JPH10337725A - Method for cutting hard brittle material and semiconductor silicon wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high strength and smoothness simultaneously with cutting by again bringing a cutting means into contact with a cut surface once cut of a hard brittle material, and smoothening a cutter blade pattern of projections and recesses on the cut surface. SOLUTION: An ingot 1 to be cut is fixed to a fixed stand 2 by wax, and then a horizontal support plate 6 is moved down to a predetermined position immediately before the ingot 1 is brought into contact with a wire 12. Here, a radius of the ingot 1 to be cut 13 inputted, a wire driving motor 11 is driven so that its moving speed is set to constant, tension is set constantly, and a designating angle of an oscillation is designated to an oscillating rotary encoder 5 to control the oscillation. And, the plate 6 is moved down by using a vertically moving rotary encoder 9, and cutting is started. The wire 12 is again disposed at a cut surface having a cutting blade pattern as already cut by oscillating, protrusions of the blade pattern of projections and recesses on the cut surface are polished to remarkably reduce the projections and recesses of the wafer surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting method for cutting hard and brittle materials such as silicon, quartz, glass and ceramics for semiconductors, and more particularly to a cutting method for cutting ingots and the like of these hard and brittle materials and a hard and brittle material obtained by the cutting method. About the disk.

[0002]

2. Description of the Related Art Conventionally, as a cutting method for cutting hard and brittle materials such as silicon, quartz, glass, and ceramics for semiconductors, particularly ingots of these hard and brittle materials, a polishing blade is mainly provided on a disk-shaped inner periphery. The inner peripheral blade provided is rotated at high speed to cut the hard and brittle material by using the inner peripheral blade slicer. A method using a multi-wire saw for cutting while pressing against the wire is used.

[0003] In the above-mentioned double cutting method, in the multi-wire saw method, a hard brittle material ingot is pressed against a wire stretched in a large number of moving rows to cut the wire. As shown in FIG. 2, since parallel cutting blade patterns are formed in parallel, the cleavage surface of the hard and brittle material to be cut is easily aligned with the direction of the blade pattern because these blade patterns are linear. Therefore, the hard and brittle material is easily broken along the edge pattern.

[0004] Further, in the inner peripheral blade slicer system, the lower end of the ingot made of hard and brittle material is cut by an inner peripheral blade having a diameter larger than the diameter of the ingot.
As shown in (b), since the cut ripple has a curvature that matches the curvature of the inner peripheral edge, the cleavage plane of the hard and brittle material to be cut rarely coincides with the direction of the ripple, and the mulch It has higher strength than hard and brittle material discs by the wire saw method.

However, in recent years, high integration of semiconductors,
With the demand for larger devices and lower cost of devices such as liquid crystal, disk-shaped disks (wafers) made of hard and brittle materials such as silicon, quartz, glass, and ceramics for semiconductors used in these semiconductors and electronic components, etc. Wafers and the like cut from the hard and brittle material due to these enlargements have been rapidly growing, and in the polishing and the like at the time of cutting and at the time of handling and transporting such as taking out and the like and at the subsequent process,
The problem of insufficient strength that the material is easily crushed along the edge pattern, which is an uneven line of the cut surface, has become remarkable.

Further, the above-mentioned blade pattern on the cut surface is an irregular line on the surface, and these irregularities are removed by polishing, which is a post-process, and are mirror-finished by lapping, particularly in semiconductor silicon or the like. It is known that the strength of a wafer is improved.

However, with the recent demand for cost reduction, attempts have been made to directly perform lapping without the polishing step. Problems such as crushing or warping of the hard and brittle material disk due to insufficient strength may be caused by high pressure in processing.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a hard and brittle material disk (especially a semiconductor silicon wafer) having a smoothness enough to have sufficient strength even at the time of cutting, and to provide such a hard and brittle material disk. An object of the present invention is to provide a method for cutting a disk.

[0009]

In order to solve the above-mentioned problems, a method for cutting a hard and brittle material according to the present invention comprises the steps of: It is characterized by smoothing a blade pattern which is an unevenness on a surface. According to this feature, the unevenness of the blade pattern is averaged by the cutting means abutting again on the convex part of the blade pattern formed by cutting, thereby cutting the hard and brittle material disk having both high strength and smoothness. Can be obtained at the same time.

In the method for cutting a hard and brittle material according to the present invention, it is preferable that the cutting means is a wire saw, and the cutting is performed while giving relative swing between the hard and brittle material and the wire. With this configuration, the wire and the hard and brittle material to be cut are relatively rocked on the cut surface on which the blade pattern is formed, so that the wire repeatedly crosses the convex portion on the cut surface on which the blade pattern is formed ( In the case of using free abrasive grains, the abrasive grains are interposed between the wire and the blade pattern convex part), and the convex part is polished, and this polishing action averages the unevenness of the cut surface, so that the smoothness is high. It becomes a cut surface.

In the cutting method for a hard and brittle material according to the present invention, the swing is a pendulum swing, and a swing angle formed with a swing center has a substantially maximum value at which the hard and brittle material always contacts a wire. Is preferably controlled. By doing so, the time during which the hard and brittle material ingot, which is the object to be cut, is not separated from the wire and is not processed can be effectively reduced, and the cutting can be performed efficiently.

In the method for cutting a hard and brittle material according to the present invention, it is preferable that the swing angle is variably controlled at any time based on a cutting distance. In this way, the swing angle at which the hard and brittle material always contacts the wire can be easily obtained by calculation, by simply detecting only the cut distance, and the swing angle can be controlled. It can be implemented simply and accurately.

[0013] In the method for cutting hard and brittle material according to the present invention, the cutting means has an inner peripheral blade slicer for cutting the hard and brittle material by bringing the hard and brittle material into contact with the polishing blade. It is preferable to perform cutting while giving a relative movement between the hard brittle material and the inner peripheral blade slicer in a predetermined relative angle direction with respect to a cutting progress direction on a cutting plane. In this way, the polishing blade repeatedly comes into contact with the convex portion of the blade pattern formed by cutting at an angle different from the blade pattern, and the convex portion of the blade pattern is polished and averaged. Therefore, a cut surface having high smoothness can be obtained.

The semiconductor silicon wafer of the present invention is a semiconductor silicon wafer cut out from an ingot by a cutting means, and is characterized in that a cut surface thereof has a large number of crossing cutting edges. Since the semiconductor silicon wafer having this feature has high smoothness and high strength with the unevenness of the blade pattern at the time of cutting being averaged, not only the damage at the time of moving to the next process is small, but also the polishing process can be shortened, If necessary, the polishing process can be omitted.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) As shown in FIG. 1, an apparatus for performing the method for cutting hard and brittle material of the present invention has almost the same mechanism as a conventional wire saw apparatus.
As a mechanism for swinging, an ingot 1 which is a hard and brittle material to be cut is fixed to a fixed stand 2 using wax or the like, and a swing table 3 having the fixed stand 2 is attached to a swing shaft 4. A swing rotary encoder 5 connected to the swing shaft for swinging to the center is provided.

The swing rotary encoder 5 for swinging is fixed to a horizontal support plate 6 connected to a vertically moving slide table 7, and the horizontal support plate 6 is vertically moved by a vertical movement rotary encoder 9. By doing so, the ingot 1 fixed to the fixed stand 2 of the swing base 3 is moved downward, and the cutting wire 12 is moved.
, So that cutting can be performed.

The wire 12 is driven by a guide roll 10 which is rotated by a wire drive motor 11 and a drive belt 13, and the wire reciprocates at a constant speed between two reels around which the wire is wound. It has been like that.

The tension of the wire 12 is made constant by a dancer mechanism (not shown) for controlling the tension and the like. ).

In the first embodiment, the rotary encoder 5 for swinging and the rotary encoder 9 for vertical movement are controlled by a control computer (not shown).

The cutting operation of the method for cutting hard and brittle material according to the first embodiment will be described below. An operator fixes the ingot 1 to be cut to the fixing stand 2 using wax or the like, and then fixes the horizontal support plate 6. Is instructed from the control computer to lower the ingot 1 to a predetermined position immediately before the ingot 1 is brought into contact with the wire.

At this stage, when the operator inputs the radius R of the ingot 1 to be cut and presses the cutting start button of the control computer, the control computer displays the angle information of the swing rotary encoder 5 at that time. After resetting the position information of the rotary encoder 9 for vertical movement and driving the wire drive motor 11 to keep the moving speed constant, and adjusting the dancer mechanism to keep the tension constant,
The swing is controlled by instructing the swing rotary encoder 5 to instruct the swing angle, and the horizontal support plate 6 is lowered using the vertical movement rotary encoder 9 to start cutting.

The method of controlling the swing angle used in the first embodiment will be described with reference to FIG. 3A. In the first embodiment, as shown in FIG. , The swing angle θ is obtained by calculation at any time and is continuously changed.

The method of calculating the swing angle θ is as follows: the cutting distance is M, the radius of the ingot 1 to be cut is R, the distance from the center of swing to the center of the ingot 1 is L, and the ingot 1 is rotated. Is the maximum swing angle θ without leaving the wire.

(Equation 1) Can be determined by:

In this case, the swing angle θ is small at the start of cutting and at the end of cutting as shown in FIG. 3 (b), and the angle formed by two straight lines contacting the center of the swing with the outer periphery of the ingot 1 becomes the maximum value.

The cut surface of the ingot 1 cut in the first embodiment is a conventional wire saw or an inner peripheral slicer, but the cut portion of the ingot 1 is formed by the ingot 1 and the wire 12 in the present invention. Since there is only the vicinity of the bottom dead center of the swing center that comes into contact, the edge pattern generated on the cross section is shown in FIG.
As shown in the figure, the blade has a continuous non-uniform curvature without being parallel, and since the blade pattern has a predetermined curvature, the strength of the hard and brittle material disk obtained as compared with the conventional wire saw method Is improved.

FIG. 5 schematically shows the positional relationship between the wire 12 and the ingot 1 at the time of cutting according to the first embodiment, as shown in FIG. 5. The wire 12 is already cut by swinging and has a blade pattern. In this case, since the loose abrasive grains are interposed between the wire 12 and the cutting surface 1 ′, the projections of the blade pattern, which are irregularities on the cutting surface, are polished. As a result, the unevenness of the surface of the wafer obtained by cutting can be significantly reduced, and as a result, a wafer having extremely high strength can be obtained.

That is, both the cutting and the polishing, which is a post-process, are performed simultaneously by swinging, and the obtained wafer may be directly subjected to lapping in some cases.

Further, according to the first embodiment, since a plurality of cutting processes can be performed simultaneously, the cutting capability is high, and the cutting loss is small because the wire used is thinner than a polishing blade or the like in the inner peripheral blade. A hard and brittle material disk having both high strength and smoothness can be obtained while maintaining the features of a conventional wire saw.

Further, by swinging as shown in FIG. 5, a portion other than the vicinity of the bottom dead center of the swinging center where the ingot 1 which is the cutting portion and the wire 12 abut, is located between the wire 12 and the cut surface. Since a gap is formed in the gap, the slurry can be satisfactorily supplied to the gap.

Further, by swinging as in the first embodiment, the length of the portion where the wire 12 and the ingot 1 are in contact with each other can be made substantially uniform during cutting, and the load in cutting the wire 12 can be reduced. Fluctuations can be reduced, so that breakage, blurring, and the like of the wire 12 can be reduced.

In the first embodiment, the ingot 1 is arranged perpendicular to the moving direction of the wire 12 so as to maximize the number of wafers from which the ingot 1 can be obtained. In some cases, for example, they may be arranged at a predetermined angle instead of vertical.

Further, the position of the swing center is set to the ingot 1
As shown in FIG. 4B, the average curvature of the cutting blade pattern can be increased as shown in FIG. 4B. However, since the swing angle needs to be increased, the positions of these swing centers are It may be appropriately selected from the relationship with the diameter R of the ingot 1 to be cut, and may be adjusted using, for example, the thickness of the fixed stand 2 or the like.

In the first embodiment, the shape of the ingot is exemplified as a general columnar shape. However, the present invention is not limited to this. The effect can be obtained.

In the first embodiment, wires and loose abrasive grains are used, but it goes without saying that various known cutting methods for cutting using a wire such as a diamond wire saw can be applied.

Furthermore, in the first embodiment, the ingot, which is a hard and brittle material, is rocked, but it is also possible to rock the wire or both, and in short, there is relative rocking. The method is not limited to a special method.

(Embodiment 2) As shown in FIG. 6, an apparatus for carrying out the method for cutting hard and brittle material according to the present invention has almost the same mechanism as a conventional inner peripheral blade slicer apparatus. As a mechanism for moving the ingot 1 to be cut in a direction (Y-axis direction) perpendicular to the cutting direction (X-axis direction) on the cut surface, a rotary encoder 18 for X-axis direction movement and a rotary encoder for Y-axis direction movement Encoder 1
7, an X-axis direction moving table 16 and a Y-axis direction moving table 15 which can be arbitrarily moved in the X and Y directions.
The ingot 1, which is a hard and brittle material cut by the Y-axis direction moving table 15, is fixed, and the X-Y on which the X-axis direction moving table 16 and the Y-axis direction moving table 15 are mounted is provided. A table base table 19 is fixed to a horizontal support plate 6 connected to a vertically moving slide table 7, and the horizontal support plate 6 is moved up and down by a vertical movement rotary encoder 9 to move the Y-axis direction. The lower end of the ingot 1 fixed to the table 15 is moved downward, and the lower end of the ingot 1 is protruded by a thickness to be cut from the cut surface of the inner peripheral blade, and the ingot 1 is moved in the X-axis direction and the Y-axis direction. The cutting can be performed while arbitrarily moving.

The inner peripheral blade is rotated by a motor for moving the inner peripheral blade (not shown) so as to rotate at a high speed. At the time of cutting, a cutting oil is discharged from a discharge nozzle (not shown). It discharges more.

In the second embodiment, the rotary encoder 18 for moving in the X-axis direction, the rotary encoder 17 for moving in the Y-axis direction, and the rotary encoder 9 for moving vertically are controlled by a control computer (not shown).
Is controlled by

Hereinafter, the cutting operation of the method for cutting hard and brittle material according to the second embodiment will be described with reference to FIG. 7. The operator fixes the ingot 1 to be cut to the Y-axis direction moving table 15 and then moves the horizontal support. The plate 6 is lowered from the control computer to a position where the lower end of the ingot 1 is located on the cut surface of the inner peripheral blade.

At this stage, when the operator inputs the radius R of the ingot 1 to be cut and presses the cutting start button of the control computer, the control computer moves vertically by an amount corresponding to the thickness of the ingot 1 to be cut. Instruct the moving rotary encoder 9 to lower the horizontal support plate 6 and adjust the positions of the X-axis direction moving table 16 and the Y-axis direction moving table 15 so that the center of the ingot 1 comes to the center of the inner peripheral blade. The inner peripheral blade drive motor is driven to keep the rotational speed of the inner peripheral blade constant, and the Y axis direction rotary encoder 17 is instructed to move in the Y axis direction. The moving distance and moving speed in the X-axis direction are instructed to the encoder 18 to start cutting.

A method of controlling the moving distance in the Y-axis direction and the moving distance and moving speed in the X-axis direction used in the second embodiment will be described with reference to FIG. 7. In the second embodiment, the Y-axis from the center of the ingot is described. Assuming that the moving distance in the direction is the radius of the inner peripheral blade as L and the radius of the ingot as R, the distance is fixed at (LR), and this distance is repeatedly moved in the positive and negative directions while repeatedly moving the ingot 1 along the X axis. The cutting is performed by moving in the direction at a predetermined speed.

The moving speed in the X-axis direction is the second embodiment.
In the case where the ingot 1 is located near the center of the inner peripheral blade at the start of cutting or near the end of cutting, there is little contact between the inner peripheral blade and the ingot 1, so the moving speed in the X-axis direction is small. When the moving distance is near the radius L of the inner peripheral blade, since the portion where the inner peripheral blade and the ingot 1 are in contact is large, the moving speed in the X-axis direction is controlled to be reduced. Since the moving speed in the direction depends on the polishing ability of the inner peripheral blade to be used, it may be appropriately selected according to the polishing ability of the inner peripheral blade to be used.

FIG. 8 schematically shows a cut surface of the ingot 1 cut in the second embodiment.
Each cutting blade pattern is similar to the blade pattern by the conventional inner peripheral blade slicer shown in FIG. 9B, but is cut once by repeatedly performing the cutting in the Y-axis direction. The inner peripheral blade can again come into contact with the cut surface on which the blade pattern is formed, and as shown in the schematic diagram of FIG. 8, since a plurality of blade patterns exist over the entire cut surface, cutting is performed. The protruding portion of the blade pattern, which is the unevenness on the surface, is polished over the entire cutting surface by the polishing blade at the tip of the inner peripheral blade, so that the unevenness on the surface of the wafer obtained by cutting can be significantly reduced, and as a result, Thus, a wafer having extremely high strength can be obtained.

In other words, the wafer is moved in the Y-axis direction to perform both cutting and polishing, which is a post-process, at the same time. In some cases, the obtained wafer can be directly subjected to lapping.

In the second embodiment, the moving direction with respect to the X axis, which is the cutting direction, is a right angle direction. However, the present invention is not limited to this. Different angles may be used for positive and negative.

In the second embodiment, the ingot 1 is moved.
It is also possible to move both relatively.

Further, the relative movement can be not only a straight line but also various other relative movements such as an eccentric movement.

In the first embodiment, the ingot 1 is arranged perpendicular to the cutting plane of the inner peripheral blade so that the number of wafers from which the ingot 1 can be obtained is maximized. When there is a directionality, it may be arranged not at a right angle but at a predetermined angle.

[0050]

The present invention has the following effects.

(A) According to the first aspect of the present invention, when the cutting means again comes into contact with the convex portion of the blade pattern formed by cutting, the unevenness of the blade pattern is averaged, so that high strength and smoothness are obtained. A hard and brittle material disk having both properties can be obtained at the same time as cutting.

(B) According to the second aspect of the present invention, the wire and the hard brittle material to be cut are relatively swung on the cut surface on which the blade pattern is formed, so that the cutting with the blade pattern is formed. The wire repeatedly traverses the convex portion on the surface (in the case of using free abrasive particles, the abrasive particles are interposed between the wire and the blade convex portion), the convex portion is polished, and this polishing action is The unevenness is averaged to form a cut surface with high smoothness.

(C) According to the third aspect of the invention, the time during which the hard and brittle material ingot, which is the object to be cut, is not processed away from the wire can be effectively reduced, and the cutting can be performed efficiently. .

(D) According to the fourth aspect of the present invention, the swing angle at which the hard and brittle material always comes into contact with the wire at almost the maximum value can be easily obtained by calculating only the cut distance. The swing angle can be controlled easily and accurately.

(E) According to the fifth aspect of the present invention, the polishing blade repeatedly contacts the convex portion of the blade pattern formed by cutting at an angle different from that of the blade pattern. Are polished and averaged, so that a cut surface having high smoothness can be obtained.

(F) According to the invention of claim 6, the semiconductor silicon wafer having this feature has high smoothness and high strength because the unevenness of the blade pattern at the time of cutting is averaged.
Not only is there little damage during the transition to the next step, but the polishing step can be shortened, and the polishing process can be omitted if necessary.

[0057]

[Brief description of the drawings]

FIG. 1 is an external perspective view of a method for cutting a hard and brittle material according to a first embodiment of the present invention.

FIG. 2 is an enlarged side view of a method for cutting a hard and brittle material according to the first embodiment of the present invention.

FIG. 3 (a) is a side view showing various parameters expressing the state of the method for cutting a hard and brittle material according to the first embodiment of the present invention. FIG. 3B is a graph showing a relationship between a cutting distance and a swing angle in the method for cutting a hard and brittle material in the first embodiment of the present invention.

FIG. 4A is a schematic view showing an example of a cutting edge pattern by a method for cutting a hard and brittle material according to the first embodiment of the present invention. (B) It is a schematic diagram which shows an example of the cutting blade pattern by the cutting method of the hard and brittle material in Embodiment 1 of this invention.

FIG. 5 is a schematic diagram showing a positional relationship between a wire and a hard and brittle material during cutting in the method for cutting a hard and brittle material according to the first embodiment of the present invention.

FIG. 6 is an external perspective view of a method for cutting a hard and brittle material according to a second embodiment of the present invention.

FIG. 7 is a schematic top view showing a cutting state of a method for cutting a hard and brittle material in Embodiment 2 of the present invention.

FIG. 8 is a schematic diagram illustrating an example of a cutting edge pattern by a method for cutting a hard and brittle material according to the first embodiment of the present invention.

FIG. 9A is a schematic view showing a cutting edge pattern by a conventional method of cutting a hard and brittle material using a wire saw. (B) It is a schematic diagram which shows the cutting blade pattern by the cutting method of the hard brittle material using the inner peripheral blade slicer which is a prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hard and brittle material (ingot) 2 Fixed stand 3 Swing table 4 Swing axis 5 Rotary encoder for swing 6 Horizontal support plate 7 Slide table 8 Slide rail 9 Rotary encoder for vertical movement 10 Guide roll 11 Wire drive motor 12 Wire 13 Drive Belt 14 Inner peripheral blade 15 Y axis direction moving table 16 X axis direction moving table 17 Rotary encoder for Y axis direction moving 18 Rotary encoder for X axis direction moving 19 XY table base

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuzo Takahashi 5 Nitmac Earl Co., Ltd. at 242 Harita-cho, Kodaira-shi, Tokyo (72) Inventor Toshihiko Hirabayashi 3-6-Yawatacho, Higashikurume-shi, Tokyo No. 22 Inside Asahi Sakae Polishing Co., Ltd. (72) Inventor Kazuo Shigenobu 4-6-8 Kojimachi, Chiyoda-ku, Tokyo

Claims (6)

[Claims] 1. A method for cutting a hard and brittle material, wherein the cutting means is again brought into contact with the cut surface of the hard and brittle material once cut to smooth the edge pattern which is an irregularity on the cut surface. 2. The method for cutting hard and brittle material according to claim 1, wherein the cutting means is a wire saw, and cuts while giving relative swing between the hard and brittle material and the wire. 3. The swing according to claim 2, wherein the swing is a pendulum swing, and a swing angle with a swing center is controlled so as to have a substantially maximum value at which the hard and brittle material always contacts the wire. The method for cutting a hard and brittle material according to the above. 4. The cutting method for a hard and brittle material according to claim 2, wherein the swing angle is variably controlled as needed based on a cutting distance. 5. The cutting means is an inner peripheral blade slicer which has a polishing blade on the inner periphery of a disk and cuts by bringing a hard and brittle material into contact with the polishing blade, and a cutting direction on a cutting plane. 2. The method for cutting a hard and brittle material according to claim 1, wherein the cutting is performed while giving a relative movement between the hard and brittle material and the inner peripheral blade slicer in a predetermined relative angle direction with respect to the direction. 6. A semiconductor silicon wafer cut out from an ingot by a cutting means, the cut surface of which is:
A semiconductor silicon wafer having a plurality of intersecting cutting blade patterns.