Processing device

Abstract

To provide a processing device capable of shortening the cleaning time of a wafer after polishing by removing polishing chips from the entire surface of the wafer during polishing.SOLUTION: A polishing device (processing device) 1 comprises a chuck table 10 that holds a wafer W with a conical holding surface, a polishing mechanism 30 that polishes the wafer W using a polishing pad 35, and a control unit 60. The polishing pad 35 has a ring-shaped polishing surface with an opening 35a in the central part. The chuck table 10 and the polishing pad 35 are relatively tilted so that a contact region of the holding surface of the chuck table 10 becomes parallel to the polishing surface of the polishing pad 35. The polishing mechanism 30 includes an air supply passage 51 with one end opening into the opening 35a of the polishing pad 35 and the other end connected to an air supply source 52, and an open / close valve V that opens / closes the air supply passage 51. The control unit 60 opens the open / close valve V when the pad comes into contact with the contact region W1 of the wafer W to polish the wafer W.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a processing apparatus including a polishing mechanism for polishing a wafer with a polishing pad.

Background Art

[0002] In the manufacturing process of semiconductor devices such as ICs and LSIs, in order to miniaturize and reduce the weight of the semiconductor devices, the back surface of the wafer is ground and the wafer is thinned to a predetermined thickness. This grinding of the wafer is performed by pressing a grinding wheel against the back surface (upper surface in the processing state) of the wafer while rotating the grinding wheel at high speed. When the back surface of the wafer is ground by such a grinding method, grinding marks remain on the back surface (ground surface) of the wafer, and these grinding marks cause a decrease in the flexural strength of the wafer.

[0003] Therefore, the back surface (ground surface) of the wafer is polished with a polishing pad by a polishing apparatus to remove the grinding marks. Here, as the polishing apparatus, there are a dry polishing apparatus that polishes the wafer without supplying slurry to the polishing area between the rotating polishing pad and the wafer (see, for example, Patent Documents 1 and 2), and a wet polishing apparatus that polishes the wafer while supplying slurry to the polishing area between the rotating polishing pad and the wafer (see, for example, Patent Document 3).

[0004] By the way, in the dry polishing apparatus, the polishing surface of the polishing pad larger than the wafer is pressed against the wafer to polish the upper surface of the wafer. During the polishing process, air is injected into the portion of the polishing pad protruding from the wafer to remove the polishing debris from the polishing pad and the wafer. That is, air is injected from an air nozzle disposed near the outer periphery of the chuck table holding the wafer into the portion of the polishing pad protruding from the wafer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, since the air jetted from the air nozzle does not reach the central portion of the wafer, the polishing debris in the central portion of the wafer is not removed, and the polishing debris accumulates in the central portion of the wafer. For this reason, there is a problem that it takes time to clean the wafer after polishing.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a processing apparatus capable of removing polishing debris from the entire surface of a wafer during polishing and shortening the cleaning time of the wafer after polishing.

Means for Solving the Problems

[0008] The present invention for solving the above problems is a processing apparatus including a chuck table that holds a wafer by a conical holding surface, a polishing mechanism that polishes the wafer held by the chuck table with a polishing pad attached to a spindle, and a control unit, wherein the polishing pad has an opening at a central portion and includes a ring-shaped polishing surface, the chuck table and the polishing pad are relatively inclined so that a contact region of the holding surface is parallel to the polishing surface of the polishing pad, the polishing mechanism includes an air supply path having one end opening to the opening of the polishing pad and the other end connected to an air supply source, and an opening / closing valve that opens and closes the air supply path, and the control unit is characterized in that the opening / closing valve is opened when the polishing surface of the polishing pad contacts a contact region of the wafer held by the chuck table and polishes the wafer.

Effects of the Invention

[0009] According to the present invention, a wafer held on a holding surface of a chuck table having a conical holding surface is polished by a rotating polishing pad while the chuck table is tilted by a predetermined angle relative to the polishing surface of the polishing pad. During grinding, air is supplied from an air supply source through an air supply passage to an opening formed at the center of the polishing pad, and the air is jetted from the opening toward the upper surface of the wafer. Therefore, a minute gap is formed between the non-contact region of the wafer where the polishing pad does not contact during polishing and the lower surface of the polishing pad. Thus, when air is jetted from the opening formed at the center of the polishing pad toward the upper surface of the wafer, polishing debris generated by polishing the wafer flows outward in the radial direction by the air and is discharged from the gap. In this case, since the wafer is rotating, the polishing debris is discharged out of the gap from the entire upper surface of the wafer and is surely removed, and the polishing debris does not remain at the center of the upper surface of the wafer as in the conventional case. As a result, the cleaning of the wafer performed after the polishing process can be carried out in a short time, and thus the effect of enhancing the productivity can be obtained.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

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

[0012] [Configuration of Polishing Apparatus] First, the overall configuration of a polishing apparatus as one form of the processing apparatus according to the present invention will be described with reference to FIG. 1. In the following description, the directions indicated by the arrows in FIG. 1 are taken as the X-axis direction (front-rear direction), Y-axis direction (left-right direction), and Z-axis direction (up-down direction), respectively.

[0013] The polishing apparatus 1 shown in FIG. 1 is an apparatus for polishing the upper surface of a thin disk-shaped wafer W (see FIG. 2) which is an object to be polished. The wafer W is composed of a thin disk-shaped substrate made of a single-crystalline silicon base material. The wafer W is held by a chuck table 10 on its lower surface, and after its upper surface is ground to a predetermined thickness by a grinding apparatus (not shown), the ground surface is polished by the polishing apparatus 1.

[0014] Thus, as shown in FIG. 1, the polishing apparatus 1 includes a chuck table 10 for holding the wafer W, a horizontal movement mechanism 20 for moving the chuck table 10 in the Y-axis direction (left-right direction), a polishing mechanism 30 for polishing the wafer W held by the chuck table 10, a lifting mechanism 40 for moving the polishing mechanism 30 up and down in the Z-axis direction (up-down direction), an air supply means 50 for supplying air toward the polishing area between the polishing pad 35 of the polishing mechanism 30 and the wafer W, and a control unit 60 for controlling each element as main components.

[0015] Here, the configurations of the main components constituting the polishing apparatus 1, namely, the chuck table 10, the horizontal movement mechanism 20, the polishing mechanism 30, the lifting mechanism 40, the air supply means 50, and the control unit 60, will be described respectively as follows.

[0016] (Chuck Table) As shown in Fig. 2, the chuck table 10 is configured by incorporating a disc-shaped porous member 11 in the central portion of a disc-shaped frame body 10A. Here, the porous member 11 is made of porous ceramic or the like, and the upper surface thereof exposed to the frame body 10A constitutes a holding surface for sucking and holding a disc-shaped wafer W.

[0017] By the way, as shown in Fig. 2, the upper surface of the porous member 11 constituting the holding surface of the chuck table 10 constitutes a conical holding surface that slopes obliquely downward toward the outer side in the radial direction with the center as the apex. The porous member is selectively connected to a suction source (not shown) such as a vacuum pump or an ejector.

[0018] Also, as shown in Fig. 2, the chuck table 10 includes a rotation mechanism 2 that rotationally drives the chuck table 10 at a predetermined speed around the rotation axis CL1 of the vertical table rotation axis 12. Here, as shown in Fig. 1, the rotation mechanism 2 includes a drive motor 4 vertically mounted on the side surface of a slider 21 (to be described later) of the horizontal movement mechanism 20 by a bracket 3, a small-diameter drive pulley 5 coupled to the output shaft of the drive motor 4, a large-diameter driven pulley 6 coupled to the table rotation axis 12, and an endless timing belt 7 wound around the drive pulley 5 and the driven pulley 6. An encoder 8 for detecting the rotation direction, rotation speed, etc. of the drive motor 4 is attached to the drive motor 4, and the encoder 8 and the drive motor 4 are electrically connected to the control unit 60.

[0019] Also, as shown in FIG. 1, between the flange 13 of the chuck table 10 and the slider 21, two actuators 14 and one pivot (not shown) that constitute an inclination adjustment mechanism for adjusting the inclination of the chuck table 10 are interposed at an equal angular pitch (120° pitch) in the circumferential direction. Therefore, the chuck table 10 is tilted about one pivot by the two actuators 14, and its inclination is adjusted as described later.

[0020] (Horizontal movement mechanism) As shown in FIG. 1, the polishing apparatus 1 includes a rectangular box-shaped base 70 that is long in the Y-axis direction (left and right direction). Inside this base 70, a rectangular block-shaped inner base 71 is accommodated. And on this inner base 71, a horizontal movement mechanism 20 for moving the chuck table 10 and the wafer W sucked and held on its holding surface along the Y-axis direction (left and right direction) is provided.

[0021] The horizontal movement mechanism 20 includes a block-shaped slider 21. This slider 21 is slidable in the Y-axis direction along a pair of front and rear guide rails 22 arranged in parallel to each other along the Y-axis direction (left and right direction). Therefore, the chuck table 10 supported by this slider 21 and the rotation mechanism 2 are slidable along the Y-axis direction together with the slider 21.

[0022] And between the pair of left and right guide rails 22 on the inner base 71, a rotatable ball screw 23 extending in the Y-axis direction (left and right direction) is disposed. One end (the left end in FIG. 1) of the ball screw 23 is connected to a servo motor 24 that can rotate forward and backward, which is a drive source. Also, the other end (the right end in FIG. 1) of the ball screw 23 is rotatably supported by the inner base 71 by a bearing 25 erected on the inner base 71. Note that a nut member (not shown) protruding downward from the slider 21 is screwed onto this ball screw 23.

[0023] Therefore, when the ball screw 23 is rotated forward and backward by the servo motor 24, a nut member (not shown) screwed onto the ball screw 23 slides along the ball screw 23 in the Y-axis direction (left and right direction) together with the slider 21. As a result, the chuck table 10 also moves integrally along the Y-axis direction together with the slider 21. Consequently, the wafer W, which is the object to be polished held on the holding surface of the chuck table 10, and the rotating mechanism 2 also move integrally along the Y-axis direction.

[0024] Also, as shown in FIG. 1, a rectangular opening 70a that is long in the Y-axis direction is formed on the upper surface of the base 70, and the chuck table 10 faces this opening 70a. The periphery of the chuck table 10 at the opening 70a that opens on the upper surface of the base 70 is covered by a rectangular plate-shaped cover 15. The left and right (-Y direction and +Y direction) portions of the cover 15 at the opening 70a are respectively covered by a pair of bellows-shaped expandable and contractible covers 16 and 17 that move and expand and contract together with the cover 15. Therefore, no matter what position the chuck table 10 is in the Y-axis direction, the opening 70a is always covered by the expandable and contractible covers 16 and 17, preventing foreign matter from entering the inside of the base 70 from the opening 70a.

[0025] (Polishing mechanism) The polishing mechanism 30 includes a spindle motor 32 fixed to a holder 31, a vertical spindle 33 rotationally driven by the spindle motor 32, a disk-shaped mount 34 attached to the lower end of the spindle 33, and a disk-shaped polishing pad 35 detachably mounted on the lower surface of the mount 34. Here, as shown in FIGS. 2 and 3, the polishing pad 35 is composed of a disk-shaped pad material such as a non-woven fabric or urethane containing abrasive grains. Also, as shown in FIGS. 2 and 3, a circular hole-shaped opening 35a is formed at the center of the polishing pad 35, and the lower surface of the polishing pad 35 constitutes a ring-shaped polishing surface.

[0026] Here, as shown in FIGS. 2 and 3, the polishing pad 35 has an area that covers the wafer W held on the holding surface of the chuck table 10 from above. Specifically, as shown in FIG. 5, the outer diameter φD of the polishing pad 35 is set larger than the outer diameter φd of the wafer W (φD > φd), and the polishing pad 35 is rotationally driven about the rotation axis CL2 of the spindle 33. As shown in FIG. 1, in the polishing mechanism 30, three load sensors 36 for detecting the reaction force received by the polishing pad 35 from the wafer W during the polishing process of the wafer W are arranged at equal angular pitches (120° pitch) in the circumferential direction, and these load sensors 36 are electrically connected to the control unit 60.

[0027] (Lifting mechanism) As shown in FIG. 1, on the -X-axis direction end portion (rear end portion) of the upper surface of the base 70, a rectangular box-shaped column 72 is vertically erected, and a lifting mechanism 40 is provided on the +Y-axis direction end surface (front surface) of this column 72. This lifting mechanism 40 moves the polishing mechanism 30 up and down along the direction (Z-axis direction) perpendicular to the holding surface of the chuck table 10, and moves a rectangular plate-shaped lifting plate 41 attached to the back surface of the holder 31 up and down in the Z-axis direction (vertical direction) along a pair of left and right guide rails 42 together with the holder 31, the spindle motor 32, the spindle 33, the polishing pad 35, etc. held by the holder 31. Here, the pair of left and right guide rails 42 are arranged perpendicular and parallel to each other on the front surface of the column 72.

[0028] Then, as shown in FIG. 1, between the pair of left and right guide rails 42, a rotatable ball screw 43 is vertically erected along the Z-axis direction (vertical direction), and the upper end of the ball screw 43 is connected to a servo motor 44 that can rotate forward and backward, which is a drive source. Also, the lower end of the ball screw 43 is rotatably supported by the column 72 by a bearing (not shown), and a nut member (not shown) that protrudes horizontally rearward from the back surface of the lifting plate 41 is screwed onto this ball screw 43.

[0029] (Air supply means) The air supply means 50 supplies compressed air from the central portion of the polishing pad 35 toward the wafer W during the polishing process of the wafer W. As shown in FIG. 3, it includes an air supply path 51 vertically penetrating through the spindle motor 32, the spindle 33, the mount 34, and the axis center of the polishing pad 35 of the polishing mechanism 30, and an air supply source 52 such as an air compressor connected to the other end (upper end) of the air supply path 51. Here, one end (lower end) of the air supply path 51 opens to a circular hole-shaped opening 35a formed in the central portion of the polishing pad 35.

[0030] Also, the other end (upper end) of the air supply path 51 is connected to the air supply source 52 through a vertical communication path 53a formed in the axis center of a rotary joint 53 connected to the upper end of the spindle motor 32 and an air pipe 55 having one end connected to an air plug 54 attached to the upper end of the rotary joint 53. An electromagnetic (solenoid type) on-off valve V for opening and closing the air supply path 51 is provided in the air pipe 55. The on-off valve V is electrically connected to the control unit 60, and as will be described later, its opening and closing operation is controlled by the control unit 60.

[0031] By the way, as shown in FIG. 3, the rotary joint 53 is composed of a rotor 53A that rotates together with the spindle motor 32 and a fixed-side stator 53B arranged around the rotor 53A. A minute annular gap is formed between these rotor 53A and stator 53B. Here, an annular path 53b is formed inside the stator 53B, and a plurality of air nozzles 53c extend radially from the annular path 53b. These air nozzles 53c open to the annular gap between the rotor 53A and the stator 53B. And a communication path 53d extending horizontally outward in the radial direction is formed in the stator 53B, and an air plug 57 is attached to this communication path 53d.

[0032] Also, a branch pipe 56 branches off from the air pipe 55, and this branch pipe 56 is connected to the air plug 57. Therefore, the compressed air supplied from the air supply source 52 is introduced into the annular path 53b through the air pipe 55, the branch pipe 56, and the communication path 53d, and is jetted from a plurality of air nozzles 53c extending from the annular path 53b into the annular gap between the rotor 53A and the stator 53B, and the annular gap is sealed with air (air seal). Note that the air jetted into the annular gap is discharged into the atmosphere from the exhaust port 31a opening at the upper part of the holder 31.

[0033] (Control Unit) The control unit 60 controls each component constituting the polishing apparatus 1, and includes a CPU (Central Processing Unit) that performs arithmetic processing according to a control program, and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). In particular, in the present embodiment, as will be described later, when polishing the wafer W, the opening and closing valve V is opened, and compressed air is jetted from the air supply source 52 through the air supply path 51 toward the wafer W from the opening 35a of the polishing pad 35, thereby performing the function of removing polishing debris from the polished surface (upper surface) of the wafer W.

[0034] [Operation of the Polishing Apparatus] Next, the operation of the polishing apparatus 1 configured as described above, that is, the wafer polishing method performed using the polishing apparatus 1 will be described below with reference to FIGS. 2 to 8.

[0035] As shown in FIG. 3, the method of polishing the wafer W in the polishing apparatus 1 shown in FIG. 1 is to align the center of the wafer W held on the holding surface of the chuck table 10 with the center of the polishing pad 35 in the Y-axis direction, and as shown in FIG. 4, with the center of the wafer W and the center of the polishing pad 35 offset by the illustrated distance ε in the X-axis direction, the upper surface of the wafer W is dry polished by the polishing pad 35. Here, the wafer W is sucked and held on the conical holding surface of the porous member 11 of the chuck table 10. This thin disk-shaped wafer W is deformed into a conical shape along the shape of the holding surface of the chuck table 10 and adheres closely to the holding surface.

[0036] In the polishing process of the wafer W held on the holding surface of the chuck table 10, as shown in FIG. 2, the semi-circular region (contact region shown in FIG. 7) W1 of the wafer W is parallel to the horizontal polishing surface (lower surface) of the polishing pad 35 that rotates around the vertical rotation axis CL2. The chuck table 10 is tilted by the illustrated angle α with respect to the horizontal plane by an inclination adjustment mechanism constituted by an actuator 14 or the like. That is, the rotation axis CL1 of the chuck table 10 is tilted by the angle α with respect to the vertical rotation axis CL2 of the spindle 33. In this way, when the chuck table 10 is tilted by a predetermined angle α with respect to the horizontal plane, as shown in FIGS. 3 and 5, the polishing surface of the polishing pad 35 contacts a part (contact region hatched in FIG. 7) W1 of the wafer W and polishes the contact portion W1. However, as described later, the chuck table 10 and the wafer W rotate at a predetermined speed by the rotation mechanism 2 shown in FIG. 1, so the entire upper surface of the wafer W is polished by the polishing pad 35. In the present embodiment, the chuck table 10 is tilted by a predetermined angle α with respect to the horizontal plane, but the polishing pad 35 may be tilted by a predetermined angle α with respect to the horizontal plane. Also, in FIG. 2, the inclination angle of the conical holding surface of the chuck table 10 (porous member 11) is exaggeratedly illustrated, but actually, this inclination angle is a minute angle that cannot be confirmed by the naked eye.

[0037] Here, the procedure of the polishing method for the wafer W will be described according to the flowchart shown in FIG. 8.

[0038] When polishing the wafer W, the wafer W is sucked and held on the holding surface of the chuck table 10 (step S1 in FIG. 8). That is, when the porous member 11 of the chuck table 10 is connected to a suction source (not shown), the porous member 11 is evacuated and a negative pressure is generated in the porous member 11. Then, the wafer W is sucked and held on the holding surface of the chuck table 10 as shown in FIG. 2 by this negative pressure.

[0039] As described above, when the wafer W is sucked and held on the holding surface of the chuck table 10, the chuck table 10 and the wafer W held thereon are moved under the polishing pad 35 by the horizontal movement mechanism 20 shown in FIG. 1 (step S2 in FIG. 8).

[0040] Thereafter, the chuck table 10 and the wafer W held thereon are rotationally driven at a predetermined speed in the direction of the arrow in FIG. 2 by the rotation mechanism 2 shown in FIG. 1, and the polishing pad 35 is rotationally driven in the direction of the arrow in FIG. 2 by the spindle motor 32 (see FIG. 1) (step S3 in FIG. 8). In the rotation mechanism 2 shown in FIG. 1, when the drive motor 4 is started and the drive pulley 5 is rotationally driven at a predetermined speed, the rotation of the drive pulley 5 is transmitted to the driven pulley 6 via the timing belt 7. Therefore, the driven pulley 6 and the table rotation shaft 12 rotate. Accordingly, the chuck table 10 attached to the table rotation shaft 12 and the wafer W held thereon are rotationally driven at a predetermined speed. At this time, the rotation speed of the drive motor 4 and the like are detected by the encoder 8, and the detection signal is transmitted to the control unit 60.

[0041] Next, from the state shown in FIG. 2, the polishing pad 35 descends by the elevating mechanism 40 shown in FIG. 1 and approaches the wafer W (step S4 in FIG. 8). At this time, it is determined by the three load sensors 36 shown in FIG. 1 whether or not the polishing surface (lower surface) of the polishing pad 35 has come into contact with the upper surface of the wafer W (step S5 in FIG. 8). When the polishing surface (lower surface) of the polishing pad 35 comes into contact with the upper surface of the wafer W, the reaction force received by the load sensor 36 increases rapidly. Therefore, the control unit 60 determines that the polishing pad 35 has come into contact with the wafer W based on this rapid increase in the reaction force.

[0042] When the polishing pad 35 comes into contact with the wafer W (step S5: Yes), the control unit 60 opens the on-off valve V of the air supply means 50 (step S6 in FIG. 8). Then, as shown by the arrows in FIGS. 3 and 4, compressed air flows from the air supply source 52 of the air supply means 50 downward through the air pipe 55, the communication path 53a, and the air supply path 51, and the air is jetted from the opening 35a formed in the central portion of the polishing pad 35 toward the upper surface of the central portion of the wafer W. At the same time, the entire upper surface of the wafer W is polished by the polishing pad 35 (step S7 in FIG. 8), and the grinding marks formed on the upper surface of the wafer W by the grinding process in the previous grinding process are removed, thereby increasing the flexural strength of the wafer W. When the polishing pad 35 does not come into contact with the wafer W (step S5: No), the descent of the polishing pad 35 is continued until the polishing pad 35 comes into contact with the wafer W (step S4 → step S5).

[0043] Thus, in the present embodiment, as shown in FIGS. 3 and 4, since the chuck table 10 is tilted by the illustrated angle α, a minute gap δ shown in detail in FIGS. 5 and 6 is formed between the non-contact region W2 (see FIG. 7) where the polishing pad 35 does not contact during polishing and the lower surface of the polishing pad 35, and the width of this gap δ gradually increases toward the outer side in the radial direction of the wafer W. Therefore, when compressed air is jetted from the opening 35a formed in the central portion of the polishing pad 35 toward the upper surface of the wafer W, the polishing debris generated by polishing the wafer W flows through the gap δ outward in the radial direction by the compressed air and is discharged from the gap δ as shown in FIGS. 5 and 6. In this case, since the wafer W is rotating, the polishing debris is discharged out of the gap δ from the entire upper surface of the wafer W and is surely removed, and the polishing debris does not remain at the central portion of the upper surface of the wafer W as in the prior art. For this reason, the cleaning of the wafer W performed after the polishing process can be carried out in a short time, and as a result, the productivity is enhanced.

[0044] Then, as described above, when polishing the wafer W while jetting compressed air from the opening 35a formed in the central portion of the polishing pad 35 toward the upper surface of the wafer W, the thickness of the wafer W is measured by a thickness measuring device (not shown) (step S8 in FIG. 8). Then, the control unit 60 determines whether or not the thickness of the wafer W has reached a predetermined value (step S9 in FIG. 8). When the thickness of the wafer W reaches the predetermined value (step S9: Yes), the elevating mechanism 40 shown in FIG. 1 is activated to raise the polishing pad 35 in the +Z axis direction (step S10 in FIG. 8). When the thickness of the wafer W does not reach the predetermined value (step S9: No), the polishing process of the wafer W is continued until the thickness of the wafer W reaches the predetermined value (steps S7 to S9).

[0045] Then, as described above, when the polishing pad 35 is lifted by the lifting mechanism 40 after the polishing process, the control unit 60 determines whether the polishing pad 35 has separated from the upper surface of the wafer W (step S11 in FIG. 8). If it is determined that the polishing pad 35 has separated from the wafer W (step S11: Yes), the control unit closes the on-off valve V of the air supply means 50 to cut off the supply of compressed air from the air supply source 52 to the opening 35a of the polishing pad 35 (step S12 in FIG. 8), and ends a series of polishing of the wafer W (step S13 in FIG. 8). When the polishing pad 35 separates from the wafer W, the reaction force from the wafer W detected by the three load sensors 36 shown in FIG. 1 rapidly decreases. Therefore, it is detected that the polishing pad 35 has separated from the wafer W due to this rapid decrease in the reaction force. And when it is determined that the polishing pad 35 has not separated from the wafer W (step S11: No), the lifting of the polishing pad 35 continues (step S11).

[0046] [Configuration of Grinding and Polishing Apparatus] Next, the configuration of a grinding and polishing apparatus as another form of the processing apparatus according to the present invention will be described with reference to FIGS. 9 and 10. In the following description, the directions of the arrows shown in FIG. 9 are defined as the X-axis direction (front-rear direction), Y-axis direction (left-right direction), and Z-axis direction (up-down direction), respectively.

[0047] The grinding and polishing apparatus 101 shown in FIG. 1 is an apparatus that grinds (rough grinding and finish grinding) and polishes the upper surface of the wafer W shown in FIG. 10, and then cleans the polished wafer W. This grinding and polishing apparatus 101 mainly includes four chuck tables 110 that hold the wafer W shown in FIG. 10, a first transfer mechanism 112 and a second transfer mechanism 113 that take in and out the wafer W with respect to the chuck table 110, a rough grinding mechanism 120 that grinds the wafer W held by the chuck table 110, a finish grinding mechanism 130, and a polishing mechanism 140.

[0048] Note that, as other components, the grinding and polishing apparatus 101 includes a cleaning mechanism 150 for cleaning the upper surface of the wafer W, a cassette 114 for storing a plurality of wafers W before processing, a cassette 115 for storing the processed wafers W, an alignment table 116 for aligning the wafers W taken out from the cassette 114, and a transfer robot 117 for taking in and out the wafers W with respect to the cassettes 114 and 115 and transferring the wafers W taken out from the cassette 114 to the alignment table 116. However, detailed descriptions thereof are omitted.

[0049] Here, the configurations of the chuck table 110, the first transfer mechanism 112, the second transfer mechanism 113, the rough grinding mechanism 120, the finish grinding mechanism 130, and the polishing mechanism 140, which are the main components of the grinding and polishing apparatus 101, will be described respectively.

[0050] (Chuck Table) In the present embodiment, four chuck tables 110 are arranged on a disk-shaped turntable 102 at equal angular pitches (90° pitches) in the circumferential direction. Here, the turntable 102 is intermittently rotatable by 90° around a central axis perpendicular to the Z-axis direction. Each of the four chuck tables 110 arranged on the turntable 102 can rotate (spin) around a central axis perpendicular to the Z-axis direction by a rotation mechanism (not shown), and can revolve intermittently by 90° together with the turntable 102 to sequentially move between the wafer transfer-in / out region R1, the rough grinding region R2, the finish grinding region R3, and the polishing region R4.

[0051] (First and Second Transfer Mechanisms) The first transfer mechanism 112 is taken out from the cassette 114 by the transfer-in / out robot 117 and transferred to the alignment table 116, and has the function of holding the wafer W aligned on the alignment table 116 and delivering it to the chuck table 110 located in the wafer transfer-in / out region R1. Also, the second transfer mechanism 113 has the function of taking out the wafer W whose upper surface has been polished by the polishing mechanism 140 from the chuck table 110 located in the polishing region R4 and delivering it to the cleaning mechanism 150. Note that the configurations of these first transfer mechanism 112 and second transfer mechanism 113 are the same.

[0052] (Rough grinding mechanism, finish grinding mechanism and polishing mechanism) As shown in FIG. 11, the rough grinding mechanism 120 is vertically arranged at the -X-axis direction end portion (rear end portion) on the base 200 in the shape of a rectangular box that is long in the Y-axis direction (left-right direction), and the finish grinding mechanism 130 and the polishing mechanism 140 are vertically arranged in a state of being juxtaposed along the X-axis direction (front-rear direction) at the +Y-axis direction end portion (right end portion) on the base 200.

[0053] The rough grinding mechanism 120 is a mechanism for rough grinding the upper surface of the wafer W held on the holding surface of the chuck table 110 located in the rough grinding region R2, and the finish grinding mechanism 130 is a mechanism for finish grinding the upper surface of the wafer W held on the holding surface of the chuck table 110 located in the finish grinding region R3, and the basic configurations of both are the same.

[0054] That is, the rough grinding mechanism 120 includes a spindle motor 122 fixed to the holder 121, a vertical spindle 123 rotationally driven by the spindle motor 122, a disk-shaped mount 124 attached to the lower end of the spindle 123, and a grinding wheel 125 detachably mounted on the lower surface of the mount 124. Here, the grinding wheel 125 is provided with a plurality of block-shaped grinding wheels 125a arranged in an annular shape.

[0055] Further, similar to the rough grinding mechanism 120, the finish grinding mechanism 130 also includes a spindle motor 132 fixed to a holder 131, a vertical spindle 133 rotationally driven by the spindle motor 132, a disk-shaped mount 134 attached to the lower end of the spindle 133, and a grinding wheel 135 detachably attached to the lower surface of the mount 134. Here, the grinding wheel 135 is provided with a plurality of block-shaped grinding wheels 135a arranged in an annular shape, and these grinding wheels 135a are composed of finer abrasive grains than the grinding wheels 125a of the rough grinding mechanism 120.

[0056] Incidentally, the rough grinding mechanism 120 and the finish grinding mechanism 130 are supported so as to be movable up and down by a lifting mechanism 103 provided on each column 201 in a block shape vertically erected on the base 200. Here, each lifting mechanism 103 moves the rough grinding mechanism 120 and the finish grinding mechanism 130 independently up and down along the Z-axis direction (vertical direction), and includes a lifting plate 104 in a rectangular plate shape and a pair of guide rails 105 for guiding the lifting movement of the lifting plate 104. Here, the rough grinding mechanism 120 and the finish grinding mechanism 130 are respectively attached to each lifting plate 104. Further, the pair of guide rails 105 are arranged perpendicular to the column 201 and parallel to each other.

[0057] And between the pair of guide rails 105 of each lifting mechanism 103, a rotatable ball screw 106 is vertically erected along the Z-axis direction (vertical direction), and the upper end of the ball screw 106 is connected to a servo motor 107 that can rotate forward and backward and is a drive source. Further, the lower end of the ball screw 106 is rotatably supported by the column 201 by a bearing (not shown), and a nut member (not shown) horizontally protruding from the back surface of the lifting plate 104 is screwed onto the ball screw 106.

[0058] Therefore, when the servo motors 107 of each lifting mechanism 103 configured as described above are activated to rotate the respective ball screws 106 forward and backward, each lifting plate 104 having a nut member (not shown) screwed onto each ball screw 106 moves up and down along the guide rail 105. As a result, the rough grinding mechanism 120 and the finish grinding mechanism 130 attached to the lifting plate 104 also move up and down independently of each other along the Z-axis direction (vertical direction).

[0059] Further, the polishing mechanism 140 is a mechanism for polishing the upper surface of the wafer W finish-ground by the finish grinding mechanism 130, and includes a spindle motor 142 fixed to a holder 141, a vertical spindle 143 rotationally driven by the spindle motor 142, a disk-shaped mount 144 attached to the lower end of the spindle 143, and a disk-shaped polishing pad 145 detachably attached to the lower surface of the mount 144.

[0060] The polishing mechanism 140 is movable up and down along the direction (Z-axis direction) perpendicular to the holding surface of the chuck table 110 by the same lifting mechanism 103 provided in the rough grinding mechanism 120 and the finish grinding mechanism 130, and is horizontally movable along the X-axis direction by an X-axis moving mechanism 160. The X-axis moving mechanism 160 includes a pair of upper and lower guide rails 161 arranged in parallel along the X-axis direction on a column 202 vertically erected on a base 200, a rectangular plate-shaped slider 162 horizontally movable along the guide rails 161, a servo motor 163 installed on the slider 162, and a ball screw (not shown) that can be rotated forward and backward by the servo motor 163. This ball screw is screwed and inserted into a nut member (not shown) protruding from the back surface of the slider 162. A pair of guide rails 1055 of the lifting mechanism 103 are attached to the slider 162.

[0061] Therefore, when the servo motor 163 is activated to rotate the ball screw (not shown) forward and backward, the slider 162 having a nut member (not shown) screwed onto the ball screw can move horizontally along the pair of upper and lower guide rails 161 in the Y-axis direction.

[0062] [Function of Grinding and Polishing Device] Next, the grinding (rough grinding and finish grinding) and polishing of the wafer W by the grinding and polishing device 101 configured as described above will be described. (Grinding)

[0063] First, when grinding the wafer W, one wafer W before processing is taken out from the cassette 114 by the loading / unloading robot 117 shown in FIG. 9, and the taken-out wafer W is transferred to the alignment table 116. Then, on the alignment table 116, the wafer W is aligned, and the aligned wafer W is sucked and held by the first transfer mechanism 112 and transferred to the chuck table 110 located in the wafer loading / unloading region R1, and is held on the chuck table 110.

[0064] As described above, when the wafer W is held on the chuck table 110, the turntable 102 rotates by an angle of 90° in the direction of the arrow in FIG. 9 (clockwise) around its vertical axis center, and the chuck table 110 moves to the rough grinding region R2 together with the wafer W. In this rough grinding region R2, the upper surface of the wafer W held on the holding surface of the chuck table 110 is rough ground by the rough grinding mechanism 120.

[0065] Here, as shown in FIG. 10, a porous disk-shaped porous member 111 is incorporated above the chuck table 110, and the upper surface of this porous member 111 constitutes a conical holding surface with the center as the apex. The chuck table 110 is tilted by an angle β shown in the figure with respect to the horizontal plane by a tilt adjustment mechanism (not shown), and the radius region of the conical holding surface is parallel to the grinding surface (lower surface) of the grinding wheel 125a. When the thin disk-shaped wafer W is sucked and held by the conical holding surface of the chuck table 110, the wafer W is deformed into a conical shape along the shape of the holding surface and adheres closely to the holding surface. The chuck table 110 and the wafer W held thereon are rotationally driven at a predetermined speed in the direction of the arrow in FIG. 10 by a rotation mechanism (not shown), and the grinding wheel 125a is rotationally driven at a predetermined speed in the direction of the arrow in FIG. 10 by the spindle motor 122.

[0066] As described above, in a state where the wafer W held on the chuck table 110 and the grinding wheel 125a of the grinding wheel 125 are rotationally driven at a predetermined speed in the direction of the arrow in FIG. 10, when the grinding wheel 125a descends in the -Z axis direction by the lifting mechanism 103, the grinding wheel 125a contacts the upper surface of the wafer W and roughly grinds the entire upper surface of the wafer W.

[0067] Then, when the upper surface of the wafer W is roughly ground to a predetermined thickness by the rough grinding mechanism 120, the rough grinding mechanism 120 rises in the +Z axis direction by the lifting mechanism 103 and the grinding wheel 125a separates from the upper surface of the wafer W. Then, the turntable 102 rotates by an angle of 90° around its vertical axis center, and the wafer W rough ground in the rough grinding region R2 and the chuck table 110 holding the same move to the finish grinding region R3, and the upper surface of the wafer W is finish ground by the finish grinding mechanism 130 in this finish grinding region R3. Note that the finish grinding of the wafer W by the finish grinding mechanism 130 is the same as the rough grinding of the wafer W by the rough grinding mechanism 120, so the description of this finish grinding is omitted.

[0068] (Polishing process) As described above, when the upper surface of the wafer W is finish-ground by the finish-grinding mechanism 130, the turntable 102 rotates by an angle of 90° around its vertical axis center, and the wafer W whose upper surface has been finish-ground in the finish-grinding area R3 and the chuck table 110 holding the same move to the polishing area R4, and the upper surface of the wafer W is polished by the polishing mechanism 140 in this polishing area R4. Note that the polishing process of the wafer W by this polishing mechanism 140 is the same as the polishing process in the polishing apparatus 1 shown in FIG. 1, and since the same effect as described above can be obtained, a description of this polishing process will not be repeated.

[0069] Subsequently, in the polishing mechanism 140, when the upper surface of the wafer W is polished by the polishing pad 145, the polishing pad 145 is lifted by the elevating mechanism 103 and separated from the upper surface of the wafer W. Then, the wafer W for which polishing has been completed is held by the second transfer mechanism 113 and removed from the chuck table 110, and the removed wafer W is transferred to the cleaning mechanism 150. In the cleaning mechanism 150, the wafer W is fixed on the spinner table 151, and the wafer W is rotationally driven at a predetermined speed around a vertical central axis together with the spinner table 151, and cleaning water (for example, pure water) is sprayed onto the upper surface of the wafer W from the cleaning nozzle 152, whereby the upper surface of the wafer W is cleaned. Then, the cleaned wafer W is removed from the spinner table 151 by the transfer-in / out robot 117 and stored in the cassette 115, and a series of processes (rough grinding, finish grinding, and polishing) for the wafer W are completed.

[0070] Also, in the grinding and polishing apparatus 101 according to the present embodiment, when the wafer W is polished by the polishing mechanism 140, as in the polishing apparatus 1 shown in FIG. 1, compressed air is jetted from an air supply source (not shown) toward the upper surface of the wafer W. Therefore, the abrasive debris formed in the minute gap between the polishing pad 145 and the wafer W held on the conical holding surface is discharged outside the wafer W along the air flow flowing from the center of the wafer W toward the radially outer side, and the polishing process is performed while removing the abrasive debris from the upper surface of the wafer W. Further, compressed air is jetted until the polishing process is completed and the wafer W is completely separated from the polishing pad. For this reason, no abrasive debris remains on the upper surface of the wafer W, the cleaning of the wafer W in the cleaning mechanism 150 can be performed in a short time, and as a result, the effect of enhancing the productivity can be obtained.

[0071] Note that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible within the scope of the technical idea described in the claims, the specification, and the drawings.

Explanation of Reference Numerals

[0072] 1: Polishing apparatus (processing apparatus), 2: Rotation mechanism, 3: Bracket, 4: Driving motor, 5: Driving pulley, 6: Driven pulley, 7: Timing belt, 8: Encoder, 10: Chuck table, 10A: Frame body, 11: Porous member, 12: Table rotation shaft, 13: Flange, 14: Actuator, 15: Cover, 16, 17: Telescopic cover, 20: Horizontal movement mechanism, 21: Slider, 22: Guide rail, 23: Ball screw, 24: Servo motor, 25: Bearing, 30: Polishing mechanism, 31: Holder, 31a: Exhaust port, 32: Spindle motor, 33: Spindle, 34: Mount, 35: Polishing pad, 35a: Opening, 36: Load sensor, 40: Lifting mechanism, 41: Lifting plate, 42: Guide rail, 43: Ball screw, 44: Servo motor, 50: Air supply means, 51: Air supply path, 52: Air supply source, 53: Rotary joint, 53A: Rotor, 53B: Stator, 53a: Communication path, 53b: Annular path, 53c: Air nozzle, 53d: Communication path, 54: Air plug, 55: Air pipe, 56: Branch pipe, 57: Air plug, 60: Control unit, 70: Base, 70a: Opening, 71: Inner base, 72: Column, 101: Grinding and polishing device (processing device), 102: Turntable, 103: Lifting mechanism, 104: Lifting plate, 105: Guide rail, 106: Ball screw, 107: Servo motor, 110: Chuck table, 111: Porous member, 112: First conveying mechanism, 113: Second conveying mechanism, 114, 115: Cassette, 116: Alignment table, 117: Loading / unloading robot, 120: Rough grinding mechanism, 121: Holder, 122: Spindle motor, 123: Spindle, 124: Mount, 125: Grinding wheel, 125a: Grinding stone, 130: Finish grinding mechanism, 131: Holder, 132: Spindle motor, 133: Spindle, 134: Mount, 135: Grinding wheel, 135a: Grinding stone, 140: Polishing mechanism, 141: Holder, 142: Spindle motor, 143: Spindle, 144: Mount, 145: Polishing pad, 150: Cleaning mechanism, 151: Spinner table, 152: Cleaning nozzle, 160: X-axis moving mechanism, 161: Guide rail, 162: Slider, 163: Servo motor, 200: Base, 201, 201: Column, CL1: Rotation axis center of chuck table, CL2: Rotation axis center of spindle, φD: Outer diameter of polishing pad, φd: Outer diameter of wafer, V: On-off valve, W: Wafer, W1: Contact area of wafer, W2: Non-contact area of wafer, α, β: Tilt angles of the chuck table, ε: Offset amount between the wafer center and the polishing pad center, δ: Gap

Claims

1. A processing apparatus comprising: a chuck table for holding a wafer by a conical holding surface; a polishing mechanism for polishing the wafer held on the chuck table with a polishing pad mounted on a spindle; and a control unit, wherein the polishing pad has an opening at a central portion and includes an annular polishing surface, the chuck table and the polishing pad are relatively inclined such that a contact area of the holding surface is parallel to the polishing surface of the polishing pad, the polishing mechanism includes an air supply passage having one end opening into the opening of the polishing pad and the other end connected to an air supply source, and an opening / closing valve for opening and closing the air supply passage, the control unit is characterized in that the opening / closing valve is opened when the polishing surface of the polishing pad contacts a contact area of the wafer held on the chuck table to polish the wafer.

2. The processing apparatus according to claim 1, further comprising a grinding mechanism for grinding the entire surface of the wafer by bringing an annular grinding wheel into contact with a part of the wafer held on the chuck table, wherein the polishing mechanism polishes a ground surface of the wafer ground by the grinding mechanism.

Images