JP7765953B2 - Blade detection unit and cutting device equipped with same - Google Patents

Description

The present invention relates to a blade detection unit and a cutting device equipped with the same, and more specifically to a mechanism for protecting the blade detection unit.

Conventionally, cutting devices equipped with cutting blades for cutting semiconductor wafers have been known, as disclosed in Patent Documents 1 and 2, for example. The cutting blade wears as cutting occurs, causing the tip position of the cutting edge to change relative to the holding surface of the holding table. When the tip position of the cutting edge changes, the depth of cut into the workpiece also changes. For this reason, as disclosed in Patent Documents 1 and 2, it is known to detect the tip position of the cutting edge using a blade detection unit (cutting blade detection mechanism) and correct the depth of cut.

The blade detection unit disclosed in Patent Document 1 has a light-emitting unit including a light-emitting surface and a light-receiving unit including a light-receiving surface facing the light-emitting surface, and detects the lower end position (tip position) of the cutting blade's cutting edge relative to the holding surface of the holding table based on the height position of the cutting blade when light from the light-emitting surface is blocked by the cutting blade inserted between the light-emitting unit and the light-receiving unit.

As a result, if foreign matter such as cutting chips adheres to the light-emitting surface or light-receiving surface, there is a risk that the position of the bottom end of the cutting blade's cutting edge may be erroneously detected. Therefore, as disclosed in Patent Document 2, a configuration has been proposed in which a cover is provided to cover the light-emitting unit and light-receiving unit.

Japanese Patent Application Laid-Open No. 2001-298001 Japanese Patent Application Laid-Open No. 2003-211354

When cutting, cutting water is supplied to the cutting blade, but the cutting chips produced by the cutting process mix with the cutting water, creating contaminated water, which then turns into mist and floats in the air as the cutting blade rotates.

As a result, even if the blade detection unit is covered, there is a concern that mist may enter the cover through gaps and adhere to the light-emitting or light-receiving surface as foreign matter.

If foreign matter adheres to the light-emitting or light-receiving surface in this way, the accurate position of the bottom end of the cutting blade may not be detected, which could result in defective processing.

In light of the above issues, the present invention proposes a new technology that protects the blade detection unit and enables the accurate detection of the bottom end position of the cutting blade.

The above is the problem that this invention aims to solve, and next we will explain the means for solving this problem.

According to one aspect of the present invention, the blade detection unit has a light-emitting unit and a light-receiving unit that faces the light-emitting unit and receives light from the light-emitting unit, and detects the tip of the cutting blade when the cutting blade is positioned between the light-emitting unit and the light-receiving unit. The blade detection unit also has a protective member that is inserted between the light-emitting surface of the light-emitting unit and the light-receiving surface of the light-receiving unit and is in close contact with the light-emitting surface and the light-receiving surface, respectively, and a positioning unit that positions the protective member at a protective position where it is inserted between the light-emitting unit and the light-receiving unit, and at a retracted position retracted from the protective position.

Furthermore, according to one aspect of the present invention, the protective member is made of a material that is compressively deformable and can be cut by the cutting blade.

Furthermore, according to one aspect of the present invention, a cutting device is provided that includes a blade detection unit, a holding table that holds a workpiece, and a cutting unit that has a cutting blade that cuts the workpiece held by the holding table.

According to one aspect of the present invention, when the position of the cutting blade tip cannot be detected, the protective member is positioned in the protective position and comes into close contact with the light-emitting surface and the light-receiving surface, thereby preventing mist containing cutting debris from adhering to the light-emitting surface and the light-receiving surface as foreign matter.

Furthermore, even if, due to some obstacle, the protective member does not move to the retracted position but remains in the protective position, causing the cutting blade to descend, the cutting blade can still cut into the protective member, preventing damage to the cutting blade.

FIG. 10 is a diagram showing an example of a cutting device equipped with a blade detection unit. 1A is a diagram illustrating a state in which the protection mechanism is positioned at a retracted position, and FIG. 1B is a diagram illustrating a state in which the protection mechanism is positioned at a protection position. FIG. 1 is a schematic diagram of the blade detection unit seen from above.

An embodiment of the present invention will now be described with reference to the drawings.
FIG. 1 is a diagram showing an overview of a cutting device 1 equipped with a blade detection unit 20 according to the present invention.

As shown in FIG. 1, the cutting device 1 dices a plate-shaped workpiece W, such as a semiconductor wafer, using a cutting unit 5. The cutting device 1 is configured with a holding table 2, an imaging unit 3, a movement mechanism (Y-axis movement mechanism 41, Z-axis movement mechanism 42), the cutting unit 5, and a blade detection unit 20. The workpiece W may also be an optical device wafer, a plate-shaped inorganic material substrate, a plate-shaped ductile material, etc.

The holding table 2 is disk-shaped, with a horizontal holding surface formed on its upper surface. The holding surface is made of a porous material, and is connected to a suction source (not shown) to generate negative pressure, which causes the workpiece W to be sucked and held on the holding surface.

The holding table 2 is moved in the X-axis direction by an X-axis movement mechanism (not shown) provided within the base 6, and the workpiece W is fed for processing to the cutting unit 5.

Around the periphery of the holding table 2, multiple clamps 7 are provided to clamp the annular frame F to which the workpiece W is fixed. The workpiece W is fixed to the annular frame F via tape T and is handled as a wafer unit U.

The holding table 2 is surrounded by a cover plate 8, and a blade detection unit 20 is provided on the cover plate 8 to detect the lower end position of the cutting edge of the cutting blade of the cutting unit 5.

The cutting unit 5 comprises a spindle 52 driven by a motor (not shown) and a cutting blade 51 fixed to the tip of the spindle 52. The cutting blade 51 is, for example, a circular grinding stone in which abrasive grains made of synthetic diamond are held in place by a bond material.

The cutting unit 5 is moved in the Y-axis and Z-axis directions by a Y-axis movement mechanism 41 and a Z-axis movement mechanism 42. The Y-axis movement mechanism 41 supports the cutting unit 5 so that it can move relative to the base 6 in the Y-axis direction (corresponding to the indexing feed direction). The Z-axis movement mechanism 42 supports the cutting unit 5 so that it can move relative to the base 6 in the Z-axis direction (corresponding to the cutting feed direction).

The Y-axis movement mechanism 41 is composed of a pair of guide rails 41a, 41a attached to the front of the gantry column 9 and extending parallel to the Y-axis direction, a ball screw 41b positioned between the guide rails 41a, 41a, and a motor 41c fixed to one end of the ball screw 41b. The ball screw 41b is connected to the Y-axis movement plate 4Y via a nut (not shown), and by rotating the ball screw 41b with the motor 41, the Y-axis movement plate 4Y moves in the Y-axis direction along the guide rails 41a, 41a.

The Z-axis movement mechanism 42 is composed of a pair of guide rails 42a, 42a attached to the front surface of the Y-axis movement plate 4Y and extending parallel to the Z-axis direction, a ball screw 42b positioned between the guide rails 42a, 42a, and a motor 42c fixed to one end of the ball screw 42b. The ball screw 42b is connected to the Z-axis movement plate 4Z via a nut (not shown), and by rotating the ball screw 42b with the motor 42, the Z-axis movement plate 4Z moves in the Z-axis direction along the guide rails 42a. The imaging unit 3 and cutting unit 5 are fixed to the lower end of the Z-axis movement plate 4Z.

The imaging unit 3 captures an image of the planned dividing line (street) of the workpiece W before cutting in order to align the cutting unit 5 with the street. The imaging unit 3 is, for example, a camera using a CCD (Charge Coupled Device) image sensor.

Next, we will explain the blade detection unit 20 shown in Figures 2(A) and (B). The blade detection unit 20 is also called a setup sensor, and detects the bottom end position of the cutting edge of the cutting blade 51, i.e., the Z-direction position, at a predetermined timing or at any timing when necessary, and adjusts and sets up the cutting height position in response to wear on the cutting blade 51.

The blade detection unit 20 has a rectangular parallelepiped detection base 21. A roughly L-shaped optical sensor 22 having a vertical wall portion 22z and a horizontal plate portion 22h is fixed to the top surface of the detection base 21.

A blade insertion groove 22a that penetrates in the X-axis direction is formed in the vertical wall portion 22z of the optical sensor 22. The light-emitting surface 23a of the light-emitting unit 23 and the light-receiving surface 24a of the light-receiving unit 24 are arranged on the opposing surfaces of the wall portions 22b on both sides of the blade insertion groove 22a, and light emitted from the light-emitting unit 23 is detected by the light-receiving unit 24.

Nozzles 25, 26 are provided on the horizontal plate portion 22h of the optical sensor 22 to supply air or cleaning liquid such as pure water to the light-emitting surface 23a of the light-emitting unit 23 and the light-receiving surface 24a of the light-receiving unit 24. This allows cleaning liquid to be supplied from the nozzles 25, 26 at a predetermined timing, followed by air blowing, thereby removing foreign matter adhering to the light-emitting surface 23a and the light-receiving surface 24a and improving the accuracy of cutting blade detection.

A protection mechanism 30 is provided on one side of the detection table 21 in the X-axis direction, which is movable in the X-axis direction relative to the detection table 21. The protection mechanism 30 is connected to the detection table 21 via two rods 31, and moves in the X-axis direction by advancing and retracting the rods 31 using a positioning unit 27 provided within the detection table 21. The positioning unit 27 is composed of a direct-acting air cylinder or electromagnetic actuator that moves the rods 31 forward and backward. This makes it possible to achieve a configuration that is less prone to malfunctions and failures, compared to, for example, a configuration in which the detection table 21 is protected by driving a rotating cover.

Figure 2(A) shows the state in which the protection mechanism 30 has been moved to the retracted position when detecting the cutting blade 51. Figure 2(B) shows the state in which the protection mechanism 30 has been moved to the protection position when not detecting the cutting blade 51. In this way, the protection mechanism 30 moves between the retracted position and the protection position.

The protection mechanism 30 has a rectangular parallelepiped main body 30a, and a protection member 32 protrudes from the main body 30a toward the detection base 21. When the protection mechanism 30 is in the protection position, the protection member 32 is inserted between the light-emitting surface 23a and the light-receiving surface 24a in the blade insertion groove 22a.

The protective member 32 is made of a material that can be compressed and deformed and cut by the cutting blade 51, and can be made of, for example, sponge, rubber, urethane, or other resin materials.

Also, as shown in Figure 3, the protective member 32 has a width 32w that is slightly wider than the groove width 22w (width in the Y-axis direction) of the blade insertion groove 22a, so that it is inserted between the light-emitting surface 23a and the light-receiving surface 24a in a slightly compressed state.

When the protective member 32 is inserted into the blade insertion groove 22a in a compressed state, the sides of the protective member 32 come into close contact with the light-emitting surface 23a and the light-receiving surface 24a, protecting the light-emitting surface 23a and the light-receiving surface 24a. This prevents cutting fluid supplied to the cutting blade 51, cutting chips generated by cutting, and even mist containing cutting chips from adhering to the light-emitting surface 23a and the light-receiving surface 24a as foreign matter during cutting.

Furthermore, as shown in Figure 3, when the protective member 32 is inserted into or removed from the blade insertion groove 22a, the light-emitting surface 23a and the light-receiving surface 24a can be cleaned by wiping them with the side surfaces 32a, 32a on both sides of the protective member 32.

Also, as shown in Figures 2(A) and 2(B), an attachment groove 30b that opens upward is formed in the upper part of the main body 30a of the protection mechanism 30, and the rear end of the protection member 32 is inserted into the attachment groove 30b, thereby fixing the protection member 32 to the main body 30a. The tip side of the protection member 32 protrudes from the main body 30a and is inserted into the blade insertion groove 22a.

Here, the mounting groove 30b formed in the main body 30a of the protection mechanism 30 is positioned on an extension of the blade insertion groove 22a in the X-axis direction and is provided so as to penetrate in the X-axis direction. As a result, only the protection member 32 is exposed upward on an extension of the blade insertion groove 22a in the X-axis direction.

With the above configuration, as shown in Figure 2 (B), when the position of the cutting edge of the cutting blade 51 is not being detected, the protection mechanism 30 is positioned in the protection position, and the protection member 32 is inserted into the blade insertion groove 22a to protect the light-emitting surface 23a and the light-receiving surface 24a, preventing mist containing cutting debris from adhering to the light-emitting surface 23a and the light-receiving surface 24a as foreign matter. In addition, when the protection member 32 moves, the light-emitting surface 23a and the light-receiving surface 24a are cleaned. In this way, the bottom end position (height position) of the cutting blade 51 can be detected with high accuracy.

On the other hand, as shown in FIG. 2(A), when detecting the position of the cutting edge of the cutting blade 51, the protective member 32 of the protection mechanism 30 is moved away from the blade insertion groove 22a to a retracted position, thereby opening the blade insertion groove 22a. The cutting blade 51 is then lowered and inserted into the blade insertion groove 22a. When the cutting edge of the cutting blade 51 is positioned between the light-emitting element 23 and the light-receiving element 24 and the light emitted from the light-emitting element 23 is blocked by the cutting blade 51, the amount of light received by the light-receiving element 24 changes. By detecting this change, the lower end position (height position) of the cutting edge of the cutting blade 51 is detected.

Here, for example, as shown in Figure 2(B), even if, due to some obstacle, the protection mechanism 30 is positioned in the protection position instead of moving to the retracted position, causing the cutting blade 51 to descend, the protection member 32 will be present in the blade insertion groove 22a, allowing the cutting blade 51 to cut into the protection member 32.

This prevents damage to the cutting blade 51. If the cutting blade 51 were to be damaged, it would be necessary to regenerate the cutting edge of the cutting blade 51 by dressing or pre-cutting, or if the blade is damaged to the point where it cannot be regenerated, it would be necessary to replace the blade, and these would involve a lot of additional work, such as the associated resetting work. However, this embodiment prevents these problems.

Furthermore, in the protective mechanism 30, the protective member 32 exists on the extension line of the blade insertion groove 22a in the X-axis direction. Therefore, even if the cutting blade 51 cuts into the main body 30a side of the protective mechanism 30, the cutting blade 51 will cut into the protective member 32. This prevents damage to the cutting blade 51.

DESCRIPTION OF SYMBOLS 1 Cutting device 2 Holding table 3 Imaging unit 5 Cutting unit 6 Base 7 Clamp 8 Cover plate 20 Blade detection unit 21 Detection table 22 Optical sensor 22a Blade insertion groove 22b Wall portion 22h Horizontal plate portion 22z Vertical wall portion 23 Light emitting portion 23a Light emitting surface 24 Light receiving portion 24a Light receiving surface 25 Nozzle 26 Nozzle 27 Positioning unit 30 Protection mechanism 30a Main body portion 30b Mounting groove 31 Rod 32 Protection member 32w Width 41 Y-axis movement mechanism 42 Z-axis movement mechanism 51 Cutting blade F Annular frame T Tape U Wafer unit W Work

Claims (3)

A blade detection unit having a light emitting unit and a light receiving unit facing the light emitting unit and receiving light from the light emitting unit, wherein the blade is positioned between the light emitting unit and the light receiving unit to detect the tip of the cutting blade,
a protective member inserted between the light-emitting surface of the light-emitting unit and the light-receiving surface of the light-receiving unit and brought into close contact with the light-emitting surface and the light-receiving surface, respectively;
a main body to which the protection member is fixed;
a positioning unit that moves the main body in a horizontal direction to position the protection member at a protection position where the protection member is inserted between the light-emitting unit and the light -receiving unit, and at a retracted position where the protection member is retracted from the protection position;
a detection base that houses the positioning unit and the light emitting unit;
a rod that protrudes from the detection table, connects the positioning unit and the main body, and moves forward and backward by the positioning unit;
having
Blade detection unit. The protective member is made of a material that is compressively deformable and can be cut by the cutting blade.
2. The blade detection unit according to claim 1. The blade detection unit according to claim 1 or 2;
a holding table for holding the workpiece;
a cutting unit having a cutting blade for cutting the workpiece held by the holding table;
A cutting device comprising: