Electrostatic chuck motion control method for preventing wafer from being damaged

Abstract

Apparatus and methods for lifting a substrate from a substrate support include: i. Moving the substrate support and the substrate from a first position in a first direction toward a lift bar, the substrate support having through-holes, each of the through-holes configured to receive a corresponding lift bar; ii. Bringing the substrate into contact with the lifting bar when the substrate support and the substrate are moved; iii. After contacting the lifting rod, determining a force applied on the lifting rod; iv. Comparing the determined force on the lifting rod with a predetermined threshold force; and v. Determining that the force on the lift bar is greater than or equal to a threshold force and moving the substrate support away from the lift bar in a second direction opposite the first direction.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to methods, systems, and apparatus for substrate handling, and more particularly, to removing a substrate from a substrate support pedestal. Background Art

[0002] Physical vapor deposition (PVD) equipment often utilizes a Johnson-Rahbek (JR) or coulombic electrostatic chuck (ESC) to clamp a substrate to a substrate support base for PVD processing. Such chucks rely on electrostatic forces generated by opposite charges accumulated on the substrate and the ESC. After the PVD process, a de-chucking process may be performed to remove the accumulated charge to de-chuck the substrate so that the substrate can be lifted and transferred from the ESC for subsequent processing. However, residual electrostatic charge and clamping forces may remain after such de-chucking.

[0003] Lifting pins are often used to lift a substrate off the ESC. Such lifting pins can pass through holes in the ESC to contact the back side of the substrate and apply a force to the substrate to lift the substrate from the ESC. If there is a clamping force on the substrate, a force greater than the clamping force is required to lift the substrate off the ESC. However, if the force applied to each substrate by the lifting pins exceeds a certain force, the substrate may be damaged. Therefore, if the clamping force remaining on the substrate after unclamping is greater than a certain force, the force of the lifting pins on the substrate will exceed the certain force on the substrate and damage the substrate.

[0004] Thus, as disclosed herein, the inventors provide embodiments of improved substrate lifting methods and systems. Summary of the invention

[0005] Methods, systems, and non-transitory machine-readable storage media for lifting a substrate from a substrate support are provided herein.

[0006] In some embodiments, a method for lifting a substrate from a substrate support comprises: i. moving the substrate support and the substrate from a first position in a first direction toward lifting pins, the substrate support having a through hole, each of the through holes being configured to receive a corresponding lifting pin; ii. contacting the substrate with the lifting pins when moving the substrate support and the substrate; iii. determining a force applied to the lifting pins after contacting the lifting pins; iv. comparing the determined force on the lifting pins with a predetermined threshold force; and v. determining that the force on the lifting pins is greater than or equal to the threshold force, and moving the substrate support away from the lifting pins in a second direction opposite to the first direction.

[0007] In some embodiments, a substrate lifting system for controlling lifting of a substrate includes: a substrate support configured to support a substrate and to move vertically between a first position and a release position, the substrate support having a through hole; a lifting pin configured to pass through the through hole and contact a substrate supported by the substrate support; a motor coupled to the lifting pin and configured to vertically position the lifting pin; and a force feedback system configured to measure a force applied by the lifting pin against the substrate and return the substrate support to the first position if the force measured on the lifting pin is greater than or equal to a threshold force.

[0008] In some embodiments, a non-transitory machine-readable storage medium having processor-executable instructions stored thereon is provided, the instructions being used to cause a machine to perform a method for lifting a substrate from a substrate support, the method comprising: i. moving a substrate support and a substrate from a first position in a first direction toward a lifting pin, the substrate support having a through hole, each of the through holes being configured to receive a corresponding lifting pin; ii. bringing the substrate into contact with the lifting pin when moving the substrate support and the substrate; iii. determining a force applied to the lifting pin after contacting the lifting pin; iv. comparing the determined force on the lifting pin with a predetermined threshold force; and v. determining that the force on the lifting pin is greater than or equal to the threshold force, and moving the substrate support away from the lifting pin in a second direction opposite to the first direction.

[0009] Other and further embodiments of the disclosure are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The embodiments of the present disclosure briefly summarized above and discussed in more detail below can be understood by reference to the illustrative embodiments of the present disclosure depicted in the accompanying drawings. However, the accompanying drawings only illustrate common embodiments of the present disclosure and are therefore not to be considered limiting of the scope, as the present disclosure may admit to other equally effective embodiments.

[0011] Figure 1A is a schematic diagram of a system for lifting a substrate from a chuck according to an embodiment of the present disclosure.

[0012] Figure 1B A schematic diagram illustrating the forces acting on the lift pin under vacuum is shown.

[0013] Figures 2 to 6 Various steps of a method of lifting a substrate from a chuck according to the present disclosure are schematically illustrated.

[0014] Figure 2 is a schematic diagram illustrating a substrate supported on a substrate support being lowered from a first position onto lift pins.

[0015] Figure 3 is a schematic diagram illustrating the movement of a substrate into contact with a lift pin.

[0016] Figure 4 is a schematic diagram illustrating the subsequent lowering of the substrate from the first position onto the lifting pins.

[0017] Figure 5 is a schematic diagram illustrating the subsequent movement of the substrate into contact with the lifting pins.

[0018] Figure 6 is a schematic diagram of a substrate support in a released position, wherein the substrate is lifted from the substrate support by lift pins.

[0019] Figure 7 is a flow chart of a method of lifting a substrate according to an embodiment of the present disclosure.

[0020] Figure 8 is a high-level block diagram of a computing device suitable for use with embodiments for lifting a substrate according to the present disclosure.

[0021] For ease of understanding, the same reference numerals have been used to identify common elements in the figures where possible. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. DETAILED DESCRIPTION

[0022] Embodiments of methods, systems, and non-transitory machine-readable storage media for lifting a substrate from a substrate support are provided herein.

[0023] As described in more detail below, in some embodiments, closed loop control is used to prevent damage to the substrate. More specifically, in some embodiments, such closed loop control uses the lift pin drive response (motor torque or motor position) to control the force applied to the substrate by the lift pins. Using the lift pin drive response advantageously does not require retrofitting existing processing chambers with additional sensors or instrumentation (such as strain gauges) that may often fail under substrate processing conditions. Alternatively, as mentioned above, many processing chambers already include some form of open loop electric lift pin and substrate support control that can be upgraded to closed loop control while retaining process compatibility.

[0024] Figure 1A is a schematic diagram of a system 100 for lifting a substrate 102 from a substrate support 104 according to an embodiment of the present disclosure. In some embodiments, the system 100 may be located inside a chamber 106, which may be maintained under a vacuum.

[0025] In some embodiments, and as Figure 1A1 , the system 100 may include a substrate support 104 configured to support a substrate 102 and to move vertically between a first position 108 and a release position 110. In some embodiments, the substrate support 104 includes an ESC and may have a through hole 112. The substrate support 104 may be connected to a motor 126 configured to raise and lower the substrate support 104 in the chamber 106. In some embodiments, and as shown in FIG. 1 , the system 100 may include a lift pin 114 configured to pass through the through hole 112 and contact the substrate 102 supported by the substrate support 104. In some embodiments, and as shown in FIG. Figure 1A As shown, the lift pins 114 can be connected to a ring 116 to allow all lift pins 114 to be raised and lowered together. In some embodiments, the lift pins can be grounded (e.g., via the ring 116) and configured to discharge some residual charge on the substrate 102 via the lift pins 114 after contacting them.

[0026] In some embodiments, and as Figure 1A As shown, the system 100 may include a motor 118 coupled to the lifting rod 114 and configured to vertically position the lifting rod 114 in the chamber 106. In some embodiments, the motor 118 may be a servo motor or a stepper motor. In addition, in some embodiments, the system 100 may include a motor encoder 122, which is configured to measure the motor position corresponding to the vertical position of the lifting rod 114. In some embodiments, the motor encoder 122 and the motor 118 may be connected to a motor driver 124, such as an Ether-CAT (i.e., "ECAT") motor driver, which is configured to measure and output motor position changes and motor torque. Therefore, the motor driver 124 can be configured as a torque measurement device and a position measurement device.

[0027] In some embodiments, and as Figure 1A As shown, the system 100 may include at least one controller 120 coupled to the motor 118 (via a motor driver 124) and the substrate support 104 (via a motor 126). In some embodiments, the motor driver 124 may be integrated into the controller 120. In some embodiments, the controller 120 is configured to control the relative motion and position between the substrate support 104 and the lift pins 114. In some embodiments, the controller 120 may be configured to maintain a static vertical position of the lift pins 114 while moving the substrate support 104 toward the lift pins 114 and causing contact between the substrate 102 and the lift pins 114. In some embodiments, the controller 120 may be configured to maintain a static vertical position of the substrate support 104 while moving the lift pins 114 toward the substrate support 104 and the substrate 102.

[0028] In some embodiments, the controller 120 may be configured to determine a force exerted on the lift pins 114 by the substrate 102 (the force being equal to any electrostatic clamping force on the substrate 102), compare the determined force on the lift pins 114 to a predetermined threshold force, and if the determined force on the lift pins 114 is greater than or equal to the threshold force, raise the substrate support 104 to the first position 108. The force exerted on the lift pins 114 by the substrate 102 is equal to the residual electrostatic force (i.e., the clamping force) on the substrate 102.

[0029] In some embodiments, the controller 120 may be configured to continue moving the substrate support 104 in the first direction to the release position 110 if the determined force on the lift pins 114 from the substrate 102 is less than the threshold force, thereby causing the lift pins 114 to lift the substrate 102 off the substrate support 104 .

[0030] In some embodiments, the threshold force may be set to a substrate damage limit. Thus, any force applied to the substrate at or above the substrate damage limit will result in damage to the substrate, and any force applied to the substrate below the substrate damage limit will not result in damage to the substrate. In some embodiments, the threshold force may be based on characteristics of the substrate 102, such as mechanical properties (e.g., yield strength), and electrical properties (e.g., conductivity) of the substrate.

[0031] Figure 1B The force acting on the lifting pins 114 in various states of the substrate lifting process according to the present disclosure is schematically illustrated. Figure 1B In some embodiments, the weight of the substrate 102 is considered to be negligible. Figure 1B As shown, the pressure in the chamber 106 is maintained at a vacuum, which causes the lift pins 114 to experience a vacuum force F 真空 At the first time T1, the lifting pins 114 are controlled by the motor 118 to remain fixed relative to the chamber 106, and the lifting pins 114 are not in contact with the substrate 102. At the first time T1, the force F exerted by the motor 118 on the lifting pins 114 is 马达,1 Maintain the lifting rod 114 fixed and equal to the vacuum force F 真空 As discussed in more detail below, at a second time T2 after T1, the substrate 102 may be lowered by the substrate support 104 into contact with the lift pins 114, and if there is a residual charge on the substrate 102 (i.e., there is a clamping force on the substrate 102), the vacuum force F 真空 will be equal to the electrostatic force F 静电 The motor force F at time T2 马达,2 Therefore, when the vacuum force F in the chamber 真空 When the electrostatic force F is kept constant from T1 to T2, 静电will be equal to the motor force F at time T1 马达,1 and the motor force F at time T2 马达,2 The motor force can be obtained from the measurement of the motor torque or the lift rod displacement discussed below. In addition, if the motor force F at time T1 is 马达,1 and the motor force F at time T2 马达,2 The difference between them is zero, then the electrostatic force F 静电 will be zero.

[0032] In some embodiments, the controller 120 is configured to determine the force exerted on the lift pins 114 by the substrate 102 based on a measurement of the motor torque when the motor 118 maintains a static vertical position of the lift pins 114 in the chamber 106. For example, the motor torque may be equal to the product of the net force on the motor and a moment arm, which is a fixed value based on the physical configuration of the motor and lift pins 114.

[0033] In another embodiment, the force exerted on the lift pins 114 by the substrate 102 can be determined based on measuring the vertical movement of the lift pins 114 after contact with the substrate 102. For example, a change in motor position as measured by the motor encoder 122 can be used to determine a change in the vertical position of the lift pins 114. The controller 120 can correlate the determined change in the vertical position of the lift pins 114 with the force acting on the motor 118.

[0034] For example, in some embodiments, although the lift pins 114 are controlled to be maintained in a static vertical position, upon contact between the lift pins 114 and the substrate 102, the electrostatic force F 静电 Make the F on the lifting rod 114 真空 With F 马达 The balancing force of the lifting rod 114 is unbalanced. Due to the unbalanced force on the lifting rod 114, the electrostatic force F 静电 The lift pin 114 may be displaced vertically (eg, downward) based on the electrostatic force F 静电 The change in the vertical position of the lift pins 114 may be compared to a configurable threshold value, which may correspond to a threshold force. If the change in the vertical position of the lift pins 114 is equal to or greater than the threshold value, the lift pins 114 and the substrate 102 may be separated to avoid applying a force greater than the threshold force to the substrate 102. Otherwise, if the change in the vertical position of the lift pins 114 is less than the threshold value, the substrate support 104 and the substrate 102 may be moved (e.g., lowered) to the release position 110 to cause the lift pins 114 to lift the substrate support 104 away from the substrate 102.

[0035] Figures 2 to 7 Regarding a method 700 for lifting a substrate 102 using a system 100 such as described herein above according to an embodiment of the present disclosure. In some embodiments, and as Figure 7As shown, method 700 may begin at 701, where a substrate 102 is supported by a substrate support 104 at a first position 108, where the substrate 102 is vertically spaced from lift pins 114, such as Figure 2 As shown in FIG. 1 , since the lifting pins 114 are not in contact with the substrate 102, the force exerted on the lifting pins by the substrate 102 is zero, as shown by Figure 2 The indicator 202 in FIG. The force applied to the lifting rod 114 can be determined as discussed above.

[0036] At 702, the substrate support 104 and substrate 102 are moved vertically (eg, downwardly) from a first position 108 in a first direction toward lift pins 114 in the chamber 106, such as Figure 2 206. In some embodiments, the controller 120 controls the motor 118 to maintain the lift pins 114 at a vertical position relative to the chamber 106. At 703, at some point in the movement of the substrate support 104 and the substrate 102 between the first position and the release position, the substrate 102 contacts the lift pins 114. At 704, after the lift pins 114 are brought into contact with the substrate 102, a force applied to the lift pins 114 is determined. Figure 3 In the example shown, the determined force indicated on indicator 202 is equal to the threshold force represented by indicator 204 .

[0037] At 705, the determined force on the lift pins is compared to a predetermined threshold force. If the determined force on the lift pins 114 is equal to or greater than the threshold force ("yes" at 708), then at 707 the substrate support 104 and the substrate 102 are moved away from the lift pins 114 in a second direction opposite to the first direction, such as by Figure 3 The substrate support 104 may be returned to the first position, for example, as shown by arrow 306 in FIG. Figure 4 As shown, the substrate 102 may then undergo a de-chucking process at 708 to remove residual charge on the substrate 102 and reduce the clamping force on the substrate 102. After this de-chucking process, the method 700 may repeat 702-706, as shown. Figure 4 and Figure 5 As shown, until the determined force on the lifting rod 114 becomes less than the threshold force (“NO” at 706 ).

[0038] If the determined force on the lift pins 114 is less than the threshold force (“NO” at 706 ), then at 709 , the substrate support 104 and substrate 102 may continue to move in the first direction to the release position 110 , thereby causing the lift pins to lift the substrate 102 off the substrate support 104 , as shown in FIG. Figure 6 As shown. Figure 6As shown, the determined force indicated by indicator 202 is less than the threshold force 304. At 710, the method 700 may end, after which the substrate 102 may be transferred to another chamber coupled to the chamber 106 for additional substrate processing.

[0039] Thus, embodiments of the methods and systems described herein provide closed feedback control that checks whether the clamping force on the substrate is less than a threshold force that could damage the substrate if applied by the lift pins. Repeated unclamping can occur to reduce the clamping force to a level below the threshold force to allow safe lifting of the substrate from the ESC. Thus, embodiments of the methods and systems described herein can improve substrate throughput and process throughput.

[0040] Various embodiments of the method of lifting a substrate as described herein may be executed on one or more computer systems, which may interact with various other devices. One such computer system is Figure 8 A computer system 800 is shown, which may be implemented in various embodiments. Figure 1A and Figures 2 to 7 For example, according to one or more embodiments, the computer system 800 may be used to implement the controller 120 in various embodiments of the present disclosure.

[0041] In various embodiments, the computer system 800 may be configured to implement the method 700 described above. The computer system 800 may be used to implement any other system, device, element, functionality, or method of the embodiments described above. In the illustrated embodiment, the computer system 800 may be configured to implement the method 700 as processor executable program instructions 822 (e.g., program instructions executable by the processor 810) in various embodiments.

[0042] In the illustrated embodiment, the computer system 800 includes one or more processors 810a-810n coupled to a system memory 820 via an input / output (I / O) interface 830. The computer system 800 further includes a network interface 840 coupled to the I / O interface 830, and one or more input / output devices 850, such as a cursor control device 860, a keyboard 870, and a display 880. The network interface 840 can be connected to a communication network 890. In various embodiments, any of the components can be used by the computer system 800 to receive user input as described above. In various embodiments, a user interface can be generated and displayed on the display 880. In some cases, embodiments can be implemented using a single instance of the computer system 800, while in other embodiments, multiple such systems, or multiple nodes making up the computer system 800, can be configured to host different parts or instances of various embodiments. For example, in one embodiment, some elements can be implemented via one or more nodes of the computer system 800 that are different from those nodes that implement other elements. In another example, multiple nodes may implement computer system 800 in a distributed manner.

[0043] In different embodiments, the computer system 800 can be any of various types of devices, including but not limited to a personal computer system, a desktop computer, a laptop computer, a notebook, a tablet or notebook computer, a mainframe computer system, a handheld computer, a workstation, a network computer, a mobile device, a consumer device, an application server, a storage device, a peripheral device (such as a switch), a modem, a router, or any type of computing or electronic device in general.

[0044] In various embodiments, computer system 800 may be a uniprocessor system including one processor 810, or a multiprocessor system including several processors 810 (e.g., two, four, eight, or another suitable number). Processor 810 may be any suitable processor capable of executing instructions. For example, in various embodiments, processor 810 may be a general-purpose or embedded processor that implements any of a variety of instruction set architectures (ISAs). In a multiprocessor system, each of processors 810 may commonly, but not necessarily, implement the same ISA.

[0045] The system memory 820 may be configured to store program instructions 822 and / or data 832 that may be accessed by the processor 810. In various embodiments, the system memory 820 may be implemented using any suitable memory technology, such as static random-access memory (SRAM), synchronous dynamic RAM (SDRAM), non-volatile / flash type memory, or any other type of memory. In the illustrated embodiment, program instructions and data that implement any of the elements of the embodiments described above may be stored within the system memory 820. In other embodiments, the program instructions and / or data may be received, sent, or stored on different types of computer accessible media or on similar media separate from the system memory 820 or the computer system 800.

[0046] In one embodiment, the I / O interface 830 may be configured to coordinate I / O traffic between the processor 810, the system memory 820, and any peripheral devices in the device, including the network interface 840 or other peripheral interfaces, such as the input / output device 850. In some embodiments, the I / O interface 830 may perform any necessary protocol, timing, or other data transformations to convert data signals from one component (e.g., the system memory 820) into a format suitable for use by another component (e.g., the processor 810). In some embodiments, the I / O interface 830 may include support for devices attached via any type of peripheral bus, such as a variant of the Peripheral Component Interconnect (PCI) bus standard or the Universal Serial Bus (USB) standard, for example. In some embodiments, the functionality of the I / O interface 830 may be divided into two or more different components, such as a north bridge and a south bridge, for example. In addition, in some embodiments, some or all of the functionality of the I / O interface 830 (such as an interface to the system memory 820) may be integrated directly into the processor 810.

[0047] The network interface 840 may be configured to allow data to be exchanged between the computer system 800 and other devices attached to the network (such as one or more external systems) or between nodes of the computer system 800. In various embodiments, the communication network 890 may include one or more networks, including but not limited to a local area network (LAN) (e.g., an Ethernet network or a collaborative network), a wide area network (WAN) (e.g., the Internet), a wireless data network, some other electronic data network, or some combination of the above. In various embodiments, the network interface 840 may support communication via a general data network, whether wired or wireless, such as any suitable type of Ethernet network, for example; via a digital fiber optic communication network; via a storage area network, such as a Fibre Channel SAN, or via any other suitable type of network and / or protocol.

[0048] The input / output device 850 may include, in some embodiments, one or more display terminals, keyboards, keypads, touch pads, scanning devices, voice or optical recognition devices, or any other device suitable for entering or accessing data through one or more computer systems 800. Multiple input / output devices 850 may be present in the computer system 800 or may be distributed across various nodes of the computer system 800. In some embodiments, similar input / output devices may be separate from the computer system 800 and may interact with one or more nodes of the computer system 800 via a wired or wireless connection, such as via a network interface 840.

[0049] Those skilled in the art will appreciate that computer system 800 is merely illustrative and is not intended to limit the scope of the embodiments. Specifically, computer systems and devices may include any combination of hardware or software that can perform the indicated functions of the various embodiments. Computer system 800 may also be connected to other devices not shown, or alternatively may operate as a stand-alone system. In addition, the functionality provided by the components shown may be combined in fewer components or distributed in additional components in some embodiments. Similarly, in some embodiments, the functionality of some of the components shown may not be provided and / or other additional functionality may be available.

[0050] Those skilled in the art will also appreciate that, although various items are shown as being stored in memory or on storage when in use, these items or portions thereof may be transferred between memory and other storage devices for purposes of memory management and data integrity. Alternatively, in other embodiments, some or all of the software components may be executed in memory on another device and may communicate with the illustrated computer system via inter-computer communications. Some or all of the system components or data structures may also be stored (e.g., as instructions or structured data) on a computer-accessible medium or portable article to be read by an appropriate drive, various examples of which are described above. In some embodiments, instructions stored on a computer-accessible medium separate from the computer system 800 may be sent to the computer system 800 via a transmission medium or a signal (such as an electrical, electromagnetic, or digital signal) transmitted via a communication medium (such as a network and / or a wireless link). Various embodiments may further include receiving, sending, or storing instructions and / or data implemented according to the foregoing description on a computer-accessible medium or via a communication medium. Generally, computer accessible media may include storage media or memory media such as magnetic or optical media, for example, optical disks or DVD / CD-ROMs, volatile or non-volatile media such as RAM (e.g., SDRAM, DDR, RDRAM, SRAM, and the like), ROM, and the like.

[0051] Embodiments according to the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented as instructions stored using one or more machine-readable media, which may be read and executed by one or more processors. Machine-readable media may include any mechanism for storing or transmitting information in a machine-readable form (e.g., a computing device or a "virtual machine" running on one or more computing devices). For example, a machine-readable medium may include any suitable form of volatile or non-volatile memory.

[0052] For ease of discussion, the modules, data structures, and the like defined herein are defined as such, and are not intended to imply that any specific implementation details are required. For example, any described modules and / or data structures may be combined or divided into sub-modules, sub-processes, or other units of computer code or data, as may be required by a particular design or implementation.

[0053] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure.

Claims

1. A method of lifting a substrate from a substrate support, the method comprising: i. moving the substrate support and the substrate from a first position in a first direction toward lift pins, the substrate support having through holes, each of the through holes being configured to receive a corresponding lift pin; ii. When moving the substrate support and the substrate, the substrate is brought into contact with the lifting pin; iii. after contacting the lifting rod, determining the force applied on the lifting rod; iv. comparing the force determined on the lifting rod with a predetermined threshold force; as well as v. determining that the force on the lift pins is greater than or equal to the threshold force, and moving the substrate support away from the lift pins in a second direction opposite to the first direction.

2. The method of claim 1, further comprising: repeating i.-iv. until the determined force on the lifting rod is less than the threshold force.

3. The method of claim 2, further comprising: performing a de-chucking process on the substrate each time steps i.-iv. are repeated.

4. The method of any one of claims 1 to 3, further comprising: determining that the force on the lift pins is less than the threshold force, and continuing to move the substrate support in the first direction to a release position, thereby causing the lift pins to lift the substrate off the substrate support.

5. The method of any one of claims 1 to 3, wherein determining the force comprises: The motor torque of the motor that controls the static position of the lifting rod is measured.

6. The method of any one of claims 1 to 3, wherein determining the force comprises: A change in position of the lift pins is measured after the substrate is brought into contact with the lift pins.

7. The method of claim 6, wherein measuring the position change comprises: A motor position of a motor that controls the static position of the lifting rod is measured.

8. The method of any one of claims 1 to 3, wherein the threshold force is based on one or more characteristics of the substrate.

9. A substrate lifting system for controlling the lifting of a substrate, comprising: a substrate support configured to support the substrate and to move vertically between a first position and a release position, the substrate support having a through hole; a lift pin configured to pass through the through hole and contact a substrate supported by the substrate support; a motor coupled to the lift mast and configured to vertically position the lift mast; as well as A force feedback system is configured to determine a force exerted on the lift pins by the substrate and return the substrate support to the first position if the determined force is greater than or equal to a threshold force.

10. The system of claim 9, wherein if the determined force is less than the threshold force, the force feedback system is configured to move the substrate support in a first direction to the release position, thereby causing the lift pins to pass through the through-holes and causing the substrate to be lifted off the substrate support.

11. The system of claim 9, wherein the force feedback system comprises: a torque measuring device for measuring a motor torque of the motor after contact between the substrate and the lifting pin; as well as A controller is provided for controlling vertical movement of the substrate support based on the measured motor torque.

12. The system of claim 11, wherein the controller is configured to determine the force based on the measured motor torque and to raise the substrate support off the lift pins if the determined force is greater than or equal to the threshold force.

13. The system of claim 9, wherein the force feedback system comprises: an encoder configured to detect a motor position corresponding to a position of the lifting rod, and A controller is configured to control vertical movement of the substrate support based on the detected change in position of the motor after the substrate is brought into contact with the lift pins.

14. The system of claim 13, wherein the controller is configured to determine the force based on the detected change in the motor position and to raise the substrate support off the lift pins if the determined force is greater than or equal to the threshold force.

15. The system of claim 9, wherein the force feedback system comprises at least one controller coupled to the motor and the substrate support, the controller configured to maintain a vertical position of the lift pins while moving the substrate support toward the lift pins and causing contact between the substrate and the lift pins, determine a force exerted on the lift pins by the substrate, compare the determined force on the lift pins to a predetermined threshold force, and raise the substrate support to the first position if the determined force on the lift pins is greater than or equal to the threshold force.

16. A non-transitory machine-readable storage medium having stored thereon processor-executable instructions for causing a machine to perform a method of lifting a substrate from a substrate support, the method comprising: i. moving the substrate support and the substrate from a first position in a first direction toward lift pins, the substrate support having through holes, each of the through holes being configured to receive a corresponding lift pin; ii. When moving the substrate support and the substrate, the substrate is brought into contact with the lifting pin; iii. after contacting the lifting rod, determining the force applied on the lifting rod; iv. comparing the determined force on the lifting rod with a predetermined threshold force; as well as v. Determining that the force on the lift pins is greater than or equal to the threshold force, and moving the substrate support away from the lift pins in a second direction opposite the first direction.

17. The non-transitory machine-readable storage medium of claim 16, wherein the method further comprises: repeating i.-iv. until the determined force on the lift rod is less than the threshold force.

18. The non-transitory machine-readable storage medium of claim 17, wherein the method further comprises: performing a de-chucking process on the substrate each time i.-iv. is repeated.

19. The non-transitory machine-readable storage medium of any one of claims 16 to 18, wherein the method further comprises: determining that the force on the lift pins is less than the threshold force, and continuing to move the substrate support in the first direction to a release position, thereby causing the lift pins to lift the substrate off the substrate support.

20. The non-transitory machine-readable storage medium of any one of claims 16 to 18, wherein determining the force comprises: measuring a change in motor torque of a motor controlling a static position of the lift pins after contact between the lift pins and the substrate and determining the force based on the change in motor torque, or A change in position of the lift pins from a change in motor position is measured after the lift pins come into contact with the substrate and the force is determined based on the motor position change.

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