Method and apparatus for measuring wafer movement and placement using vibration data

Abstract

Embodiments disclosed herein include a sensor wafer. In an embodiment, the sensor wafer includes a substrate, wherein the substrate includes: a first surface; a second surface opposite the first surface; and an edge surface between the first surface and the second surface. In an embodiment, the sensor wafer further includes a plurality of sensor regions formed along the first surface, wherein the sensor regions include self-referencing capacitive sensors. In an embodiment, the sensor wafer further includes a vibration sensor embedded within the substrate.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 726,874, filed September 4, 2018, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] Embodiments relate to the field of semiconductor manufacturing, and in particular to a method and apparatus for measuring displacement of a sensor wafer caused by vibrations. BACKGROUND

[0004] In semiconductor manufacturing, process uniformity across a substrate is critical to providing a high yield. Therefore, it is desirable to place the substrate precisely on a support surface in order to provide uniform processing. In some processing tools, lift pins are used to raise and lower the substrate off of a support surface (e.g., electrostatic chuck (ESC)). However, the lift pins can be a source of displacement of the substrate in the X-Y direction. As such, raising and lowering the substrate with the lift pins can cause movement of the substrate, which results in the substrate not being centered with the support surface.

[0005] Vibrations of the lift pins can occur due to the lift pins not being properly aligned. Additionally, each of the plurality of lift pins can displace at different rates. In this case, the top surfaces of the lift pins (supporting the substrate) can not always be coplanar with each other, resulting in a tilted substrate, which can also cause undesirable wafer displacement. Currently, there is no sensor that properly correlates the lift pin vibrations with the substrate displacement. While a vibration sensor can be used to measure the vibrations from the lift pins, there is currently no feedback to identify when the vibrations are sufficient to cause wafer movement on the lift pins. SUMMARY

[0006] Embodiments disclosed herein include a sensor wafer. In an embodiment, the sensor wafer includes a substrate, wherein the substrate includes: a first surface; a second surface opposite the first surface; and an edge surface between the first surface and the second surface. In an embodiment, the sensor wafer further includes a plurality of sensor regions formed along the first surface, wherein the sensor regions include a self-referencing capacitive sensor. In an embodiment, the sensor wafer further includes a vibration sensor embedded within the substrate.

[0007] Embodiments disclosed herein include a method of measuring vibration-induced movement of a wafer in a processing tool. In an embodiment, the method includes placing a sensor wafer having a vibration sensor and a plurality of position sensors on a support surface in a processing tool. In an embodiment, the method further includes determining a first position of the sensor wafer relative to the support surface using the plurality of position sensors. In an embodiment, the method further includes raising and lowering the sensor wafer using a lift pin of the support surface while measuring vibrations of the sensor wafer using the vibration sensor. In an embodiment, the method further includes determining a second position of the sensor wafer relative to the support surface using the plurality of position sensors.

[0008] Embodiments disclosed herein include a computing system for detecting vibration-induced movement in a processing tool. In an embodiment, the computing system further includes a placement controller, wherein the placement controller is communicatively coupled to a sensor wafer supported by a support surface in the processing tool and a lift pin controller that controls displacement of a lift pin in the support surface that raises and lowers the sensor wafer. In an embodiment, the placement controller includes a sensor interface, wherein the sensor interface is communicatively coupled to the sensor wafer and receives data generated by position sensors and a vibration sensor of the sensor wafer. In an embodiment, the placement controller further includes a wafer center point module to determine a center point of the sensor wafer relative to a center point of the support surface from the data generated by the position sensors. In an embodiment, the placement controller further includes a vibration module to characterize an amount of vibration of the sensor wafer as the sensor wafer is displaced by the lift pin. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1A is a cross-sectional schematic view of a processing tool having a sensor wafer for measuring vibration and position of the sensor wafer, according to an embodiment.

[0010] Figure 1B is a cross-sectional schematic view of a processing tool having a sensor wafer supported by a lift pin that extends from a support surface, according to an embodiment.

[0011] Figure 1C is a cross-sectional schematic view of a processing tool having a sensor wafer supported by a lift pin that extends unevenly, causing a tilt of the sensor wafer, according to an embodiment.

[0012] Figure 1D is a cross-sectional schematic view of a processing tool having a sensor wafer and a profile of the sensor wafer displaced after raising and lowering a lift pin, according to an embodiment.

[0013] Figure 2A is a plan view of a bottom surface of a sensor wafer having a sensor region for measuring a position of the sensor wafer relative to a center of a support surface, according to an embodiment.

[0014] Figure 2B is a partial cross-sectional view of a sensor wafer having a bottom sensor region, according to an embodiment.

[0015] Figure 3 is a schematic diagram of a processing tool and a placement controller for determining whether a sensor wafer is displaced due to vibration, according to an embodiment.

[0016] Figure 4 is a flowchart of a process for determining whether vibration of a lift pin is sufficient to displace a sensor wafer, according to an embodiment.

[0017] Figure 5 shows a block diagram of an exemplary computer system that can be used in connection with a process including determining whether vibration of a lift pin is sufficient to displace a sensor wafer, according to an embodiment. DETAILED DESCRIPTION

[0018] Systems including a sensor wafer having a vibration sensor and a position sensor and methods of using such sensor wafers to determine whether vibration causes displacement of the sensor wafer are described according to various embodiments. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. Those skilled in the relevant arts will

[0019] As described above, lift pin vibration can cause unwanted movement of the wafer. Accordingly, embodiments disclosed herein provide a sensor wafer including a plurality of sensors for determining a relationship between lift pin vibration and position. Such embodiments are particularly beneficial because vibration of the lift pin can be detected and a direct impact of the lift pin vibration on the wafer position can be determined. Because lift pin vibration is generally always present, embodiments disclosed herein now provide a metric for determining when the vibration will exceed a predetermined threshold and cause displacement of the wafer. In one embodiment, testing of the lift pin vibration can be performed immediately after lift pin maintenance, eliminating the risk of processing misaligned wafers. Additionally, after process chemistry is performed in the chamber, no additional steps for verifying wafer position are needed to maintain chamber performance.

[0020] Reference is now made to Figure 1AThe diagram shows a schematic cross-sectional view of a processing tool 100 according to one embodiment. In one embodiment, the processing tool 100 may include a chamber 190. For example, the chamber 190 may be a vacuum chamber capable of providing a chamber pressure below atmospheric pressure. An exhaust and a vacuum pump (not shown) may be fluidly coupled to the chamber 190 to provide vacuum conditions within the chamber 190.

[0021] In one embodiment, the support surface 105 may be located within the chamber 190. The support surface 105 may be any suitable surface for supporting and securing a wafer (or other substrate). For example, the support surface 105 may be an electrostatic chuck (ESC) or the like. In one embodiment, a plurality of lifting rods 132 may be coupled to the support surface 105. The lifting rods 132 may be received in recesses 130 in the support surface 105. In one embodiment, the lifting rods 132 may be displaceable in the Z direction. The lifting rods 132 may be displaced within the support surface 105 together with one or more actuators (not shown).

[0022] exist Figure 1A The cross-section shown depicts two lifting rods 132. However, it should be understood that any number of lifting rods 132 may be used according to various embodiments. For example, the processing tool 100 may include three, four, or more than four lifting rods 132. The lifting rods 132 may be distributed on the support surface in any configuration.

[0023] While several specific components of the processing tool 100 are explicitly shown, it should be understood that any number of additional components commonly used in semiconductor manufacturing processes may also be included in the processing tool 100, as will be recognized by those skilled in the art. In one embodiment, the processing tool 100 may be a plasma processing tool (e.g., a plasma etching tool, a physical vapor deposition (PVD) tool, a plasma-enhanced chemical vapor deposition (PE-CVD) tool, a plasma-enhanced atomic layer deposition (PE-ALD) tool, etc.). Embodiments may also include processing tools 100 that are not plasma-based (e.g., CVD, ALD, furnace, etc.).

[0024] According to one embodiment, a sensor wafer 110 may be placed in a processing tool 100 to measure the vibration and displacement of the sensor wafer caused by the vibration of a lifting rod 132. In one embodiment, the sensor wafer 110 may include a first surface 112 and a second surface 114 opposite to the first surface. In one embodiment, the first surface 112 may be disposed on a surface 107 of a support surface 105. In one embodiment, the sensor wafer 110 may have a shape factor substantially similar to that of the substrate to be processed in the processing tool 100. For example, the sensor wafer 110 may have a diameter of approximately 300 mm. As will be described in more detail below, the sensor wafer 110 may include a plurality of sensors (Figure 1A In one embodiment, sensor wafer 110 can include one or more of a vibration sensor, an inclinometer sensor, and a position sensor.

[0025] Referring now to Figure 1B , a cross-sectional schematic of processing tool 100 is shown, with lift pins 132 in an extended position. Lift pins 132 can extend up and down in the Z direction, as indicated by the arrows. In one embodiment, extension and retraction of lift pins 132 can cause vibrations 133. Vibrations 133 can be a result of misalignment of lift pins 132. That is, lift pins 132 can be misaligned with slots 130. Vibrations 133 can also be generated in lift pins by any other mechanism. For example, vibrations 133 can be generated by displacement of actuators (not shown) used to displace lift pins 132.

[0026] In one embodiment, vibrations 133 of lift pins 132 can be transferred to sensor wafer 110, as a result of first surface 112 of sensor wafer 110 resting on a surface of lift pins 132 when lift pins 132 are extended. Vibrations transferred to sensor wafer 110 can cause displacement of the sensor wafer in the X-Y plane.

[0027] Referring now to Figure 1C , a cross-sectional schematic of processing tool 100 with non-coplanar lift pins 132 is shown, according to one embodiment. For example, first lift pins 132 can displace by a first distance Dl, while second lift pins 132 can displace by a second distance D2, which is less than first distance Dl. Lift pins 132 can have non-coplanar surfaces for a variety of reasons. For example, actuators used for each lift pin 132 can not be activated at the same time, or the actuators can not advance each lift pin 132 at the same rate. In this case, sensor wafer 110 can tilt. In some embodiments, tilt (also referred to as inclination) can be measured by an inclinometer sensor in sensor wafer 110. Tilt directions (e.g., pitch and roll) can determine in which direction (in the X-Y plane) sensor wafer 110 is displaced. As such, including tilt information in addition to vibration information can be used to more accurately track (or predict) movement of sensor wafer 110.

[0028] Referring now to Figure 1D , a cross-sectional view of processing tool 100 is shown, with sensor wafer 110 in a first position (i.e., sensor wafer 110 A ) and the same sensor wafer 110 in a second position (i.e., sensor wafer 110 B). As shown, the position of the sensor wafer 110 can be moved a distance S in the X-Y plane. For example, the sensor wafer 110 can have moved a distance S due to vibration or tilt of the lift pin 132 during the lifting or lowering of the wafer 110 in the Z direction.

[0029] In an embodiment, the sensor wafer 110 can have a plurality of sensors that correlate vibration and tilt to a positional displacement of the sensor wafer 110 relative to the support surface 105. In this way, it can be determined whether vibration or tilt of the lift pin 132 caused a displacement of the sensor wafer 110 in the X-Y plane. When movement of the sensor wafer 110 in the X-Y plane is detected, the lift pin 132 can be adjusted in order to reduce the vibration or tilt. Additional embodiments can include storing the vibration information and / or tilt information in a database that can be used as a threshold in the future. When a threshold is stored, a subsequent test can only require the vibration sensors and / or tilt sensors in order to determine whether movement occurred (i.e., if the vibration information and / or tilt information is greater than the threshold, it is expected that the wafer moved in the X-Y plane). In embodiments with tilt sensors, the direction of movement of the wafer can also be accurately predicted.

[0030] Referring now to Figure 2A , a plan view of a first surface 212 of a sensor wafer 210 is shown, according to an embodiment. As shown, the first surface 212 of the sensor wafer 210 can include a plurality of sensor regions 2651-265 n In an embodiment, the sensor regions 265 1-n may each include a plurality of sensors (e.g., capacitive sensors) configured to detect an edge of a support surface. By positioning the edge of the support surface at a plurality of positions (e.g., three or more positions) relative to the sensor wafer 210, a center point of the support surface relative to a center point of the sensor wafer 210 can be determined. In an embodiment, the sensor regions 265 can be linear groupings of capacitive sensors. In each sensor region 265, the capacitive sensors can extend from a center portion of the sensor wafer and to an edge of the sensor wafer 210.

[0031] In an embodiment, the sensor wafer 210 can include a computing module 240 that houses one or more of a power source 241, a processor / memory 242, a wireless communication module 243, a vibration sensor 244, and a tilt meter 245. The computing module 240 can be communicatively coupled to the bottom sensor regions 265 by conductive traces 247. In an embodiment, the vibration sensor 244 can be an accelerometer. In an embodiment, the accelerometer can be configured to detect vibration in only the X, Y, and Z directions. In an embodiment, the sensor wafer 210 can include a plurality of vibration sensors.

[0032] In one embodiment, the computing module 240 can include circuitry for providing current to the sensors of the sensor region 265 1-n . In one embodiment, the plurality of sensors can include a plurality of pairs of self-referencing capacitive sensors. In one embodiment, the current passed to the first conductive pad in each pair can have an output phase offset of 180 degrees from the output phase of the current passed to the second conductive pad in each pair.

[0033] In the illustrated embodiment, the computing module 240 is located approximately in the center of the sensor wafer 210. However, it should be understood that the computing module 240 can be located in any convenient location of the sensor wafer 210. Moreover, the components 241-245 can not be co-located in a single module. For example, one or more of the components 241-245 can be located outside of the computing module 240.

[0034] Referring now to Figure 2B , a partial cross-sectional illustration of a portion of the sensor wafer 210 and the support surface 205 is shown, according to one embodiment. As shown, the bottom sensor region 265 can be formed on a recessed portion of the first surface 212 that faces the surface 207 of the support surface 205 and extends to the edge 213 of the sensor wafer 210. In one embodiment, the bottom sensor region 265 can include an array of sensors (e.g., self-referencing capacitive sensors) that determine a spacing between the support surface 205 and the sensor region 265. Thus, at a location 201, the array of sensors in the bottom sensor region 265 will indicate the presence of the edge 203 of the support surface due to the lack of a detectable underlying surface of the sensor region 265. The location of the location 201 is known relative to the center of the sensor wafer 210. Thus, when three or more locations 201 are determined, the center point of the support surface 205 relative to the center point of the sensor wafer 210 can be calculated.

[0035] Referring now to Figure 3 , a schematic block diagram of a processing tool 390 having a placement controller 370 for implementing a process of measuring the vibration of the lift pin 332 and the resulting displacement of the sensor wafer 310 is shown, according to one embodiment. In one embodiment, the placement controller 370 can provide instructions to the lift pin controller 378 to raise and lower the sensor wafer 310 on the support surface 305 with the lift pin 332.

[0036] The sensor wafer 310 can be a sensor wafer similar to the sensor wafer described above. For example, the sensor wafer 310 can include a plurality of sensor regions to determine the edge locations 3031-303 n . Additionally, the sensor wafer 310 can include a vibration sensor (e.g., an accelerometer) and a tilt sensor.

[0037] In one embodiment, sensor information from sensor die 310 can be obtained through sensor interface 371 of placement controller 370. For example, sensor interface 371 can receive sensor information from sensor die 310 (e.g., wirelessly using a wireless communication module). Placement controller 370 can use the sensor information in center point module 372 (e.g., edge position 3031-303 n ) to determine the center point of sensor die 310 relative to the center point of support surface 305. As will be described below, center point module 372 can be used first to find a first position of sensor die 310, and second to find a second position of the sensor die after it has been raised or lowered one or more times by lift pins 332.

[0038] In one embodiment, placement controller 370 can also include vibration module 373. Vibration module 373 can process vibration information obtained by sensor interface 371 from vibration sensors on sensor die 310. In one embodiment, vibration module 373 can analyze the vibration information to determine the total amount of vibration, the maximum vibration, etc.

[0039] In one embodiment, placement controller 370 can also include tilt module 374. Tilt module 374 can process tilt information obtained by sensor interface 371 from tilt sensors on sensor die 310. In one embodiment, tilt module 374 can analyze the tilt information to determine the total amount of change in tilt during raising and lowering of lift pins 332, the maximum change in tilt of sensor die 310 during raising and lowering of lift pins 332, etc.

[0040] In one embodiment, placement controller 370 can generate die displacement thresholds 375 that are stored in database 376. In one embodiment, die displacement thresholds 375 can be sent to database 376 when a displacement of sensor die 310 in the X-Y plane is detected by center point module 372. In this case, information from vibration module 373 and / or tilt module 374 is stored and associated with the movement of sensor die 310. Thus, future measurements of vibration or tilt can be compared to the stored die displacement thresholds 375. If a die displacement threshold is exceeded, it can be assumed that the die has moved.

[0041] Reference is now made to Figure 4This diagram illustrates a process flow chart of process 480 for correlating vibration of a lifting rod with movement of a wafer according to one embodiment. In one embodiment, process 480 may begin with operation 481, which includes placing a sensor wafer having a vibration sensor and a plurality of position sensors on a support surface. In one embodiment, the sensor wafer may be any sensor wafer, such as those described herein. In one embodiment, the sensor wafer may further include a tilt sensor.

[0042] In one embodiment, process 480 may proceed to operation 482, which includes using a plurality of position sensors to determine a first position of a sensor wafer relative to a support surface. In one embodiment, the plurality of position sensors may determine the first position by detecting the edges of the support surface at multiple locations. Since the position of the center point of the sensor wafer relative to the sensor is known, the multiple edge locations can be used to calculate the center point of the sensor wafer relative to the center point of the support surface.

[0043] In one embodiment, process 480 may proceed to operation 483, which includes raising and lowering the sensor wafer using a lifting rod in a support surface, while simultaneously measuring the vibration of the sensor wafer using a vibration sensor. In one embodiment, the sensor wafer may be raised and lowered once or multiple times. For example, the sensor wafer may be raised and lowered five or more times. In embodiments including a tiltmeter sensor, the tilt of the sensor wafer may also be measured during the raising and lowering of the sensor wafer.

[0044] In one embodiment, process 480 may proceed to operation 484, which includes using multiple position sensors to determine a second position of the sensor wafer relative to a support surface. In one embodiment, the second position may be determined using substantially the same process as that used to determine the first position. For example, multiple position sensors may detect multiple support surface edge positions to determine the center point of the sensor wafer relative to the center point of the support surface. In one embodiment, the second position may be determined after a single iteration of raising and lowering the lifting rod. In another embodiment, the second position may be determined after multiple iterations of raising and lowering the lifting rod.

[0045] In one embodiment, a second position can be compared to a first position to determine if the sensor wafer has moved. If the sensor wafer has moved, it can be assumed that vibration and / or tilting of the lifting rod has caused the movement of the sensor wafer. In this case, a wafer displacement threshold, including information from vibration and / or tilt sensors, can be stored in a database for future reference. In embodiments where the lifting rod is shown displacing the sensor wafer in the XY plane, adjustments or other modifications to the lifting rod may be necessary. Because this measurement is performed before the substrate is processed in the tooling, the risk of handling misaligned wafers is eliminated.

[0046] Reference is now made to Figure 5 a block diagram of an exemplary computer system 560 of a processing tool, in accordance with an embodiment. In an embodiment, computer system 560 can be used as a placement controller. In an embodiment, computer system 560 is coupled to and controls processing in a processing tool. Computer system 560 can be connected, e.g., networked, to other machines in a network 561 (e.g., a Local Area Network (LAN), an intranet, an extranet, or the Internet). Computer system 560 can operate in the capacity of a server or a client machine in client-server network environments, or as a peer machine in peer-to-peer (or distributed) network environments. Computer system 560 can be a personal computer (PC), a tablet computer, a set-top box (STB), a personal digital assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated for computer system 560, the term "machine" shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein.

[0047] Computer system 560 can include a computer program product or software 522 having a non-transitory machine-readable medium (or more than one medium) storing instructions that can be used to program a computer system (or other electronic device) to perform a process according to embodiments. The machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, the machine-readable medium includes a machine (e.g., a computer) readable storage medium (e.g., read only memory ("ROM"), random access memory ("RAM"), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustical or other form of propagated signals (e.g., infrared signals, digital signals, etc.)), etc.

[0048] In an embodiment, computer system 560 includes a system processor 502, a main memory 504 (e.g., read-only memory (ROM), flash memory, a dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), Rambus DRAM (RDRAM), etc.), a static memory 506 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 518 (e.g., a data storage device), which communicate with each other via a bus 530.

[0049] The system processor 502 represents one or more general-purpose processing devices such as a microsystem processor, central processing unit, or the like. More particularly, the system processor can be a complex instruction set computing (CISC) microsystem processor, reduced instruction set computing (RISC) microsystem processor, very long instruction word (VLIW) microsystem processor, system processor implementing other instruction sets, or system processors implementing a combination of instruction sets. The system processor 502 can also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), network system processor, or the like. The system processor 502 is configured to execute the processing logic 526 to perform the operations described herein.

[0050] The computer system 560 can further include a system network interface device 508 for communicating with other devices or machines on a network. The computer system 560 can also include a video display unit 510 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 512 (e.g., a keyboard), a cursor control device 514 (e.g., a mouse), and a signal generation device 516 (e.g., a speaker).

[0051] The secondary memory 518 can include a machine-accessible storage medium 531 (or more specifically, a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software 522) embodying any one or more of the methodologies or functions described herein. The software 522 can also reside, completely or at least partially, within the main memory 504 and / or system processor 502 during execution thereof by the computer system 560, the main memory 504 and the system processor 502 also constituting machine-readable storage media. The software 522 can further be transmitted or received over a network 561 via the system network interface device 508.

[0052] While the machine-accessible storage medium 531 is shown in an example embodiment to be a single medium, the term "machine-readable storage medium" should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) that store the one or more sets of instructions. The term "machine-readable storage medium" shall also be taken to include any medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies

[0053] In the foregoing specification, specific exemplary embodiments have been described. It is evident, however, that various modifications can be made thereto without departing from the scope of the appended claims. The specification and drawings are, accordingly, to be regarded as illustrative rather than restrictive.

Claims

1. A sensor wafer comprising: a substrate, wherein the substrate comprises: a first surface; a second surface opposite the first surface; and an edge surface between the first surface and the second surface; a plurality of sensor regions formed along the first surface, wherein the sensor regions comprise a plurality of self-referencing capacitive sensors; and a vibration sensor embedded within the substrate, wherein each of the plurality of sensor regions extends radially from a central portion of the substrate and outwardly to the edge surface of the substrate, wherein the vibration sensor measures vibrations of the sensor wafer as the sensor wafer is raised and / or lowered by a plurality of rods in a processing chamber, and wherein vibration information from the vibration sensor is stored as a threshold when movement of the sensor wafer in an X-Y plane is detected, and the vibration information in subsequent tests is compared to the threshold to determine whether the sensor wafer is moving in the X-Y plane.

2. The sensor wafer of claim 1, wherein a plurality of surfaces of the sensor regions are recessed from the first surface.

3. The sensor wafer of claim 1, further comprising: an inclinometer sensor embedded in the substrate.

4. The sensor wafer of claim 1, wherein the sensor regions are used to detect an edge of a support surface supporting the sensor wafer.

5. The sensor wafer of claim 1, wherein the vibration sensor comprises an accelerometer.

6. The sensor wafer of claim 5, wherein the accelerometer senses acceleration along a plane parallel to the first surface.

7. The sensor wafer of claim 1, wherein a diameter of the sensor wafer is 300 mm.

8. A method of measuring vibration-induced movement in a processing tool, comprising: placing a sensor wafer as claimed in any of claims 1-7 on a support surface in the processing tool, the sensor wafer comprising a plurality of position sensors; determining a first position of the sensor wafer relative to the support surface using the plurality of position sensors; raising and lowering the sensor wafer using a plurality of lift rods of the support surface while measuring vibrations of the sensor wafer using the vibration sensor; and determining a second position of the sensor wafer relative to the support surface using the plurality of position sensors.

9. The method of claim 8, wherein the second position is determined after a plurality of times of raising and lowering the sensor wafer using the lift rods of the support surface.

10. The method of claim 9, wherein the plurality of times is at least five iterations of raising and lowering.

11. The method of claim 8, further comprising: comparing the first position to the second position.

12. The method of claim 11, further comprising: storing vibration information from the vibration sensor in a database. ​ 13. The method of claim 12, wherein the vibration information includes one or more of maximum acceleration, cumulative acceleration.

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