JP2022083700A - Wafer processing method - Google Patents

Abstract

To prevent chipping of a wafer resulting from a residual of a notch chamfering part.SOLUTION: A wafer processing method for processing a wafer in which an outer periphery has a chamfering part, a notch is formed in an outer peripheral edge, and a notch chamfering part is formed in the notch comprises an outer periphery chamfering part removing step, a protrusion holding step, a notch cutting step, and a rear surface grinding step. The outer periphery chamfering part removing step removes a chamfering part of an outer periphery at a depth deeper than a finishing thickness of the wafer from a surface of the wafer. The protrusion holding step positions the wafer on a holding surface at a position at which the notch protrudes outside an outer peripheral edge of a holding table, and holds the wafer on the holding table . The notch cutting step cuts the notch by a rotating cutting blade. The rear surface grinding step sticks a protective tape to the surface of the wafer and thins the wafer to the finishing thickness by grinding the wafer from a rear surface of the wafer.SELECTED DRAWING: Figure 5

Description

The present invention relates to a wafer processing method for processing a wafer having a chamfered portion on the outer periphery, a notch formed on the outer peripheral edge, and a notch chamfered portion formed on the notch.

In the manufacturing process of device chips used in electronic devices such as mobile phones and personal computers, first, a plurality of planned division lines (streets) intersecting each other are set on the surface of a wafer made of a material such as a semiconductor. Then, devices such as ICs (Integrated Circuits) and LSIs (Large-scale Integration) are formed in each area partitioned by the planned division line. Then, when the wafer is ground from the back surface side to be thinned and divided along the planned division line, individual device chips are formed.

A notch called a notch indicating the crystal orientation of the wafer is formed on the outer peripheral edge of a wafer such as a silicon wafer on which a device is formed. Then, in various steps of the wafer processing process, the processing position and the like are determined with reference to this notch. Further, on the outer periphery of the wafer, an arcuate chamfered portion extending from the front surface to the back surface of the wafer is formed in order to prevent the end portion from being chipped or the like.

Here, when a wafer having a chamfered portion formed on the outer periphery is ground from the back surface side to be thinned, a knife edge shape formed by an arc surface and a ground surface is formed on the outer periphery of the wafer, and the outer periphery of the wafer is likely to be chipped. Become. Therefore, before grinding the wafer, an edge trimming process is performed in which an annular cutting blade is cut in the outer periphery of the wafer to remove the chamfered portion (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-173961

When edge trimming is performed using a cutting blade with a large blade thickness so that the chamfered portion on the outer periphery can be reliably removed, the notch cannot be referred to in the subsequent steps when all the notches are removed. Therefore, it is conceivable to perform edge trimming so that the notch partially remains.

However, since the notch is also chamfered in advance to form a notch chamfered portion, when the wafer is ground with the notch partially remaining on the wafer, the notch chamfered portion and the ground surface form a knife edge shape. It is formed. Therefore, the notch is likely to be chipped.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a wafer processing method capable of preventing wafer chipping due to residual notch chamfered portion.

According to one aspect of the present invention, there is a method for processing a wafer having a chamfered portion on the outer periphery, a notch formed on the outer peripheral edge, and a notch chamfered portion formed on the notch. The wafer is positioned on the holding surface so that the entire area overlaps with the holding surface of the holding table, and after the whole area holding step of holding the wafer on the holding table and the whole area holding step, the surface of the wafer is used for the wafer. Before or after the outer peripheral chamfer removal step for removing the chamfered portion of the outer periphery at a depth deeper than the finish thickness, and the entire area holding step and the outer peripheral chamfering portion removing step, the notch is larger than the outer peripheral edge of the holding table. A protrusion holding step in which the wafer is positioned on the holding surface at a position protruding outward and the wafer is held by the holding table, and a notch cutting step in which a rotating cutting blade cuts into the notch after the protrusion holding step. After the outer peripheral chamfer removal step and the notch notch step, a protective tape is attached to the front surface of the wafer, and the wafer is ground from the back surface side to thin the wafer to the finish thickness. A method for processing a wafer is provided.

Preferably, the cutting blade and the holding table are relatively movable in a feed direction parallel to the holding surface of the holding table, and in the overhang holding step, the center of the holding surface and the wafer are of the same. The wafer is positioned on the holding surface so that the notches are aligned along the feeding direction, and in the notch cutting step, the cutting blade and the holding table are relatively moved along the feeding direction. The cutting blade is cut into the notch toward the center of the wafer.

Further, preferably, the holding table is internally provided with a first suction path leading to a first region of the holding surface and a second suction path leading to a second region of the holding surface. In the whole area holding step, the wafer is sucked into the holding table through the first suction path and the second suction path, and in the protrusion holding step, the wafer is sucked through the first suction path. It is sucked into the holding table and is not sucked into the holding table through the second suction path.

In the wafer processing method according to one aspect of the present invention, before the wafer is ground from the back surface side to thin the wafer, the chamfered portion formed on the outer periphery of the wafer is removed, and the notch is cut by the cutting blade. , Is carried out. As a result, the notch chamfered portion is removed together with the chamfered portion on the outer periphery of the wafer, so that when the wafer is subsequently ground and thinned, the knife edge shape due to the notch chamfered portion does not occur.

Therefore, according to one aspect of the present invention, there is provided a method for processing a wafer that can prevent the wafer from being chipped due to the remaining notch chamfered portion.

It is a perspective view which shows the wafer schematically. It is a perspective view which shows typically the cutting apparatus. FIG. 3A is a top view schematically showing the entire area holding step, FIG. 3B is a top view schematically showing the outer peripheral chamfer removal step, and FIG. 3C is a protrusion. It is a top view schematically showing a holding step, and FIG. 3D is a top view schematically showing a notch cutting step. FIG. 4A is a side view schematically showing the entire area holding step, FIG. 4B is a side view schematically showing the outer peripheral chamfer removal step, and FIG. 4C is a protrusion. FIG. 4D is a side view schematically showing a holding step, and FIG. 4D is a side view schematically showing a notch cutting step. 5 (A) is a perspective view schematically showing the whole area holding step, FIG. 5 (B) is a perspective view schematically showing the outer peripheral chamfer removal step, and FIG. 5 (C) is a protrusion. It is a perspective view schematically showing a holding step, and FIG. 5D is a perspective view schematically showing a notch notch step. It is a perspective view which shows typically the back surface grinding step. It is a flowchart explaining the flow of each step of the wafer processing method.

A method for processing a wafer according to an aspect of the present invention will be described with reference to the accompanying drawings. First, a wafer to be a workpiece to be processed by the wafer processing method according to the present embodiment will be described. FIG. 1 is a perspective view of the wafer 1. The wafer 1 is a disk-shaped wafer made of a material such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor.

The surface 1a of the wafer 1 is partitioned by a plurality of scheduled division lines 3 that intersect each other. Then, a device 5 such as an IC or an LSI is formed in each region of the surface 1a of the wafer 1 partitioned by the planned division line 3. When the wafer 1 is ground from the back surface 1b side to be thinned and the wafer 1 is divided along the planned division line 3, individual device chips are formed.

In order to prevent chipping and cracking at the end of the wafer 1, a chamfered portion (not shown) with corners cut off is formed on the outer peripheral 1c of the wafer 1. The cross-sectional shape of the chamfered portion is, for example, an arc shape extending from the front surface 1a to the back surface 1b. Further, a chip called a notch 1d indicating the crystal orientation of the members constituting the wafer 1 is formed on the outer peripheral edge of the wafer 1. The notch 1d is also chamfered in advance to form a notch chamfered portion (not shown).

The electrical characteristics of a semiconductor element such as a transistor forming a plurality of devices 5 formed on the wafer 1 may change depending on the relationship between the channel direction and the crystal orientation of the semiconductor material. Further, the ease of partitioning the wafer 1 may change depending on the relationship between the planned partition line 3 and the crystal orientation of the semiconductor material constituting the wafer 1. Therefore, the notch 1d is referred to when setting the planned division line 3 on the wafer 1, forming the device 5, dividing the wafer 1, and the like.

When the wafer 1 having the chamfered portion formed on the outer peripheral portion 1c is ground as it is from the back surface 1b side to be thinned, a knife edge shape formed by the chamfered portion and the surface to be ground is formed in the cross-sectional shape of the wafer 1 on the outer peripheral portion 1c. Therefore, the outer circumference 1c of the wafer 1 that has been ground and thinned is likely to be chipped. Therefore, before grinding the wafer 1, a process called edge trimming is performed on the wafer 1 by cutting the outer circumference 1c of the wafer 1 to remove the chamfered portion.

FIG. 2 is a perspective view schematically showing a cutting device 2 used for edge trimming. Next, the cutting device 2 will be described. The cutting device 2 includes a base 4 that supports each component. An opening 4a is formed at a corner of the base 4, and the opening 4a is provided with a cassette mounting table 6 that can be raised and lowered. A cassette 8 for accommodating a plurality of wafers 1 to be a workpiece is placed on the cassette mounting table 6.

A long opening 4b is formed on the side of the opening 4a in the X-axis direction (front-back direction, feed direction). A ball screw type X-axis moving mechanism (feed unit) 12 for moving the X-axis moving table (not shown) in the X-axis direction is arranged in the opening 4b. A table cover 12a is arranged above the X-axis moving table. Further, bellows-shaped dust-proof and drip-proof covers 12b are attached to the front and back of the table cover 12a.

A holding table (chuck table) 14 for holding the wafer 1 is arranged on the upper part of the X-axis moving table so as to be exposed from the table cover 12a. The holding table 14 is connected to a rotation drive source (not shown) such as a motor, and rotates around a rotation axis substantially parallel to the Z-axis direction (vertical direction, cut feed direction). Further, the holding table 14 is moved in the X-axis direction by the X-axis moving mechanism 12 described above (machining feed).

The upper surface of the holding table 14 is a holding surface 14a for holding the wafer 1. The holding surface 14a is connected to a suction source (not shown) via a suction path (not shown) formed inside the holding table 14.

Above the opening 4b, a pair of guide rails 16 are provided which are approached and separated while maintaining a state parallel to the Y-axis direction (left-right direction, indexing feed direction). Each of the pair of guide rails 16 has a support surface that supports the wafer 1 from below and a side surface that is substantially perpendicular to the support surface, and X-axis the wafer 1 drawn out from the cassette 8 placed on the cassette mounting table 6. It is sandwiched in the direction and adjusted to the specified position.

Above the base 4, a gate-shaped first support structure 18 is arranged so as to straddle the opening 4b. A rail 20 along the Y-axis direction is fixed to the front surface (the surface on the guide rail 16 side) of the first support structure 18, and the transfer unit 24 is connected to the rail 20 via a moving mechanism 22 or the like. ..

For example, the transfer unit 24 comes into contact with the upper surface of the wafer 1 to attract the wafer 1, moves up and down by the moving mechanism 22, and moves along the rail 20 in the Y-axis direction. A gripping mechanism 26 for gripping the wafer 1 is provided on the opening 4a side of the transport unit 24.

For example, if the wafer 1 is gripped by the gripping mechanism 26 and the transfer unit 24 is moved in the Y-axis direction, the wafer 1 is pulled out from the cassette 8 mounted on the cassette mounting table 6 to a pair of guide rails 16 or The wafer 1 on the pair of guide rails 16 can be inserted into the cassette 8. After aligning the positions of the wafers 1 with the pair of guide rails 16, the transfer unit 24 sucks the wafers 1 and carries the wafers 1 to the holding table 14.

In the cassette mounting table 6, the height of the wafer 1 to be carried out matches the height of the guide rail 16, or the height of the accommodation position of the wafer 1 in the cassette 8 is the height of the guide rail 16. Ascend and descend in advance to suit.

A gate-shaped second support structure 32 is arranged behind the first support structure 18. On the front surface of the second support structure 32 (the surface on the side of the first support structure 18), two sets of cutting units 36a and 36b are provided via a Y-axis Z-axis movement mechanism (indexing feed unit and cutting feed unit) 34, respectively. It is provided. The cutting units 36a and 36b move in the Y-axis direction (index feed) and move in the Z-axis direction (cut feed) by the corresponding Y-axis Z-axis movement mechanism 34, respectively.

The cutting units 36a and 36b are provided with spindles 50a and 50b (see FIGS. 3A, 3C, etc.) which are rotation axes substantially parallel to the Y-axis direction, respectively. An annular cutting blade 38a, 38b is mounted on one end side of each spindle 50a, 50b. A rotary drive source (not shown) such as a motor is connected to the other end side of each spindle 50a, 50b, and the rotary drive source is the spindle housings 48a, 48b (FIGS. 3A and 3C). Etc.).

Further, a nozzle for supplying a cutting liquid such as pure water to the wafer 1 and the cutting blades 38a and 38b is arranged near the cutting blades 38a and 38b. The wafer 1 can be cut by cutting the rotated cutting blades 38a and 38b into the wafer 1 held on the holding table 14 while supplying the cutting fluid from this nozzle.

An imaging unit (camera) 40 for imaging the wafer 1 held on the holding table 14 is provided at a position adjacent to the cutting units 36a and 36b. The image pickup unit 40 also moves in the Y-axis direction and also moves in the Z-axis direction by the Y-axis Z-axis movement mechanism 34.

A cleaning unit 42 is arranged in the opening 4c provided at a position opposite to the opening 4a with respect to the opening 4b. The cleaning unit 42 includes a spinner table 44 that holds the wafer 1 in a cylindrical cleaning space. A rotation drive source (not shown) for rotating the spinner table 44 at a predetermined speed is connected to the lower portion of the spinner table 44.

Above the spinner table 44, an injection nozzle 46 that injects a cleaning fluid (typically, a mixed fluid in which water and air are mixed) toward the wafer 1 held by the spinner table 44 is arranged. There is. The wafer 1 can be cleaned by rotating the spinner table 44 holding the wafer 1 and injecting a cleaning fluid from the injection nozzle 46.

After the wafer 1 is cut by the cutting units 36a and 36b, the wafer 1 is adsorbed by the transfer unit 24 and the wafer 1 is carried into the cleaning unit 42. After cleaning the wafer 1 with the cleaning unit 42, the wafer 1 is adsorbed by the transfer unit 24 and mounted on the pair of guide rails 16, and then the wafer 1 is mounted on the cassette mounting table 6 by the gripping mechanism 26. To be housed in.

When performing edge trimming by cutting the outer peripheral 1c of the wafer 1 held by the holding table 14, the cutting blade 38b cuts into the end of the outer peripheral 1c of the wafer 1 in the Y-axis direction. First, the X-axis moving mechanism 12 is operated to move the holding table 14 and the Y-axis Z-axis moving mechanism 34 so that the cutting blade 38b is positioned on the tangent line at the end of the outer peripheral 1c of the wafer 1. Move the cutting blade 38b.

After that, the cutting blade 38b is rotated and the holding table 14 is moved to cut the cutting blade 38b into the end portion of the outer peripheral portion 1c of the wafer 1. Then, the holding table 14 is rotated around the Z axis, and the entire outer circumference 1c of the wafer 1 is cut by the cutting blade 38b. Then, the chamfered portion of the outer peripheral portion 1c of the wafer 1 is removed.

Here, if the blade thickness of the cutting blade 38b used for edge trimming of the wafer 1 is increased and all the notches 1d are removed at the time of edge trimming, the notch 1d cannot be referred to in the subsequent steps. Therefore, it is conceivable to partially leave the notch 1d. However, when the wafer 1 is ground and thinned with the notch 1d partially remaining on the wafer 1, a knife edge shape is formed by the notch chamfered portion and the ground surface formed on the notch 1d. In this case, the notch 1d tends to cause the wafer 1 to be chipped.

Therefore, in the processing method of the wafer 1 according to the present embodiment, edge trimming is performed to remove the chamfered portion of the outer peripheral portion 1c, and the cutting blade 38a cuts into the notch 1d to remove the chamfered portion of the notch 1d. Hereinafter, each step of the wafer 1 processing method according to the present embodiment will be described. FIG. 7 is a flowchart showing the flow of each step of the processing method of the wafer 1 according to the present embodiment.

In the processing method of the wafer 1 according to the present embodiment, first, in order to remove the chamfered portion of the outer peripheral portion 1c of the wafer 1, the whole area holding step S10 and the outer peripheral chamfered portion removing step S20 are carried out.

3A is a top view schematically showing the whole area holding step S10, FIG. 4A is a side view schematically showing the whole area holding step S10, and FIG. 5A is a side view schematically showing the whole area holding step S10. It is a perspective view which shows typically the holding step S10. In FIG. 3A, the device 5 formed on the surface of the wafer 1 is omitted for convenience of explanation.

In the whole area holding step S10, for example, the holding surface 14a overlaps the center 1f of the wafer 1 (see FIG. 3A) and the center 14b of the holding surface 14a of the holding table 14 (see FIG. 3A). The wafer 1 is positioned on top, and the wafer 1 is held by the holding table 14. For example, when the wafer 1 housed in the cassette 8 is placed on the holding surface 14a of the holding table 14, the positions of the center 1f of the wafer 1 and the center 14b of the holding surface 14a are aligned.

The alignment of the center 1f of the wafer 1 and the center 14b of the holding surface 14a in the X-axis direction is performed by, for example, the X-axis moving mechanism (feed unit) 12. Further, the alignment in the Y-axis direction is performed by, for example, the transport unit 24. After the alignment of the wafer 1 is completed, the wafer 1 is sucked and held by the holding table 14.

Further, by operating the Y-axis Z-axis moving mechanism 34, as shown in FIG. 5 (A), on the tangent line 1g of the outer peripheral 1c of the wafer 1 at the end 1e in the Y-axis direction of the wafer 1 held by the holding table 14. The cutting blade 38b is positioned at. Here, the height position of the lower end of the cutting blade 38b is set to a height position equal to or higher than the finished thickness of the wafer 1 and lower than the surface 1a of the wafer 1.

In the outer peripheral chamfering portion removing step S20 performed after the entire area holding step S10, the outer peripheral chamfered portion is removed from the surface 1a of the wafer 1 at a depth deeper than the finish thickness of the wafer 1. FIG. 3B is a top view schematically showing the outer peripheral chamfering portion removing step S20, FIG. 4B is a side view schematically showing the outer peripheral chamfering portion removing step S20, and FIG. 5B. ) Is a perspective view schematically showing the outer peripheral chamfering portion removing step S20. In FIG. 3B, the device 5 formed on the surface of the wafer 1 is omitted for convenience of explanation.

In the outer peripheral chamfer removal step S20, the spindle 50b is rotated by the rotary drive source housed in the spindle housing 48b, and the cutting blade 38b is rotated. Then, the X-axis moving mechanism 12 is operated to move the holding table 14 along the X-axis direction, and the cutting blade 38b is cut into the end portion 1e of the wafer 1 held by the holding table 14.

Next, the holding table 14 is rotated once around an axis perpendicular to the holding surface 14a. Then, the outer peripheral 1c of the wafer 1 is cut by the cutting blade 38b, and the chamfered portion of the outer peripheral 1c is removed. Here, when the lower end of the cutting blade 38b is not positioned at a height lower than the back surface 1b of the wafer 1, a portion close to the back surface 1b of the chamfered portion remains.

However, if the lower end of the cutting blade 38b is positioned at a height lower than the surface 1a of the wafer 1 above the finished thickness of the wafer 1, the outer circumference 1c is deeper than the surface 1a of the wafer 1 and is deeper than the finished thickness. The chamfered portion is removed. In this case, when the wafer 1 is finally ground from the back surface 1b side and thinned, the chamfered portion of the outer peripheral portion 1c does not remain, so that the knife edge shape does not occur in the cross section of the wafer 1.

As described above, when the entire area holding step S10 and the outer peripheral chamfering portion removing step S20 are performed, the edge trimming of the wafer 1 can be performed. In the whole area holding step S10, the center 1f of the wafer 1 and the center 14b of the holding surface 14a do not have to be exactly overlapped with each other. If the chamfered portion of the outer peripheral 1c of the wafer 1 can be removed in the outer peripheral chamfering portion removing step S20, the deviation between the center 1f of the wafer 1 and the center 14b of the holding surface 14a is allowed in the whole area holding step S10. ..

Further, in the whole area holding step S10, the center 1f of the wafer 1 and the center 14b of the holding surface 14a may be largely deviated from each other. When the outer peripheral chamfer removal step S20 is performed, the image pickup unit 40 images three or more points on the outer peripheral 1c of the wafer 1 held by the holding table 14, and the XY coordinates of three or more points on the outer peripheral 1c of the wafer 1 are obtained. To detect. Then, the XY coordinates of the center 1f of the wafer 1 can be calculated as the center of the circle passing through these three points or more.

Then, in the whole area holding step S10, when the holding table 14 is rotated around the rotation axis passing through the center 14b of the holding surface 14a, the holding table 14 and the cutting unit 36b are rotated so that the wafer 1 rotates around the center 1f. Move relatively on the XY plane. More specifically, the X-axis moving mechanism 12 is operated so as to cancel the fluctuation of the center 1f of the wafer 1 in the X-axis direction with respect to the center 14b of the holding surface 14a, and the fluctuation of the center 1f with respect to the center 14b in the Y-axis direction is performed. The Y-axis Z-axis movement mechanism 34 is operated so as to cancel each other out.

As described above, in the whole area holding step S10, even when the center 14b of the holding surface 14a and the center 1f of the wafer 1 do not match, the outer peripheral chamfering portion removing step S20 can be appropriately performed. In the whole area holding step S10, the wafer 1 may be positioned on the holding surface 14a so that the entire area of the wafer 1 overlaps the holding surface 14a of the holding table 14, and the wafer 1 may be held by the holding table 14.

Before or after the whole area holding step S10 and the outer peripheral chamfer removing step S20, the protrusion holding step S30 and the notch notch step S40 are carried out. That is, the notch 1d of the wafer 1 is cut and the notch chamfered portion is removed. Next, the protrusion holding step S30 and the notch notch step S40 will be described.

FIG. 3C is a top view schematically showing the protrusion holding step S30, FIG. 4A is a side view schematically showing the protrusion holding step S30, and FIG. 5A is a side view schematically showing the protrusion holding step S30. It is a perspective view which shows typically the holding step S30. In FIG. 3A, the device 5 formed on the surface 1a of the wafer 1 is omitted for convenience of explanation.

In the protrusion holding step S30, the wafer 1 is positioned on the holding surface 14a at a position where the notch 1d of the wafer 1 protrudes outside the outer peripheral edge of the holding table 14, and the wafer 1 is held by the holding table 14. When the whole area holding step S10 and the outer peripheral chamfering portion removing step S20 are performed first, in the protrusion holding step S30, first, the suction holding of the wafer 1 by the holding table 14 is temporarily released, and the position of the wafer 1 is changed. do.

In the protrusion holding step S30, for example, the wafer 1 is positioned on the holding surface 14a so that the center 14b of the holding surface 14a and the notch 1d of the wafer 1 are aligned along the X-axis direction (feeding direction). At this time, it is necessary to adjust the orientation of the wafer 1 so that the notch 1d is located at the end of the wafer 1 in the X-axis direction. For example, the holding table 14 may be rotated around an axis perpendicular to the holding surface 14a to adjust the orientation of the wafer 1.

When adjusting the orientation of the wafer 1, it is necessary for the cutting device 2 to detect the position of the notch 1d. For example, the image pickup unit 40 may be used to detect the position of the notch 1d of the cutting device 2. Alternatively, the transfer unit 24 may be provided with a camera (not shown) for detecting the position of the notch 1d, and the cutting device 2 is notched by this camera in the process of transferring the wafer 1 to the holding table 14 by the transfer unit 24. The position of 1d may be detected.

Then, in the protrusion holding step S30, the wafer 1 is positioned on the holding surface 14a at a position where the notch 1d of the wafer 1 protrudes outside the outer peripheral edge of the holding table 14. At this time, it is preferable that the entire area of the notch 1d does not overlap with the holding surface 14a of the holding table 14, and the entire area of the region cut by the cutting blade 38a in the notch cutting step S40 described below does not overlap with the holding surface 14a. More preferred.

After adjusting the position in this way and placing the wafer 1 on the holding surface 14a, the wafer 1 is sucked and held by the holding table 14. Here, if the entire area of the holding surface 14a is not covered with the wafer 1 and the porous member constituting the holding surface 14a is exposed, the negative pressure acting on the wafer 1 leaks and the holding table 14 is the wafer 1. The force to suck and hold the wafer may decrease.

Therefore, the holding table 14 may be provided with two mutually independent suction paths leading to the holding surface 14a. The first suction path leads to the first region of the holding surface 14a that is covered with the wafer 1 in the protruding holding step S30, and the second suction path is different from the first region of the holding surface 14a. It is good to be familiar with the area 2.

In this case, in the whole area holding step S10, the wafer 1 may be sucked into the holding table 14 through the first suction path and the second suction path. Then, in the protrusion holding step S30, the wafer 1 may be sucked into the holding table 14 through the first suction path. This prevents the leakage of negative pressure. At this time, the wafer 1 is not sucked into the holding table 14 through the second suction path. For example, the first region of the holding surface 14a to which the first suction path is connected is, for example, an arcuate region along the outer peripheral edge of the holding surface 14a.

However, the shape of the first region and the second region of the holding surface 14a is not limited to this, and the holding table 14 can sufficiently suck and hold the wafer 1 in the notch cutting step S40 described below. It may be in shape. Further, the holding table 14 does not have to be provided with two suction paths as long as the wafer 1 can be sufficiently sucked and held even if the negative pressure leaks.

In the protrusion holding step S30, as shown in each figure, the position of the cutting blade 38a is positioned at a predetermined preparation position. For example, when the cutting blade 38a is cut into the notch 1d from the X-axis direction (feeding direction) in the protrusion holding step S30, the X-axis is such that the cutting blade 38a and the notch 1d are aligned along the X-axis direction (feeding direction). The moving mechanism (feed unit) 12 is operated. Further, the Y-axis Z-axis movement mechanism 34 is operated so that the height positions of the spindle 50a and the notch 1d match.

Next, the notch cutting step S40 performed after the protrusion holding step S30 will be described. In the notch cutting step S40, a rotating cutting blade 38a cuts into the notch 1d and a part of the wafer 1 is removed.

3 (D) is a top view schematically showing the notch notch step S40, FIG. 4 (D) is a side view schematically showing the notch notch step S40, and FIG. 5 (D) is a notch. It is a perspective view which shows typically the cut step S40. In FIG. 3D, the device 5 formed on the surface of the wafer 1 is omitted for convenience of explanation.

In the notch cutting step S40, the cutting blade 38a and the holding table 14 are relatively moved along the X-axis direction (feeding direction), and the cutting blade 38a is cut into the notch 1d toward the center 1f of the wafer 1. At this time, the X-axis moving mechanism 12 is controlled so that the cutting blade 38a does not come into contact with the holding table 14. When the cutting blade 38a cuts into the notch 1d, the notch chamfered portion formed in the notch 1d is removed.

Here, the shape of the cutting edge of the cutting blade 38a used in the notch cutting step S40 is preferably a shape corresponding to the shape of the notch 1d. That is, it is preferable that the cutting blade 38b used in the outer peripheral chamfer removing step S20 and the cutting blade 38a used in the notch cutting step S40 have different cutting edge shapes.

When the notch cutting step S40 is performed before the outer peripheral chamfering portion removing step S20, it is not necessary for the cutting blade 38a to cut in the entire area of the notch 1d. That is, the cutting blade 38b is cut and removed in the outer peripheral chamfering portion removing step S20 from the portion of the notch 1d facing the outer peripheral 1c. Therefore, in the notch cutting step S40, the notch 1d may be cut into the cutting blade 38a at the portion not removed in the outer peripheral chamfering portion removing step S20.

In the wafer processing method according to the present embodiment, all the chamfered portions of the wafer 1 are removed by performing the outer peripheral chamfered portion removing step S20 and the notch cutting step S40. Then, in the wafer processing method according to the present embodiment, after performing the outer peripheral chamfering portion removing step S20 and the notch cutting step S40, the wafer 1 is carried out from the cutting device 2. After that, the back surface grinding step S50 is performed in which the wafer 1 is ground from the back surface 1b side to thin the wafer 1 to the finish thickness.

FIG. 6 is a perspective view schematically showing the back surface grinding step S50. The back surface grinding step S50 is performed by the grinding device 52. The grinding device 52 includes a spindle 54 that rotates in the vertical direction by a rotational drive source (not shown). A disk-shaped wheel mount 56 is fixed to the lower end of the spindle 54, and a grinding wheel 58 that rotates according to the rotation of the spindle 54 is mounted on the lower surface of the wheel mount 56. Grinding wheels 60 arranged in an annular shape are fixed to the lower surface of the grinding wheel 58.

Further, below the grinding wheel 58, a holding table 62 for holding the wafer 1 to be a workpiece is provided. The holding table 62 is configured in the same manner as the holding table 14 of the cutting device 2, and the upper surface of the holding table 62 is the holding surface 62a.

In the back surface grinding step S50, the wafer 1 is placed on the holding surface 62a with the back surface 1b side facing upward and the front surface 1a side facing the holding surface 62a, and the wafer 1 is sucked and held by the holding table 62. At this time, in order to protect the device 5 and the like formed on the surface 1a of the wafer 1, the surface protection tape 7 is previously attached to the surface 1a of the wafer 1. The surface protective tape 7 is a resin film having an adhesive layer on its surface, and has a diameter equivalent to that of the surface 1a of the wafer 1.

Next, the spindle 54 is rotated, the grinding wheel 58 is lowered, the grinding wheel 60 moving on the annular orbit is brought into contact with the wafer 1, the wafer 1 is ground from the back surface 1b side, and the wafer 1 is thinned to the finishing thickness. To become.

As described above, in the wafer 1 processing method according to the present embodiment, the chamfered portion is removed in advance at the outer peripheral 1c and the notch 1d of the wafer 1. Therefore, when the wafer 1 is ground from the back surface 1b side and thinned, a sharp knife edge shape is not formed at the end portion, so that the end portion of the thinned wafer 1 is less likely to be chipped or cracked. In particular, it is possible to prevent the wafer 1 from being chipped due to the remaining notch chamfered portion.

The present invention is not limited to the description of the above embodiment, and can be modified in various ways. For example, in the above embodiment, the holding step S30 is carried out in front of the notch cutting step S40 so that the cutting blade 38a does not hit the holding table 14, and the notch 1d protrudes outside the outer peripheral edge of the holding table 14. I let you. However, one aspect of the present invention is not limited to this.

For example, the holding table 14 of the cutting device 2 may be provided with an entry groove for the cutting blade 38a that cuts into the notch 1d of the wafer 1. Then, in the whole area holding step S10, when the center 1f of the wafer 1 and the center 14b of the holding surface 14a overlap, the orientation of the wafer 1 is adjusted so that the notch 1d of the wafer 1 overlaps the approach groove.

In this case, the notch cutting step S40 can be carried out before or after the outer peripheral chamfer removing step S20 without carrying out the protrusion holding step S30. In the notch cutting step S40, the holding table 14 is rotated in advance so that the center 14b of the holding surface 14a and the approach groove are aligned in the X-axis direction (feeding direction). Then, the cutting blade 38a cuts into the notch 1d from the X-axis direction, and the chamfered portion of the notch 1d is removed. At this time, since the cutting blade 38a enters the approach groove, it does not come into contact with the holding table 14.

However, the wafer 1 is not supported by the holding table 14 at the portion of the holding table 14 that overlaps with the approach groove. Therefore, in the outer peripheral chamfer removal step S20, in order to prevent the wafer 1 from being damaged when the cutting blade 38a cuts the portion of the wafer 1, it is necessary to take measures such as processing the wafer 1 under a processing condition with a small load. It should be noted that

Further, in the above embodiment, in the notch cutting step S40, a case where the cutting blade 38a cuts into the notch 1d from the X-axis direction (feeding direction) has been described, but one aspect of the present invention is not limited to this. That is, in one aspect of the present invention, the cutting blade 38a may cut into the notch 1d of the wafer 1 from another direction.

For example, in the protrusion holding step S30, the cutting blade 38a is positioned above the notch 1d of the wafer 1 protruding outside the holding table 14. More specifically, the tip of the cutting blade 38a in the X-axis direction is positioned slightly above the notch 1d of the wafer 1 on the inner side in the radial direction.

After that, in the notch cutting step S40, the Y-axis Z-axis moving mechanism 34 is operated to lower the rotating cutting blade 38a along the Z-axis direction, and the cutting blade 38a is cut into the notch 1d. Even in this case, since the notch chamfered portion is removed, the knife edge shape is not formed at the end portion of the wafer 1 after the back surface grinding step S50 is performed.

In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

1 Wafer 1a Front surface 1b Back surface 1c Outer circumference 1d Notch 1e End 1f Center 1g tangent line 3 Scheduled division line 5 Device 7 Surface protection tape 2 Cutting device 4 Base 4a, 4b, 4c Opening 6 Cassette mounting base 8 Cassette 12 X-axis movement mechanism 12a Table cover 12b Dust-proof and drip-proof cover 14 Holding table 14a Holding surface 14b Center 16 Guide rail 18 First support structure 20 Rail 22 Movement mechanism 24 Transport unit 26 Grip mechanism 32 Second support structure 34 Y-axis Z-axis movement mechanism 36a, 36b Cutting unit 38a, 38b Cutting blade 40 Imaging unit 42 Cleaning unit 44 Spinner table 46 Injection nozzle 48a, 48b Spindle housing 50a, 50b Spindle 52 Grinding device 54 Spindle 56 Wheel mount 58 Grinding wheel 60 Grinding grind 62 Holding table 62a Holding surface

Claims (3)

A wafer processing method for processing a wafer having a chamfered portion on the outer periphery, a notch formed on the outer peripheral edge, and a notch chamfered portion formed on the notch.
An entire area holding step of positioning the wafer on the holding surface so that the entire area of the wafer overlaps the holding surface of the holding table and holding the wafer on the holding table.
After the whole area holding step, an outer peripheral chamfer removing step of removing the chamfered portion of the outer peripheral surface from the surface of the wafer at a depth deeper than the finish thickness of the wafer.
Before or after the whole area holding step and the outer peripheral chamfer removing step, the wafer is positioned on the holding surface at a position where the notch protrudes outside the outer peripheral edge of the holding table, and the wafer is held by the holding table. Overhanging holding step and
After the protrusion holding step, a notch cutting step of cutting into the notch with a rotating cutting blade, and a notch cutting step.
After the outer peripheral chamfer removal step and the notch notch step, a protective tape is attached to the front surface of the wafer, and the wafer is ground from the back surface side to thin the wafer to the finish thickness. A method for processing a wafer, which comprises. The cutting blade and the holding table are relatively movable in the feed direction parallel to the holding surface of the holding table.
In the protrusion holding step, the wafer is positioned on the holding surface so that the center of the holding surface and the notch of the wafer are aligned along the feed direction.
The notch cutting step is characterized in that the cutting blade and the holding table are relatively moved along the feeding direction, and the cutting blade is cut into the notch toward the center of the wafer. The wafer processing method according to 1. The holding table internally comprises a first suction path leading to a first region of the holding surface and a second suction path leading to a second region of the holding surface.
In the whole area holding step, the wafer is sucked into the holding table through the first suction path and the second suction path.
Claim 1 or 2, wherein in the protrusion holding step, the wafer is sucked into the holding table through the first suction path and not into the holding table through the second suction path. The wafer processing method described in 1.

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