JP7368137B2 - Wafer processing method - Google Patents

Description

The present invention relates to a wafer processing method.

There is a process using a grinding/polishing apparatus that grinds a wafer to a predetermined thickness using a grinding wheel, supplies slurry, and polishes the wafer by CMP using a polishing pad (see Patent Document 1).

In the grinding and polishing processing apparatus, a wafer held under suction on a holding surface of a chuck table is ground by a grinding wheel. Thereafter, the chuck table is positioned directly below the polishing pad, and the wafer is polished with the polishing pad while supplying slurry to the wafer.

JP2018-060871A Japanese Patent Application Publication No. 9-306881

Slurry usually contains fine free abrasive grains. Therefore, loose abrasive grains adhere to the outer peripheral edge of the wafer. Furthermore, as the polishing pad is rotated and pressed against the wafer, free abrasive particles enter between the bottom surface of the wafer and the holding surface of the chuck table, and the free abrasive particles are deposited on the bottom surface of the wafer (surface of the protective tape) and the holding surface. is attached. The loose abrasive grains attached to the holding surface deteriorate the thickness accuracy of the next wafer to be held.

Therefore, an object of the present invention is to suppress free abrasive grains from entering the gap between the lower surface of the wafer and the holding surface when grinding and polishing the wafer held on the chuck table.

The wafer processing method (this processing method) according to the present invention removes an oxide film formed on the ground surface of a wafer that has been ground to a predetermined thickness using a grinding wheel, using free abrasive grains, a polishing liquid, and fixed abrasive grains. A method for processing a wafer, in which the wafer is removed by polishing using a polishing pad, which includes a holding step in which the wafer is held by a chuck table, and the wafer held on the chuck table is ground to a predetermined thickness with a grinding wheel. In the grinding process, while rotating the polishing pad and rotating the chuck table holding the wafer at a faster rotation speed than the polishing pad, the free abrasive grains and the A first polishing step of supplying a polishing liquid, pressing the polishing pad against the surface to be ground of the wafer, and removing an oxide film on the surface to be ground of the wafer , and rotating the polishing pad and holding the wafer. The polishing liquid containing no free abrasive grains is supplied to the polishing surface of the wafer while rotating the chuck table at a faster rotation speed than the polishing pad, and the polishing solution is applied to the polishing surface of the wafer using the polishing pad. and a second polishing step of polishing the surface of the wafer to be polished while pressing and flowing the free abrasive grains from the surface of the wafer to be polished.

Further, in the first polishing step in the present processing method, a predetermined amount of the free abrasive grains may be added to the polishing liquid.

In this processing method, in the first polishing step, an oxide film formed on the upper surface of the wafer is removed using a polishing liquid containing free abrasive grains. Furthermore, in the second polishing step, a polishing liquid containing no free abrasive grains is used. In the second polishing process, since the oxide film is removed from the top surface of the wafer, the top surface of the wafer can be polished without using free abrasive grains due to the reaction between the wafer material (silicon, etc.) and the polishing liquid. is possible.

As a result, the free abrasive grains supplied to the top surface of the wafer in the first polishing step are washed away from the top surface of the wafer by the polishing liquid that does not contain free abrasive grains and is used in the second polishing step. Therefore, it is possible to prevent free abrasive grains from entering the gap between the lower surface of the wafer and the chuck table, and from adhering to the lower surface of the wafer and the chuck table.

Further, in the first polishing step, the amount of free abrasive grains added to the polishing liquid may be a predetermined amount. As a result, in the first polishing step, the amount of free abrasive grains may be too small and an oxide film remains on the top surface of the wafer, or the amount of free abrasive grains may be too large and the amount of free abrasive grains may be too large after the second polishing step. It is possible to prevent free abrasive grains from remaining.

FIG. 2 is a perspective view showing the configuration of a processing device. It is an explanatory view showing a holding process. It is an explanatory view showing a grinding process. It is an explanatory view showing a first polishing process. It is an explanatory view showing a second polishing process.

The processing apparatus 1 shown in FIG. Grind by. Furthermore, the processing apparatus 1 uses the polishing means 4 to polish the surface to be ground of the wafer W using free abrasive grains, a polishing liquid, and a polishing pad that does not contain fixed abrasive grains.

The wafer W shown in FIG. 1 is, for example, a circular semiconductor wafer. On the front surface Wa of the wafer W, devices (not shown) are formed. The front surface Wa of the wafer W faces downward in FIG. 1 and is protected by a protective tape T attached thereto. The back surface Wb of the wafer W becomes a processed surface to which a grinding process and a polishing process are performed.

The processing device 1 includes a first device base 10 and a second device base 11 disposed behind the first device base 10 (on the +Y direction side). Above the first device base 10 is a loading/unloading area A where wafers W are loaded/unloaded. A processing area B is formed on the second device base 11. In this processing area B, the wafer W held on the chuck table 5 is processed by the rough grinding means 30, the finishing grinding means 31, or the polishing means 4.

A first cassette stage 150 and a second cassette stage 151 are provided on the front side (-Y direction side) of the first device base 10. On the first cassette stage 150, a first cassette 150a that accommodates wafers W before processing is placed. On the second cassette stage 151, a second cassette 151a is placed, in which processed wafers W are accommodated.
The first cassette 150a and the second cassette 151a each include a plurality of shelves inside, and each shelf accommodates one wafer W.

Openings (not shown) of the first cassette 150a and the second cassette 151a face in the +Y direction. A robot 155 is arranged on the +Y direction side of these openings. The robot 155 includes a holding surface that holds the wafer W. The robot 155 carries the processed wafer W into the second cassette 151a. Further, the robot 155 takes out the unprocessed wafer W from the first cassette 150a and places it on the temporary placement table 152a of the temporary placement device 152.

The temporary placement device 152 adjusts the position of the temporarily placed wafer W, and is provided at a position adjacent to the robot 155. The temporary storage device 152 has a camera 153 that images the outer periphery of the wafer W near the temporary storage table 152a. Further, the temporary storage device 152 includes a calculation section (not shown). The calculation unit calculates the center position of the wafer W from the captured image of the outer periphery of the wafer W. Furthermore, the calculation unit calculates the distance and direction from the center position of the wafer W to the center position of the chuck table 5. Based on the calculation result, the temporary storage device 152 rotates the temporary storage table 152a on which the wafer W is placed so that the wafer W is at a position where the wafer W can be easily transported to the chuck table 5.

A carry-in mechanism (loading arm) 154a is provided at a position adjacent to the temporary storage device 152. The carry-in mechanism 154a includes a suction pad having a suction surface that suctions and holds the back surface Wb of the wafer W. The carry-in mechanism 154a suction-holds the wafer W temporarily placed on the temporary holding table 152a using a suction pad, transports it to the chuck table 5 located near the temporary holding device 152 in the processing area B, and transfers the wafer W temporarily placed on the temporary holding table 152a to the chuck table 5 located near the temporary holding device 152 in the processing area B. Place it on the surface 50.

The chuck table 5 includes a table surface 50 that attracts the wafer W. The table surface 50 is connected to a suction source (not shown), and can suction-hold the wafer W via the protective tape T. The chuck table 5 is rotatable about a central axis passing through the center of the table surface 50 and extending in the Z-axis direction while holding the wafer W on the table surface 50 .

In this embodiment, four chuck tables 5 are arranged at equal intervals in the circumferential direction on the upper surface of a turntable 6 arranged on the second device base 11. A rotation shaft (not shown) for rotating the turntable 6 is disposed at the center of the turntable 6 . The turntable 6 can rotate around an axis extending in the Z-axis direction by this rotating shaft. As the turntable 6 rotates, the four chuck tables 5 are revolved. Thereby, the chuck table 5 can be sequentially positioned near the temporary placement device 152, below the rough grinding means 30, below the finish grinding means 31, and below the polishing means 4.

A first column 12 is erected at the rear (+Y direction side) of the second device base 11 . On the front surface of the first column 12, a rough grinding means 30 for rough grinding the wafer W and a rough grinding feeding means 20 are arranged.

The rough grinding feed means 20 includes a pair of guide rails 201 parallel to the Z-axis direction, a lifting table 203 that slides on the guide rails 201, a ball screw 200 parallel to the guide rails 201, a motor 202 that rotationally drives the ball screw 200, and , is provided with a holder 204 attached to the front (surface) of the lifting table 203. The holder 204 holds the rough grinding means 30.

The elevating table 203 is slidably installed on the guide rail 201. A nut portion (not shown) is fixed to the rear side (back side) of the lifting table 203. A ball screw 200 is screwed into this nut portion. Motor 202 is connected to one end of ball screw 200.

In the rough grinding feed means 20, the motor 202 rotates the ball screw 200, so that the elevating table 203 moves in the Z-axis direction along the guide rail 201. As a result, the holder 204 attached to the lifting table 203 and the rough grinding means 30 held by the holder 204 also move in the Z-axis direction together with the lifting table 203.

The rough grinding means 30 includes a spindle housing 301 fixed to a holder 204, a spindle 300 rotatably held by the spindle housing 301, a motor 302 that rotationally drives the spindle 300, a wheel mount 303 attached to the lower end of the spindle 300, A grinding wheel 304 is detachably connected to the lower surface of the wheel mount 303.

The spindle housing 301 is held by the holder 204 so as to extend in the Z-axis direction. The spindle 300 extends in the Z-axis direction perpendicularly to the table surface 50 of the chuck table 5, and is rotatably supported by the spindle housing 301.

The motor 302 is connected to the upper end side of the spindle 300. This motor 302 causes the spindle 300 to rotate about a rotation axis extending in the Z-axis direction.
The wheel mount 303 is formed into a disk shape and is fixed to the lower end (tip) of the spindle 300. Wheel mount 303 supports grinding wheel 304.

The grinding wheel 304 is formed to have approximately the same diameter as the wheel mount 303. The grinding wheel 304 includes an annular wheel base (annular base) 304a made of a metal material such as stainless steel. A plurality of approximately rectangular parallelepiped rough grinding wheels 304b are arranged and fixed in an annular manner on the lower surface of the wheel base 304a over the entire circumference. The rough grinding wheel 304b grinds the back surface Wb of the wafer W held on the chuck table 5. The rough grinding whetstone 304b is a whetstone containing relatively large abrasive grains.

A grinding water flow path extending in the Z-axis direction is formed inside the spindle 300, and a grinding water supply means (not shown) communicates with this grinding water flow path (both not shown). The grinding water supplied from the grinding water supply means to the spindle 300 is ejected downward from the opening at the lower end of the grinding water flow path toward the rough grinding wheel 304b, and reaches the contact area between the rough grinding wheel 304b and the wafer W. do.

Further, at the rear of the second device base 11, a second column 13 is erected so as to be adjacent to the first column 12 along the X-axis direction. On the front surface of the second column 13, a finishing grinding means 31 for finishing grinding the wafer W and a finishing grinding feeding means 21 are arranged.

The finish grinding feed means 21 has the same configuration as the rough grinding feed means 20, and can grind and feed the finish grinding means 31 in the Z-axis direction. The finish grinding means 31 has the same configuration as the rough grinding means 30, except that it includes a finish grinding wheel 314b instead of the rough grinding wheel 304b. The finish grinding whetstone 314b is a whetstone containing relatively small abrasive grains.

A third column 14 is erected on one side (-X direction side) of the second device base 11. On the front surface of the third column 14, a polishing means 4 for polishing the surface of the wafer W to be ground, a polishing feed means 25, and a Y-axis direction moving means 24 are arranged.

The Y-axis direction moving means 24 includes a pair of guide rails 241 parallel to the Y-axis direction, a movable plate 243 that slides on the guide rails 241, a ball screw 240 parallel to the guide rails 241, and a motor that rotationally drives the ball screw 240. It is equipped with 242.

The movable plate 243 has a polishing feeding means 25 and a polishing means 4, and is slidably installed on the guide rail 241. A nut portion (not shown) is fixed to the rear side (back side) of the movable plate 243. A ball screw 240 is screwed into this nut portion. Motor 242 is connected to one end of ball screw 240.

In the Y-axis direction moving means 24, the motor 242 rotates the ball screw 240, so that the movable plate 243 moves in the Y-axis direction along the guide rail 241. As a result, the polishing feed means 25 and the polishing means 4 disposed on the movable plate 243 also move in the Y-axis direction together with the movable plate 243.

The polishing feed means 25 includes a pair of guide rails 251 parallel to the Z-axis direction, a lifting table 253 that slides on the guide rails 251, a ball screw 250 parallel to the guide rails 251, a motor 252 that rotationally drives the ball screw 250, and A holder 254 attached to the front (surface) of the lifting table 253 is provided. The holder 254 holds the polishing means 4.

The elevating table 253 is slidably installed on the guide rail 251. A nut portion (not shown) is fixed to the rear side (back side) of the lifting table 253. A ball screw 250 is screwed into this nut portion. Motor 252 is connected to one end of ball screw 250.

In the polishing feed means 25, the motor 252 rotates the ball screw 250, so that the elevating table 253 moves in the Z-axis direction along the guide rail 251. As a result, the holder 254 attached to the elevating table 253 and the polishing means 4 held by the holder 254 also move in the Z-axis direction together with the elevating table 253.

The polishing means 4 includes a spindle housing 41 fixed to a holder 254, a spindle 40 rotatably held by the spindle housing 41, a motor 42 that rotationally drives the spindle 40, a mount 43 attached to the lower end of the spindle 40, and A polishing pad 44 is detachably connected to the lower surface of the mount 43.

The spindle housing 41 is held by the holder 254 so as to extend in the Z-axis direction. The spindle 40 extends in the Z-axis direction perpendicularly to the table surface 50 of the chuck table 5, and is rotatably supported by the spindle housing 41.

The motor 42 is connected to the upper end of the spindle 40. The motor 42 causes the spindle 40 to rotate about a rotation shaft extending in the Z-axis direction. A polishing liquid flow path extending in the axial direction is formed inside the spindle 40 .
The mount 43 is formed into a disk shape and is fixed to the lower end (tip) of the spindle 40. Mount 43 supports polishing pad 44 .

The mount 43 and the polishing pad 44 have a through hole in the center thereof through which a polishing liquid (a polishing liquid containing free abrasive grains or a polishing liquid not containing free abrasive grains) is passed. This through hole communicates with the polishing liquid flow path of the spindle 40 described above.
The diameter of the polishing pad 44 is approximately the same as the diameter of the mount 43 and larger than the diameter of the chuck table 5.

The polished wafer W is unloaded by the unloading mechanism (loading arm) 154b. The unloading mechanism 154b includes a suction pad having a suction surface that suctions and holds the back surface Wb of the wafer W. The unloading mechanism 154b suction-holds the back surface Wb of the wafer W placed on the chuck table 5 after the polishing process using a suction pad. Thereafter, the unloading mechanism 154b unloads the wafer W from the chuck table 5 and transports it to the spinner table 157 of the single-wafer type spinner cleaning unit 156.

The spinner cleaning unit 156 includes a spinner table 157 that holds the wafer W, and a nozzle 158 that sprays cleaning water and dry air toward the spinner table 157.

In the spinner cleaning unit 156, the spinner table 157 holding the wafer W is lowered into the first apparatus base 10. Then, cleaning water is sprayed toward the back surface Wb of the wafer W in the first apparatus base 10, and the back surface Wb is cleaned with a spinner. After that, drying air is blown onto the wafer W to dry the wafer W.

The wafer W cleaned by the spinner cleaning unit 156 is carried into the second cassette 151a by the robot 155.

Next, a method for processing a wafer using the processing apparatus 1 will be described in more detail.
(1) Holding process First, the wafer W is placed on the table surface 50 of the chuck table 5 by the carry-in mechanism 154a, as shown in FIG. Thereafter, the table surface 50 is communicated with a suction source (not shown) to suction and hold the wafer W via the protective tape T. In this way, the wafer W is held by the chuck table 5.

(2) Grinding process (2-1) Rough grinding process After the holding process, as the turntable 6 shown in FIG. will be placed in
Subsequently, the motor 302 of the rough grinding means 30 rotates the spindle 300. This causes the wheel mount 303 and grinding wheel 304 attached to the lower end of the spindle 300 to rotate. In this state, the rough grinding means 30 is ground and fed by the rough grinding feeding means 20 along the Z-axis direction. Furthermore, the chuck table 5 is rotated by a drive source (not shown).

As a result, as shown in FIG. 3, the rough grinding wheel 304b of the grinding wheel 304 rotating in the direction of arrow A1 comes into contact with the back surface (top surface) Wb of the wafer W held on the chuck table 5 rotating in the direction of arrow A2. Then, this back surface Wb is roughly ground.

(2-2) Finish Grinding Step After the rough grinding, the chuck table 5 holding the wafer W is placed below the finish grinding means 31 as the turntable 6 shown in FIG. 1 rotates. Then, as in the rough grinding step, the grinding wheel 304 is rotated, and the finishing grinding means 31 is ground and fed along the Z-axis direction by the finishing grinding feeding means 21. Furthermore, the chuck table 5 is rotated by a drive source (not shown).

As a result, as shown in FIG. 3, the finish grinding wheel 314b of the grinding wheel 304 rotating in the direction of the arrow A1 comes into contact with the back surface Wb of the wafer W held on the chuck table 5 rotating in the direction of the arrow A2. Finish grinding is performed on the back surface Wb.

(3) First polishing step After the final grinding, the turntable 6 shown in FIG. 1 rotates, so that the chuck table 5 holding the wafer W is placed below the polishing means 4.
Subsequently, the motor 42 of the polishing means 4 drives the spindle 40 to rotate. As a result, the mount 43 and polishing pad 44 attached to the lower end of the spindle 40 are rotated. In this state, the polishing means 4 is sent for polishing along the Z-axis direction by the polishing feed means 25. Furthermore, the chuck table 5 is rotated by a drive source (not shown).

As a result, as shown in FIG. 4, the polishing pad 44 rotating in the direction of arrow A1 comes into contact with the back surface Wb of the wafer W held by the chuck table 5 rotating in the direction of arrow A2.
As shown in FIG. 4, the polishing pad 44 includes a disk 45 attached to the mount 43 with bolts (not shown) or the like, and a polishing member 46 bonded to the lower surface of the disk 45. This polishing member 46 contacts the back surface Wb of the wafer W. The polishing member 46 includes, for example, a nonwoven fabric and does not include fixed abrasive grains.

Further, in the polishing means 4, as shown in FIG. 4, the spindle 40 has a polishing liquid flow path SL extending therein. Further, the mount 43 and the polishing pad 44 each have a through hole MH and a through hole PH passing through the center. These polishing liquid channel SL, through hole MH, and through hole PH are communicated along the Z-axis direction.

Further, the polishing liquid flow path SL is connected to a free abrasive grain supply source 101 via a free abrasive grain valve 100. Further, the polishing liquid flow path SL is connected to a polishing liquid supply source 103 via a polishing liquid valve 102.
Note that, without providing the polishing liquid flow path SL extending inside the spindle 40 as described above, a nozzle that sprays the polishing liquid and free abrasive grains toward the polishing surface of the polishing pad may be provided.

Then, in the first polishing step, when the polishing member 46 comes into contact with the back surface Wb of the wafer W, the free abrasive valve 100 and the polishing liquid valve 102 are opened. Therefore, in the first polishing step, free abrasive grains from the free abrasive grain supply source 101 are thrown into the polishing liquid from the polishing liquid supply source 103. Then, the polishing liquid containing free abrasive grains is supplied to the back surface Wb of the wafer W through the polishing liquid flow path SL, the through hole MH, and the through hole PH, and the polishing liquid includes the polishing member 46 of the polishing pad 44 and the back surface Wb of the wafer W. reach the point of contact with.

In this state, the polishing member 46 of the rotating polishing pad 44 is pressed against the back surface Wb of the rotating wafer W. Thereby, the back surface Wb of the wafer W is polished by the polishing member 46.
Note that an oxide film having a thickness of 2 nm to 3 nm is formed on the back surface Wb of the wafer W that has undergone the grinding process before the start of the first polishing process. In the first polishing step, the oxide film on the back surface Wb can be removed by using a polishing liquid containing free abrasive grains.

Note that the processing time of the first polishing step (polishing time in the first polishing step) using the polishing liquid containing free abrasive grains is, for example, 10 seconds. Further, the amount of free abrasive grains added to the polishing liquid for the back surface Wb of the wafer W is a predetermined amount. For example, the content of free abrasive grains in the polishing liquid may be about 0.1-1%. Further, the polishing liquid is supplied at a rate of 0.25 L/min.

Further, the pressing pressure of the polishing pad 44 (polishing member 46) against the back surface Wb of the wafer W in the first polishing step is, for example, 25 kpa.
Further, the rotation speed of the spindle 40, that is, the rotation speed of the polishing member 46 is, for example, 500 rpm, and the rotation speed of the chuck table 5 is, for example, 505 rpm. In this way, by making the rotation speed of the chuck table 5 slightly higher than the rotation speed of the polishing member 46, the polishing liquid and free abrasive grains can be diffused over the entire surface of the polishing pad.

(4) Second polishing process The second polishing process is performed following the first polishing process. In this second polishing step, as shown in FIG. 5, the free abrasive valve 100 is closed while the rotating polishing member 46 is in contact with the back surface Wb of the rotating wafer W. Thereby, the polishing liquid containing no free abrasive grains is supplied to the back surface Wb of the wafer W via the polishing liquid flow path SL, the through holes MH, and the through holes PH.

That is, the second polishing step is a polishing step using a polishing liquid that does not contain free abrasive grains. With such a polishing liquid being supplied to the back surface Wb of the wafer W, the polishing member 46 of the rotating polishing pad 44 is pressed against the back surface Wb of the rotating wafer W to polish this back surface Wb.

Note that the processing time of the second polishing step (polishing time in the second polishing step) using a polishing liquid that does not contain free abrasive grains is, for example, 2 minutes. Further, the polishing liquid is supplied at a rate of 0.25 L/min.
Further, the pressing pressure of the polishing pad 44 (polishing member 46) against the back surface Wb of the wafer W is, for example, 25 kpa.
Further, the rotation speed of the spindle 40, that is, the rotation speed of the polishing member 46 is, for example, 500 rpm, and the rotation speed of the chuck table 5 is, for example, 505 rpm. In this way, by making the rotation speed of the chuck table 5 slightly higher than the rotation speed of the polishing member 46, the polishing liquid and free abrasive grains can be diffused over the entire surface of the polishing pad.

As described above, in this embodiment, in the first polishing step, the oxide film formed on the back surface Wb of the wafer W is removed using a polishing liquid containing free abrasive grains. Furthermore, in the second polishing step, a polishing liquid containing no free abrasive grains is used. In the second polishing step, since the oxide film is removed from the back surface Wb of the wafer W, the reaction between the material of the wafer W (silicon, etc.) and the polishing liquid causes the back surface of the wafer W to be removed without using free abrasive grains. It is possible to polish Wb.

Thereby, the free abrasive grains supplied to the back surface Wb of the wafer W in the first polishing step are washed away from the back surface Wb of the wafer W by the polishing liquid that does not contain free abrasive grains and is used in the second polishing step. Therefore, it is possible to prevent free abrasive grains from entering the gap between the surface Wa, which is the lower surface of the wafer W, and the table surface 50 of the chuck table 5, and from adhering to the surface Wa of the wafer W and the chuck table 5. , can be suppressed.

Further, in the first polishing step, the amount of free abrasive grains added to the polishing liquid is a predetermined amount. As a result, in the first polishing step, the amount of free abrasive grains is too small and an oxide film remains on the back surface Wb of the wafer W, or the amount of free abrasive grains is too large and the second polishing step It is possible to prevent free abrasive grains from remaining afterwards.

Note that as the polishing liquid, for example, the polishing liquid described in Patent Document 2 can be used.
Further, the time for opening the free abrasive grain valve 100 in the first polishing step, that is, the time for introducing the free abrasive grains into the polishing liquid, may be the entire period of the first polishing step or may be a part thereof. That is, in the first polishing step, free abrasive grains may be added to the polishing liquid little by little over a relatively long period of time. Alternatively, a large amount of free abrasive grains may be introduced in a relatively short period of time (for example, immediately after the start of the first polishing step). In either case, the amount of free abrasive grains added to the polishing liquid may be approximately the same amount.

Further, in this embodiment, the polishing liquid is supplied to the back surface Wb of the wafer W via the polishing liquid flow path SL, the through holes MH, and the through holes PH. Alternatively, the polishing liquid may be sprayed upward from the side of the chuck table 5 toward the polishing member 46 of the polishing pad 44. In this case, in the first step, the free abrasive grains may be mixed with the polishing liquid and similarly jetted upward, or separately from the polishing liquid, the free abrasive grains may be mixed into the polishing liquid flow path SL, the through hole MH, and the through hole PH. It may also be supplied to the back surface Wb of the wafer W via the wafer W.

1: processing device, 10: first device base, 11: second device base,
12: first column, 13: second column, 14: third column,
5: Chuck table, 50: Table surface, 6: Turntable,
20: rough grinding feeding means, 30: rough grinding means, 304b: rough grinding wheel,
21: Finish grinding feeding means, 31: Finish grinding means, 314b: Finish grinding wheel,
25: polishing feeding means, 4: polishing means,
40: spindle, 44: polishing pad, 46: polishing member,
MH: through hole, PH: through hole, SL: polishing liquid flow path,
100: Free abrasive grain valve, 101: Free abrasive grain supply source,
102: polishing liquid valve, 103: polishing liquid supply source,
W: Wafer, Wa: Front surface, Wb: Back surface, T: Protective tape

Claims (2)

Wafer processing in which an oxide film formed on the ground surface of a wafer that has been ground to a predetermined thickness with a grinding wheel is removed by polishing using free abrasive grains, a polishing liquid, and a polishing pad that does not contain fixed abrasive grains. A method,
a holding step of holding the wafer by a chuck table;
a grinding step of grinding the wafer held on the chuck table to a predetermined thickness using a grinding wheel;
Supplying the free abrasive grains and the polishing liquid to the surface to be ground of the wafer while rotating the polishing pad and rotating the chuck table holding the wafer at a faster rotation speed than the polishing pad. a first polishing step of pressing the polishing pad against the surface to be ground of the wafer to remove an oxide film on the surface to be ground of the wafer;
While rotating the polishing pad and rotating the chuck table holding the wafer at a faster rotation speed than the polishing pad, the polishing liquid containing no free abrasive is applied to the surface of the wafer to be polished . a second polishing step of polishing the polished surface of the wafer while supplying and pressing the polishing pad against the polished surface of the wafer and flowing the free abrasive grains from the polished surface of the wafer;
wafer processing methods including; In the first polishing step, a predetermined amount of the free abrasive grains is added to the polishing liquid.
The method for processing a wafer according to claim 1.

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