Wafer cleaning device, processing apparatus, and processing method

Abstract

To provide a wafer cleaning device which can be compactly installed in a processing apparatus for a wafer.SOLUTION: A wafer cleaning device 50 comprises: a holding pad 51 which holds a top face of a wafer W; a cleaning mechanism 60 which cleans a part of a bottom face of the wafer W which is held by the holding pad 51; and a movement mechanism (such as a swing mechanism 70 and a Y-axis movement mechanism 80) 70 which relatively moves the holding pad 51 and the cleaning mechanism 60 in a horizontal direction. The cleaning mechanism 60 includes: a cleaning tub 61 of which the top face is opened and in which cleaning water is stored; a cleaning water supply part (such as a cleaning water supply source 64) 62 which supplies cleaning water to the cleaning tub 61; and an ultrasonic vibrator 63 which is disposed in the cleaning tub 61 and propagates ultrasonic vibration to the cleaning water. A part of the bottom face of the wafer W which is held by the holding pad 51 is landed on the cleaning water in the opening of the cleaning tub 61, so that the portion to be cleaned is spread over the entire bottom face of the wafer W by moving the holding pad 51 by the movement mechanism 70.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a wafer cleaning apparatus that cleans the underside of a wafer held on a holding pad. [Background technology]

[0002] Wafers are ground with a grinding wheel to a uniform thickness, but before grinding, the wafer may have foreign matter such as dust (hereinafter referred to as "particles") attached to it.When such a wafer is held on a chuck table, the particles become trapped between the wafer and the holding surface of the chuck table, causing the wafer to become thinner at the locations where the particles are present, resulting in the problem that the wafer cannot be made to a uniform thickness after grinding.

[0003] Therefore, Patent Document 1 proposes a cleaning device that brings a rotating roll sponge into contact with the underside of a wafer before it is held on a chuck table, and uses the roll sponge to remove particles adhering to the underside of the wafer, thereby cleaning the underside of the wafer.

[0004] However, the above cleaning apparatus has a problem in that the underside of the wafer is damaged by particles adhering to the roll sponge. For this reason, Patent Document 2 proposes a cleaning apparatus that houses a brush in a cleaning tank and brings the underside of the wafer into contact with the water surface raised by the surface tension of cleaning water stored in the cleaning tank, thereby removing particles adhering to the underside of the wafer. Furthermore, Patent Documents 3 and 4 propose ultrasonic cleaning apparatuses that use ultrasonic vibrations of cleaning water to remove particles adhering to the underside of the wafer in a non-contact manner. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-034439 [Patent Document 2] Japanese Patent Application Publication No. 2020-115496 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-363368 [Patent Document 4] Japanese Patent Publication No. 2023-084785 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the cleaning devices proposed in Patent Documents 2 to 4 require the cleaning tank to be large in order to accommodate the entire objects to be cleaned, such as brushes and wafers, and therefore the cleaning device is large in size. Therefore, the cleaning device cannot be installed compactly within the processing device, which results in a problem of the processing device being large in size.

[0007] SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a wafer cleaning apparatus that can be installed compactly in a wafer processing apparatus. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a wafer cleaning apparatus for cleaning the entire underside of a wafer, comprising: a holding pad for holding the upper surface of a wafer; a cleaning mechanism for cleaning a portion of the underside of the wafer held on the holding pad; and a moving mechanism for moving the holding pad and the cleaning mechanism relative to each other in a horizontal direction. The cleaning mechanism comprises a cleaning tank having an open upper surface and storing cleaning water therein so that the cleaning water rises above the opening; a cleaning water supply unit for supplying cleaning water to the cleaning tank; and an ultrasonic vibrator disposed in the cleaning tank for propagating ultrasonic vibrations to the cleaning water. The apparatus is characterized in that the portion to be cleaned by causing a portion of the underside of the wafer held on the holding pad to land in the cleaning water that rises above the opening of the cleaning tank is moved by the moving mechanism to cover the entire underside of the wafer. [Effects of the Invention]

[0009] According to the present invention, a portion of the wafer held on the holding pad is landed in the cleaning water stored in the cleaning tank, and the water is spread over the entire wafer by moving the wafer using the moving mechanism.In other words, the entire underside of the wafer is cleaned by scanning the wafer relative to the cleaning tank without immersing the entire wafer held on the holding pad in the cleaning water in the cleaning tank.This allows the cleaning tank to be made small and compact, and the wafer cleaning device to be installed compactly in the processing equipment. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a grinding apparatus equipped with a wafer cleaning apparatus according to the present invention; [Figure 2] 1 is a perspective view of a wafer cleaning apparatus according to the present invention; [Figure 3] 1 is a cutaway side view showing a wafer cleaning method using a wafer cleaning apparatus according to the present invention; [Figure 4] 1 is a plan view showing a wafer cleaning method using a wafer cleaning apparatus according to the present invention; [Figure 5] FIG. 1 is a partial side view showing the wafer grinding process. [Figure 6] FIG. 10 is a partial perspective view showing another embodiment of the wafer cleaning apparatus according to the present invention. [Figure 7] 10 is a cutaway side view showing a wafer cleaning method using a wafer cleaning apparatus according to another embodiment of the present invention. FIG. [Figure 8] 10A and 10B are plan views showing a wafer cleaning method using a wafer cleaning apparatus according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] [Grinding equipment configuration] First, the overall configuration of a grinding apparatus equipped with a wafer cleaning apparatus according to the present invention will be described with reference to Fig. 1. In the following description, the directions of the arrows shown in Fig. 1 will be referred to as the X-axis (left-right direction), the Y-axis (front-rear direction), and the Z-axis (up-down direction), respectively.

[0013] The grinding apparatus 1 shown in Figure 1 is an apparatus for grinding disk-shaped wafers W (see Figures 2 to 5), and includes as its main components two chuck tables 10 arranged on a rotatable disk-shaped turntable 2, a grinding unit 20 for grinding the wafers W held on the chuck tables 10, a cleaning unit 40 for cleaning the upper surfaces (surfaces to be ground) of the wafers W after grinding, and a wafer cleaning apparatus 50 according to the present invention for cleaning the entire lower surfaces of the wafers W.

[0014] The grinding apparatus 1 also includes, as other components, a first cassette 3 and a second cassette 4 arranged side by side along the X-axis direction (left-right direction) at the -Y-axis direction end (front end) of the base 100, a carry-in / out robot 5 arranged near the first cassette 3, and an alignment table 6 arranged near the carry-in / out robot 5. The first cassette 3 contains a plurality of wafers W before grinding, and the second cassette 4 contains a plurality of wafers W that have been ground and cleaned by the cleaning unit 40.

[0015] In this embodiment, the wafer W is made of a single-crystal silicon base material, but may be made of polycrystalline silicon. In addition to silicon (Si), the wafer W may be made of silicon carbide (SiC), glass, ceramics, sapphire (Al2O3), gallium arsenide (GaAs), or the like.

[0016] Next, the configurations of the chuck table 10, grinding unit 20, cleaning unit 40, and wafer cleaning apparatus 50 according to the present invention, which are the main components of the grinding apparatus 1, will be described.

[0017] (Chuck table) The two chuck tables 10, which are rotatably arranged on the turntable 2, are disk-shaped members and are arranged at equal angular pitches (180° pitches) in the circumferential direction on the turntable 2, which rotates intermittently around a central axis perpendicular to the Z-axis direction. These chuck tables 10 move sequentially between the wafer loading / unloading region R1 and the grinding region R2 as the turntable 2 rotates intermittently by half rotations (180° angle), and also rotate (spin) at a predetermined speed around a rotation axis CL1 (see FIG. 5) by a rotation mechanism (not shown).

[0018] 5, a disk-shaped porous member 10A made of porous ceramic or the like is mounted in the center of the upper part of each chuck table 10, and the upper surface of each porous member 10A forms a holding surface that suction-holds the wafer W. As shown in FIG. 5, each porous member 10A is selectively connected to a suction source 12 such as a vacuum pump via a pipe 11. That is, the porous member 10A is selectively connected to the suction source 12 by opening and closing an on-off valve V1 provided in the pipe 11.

[0019] (Grinding unit) The grinding unit 20 includes a holder 21 that is open at the top, a spindle motor 22 that is a rotational drive source that is fixed to the holder 21 in a vertically placed state, a spindle 23 that is rotationally driven by the spindle motor 22, a disk-shaped mount 24 attached to the lower end of the spindle 23, and a grinding wheel 25 that is detachably attached to the underside of the mount 24. Here, the grinding wheel 25 is composed of a disk-shaped base 25a and a plurality of grinding stones 25b that are attached in an annular shape to the underside of the base 25a.

[0020] The grinding unit 20 can be raised and lowered in the Z-axis direction (up and down direction) by a vertical movement mechanism 30, and this vertical movement mechanism 30 is disposed on the −Y-axis direction end face (front face) of a rectangular box-shaped column 110 that is erected vertically on the +Y-axis direction end face (rear end face) of the upper surface of the base 100. This vertical movement mechanism 30 raises and lowers a rectangular plate-shaped lift plate 31 attached to the back face of the holder 21 in the Z-axis direction along a pair of left and right guide rails 32 together with the holder 21 and the spindle motor 22, grinding wheel 25, etc. held by the holder 21. Here, the pair of left and right guide rails 32 are disposed perpendicular to the front face of the column 110 and parallel to each other.

[0021] A rotatable ball screw 33 is provided vertically along the Z-axis direction (up-down direction) between the pair of left and right guide rails 32, and the upper end of the ball screw 33 is connected to a motor 34, which serves as a drive source and can rotate forward and backward. The motor 34 is attached in an upright position via a rectangular plate-shaped bracket 35 attached to the upper surface of the column 110. The lower end of the ball screw 33 is rotatably supported by the column 110, and a nut member (not shown) that protrudes horizontally from the back surface of the lifting plate 31 toward the rear (+Y-axis direction) is threadedly engaged with the ball screw 33.

[0022] Therefore, when the motor 34 is started to rotate the ball screw 33 forward or backward, the lifting plate 31, to which a nut member (not shown) that screws onto the ball screw 33 is attached, moves up and down along the Z-axis together with the grinding unit 20.

[0023] When the wafer W is being ground by the grinding unit 20, grinding water is supplied from a grinding water supply source 26 to the contact area (grinding portion) between the grinding wheel 25b and the wafer W. The grinding water supply source 26 is connected via a pipe 27 to a supply path (not shown) formed vertically around the center of the axis of the spindle motor 22 of the grinding unit 20. The supply path formed in the spindle motor 22 is connected to supply paths (not shown) formed in the spindle 23, the mount 24, and the base 25a of the grinding wheel 25, respectively. The grinding water supplied from the grinding water supply source 26 is sprayed toward the inside of the grinding wheel 25b from multiple nozzles (not shown) formed in the base 25a. Pure water is preferably used as the grinding water. The pipe 27 is also provided with an on-off valve V2.

[0024] (Cleaning unit) The cleaning unit 40 cleans the grinding surface (upper surface) of the wafer W that has been ground by the grinding unit 20 to remove grinding debris and the like adhering to the grinding surface, and includes a spinner table 41 that holds and rotates the wafer W after grinding, and a cleaning water nozzle 42 that sprays cleaning water toward the upper surface, which is the grinding surface, of the wafer W. Note that pure water is preferably used as the cleaning water.

[0025] (Wafer cleaning equipment) The wafer cleaning apparatus 50 according to the present invention is an apparatus for cleaning the entire underside of a wafer W before removing the unground wafer W stored in the first cassette 3 and transferring the wafer W to the chuck table 10, and after the wafer W has been ground by the grinding unit 20, and is disposed at approximately the center of the base 100 in the Y-axis direction (front-rear direction) as shown in Fig. 1. The wafer cleaning apparatus 50 is composed of a disk-shaped holding pad 51 that holds the upper surface of the wafer W, a cleaning mechanism 60 that cleans the underside of the wafer W held by the holding pad 51, and a moving mechanism that moves the holding pad 51 horizontally relative to the cleaning mechanism 60.

[0026] The cleaning mechanism 60 is composed of an elongated cleaning tank 61 arranged along the X-axis direction between the alignment table 6 and the turntable 2 in the Y-axis direction on the base 100, a cleaning water supply unit 62 that supplies cleaning water to the cleaning tank 61, and an ultrasonic vibrator 63 installed on the underside of the cleaning tank 61. Here, the cleaning tank 61 is composed of a rectangular container that is elongated in the X-axis direction and has an open top, and the cleaning water supply unit 62 has a cleaning water supply source 64 that supplies cleaning water to the cleaning tank 61, and the cleaning water supply source 64 and the cleaning tank 61 are connected by a pipe 65. One end of this pipe 65 is connected to a plug 66 attached to the end face of the cleaning tank 61 in the +X-axis direction, and the pipe 65 is equipped with an on-off valve V3. Note that pure water is preferably used as the cleaning water.

[0027] The holding pad 51 can be oscillated in a horizontal plane by an oscillating mechanism 70 (see FIG. 2) described below, and can be moved horizontally along the Y-axis direction by a Y-axis moving mechanism 80 described below. The cleaning tank 61 is arranged along the X-axis direction, which is perpendicular to the arc-shaped oscillating path centered on the oscillating axis 52 (see FIG. 2) of the holding pad 51 and the linear path along the Y-axis direction, and extends along the X-axis direction by a length L1 (≧φD) that is longer than or equal to the diameter φD of the wafer W held on the holding pad 51 (see FIG. 4).

[0028] In addition, the ultrasonic vibrator 63 is composed of a piezoelectric element, such as a rectangular plate-shaped piezoelectric element that is long in the X-axis direction and attached to the underside of the cleaning tank 61, and is electrically connected to a power source 67 that applies high-frequency power to the ultrasonic vibrator 63.

[0029] 2, the holding pad 51 is a circular member attached to the tip of an arm 53 that is attached to the lower end of a vertical swing shaft 52 and extends horizontally. More specifically, a ring-shaped holding ring 54 is attached to the tip of the arm 53, and the holding pad 51 is suspended from this holding ring 54 via three pins 55. The lower surface of the holding pad 51 forms a holding surface, which is connected to a suction source 57 such as a vacuum pump via a pipe 56. An on-off valve V4 is attached to the pipe 56. Therefore, the suction surface of the holding pad 51 can be selectively connected to the suction source 57 by opening or closing the on-off valve V4.

[0030] 2, the vertical swing shaft 52 is inserted into a lift block 58 and can be rotated by a motor 59 attached to the upper surface of the lift block 58. Therefore, the motor 59 and the swing shaft 52 constitute a swing mechanism 70, and when the motor 59 is started and the swing shaft 52 rotates around its central axis, the arm 53 attached to the lower end of the swing shaft 52, the holding pad 51 supported on the tip of the arm 53, and the wafer W suction-held by the holding pad 51 as described below swing within a horizontal plane around the swing shaft 52.

[0031] The lifting block 58 can be raised and lowered in the Z-axis direction along the vertical guide rail 71 by a Z-axis movement mechanism 90 (see FIG. 3) together with the swing shaft 52, the arm 53, and the holding pad 51. The Z-axis movement mechanism 90 is configured by a known ball screw mechanism.

[0032] The movement mechanism that moves the holding pad 51 and the wafer W suction-held thereon in the horizontal direction relative to the cleaning mechanism 60 is composed of the swinging mechanism 70 and the Y-axis movement mechanism 80. Here, as shown in Fig. 1, the Y-axis movement mechanism 80 is provided on a rectangular support plate 82 that is supported vertically by a support column 81 at approximately the center of the base 100 in the Y-axis direction. Here, as shown in detail in Fig. 2, the Y-axis movement mechanism 80 provided on the support plate 82 includes a pair of upper and lower guide rails 83 that are arranged parallel to the Y-axis on the end surface of the support plate 82 in the +X-axis direction, and the slider 84 in the shape of a rectangular block that is movable in the Y-axis direction along the guide rails 83.

[0033] The slider 84 supports a lifting block 58 that can move up and down in the Z-axis direction along a guide rail 83, and therefore the swing mechanism 70, arm 53, holding pad 51, etc. can move along the Y-axis direction together with the slider 84.

[0034] In Y-axis movement mechanism 80, a rotatable ball screw 85 is arranged along the Y-axis direction between upper and lower guide rails 83, and this ball screw 85 is threadably inserted into slider 84. One end of ball screw 85 is rotatably supported by support plate 82 via bearing 86, and the other end of ball screw 85 is connected to motor 87, which serves as a drive source.

[0035] Therefore, when motor 87 is started to rotate ball screw 85 forward or backward, slider 84, into which ball screw 85 is threadedly inserted, can move along the Y-axis direction together with lift block 58, holding pad 51, and the like that constitute Z-axis movement mechanism 90. Therefore, holding pad 51 and wafer W held thereby can oscillate within a horizontal plane and can also move horizontally along the Y-axis direction.

[0036] [Function of grinding equipment] Next, the operation of the grinding device 1 configured as above will be described.

[0037] When grinding a wafer W in the grinding apparatus 1, an unprocessed wafer W is removed from the first cassette 3 by the transfer robot 5 shown in Fig. 1 and temporarily placed on the alignment table 6. The wafer W is then aligned (centered) on the alignment table 6, and the aligned wafer W is suction-held by the holding pad 51 and transported to the chuck table 10 located in the wafer transfer area R1, during which the entire bottom surface of the wafer W is cleaned by the wafer cleaning apparatus 50 according to the present invention, and particles P (see Fig. 3) adhering to the bottom surface are removed.

[0038] That is, the upper surface of the wafer W aligned (centered) on the alignment table 6 is suction-held by the holding pad 51. That is, when the on-off valve V4 is opened and the holding surface (lower surface) of the holding pad 51 is connected to the suction source 57 via the piping 56, a negative pressure is generated on the holding surface, and the wafer W is attracted by this negative pressure and held by suction on the holding surface of the holding pad 51 as shown in FIGS.

[0039] In wafer cleaning apparatus 50, cleaning tank 61 is filled with cleaning water supplied from cleaning water supply source 64, and the surface of the cleaning water rises in an arc due to surface tension and is located higher than the upper end surface of cleaning tank 61, as shown in Fig. 3. High-frequency power is applied from power source 67 to ultrasonic vibrator 63 attached to the lower surface of cleaning tank 61, and ultrasonic vibrator 63 ultrasonically vibrates the cleaning water in cleaning tank 61.

[0040] In the above state, when the holding pad 51 and the wafer W held thereby are moved horizontally in a straight line along the Y-axis direction by, for example, the Y-axis movement mechanism 80, and the holding pad 51 and the wafer W cross the cleaning tank 61 in the Y-axis direction perpendicular to the longitudinal direction (X-axis direction) as shown in Figures 2 and 3, that is, when the cleaning tank 61 scans the underside of the wafer W, the underside of the wafer W comes into contact (lands) with the upper surface of the cleaning water that has risen due to surface tension in the cleaning tank 61, and particles P adhering to the underside of the wafer W are removed by the cleaning water. In this case, since the cleaning water is ultrasonically vibrated by the ultrasonic vibrator 63, particles P adhering to the underside of the wafer W are reliably removed by the ultrasonically vibrated cleaning water.

[0041] Thus, in the wafer cleaning apparatus 50 according to the present invention, a portion of the wafer W held on the holding pad 51 is landed in the cleaning water stored in the cleaning tank 61, and the water landing of the wafer W is made to cover the entire wafer W by linearly moving the holding pad 51 by the Y-axis moving mechanism 80, which is a moving mechanism. In other words, the entire underside of the wafer W held on the holding pad 51 is cleaned by scanning the wafer W relative to the cleaning tank 61 without immersing the entire wafer W held on the holding pad 51 in the cleaning water in the cleaning tank 61. This allows the cleaning tank 61 to be made small and compact, and the wafer cleaning apparatus 50 to be made small and installed compactly in the grinding apparatus 1. That is, in this embodiment, as the wafer W crosses the cleaning tank 61, the impact of the cleaning water on a portion of the wafer W extends to the impact of the water on the entire wafer W, so the width B (see Figure 4) of the cleaning tank 61 can be set to the minimum necessary and sufficient value, making the cleaning tank 61 small and compact.As a result, the wafer cleaning apparatus 50 can be made small and installed compactly in the grinding apparatus 1.

[0042] In this embodiment, the wafer cleaning apparatus 50 cleans the entire underside of the wafer W while the Y-axis moving mechanism 80 moves the holding pad 51 and the wafer W held thereon horizontally and linearly in the Y-axis direction. However, the wafer W may be scanned across the cleaning tank 61 when the holding pad 51 and the wafer W held thereon are moved along an arc path centered on the oscillation axis 52 by the oscillation mechanism 70. That is, the cleaning tank 61 may be arranged to extend a length L1 (≧φD) equal to or greater than the diameter φD of the wafer W along the X-axis direction, which is perpendicular to the arc-shaped movement path of the holding pad 51 and the wafer W.

[0043] As described above, when the underside of the wafer W is cleaned by the wafer cleaning device 50, the wafer W held on the holding pad 51 is sucked and held on the holding surface of the chuck table 10 located in the wafer loading / unloading area R1 (see FIG. 1) with the cleaned underside facing down, as shown in FIG. 5. That is, when the on-off valve V1 opens, the porous member 10A of the chuck table 10 is connected to the suction source 12 via the piping 11, generating a negative pressure in the porous member 10A, and the wafer W is sucked and held on the holding surface of the chuck table 10, which is the upper surface of the porous member 10A, by this negative pressure.

[0044] As described above, when the wafer W is transported to the chuck table 10 located in the wafer loading / unloading area R1 and held by suction on the holding surface of the chuck table 10, the turntable 2 shown in Figure 1 rotates half a turn in the direction of the arrow, and the chuck table 10 and the wafer W held thereon move to the grinding area R2 and are positioned below the grinding wheel 25 of the grinding unit 20.

[0045] Then, the chuck table 10 is rotated together with the wafer W at a predetermined speed in the direction of the arrow shown in the figure around the rotation axis CL1 by a rotation mechanism not shown, and the grinding wheel 25 of the grinding unit 20 is rotated at a predetermined speed around the rotation axis CL2 by the spindle motor 22 with the grinding wheel 25 positioned so that the circumscribed circle of the grinding stone 25b passes through the center of the wafer W.

[0046] Then, when the grinding wheel 25 is lowered by the vertical movement mechanism 30 by a predetermined amount of grinding allowance from the above state, the upper surface of the wafer W is ground by the grinding stone 25b. After the upper surface of the wafer W is ground in this manner, the turntable 2 shown in FIG. 1 rotates half a turn in the direction of the arrow, and the chuck table 10 supported by the turntable 2 and the wafer W move R1 to the wafer transfer area. In grinding the wafer W, grinding water (pure water) is supplied from the grinding water supply source 26 to the contact area (grinding area) between the wafer W and the grinding stone 125b, and frictional heat generated at the contact area is removed by the grinding water, suppressing a temperature rise at the contact area, and grinding chips generated by grinding are washed away and removed by the grinding water.

[0047] As described above, after the wafer W is ground, the wafer W on the chuck table 10 is suction-held by the holding pad 51 and transported to the cleaning unit 40. During the process of transporting the wafer W to the cleaning unit 40, the underside of the wafer W is cleaned by the wafer cleaning device 50 in the same manner as described above, and grinding debris and the like adhering to the underside are removed.

[0048] 1 by holding pad 51, the wafer W whose underside has been cleaned by wafer cleaning device 50 is transferred to cleaning unit 40 shown in FIG. 1, where the wafer W is transferred to spinner table 41 and held on the holding surface of spinner table 41. Then, from this state, spinner table 41 rotates at high speed together with wafer W, and cleaning water is sprayed from cleaning water nozzle 42 toward the upper surface of wafer W, whereby grinding debris and the like adhering to the upper surface of wafer W are washed away and removed by the cleaning water.

[0049] As described above, the wafer W whose underside has been cleaned by the cleaning unit 40 is transferred from the spinner table 41 to the loading / unloading robot 5, which then transports it to the second cassette 4 and stores it in the second cassette 4, thereby completing the series of grinding processes on the wafer W.

[0050] [Another type of wafer cleaning device] Next, another embodiment of the wafer cleaning apparatus according to the present invention will be described with reference to Figures 6 to 8. In Figures 6 to 8, the same elements as those shown in Figures 2 to 4 are denoted by the same reference numerals, and a repeated description of these elements will be omitted below.

[0051] 6 to 8 show the configuration of the main parts of a wafer cleaning apparatus according to another embodiment. In this embodiment, a holding pad 51 is supported by a rotation mechanism at the tip of a horizontally extending arm 53 so as to be rotatable about a vertical axis. The rotation mechanism includes a motor 92, which serves as a rotation drive source, attached vertically to the tip of the arm 53 via a rotary joint 91. A spindle 68 is rotatably and vertically supported at the tip of the arm 53, and a holding pad 51 is attached horizontally to the lower end of the spindle 68. Therefore, by rotating the spindle 68 in the direction of the arrow in FIG. 7 by the motor 92, the holding pad 51 attached to the lower end of the spindle 68 and the wafer W held by it by suction rotate in the same direction.

[0052] 6 and 7, a pipe 56 is connected to the rotary joint 91 via a plug 69, and this pipe 56 is connected to a suction source 57 via an on-off valve V4. A suction path (not shown) is formed vertically in the center of the rotary joint 91, and this suction path is connected to the holding surface (lower surface) of the holding pad 51. Therefore, when the on-off valve V4 is opened to connect the suction surface of the holding pad 51 to the suction source 57, a negative pressure is generated on the holding surface of the holding pad 51, and the wafer W is attracted by this negative pressure and held by the holding pad 51, as shown in FIGS.

[0053] In this embodiment, a cleaning tank 61 in the shape of a rectangular container with an open top is disposed along the Y-axis direction, and this cleaning tank 61 extends in the Y-axis direction with a length L2 (≧r) that is equal to or greater than the radius r of the wafer W. The cleaning tank 61 is filled with cleaning water supplied from a cleaning water supply source 64 via a pipe 65, and the upper surface of this cleaning water rises due to surface tension and is located above the upper end of the cleaning tank 61, as shown in FIG.

[0054] In this embodiment, a rectangular flat ultrasonic vibrator 63 is attached to the underside of the cleaning tank 61, and a power source 67 is electrically connected to this ultrasonic vibrator 63 to apply high-frequency power to the ultrasonic vibrator 63.

[0055] In the wafer cleaning apparatus configured as described above, the holding pad 51 and the wafer W held thereon are moved horizontally in a straight line along the Y-axis direction by the Y-axis moving mechanism 80 from the position shown by the dotted line in Figures 7 and 8, and when these holding pad 51 and wafer W are positioned above the cleaning tank 61 and most of the cleaning tank 61 is covered by the wafer W, as shown by the solid line in Figures 7 and 8, the holding pad 51 and wafer W are lowered by the Z-axis moving mechanism 90 so that part of the underside of the wafer W comes into contact with the cleaning water in the cleaning tank 61.

[0056] Then, in the above state, when motor 92 is started to rotate holding pad 51 together with wafer W in the direction of the arrow in the drawing, the underside of wafer W is immersed in cleaning water in cleaning tank 61, from a portion of wafer W to the entire area, and as a result, the entire underside of wafer W is cleaned with cleaning water, and particles P (see FIG. 7) adhering to the underside are removed. That is, as wafer W rotates, cleaning tank 61 scans the underside of wafer W, and the entire underside of wafer W is cleaned with cleaning water. In this case, since the cleaning water is ultrasonically vibrated by ultrasonic vibrator 63, particles P adhering to the underside of wafer W are reliably removed by the ultrasonically vibrating cleaning water.

[0057] In the wafer cleaning apparatus according to this embodiment, a portion of the wafer W held on the holding pad 51 is immersed in cleaning water stored in the cleaning tank 61, and the rotation of the wafer W causes the water to reach the entire underside of the wafer W. In other words, the entire underside of the wafer W is cleaned by rotating the wafer W and scanning it relative to the cleaning tank 61 without immersing the entire wafer W held on the holding pad 51 in the cleaning water in the cleaning tank 61. This allows the width B of the cleaning tank 61 to be set to the minimum necessary value and the length L2 of the cleaning tank 61 to be shortened to a value slightly greater than the radius r of the wafer W, thereby making the cleaning tank 61 small and compact. As a result, the wafer cleaning apparatus can be made smaller, and the processing apparatus, such as a grinding apparatus, in which it is installed can also be made small and compact.

[0058] In this embodiment, the cleaning tank 61 is arranged along the Y-axis direction, but the same effect as above can be obtained even if the cleaning tank 61 is arranged along the X-axis direction as shown by the chain line in FIG.

[0059] In the above embodiment, a grinding apparatus equipped with the wafer cleaning apparatus of the present invention has been described, but the wafer cleaning apparatus of the present invention can be provided in any other processing apparatus such as a polishing apparatus or a cutting apparatus, and can contribute to making these processing apparatuses smaller and more compact.

[0060] Furthermore, the present invention is not limited to the application of the above-described embodiments, and it goes without saying that various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0061] 1: Grinding device, 2: Turntable, 3: First cassette, 4: Second cassette, 5: Loading / unloading robot, 6: Alignment table, 10: Chuck table, 10A: porous member, 11: piping, 12: suction source, 20: grinding unit, 21: holder, 22: spindle motor, 23: spindle, 24: mount, 25: grinding wheel, 25a: base, 25b: grinding wheel, 26: grinding water supply source, 27: piping, 30: vertical movement mechanism, 31: lifting plate, 32: guide rail, 33: ball screw, 34: motor, 35: bracket, 40: cleaning unit, 41: spinner table, 42: cleaning water nozzle, 50: wafer cleaning device, 51: holding pad, 52: swing shaft, 53: arm, 54: Retaining ring, 55: Pin, 56: Piping, 57: Suction source, 58: Lifting block, 59: plug, 60: cleaning mechanism, 61: cleaning tank, 62: cleaning water supply unit, 63: ultrasonic vibrator, 64: cleaning water supply source, 65: piping, 66: plug, 67: power supply, 68: spindle, 69: plug, 70: swing mechanism, 71: guide rail, 80: Y-axis movement mechanism, 81: support column, 82: support plate, 83: guide rail, 84: slider, 85: guide rail, 86: bearing, 87: motor, 90: Z-axis movement mechanism, 91: rotary joint, 92: motor, 100: base, 110: column, B: width of cleaning tank, CL1: rotation axis of chuck table, CL2: rotation axis of the spindle, φD: diameter of the wafer, L1, L2: length of the cleaning tank, R1: wafer loading / unloading area, R2: grinding area, r: wafer radius, V1 to V4: on-off valves, W: wafer

Claims

1. A wafer cleaning apparatus for cleaning the entire underside of a wafer, a holding pad for holding the upper surface of the wafer; a cleaning mechanism for cleaning a portion of the underside of the wafer held on the holding pad; a moving mechanism that moves the holding pad and the cleaning mechanism relative to each other in a horizontal direction; Equipped with The cleaning mechanism includes: a cleaning tank having an open top and storing cleaning water therein so that the water rises above the opening; a cleaning water supply unit that supplies cleaning water to the cleaning tank; an ultrasonic vibrator disposed in the cleaning tank for propagating ultrasonic vibrations to the cleaning water; Equipped with A wafer cleaning apparatus in which a portion of the underside of a wafer held on the holding pad is landed in the cleaning water rising above the opening of the cleaning tank, and the portion to be cleaned is caused to cover the entire underside of the wafer by moving the holding pad using the moving mechanism.

2. The movement mechanism is a mechanism that moves the holding pad horizontally along a linear or arcuate movement path, 2. The wafer cleaning apparatus according to claim 1, wherein the cleaning tank extends in a direction intersecting the moving path of the holding pad, the length of the cleaning tank being equal to or greater than the diameter of the wafer.

3. The moving mechanism is a mechanism for rotating the holding pad around an axis passing through the center of the holding pad, 2. The wafer cleaning apparatus according to claim 1, wherein the cleaning tank extends over a length equal to or greater than the radius of the wafer.

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