JP2002151444A - Precutting method using cutting blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precutting method using a cutting blade with which adaptation of an object to be processed and the cutting blade can be made favorable in a short time. SOLUTION: In this precutting method using a cutting blade, a dummy member held on a chuck table holding an object to be processed is cut by a cutting blade formed by connecting abrasive grains by metal plating. Cutting is performed while a positive voltage is applied to the cutting blade, and a conductive cutting liquid supplied to the dummy member held on the chuck table is charged to a negative voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting blade for cutting a workpiece such as a semiconductor wafer, and more particularly to a cutting blade formed in a circular shape by bonding abrasive grains made of diamond or the like by metal plating such as nickel. Precut method.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process,
Circuits such as ICs and LSIs are formed in a large number of regions arranged in a grid on the surface of a semiconductor wafer having a substantially disk shape, and each region where the circuits are formed is formed along a cutting line called a predetermined street. Individual semiconductor chips are manufactured by dicing. The semiconductor chips divided in this way are packaged and widely used for electric devices such as mobile phones and personal computers.

[0003] A dicing apparatus for dicing a semiconductor wafer along a cutting line moves a circular cutting blade mounted on a rotary spindle at about 30,000 rpm while relatively moving along the cutting line.
The semiconductor wafer is cut as required. As a cutting blade used in such a dicing apparatus, a so-called electroformed blade in which abrasive grains made of diamond or the like are formed in a circular shape by bonding with metal plating such as nickel is generally used. Because this electroformed blade has a high holding power of the abrasive grains, if the familiarity with a workpiece such as a semiconductor wafer is poor,
Relatively large chips are formed on both sides of the cutting groove formed by cutting, which causes deterioration of the quality of the semiconductor chip. Therefore, when using a new electroformed blade in a manufactured state, a precut is generally performed to cut a dummy member formed of substantially the same material as the workpiece before cutting the workpiece. I do.

[0004]

However, the above-mentioned precut needs to be cut by a total of about 40 to 80 m in order to improve the familiarity between the workpiece and the electroformed blade.
In general, the pre-cut is performed by gradually increasing the processing speed from an extremely low processing speed to a processing speed of cutting a workpiece in a process of cutting about 40 to 80 m.
It takes about 0 to 60 minutes. Therefore, the precut is a factor that alienates the improvement of the production efficiency of the dicing operation, and a major technical problem is how to reduce the precut time. On the other hand, when a user who does not have a dummy member purchases an electroformed blade that has not been precut, the same operation as precut must be performed at the expense of a workpiece such as a semiconductor wafer to be a product. As a result, defective products are produced, yield is poor, and productivity is remarkably reduced.

The present invention has been made in view of the above-mentioned facts, and a main technical problem of the present invention is to provide a method for precutting a cutting blade which can improve the familiarity between the workpiece and the cutting blade in a short time. It is in.

[0006]

According to the present invention, a dummy member held on a chuck table for holding a workpiece is formed by bonding abrasive grains by metal plating. A pre-cutting method of a cutting blade for cutting with a cutting blade, wherein a positive voltage is applied to the cutting blade, and a conductive cutting fluid supplied to the dummy member held on the chuck table is charged to a negative voltage. A method for precutting a cutting blade to be cut is provided.

The cutting blade is formed by bonding diamond abrasive grains by nickel plating. In the pre-cut, when the rotation speed of the cutting blade is 10
000-40000 rpm, cutting feed rate 10-80
mm / sec, depth of cut: 0.1-0.3 mm, applied voltage: 100-200 V, DC voltage of 1 M pulse / sec, cutting fluid electric resistance: 4000-10000 Ω · cm. You.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for precutting a cutting blade according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a dicing device as a cutting device for performing a precut method of a cutting blade according to the present invention. The dicing apparatus in the illustrated embodiment has a substantially rectangular parallelepiped device housing 2.
Is provided. In the apparatus housing 2, a chuck table 3 for holding a workpiece is provided so as to be movable in a cutting feed direction indicated by an arrow X. The chuck table 3 includes a suction chuck support 31 and a suction chuck 32 mounted on the suction chuck support 31, and is a workpiece on a mounting surface, which is a surface of the suction chuck 32. For example, a disk-shaped semiconductor plate is held by suction means (not shown). The chuck table 3 is configured to be rotatable by a rotation mechanism (not shown).

The dicing apparatus in the illustrated embodiment has a spindle unit 4 as cutting means. The spindle unit 4 is mounted on a moving base (not shown) and adjusted to move in a direction indicated by an arrow Y which is an indexing direction and a direction indicated by an arrow Z which is a cutting direction.
The rotary spindle 42 includes a rotary spindle 42 rotatably supported by a rotary drive mechanism (not shown) and a cutting blade 43 mounted on the rotary spindle 42. As the cutting blade 43, a hub type cutting blade 43a shown in FIG. 2 and a washer type cutting blade 43b shown in FIG. 3 can be used. The hub-type cutting blade 43a shown in FIG. 2 is formed by electrodepositing, for example, about 10 μm diamond abrasive grains on the outer periphery of one side surface of a circular hub 431 formed of aluminum and one side of the circular hub 431. Blade section 432. In addition, in order to form the blade portion 432 on the outer peripheral portion on one side surface of the hub 431, a normal electroplating method can be used. That is, for example, by mixing diamond abrasive grains in a nickel sulfate solution contained in a plating tank, and nickel plating the outer periphery of one side of the hub base in a plating solution in which diamond abrasive grains are mixed in the nickel sulfate solution, An electrodeposited abrasive layer made of a composite plating layer formed by bonding diamond abrasive grains by nickel plating is formed. Thereafter, by etching and dissolving the outer peripheral portion of the hub base, a blade portion 432 made of a composite plating layer in which diamond abrasive grains protruding outward from the outer periphery of the hub 431 are combined by nickel plating is formed. Further, in order to manufacture the washer-type cutting blade 43b shown in FIG. 3, diamond abrasive grains were bonded to the outer periphery of one side of a circular base made of aluminum by nickel plating by the above-described electrodeposition method. After forming the electrodeposited abrasive layer composed of the composite plating layer, the base is etched and dissolved. Cutting fluid supply nozzles 44 for supplying a cutting fluid are provided on both sides of the above-described cutting blade 43.

The dicing apparatus according to the illustrated embodiment has a suction chuck 3 constituting the chuck table 3.
The imaging of the surface of the workpiece held on the surface of No. 2 detects the region to be cut by the cutting blade 43,
An imaging mechanism 5 for checking the state of the cutting groove is provided. The imaging mechanism 5 is composed of optical means such as a microscope and a CCD camera. Further, the dicing device includes a display unit 6 for displaying an image captured by the imaging mechanism 5.
Is provided.

The dicing apparatus in the illustrated embodiment has a cassette 7 for stocking a semiconductor wafer 8 as a workpiece. The semiconductor wafer 8 is supported by a tape 10 on an annular support frame 9 formed of a metal material such as stainless steel, and is accommodated in the cassette 7 while being supported by the support frame 9. The cassette 7 is placed on a cassette table 71 that is vertically movable by an elevating means (not shown).

The dicing apparatus in the illustrated embodiment unloads a semiconductor wafer 8 (a state supported by a tape 10 on a support frame 9) as a workpiece housed in a cassette 7 to a workpiece mounting area 11. Workpiece unloading means 12; Workpiece transfer means 13 for transferring the semiconductor wafer 8 unloaded by the workload unloading means 12 onto the chuck table 3;
The cleaning unit 14 includes a cleaning unit 14 for cleaning the semiconductor wafer 8 cut by the above-described process, and a cleaning / conveying unit 15 for conveying the semiconductor wafer 8 cut by the chuck table 3 to the cleaning unit 14.

Next, the processing operation of the above dicing apparatus will be briefly described. The semiconductor wafer 8 supported by the support frame 9 accommodated in a predetermined position of the cassette 7 via the tape 10 (hereinafter, the semiconductor wafer 8 supported by the support frame 9 by the tape 10)
The semiconductor wafer 8 is positioned at the carry-out position when the cassette table 71 is moved up and down by a lifting means (not shown). Next, the workpiece unloading means 12 moves forward and backward, and unloads the semiconductor wafer 8 positioned at the unloading position to the workpiece mounting area 11. The semiconductor wafer 8 carried out to the workpiece mounting area 11 is transported to the mounting surface of the suction chuck 32 constituting the chuck table 3 by the turning operation of the workpiece transporting means 13,
The suction chuck 3 is operated by a suction operation of a suction means (not shown).
2 is held by suction. Thus, the semiconductor wafer 8
Is sucked and held, and is moved to a position immediately below the imaging mechanism 5. When the chuck table 3 is positioned directly below the image pickup mechanism 5, the image pickup mechanism 5 detects a cutting line formed on the semiconductor wafer 8, and the arrow Y that is the indexing direction of the spindle unit 4.
The precision alignment work is performed by adjusting the movement in the direction.

Thereafter, while the cutting blade 43 is cut in a predetermined amount by the method shown by the arrow Z and is rotated in a predetermined direction, cutting water is supplied from a cutting liquid supply nozzle 44 to suck and hold the semiconductor wafer 8. The semiconductor wafer 8 held on the chuck table 3 is moved by the cutting blade 43 at a predetermined cutting feed speed in a direction indicated by an arrow X which is a cutting feed direction (a direction orthogonal to the rotation axis of the cutting blade 43). It is cut along a predetermined cutting line (street). That is, the cutting blade 43 is mounted on the spindle unit 4 which is moved and adjusted in the direction indicated by the arrow Y which is the indexing direction and the direction indicated by the arrow Z which is the cutting direction, and is rotationally driven. Is moved along the lower side of the cutting blade 43 in the cutting feed direction, so that the semiconductor wafer 8 held on the chuck table 3 is moved.
Is cut along a predetermined cutting line by the cutting blade 43. When the semiconductor wafer 8 is cut along the cutting line, the semiconductor wafer 8 is divided into individual semiconductor chips. The divided semiconductor chips do not fall apart by the action of the tape 10, and the state of the semiconductor wafer 8 supported by the frame 9 is maintained. After the cutting of the semiconductor wafer 8 is completed in this manner, the chuck table 3 holding the semiconductor wafer 8 is first returned to the position where the semiconductor wafer 8 is suctioned and held, and the suction action of the suction means (not shown) is cut off here. Then, the suction holding of the semiconductor wafer 8 is released. Next, the semiconductor wafer 8 is transported to the cleaning means 14 by the cleaning and transporting means 15, where it is cleaned. The semiconductor wafer 8 thus cleaned is carried out to the work placement area 11 by the work transfer means 13. Then, the semiconductor wafer 8 is placed on the workpiece unloading means 1.
The cassette 2 is stored in a predetermined position of the cassette 7.

Next, a method for pre-cutting a new cutting blade 43 using the above-mentioned dicing apparatus will be described.
This will be described with reference to FIG. First, the dummy member 50 is attached to the tape 10 mounted on the support frame 9. The dummy member 50 is formed of silicon (Si), which is substantially the same material as the material forming the semiconductor wafer 8. In this manner, the dummy member 50 supported by the support frame 9 is placed on the chuck table 3 and held by suction. Then, as described above, the cutting fluid supply nozzle 4
4 supplies the cutting fluid to the dummy member 50 on the chuck table 3 and sets the cutting blade 43 to 10,000 to 40,000.
While rotating at rpn, the chuck table 3 is moved at a cutting speed of 10 to 80 mm / sec in a direction indicated by an arrow X, which is a cutting feed direction, to perform a precut of a new cutting blade 43. It is desirable that the depth of cut when performing the precut is 0.1 to 0.3 mm.

On the other hand, there is provided an electrolytic power source 60 for applying a positive voltage to the cutting blade 43 and charging the conductive cutting fluid supplied to the dummy member 50 held on the chuck table 3 to a negative voltage. Positive electrode 61 of electrolytic power supply 60
Is connected via a brush 65 to a rotating spindle 42 equipped with a cutting blade 43, and the negative electrode 62 is connected to the support frame 9.
Connect to Note that the rotary spindle 42 and the spindle housing 41 are air-bearing and are electrically insulated from each other. Then, when the above-described precut is performed, the distance between the positive electrode 61 and the negative electrode 62 of the electrolytic power source 60 is
A DC voltage of 1 M (mega) pulse (1 M pulse / second) is applied at 0 to 200 V per second. At this time, as the cutting fluid supplied from the cutting fluid supply nozzle 44 to the dummy member 50, a conductive cutting fluid having an electric resistance of 4000 to 10000 Ω · cm, for example, city water is used. Therefore, the brush 65, the rotating spindle 42, the cutting blade 4
3. Electrolytic current flows through the conductive cutting fluid and the support frame 9. As a result, the bond portion made of a metal such as nickel that binds the diamond abrasive grains of the cutting blade 43 is electrolyzed and eluted to improve the protrusion of the abrasive grains, and appropriate pores are formed on the outer peripheral portion of the cutting blade. It is formed. As a result, the cutting performance of the cutting blade is improved and the initial wear is promoted, so that the dummy member 50, that is, the workpiece and the cutting blade can be made familiar with a short precut. According to the precut method described above, a precut that is equivalent to the conventional precut can be performed with a cutting total length of 1 to 2 m, and the time required for the precut can be reduced to several tenths.

Although the precut method according to the present invention has been described based on the illustrated embodiment, the present invention is not limited to the embodiment. For example, in the illustrated embodiment, the negative electrode 62 of the electrolytic power source 60 is connected to the dummy member 50.
Although the example in which the negative electrode 62 is connected to the support frame 9 for supporting the negative electrode 62 may be connected to the chuck table 3, or the negative electrode 62 is attached to the cutting liquid supply nozzle 44 and the negative electrode 62 is attached to the negative electrode 62. You may connect. When a user who does not have a dummy member purchases a cutting blade that has not been precut and performs precut at the expense of a workpiece such as a semiconductor wafer, the cutting total length of the precut according to the precut method described above is used. Is reduced, the number of defective products is reduced to one-tenth of the conventional value, and the yield can be improved.

[0019]

The pre-cutting method for a cutting blade according to the present invention is configured as described above, and has the following effects.

That is, according to the present invention, a positive voltage is applied to the cutting blade, and the cutting is performed while charging the conductive cutting fluid supplied to the dummy member held on the chuck table to a negative voltage. Electrolytic current flows through the cutting fluid. As a result, the bond portion made of metal binding the abrasive grains of the cutting blade is electrolyzed and eluted, and the protrusion of the abrasive grains is improved. As a result, the machinability of the cutting blade is improved, so that the pre-cut time can be shortened to several tenths of the conventional one, and the productivity can be improved. As described above, according to the precut method according to the present invention, the precut of the cutting blade can be performed in an extremely short time, so that the manufacturer of the cutting blade can easily ship after performing the precut.

[Brief description of the drawings]

FIG. 1 is a perspective view of a dicing device as a cutting device for performing a cutting blade precut method according to the present invention.

FIG. 2 is a perspective view showing one embodiment of a cutting blade for performing a precut method according to the present invention.

FIG. 3 is a perspective view showing another embodiment of a cutting blade for performing a precut method according to the present invention.

FIG. 4 is an essential part perspective view showing a precut state by a precut method according to the present invention.

[Explanation of symbols]

 2: Device housing 3: Chuck table 31: Suction chuck support 32: Suction chuck 4: Spindle unit 41: Spindle housing 42: Rotating spindle 43: Cutting blade 44: Cutting fluid supply nozzle 5: Imaging mechanism 6: Display means 7: Cassette 71: Cassette table 8: Semiconductor wafer 9: Support frame 10: Tape 11: Workpiece mounting area 12: Workpiece unloading means 13: Workpiece transfer means 14: Cleaning means 15: Cleaning transfer means 20: Dummy Member 60: electrolytic power supply

Claims (3)

[Claims] 1. A pre-cutting method of a cutting blade for cutting a dummy member held on a chuck table holding a workpiece by a cutting blade formed by bonding abrasive grains by metal plating. A pre-cutting method for a cutting blade, comprising: applying a positive voltage and cutting while charging a conductive cutting fluid supplied to the dummy member held on the chuck table to a negative voltage. 2. The pre-cutting method for a cutting blade according to claim 1, wherein the cutting blade is formed by bonding diamond abrasive grains by nickel plating. 3. The pre-cut has a rotation speed of the cutting blade of 10,000 to 40,000 rpm, a cutting feed speed of 10 to 80 mm / sec, and a cutting depth of 0.1 to 0.3 m.
m, DC voltage of 1 M pulse / sec at applied voltage of 100 to 200 V, electric resistance of the cutting fluid is 4000 to 10000Ω
3. The method for pre-cutting a cutting blade according to claim 1, wherein the method is performed under a condition of cm.