JP4488799B2 - Wafer cleaning apparatus and wafer cleaning method - Google Patents

Description

  The present invention relates to a wafer cleaning apparatus for cleaning an outer peripheral region of a wafer.

  A semiconductor wafer on which an integrated circuit is formed is divided into individual devices by dicing or the like, and such a semiconductor wafer is manufactured by forming an insulating film or a wiring layer on the surface of a silicon wafer or the like. Is done. In the process, various substances such as silane, aluminum, copper, phosphorus, manganese, platinum are laminated in a complicated manner. Therefore, in the process of laminating each of these substances, only the desired substance is laminated. It is necessary to maintain an environment that does not contain other substances.

  However, in each stacking process, the area where the device in the center of the wafer is formed is masked to prevent impurities from entering, but the wafer outer peripheral area is not specially processed. There is a problem that substances adhered in each lamination process remain in the wafer outer peripheral region, and the adhered substances contaminate the environment in the subsequent process.

  Therefore, before moving to the step of laminating the next substance, a substance causing contamination is removed from the wafer outer peripheral region and cleaned (see, for example, Patent Document 1).

JP 2002-110593 A

  However, when removing the substance adhering to the wafer outer peripheral area, means for removing the substance may be applied to the area where the device is formed beyond the wafer outer peripheral area. Will be reduced. Therefore, the problem to be solved by the present invention is to remove only the substances adhering to the outer peripheral region of the wafer and not to adversely affect the region where the device is formed.

The present invention is a wafer cleaning apparatus for cleaning an outer peripheral region of a wafer, a chuck table that can hold and rotate a wafer, and a polishing means for polishing an outer peripheral region of the wafer held on the chuck table, Polishing means for mirror-finishing the outer peripheral area held by the chuck table and polished by the polishing means, and imaging the wafer held by the chuck table to recognize the device formation area and detect the outer peripheral area to be cleaned And an alignment unit, and the polishing unit is formed in a cylindrical shape and acts on the outer peripheral region of the wafer to perform polishing, and a notch formed in the outer peripheral region that protrudes from the outer peripheral polishing unit to the outer peripheral side. It is composed of a grinding wheel composed of a notch grinding part to be ground, and a grinding wheel driving part for rotating the grinding wheel, The polishing means includes a polishing pad formed of an outer periphery polishing portion that is formed in a columnar shape and performs polishing on the outer peripheral region, a notch polishing portion that protrudes from the outer periphery polishing portion to the outer periphery side and polishes a notch, and a polishing It is comprised from the pad drive part which rotates a pad, It is characterized by the above-mentioned.

  The present invention also provides a method for cleaning an outer peripheral region of a wafer composed of a device forming region and an outer peripheral region using the wafer cleaning apparatus, wherein the device forming region is detected by an alignment means, and the device forming region On the basis of the positional information, the polishing means or the polishing means is made to act only on the outer peripheral area.

  When a notch is formed in the outer peripheral region of the wafer, the notch can be detected by the alignment means, and the notch polishing part or the notch polishing part can be applied to the notch based on the position information of the notch.

  In the wafer cleaning apparatus according to the present invention, the wafer cleaning apparatus according to the present invention includes an alignment unit that captures an image of the wafer held on the chuck table, recognizes a device formation region, and detects an outer peripheral region to be cleaned. Since the means can be operated, the material adhered to the outer peripheral region can be efficiently removed and mirror-finished without damaging the device region, and deterioration of the quality of the device constituting the wafer can be prevented.

  Further, the polishing means rotates the polishing grindstone including an outer peripheral polishing portion that acts on the outer peripheral region of the wafer and polishes, and a notch polishing portion that polishes the notch formed in the outer peripheral region of the wafer, and the polishing grindstone. A polishing pad comprising a grinding wheel drive unit, and a polishing means comprising an outer periphery polishing unit that acts on the outer peripheral region to perform polishing and a notch polishing unit that polishes the notch, and a pad drive unit that rotates the polishing pad; In the case of comprising, a wafer having a notch can be polished and polished on the outer peripheral region including the notch to remove the adhered substance and be mirror-finished.

  In the wafer cleaning method according to the present invention, the device forming region is detected by the alignment unit, and based on the position information of the device forming region, the polishing unit or the polishing unit can be applied only to the outer peripheral region. Can polish or polish only the outer peripheral region without the action of polishing means or polishing means.

  In addition, when a notch is formed in the outer peripheral area of the wafer, the notch is detected by the alignment means, and the notch is polished by applying the notch polishing portion or the notch polishing portion to the notch based on the position information of the notch. Or it can be polished.

  The wafer cleaning apparatus 1 in FIG. 1 has a configuration in which the holding means 3 can move in the Y-axis direction on the base 2 and the processing means 4 can move in the X-axis direction on the base 2. In addition, an alignment unit 5 having a function of recognizing a region where a device is formed by imaging a wafer to be processed is provided.

  The holding unit 3 includes a chuck table 30 that sucks and holds the wafer 10 and a table driving unit 31 that rotates the chuck table 30.

  The processing unit 4 includes a base 40 that can move in the X-axis direction, a lifting unit 41 that can be lifted and lowered relative to the base 40, a polishing unit 42 and a polishing unit 43 that are supported by the lifting unit 41.

The polishing means 42 polishes the outer peripheral region 101 of the wafer 10 held on the chuck table 30, and is rotated by being driven by the grindstone driving unit 420 disposed in the elevating unit 41 and the grindstone driving unit 420. The belt 421 includes a rotation shaft 422 around which the belt 421 is wound, and a polishing grindstone 423 fixed to the rotation shaft 422. The polishing grindstone 423 includes an outer peripheral polishing portion 423a formed in a columnar shape and a notch polishing portion 423b protruding from the outer peripheral polishing portion 423a to the outer peripheral side.

The polishing means 43 mirror-finishes the outer peripheral area 101 of the wafer 10 held on the chuck table 30 and polished on the outer peripheral area 101 by the polishing means 42. The polishing means 43 includes a pad driving part 430 disposed in the elevating part 41 and a pad. The belt 431 is driven and rotated by the driving unit 430, the rotating shaft 432 around which the belt 431 is wound, and the polishing pad 433 fixed to the rotating shaft 432. The polishing pad 433 includes an outer periphery polishing portion 433a formed in a columnar shape and a notch polishing portion 433b protruding from the outer periphery polishing portion 433a to the outer periphery side.

  The alignment unit 5 is movable at least in the Y-axis direction, and includes an imaging unit 50 that images the wafer 10 held on the chuck table 30 and a processing unit 51 that processes an image acquired by the imaging unit 50. . The processing unit 51 is connected to the control unit 6, and the control unit 6 can control the movement of the holding unit 3, the rotation of the chuck table 30, and the movement of the processing unit 4 based on information from the processing unit 51. it can. The control unit 6 can recognize the positions of the holding unit 3, the processing unit 4, and the alignment unit 5 by coordinates in a three-dimensional space using the X axis, the Y axis, and the Z axis.

  A polishing liquid supply means 7 and a CMP liquid supply means 8 are disposed in the vicinity of the processing means 4, and the polishing liquid is supplied from the polishing liquid supply means 7 to the processed portion of the wafer, and the CMP liquid supply is performed. The CMP liquid is supplied from the means 8 respectively.

  Next, a case where the outer peripheral area 101 of the wafer 10 shown in FIG. 1 is polished and polished will be described. At the center of the front surface 10 a of the wafer 10, there is a device forming region 102 composed of a plurality of devices 103, and the outer peripheral region 101 is formed on the outer peripheral side of the device forming region 102. A notch 104 that is a mark indicating a crystal orientation is formed in the outer peripheral region 101. The wafer 10 is held on the chuck table 30. Then, the alignment means 5 is positioned immediately above the wafer 10, and the surface 10a of the wafer 10 is imaged by the imaging unit 50, and the processing unit 51 obtains the X coordinate value X1 which is positional information of the outer edge of the wafer 10 shown in FIG. The calculated image is stored in the control unit 6, and the X coordinate value X 2 that is the position information of the outer edge of the device forming region 102, that is, the boundary between the device forming region 102 and the outer peripheral region 101, is stored in the control unit 6 Let

  With reference to FIG. 1, in the processing means 4, for example, the lower end of the peripheral polishing portion 423 a is slightly higher than the surface 10 a of the wafer 10 by raising and lowering the elevating unit 41 under the control of the control unit 6. To be positioned. The Z coordinate of the surface of the chuck table 30 is recognized in advance by the control unit 6, and a value obtained by adding the thickness of the wafer W to the value of the Z coordinate is stored in the control unit 6 as the Z coordinate of the surface 10a of the wafer 10. Has been.

  Next, the chuck table 30 is rotated at a slow rotational speed of, for example, about 0.5 rpm to 2.0 rpm, and the grinding wheel 423 is rotated at, for example, about 3000 rpm to 5000 rpm by the grindstone driving unit 420 to thereby change the processing means 4. By moving in the direction approaching the wafer 10 (+ X direction) and further lowering the polishing grindstone 423, as shown in FIG. 3, the outer peripheral polishing portion 423a of the polishing grindstone 423 that rotates to the outer peripheral region 101 of the surface 10a of the wafer 10 is obtained. Contact.

  Here, when the processing means 4 is moved in the + X direction, the lower end of the outer peripheral polishing portion 423a constituting the polishing grindstone 423 is positioned on the outer peripheral region 101, and the upper end of the device forming region 102 is moved. Do not let it. For this process, the X coordinate value X2 (see FIG. 2) of the outer edge of the device forming region 102 stored in the control unit 6 is used to prevent the lower end of the outer peripheral polishing unit 423a from moving to X2. Control in 6. In the coordinate system as shown in FIG. 2, the X coordinate X3 of the lower end of the outer peripheral polishing portion 423a is set to a value smaller than X2. By performing such control, it is possible to prevent the device formation region 102 from being polished and the quality of the device from being deteriorated.

  As described above, the processing means 4 is moved to the X-axis by the control unit 6 and the grinding wheel 423 is moved in the Z-axis direction by the lifting / lowering unit 41, so that the outer peripheral polishing unit 423a and the outer peripheral region 101 are moved as shown in FIG. Are in contact with each other, the processing means 4 is moved in the −X direction and the polishing grindstone 423 is moved in the −Z direction, so that the outer peripheral polishing portion 423 a Polishing is performed by acting on the front surface 10a and the side surface 10b of 101. After the polishing to the center of the side surface 10b, the processing means 4 is moved in the + X direction and the polishing grindstone 423 is moved in the -Z direction, so that the rotation center draws an arc and the side surface 10b and The back surface 10c is polished. When the outer peripheral polishing portion 423a is repeatedly reciprocated along such a trajectory, polishing is performed along the side surface of the outer peripheral region 101, and the adhered substance is removed by polishing.

  Next, the processing means 4 is moved in the direction away from the wafer 10 (−X direction) so that the outer peripheral polishing portion 423a is separated from the wafer 10, and the chuck table 30 is rotated slowly while the imaging portion of the alignment means 5 is moved. 50, images the side of the outer peripheral region 101 of the wafer 10 closest to the processing means 4 and sequentially acquires images in the processing unit 51. At the moment when the processing unit 51 detects the notch 104 from the acquired image, The control unit 6 controls the table driving unit 31 to stop the rotation of the chuck table 30 and positions the notch 104 at a position closest to the processing means 4. Further, by moving the holding means 3 in the Y-axis direction, as shown in FIG. 4, the notch 104 and the notch polishing portion 423b of the polishing grindstone 423 are positioned so as to be in a straight line in the X-axis direction. And the X coordinate X4 which is the positional information of the edge part 104a formed in the acute angle of the notch 104 at this time is memorize | stored in the control part 6. FIG.

  In the processing means 4, for example, the lower end of the notch polishing unit 423 b is positioned at a position slightly higher than the surface 10 a of the wafer 10 by moving the elevating unit 41 up and down. Then, by rotating the polishing grindstone 423 by, for example, about 3000 rpm to 5000 rpm by the grindstone driving unit 420, the processing means 4 moves in a direction approaching the wafer 10 and further lowers the polishing grindstone 423, as shown in FIG. The notch polishing part 423b of the rotating grinding wheel 423 is brought into contact with the outer peripheral region 101 of the surface 10a of the wafer 10. The method of controlling the processing means 4 here is the same as in the case of polishing by the outer peripheral polishing portion 423a.

  Then, by moving the processing means 4 in the X-axis direction by the control unit 6 and moving the polishing grindstone 423 in the Z-axis direction by the elevating unit 41, as shown in FIG. 6, the rotating notch polishing unit 423b and the notch 104 are rotated. When the notch polishing section 423b is repeatedly reciprocated in an arc shape while maintaining the contact state, the notch 104 is polished and the attached substance is removed.

  After the outer peripheral region 101 including the notch 104 has been polished as described above, the processing means 4 is moved in the −X direction and separated from the wafer 10, and then the elevating unit 41 is lowered to perform, for example, outer peripheral polishing. The lower end of the portion 433 a is positioned at a position slightly higher than the surface 10 a of the wafer 10.

  Then, the chuck table 30 is rotated at a slow rotational speed of, for example, about 0.5 rpm to 2.0 rpm, and the polishing pad 433 is rotated at, for example, about 3000 rpm to 5000 rpm by the pad driving unit 430, so that the processing means 4 As shown in FIG. 7, the outer peripheral polishing portion 433a of the rotating polishing pad 433 is brought into contact with the outer peripheral region 101 of the surface 10a of the wafer 10 by moving in a direction approaching 10 and further lowering the polishing pad 433.

  Here, when the processing means 4 is moved in the + X direction, the lower end of the outer peripheral polishing portion 433a is positioned on the outer peripheral region 101 and is not moved over the device forming region 102. For this purpose, the control unit 6 uses the X coordinate value X2 of the outer edge of the device formation region 102 stored in the control unit 6 to prevent the lower end X6 of the outer periphery polishing unit 433a from moving to X2, as shown in FIG. Control in 6. By performing such control, it is possible to prevent the device formation region 102 from being polished and the quality of the device from being deteriorated.

  Then, by moving the processing means 4 in the X-axis direction by the control unit 6 and moving the polishing pad 433 in the Z-axis direction by the elevating unit 41, as shown in FIG. 7, the outer polishing unit 433a, the outer peripheral region 101, and the like. The outer peripheral polishing portion 433a is moved along the front surface 10a, the side surface 10b, and the rear surface 10c of the outer peripheral region 101 while maintaining the contact state, and the front surface 10a, the side surface 10b, and the rear surface 10c are polished. For example, when the center of rotation of the outer periphery polishing portion 433a is repeatedly reciprocated so as to draw an arc, the outer periphery region 101 is mirror-finished.

Next, the processing means 4 is moved away from the wafer 10 to bring the outer peripheral polishing portion 433a away from the wafer 10, and the notch 104 is detected by the alignment means 5 while slowly rotating the chuck table 30. At the moment of detection, the control unit 6 controls the table driving unit 31 to stop the rotation of the chuck table 30 and fixes the notch 104 at a position closest to the processing means 4 as shown in FIG. Further, by moving the holding means 3 in the Y-axis direction, as shown in FIG. 9, the notch 104 and the notch polishing portion 433b of the polishing pad 433 are positioned so as to be in a straight line in the X-axis direction.

  On the other hand, in the processing means 4, for example, the lower end of the notch polishing portion 433 b is positioned at a position slightly higher than the surface 10 a of the wafer 10 by raising and lowering the elevating unit 41. Then, the polishing pad 433 is rotated by, for example, about 3000 rpm to 5000 rpm by the pad driving unit 430, the processing means 4 moves in a direction approaching the wafer 10, and the polishing pad 433 is further lowered, as shown in FIG. The notch polishing portion 433b of the rotating polishing pad 433 is brought into contact with the outer peripheral region 101 of the surface 10a of the wafer 10.

  Then, by moving the processing means 4 in the X-axis direction by the control unit 6 and moving the polishing pad 433 in the Z-axis direction by the elevating unit 41, as shown in FIG. 10, the rotating notch polishing unit 433b and the notch When the notch polishing portion 433b is repeatedly reciprocated in an arc shape while maintaining the state in contact with the 104, the notch 104 is polished and the notch 104 is mirror-finished.

  By adjusting the position of the wafer 10 in the vertical direction as described above, polishing and polishing can be performed only by changing the height, and the substance attached only to the outer peripheral region 101 of the wafer 10 including the notch 104 is removed. It can be removed efficiently and the outer peripheral area 101 can be mirror-finished. And since the substance laminated | stacked on the device formation area 102 is not accidentally removed, the quality of a device is not reduced. In addition, the wafer 10 on which the notch 104 is formed is polished and polished including the notch 104, so that the material adhering to the notch can be reliably removed and mirror finished.

  In the above example, the holding means 3 moves in the Y-axis direction and the polishing grindstone 423 and the polishing pad 433 move in the X-axis direction and the Z-axis direction. However, the present invention is limited to this configuration. The holding means 3, the polishing grindstone 423, and the polishing pad 433 may be relatively moved in the X-axis direction, the Y-axis direction, and the Z-axis direction. Further, the wafer to which the present invention is applied is not limited to a wafer in which a notch is formed.

It is a perspective view which shows an example of the wafer cleaning apparatus of this invention. It is explanatory drawing which shows X coordinate of a wafer and an outer periphery grinding | polishing part. It is a front view which shows a mode that the outer peripheral area | region of a wafer is grind | polished. It is explanatory drawing which shows the positional relationship of the notch of a wafer and a notch grinding | polishing part. It is a front view which shows a mode that the notch of a wafer is grind | polished. It is a top view which shows a mode that the notch of a wafer is grind | polished. It is a front view which shows a mode that the outer peripheral area | region of a wafer is polished. It is explanatory drawing which shows X coordinate of a wafer and an outer periphery polishing part. It is explanatory drawing which shows the positional relationship of the notch of a wafer and a notch polishing part. It is a front view which shows a mode that the notch of a wafer is grind | polished.

1: Wafer cleaning apparatus 2: Base 3: Holding means 30: Chuck table 31: Table driving unit 4: Processing means 40: Base 41: Lifting part 42: Polishing means
420: Grinding wheel drive unit 421: Belt 422: Rotating shaft
423: Polishing wheel
423a: peripheral polishing section 423b: notch polishing section 43: polishing means
430: Pad drive unit 431: Belt 432: Rotating shaft
433: Polishing pad
433a: Peripheral polishing part 433b: Notch polishing part 5: Alignment means 50: Imaging part 51: Processing part 6: Control part 7: Polishing liquid supply means 8: CMP liquid supply means 10: Wafer 10a: Front face 10b: Side face 10c: Back face 101: Peripheral area 102: Device formation area 103: Device 104: Notch

Claims (3)

A wafer cleaning apparatus for cleaning the outer peripheral area of a wafer,
A chuck table capable of sucking and holding a wafer and rotating,
Polishing means for polishing an outer peripheral region of the wafer held by the chuck table;
Polishing means for mirror-finishing the outer peripheral area held by the chuck table and polished by the polishing means;
And at least alignment means for recognizing a device formation region by imaging a wafer held on the chuck table and detecting an outer peripheral region to be cleaned,
The polishing means is formed in a cylindrical shape and acts on the outer peripheral region of the wafer to perform polishing, and a notch polishing that protrudes from the outer peripheral polishing portion to the outer peripheral side and polishes a notch formed in the outer peripheral region. And a grinding wheel composed of a grinding wheel and a grinding wheel drive unit that rotates the grinding wheel.
The polishing means is formed of a cylindrical outer peripheral polishing portion that acts on the outer peripheral region to perform polishing, and a notch polishing portion that protrudes from the outer peripheral polishing portion to the outer peripheral side and polishes the notch. A wafer cleaning apparatus comprising a pad and a pad driving unit for rotating the polishing pad . A method for cleaning the outer peripheral region of a wafer composed of a device forming region and an outer peripheral region using the wafer cleaning apparatus according to claim 1 ,
A wafer cleaning method in which the device forming region is detected by an alignment unit, and a polishing unit or a polishing unit is applied only to the outer peripheral region based on positional information of the device forming region. The peripheral region of the wafer is formed notch, the notch is detected by said alignment means, based on the position information of the notch, according to claim 2 which applies the notch polishing section or notch polishing section in the notch Wafer cleaning method.

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