Method, system, and apparatus for performing a chucking operation using an adjusted chucking voltage when a process shift occurs

Abstract

Methods, systems, and apparatus are disclosed for performing a chucking operation using an adjusted chucking voltage when a process shift occurs. In one embodiment, the method includes performing a first processing step on a substrate in a processing chamber. The first processing step includes applying a chucking voltage to an electrostatic chuck (ESC) in the processing chamber while the substrate is supported on the ESC. The method includes determining that a process shift has occurred. Determining that a process shift has occurred includes one or more of determining that a center of the substrate has moved due to a post-processing shift relative to a pre-processing position of the center prior to the first processing step, and determining that a defect count on a backside surface of the substrate has exceeded a defect threshold. The method includes determining an adjusted chucking voltage based on the occurrence of the process shift.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate to semiconductor processing, and more particularly to electrostatic chucking of substrates. [Background technology]

[0002] Over the life of an electrostatic chuck, process drift can occur. For example, contaminants accumulating on the electrostatic chuck and / or roughening of the electrostatic chuck surface can change the chucking force applied to a substrate. Process drift can disrupt processing steps, cause substrate sticking and / or substrate breakage, cause substrate pop-off during processing, cause front-side and back-side defects on the substrate, and limit the operational life of the electrostatic chuck.

[0003] Therefore, there is a need for an improved electrostatic chuck and method of using the same. Summary of the Invention

[0004] Described herein are electrostatic chucks and methods for using the same. In one embodiment, a method for chucking a substrate includes performing a first processing step on the substrate in a processing chamber. The first processing step includes applying a chucking voltage to an electrostatic chuck (ESC) disposed in the processing chamber while the substrate is supported on the ESC. The method includes determining that a process shift has occurred. Determining that a process shift has occurred includes one or more of determining that a center of the substrate has moved due to a post-processing shift relative to a pre-processing position of the center before the first processing step, or determining that a defect count on the backside surface of the substrate has exceeded a defect threshold. The method includes determining an adjusted chucking voltage based on the occurrence of the process shift.

[0005] In one embodiment, a non-transitory computer-readable medium for performing a chucking operation includes instructions that, when executed, perform a plurality of steps. The plurality of steps includes performing a first processing step on a substrate within a processing chamber. The first processing step includes applying a chucking voltage to an electrostatic chuck (ESC) within the processing chamber while the substrate is supported on the ESC. The plurality of steps includes determining that a process shift has occurred. Determining that a process shift has occurred includes determining that the center of the substrate has moved due to a post-processing shift relative to the pre-processing position of the center before the first processing step, or determining that the number of defects on the back surface of the substrate has exceeded a defect threshold. The plurality of steps includes determining an adjusted chucking voltage based on the occurrence of the process shift.

[0006] In one embodiment, a system for processing a substrate includes a processing chamber that includes a processing space. The system includes an electrostatic chuck (ESC) disposed within the processing chamber. The system includes a controller that includes instructions that, when executed, cause the first processing chamber to perform a first processing step on the substrate within the processing chamber. The first processing step includes applying a chucking voltage to the ESC while the substrate is supported on the ESC. The instructions, when executed, cause a processor to determine that a process shift has occurred. Determining that a process shift has occurred includes determining that the center of the substrate has moved due to a post-processing shift relative to the pre-processing position of the center before the first processing step, or determining that the number of defects on the back surface of the substrate has exceeded a defect threshold. The instructions, when executed, cause the processor to determine an adjusted chucking voltage based on the occurrence of the process shift.

[0007] To better understand the above features of the present disclosure, a more specific description of the present disclosure briefly summarized above can be provided by referring to the embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings only show exemplary embodiments, and thus should not be regarded as limiting the scope, as the present disclosure allows other equally effective embodiments.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5

Figure 6

[0009] For ease of understanding, where possible, the same reference numbers are used to refer to the same elements common to multiple figures. It is assumed that the components and features of one embodiment can be beneficially incorporated into other embodiments without further description.

[0010] Aspects of the present disclosure relate to a method, system, and apparatus for performing a chucking operation using an adjusted chucking voltage when a process shift occurs.

[0011] FIG. 1 is a block diagram of a method 100 for chucking a substrate according to one embodiment. In step 102, a first processing step is performed on the substrate within a processing chamber. The first processing step includes applying a chucking voltage to an electrostatic chuck (ESC) within the processing chamber while the substrate is supported on the ESC. The chucking voltage is a predetermined chucking voltage selected to generate a target chucking force. The first processing step includes performing one or more of an etching step, a deposition step, an oxidation step, an annealing step, and / or an ion implantation step on the substrate while it is supported on the ESC.

[0012] After process 102, a process 104 for determining whether a process shift has occurred is executed. The occurrence of a process shift indicates that due to a change in the state of the ESC, a predetermined checking voltage no longer generates the target checking force. An ESC that allows a process shift can be referred to as a shifted ESC. Determining whether a process shift has occurred includes one or more of determining whether the center of the substrate has moved due to the post - processing displacement relative to the pre - processing position of the center before the first processing step, and / or determining whether the number of defects on the back - side surface of the substrate exceeds a defect threshold. The contamination of the back - side surface can be determined using the number of defects (such as particles) present on the back - side surface of the substrate. The post - processing displacement is the displacement of a predetermined threshold from the initial position (such as the center) before processing on the X - Y plane (for example, the horizontal plane). The predetermined threshold is in the range of 0.5 mm to 10 mm, for example, in the range of 1 mm to 5 mm. Determining whether the center of the substrate has moved due to the post - processing displacement includes lifting the substrate from the ESC and, after performing the first processing step, passing the substrate through the light emitted by one or more laser sensors to move the substrate. Passing the substrate through the light emitted by one or more laser sensors to move the substrate includes moving the substrate while supporting it on a robot blade. Determining whether the center of the substrate has moved due to the post - processing displacement also includes determining a plurality of positions located on the X - Y plane along the outer peripheral surface of the substrate and calculating the post - processing position of the center using the plurality of positions. Determining whether the center of the substrate has moved due to the post - processing displacement also includes determining the post - processing displacement between the post - processing position and the pre - processing position.

[0013] In one example, the defect threshold is in the range of 5,000 defects to 10,000 defects, for example, in the range of 8,000 defects to 10,000 defects. In one example, the defect threshold is greater than 10,000 defects. Determining whether a process shift has occurred in step 104 is performed in one or more processing chambers and / or a second chamber, such as a load lock chamber, a transfer chamber, a buffer chamber, an interface chamber, or a factory interface chamber.

[0014] In step 106, if a process shift has occurred, an adjusted chucking voltage is determined. In one embodiment that can be combined with other embodiments, determining the adjusted chucking voltage includes transferring a sensor substrate device onto an ESC in a processing chamber and measuring the chucking force applied to the sensor substrate device while the sensor substrate device is supported on the ESC. The sensor substrate device includes a plurality of embedded sensors that measure the electrostatic force applied to the sensor substrate device by the ESC. The adjusted chucking voltage is selected to generate a target chucking force by a shift ESC. In one embodiment that can be combined with other embodiments, determining the adjusted chucking voltage includes performing a pop-off process on a workpiece transferred onto a shift ESC in a first processing chamber. The workpiece includes a substrate or a second substrate.

[0015] The pop-off process includes applying an initial chucking voltage to the ESC and flowing backside gas to the backside surface of the workpiece. The initial chucking voltage is the voltage at which the backside gas leaks beyond the outer edge of the workpiece at a leakage rate below the leakage threshold. The initial chucking voltage can be the same as the chucking voltage applied in step 102, or can be lower or higher than the chucking voltage applied in step 102. The pop-off process also includes raising or lowering the initial chucking voltage until the backside gas leaks beyond the outer edge of the workpiece at a leakage rate exceeding the leakage threshold while flowing the backside gas to the backside surface of the workpiece. In one example, the backside gas is flowed at a backside pressure of about 16 Torr while the process space of the processing chamber is maintained at about 10 mTorr. The initial chucking voltage is raised or lowered in voltage increments such as 25 volts or 100 volts increments. The leakage threshold is in the range of 2.0 sccm (standard cubic centimeters per minute) to 5.0 sccm, for example 2.0 sccm.The adjusted chucking voltage is determined by adding a safety voltage margin to the leakage voltage or subtracting a safety voltage margin from the leakage voltage. When the leakage voltage is determined by lowering the initial chucking voltage to the leakage voltage, a safety voltage margin is added to the leakage voltage to provide an operating margin above the leakage voltage (for generating the target chucking voltage). When the leakage voltage is determined by raising the initial chucking voltage to the leakage voltage, a safety voltage margin is subtracted from the leakage voltage to provide an operating margin below the leakage voltage (for generating the target chucking voltage). The safety voltage margin is determined by multiplying the leakage voltage by a ratio coefficient, and the ratio coefficient is 0.2 or more. The safety voltage margin can be, for example, 200 volts or 300 volts.

[0016] In operation 108, a second processing step is performed within the processing chamber. The second processing step is performed on a substrate, a second substrate, or a third substrate. The second processing step includes applying an adjusted chucking voltage to the ESC while the substrate, the second substrate, or the third substrate is supported on the ESC. The adjusted chucking voltage is used to chuck the substrate, the second substrate, or the third substrate to the ESC during the second processing step. The second processing step includes one or more of an etching step, a deposition step, an oxidation step, an annealing step, and / or an ion implantation step.

[0017] FIG. 2 is a schematic partial view of a system 200 for processing a substrate that can be used to perform the method 100 shown in FIG. 1, according to one embodiment. The processing system 200 includes a processing chamber 201 and a second processing chamber 203. A controller 220 is connected to the processing chamber 201 and the second chamber 203 and controls the operation of the processing chamber 201 and the second chamber 203. The second chamber 203 includes a space 218 and a robot 227. The robot 227 has a robot blade 226 and is configured to extend the robot blade 226 into and retract the robot blade 226 from the processing space 206 of the processing chamber 201. The second chamber 203 can be a load lock chamber, a transfer chamber, a buffer chamber, an interface chamber, or a factory interface chamber. The second chamber 203 can be directly attached to the processing chamber 201 or the second chamber 203 can be detached (e.g., indirectly attached) from the processing chamber 201. The robot blade 226 is used to move substrates between the chambers 201, 203.

[0018] System 200 includes one or more sensors that monitor the state and / or characteristics of one or more aspects of the system 200, such as the space 118 of the second chamber 203, the processing space 206 of the processing chamber 201, and / or the surface of the substrate. System 200 includes one or more modules 290 (one shown), and the module 290 has one or more sensors 291a - 291d (four shown) disposed within the second chamber 203. At least one of the one or more sensors 291a - 291d is a particle sensor configured to measure the number of defects (such as contaminants) on the back surface of the substrate. In one example, the number of defects is measured in a tool or chamber that is not directly attached to the processing chamber 201. The sensors 291a - 291d can be measurement sensors, spectroscopic sensors on the substrate (such as X-ray fluorescence spectroscopy (XRF) sensors and / or X-ray photoelectron spectroscopy (XPS) sensors, etc.), particle counters, cameras, optical sensors, and / or position sensors.

[0019] System 200 includes one or more laser sensors 280 connected to the second chamber 203. Each of the laser sensors 280 is part of a local center finder (LCF) for the second chamber 203. The one or more laser sensors 280 can be disposed within or outside the space 218. The laser sensors 280 are used to detect at least three positions on the outer peripheral surface of the substrate (when carried on the robot blade 226), and then the center of the substrate is determined. By comparing the measured substrate center with the expected position based on the movement of the robot, it is possible to determine whether a position deviation has occurred on the ESC. The present disclosure contemplates that the one or more laser sensors 280 can be disposed within the processing chamber 201 or within the third chamber 205.

[0020] System 200 includes a third chamber 205 (measurement chamber) that is directly or indirectly connected to the second chamber 203. The third chamber 205 includes a particle sensor 293a, which is configured to measure the number of defects on the backside surface of the substrate after the first processing step has been performed on the substrate within the processing chamber 201. The particle sensor 293a is a measurement sensor, a spectroscopic sensor on the substrate (e.g., a fluorescent X-ray spectroscopy (XRF) sensor and / or an X-ray photoelectron spectroscopy (XPS) sensor, etc.), a particle counter, a camera, an optical sensor, and / or a position sensor. In one embodiment that can be combined with other embodiments, the particle sensor 293a configured to measure the number of defects is disposed within a third chamber 205 that is different from the processing chamber 201 and is not directly attached to the processing chamber 201. In such an embodiment, the substrate is removed from the processing chamber 201 before the number of defects is measured, and the number of defects is measured while the substrate is disposed within the third chamber 205 that is not directly attached to the processing chamber 201. In one embodiment that can be combined with other embodiments, the substrate is inverted such that the backside surface of the substrate faces upward, and the number of defects is measured using, for example, the particle sensor 293a within the third chamber 205. The third chamber 205 can be a load lock chamber, a transfer chamber, a buffer chamber, an interface chamber, or a factory interface chamber. The present disclosure contemplates that the particle sensor 293a can be disposed within the second chamber 203 or within the processing chamber 205. The present disclosure contemplates that one or more of the sensors 291a - 291d within the second chamber 203 can be configured to perform the operations described for the particle sensor 293a.

[0021] The third chamber 205 can include an inversion device that inverts the substrate such that the backside surface faces upward. The third chamber 205 can also include a robot, for example, a robot similar to the robot 227 disposed in the second chamber 203.

[0022] FIG. 3A is a schematic partial cross-sectional view of a processing chamber 300 according to one embodiment. The processing chamber 300 can be used as the processing chamber 201 of the system 200 shown in FIG. 2. The processing chamber 300 is an etching chamber configured to perform an etching process on a substrate 303. Suitable processing chambers that can be adapted for use in accordance with the aspects disclosed herein include, for example, ENABLER™, SYM3™, or AdvantEdge™ Mesa™ processing chambers available from Applied Materials, Inc., Santa Clara, Calif. The processing chamber 300 includes a chamber body 302 and a lid 304, which surround a processing space 306. The chamber body 302 is fabricated from aluminum, stainless steel, or other suitable material. The chamber body 302 includes sidewalls 308 and a bottom 320. A substrate access port 331 is defined in the sidewall 308 and is selectively sealed by a slit valve 333 to facilitate the transfer of the substrate 303 into and out of the processing chamber 300. An exhaust port 326 is defined in the chamber body 302 and connects the internal space 306 to a pump system 328. The pump system 328 generally includes one or more pumps and throttle valves utilized to evacuate and regulate the pressure in the processing space 306 of the processing chamber 300. In one embodiment, the pump system 328 maintains the pressure in the processing space 306 at an operating pressure typically between about 10 mTorr and about 500 Torr.

[0023] The lid 304 is supported on the side wall 308 of the chamber body 302 while being sealed. The lid 304 can be opened to allow for further expansion of the processing space 306 of the processing chamber 300. The lid 304 includes a window 324 that facilitates optical process monitoring. In one embodiment, the window 324 is composed of quartz or other suitable material that transmits signals utilized by an optical monitoring system 340 attached outside the processing chamber 300. The optical monitoring system 340 is arranged to observe at least one of the processing space 306 of the chamber body 302 and / or the substrate 303 disposed on the substrate support pedestal assembly 348 through the window 324. The substrate 303 includes a front surface 305 and a back surface 307. The optical monitoring system 340 is coupled to the lid 304 and is used to measure, for example, the structures formed on the front surface 305 from the perspective of the substrate 303, and / or to measure the number of defects (such as particles like contaminants) on the back surface 307. A defect map of the defects (such as particles) on the back surface 307 can be created using the optical monitoring system 340. The optical monitoring system 340 can function as an endpoint detector, optical emission spectroscopy (OES), secondary-ion mass spectrometry (SIMS), a signal detector, a photodetector, combinations thereof, and / or other suitable sensors or detectors associated with the processing chamber 300. The endpoint detector can be utilized to detect species within the processing chamber 300, for example, within the processing space 306, for example, in the vicinity of the front surface 305 of the substrate 303. During operation, the optical monitoring system 340 can send signals to the controller 220 to facilitate the operation and decision-making of the controller 220.

[0024] The gas panel 358 is coupled to the processing chamber 300 to supply a processing gas and / or a cleaning gas to the processing space 306. In the example shown in FIG. 3A, one or more inlet ports 332 (inlet ports 332', 332'') are provided in the lid 304 to enable the supply of gas from the gas panel 358 to the processing space 306 of the processing chamber 300. In one embodiment, the gas panel 358 is adapted to supply a fluorinated processing gas to the processing space 306 of the processing chamber 300 via the inlet ports 332', 332''. In one embodiment, the process gas supplied from the gas panel 358 includes at least a fluorinated gas, chlorine, a carbon-containing gas, an oxygen gas, a nitrogen-containing gas, and a chlorine-containing gas. Examples of the fluorinated gas and the carbon-containing gas include CHF3, CH2F2, and CF4. Other fluorinated gases may include one or more of C2F, C4F6, C3F8, and C5F8. Examples of the oxygen-containing gas include O2, CO2, CO, N2O, NO2, O3, H2O, etc. Examples of the nitrogen-containing gas include N2, NH3, N2O, NO2, etc. Examples of the chlorine-containing gas include HCl, Cl2, CCl4, CHCl3, CH2Cl2, CH3Cl, etc. Suitable examples of the carbon-containing gas include methane (CH4), ethane (C2H 6) , ethylene (C2H4), etc.

[0025] The showerhead assembly 330 is coupled to the inner surface 314 of the lid 304. The showerhead assembly 330 includes a plurality of apertures through which gas is distributed as desired across the surface of the substrate 303 being processed in the processing chamber 300, allowing the gas to flow through the showerhead assembly 330 from the inlet ports 332’, 332’’ into the processing space 306 of the processing chamber 300. Optionally, a remote plasma source 377 is coupled to the gas panel 358 to facilitate dissociating the mixed gas from the remote plasma source before entering the processing space 306 for processing. An RF power supply 343 is connected to the showerhead assembly 330 via a matching network 341. The RF power supply 343 is capable of generating up to approximately 3000 W at a tunable frequency in the range of about 50 kHz to about 200 MHz. The showerhead assembly 330 includes a region that permits transmission of an optical measurement signal. The optically transmissive region or passage 338 is suitable for an optical monitoring system 340 to observe the processing space 306 and / or the substrate 303 disposed on the substrate support pedestal assembly 348. The passage 338 can be a material, aperture, or plurality of apertures formed or disposed in the showerhead assembly 330 and substantially transmits the wavelength of the energy generated by the optical monitoring system 340 that is reflected and returned to the optical monitoring system 340.

[0026] The substrate support pedestal assembly 348 is disposed below the showerhead assembly 330 within the processing space 306 of the processing chamber 300. The substrate support pedestal assembly 348 holds and chucks the substrate 303 during processing. The substrate support pedestal assembly 348 typically includes a plurality of lift pins (not shown) disposed therethrough, which are configured to lift the substrate 303 from the substrate support pedestal assembly 348 to facilitate the exchange of the substrate 303 using a robot 227 that extends into the processing chamber 300 through the substrate access port 331. An inner liner 318 can closely surround the outer periphery of the substrate support pedestal assembly 348.

[0027] In one embodiment, the substrate support pedestal assembly 348 includes a mounting plate 362, a base plate 364, and an electrostatic chuck (ESC) 366. One or more materials, such as a bonding material, can be disposed between the ESC 366 and the base plate 364. The ESC 366 is formed of a ceramic material such as AlN or Al2O3. Alternatively, the ESC 366 may be an electrode laminated between polymer sheets. The mounting plate 362 is coupled to the bottom 320 of the chamber body 302 and includes passages for guiding utilities, such as fluid, power lines, and sensor leads, to the base plate 364 and the ESC 366. The ESC 366 includes at least one electrode 380 for chucking the substrate 303 to the ESC 366 to hold the substrate 303 below the showerhead assembly 330. A chucking power supply 382 is connected to the ESC 366 and is operable to apply a chucking voltage to the electrode 380 to generate an electrostatic force (chucking force) that chucks the substrate 303 to the chuck interface 311 of the ESC 366. The chucking power supply 382 is configured to apply a chucking voltage (e.g., a target chucking voltage, an initial chucking voltage, and an adjusted chucking voltage) within a range of up to 5,000 volts, such as from 0 volts to 2,000 volts, to the ESC 366.

[0028] At least one of the base 364 and the ESC 366 may include at least one optional embedded heater 376, at least one optional embedded isolator 374, and a plurality of conduits 368, 370 to control the lateral temperature profile of the substrate support pedestal assembly 348. The conduits 368, 370 are fluidly coupled to a fluid source 372 that circulates a temperature-conditioning fluid therethrough. The heater 376 is regulated by a power supply 378. The conduits 368, 370 and the heater 376 are utilized to control the temperature of the base plate 364, thereby controlling the heating and / or cooling of the ESC 366, and ultimately the temperature profile of the substrate 303 disposed thereon. The temperatures of the ESC 366 and the base plate 364 may be monitored using a plurality of temperature sensors 390, 392. In one embodiment, the substrate support pedestal assembly 348 is configured as a cathode, and the electrode 380 or the second electrode is connected to multiple RF bias power supplies 384, 386. The RF bias power supplies 384, 386 are connected between the electrode 380 disposed within the substrate support pedestal assembly 348 and another electrode, such as the showerhead assembly 330 or the ceiling 304 (lid 304) of the chamber body 302. The RF bias power supplies excite and sustain a plasma discharge formed from gases within the processing region of the chamber body 302. The RF bias power supplies 384, 386 are connected to the electrode 380 disposed within the substrate support pedestal assembly 348 through a matching network 388. Signals generated by the RF bias power supplies 384, 386 are supplied to the substrate support pedestal assembly 348 through a single supply line via the matching network 388 to ionize the gas mixture supplied into the processing chamber 300 and thus provide the ion energy necessary to perform a deposition, etching, or other process. The RF bias power supplies 384, 386 can generate RF signals having frequencies from about 50 kHz to about 200 MHz and powers from about 0 Watts to about 5000 Watts. An additional bias power supply 389 can be connected to the electrode 380 to control the characteristics of the plasma.

[0029] In one operating mode, the substrate 303 is supported on the ESC 366 of the substrate support pedestal assembly 348 within the processing chamber 300. Process gas and / or a mixed gas is introduced into the chamber body 302 from the gas panel 358 via the showerhead assembly 330. The vacuum pump system 328 maintains the pressure within the chamber body 302 while removing by-products.

[0030] FIG. 3B is an enlarged schematic view of the processing chamber 300 shown in FIG. 3A according to one embodiment. The chuck interface 311 includes an outer support surface 344. The ESC 366 includes a concave surface 345 disposed inward of the outer support surface 344 and a plurality of mesas 346 protruding upward with respect to the concave surface 345. The chuck interface 311 includes the upper surfaces 347 of the plurality of mesas 346. The ESC 366 includes a plurality of gas passages 349, such as grooves, between the plurality of mesas 346. The plurality of gas passages 349 are used to flow the backside gas G1 to the backside surface 307 of the substrate 303. The plurality of gas passages 349 are fluidly connected to a gas source that supplies the backside gas G1. The backside gas G1 can be helium or other suitable gas. During operation, the backside gas G1 is supplied into the gas passages at a controlled pressure to improve heat transfer between the ESC 366 and the substrate 303. The backside gas G1 can be supplied during the first processing step of method 100 (step 102), during the second processing step of method 100 (step 108), and during the pop-off step of method 100. The plurality of gas passages 349 can be fluidly connected to the gas source via at least one or more gas openings 351 formed in the ESC 366.

[0031] During the pop-off process described in method 100, the initial chucking voltage applied using the chucking power supply 382 is raised or lowered until the chucking voltage reaches the leakage voltage at which the backside gas G1 leaks beyond the outer edge 309 of the substrate 303 at a leakage rate exceeding the leakage threshold. Since the backside surface 307 is at least partially separated from the outer support surface 344, the backside gas G1 leaks between the backside surface 307 and the outer support surface 344 (as indicated by the phantom line in FIG. 3B). After the pop-off process, the substrate 303 can be removed from the processing chamber 300, and further, a second substrate (similar to the substrate 303) can be placed on the ESC 366, whereby a second processing step is performed on the second substrate within the processing chamber 300.

[0032] As described, defect counts can be measured outside the processing chamber 300 and in a different tool or chamber, such as a metrology chamber. Particle counts can be used to create a defect count map. Defects can deposit on the backside surface 307 from the backside gas G1 described in FIG. 2B and / or as a result of contact between the backside surface 307 and other components, such as the lift pins, the mesa 346, and / or the outer support surface 344. The particle sensor 293b is configured to measure the leak rate of the escaping backside gas G1 during the pop-off process. One or more laser sensors 280 located within the second chamber 203 of the system 200 are aligned below the substrate access port 331, such that the substrate 303 moves through light emitted by the one or more laser sensors 280 as the substrate 303 is transferred toward (e.g., into) and away from (e.g., exiting) the processing chamber 300. The one or more laser sensors 280 are configured to determine the center of the substrate 303 each time the substrate 303 moves through light emitted by the one or more laser sensors 280. When the substrate is transferred towards (e.g., into) the processing chamber 300, a pre-processing position of the center of the substrate 303 is determined using the one or more laser sensors 280. When the substrate is transferred away from (e.g., out of) the processing chamber 300, a post-processing position of the center of the substrate 303 is determined using the one or more laser sensors 280. The present disclosure contemplates that the sensors and / or operation of particle sensor 293 a, particle sensor 293 b, and / or one or more laser sensors 280 may be incorporated into the optical monitoring system 340.

[0033] The present disclosure contemplates that one or more laser sensors 280 may be located within the processing chamber 300, for example, located below the substrate access port 331 and attached to the sidewall 308.

[0034] The controller 220 is connected to the processing chamber 300 to control the operation of the processing chamber 300. The controller 220 includes a central processing unit (CPU) 231, a memory 232, and a support circuit 233 for the CPU 231. The CPU 231 can be any form of general-purpose computer processor that can be used in an industrial setting. The controller 220 controls the processing chamber 300 directly or via another computer or controller (not shown) connected to the processing chamber 300. The controller 220 can be any form of general-purpose computer processor that is used in an industrial setting to control various chambers and devices, as well as the sub-processors provided therein. The memory 232, or non-transitory computer-readable medium, is one or more readily available memories such as random access memory (RAM), read-only memory (ROM), floppy disk, hard disk, flash drive, or any other form of digital storage, local or remote. The support circuit 233 is connected to the CPU 231 to support the CPU. The support circuit 233 includes a cache, power supply, clock circuit, input / output circuit, and subsystems, etc. Substrate processing parameters and operations are stored in the memory 232 as software routines that are executed or called to convert the controller 220 into an application-specific controller for controlling the operation of the processing chamber 300. The controller 220 is configured to execute any of the methods described herein. The instructions stored in the memory 232, when executed, perform one or more of steps 102-108 of method 100.

[0035] The plurality of instructions executed by the controller 220 include instructions that enable one or more sensors 291a - 291d, one or more sensors 293a, 293b, and / or one or more laser sensors 280 to obtain measurement values. The instructions in the memory 232 of the controller 220 may include one or more machine learning / artificial intelligence algorithms that can be executed in addition to the processes described herein. As an example, the machine learning / artificial intelligence algorithm executed by the controller 220 can improve and / or change the operating parameters based on one or more sensor measurement values obtained by the sensors 291a - 291d, 293a, 293b, and / or 280. The operating parameters can include, for example, the number of defects, the leakage rate, the process shift, and / or the adjusted chucking voltage (each described above). The machine learning / artificial intelligence algorithm can be used to improve the chucking operation across a plurality of electrostatic chucks (ESCs) over the operating life of the ESCs for a plurality of ESCs.

[0036] FIG. 3C is an enlarged schematic view of the processing chamber 300 shown in FIG. 3A, which includes a sensor substrate device 353 within the processing chamber 300 according to one embodiment. The substrate 303 is lifted from the ESC 366 and removed from the processing chamber 300 using the robot 227. The robot 227 is used to place the sensor substrate device 353 on the ESC 366. The sensor substrate device 353 includes one or more substrates, for example, a first substrate 355 and a second substrate 357 disposed on the first substrate 355. The surface of the first substrate 355 and the surface of the second substrate 357 define a cavity 359. A plurality of sensors 360 are disposed within the cavity 240 between the first substrate 355 and the second substrate 357. The second substrate 357 is attracted to the ESC 366 by a chucking voltage, whereby the second substrate 357 applies a compressive force to the plurality of sensors 360. By monitoring the plurality of sensors 360, the applied force applied to the sensor substrate device 353 by the ESC 366 during the application of the chucking voltage is measured. The first substrate 355 and the second substrate 357 may be formed of silicon. The plurality of sensors 360 are pressure sensors such as spring gauge sensors, piezoelectric sensors, and / or microelectromechanical system (MEMS) sensors. The sensor substrate device 353 includes a calculation module 361. The calculation module 361 may include components (e.g., a processor and / or a memory) for calculating, recording, and / or communicating the measured value of the applied force applied to the sensor substrate device 353 by the ESC 366 during the application of the chucking voltage. The measured value can be transmitted, for example, to the controller 220 using a transmitter or a wired connection. The measured value can be stored in the sensor substrate device 353 and later downloaded to the controller 220.

[0037] The sensor 360 is mechanically and electrically connected between the first substrate 355 and the second substrate 357. Each sensor 360 is electrically connected to a respective first conductive pad 363 on the first substrate 355 and / or a second conductive pad 365 on the second substrate 357. The conductive pads 363, 365 can be electrically connected to the calculation module 361 (e.g., by conductive traces (not shown)). The present disclosure contemplates that the first conductive pad 363 or the second conductive pad 365 can be omitted.

[0038] FIG. 4 is a schematic view of a defect number map 400 of the back surface 307 of the substrate 303 obtained after a first processing step according to an embodiment. A plurality of defects 401 exist on the back surface 307. The defect number map 400 includes the number of defects for the plurality of defects 401. The plurality of defects 401 can include contamination particles, scratches, and / or chips. The plurality of defects 401 can be deposited on the back surface 307 as a result of contact between the backside gas and / or between the back surface 307 and other components such as the lift pins and / or surfaces of the ESC.

[0039] FIG. 5 is a schematic top view of a substrate 303 supported on a robot blade 226 of the robot 227 shown in FIG. 3A, according to one embodiment. As the robot blade 226 and the substrate 303 supported on the robot blade 226 extend into the processing chamber 300 toward the substrate access port 331 and further toward the ESC 336, the robot blade 226 and the substrate 303 move in a first direction D1 in the X-Y plane. While the robot blade 226 and the substrate 303 are moving in the first direction D1, the substrate 303 moves through light emitted by one or more laser sensors 280 within the second chamber 203. As the substrate 303 moves through the light emitted in the first direction D1 by one or more laser sensors 280, the substrate 303 (e.g., the outer peripheral surface of the substrate 303) blocks the light and one or more laser sensors 280 are triggered. The one or more laser sensors 280 are triggered when the emitted light is no longer reflected and collected at the same level by the one or more laser sensors 280 before the substrate 303 blocks the light. The light blocked by the substrate 303 is used to measure a plurality of first positions 501-504 along the outer peripheral surface 510 of the substrate 303. Each of the plurality of first positions 501-504 is located in the X-Y plane and has respective X coordinates (X1) and Y coordinates (Y1). The first positions 501-504 are used to calculate a pre-processing position 505 of the center of the substrate 303 before a first processing step is performed.

[0040] While the robot blade 226 and the substrate 303 supported on the robot blade 226 are taken out of the processing chamber 300 away from the ESC 366 and further away from the substrate access port 331, the robot blade 226 and the substrate 303 move in a second direction D2 in the X-Y plane. While the robot blade 226 and the substrate 303 are moving in the second direction D2, the substrate 303 moves through the light emitted by one or more laser sensors 280. While the substrate 303 is moving through the light emitted in the second direction D2 by one or more laser sensors 280, the substrate 303 (e.g., the outer peripheral surface of the substrate 303) blocks the light and one or more laser sensors 280 are triggered. When the emitted light is no longer reflected and collected by one or more laser sensors 280 at the same level as before the substrate 303 blocks the light, one or more laser sensors 280 are triggered. The light blocked by the substrate 303 is used to measure a plurality of second positions 511-514 along the outer peripheral surface 510 of the substrate 303. Each of the plurality of second positions 511-514 is located in the X-Y plane and has its respective X coordinate (X2) and Y coordinate (Y2). The second positions 511-514 are used to calculate the post-processing position 515 of the center of the substrate 303 after the first processing step is performed on the substrate 303. The post-processing deviation 520 between the post-processing position 515 and the pre-processing position 505 is determined by determining the distance between the post-processing position 515 and the pre-processing position 505. The post-processing deviation 520 can include an X-axis deviation and a Y-axis deviation. The post-processing deviation 520 is a difference such as the distance between the pre-processing position 505 and the post-processing position 515.

[0041] For each of the pre - processing position 505 and the post - processing position 515, the respective first positions 501 - 504 and the second positions 511 - 514 are used together with known parameters of the substrate 303 (such as radius R1) in the Pythagorean calculation for calculating the pre - processing position 505 and the post - processing position 515. In one example, half of the first Y - distance DY1 between the first position 501 and the first position 503 is used together with the radius R1 in the Pythagorean calculation, and the first X - distance DX1 between the first Y - distance DY1 and the pre - processing position 505 of the center of the substrate 303 is calculated. Half of the second Y - distance DY2 between the first position 502 and the first position 504 is used together with the radius R1 in the Pythagorean calculation, and the second X - distance DX2 between the second Y - distance DY2 and the pre - processing position 505 of the center of the substrate 303 is calculated.

[0042] It is possible to determine each of the pre - processing position 505 and the post - processing position 515 with respect to a reference point 530 and determine the post - processing deviation 520. The reference point 530 can be a reference point arranged along the robot blade 226, for example, along the central axis 531 of the robot blade 226.

[0043] FIG. 6 is a schematic side view of a substrate 303 supported on a robot blade 226 of a robot 227 shown in FIG. 3A according to an embodiment. The central cover 30 defining the upper limit of the space 218 of the second chamber 203 (for example, a transfer chamber) has a generally circular opening 32 sealed by a window 34 which may be a thick plexiglass plate, enabling the interior of the second chamber 203 to be viewed from above.

[0044] One or more laser sensors 280 detect when the outer peripheral surface of the substrate 303 blocks the light beam 36 passing through the second chamber 203. This can be done in various ways. For example, a light source can be placed on the central cover 30 and the light beam can be directed through the window 34 onto the surface of the photodetector. The output of the photodetector has a first value when the light beam is incident on the surface of the photodetector and a second value when the light beam is not incident on the photodetector (e.g., when the light beam is blocked by the substrate 303). When the outer peripheral surface of the substrate 303 passes through the light beam path 36 and blocks the path from the light source (one or more laser sensors 280) to the detector, the output of the detector changes from the first value to the second value. By noting the position of the robot 227 when the detector output changes value, it is possible to determine the center information of the substrate 303. A controller 68 is provided within the system 200. The controller 68 derives the center information of the substrate 303 from the information provided by the robot 227 and the one or more laser sensors 280. As schematically shown in FIG. 2, the controller 68 can be connected to the controller 220. The controller 68 can communicate with the controller 220 or can be incorporated into the controller 220.

[0045] One or more laser sensors 280 emit a light path 36 and output a signal of a first value when the light path 36 is not blocked, and output a signal of a second value when the light path 36 is blocked (e.g., when blocked by the substrate 303). Each of the one or more laser sensors 280 includes a reflective sensor 38 having a light source and a detector within a single housing. The reflective sensor 38 may include a Comet 100 Visible Red Reflex Sensor, DC model 14102A6517, manufactured by Eaton Corporation of Everett, Washington. FIG. 6 shows one or more laser sensors 280 disposed outside the second chamber 203, together with the light source and the detector. The light 36 from the reflective sensor 38 passes through the window 34 of the central cover 30 into the second chamber 203 and is further directed toward the floor of the second chamber 203. The light 36 is reflected from the reflector 40 and returns toward the reflective sensor 38, and the returned light ray is detected by the detector within the reflective sensor 38. In one embodiment, the reflector 40 includes a corner cube prism. A corner cube has the property that any light ray incident within a given solid angle from the normal of the surface of the corner cube is reflected back toward the source of the light ray (e.g., the reflective sensor). A corner cube prism generally has the shape of a cube cut along a diagonal plane of the cube, leaving only one corner of the cube intact. When used as a reflector, the corner cube is arranged such that light is incident on the diagonal plane and is substantially directed toward the remaining corners of the cube. Light rays incident on the surface of the corner cube reflector are reflected back toward the source of the light ray even when the surface of the corner cube is not perpendicular to the incident light ray. Correspondingly, the corner cube need not be precisely aligned when used as the reflector 40 of the present disclosure. The present disclosure contemplates that other reflectors, such as mirrors, may be used for the reflector 40.The corner cube can be, for example, a corner cube prism with part number 42.0015, manufactured by the Rolyn Optics Company of Covina, California.

[0046] The reflection sensor 38 is attached to the window 34 by a holder 44 that allows for slight adjustment of the position of the reflection sensor 38. The reflector 40 is attached to the bottom of the cover of the second chamber 203 by a stable holder 46. The holders 44 and 46 are arranged such that the optical path between the reflection sensor 38 and the reflector 40 blocks the outer peripheral surface of the substrate 303 being transferred by the robot blade 226 at a position that is away from (e.g., outside of) the end of the robot blade 226 (not shown in FIG. 6).

[0047] The one or more laser sensors 280 have several advantages for use within the system 200 of the present application. The reflection sensor 38 preferably emits and detects modulated visible laser light (such as red light), thereby enabling the reflection sensor 38 to distinguish the light beam 36 from the visible background radiation typically present within the wafer processing environment. By synchronizing the photodetector within the reflection sensor 38 with the modulation signal used to modulate the input red light signal, the likelihood of false signal detection is reduced. The likelihood of false signals is also reduced by the detection geometry and orientation of the one or more laser sensors 280. All of the reflection sensor 38, the optical path 36, and the normal to the surface of the reflector 40 are arranged at an oblique angle with respect to the surface of the window 34 of the central cover 30, reducing the likelihood of detecting light reflected by the window 34 or the wafer 10. This geometry also reduces the likelihood that background or ambient light sources will be erroneously detected as substrate position signals by the reflection sensor 38.

[0048] The reflective sensor 38 has the further advantage that when the intensity of the light incident on the detector rises above or falls below a predetermined threshold level, the output of the detector switches between two signal levels corresponding to the typical logic values 1 and 0 of a computer system. Correspondingly, the output of the reflective sensor 38 is easily adaptable to the controller 220 that controls the substrate transfer and the system 200 of the present disclosure. When a photodetector that outputs a signal that is not directly compatible with a computer is used, the output of the detector is converted into a signal that is compatible with the computer by a method (such as a signal conversion method).

[0049] Advantages of the present disclosure include accurate determination of voltage regulation, improvement of the chucking voltage, and maintenance of the target chucking force, improvement of the processing step and processing accuracy, reduction or elimination of the possibility of substrate sticking and / or substrate breakage, reduction or elimination of the possibility of substrate pop-off, reduction of the occurrence of front-side defects and back-side defects, and extension of the operating life of the electrostatic chuck. The advantages of the present disclosure also include shortening of the operation time, reduction of the replacement cost and operation cost, shortening of the machine downtime, reduction of the resource consumption, and improvement of the throughput. The technology described in this specification can determine whether the chucking force applied to the substrate has changed when the same chucking voltage is applied, and further promotes the improvement of the force control between substrates over the life of the ESC. Such changes in the chucking force may be due to the deposition of contaminants on the ESC surface (e.g., the concave surface 345), roughening of the ESC surface (such as by exposure to plasma), and / or the gradual removal of the ESC material (such as erosion or wear of a part of a plurality of mesas 346 caused by repeated processing). The advantages of the present disclosure also include using an existing chamber apparatus to accurately determine whether an adjusted chucking voltage is required based on the occurrence of a process shift.

[0050] The technology described herein realizes the aforementioned advantages with respect to conventional processes that include measuring a voltage on a substrate and processes that include measuring a pressure or a force on a substrate. The technology described herein promotes beneficial results for other processes with respect to efficiency and accurate maintenance of a target checking voltage. As an example, the technology described herein promotes beneficial results for other processes because it is possible to accurately account for the checking force applied to the substrate without relying on measuring current or voltage within a chamber. As another example, the technology described herein can accurately determine in real time when voltage adjustment is needed.

[0051] The foregoing description is directed to embodiments of the present disclosure, but other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof. The present disclosure also contemplates that one or more aspects of the embodiments described herein may be replaced with one or more other aspects described. The scope of the present disclosure is defined by the following claims.

Claims

1. A method for chucking a substrate, comprising: executing a first processing step on the substrate in a processing chamber, the first processing step including: applying a chucking voltage to an electrostatic chuck (ESC) in the processing chamber while the substrate is supported on the ESC; executing the first processing step; determining that a process shift has occurred, the determination including determining that the center of the substrate has moved from a pre-processing position of the center prior to the first processing step to a post-processing position due to a post-processing shift, and determining whether the center of the substrate has moved due to the post-processing shift by: lifting the substrate from the ESC; after executing the first processing step, while moving the substrate laterally by passing light emitted by a plurality of sensors, determining a plurality of positions located on an XY plane along an outer peripheral surface of the substrate; calculating the post-processing position of the center using the plurality of positions; determining whether a distance between the post-processing position and the pre-processing position satisfies or exceeds a predetermined threshold; determining that a process shift has occurred; determining an adjusted chucking voltage based on the occurrence of the process shift.

2. The method according to claim 1, wherein the predetermined threshold is in a range of 0.5 mm to 10 mm.

3. The method according to claim 1, wherein moving the substrate by passing the light emitted by the plurality of sensors includes moving a robot blade while supporting the substrate on the robot blade.

4. Determining the adjusted chucking voltage includes performing a pop-off process on a workpiece, the workpiece including the substrate or a second substrate, and the pop-off process including: applying an initial chucking voltage to the ESC supporting the workpiece; flowing backside gas to a backside surface of the workpiece; raising or lowering the initial chucking voltage until the backside gas leaks beyond an outer edge of the workpiece at a leakage rate exceeding a leakage threshold. The method according to claim 1.

5. The method according to claim 4, wherein the leakage threshold is within a range of 2.0 sccm to 5.0 sccm.

6. The method according to claim 4, wherein the adjusted chucking voltage is determined by adding a safety voltage margin to the leakage voltage or subtracting the safety voltage margin from the leakage voltage.

7. Further comprising performing a second processing step on the substrate, the second substrate, or the third substrate in the processing chamber, the second processing step comprising: Applying the adjusted chucking voltage to the ESC while the substrate, the second substrate, or the third substrate is supported on the ESC, according to the method of claim 6.

8. A non-transitory computer-readable medium for performing a chucking operation, comprising a plurality of instructions that, when executed, perform a plurality of steps, the plurality of steps comprising: Performing a first processing step on a substrate in a processing chamber, the first processing step comprising: Applying a chucking voltage to an electrostatic chuck (ESC) in the processing chamber while the substrate is supported on the ESC; Performing a first processing step including; Determining that a process shift has occurred, the determining including determining that the center of the substrate has moved from a pre-processing position of the center prior to the first processing step to a post-processing position due to a post-processing shift, and determining whether the center of the substrate has moved due to the post-processing shift includes: Lifting the substrate from the ESC; After performing the first processing step, while moving the substrate laterally by passing light emitted by a plurality of sensors, determining a plurality of positions located on the X-Y plane along the outer peripheral surface of the substrate; Calculating the post-processing position of the center using the plurality of positions; Determining that the distance between the post-processing position and the pre-processing position meets or exceeds a predetermined threshold; Determining that a process shift has occurred, including; Determining an adjusted chucking voltage based on the occurrence of the process shift, a non-transitory computer-readable medium.

9. The non-transitory computer-readable medium according to claim 8, wherein the predetermined threshold is within a range of 0.5 mm to 10 mm.

10. The non-transitory computer-readable medium according to claim 9, wherein moving the substrate by passing the light emitted by the plurality of sensors includes moving the robot blade while supporting the substrate on the robot blade.

11. Determining the adjusted chucking voltage includes performing a pop-off process on a workpiece, the workpiece including the substrate or a second substrate, and the pop-off process includes applying an initial chucking voltage to the ESC that supports the workpiece; flowing a backside gas to the backside surface of the workpiece; raising or lowering the initial chucking voltage until the backside gas leaks beyond the outer edge of the workpiece at a leakage rate exceeding a leakage threshold; The non-transitory computer-readable medium according to claim 8.

12. The non-transitory computer-readable medium according to claim 11, wherein the leakage threshold is in the range of 2.0 sccm to 5.0 sccm.

13. The non-transitory computer-readable medium according to claim 11, wherein the adjusted chucking voltage is determined by adding a safety voltage margin to or subtracting a safety voltage margin from the leakage voltage.

14. The plurality of instructions further includes performing a second processing step on the substrate, the second substrate, or a third substrate in the processing chamber, and the second processing step includes applying the adjusted chucking voltage to the ESC while the substrate, the second substrate, or the third substrate is supported on the ESC. The non-transitory computer-readable medium according to claim 13.

Images