KR102654427B1 - Grinding apparatus - Google Patents

Abstract

(Task) Prevent defects from occurring on the outer periphery of the wafer.
(Solution) The grinding device 1 includes a cleaning nozzle 50A that sprays cleaning water 53 onto the outer periphery Wc of the wafer W held by the holding table 10 rotated by the rotating means 13. , 50B), for example, when rough grinding the wafer W, the cleaning nozzle 50A sprays the cleaning water 53 onto the outer periphery Wc of the wafer W to clean the outer periphery ( The debris 100 attached to Wc can be washed away, and even when finishing grinding the wafer W, cleaning water ( 53) can be ejected and cleaned, for example, when the wafer W is thinned by finishing grinding and the wafer thickness becomes smaller than the debris 100, the debris 100 attached to the outer periphery Wc is removed. There is no fear of being pulled up on the upper surface of the wafer (W). Therefore, defects are prevented from occurring on the outer periphery Wc of the wafer W after thinning.

Description

Grinding device {GRINDING APPARATUS}

The present invention relates to a grinding device for grinding wafers.

A grinding device for grinding a wafer includes a holding table for holding a wafer, and a grinding means on which a grinding wheel to which a grinding wheel is attached that grinds the wafer held on the holding table is rotatably mounted, and the wafer is held in a predetermined position. It can be ground to any thickness. In the grinding device, after replacing the grinding wheel or holding table, the holding surface of the holding table and the grinding surface of the grinding wheel are made parallel, so self-grinding is performed by grinding the holding surface with a grinding wheel (example For example, see Patent Document 1 below).

The holding table is composed of a disc-shaped porous plate and a frame surrounding the porous plate, and the upper surface of the porous plate and the upper surface of the frame are made flush with each other by means of a self-grind. The upper surface of the porous plate serves as a holding surface for holding the wafer. Meanwhile, the upper surface of the frame serves as a measurement surface for measuring the height of the holding surface by contacting a contact-type height measuring unit. In grinding processing, the height of the upper surface of the wafer held by the holding surface is measured, the height of the upper surface of the frame is measured, the thickness of the wafer is calculated from the height difference, and the wafer is ground to the desired thickness. Grinding processing includes rough grinding, in which the wafer is roughly ground, and finish grinding, in which the wafer after rough grinding is reduced to a desired finished thickness. The wafer after finish grinding is thinned to a thickness of, for example, 5 to 10 ㎛. do. Defects may occur on the outer periphery of the final ground wafer. Since the abrasive grains of the grinding wheels used in finish grinding are the cause of defects, as a countermeasure, the grinding wheels for finishing grinding are made of small abrasive grains to prevent defects from occurring on the outer periphery of the wafer.

Japanese Patent Publication No. 2014-237210

However, even if the above measures are taken, although it is possible to reduce the occurrence of defects on the outer periphery of the wafer, it is difficult to completely eliminate the defects.

The present invention has been made in consideration of the above circumstances, and its purpose is to prevent defects from occurring on the outer periphery of the wafer.

The present invention relates to a holding table holding a disk-shaped wafer, a rotating means for rotating the holding table, and a grinding wheel formed by arranging grinding wheels in an annular shape, and grinding the wafer held by the holding table with the grinding wheels. A grinding device including grinding means, which is provided with a cleaning nozzle that sprays cleaning water on the outer periphery of a wafer held by the holding table rotated by the rotating means.

The cleaning nozzle is provided with a jet orifice for spraying the cleaning water on the outer periphery of the wafer held by the holding table, and is a tangent line of the outer periphery of the wafer in the direction from the outer periphery of the wafer held by the holding table to the holding surface. It is preferable to position the cleaning nozzle inward, and to spray the cleaning water on the outer periphery of the wafer with the jet orifice directed downward at a predetermined angle with respect to the holding surface.

In addition, the present invention preferably includes a pressurizing nozzle that sprays cleaning water from above the outer peripheral portion of the wafer where the cleaning nozzle sprays the cleaning water to press the wafer against its holding surface.

The grinding device according to the present invention is provided with a cleaning nozzle that ejects cleaning water on the outer periphery of the wafer held by a holding table rotated by a rotating means. Therefore, for example, when rough grinding a wafer, the wafer is cleaned by the cleaning nozzle. By spraying cleaning water on the outer periphery of the wafer, grinding debris and abrasive particles attached to the outer periphery can be washed away. Also, when finishing grinding a wafer, cleaning water is sprayed on the outer periphery of the wafer after rough grinding using a cleaning nozzle. Because it can be cleaned and grinding debris or abrasive grains do not adhere to the outer periphery of the wafer, there is no fear of grinding debris or abrasive grains being pulled up to the upper surface of the wafer during, for example, final grinding. Therefore, according to the present invention, defects are prevented from occurring on the outer periphery of the wafer after thinning.

The cleaning nozzle is provided with a jet orifice for spraying the cleaning water on the outer periphery of the wafer held by the holding table, and is located in a direction from the outer periphery of the wafer held by the holding table to the holding surface, which is greater than the tangential direction of the outer periphery of the wafer. Since the cleaning nozzle is located on the inside and the spray nozzle is directed downward at a predetermined angle with respect to the holding surface, the cleaning water is sprayed on the outer edge of the wafer, allowing cleaning of the outer edge of the wafer during grinding. The effect can be improved, and defects do not occur on the outer periphery of the wafer after thinning.

In addition, in the present invention, since the cleaning nozzle is provided with a pressurizing nozzle that sprays cleaning water from an upper side of the outer peripheral portion of the wafer that sprays the cleaning water and presses the wafer against the holding surface, the cleaning nozzle has the predetermined pressure. Even if the angle of is set to an angle close to parallel with the holding surface, the outer periphery of the wafer does not rise from the holding table during grinding, and the outer periphery can be cleaned well.

1 is a perspective view showing the configuration of a grinding device.
Fig. 2 is an explanatory diagram showing the grinding area of the grinding wheel and explaining the position of the cleaning nozzle.
Figure 3 is a cross-sectional view showing a state in which a wafer is ground with a grinding wheel while spraying cleaning water from a cleaning nozzle onto the outer periphery of the wafer.
Figure 4 is a cross-sectional view showing a state in which a wafer is ground with a grinding wheel while a cleaning nozzle sprays cleaning water onto the outer periphery of the wafer and a pressure nozzle sprays cleaning water from above the outer peripheral portion of the wafer and pressurizes it. .

The grinding device 1 shown in FIG. 1 is an example of a grinding device that grinds a disk-shaped wafer W, which is a workpiece. The grinding device 1 has a device base 2 extending in the Y-axis direction, and stages 3a and 3b are arranged adjacent to the -Y direction side of the device base 2. A cassette 4a accommodating the wafer W before grinding is placed on the stage 3a, and a cassette 4b accommodating the wafer W after grinding is placed on the stage 3b. At a position facing the cassette 4a and the cassette 4b, a loading/unloading means ( 5) This arrangement is formed. In the movable range of the loading/unloading means 5, a temporary placing means 6 for temporarily placing the wafer W and a cleaning means 7 for cleaning the grinding debris attached to the wafer W after grinding are arranged. there is.

The grinding device 1 includes a rotatable turntable 8, a holding table 10 disposed on the turntable 8 and having a holding surface 11a for holding the wafer W, and the holding table 10 a rotation means (13) for rotating the wafer (W) held on the holding table (10), a grinding means (20A) for performing rough grinding on the wafer (W) held on the holding table (10), and a wafer ( It is provided with grinding means 20B that performs final grinding on W). Near the temporary placement means 6, a first transfer means 9a is provided for transferring the wafer W before grinding temporarily placed on the temporary placement means 6 to the holding table 10. Additionally, in the vicinity of the cleaning means 7, a second transport means 9b is provided for transporting the ground wafer W held on the holding table 10 to the cleaning means 7.

The holding tables 10 are arranged, for example, in an isometric arrangement with the center of the turntable 8 as the center. The holding table 10 is composed of a disk-shaped porous plate 11 and a frame 12 in which the porous plate 11 is accommodated, and the upper surface of the porous plate 11 attracts and holds the wafer W. It consists of a holding surface (11a). The upper surface of the ring-shaped outer peripheral side of the frame 12 surrounding the holding surface 11a of the holding table 10 serves as a reference surface 12a having the same height as the holding surface 11a. A rotation means 13 is connected to the lower end of each holding table 10, and is capable of rotating at a predetermined rotation speed. By rotating the turntable 8, the holding table 10 can rotate. In addition, the holding surface 11a of the holding table 10 is an inclined surface inclined downward in the outer peripheral direction with the center portion as the vertex.

At the end of the device base 2 on the +Y direction side, a column 14a extending in the Z-axis direction is formed standing upright. On the front side of the column 14a, a grinding means 20A is arranged via a grinding transfer means 30A. The grinding means 20A includes a spindle 21 having an axis in the Z-axis direction, a motor 22 connected to one end of the spindle 21, and a spindle housing 23 in which the spindle 21 is rotatably surrounded and supported. ), a holder 24 for holding the spindle housing 23, a grinding wheel 26 mounted at the lower end of the spindle 21 to be freely removable via a mount 25, and a grinding wheel 26 ) is provided with a grinding wheel 27a for rough grinding arranged in an annular shape at the lower part of the . As the grain size of the abrasive grains of the grinding wheel 27a, for example, #600 (average grain size 20 μm) is used. Then, the motor 22 is driven to rotate the spindle 21, thereby allowing the grinding wheel 26 to rotate at a predetermined rotation speed.

The grinding conveying means 30A includes a ball screw 31 extending in the Z-axis direction, a motor 32 connected to one end of the ball screw 31, and a motor 32 that extends parallel to the ball screw 31 and includes a column 14a. ) is provided with a pair of guide rails 33 arranged and formed, and a lifting plate 34 on one side of which is connected to the holder 24. A pair of guide rails 33 are in sliding contact with the other surface of the lifting plate 34, and a ball screw 31 is screwed to a nut formed in the center of the lifting plate 34. By the motor 32 driving the ball screw 31, the grinding means 20A together with the lifting plate 34 can be raised and lowered in the ±Z direction.

At the end of the device base 2 in the +Y direction, a column 14b is formed standing upright with a predetermined gap between the columns 14a and the column 14a. On the front side of the column 14b, a grinding means 20B is arranged via a grinding feed means 30B. The grinding means 20B includes a grinding wheel 26 mounted at the lower end of the spindle 21 to be freely removable via a mount 25, and a finish grinding wheel arranged in an annular manner at the lower part of the grinding wheel 26. It is provided with a grinding wheel 27b, and other than these, it has the same structure as the grinding means 20A. As the abrasive grain size of the grinding wheel 27b, for example, #8000 is used. In the grinding means 20B, the motor 22 is driven to rotate the spindle 21, thereby rotating the grinding wheel 26 at a predetermined rotation speed.

The grinding feed means 30B has the same configuration as the grinding feed means 30A. That is, the grinding conveying means 30B includes a ball screw 31, a motor 32 connected to one end of the ball screw 31, and a motor 32 that extends parallel to the ball screw 31 and is disposed on the column 14b. It is provided with a pair of guide rails 33 and a lifting plate 34 on one side of which is connected to a holder 24, and the motor 32 drives the ball screw 31 to move the lifting plate 34 together. The grinding means 20B can be raised and lowered in the ±Z direction.

At the center of the turntable 8, a support 15 is erected. A case 16 is fixed to the upper surface of the support 15. A thickness measuring means 40A is disposed and formed on the side of the case 16 on the side of the grinding means 20A (-X direction side) to measure the thickness of the wafer W to be roughly ground by the grinding means 20A, A thickness measuring means 40B is disposed on the side of the case 16 on the side of the grinding means 20B (+ The thickness measuring means 40A, 40B are contact-type height gauges, and include a first gauge 41 that measures the height of the upper surface of the wafer W held on the holding surface 11a of the holding table 10, and A second gauge 42 is provided to measure the height of the holding surface 11a of the table 10.

The first gauge 41 has a probe brought into contact with the surface of the object to be measured, and the position of the probe corresponds to the position of the holding surface 11a of the holding table 10. In the first gauge 41, the height when the measurer touches the upper surface of the wafer W held on the holding table 10 can be measured as the upper surface height of the wafer W. The second gauge 42 has a probe brought into contact with the surface of the object to be measured, and corresponds to the position of the reference surface 12a of the holding table 10. In the second gauge 42, the height when the gauge touches the reference surface 12a can be measured as the height of the holding surface of the holding table 10. And, in the thickness measuring means 40A and 40B, the difference between the measured value of the first gauge 41 and the measured value of the second gauge 42 can be calculated as the thickness of the wafer W.

The grinding device (1) is provided with cleaning nozzles (50A, 50B) that spray cleaning water toward the outer periphery (Wc) of the wafer (W) held by the holding table (10) rotated by the rotating means (13). there is. The cleaning nozzle 50A is supported by a support portion 17a formed standing on the outside of the turntable 8 on the grinding means 20A side (-X direction side). The cleaning nozzle 50A is provided with a jet orifice 51 that ejects cleaning water toward the outer periphery Wc of the wafer W held by the holding table 10, and the jet orifice 51 is connected to the cleaning water supply source 52. ) is connected to. The cleaning nozzle 50A can clean the outer periphery Wc of the wafer W during rough grinding of the wafer W by the grinding means 20A. The cleaning nozzle 50B is supported by a support portion 17b formed standing on the outside of the turntable 8 on the grinding means 20B side (+X direction side). The configuration of the cleaning nozzle 50B is the same as that of the cleaning nozzle 50A, and the injection port 51 is connected to the cleaning water supply source 52. The cleaning nozzle 50B can clean the outer periphery Wc of the wafer W during final grinding of the wafer W by the grinding means 20B.

Next, an operation example of the grinding device 1 shown in FIG. 1 will be described. A tape T is attached to the lower surface opposite to the upper surface (to be ground) of the wafer W before grinding, and a plurality of wafers W are accommodated in the cassette 4a. The loading/unloading means 5 takes out one wafer W before grinding from the cassette 4a and temporarily places the wafer W in the temporary placing means 6. After positioning the wafer W in the temporary placement means 6, the wafer W is transferred from the temporary placement means 6 to the holding table 10 by the first transfer means 9a. The holding table 10 suction-holds the wafer W via the tape T on the holding surface 11a on which the suction force of the suction source is applied.

As the turntable 8 rotates, the holding table 10 holding the wafer W is moved below the grinding means 20A. As shown in FIG. 2, the holding table 10 is rotated, for example, in the direction of arrow A by the rotation means 13. Next, while the grinding means 20A is lowered in the -Z direction by the grinding feed means 30A shown in FIG. 1, the grinding means 20A rotates the spindle 21 to move the grinding wheel 27a, for example. It is rotated in the direction of arrow A, and rough grinding is performed while pressing the upper surface of the wafer W with the grinding wheel 27a.

During rough grinding, cleaning water 53 is sprayed from the cleaning nozzle 50A toward the outer periphery Wc of the wafer W for cleaning. Here, as shown in FIG. 2, among the rotational traces of the grinding wheel 27a rotating in the direction of arrow A, the arc-shaped area where the grinding wheel 27a actually contacts the upper surface of the wafer W and performs grinding is grinding. It is in area (P). During rough grinding, the grinding wheel 27a always passes through the center Wo of the wafer W, and the grinding surface of the grinding wheel 27a is in contact with the upper surface of the wafer W in the grinding area P. It is grinding.

When cleaning the outer periphery Wc of the wafer W during rough grinding, the cleaning nozzle 50A is positioned on the wafer W in the direction of the holding surface from the outer periphery of the wafer W held by the holding table 10. ), and the wafer ( It is desirable to spray the washing water 53 onto the outer periphery Wc of W). The cleaning nozzle 50A shown in this embodiment is positioned at the spraying position SP1 slightly inward from the tangential direction of the outer periphery Wc of the wafer W shown in FIG. 2, and is directed by an arrow from the spraying port 51. The washing water 53 is sprayed toward the outer periphery Wc so as to oppose the rotation direction of the wafer W rotating in the A direction.

The position of the cleaning nozzle 50A is not limited to the spray position SP1 described above. For example, the cleaning nozzle 50A may be positioned at a spray position SP2 where the cleaning water 53 can be sprayed along the tangential direction of the outer periphery Wc of the wafer W, and the cleaning nozzle 50A may be positioned at the spray positions SP1 and SP2. ), the cleaning nozzle 50A may be positioned at the spraying position SP3 where the cleaning water 53 can be sprayed toward the outer periphery Wc of the wafer W at a position opposite to ).

As shown in FIG. 3, the predetermined angle at which the cleaning water 53 is sprayed from the injection port 51 of the cleaning nozzle 50A is, for example, downward with respect to the holding surface 11a of the holding table 10. It is set at 45°. By spraying the cleaning water 53 from the spray port 51 of the cleaning nozzle 50A positioned in this way to the outer periphery Wc of the wafer W, rough grinding is performed, thereby forming the outer periphery of the wafer W ( Wash away the debris (100) attached to Wc). The waste 100 contains grinding waste and abrasive grains. The predetermined angle of the cleaning nozzle 50A is not particularly limited, but if the angle is less than 45°, the wafer W is lifted from the holding table 10 by the cleaning water 53 sprayed from the nozzle 51. If the floating angle is greater than 45°, all grinding debris and abrasive grains are not removed from the outer periphery Wc of the wafer W, and the cleaning effect deteriorates. Therefore, the predetermined angle of the cleaning nozzle 50A is preferably 45°, and the cleaning effect of the outer periphery Wc of the wafer W can be improved.

During rough grinding, changes in the thickness of the wafer W are always monitored using the thickness measuring means 40A shown in FIG. 1, and rough grinding is terminated when the wafer W reaches the desired thickness. Additionally, the thickness of the wafer W after rough grinding is set to 100 to 200 μm. Additionally, the debris 100 generated during rough grinding is 10 to 20 μm. After that, the turntable 8 further rotates, and the holding table 10 holding the wafer W after rough grinding is moved below the grinding means 20B. By rotating the holding table 10, the grinding means 20B rotates the spindle 21 and rotates the grinding grindstone 27b at a predetermined rotation speed, and the grinding means (30B) rotates the grinding means ( 20B) is lowered, for example, in the -Z direction, and the upper surface of the wafer W is finish-grinded with the rotating grinding wheel 27b until the desired finished thickness is reached. In the case of finish grinding by the grinding means 20B, similarly to the grinding means 20A, the grinding wheel 27b contacts the upper surface of the wafer W in the grinding area P shown in FIG. 2 to finish. Carry out grinding. In addition, the desired finished thickness is set to, for example, 5 to 10 μm.

Even in the case of cleaning the outer periphery Wc of the wafer W during final grinding, the cleaning nozzle 50B is positioned at the spray position SP1 shown in FIG. 2, and the holding table shown in FIG. 3 ( The washing water 53 is jetted onto the outer periphery Wc of the wafer W with the jet nozzle 51 directed downward at, for example, 45° with respect to the holding surface 11a of 10). By spraying the cleaning water 53 from the injection port 51 of the cleaning nozzle 50B positioned in this way to the outer periphery Wc of the wafer W, final grinding is performed, thereby forming the outer periphery of the wafer W ( Wc) is washed. During final grinding, much of the debris 100 is removed from the outer periphery Wc. However, even if the debris 100 generated during rough grinding remains on the outer periphery Wc, it is washed away with the washing water 53. I can pay it. During the final grinding, the change in the thickness of the wafer W is always monitored using the thickness measuring means 40B shown in FIG. 1, and the final grinding is terminated when the wafer W reaches the desired finished thickness. Additionally, the cleaning nozzle 50B may be positioned at the spray position SP2 or SP3.

In this way, the grinding device 1 according to the present invention performs cleaning by spraying the cleaning water 53 on the outer periphery Wc of the wafer W held by the holding table 10 rotated by the rotating means 13. Since the nozzles 50A and 50B are provided, when the wafer W is roughly ground by the grinding means 20A, the cleaning nozzle 50A applies the cleaning water 53 to the outer periphery Wc of the wafer W. The debris 100 attached to the outer periphery (Wc) can be washed off by spraying. Also, when the wafer W is subjected to final grinding with the grinding means 20B, the cleaning nozzle 50B sprays the cleaning water 53 on the outer periphery Wc of the wafer W that has been roughly ground to clean it. Therefore, for example, when the wafer W is thinned by final grinding and the wafer thickness becomes smaller than the debris 100, the debris 100 attached to the outer periphery Wc is attached to the upper surface of the wafer W. There is no fear of being pulled up. Therefore, according to the present invention, defects are prevented from occurring in the outer periphery Wc of the wafer W after thinning.

For example, as shown in FIG. 4 , the grinding device 1 sprays cleaning water ( 62) may be provided with a pressure nozzle 60 that ejects pressure to press the wafer W against the holding surface 11a. The pressure nozzle 60 has an injection port 61 that sprays the washing water 62, and is positioned immediately above the outer periphery Wc of the wafer W. In the example of FIG. 4, the predetermined angle at which the cleaning water 53 is sprayed from the injection port 51 of the cleaning nozzle 50A (50B) is, for example, relative to the holding surface 11a of the holding table 10. The direction is set to 25°. Cleaning water 53 is sprayed from the spray port 51 of the cleaning nozzle 50A (50B) positioned in this way to the outer periphery Wc of the wafer W to clean it, and pressurized toward this outer peripheral portion. Washing water 62 is jetted from the injection port 61 of the nozzle 60 to press the outer periphery Wc against the holding surface 11a, while removing debris 100 attached to the outer periphery Wc of the wafer W. ) can be washed away, and the wafer (W) can be subjected to rough grinding and final grinding.

In this way, when the grinding device 1 is provided with the pressure nozzle 60, the cleaning water 62 can be sprayed from the pressure nozzle 60 to press the wafer W downward, so that the cleaning nozzle 50A Even if the predetermined angle of (50B)) is set to an angle smaller than 45°, the outer periphery Wc of the wafer W does not rise from the holding table during grinding, and the outer periphery Wc can be cleaned well. there is.

The present invention can also be applied in the case where processing (edge trimming) is performed to grind and remove the chamfered portion of the outer periphery (Wc) of the wafer (W) before rough grinding or final grinding of the wafer (W). there is. That is, when edge trimming is performed on the outer periphery Wc of the wafer W, the outer periphery Wc of the wafer W may be cleaned by spraying washing water from a cleaning nozzle.

The grinding device 1 shown in the above embodiment is a two-axis device with two grinding means 20A and 20B, but is not limited to this device configuration and can also be a single-axis device with one grinding means. The invention can be applied.

1: Grinding device
2: device base
3a, 3b: stage
4a, 4b: Cassette
5: Means of entry and exit
6: Temporary wit table
7: Cleaning means
8: Turntable
9a: First conveyance means
9b: Second conveyance means
10: Holding table
11: Porus plate
12: frame
13: means of rotation
14a, 14b: column
15: Holder
16: case
17a, 17b: support part
20A, 20B: Grinding means
21: spindle
22: motor
23: spindle housing
24: Holder
25: Mount
26: grinding wheel
27a, 27b: grinding wheel
30A, 30B: Grinding transport means
31: ball screw
32: motor
33: Guide rail
34: Elevating plate
40A, 40B: means of measuring thickness
41: 1st gauge
42: 2nd gauge
50A, 50B: Cleaning nozzle
51: nozzle
52: Cleaning water source
53: washing water
60: Pressurized nozzle
61: Nozzle
62: Washing water

Claims (3)

A holding table for holding a disk-shaped wafer, a rotating means for rotating the holding table, and a grinding means for rotating a grinding wheel formed by arranging grinding wheels in an annular shape and grinding the wafer held by the holding table with the grinding wheels. A grinding device comprising:
The grinding wheel is in contact with the radius portion of the wafer,
It is provided with a cleaning nozzle that sprays cleaning water to wash away debris remaining on a portion of the outer periphery of the wafer held by the holding table rotated by the rotating means that is not in contact with the grinding wheel, and
The spray direction of the cleaning water sprayed from the cleaning nozzle is a direction tangential to the outer circumference of the wafer at the outer periphery of the grinding wheel and a direction opposite to the rotation direction of the holding table,
Additionally, the grinding device is provided with a pressurizing nozzle that sprays cleaning water from above the outer peripheral portion of the wafer where the cleaning water is sprayed by the cleaning nozzle and presses the outer peripheral portion of the wafer against the holding surface. delete delete

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