass such alternative implementations.

[0187] As used herein, the term "wafer" may refer to a semiconductor wafer or substrate or other similar type of wafer or substrate. As used herein, a wafer station may refer to any location in a semiconductor processing tool where a wafer may be placed during any one of a variety of wafer processing operations or wafer transfer operations. A wafer support is used herein to refer to any structure in a wafer station configured to receive and support a semiconductor wafer, such as a pedestal, an electrostatic chuck, a wafer support frame, etc.

[0188] As used herein, the term "nominal centering" refers to the relative placement of two or more objects such that some locations, such as a center point or similar location, are generally aligned with each other in the XY plane. Such alignment may not be ideal for various reasons, such as the sliding of one of the objects, sensor drift, etc., but in most cases, the nominally centered objects may differ from the ideally centered objects by within one or two millimeters.

[0189] It should also be understood that the use of ordinal numbers herein, such as (a), (b), (c),..., is for organizational purposes only and is not intended to convey any particular order or importance to the items associated with each ordinal number. For example, "(a) obtaining information related to speed; and (b) obtaining information related to position" should encompass obtaining information related to position before obtaining information related to speed, obtaining information related to speed before obtaining information related to position, and obtaining information related to speed while obtaining information related to position. Nevertheless, there may be cases where certain items associated with ordinal numbers may inherently require a particular order. For example, "(a) obtaining information about speed, (b) determining acceleration based on the information about speed, and (c) obtaining information about position"; in this example, (a) needs to be performed before (b) because (b) depends on the information obtained in (a), whereas (c) may be performed before or after either (a) or (b).

[0190] It should be understood that, for example, phrases such as "for each of the one or more <items>" or "of each <item>"<item>) The use of the term "each" (if used in this text) shall be understood to include both single-item groups and multiple-item groups, that is, the use of the phrase "for... each" means that in programming languages it is used to refer to each item in the entire group of items being referred to. For example, if the group of items being referred to is a single item, "each" will refer only to that single item (even though the dictionary definition of "each" often defines it as referring to "each of two or more things"), and it does not mean that there must be at least two of these items. Similarly, when the selected item can have one or more sub-items and a selection is made of one of these sub-items, it should be understood that in the case where the selected item has one and only one sub-item, selecting that one sub-item is inherently selecting the item itself.

[0191] It should also be understood that the reference to multiple controllers that are generally configured to perform multiple functions is intended to cover both the case where only one of these controllers is configured to perform all of the functions disclosed or discussed, and the case where each of the various controllers performs a sub-part of the functions discussed. For example, an auto-calibration wafer may include a controller that is configured to: control the operation of various sensors on the auto-calibration wafer and communicate data from the sensors to another controller associated with a semiconductor processing tool; and then the semiconductor processing tool controller may analyze such data to determine various operating parameters for use with the semiconductor processing tool.

[0192] Various modifications to the embodiments described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of this disclosure. Accordingly, the claims are not intended to be limited to the embodiments presented herein, but should be accorded the broadest scope consistent with the disclosure, principles, and novel features disclosed herein.

[0193] Certain features described in this specification in the context of separate implementations may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. Additionally, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from the claimed combination may in some cases be deleted from that combination, and the claimed combination may be directed to a sub-combination or variations of the sub-combination.

[0194] Similarly, although the operations are depicted in a particular order in the figures, this should not be construed as requiring that the operations be performed in the particular order shown or in a sequential order, or that all of the illustrated operations be performed to achieve the desired result. Additionally, the figures may schematically depict another example process in the form of a flowchart. However, other operations not depicted may be incorporated into the example process schematically shown. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some cases, multitasking and parallel processing may be advantageous. Further, the separation of various system components in the above-described embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the program components and systems may generally be integrated together in a single software product or encapsulated into multiple software products. Additionally, other embodiments fall within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result.< / item>

Claims

1. A system for semiconductor processing, comprising: a semiconductor processing tool, which includes: a wafer transfer robot; one or more wafer stations; and a second controller, wherein: each wafer station has one or more corresponding wafer supports, and the wafer transfer robot is communicatively connected to the second controller; and an auto - calibration wafer, which includes: a substrate, the size of which is set to be transported by the wafer transfer robot and has a first side, and the first side is configured to contact the end - effector of the wafer transfer robot when the substrate is transported by the wafer transfer robot; a plurality of first camera sensors, which are supported by the substrate and located at a plurality of positions offset from a common point of the substrate. When the substrate is positioned with the first side facing down and placed above the wafer support, each of the first camera sensors has a downward - facing field of view and is configured to acquire images of at least two of the following: a) a reference related to the wafer support, b) a semiconductor wafer placed on the wafer support, c) an edge ring placed on the wafer support; and a first controller, wherein the first controller is communicatively connected to each of the first camera sensors, and the second controller and the first controller are jointly configured to: a) select a first wafer support from the one or more wafer supports of a first wafer station among the one or more wafer stations; b) cause the wafer transfer robot to position the auto - calibration wafer above the first wafer support; c) cause each first camera sensor to obtain a corresponding first image of the reference of the first wafer support when the auto - calibration wafer is positioned above the first wafer support; d) determine the position information of the center point of the first wafer support based on the first image; e) cause the wafer transfer robot to retrieve the calibration wafer, f) cause the wafer transfer robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer is nominally centered on the center point of the first wafer support when viewed along a vertical axis; g) cause the wafer transfer robot to position the auto - calibration wafer above the first wafer support and the calibration wafer; h) cause each first camera sensor to obtain a corresponding second image of the reference of the first wafer support and the reference of the calibration wafer when the auto - calibration wafer is positioned above the first wafer support and the calibration wafer; and i) judge the horizontal offset of the wafer / wafer support between the center point of the calibration wafer and the center point of the first wafer support based on the gap size between the reference of the first wafer support and the reference of the calibration wafer in the second image.

2. The system according to claim 1, wherein: the auto - calibration wafer further includes a rechargeable battery configured to supply power to at least the first controller and the first camera sensors; and the auto - calibration wafer further includes a wireless charging feature configured to charge the rechargeable battery when the rechargeable battery is docked with an electromagnetic field.

3. The system according to claim 1, wherein: the automatic calibration wafer further comprises a first wireless communication interface, the first wireless communication interface includes one or more wireless communication interfaces selected from a Bluetooth transceiver and a WiFi transceiver, the first wireless communication interface is communicatively connected to the first controller.

4. The system according to claim 1, wherein: the automatic calibration wafer further comprises one or more orientation sensors, each orientation sensor is selected from the group consisting of an inclinometer and an accelerometer, and the one or more orientation sensors are communicatively connected to the first controller.

5. The system according to claim 1, wherein: the automatic calibration wafer further comprises one or more vibration sensors, each vibration sensor is selected from the group consisting of an accelerometer, a laser microphone, and an optical distance measurement sensor, and the one or more vibration sensors are communicatively connected to the first controller.

6. The system according to claim 1, wherein: the automatic calibration wafer further comprises one or more proximity sensors, each proximity sensor being configured to measure the distance between the first side and an object located below the proximity sensor when the first side faces downward, each proximity sensor is selected from the group consisting of an optical proximity sensor, an inductive proximity sensor, and a capacitive proximity sensor, and the one or more proximity sensors are communicatively connected to the first controller.

7. The system according to claim 1, wherein: the first camera sensor is arranged in a circular array around the common point, the substrate is nominally circular and has the same diameter as the semiconductor wafer configured for the semiconductor processing tool to process, the substrate is a nominally circular disc, and the disc has a diameter selected from the group consisting of 200 mm, 300 mm, and 450 mm, and the automatic calibration wafer further comprises: a rechargeable battery configured to supply power to at least the first controller and the first camera sensor; a wireless charging feature configured to charge the rechargeable battery when the rechargeable battery docks with an electromagnetic field; a first wireless communication interface communicatively connected to the first controller and including one or more wireless communication interfaces selected from the group consisting of a Bluetooth transceiver and a WiFi transceiver; one or more vibration sensors communicatively connected to the first controller; and one or more proximity sensors, each proximity sensor communicatively connected to the first controller and configured to measure the distance between the first side and an object located below the proximity sensor when the first side faces downward.

8. The system according to claim 1, wherein the first controller and the second controller are further jointly configured to: j) compare the horizontal offset of the wafer / wafer support with a horizontal offset threshold of the wafer / wafer support; and k) in response to determining that the horizontal offset of the wafer / wafer support is higher than the horizontal offset threshold of the wafer / wafer support, cause the wafer handling robot to reposition the calibration wafer relative to the first wafer support to reduce the horizontal offset of the wafer / wafer support.

9. The system according to any one of claims 1 - 7, wherein the first controller and the second controller are further jointly configured to: j) cause the wafer handling robot to retrieve a first edge ring; and k) cause the wafer handling robot to transfer the first edge ring to the first wafer support such that the center point of the first edge ring is nominally centered on the center point of the first wafer support when viewed along the vertical axis; l) cause the wafer handling robot to position the auto - calibration wafer above the first wafer support and the first edge ring; m) cause each first camera sensor to obtain a corresponding third image of the reference of the first wafer support and the reference of the first edge ring when the auto - calibration wafer is positioned above the first wafer support and the first edge ring; and n) determine a horizontal offset of the edge ring / wafer support between the center point of the first edge ring and the center point of the first wafer support based on a gap size between the reference of the first wafer support and the reference of the first edge ring in the third image.

10. The system according to claim 9, wherein the first controller and the second controller are further jointly configured to: o) compare the horizontal offset of the edge ring / wafer support with a horizontal offset threshold of the edge ring / wafer support; and p) in response to determining that the horizontal offset of the edge ring / wafer support is higher than the horizontal offset threshold of the edge ring / wafer support, cause the wafer handling robot to re - position the first edge ring relative to the first wafer support to reduce the horizontal offset of the edge ring / wafer support.

11. The system according to claim 9, wherein the second controller and the first controller are further jointly configured to: o) cause the wafer handling robot to retrieve a calibration wafer; p) cause the wafer handling robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer is nominally centered on the center point of the first edge ring when viewed along the vertical axis, q) cause the wafer handling robot to position the auto - calibration wafer above the first wafer support, the first edge ring, and the calibration wafer; r) cause each first camera sensor to obtain a corresponding fourth image of the reference of the calibration wafer and the reference of the first edge ring when the auto - calibration wafer is positioned above the first wafer support, the calibration wafer, and the first edge ring ； and s) determine a horizontal offset of the edge ring / wafer between the center point of the first edge ring and the center point of the calibration wafer based on a gap size between the reference of the calibration wafer and the reference of the first edge ring in the fourth image, t) compare the horizontal offset of the edge ring / wafer with a horizontal offset threshold of the edge ring / wafer; and u) In response to determining that the horizontal offset of the edge ring / wafers is higher than the horizontal offset threshold of the edge ring / wafers, cause the wafer handling robot to reposition the calibration wafer relative to the first edge ring to reduce the horizontal offset of the edge ring / wafers.

12. The system according to claim 4, wherein the first controller and the second controller are jointly configured to: j) Cause the wafer handling robot to transfer the auto-calibration wafer to the first wafer station; and k) Cause the one or more orientation sensors to obtain an inclination measurement of the substrate.

13. The system according to claim 5, wherein The first wafer support includes a plurality of lift pins, and The first controller and the second controller are jointly configured to: j) Cause a relative displacement between the lift pins and the first wafer support so that the lift pins protrude from the first wafer support; k) Cause the wafer handling robot to transfer the auto-calibration wafer to the lift pins; l) When the auto-calibration wafer is supported by the lift pins, cause a further relative displacement between the lift pins and the first wafer support; m) Obtain vibration data from the one or more vibration sensors during (l); n) Evaluate the vibration data to determine whether the vibration data indicates that the vibration exceeds a predetermined threshold; And o) Provide a notification when the vibration data exceeds the predetermined threshold.

14. The system according to claim 6, further comprising the semiconductor processing tool, wherein The second controller and the first controller are further jointly configured to: j) Determine that one of the one or more wafer supports in one or more wafer stations supports an edge ring; k) Cause the auto-calibration wafer to be placed on the edge ring; l) Cause each proximity sensor to measure the distance between the wafer support supporting the edge ring and the auto-calibration wafer; m) Determine one or more height measurements related to the edge ring based on the one or more distances; n) Evaluate the one or more height measurements to determine whether the height related to the edge ring exceeds a predetermined threshold; and o) Provide a notification when the height related to the edge ring exceeds the predetermined threshold.

15. A system for semiconductor processing, Comprising: A semiconductor processing tool, wherein the semiconductor processing tool includes: A wafer handling robot; One or more wafer stations; and A second controller, wherein: Each wafer station includes one or more corresponding wafer supports, and The wafer handling robot is communicatively connected to the second controller; and An auto-calibration wafer, which includes: A substrate, the size of which is set to be transported by the wafer handling robot and has a first side, the first side being configured to contact the end effector of the wafer handling robot when the substrate is transported by the wafer handling robot; A plurality of first camera sensors, which are supported by the substrate and located at a plurality of positions deviating from the common point of the substrate, and when the substrate is positioned with the first side facing down, each of the first camera sensors has a downward-facing field of view; and A first controller, wherein: The first controller is communicatively connected to each first camera sensor, and the second controller and the first controller are jointly configured to: a) select a first wafer support among the one or more wafer supports of a first wafer station in the one or more wafer stations, b) cause the wafer handling robot to retrieve a calibration wafer; c) cause the wafer handling robot to transfer a first edge ring to the first wafer support such that, when viewed along a vertical axis, a center point of the first edge ring is nominally centered on the center point of the first wafer support; d) cause the wafer handling robot to position the automatic calibration wafer above the first wafer support and the first edge ring; e) when the automatic calibration wafer is positioned above the first wafer support and the first edge ring, cause each first camera sensor to obtain a corresponding second image of a reference of the first wafer support and a reference of the first edge ring; and f) determine a horizontal offset of the edge ring / wafer support between the center point of the first edge ring and the center point of the first wafer support based on a gap size between the reference of the first wafer support and the reference of the first edge ring in the second image.

16. The system according to claim 15, wherein: the automatic calibration wafer further includes a rechargeable battery configured to supply power to at least the first controller and the first camera sensor; and the automatic calibration wafer further includes a wireless charging feature configured to charge the rechargeable battery when the rechargeable battery is docked with an electromagnetic field.

17. The system according to claim 15, wherein: the automatic calibration wafer further includes a first wireless communication interface, the first wireless communication interface includes one or more wireless communication interfaces of a Bluetooth transceiver and a WiFi transceiver, and the first wireless communication interface is communicatively connected to the first controller.

18. The system according to claim 15, wherein: the automatic calibration wafer further includes one or more orientation sensors, each orientation sensor is selected from the group consisting of an inclinometer and an accelerometer, and the one or more orientation sensors are communicatively connected to the first controller.

19. The system according to claim 15, wherein: the automatic calibration wafer further includes one or more vibration sensors, each vibration sensor is selected from the group consisting of an accelerometer, a laser microphone, and an optical distance measurement sensor, and the one or more vibration sensors are communicatively connected to the first controller.

20. The system according to claim 15, wherein: the automatic calibration wafer further includes one or more proximity sensors, each proximity sensor being configured to measure a distance between the first side and an object located below the proximity sensor when the first side faces downward, each proximity sensor is selected from the group consisting of an optical proximity sensor, an inductive proximity sensor, and a capacitive proximity sensor, and the one or more proximity sensors are communicatively connected to the first controller.

21. The system according to claim 15, wherein: The first imaging sensors are arranged in a circular array around the common point. The substrate is nominally circular and has the same diameter as a semiconductor wafer configured to be processed by the semiconductor processing tool. The substrate is a nominally circular disk, and the disk has a diameter selected from the group consisting of 200 mm, 300 mm, and 450 mm, and The automatic calibration wafer further comprises: A rechargeable battery configured to provide power to at least the first controller and the first imaging sensors. A wireless charging feature configured to charge the rechargeable battery when the rechargeable battery docks with an electromagnetic field. A first wireless communication interface communicatively coupled to the first controller and comprising one or more wireless communication interfaces selected from the group consisting of a Bluetooth transceiver and a WiFi transceiver. One or more vibration sensors communicatively coupled to the first controller; and One or more proximity sensors, each proximity sensor communicatively coupled to the first controller and configured to measure the distance between the first side and an object located below the proximity sensor when the first side is facing down.

22. The system according to any one of claims 15 - 21, wherein the first controller and the second controller are further jointly configured to: g) Cause the wafer handling robot to position the automatic calibration wafer above the first wafer support. h) Cause each first imaging sensor to obtain a corresponding first image of the reference of the first wafer support when the automatic calibration wafer is positioned above the first wafer support. i) Determine position information of the center point of the first wafer support based on the first image. j) Cause the wafer handling robot to retrieve the calibration wafer. k) Cause the wafer handling robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer is nominally centered on the center point of the first wafer support when viewed along the vertical axis. l) Cause the wafer handling robot to position the automatic calibration wafer above the first wafer support and the calibration wafer. m) Cause each first imaging sensor to obtain a corresponding third image of the reference of the first wafer support and the reference of the calibration wafer when the automatic calibration wafer is positioned above the first wafer support and the calibration wafer. n) Determine a wafer / wafersupport horizontal offset between the center point of the calibration wafer and the center point of the first wafer support based on a gap size between the reference of the first wafer support and the reference of the calibration wafer in the third image. o) Compare the wafer / wafersupport horizontal offset with a wafer / wafersupport horizontal offset threshold; and p) In response to determining that the wafer / wafersupport horizontal offset is higher than the wafer / wafersupport horizontal offset threshold, cause the wafer handling robot to reposition the calibration wafer relative to the first wafer support to reduce the wafer / wafersupport horizontal offset.

23. The system according to claim 15, wherein the first controller and the second controller are further jointly configured to: g) Compare the horizontal offset of the edge ring / wafersupport with a horizontal offset threshold of the edge ring / wafersupport; and p) In response to determining that the horizontal offset of the edge ring / wafersupport is higher than the horizontal offset threshold of the edge ring / wafersupport, cause the wafer handling robot to reposition the first edge ring relative to the first wafer support to reduce the horizontal offset of the edge ring / wafersupport.

24. The system according to claim 15, wherein the first controller and the second controller are further jointly configured to: g) Cause the wafer handling robot to retrieve a calibration wafer, h) Cause the wafer handling robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer is nominally centered on the center point of the first edge ring when viewed along a vertical axis; i) Cause the wafer handling robot to position the auto - calibration wafer above the first wafer support, the first edge ring, and the calibration wafer; j) Cause each first camera sensor to obtain a corresponding second image of the reference of the first edge ring and the reference of the calibration wafer when the auto - calibration wafer is positioned above the first wafer support, the first edge ring, and the calibration wafer; k) Determine the edge ring / wafer horizontal offset between the center point of the calibration wafer and the center point of the first edge ring based on the gap size between the calibration wafer and the reference of the first edge ring in the second image; l) Compare the edge ring / wafer horizontal offset with an edge ring / wafer horizontal offset threshold; and m) In response to determining that the edge ring / wafer horizontal offset is higher than the edge ring / wafer horizontal offset threshold, cause the wafer handling robot to reposition the calibration wafer relative to the first edge ring to reduce the edge ring / wafer horizontal offset.

25. The system according to claim 18, wherein the first controller and the second controller are jointly configured to: g) Cause the wafer handling robot to transfer the auto - calibration wafer to the first wafer station, and h) Cause the one or more orientation sensors to obtain an inclination measurement of the substrate.

26. The system according to claim 19, wherein: the first wafer support includes a plurality of lift pins, and the first controller and the second controller are jointly configured to: g) Cause relative translation between the lift pins and the first wafer support such that the lift pins protrude from the first wafer support, h) Cause the wafer handling robot to transfer the auto - calibration wafer to the lift pins, i) During the time when the auto - calibration wafer is supported by the lift pins, cause further relative translation between the lift pins and the first wafer support, j) Acquire vibration data from one or more vibration sensors during (i), k) Evaluate the vibration data to determine whether the vibration data indicates that the vibration exceeds a predetermined threshold, and l) Provide a notification when the vibration data exceeds the predetermined threshold.

27. The system according to claim 20, wherein The first controller and the second controller are jointly configured to: g) Determine a support edge ring in one or more wafer supports of one or more wafer stations, h) Place the auto - calibration wafer on the edge ring, i) Cause each proximity sensor to measure the distance between the wafer support supporting the edge ring and the auto - calibration wafer, j) Determine one or more height measurements associated with the edge ring based on one or more distances, k) Evaluate the one or more height measurements to determine whether the height associated with the edge ring exceeds a predetermined threshold, and l) Provide a notification when the height associated with the edge ring exceeds the predetermined threshold.

28. A system for semiconductor processing, the system comprising: A semiconductor processing tool, wherein the semiconductor processing tool includes: A wafer transfer robot; One or more wafer stations; and A second controller, wherein: Each wafer station includes one or more corresponding wafer supports, and The wafer transfer robot and the second controller are communicatively connected; and An auto - calibration wafer, comprising: A substrate sized to be carried by the wafer transfer robot and having a first side configured to contact the end - effector of the wafer transfer robot when the substrate is carried by the wafer transfer robot; A plurality of first camera sensors supported by the substrate and positioned at locations offset from a common point of the substrate, each first camera sensor having a downward field of view when the first side of the substrate is facing down; and One or more vibration sensors, each vibration sensor being an accelerometer, a laser microphone, or an optical ranging sensor, and a first controller, wherein: The first controller is communicatively connected to each of the first camera sensors and each of the one or more vibration sensors, and The first controller and the second controller are jointly configured to: a) Select a first wafer support among one or more wafer supports of a first wafer station among one or more wafer stations, wherein the first wafer support includes a plurality of lift pins, b) Cause relative translation between the lift pins and the first wafer support such that the lift pins protrude from the first wafer support, c) Cause the wafer transfer robot to transfer the auto - calibration wafer to the lift pins, d) Cause further relative translation between the lift pins and the first wafer support while the auto - calibration wafer is supported by the lift pins, e) Obtain vibration data from one or more vibration sensors during (d), f) Evaluate the vibration data to determine that the vibration data indicates that the vibration exceeds a predetermined threshold, and g) Provide a notification when the vibration data exceeds the predetermined threshold.

29. The system according to claim 28, wherein: The auto - calibration wafer further includes a rechargeable battery configured to provide power to at least the first controller and the first camera sensors; and The auto - calibration wafer further includes a wireless charging feature configured to charge the rechargeable battery when connected to an electromagnetic field.

30. The system according to claim 28, wherein: The auto - calibration wafer further includes a first wireless communication interface, The first wireless communication interface includes one or more wireless communication interfaces selected from the group consisting of a Bluetooth transceiver and a WiFi transceiver, and the first wireless communication interface is communicatively connected to the first controller.

31. The system according to claim 28, wherein: the automatic calibration wafer further includes one or more orientation sensors, each orientation sensor is selected from the group consisting of an inclinometer and an accelerometer, and the one or more orientation sensors are communicatively connected to the first controller.

32. The system according to claim 28, wherein: the automatic calibration wafer further includes one or more proximity sensors, each proximity sensor being configured to measure the distance between the first side and an object located below the proximity sensor when the first side is facing downwards, each proximity sensor is selected from the group consisting of an optical proximity sensor, an inductive proximity sensor, and a capacitive proximity sensor, and the one or more proximity sensors are communicatively connected to the first controller.

33. The system according to claim 28, wherein: the first camera sensors are arranged in a circular array around a common point, the substrate is nominally circular and has the same diameter as the semiconductor wafer configured to be processed by the semiconductor processing tool, the substrate is a nominally circular disc, the diameter of which is selected from the group: 200 mm, 300 mm, and 450 mm, and the automatic calibration wafer further includes: a rechargeable battery configured to supply power to at least the first controller and the first camera sensors, a wireless charging feature configured to charge the rechargeable battery when connected to an electromagnetic field, a first wireless communication interface communicatively connected to the first controller and including one or more wireless communication interfaces selected from the group: Bluetooth transceiver and WiFi transceiver, and one or more proximity sensors, each proximity sensor communicatively connected to the first controller and configured to measure the distance between the first side and an object located below the proximity sensor when the first side is facing downwards.

34. The system according to any one of claims 28 to 33, wherein the first controller and the second controller are jointly configured to: h) cause the wafer handling robot to position the automatic calibration wafer above the first wafer support, i) cause each first camera sensor to obtain a corresponding first image of the reference of the first wafer support when the automatic calibration wafer is positioned above the first wafer support, j) determine the position information of the center point of the first wafer support based on the first image, k) cause the wafer handling robot to retrieve the calibration wafer, l) cause the wafer handling robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer nominally lies on the center point of the first wafer support when viewed along the vertical axis, m) cause the wafer handling robot to position the automatic calibration wafer above the first wafer support and the calibration wafer, n) cause each first camera sensor to obtain a corresponding second image of the reference of the first wafer support when the automatic calibration wafer is located above the first wafer support and the calibration wafer, and determine the reference of the first wafer support and the reference of the calibration wafer, and o) Determine a wafer / wafer support horizontal offset between the center point of the calibration wafer and the center point of the first wafer support based on the gap size between the reference of the first wafer support and the reference of the calibration wafer in the second image, and p) Compare the wafer / wafer support horizontal offset with a threshold of the wafer / wafer support horizontal offset, and q) In response to determining that the wafer / wafer support horizontal offset is higher than the threshold of the wafer / wafer support horizontal offset, reposition the calibration wafer by the wafer handling robot relative to the first wafer support to reduce the wafer / wafer support horizontal offset.

35. The system according to any one of claims 28 to 33, wherein, The first controller and the second controller are jointly configured to: h) Cause the wafer handling robot to position the auto-calibration wafer above the first wafer station, i) Cause each first imaging sensor to obtain a corresponding first image of the reference of the first wafer support when the auto-calibration wafer is positioned above the first wafer support, j) Cause the wafer handling robot to retrieve the first edge ring, k) Cause the wafer handling robot to transfer the first edge ring to the first wafer support such that the center point of the first edge ring nominally lies on the center point of the first wafer support when viewed along the vertical axis, l) Cause the wafer handling robot to position the auto-calibration wafer above the first wafer support and the first edge ring, m) Cause each first imaging sensor to obtain a corresponding second image of the reference of the first wafer support and the reference of the first edge ring when the auto-calibration wafer is positioned above the first wafer support and the first edge ring, n) Determine an edge ring / wafer support horizontal offset between the center point of the first edge ring and the center point of the first wafer support based on the gap size between the reference of the first wafer support and the reference of the first edge ring in the second image.

36. The system according to claim 35, wherein the first controller and the second controller are jointly further configured to: o) Compare the edge ring / wafer support horizontal offset with a threshold edge ring / wafer support horizontal offset, and p) In response to determining that the edge ring / wafer support horizontal offset is higher than the threshold edge ring / wafer support horizontal offset, reposition the first edge ring by the wafer handling robot relative to the first wafer support to reduce the edge ring / wafer support horizontal offset.

37. The system according to claim 35, wherein the first controller and the second controller are jointly further configured to: o) Cause the wafer handling robot to retrieve the calibration wafer, p) Cause the wafer handling robot to transfer the calibration wafer to the first wafer support such that the center point of the calibration wafer nominally lies on the center point of the first edge ring when viewed along the vertical axis, q) Cause the wafer handling robot to position the auto-calibration wafer above the first wafer support, the calibration wafer and the first edge ring, r) Cause each first imaging sensor to obtain a corresponding second image of the reference of the calibration wafer and the reference of the first edge ring when the auto-calibration wafer is positioned above the first wafer support, the calibration wafer and the first edge ring, s) Determine an edge ring / waf er horizontal offset between the center point of the first edge ring and the center point of the calibration wafer based on the gap size between the calibration wafer and the reference of the first edge ring in the second image. t) Compare the edge ring / waf er horizontal offset to a threshold edge ring / waf er horizontal offset, and u) Responsive to determining that the edge ring / waf er horizontal offset is higher than the threshold edge ring / waf er horizontal offset, reposition the calibration wafer relative to the first edge ring by the wafer handling robot to reduce the edge ring / waf er horizontal offset.

38. The system according to claim 31, wherein the first controller and the second controller are jointly configured to: h) Cause the wafer handling robot to transfer the auto - calibration wafer to the first wafer station, and i) Cause one or more orientation sensors to obtain an inclination measurement of the substrate.

39. The system according to claim 32, wherein the first controller and the second controller are jointly configured to: h) Determine that one of the one or more wafer supports of the one or more wafer stations supports an edge ring, i) Cause the auto - calibration wafer to be placed on the edge ring, j) Cause each proximity sensor to measure the distance between the wafer support supporting the edge ring and the auto - calibration wafer, k) Determine one or more height measurements associated with the edge ring based on the one or more distances, l) Evaluate the one or more height measurements to determine whether the height associated with the edge ring exceeds a predetermined threshold, and m) Provide a notification when the height associated with the edge ring exceeds the predetermined threshold.

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