JPH09168947A - Work periphery grinding method by ultrasonic micro vibration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To machine a machining surface at a 19 precision without applying chipping or scratching to it, to lengthen the life of a grinding wheel, to decrease rigidity of a finishing machine, to miniaturize the machine, and to perform precision finishing with coarse abrasive, grains. SOLUTION: A silicon wafer 9 is rotated at the revolution per minute in the range of 2 to 44RPM, a ultrasonic diamond grinding wheel 3 in which a recessed part to which diamond abrasive grains are stuck is annularly provided on the tip is rotated, the recessed part is pressed to the periphery of the silicon wafer 9, simultaneously, ultrasonic micro vibration having frequency in the range of 20 to 60kHz and amplitude in the range of 0.1 to 20 microns is applied to the ultrasonic diamond grinding wheel 3.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicon wafer
The present invention relates to a technique for grinding and shaping the outer peripheral edge of a brittle material such as glass into a desired shape by using ultrasonic microvibration.

[0002]

2. Description of the Related Art Silicon wafers are often used as semiconductor substrates. This silicon wafer is processed into a disk shape and supplied to an IC production factory for use. Since a silicon wafer is very likely to be chipped, the outer peripheral edge of a disk-shaped silicon wafer is rounded into a fixed shape. A conventional method for processing the outer peripheral edge of a brittle material such as a silicon wafer is an outer peripheral rounding machine for processing by rotating an abrasive wheel of diamond abrasive grains at an ultra-high speed of 8,000 to 80,000 RPM with an air spindle or a supersonic spindle. Was using. Since it rotates at ultra-high speed, the machine needs high mechanical rigidity and becomes large in size.
It required a large device space. Further, the diamond abrasive grains 20 and the grain removal thereof deeply scratch the work surface of the work 9 and damage it, and the generation of deep scratches on the work surface cannot be avoided. In addition, since the diamond abrasive grains 20 are constantly in contact with the machined surface of the work 9, the chips 21 are accumulated between the diamond abrasive grains 20 and cause clogging, which increases the machining resistance and cracks due to the pressure due to the machining resistance. 22 was generated inside the work (see FIG. 8). Even if the grinding liquid 23 was poured into the processed surface of the work, this phenomenon could not be sufficiently solved. Therefore, a processing method of rough grinding to finish grinding is adopted in two or three steps in which the diameter of the abrasive grains of the grindstone is gradually reduced. Even so, the grinding process was lengthened due to the clogging of the whetstone and shattering.

[0003]

SUMMARY OF THE INVENTION The problems to be solved by the present invention are to solve these conventional problems, enable high-precision machining without chipping and scratching of the machined surface, and a grinding tool. The present invention provides a method for grinding the periphery of a work by ultrasonic microvibration, which can increase the life of the machine, reduce the rigidity of the machine, reduce the size of the machine, and perform fine finishing with coarse abrasive grains.

[0004]

Means for Solving the Problems The constitution of the present invention which has solved the above problems is as follows: 1) A recess having a female cross-sectional shape, which is the cross-sectional shape of the periphery of a workpiece, is annularly provided on the outer periphery, and abrasive grains are provided on the surface of the recess. While rotating the attached disk-shaped grinding rotary tool, bring the grinding rotary tool and the work closer so that the concave surface contacts the periphery of the workpiece being rotated or linearly moved, and at the same time the concave surface of the grinding rotary tool Ultrasonic micro-vibration is applied to the grinding rotary tool so that the abrasive grains vibrate at high speed at a high speed at a right angle to the machining surface on the peripheral edge of the work, and moreover, the grinding fluid is caused to flow toward the machining surface on the peripheral edge of the work, Ultrasonic waves characterized by grinding the peripheral edge of a workpiece into the concave shape of a rotary grinding tool by repeating minute cutting and crushing of the abrasive grains on the concave surface to the peripheral surface of the workpiece by ultrasonic micro vibration Method of grinding peripheral edge of workpiece by vibration 2) The workpiece is a disk-shaped silicon wafer, and the disk-shaped grinding rotary tool is attached to the rotary spindle axis end that vibrates ultrasonically, and the concave part of the disk-shaped grinding rotary tool is attached to the outer peripheral edge of the workpiece. And the disk-shaped grinding rotary tool is superposed with rotation and ultrasonic micro-vibration by a rotary spindle so that the peripheral edge of the silicon wafer is rounded, and the peripheral micro-vibration method for the workpiece by ultrasonic micro-vibration 3) The whole work is moved toward the rotating rotary grinding tool to which ultrasonic microvibration is applied, and the rotary grinding tool cuts little by little to form and grind a groove extending in the radial direction on the peripheral edge of the workpiece 1) or 2). The peripheral edge grinding method of the work by the ultrasonic microvibration described in 4) The width of the microvibration of the abrasive grains on the recessed surface by the ultrasonic microvibration is 0.1 to 20 microns. The method for grinding a peripheral edge of a workpiece by ultrasonic microvibration according to any one of 1) to 3) above.

[0005]

In the present invention, while the work is slowly fed linearly or rotated at a low speed of about 2 to 4 RPM, the concave portion of the grinding rotary tool is pressed against the peripheral edge of the work, and 300 to
Rotate at about 5,000 RPM and 20 ~ 60KH
A zigzag of about 0.1 to 20 microns (with a peak-peak width) is applied to ultrasonic microvibration. The grinding rotary tool is pressed against the work while being subjected to ultrasonic micro-vibration, so that the abrasive grains in the recess of the grinding rotary tool repeat micro-vibration at high speed in the orthogonal direction toward the work surface at the periphery of the work, Efficiently grinds by performing many small cuts and recesses so as to crush the work surface. At the same time, the crushed and dropped abrasive grains are moved by ultrasonic micro-vibration to reliably capture the liquid or gaseous grinding fluid flowing in the machining portion and remove it together with the fluid from the machining portion. This causes scratches caused by the falling abrasive grains,
Prevents damage caused by cutting chips (crushed powder) and functional deterioration of grinding tools due to clogging by cutting chips, improving processing accuracy,
Increase grinding power. In particular, even if the work is a brittle material such as a silicon wafer and is easily chipped, there is little chipping or scratching, and rounding and notching can be performed. In addition, even rough abrasive grains can be processed with high precision.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The frequency of ultrasonic microvibration used in the present invention is about 20 to 60 KHz, the vibration is about 0.1 to 20 microns, and the rotational speed of the tool is 300 to 5,000 R.
It is about PM, and appropriate values are selected for these values depending on the material of the work and the processing steps. The abrasive grains of the ultrasonic rotating tool are preferably diamond abrasive grains because they have a high grinding force.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 (see FIGS. 1 to 5) Example 1 shown in FIGS. 1 to 5 is used for rounding the peripheral edge of a silicon wafer, and the grinding rotary tool used has a rounded concave portion on the outer peripheral edge of the disk. In this example, a diamond abrasive grain is attached to the recess. 1 is a side view showing an ultrasonic micro-vibration grinding apparatus according to a first embodiment, FIG. 2 is a front view of the same, FIG. 3 is a plan view of the same, FIG. 4 is an explanatory view showing a grinding process of the first embodiment, and FIG. 5 is an explanatory diagram showing a grinding state of Example 1. FIG.
In the figure, 1 is an apparatus main body base, 2 is an ultrasonic rotary spindle, 3 is a small-diameter ultrasonic diamond grindstone that is a grinding rotary tool, 3a is a concave portion of the ultrasonic diamond grindstone, 3
b is a diamond abrasive grain adhered to the surface of the recess, 4 is an ultrasonic spindle motor, 5 is an ultrasonic spindle motor 4 for moving the ultrasonic diamond grindstone 3 up and down along the column 6, for vertical height adjustment A slide portion, 6 is a column, 7 is a work table on which a silicon wafer 9 which is a work is placed, 8 is a work table Y-axis slide portion, and L is a grinding liquid. In the first embodiment, the silicon wafer 9 is 2 to
Slowly rotate at a rotation speed of about 4 RPM. When the ultrasonic spindle motor 4 is adjusted in vertical height with the slide portion 5 and then operated, the ultrasonic diamond grindstone 3 is 300 to
Rotated at 5,000 RPM and 20 to 60 KHz
Ultrasonic micro-vibration of 0.1 to 20 microns is applied at.
When the work table Y-axis slide portion 8 is moved and the silicon wafer 9 is pressed against the ultrasonic diamond grindstone 3, the concave portion 3a of the ultrasonic diamond grindstone 3 becomes the silicon wafer 9
The peripheral edge of the silicon wafer 9 is ground by the diamond abrasive grains 3b of the concave portion 3a which is in contact with the peripheral edge of and rotates at a high speed. Recess 3
a is ultrasonic microvibration of 20 to 60 KHz, and generates a strong grinding force so as to crush the peripheral edge of the silicon wafer by repeating fine cutting and retreating toward the rotation center of the silicon wafer 9. The abrasive grains of the grindstone 3 expand and contract due to ultrasonic microvibration, and at the moment when the grindstone 3 expands, it collides with the silicon wafer 9 and crushes the peripheral surface of the work into minute pieces. ~ 20 microns spread, grinding fluid L intrudes into the gap, and fragments and chips melt into the grinding fluid L. Since chips do not collect, the grindstone 3 will not be clogged (see FIGS. 4 and 5). Therefore, the peripheral edge of the silicon wafer 9 is efficiently and accurately ground by the concave portion 3a without any damage, and the cross-sectional shape of the peripheral edge of the silicon wafer 9 is processed in accordance with the shape of the concave portion 3a, resulting in a rounded state. For example, when the diamond grindstone # 800 was used for grinding in Example 1, the finish was equivalent to that of the conventional grinder # 2,000. The present invention is not limited to the first embodiment, and the roughing process to the precise finishing process can be performed with a single grindstone, and the grinding process can be omitted to enable rapid processing. Further, since the rotational speed of the ultrasonic diamond grindstone 3 of the grinding rotary tool is considerably lower than the conventional rotational speed of 8,000 to 80,000 RPM and the grinding processing resistance is low, the main body 1 of the apparatus, the ultrasonic spindle. The motor 4, the column 6, the vertical height adjusting slide portion 5 and the like can be made compact. Example 2 (see FIGS. 6 and 7) Example 2 shown in FIGS. 6 and 7 is an example in which a groove is formed in a notch of a silicon wafer. FIG. 6 is an explanatory view showing the second embodiment, and FIG. 7 is a plan view showing the silicon wafer processed in the second embodiment. In the figure, 10 is an ultrasonic spindle, 11 is a small-diameter ultrasonic grindstone for notching, which is a rotary grinding tool,
Reference numeral 11a is a concave portion of the ultrasonic grindstone 11, to which diamond abrasive grains are attached. Reference numeral 12 is a silicon wafer, and 13 is a notch groove. In the second embodiment, the silicon wafer 12 is rotated while rotating the small-diameter ultrasonic grindstone 11 at 300 to 5,000 RPM while applying 40 to 60 KHz ultrasonic microvibration with a vibration width of 0.2 to 10 microns. By moving in the direction of the ultrasonic grindstone 11, the notch groove 13 is ground in the silicon wafer by the ultrasonic grindstone 11. Example 2
However, since ultrasonic micro-vibration is applied to the ultrasonic grindstone 11, similar to the first embodiment, the peripheral edge of the silicon wafer 12 is finely cut and crushed / retracted repeatedly to repeat the recess 1 of the ultrasonic grindstone 11.
1a, the silicon wafer 12 is ground toward the center to form the notch groove 13. The cross-sectional shape of the peripheral edge of the groove 13 is rounded according to the cross-sectional shape of the recess 11a.

[0008]

As described above, according to the present invention, by rotating the grinding tool having the concave portion while applying the ultrasonic micro-vibration, a high grinding force can be obtained and the surface of the work can be highly accurately without being scratched. Grinding is possible, and the processing equipment is compact and lightweight. More specifically, the effect of the lack can be obtained. Therefore, 1) The combined superposition grinding of rotation and ultrasonic micro-vibration has extremely small incision at the tip of the abrasive grain of the grindstone, as compared with the ultra-high speed forming grinding of the conventional machining method. Since it gradually wears off from the tip, scratches are not scratched on the machined surface due to the removal of abrasive grains. 2) The combined grinding of rotation and ultrasonic micro-vibration makes the tip of the abrasive grains act extremely small compared to the ultra-high speed forming grinding of the conventional processing method, so the processing scratches on the processed surface are extremely shallow, The depth of the damage layer becomes extremely shallow. For example, in the case of the silicon processing grindstone # 400, the damage layer is 20 to 100 μm or more in the conventional grinding method, but the damage layer is 10 μm or less in the ultrasonic grinding method of the present invention, which is greatly reduced. 3) Compared with the ultra-high-speed form grinding process of the conventional machining method, the combined grinding of rotation and ultrasonic micro-vibration has a grinding resistance of 5 compared with the conventional machining method when machining the same machining area.
~ 20% or less, so the power consumption of the processing machine is 30%
Hereafter, the weight of the processing machine can be reduced, the installation area is 30% or less, and the air consumption for the ultra-high speed spindle is not consumed. The effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view showing an ultrasonic micro-vibration grinding apparatus according to a first embodiment.

FIG. 2 is a front view showing the ultrasonic micro-vibration grinding apparatus according to the first embodiment.

FIG. 3 is a plan view showing an ultrasonic micro-vibration grinding apparatus according to a first embodiment.

FIG. 4 is an explanatory diagram showing a grinding process of Example 1.

FIG. 5 is an explanatory diagram showing a grinding state of the first embodiment.

FIG. 6 is an explanatory diagram showing a second embodiment.

7 is a plan view showing a silicon wafer processed in Example 2. FIG.

FIG. 8 is an explanatory diagram showing a conventional grinding process using diamond abrasive grains.

[Explanation of symbols]

 1 Equipment main body base 2 Ultrasonic rotary spindle 3 Ultrasonic diamond grindstone 3a Recess 3b Diamond abrasive grains 4 Ultrasonic spindle motor 5 Vertical slide part 6 Column 7 Worktable 8 Worktable Y-axis slide part 9 Silicon wafer 10 Ultrasonic spindle 11 Ultra Sonic whetstone 11a Recess 12 Silicon wafer 13 Notch

Claims (4)

[Claims] 1. A surface of a recess is rotated while rotating a disk-shaped grinding rotary tool in which a recess having a female-shaped cross-section of a peripheral edge processed cross-section of a work is annularly formed on the outer periphery and abrasive grains are adhered to the surface of the recess. Or, the grinding rotary tool and the work are brought close to each other so as to come into contact with the peripheral edge of the workpiece which is linearly moved, and at the same time, the abrasive grains on the concave surface of the rotary rotary tool vibrate at a high speed at a right angle toward the processing surface of the peripheral edge of the workpiece. Micro-vibration is applied to the grinding rotary tool so that the grinding fluid is caused to flow toward the working surface of the peripheral edge of the work, and the abrasive grains on the concave surface of the grinding rotary tool are transferred to the peripheral surface of the work by ultrasonic micro-vibration. A method of grinding a peripheral edge of a work by ultrasonic micro-vibration, which grinds the peripheral edge of the work into a concave shape of a rotary grinding tool by repeating micro-cutting crushing and retreating. 2. The work is a circular silicon wafer,
A rotary disc spindle grinding tool is attached to the rotary spindle axis where ultrasonic vibration is applied, and the concave portion of the rotary disk grinding tool is pressed against the outer peripheral edge of the workpiece. The rotary spindle superimposes rotation and ultrasonic vibration on the rotary disk grinding tool. 2. The method for grinding a peripheral edge of a work by ultrasonic micro-vibration according to claim 1, wherein the peripheral edge of the silicon wafer is rounded by being given to the workpiece. 3. The whole work is moved toward the rotating rotary grinding tool to which the ultrasonic microvibration is applied, and the rotary grinding tool cuts little by little to form and grind a groove extending in the radial direction on the peripheral edge of the work. Item 3. A method for grinding a peripheral edge of a work by ultrasonic microvibration according to Item 1 or 2. 4. The method for grinding a peripheral edge of a workpiece by ultrasonic micro-vibration according to claim 1, wherein the width of the micro-vibration of the abrasive grains on the surface of the recess due to the ultrasonic micro-vibration is 0.1 to 20 μm.