Substrate Processing Equipment

Abstract

To appropriately pass over a substrate to a holding surface even if the holding surface falls in height in a substrate processing device.SOLUTION: A substrate processing device 1 at least includes: a table 30 having a holding surface 302 which holds a substrate 90; a height measurement unit 381 which measures the height of the holding surface 302; a transfer arm 2 which transfers the substrate 90 to the table 30; a drive unit 28 which falls the transfer arm 2 to a handover height of loading the substrate 90 on the holding surface 302; and a control unit 19. The control unit 19 controls to fall the handover height of the transfer arm 2, when the holding surface 302 falls in height, by a distance that the height of the holding surface 302 measured by the height measurement unit 381 has fallen from the height of the holding surface 302 having been recognized in advance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate processing apparatus for processing substrates such as semiconductor wafers. [Background technology]

[0002] The height of the holding surface decreases when the holding surface of the holding table disposed in the processing device is worn down or when the holding surface is ground to adjust the shape of the holding surface. In particular, in a grinding device, self-grinding is performed to grind the holding surface to adjust the shape of the holding surface or to remove processing debris that has accumulated on the holding surface (see, for example, Patent Document 1), but the height of the holding surface decreases due to self-grinding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-062048 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, the height at which the transport arm that transports the substrate within the processing device transfers the substrate to the holding surface of the holding table is set to a fixed value. Therefore, if the holding surface is ground and the height of the holding surface drops, the transport arm may not be able to properly transfer the substrate to the holding surface.

[0005] In particular, in the case of a substrate that is warped toward the periphery, if the substrate is not held by suction on the holding surface while pressed against the holding surface, a vacuum leak will occur and the substrate will not be held properly. In other words, if the height of the holding surface is lower than it was initially, but the transfer height at which the transport arm places the substrate on the holding surface is constant, the substrate will not be pressed properly against the holding surface, and the problem will arise that the holding table will not be able to hold the warped substrate by suction.

[0006] One method is to set the transfer height of the transport arm lower than necessary so that the substrate can be pressed against the holding surface even if the height of the holding surface is lowered, but this could result in the pressing force being too strong and damaging the substrate.

[0007] Therefore, in the substrate processing apparatus, there is a problem in that the substrate can be appropriately transported and transferred to the holding surface even if the height of the holding surface is lowered. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides: Protective tape is attached to the underside and the outer periphery is equipped with a warping element. A substrate processing apparatus comprising at least a holding table having a holding surface for holding a substrate, a height measuring unit for measuring the height of the holding surface, a transport arm for transporting the substrate relative to the holding table, a drive unit for lowering the transport arm to a transfer height at which the substrate is placed on the holding surface, and a control unit, the holding table includes a porous member having a diameter smaller than that of the protective tape, and a frame that surrounds and supports the porous member; the transport arm includes a holding pad that has an adsorption surface on its underside and holds a central region of the substrate, and an outer periphery pressing portion that surrounds the holding pad and presses the outer periphery of the substrate toward the holding surface; an annular accommodating groove is formed on the underside of the outer periphery pressing portion, and an O-ring is accommodated in the accommodating groove with its lower portion exposed from the accommodating groove; When the height of the holding surface is lowered, the control unit adjusts the height of the holding surface measured by the height measurement unit by a distance lowered from a previously recognized height of the holding surface. The substrate having the warping element was held Control is performed to lower the transfer height of the transfer arm. After the O-ring comes into contact with the warped outer periphery of the upper surface of the substrate, the transport arm further descends so that the suction surface, the lower surface of the O-ring, and the lower surface of the outer periphery pressing portion become flush with each other, and the exposed surface of the porous member is covered without any gaps by the protective tape on the lower surface of the substrate, eliminating vacuum leaks from the holding surface. A substrate processing apparatus. For example, the substrate processing apparatus may further include a grinding unit on which a grinding wheel for grinding the holding surface is rotatably mounted. Also It is preferable that the holding pad and the outer peripheral pressing portion are formed to include an elastic member. [Effects of the Invention]

[0009] In the substrate processing apparatus according to the present invention, even if the height of the holding surface of the holding table is lowered by a predetermined distance due to self-grinding or the like, the transfer arm also lowers the same distance to place the substrate on the holding surface and transfer it, preventing damage to the substrate during transfer to the holding surface. In particular, for warped substrates, a force is required to press the substrate against the holding surface. This is because the substrate is pressed against the holding surface and the holding surface applies suction to hold the substrate properly without vacuum leaks. However, if the height at which the transfer arm transfers the substrate is previously set low to prevent vacuum leaks even when the holding surface is lowered, the pressing force is too strong, which has traditionally led to damage. However, in the substrate processing apparatus according to the present invention, the transfer height is lowered in response to the lowering of the holding surface, eliminating the need to previously set the transfer position low due to concerns about vacuum leaks. The pressing force can be adjusted to an optimal level, eliminating this problem. In addition, the transport arm has a holding pad that holds the central region of the substrate, and an outer periphery pressing portion that surrounds the holding pad and presses the outer periphery of the substrate toward the holding surface, making it possible to more reliably suction-hold a warped substrate on the holding surface without vacuum leakage. Furthermore, by forming the holding pad and the outer peripheral pressing portion to include an elastic member, it becomes possible to further reduce the impact on the substrate when the substrate is transferred to and from the holding surface of the holding table. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing an example of a grinding device. [Figure 2] 10 is a cross-sectional view illustrating a state in which the substrate held by suction on the holding pad of the transport arm is positioned above the new holding table. FIG. [Figure 3] 10 is a cross-sectional view illustrating a state in which the transport arm, which holds the substrate by suction with the holding pad, is positioned at a transfer height at which the substrate is transferred to the holding surface of the new holding table. FIG. [Figure 4]10 is a cross-sectional view illustrating a state in which the height of the holding surface of the holding table after self-grinding is measured by a height measuring unit. FIG. [Figure 5] FIG. 10 is a cross-sectional view illustrating a state in which the substrate held by suction on the holding pad of the transport arm is positioned above the holding table after self-grinding. [Figure 6] 10 is a cross-sectional view illustrating a state in which the transfer arm, which holds the substrate by suction with the holding pad, is positioned at a corrected transfer height at which the substrate is transferred to the holding surface of the holding table after self-grinding. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1, for example, a substrate 90 made of silicon has an upper surface 900 molded with epoxy resin or the like. The substrate 90, which is circular in plan view, is warped and curved as a whole due to the contraction force of the molding resin or the like. That is, as shown in FIG. 2, the warp of the substrate 90 gradually increases from a central region 908 of a lower surface 902 of the substrate 90, which is held by suction, toward an outer peripheral region 907 (hereinafter referred to as the outer peripheral portion 907). The upper surface 900 of the substrate 90 is the surface to be ground, and a protective tape 91 is attached to the lower surface 902 of the substrate 90 to protect the lower surface 902. The substrate 90 is not limited to a silicon wafer, and may be made of gallium arsenide, sapphire, ceramics, resin, gallium nitride, silicon carbide, or the like. A device may or may not be formed on the lower surface 902 of the substrate 90. The substrate 90 does not have to have the above-described warpage. The warpage of the substrate 90 may be such that it gradually decreases from a central region 908 of the lower surface 902 of the substrate 90, which is held by suction, toward an outer periphery 907.

[0012] 1 is an apparatus that grinds a substrate 90 held on a holding table 30 using a grinding unit 41. The front (-Y direction side) of a base 10 of the substrate processing apparatus 1 is a loading / unloading area where the substrate 90 is loaded / unloaded onto / from the holding table 30, and the rear (+Y direction side) of the base 10 is a processing area where the grinding unit 41 performs grinding of the substrate 90 held on the holding table 30. The substrate processing apparatus 1 is a so-called fully automatic grinder. The substrate processing apparatus according to the present invention is not limited to a single-axis type grinding unit 41 like the substrate processing apparatus 1, but may be a grinding apparatus with two or more axes including a rough grinding unit and a finish grinding unit, and capable of positioning the substrate 90 below the rough grinding unit or the finish grinding unit using a rotating turntable. Alternatively, the substrate processing apparatus 1 may be a manual type grinding apparatus. Furthermore, the substrate processing apparatus 1 may be a polishing apparatus that polishes the substrate 90 with a polishing pad.

[0013] A first cassette stage 150 and a second cassette stage 151 are provided on the front side (-Y direction side) of the base 10, and a first cassette 157 in which a plurality of unprocessed substrates 90 are stored in a shelf-like manner is placed on the first cassette stage 150, and a second cassette 158 in which a plurality of processed substrates 90 are stored in a shelf-like manner is placed on the second cassette stage 151.

[0014] 1, the top of the base 10 is covered with a housing 100 that is formed with a viewing window through which an operator can view the inside, an access door for accessing the inside, etc. On the front surface on the -Y direction side of the housing 100, a touch panel 104 is provided that allows an operator to input processing conditions and setting data to a control unit 19 that controls each component of the substrate processing apparatus 1, and that can also display processing conditions, a layout diagram of each component of the apparatus, the state of the substrate 90, etc.

[0015] A robot 155 is disposed behind the opening on the +Y direction side of the first cassette 157, which unloads the unprocessed substrates 90 from the first cassette 157 and loads the processed substrates 90 into a second cassette 158. A temporary placement area 152 is provided adjacent to the robot 155, and an alignment unit 153 is disposed in the temporary placement area 152. The alignment unit 153 aligns (centers) the substrates 90, which have been unloaded from the first cassette 157 and placed in the temporary placement area 152, to a predetermined position using a diameter-reducing alignment pin.

[0016] A transfer arm 2, which is configured with a suction pad or the like and transfers the substrate 90 to the holding table 30, is disposed adjacent to the alignment unit 153. Next to the transfer arm 2, an unloading arm 29 is disposed, which unloads the substrate 90 from the holding table 30.

[0017] The transport arm 2 shown in Figures 1 and 2 comprises an arm bar 22 that extends parallel to the horizontal direction and has a holding pad 20 attached to the underside of its tip, a pivot shaft portion 24 whose axial direction is the Z-axis direction and which rotates the arm bar 22 horizontally, the holding pad 20 that uses its underside to suction and hold, for example, a central region 908 (see Figure 2) of the upper surface 900 of the substrate 90, and an outer periphery pressing portion 25 that surrounds the holding pad 20 and presses the outer periphery 907 of the substrate 90 toward the holding surface.

[0018] 2, a pad support plate 220 having a circular plate shape in plan view is fixed with bolts, for example, to the lower surface of the distal end side of arm bar 22. A coil spring 204, which is an elastic member for absorbing impact when it comes into contact with substrate 90, is attached to the center of pad support plate 220 so as to be expandable and contractible in the Z-axis direction. Note that a rubber pillar may be used as an elastic member instead of coil spring 204.

[0019] 2 is formed to have a smaller diameter than the substrate 90, and its flat lower surface serves as an adsorption surface 200 made of a porous material such as porous alumina. The adsorption surface 200 is connected to a suction source 209 such as a vacuum generator via a flexible resin tube or joint (not shown) that is flexible so as not to interfere with the movement of the transfer arm 2. The holding pad 20 may be a suction cup made of a deformable elastic material such as rubber and formed into a circular shape in a plan view, and in this case, a suction hole is formed at the center thereof so as to penetrate in the thickness direction. The suction hole may be connected to the suction source 209.

[0020] The lower surface of the circular plate-shaped pad support plate 220 has, for example, an outer peripheral region that protrudes downward in an annular shape relative to the central region, forming an annular protruding portion 251 that constitutes the outer periphery pressing portion 25. An annular accommodating groove 254 is cut out of the lower surface of the annular protruding portion 251. The accommodating groove 254 has, for example, an inverted trapezoidal cross section, and accommodates an O-ring 255, which is an annular elastic member. The O-ring 255 is formed with a thickness greater than the opening width of the accommodating groove 254 and is accommodated in the accommodating groove 254 so as not to fall out of the accommodating groove 254. The O-ring 255 is crushable and deformable within the accommodating groove 254, and a portion of its lower side is exposed downward from the accommodating groove 254.

[0021] 1, a drive unit 28 is connected to the lower end of the pivot shaft 24. The drive unit 28 is, for example, an electric cylinder including a servo motor, a ball screw, an encoder, etc., and lowers the transfer arm 2 in the Z-axis direction to a transfer height at which the substrate 90 is placed on the holding surface 302 of the holding table 30. The drive unit 28 also raises the transfer arm 2.

[0022] As shown in Figure 1, a single-wafer spinner cleaning mechanism 156 is disposed in the vicinity of the unloading arm 29, which cleans the processed substrate 90 transported by the unloading arm 29. The spinner cleaning mechanism 156 holds the protective tape 91 side of the substrate 90 on a spinner table, and sprays cleaning water onto the upper surface 802 of the substrate 90 from a swivel nozzle that can swivel above the held substrate 90 to clean it. The substrate 90 is then dried, for example, by spraying air from the swivel nozzle. The substrate 90 that has been cleaned and dried by the spinner cleaning mechanism 156 is transported into a second cassette 158 by a robot 155.

[0023] 1, a column 11 is erected on the rear side of the base 10, and a vertical movement unit 43 is disposed on the front surface of the column 11 on the -Y direction side, which moves the grinding unit 41 in the up and down direction (Z-axis direction) perpendicular to the holding surface 302 of the holding table 30. The vertical movement unit 43 is composed of a ball screw 430 whose axial direction is the Z-axis direction, a pair of guide rails 431 extending parallel to the ball screw 430, a motor 432 connected to the ball screw 430 and rotating the ball screw 430, and a lift plate 433 whose internal nut is threaded onto the ball screw 430 and whose sides are in sliding contact with the pair of guide rails 431. When the motor 432 rotates the ball screw 430, the lift plate 433 is guided by the guide rails 431 and moves back and forth in the Z-axis direction, and the grinding unit 41 attached to the lift plate 433 also moves back and forth in the Z-axis direction.

[0024] The grinding unit 41, which grinds the substrate 90 held by the holding surface 302 of the holding table 30, comprises a rotating shaft 410 whose axial direction is the Z-axis direction, a housing 411 that rotatably supports the rotating shaft 410 by an air bearing or the like formed inside, a motor 412 that rotates and drives the rotating shaft 410, a disk-shaped mount 413 connected to the lower end of the rotating shaft 410, a grinding wheel 414 that is detachably attached to the underside of the mount 413, and a holder 415 that supports the housing 411 and is connected to the lifting plate 433.

[0025] The grinding wheel 414 includes a wheel base 416 and a plurality of roughly rectangular parallelepiped-shaped segment grinding wheels arranged in a ring shape on the bottom surface of the wheel base 416. The segments are formed by, for example, fixing diamond abrasive grains with a resin bond, a vitrified bond, or the like. The plurality of segments arranged in a ring shape form a ring-shaped grinding wheel 417. It is also possible to arrange a ring-shaped grinding wheel with no gaps, i.e., a so-called continuous arrangement grinding wheel, on the underside of the wheel base 416.

[0026] Inside the rotating shaft 410, a flow path (not shown) that is connected to a grinding water supply source and serves as a passage for grinding water is provided, penetrating the axial direction of the rotating shaft 410, and the flow path further passes through the mount 413 and opens at the bottom of the wheel base 416 so that grinding water can be sprayed toward the annular grinding wheel 417.

[0027] The holding table 30 shown in FIG. 1 has, for example, a circular outer shape and includes a circular plate-like porous member 300 that adsorbs the substrate 90, and a frame 301 made of ceramics or the like that surrounds and supports the porous member 300. The porous member 300 is connected to a suction source (not shown) such as a vacuum generator. The suction force generated by the operation of the suction source (not shown) is transmitted to a holding surface 302 that is made up of the exposed surface of the porous member 300 and the upper surface of the frame 301 that is formed flush with the exposed surface, and the holding table 30 holds the substrate 90 on the holding surface 302 by suction. The holding surface 302 is a very gently sloping cone with its apex at the center of rotation of the holding table 30, so that it is indistinguishable from the naked eye.

[0028] As shown in FIG. 1, the holding table 30 is surrounded by a cover 39, and can be moved back and forth in the Y-axis direction on the base 10 by a Y-axis moving unit (not shown), such as an electric slider, arranged under the cover 39 and a bellows cover 390 connected to the cover 39 and extending and contracting in the Y-axis direction.

[0029] A thickness measurement unit 38 that contact-measures the thickness of the substrate 90 during grinding is disposed in the vicinity of the grinding wheel 414 that has been lowered to the height required for grinding the substrate 90. The thickness measurement unit 38 includes, for example, a pair of thickness measuring devices (height gauges), that is, a height measurement unit 381 for measuring the height of the holding surface 302 that is the upper surface of the holding table 30, and a substrate height measurement unit 382 for measuring the height of the upper surface 900 of the substrate 90 held by the holding table 30.

[0030] The height measurement unit 381 and the substrate height measurement unit 382 each have a contact at the tip that moves up and down and contacts each measurement surface. The height measurement unit 381 (substrate height measurement unit 382) is supported so that it can move up and down and can be pressed against each measurement surface with an appropriate force. The thickness measurement unit 38 detects the height of the holding surface 302, which serves as a reference surface, using the height measurement unit 381, and detects the height of the upper surface 900 of the substrate 90 to be ground using the substrate height measurement unit 382. By calculating the difference between the two detected values, the thickness of the substrate 90 can be measured sequentially during grinding. The thickness measurement unit 38 may also be a non-contact thickness measurement means.

[0031] The substrate processing apparatus 1 includes a control unit 19 that controls at least the drive unit 28. The control unit 19 includes a CPU that performs calculations according to a control program, a storage unit 190 such as a memory, and the like. The control unit 19 is electrically connected to the servo motor of the drive unit 28, which is, for example, an electric cylinder, via, for example, a wired or wireless communication path. That is, an output interface of the control unit 19, which also functions as a servo amplifier, supplies an operation signal to the servo motor of the drive unit 28, and the number of rotations of the servo motor detected by an encoder is output as an encoder signal to the input interface of the control unit 19. The control unit 19 then receives the number of rotations of the servo motor as an encoder signal, and can accurately position the transport arm 2, which is raised and lowered by the drive unit 28, to a desired height in the Z-axis direction. The motor of the drive unit 28 may be a pulse motor (stepping motor), and the control unit 19 may control the height of the transport arm 2 by counting the number of pulse signals sent to each pulse motor from a pulse oscillator (not shown).

[0032] The operation of the substrate processing apparatus 1 shown in FIG. 1 when grinding, for example, a new substrate 90 held on the holding table 30 having a predetermined thickness will be described below. First, the robot 155 takes out one substrate 90 from the first cassette 157 and moves the substrate 90 to the temporary placement area 152 .

[0033] After the substrate 90 is centered on the temporary placement area 152 by the alignment unit 153, the transport arm 2 suction-holds the central area 908 of the upper surface 900 of the substrate 90 shown in Figure 2 and transports it onto the holding table 30, and aligns the holding table 30 and the substrate 90 in the horizontal direction on the holding surface 302 so that the holding surface 302 of the holding table 30 and the center of the substrate 90 approximately coincide with each other.

[0034] For example, information about the height Z1 of the holding surface 302 of a brand new holding table 30 shown in Fig. 3 is input to the control unit 19 by an operator in advance and stored in the memory unit 190 of the control unit 19. Therefore, under the control of the drive unit 28 by the control unit 19, the transfer arm 2 is lowered to a height Z2 (transfer height Z2) that the control unit 19 has previously determined to correspond to the height Z1 of the holding surface 302. The transfer height Z2 is a height that has been determined experimentally, empirically, or theoretically so that the substrate 90 can be pressed against the holding surface 302 without being damaged and so that a vacuum leak from the holding surface 302 does not occur when the warped substrate 90 has been transferred to the holding surface 302.

[0035] 3, the transfer arm 2 is lowered at a predetermined speed by the drive unit 28 under the control of the control unit 19. Then, the central region of the lower surface of the protective tape 91 on the lower surface 902 of the substrate 90, which is held by suction by the holding pad 20 of the transfer arm 2, first comes into contact with the holding surface 302 of the holding table 30. Furthermore, the coil spring 204, which is an elastic member, contracts to absorb the impact when the substrate 90 comes into contact with the holding surface 302.

[0036] Furthermore, the O-ring 255 constituting the outer periphery pressing portion 25 comes into contact with the warped outer periphery 907 of the upper surface 900 of the substrate 90, pressing the outer periphery 907 downward toward the holding surface 302 and deforming it so as to be crushed. Then, when the transfer arm 2 descends to the delivery height Z2 previously recognized by the control unit 19, for example, the suction surface 200 of the holding pad 20, the lower surface of the O-ring 255, and the lower surface of the annular protrusion 251 become flush or nearly flush with each other, and when the outer periphery 907 of the substrate 90, which has a warped element, comes into contact with the upper surface of the frame 301, the exposed surface of the porous member 300 is tightly covered by the protective tape 91 on the lower surface 902 of the substrate 90, eliminating vacuum leaks from the holding surface 302.

[0037] Next, the suction force generated by the operation of a suction source (not shown) is transmitted to a holding surface 302 consisting of the exposed surface of the porous member 300 and the upper surface of the frame body 301 formed flush with the exposed surface, and the holding table 30 suction-holds the substrate 90 on the holding surface 302 without vacuum leakage.

[0038] Holding table 30 holding substrate 90 is moved in the +Y direction by a Y-axis movement unit (not shown) to below grinding unit 41. Then, the center of rotation of grinding wheel 417 of grinding unit 41 is shifted by a predetermined distance in the horizontal direction relative to the center of rotation of substrate 90, and grinding wheel 417 is positioned so that its rotational path passes through the center of rotation of substrate 90.

[0039] The motor 412 rotates the rotary shaft 410 at a predetermined rotational speed, which in turn rotates the grinding wheel 414. The grinding unit 41 is then moved in the −Z direction by the vertical movement unit 43, and the rotating grinding wheel 417 comes into contact with the upper surface 900 of the substrate 90, thereby performing grinding. During grinding, the holding table 30 rotates at a predetermined rotational speed, causing the substrate 90 held on the holding surface 302 to also rotate, so that the grinding wheel 417 grinds the entire upper surface 900 of the substrate 90. Grinding water is also supplied to the contact area between the grinding wheel 417 and the substrate 90 to cool and clean the contact area. After the substrate 90 has been ground to the desired thickness, the vertical movement unit 43 lifts the grinding unit 41 upward, and the grinding wheel 417 moves away from the substrate 90, completing the grinding process.

[0040] After the substrate 90 has been ground to the desired thickness, the holding table 30 is moved in the -Y direction and positioned near the unloading arm 29. Next, the substrate 90, which is held by suction by the unloading arm 29, is transported to the spinner cleaning mechanism 156. After the upper surface 900 of the substrate 90 is spin-cleaned by the spinner cleaning mechanism 156, the substrate 90 is air-dried or spin-dried. Thereafter, the substrate 90 is loaded into a second cassette 158 by the robot 155.

[0041] For example, when the above-described grinding process is performed successively on a plurality of substrates 90 one by one, grinding debris may become clogged on the holding surface 302 of the holding table 30, resulting in a decrease in the thickness accuracy of the ground substrates 90. Therefore, after grinding of a certain substrate 90 is completed and before grinding of the next new substrate 90, self-grinding is performed to grind the holding surface 302 to adjust the shape and to remove grinding debris from the holding surface 302.

[0042] The holding table 30 not holding the substrate 90 shown in FIG. 1 is moved in the +Y direction to below the grinding unit 41. The center of rotation of the grinding wheel 414 is then shifted horizontally by a predetermined distance relative to the center of rotation of the holding surface 302, so that the rotational path of the grinding wheel 417 passes through the center of rotation of the holding surface 302. To form the holding surface 302 into a desired shape, if necessary, the outer periphery of the holding table 30 may be slightly raised by a tilt adjustment means (not shown), thereby tilting the holding surface 302 of the holding table 30 and the lower surface of the grinding wheel 417 of the grinding unit 41 by a predetermined angle relative to each other. Before performing self-grinding, it is preferable to remove the grinding wheel 414 used to grind the substrate 90 and replace it with another grinding wheel suitable for grinding the holding surface 302.

[0043] Next, while the holding table 30 rotates, the vertical movement unit 43 lowers the grinding unit 41 at a predetermined grinding feed rate. The rotating grinding wheel 417 presses and grinds the holding surface 302, which is composed of the upper surface of the porous member 300 and the upper surface of the frame 301. The grinding wheel 417 constantly passes through the center of the holding surface 302, grinding the entire surface of the holding surface 302. After the grinding is performed for a predetermined time, the grinding unit 41 moves in the +Z direction and separates from the holding table 30. The holding surface 302 then assumes an extremely gentle conical shape, invisible to the naked eye, with its apex at the center of rotation of the holding surface 302 and sloping outward, completing self-grinding. The amount of self-grinding may be controlled by time or by detecting the height of the holding surface 302 using the height measurement unit 381 (in this embodiment, the height of the upper surface of the frame 301, which constitutes the holding surface 302 and is flush with the exposed surface of the porous member 300).

[0044] 4, the height measuring unit 381 measures the height of the holding surface 302 after self-grinding (in this embodiment, the height of the upper surface of the frame 301, which is flush with the holding surface 302). Here, by having the height measuring unit 381 measure the height of the upper surface of the frame 301, the exposed surface (upper surface) of the porous member 300 that suction-holds the substrate 90 is not damaged. The height of the holding surface 302 after grinding, measured by the height measuring unit 381, is assumed to be height Z3.

[0045] The height measurement unit 381 sends the measurement information to the control unit 19 shown in Figure 1, and the control unit 19 calculates the difference between the height Z1 of the holding surface 302 before grinding, which is stored in the memory unit 190 and recognized in advance, and the height Z3 of the holding surface 302 after self-grinding, as the distance L1 by which the height of the holding surface 302 has dropped.

[0046] 1 pulls out one substrate 90 from the first cassette 157, and the substrate 90 moves to the temporary placement area 152 and is centered. Thereafter, as shown in Fig. 5, the transfer arm 2 suction-holds the central area 908 of the upper surface 900 of the substrate 90 with the holding pad 20, and then transfers the substrate 90 onto the holding table 30, and aligns the substrate 90 in the horizontal direction so that the holding surface 302 of the holding table 30 and the center of the substrate 90 approximately coincide with each other.

[0047] Next, under the control of the drive unit 28 by the control unit 19, the transfer arm 2 is lowered to a height Z4 corresponding to the height Z3 of the holding surface 302 after grinding, i.e., a height Z4 (hereinafter referred to as the corrected transfer height Z4) that is lower than the previously determined transfer height Z2 by a distance L1. Specifically, as shown in FIG. 6 , under the control of the drive unit 28 by the control unit 19, the drive unit 28 lowers the transfer arm 2 at a predetermined speed. Then, the central region of the lower surface of the protective tape 91 on the lower surface 902 of the substrate 90, which is suction-held by the holding pad 20 of the transfer arm 2, first comes into contact with the holding surface 302 of the holding table 30. Furthermore, the coil spring 204 contracts to absorb the impact when the substrate 90 comes into contact with the holding surface 302. Furthermore, the O-ring 255 comes into contact with the warped outer periphery 907 of the upper surface 900 of the substrate 90, pressing the outer periphery 907 downward toward the holding surface 302 and deforming it. Then, by lowering the transfer arm 2 to the corrected transfer height Z4, the suction surface 200 of the holding pad 20, the lower surface of the O-ring 255, and the lower surface of the annular protrusion 251 become flush or nearly flush with each other, and the outer periphery 907 of the substrate 90, which has a warping element, comes into contact with the upper surface of the frame 301, so that the exposed surface of the porous member 300 is completely covered by the protective tape 91 on the lower surface 902 of the substrate 90, eliminating vacuum leakage from the holding surface 302. Here, the control unit 19 controls the transfer height to be lowered from the transfer height Z2 shown in FIG. 6 to the corrected transfer height Z4, so that the holding surface 302 corrects the warpage of the substrate 90, while the transfer arm 2 does not apply excessive pressure to the substrate 90 that could damage the substrate 90.

[0048] Next, the holding table 30 suction-holds the substrate 90 on the holding surface 302 to which the suction force has been transmitted without any vacuum leakage. Thereafter, the substrate 90 is ground in the same manner as described above.

[0049] In this way, in the substrate processing apparatus 1 according to the present invention, when the height of the holding surface 302 drops, the control unit 19 controls the transfer height of the transport arm 2 to drop by the distance L1 that the height Z3 of the holding surface 302 measured by the height measurement unit 381 has dropped from the previously recognized height Z1 of the holding surface 302. Therefore, even if the height of the holding surface 302 of the holding table 30 drops due to self-grinding or the like, the transport arm 2 also drops by the same distance L1 that the height of the holding surface 302 has dropped, and the substrate 90 is placed on the holding surface 302 for transfer, so that the substrate 90 is not damaged when being transferred to the holding surface 302. In particular, in the case of a warped substrate 90 as in this embodiment, a force is required to press the substrate 90 against the holding surface 302 to prevent vacuum leaks. Conventionally, if the height at which the transport arm 2 transfers the substrate 90 is set low in advance, the pressing force is too great and the substrate 90 is likely to be damaged. However, the substrate processing apparatus 1 according to the present invention can adjust the pressing force to an optimum level, preventing damage to the substrate 90.

[0050] In addition, the transport arm 2 has a holding pad 20 that holds the central region 908 of the substrate 90, and an outer periphery pressing portion 25 that surrounds the holding pad 20 and presses the outer periphery 907 of the substrate 90 toward the holding surface 302, making it possible to more reliably suction-hold a warped substrate 90 on the holding surface 302 without vacuum leakage.

[0051] Furthermore, the holding pad 20 is provided with an elastic member such as a coil spring 204, and the outer peripheral pressing portion 25 is provided with an elastic member such as an O-ring 255, which makes it possible to further reduce the impact on the substrate 90 when the substrate 90 is transferred to the holding surface 302 of the holding table 30.

[0052] The substrate processing apparatus 1 according to the present invention is not limited to the above embodiment, and may be embodied in various different forms within the scope of the technical concept thereof. Furthermore, the process of grinding the substrate 90 using the substrate processing apparatus 1 can also be modified as appropriate within the scope of the effects of the present invention. [Explanation of symbols]

[0053] 1: substrate processing apparatus 10: base 100: housing 150: First cassette stage 151: Second cassette stage 152: Temporary placement area 153: Alignment unit 155: Robot 19: Control unit 190: Memory unit 2: Transfer arm 20: Holding pad 204: Coil spring 209: Suction source 22: Arm bar 220: Pad support plate 24: Swivel shaft 25: Outer peripheral pressing portion 251: Annular protrusion 254: Receiving groove 255: O-ring 28: Drive unit 29: Discharge arm 30: Holding table 300: Porous member 301: Frame 302: Holding surface 38: Thickness measurement unit 381: Height measurement section 382: Substrate height measurement section 41: Grinding unit 43: Vertical movement unit 90: Substrate 900: Upper surface of substrate 902: Lower surface of substrate 907 Periphery 908: Central region 91: Protective tape

Claims

1. A substrate processing apparatus comprising at least a holding table having a holding surface for holding a substrate having a protective tape attached to its underside and having an element whose outer periphery is warped up, a height measuring unit for measuring the height of the holding surface, a transport arm for transporting the substrate relative to the holding table, a drive unit for lowering the transport arm to a transfer height at which the substrate is placed on the holding surface, and a control unit, the holding table includes a porous member having a diameter smaller than that of the protective tape, and a frame that surrounds and supports the porous member; the transport arm has a holding pad having an adsorption surface on its underside and holding a central region of the substrate, and an outer periphery pressing portion surrounding the holding pad and pressing the outer periphery of the substrate against the holding surface, an annular accommodating groove is formed on the underside of the outer periphery pressing portion, and an O-ring is accommodated in the accommodating groove with its lower portion exposed from the accommodating groove; When the height of the holding surface decreases, the control unit controls the transfer height of the transport arm holding the substrate having the warping element to decrease by the distance that the height of the holding surface measured by the height measuring unit has decreased from the previously recognized height of the holding surface.After the O-ring comes into contact with the warped outer periphery of the upper surface of the substrate, the transport arm further decreases, so that the suction surface, the lower surface of the O-ring, and the lower surface of the outer periphery pressing unit become flush, and the exposed surface of the porous member is tightly covered by the protective tape on the underside of the substrate, eliminating vacuum leaks from the holding surface.

2. 2. The substrate processing apparatus according to claim 1, further comprising a grinding unit on which a grinding wheel for grinding the holding surface is rotatably mounted.

3. 2. The substrate processing apparatus according to claim 1, wherein the holding pad and the outer periphery pressing portion are formed to include an elastic member.

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