JP2004262179A - Wire saw cutting method and equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and simply cut a wafer having a main surface of a specific crystal face azimuth from a single crystal ingot. <P>SOLUTION: An arbitrary first ingot 1 is placed on stages 2 and 3 to be subjected to first cutting by a wire saw 13 and a first cut plane including a first cut surface is specified by a plane detecting sensor 22. A second ingot 1 is placed on the stages in place of the first ingot and the plane detecting sensor is applied to the reference cross section 1a of the second ingot to adjust the stages so as to make the reference cross section parallel to the first cut plane before the second ingot is cut by the wire saw. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for cutting a single crystal ingot using a wire saw and equipment therefor, and more particularly to a wire saw cutting method for cutting a wafer from a columnar single crystal ingot such as a semiconductor or a dielectric and an improvement in equipment for the same.
[0002]
[Prior art]
When a wafer is cut out from a columnar or prismatic single crystal ingot, an inner peripheral edge slicer, an outer peripheral edge slicer, a wire saw, or the like is generally used.
[0003]
By the way, it is often required that a main surface of a wafer such as a semiconductor or a dielectric used for an electronic component should have a specific crystallographic orientation. For example, when each of a plurality of wafers cut out from one columnar single crystal ingot should have a specific principal plane orientation A, first, at one end of the columnar ingot, a reference cross section having the plane orientation A with high accuracy is formed. It is formed.
[0004]
When such a reference cross section is formed, generally, the crystal orientation of the ingot is obtained by X-ray diffraction, and the first cross section is formed by a slicer so as to generate the plane orientation A at the end of the columnar ingot based on the crystal orientation. Then, measurement is again performed by X-ray diffraction to confirm that the first cross section is correctly coincident with the plane orientation A. If the first cross section is shifted from the plane orientation A by an angle difference of a predetermined allowable amount or more. If so, the second section is formed again by the slicer so as to correct the deviation angle. Such an operation is repeated until the end surface of the columnar ingot becomes a reference cross section that matches the plane orientation A with a predetermined high accuracy.
[0005]
After the reference cross section having the plane orientation A is formed at the end of the columnar ingot with high precision in this manner, a plurality of wafers having the main plane of the plane orientation A are provided by, for example, a multi-wire saw facility as shown in FIG. Can be cut out at the same time. In the drawings of the present application, the same reference numerals represent the same or corresponding parts.
[0006]
In the multi-wire saw installation shown in the schematic perspective view of FIG. 4, a columnar single crystal ingot 1 having a reference cross section 1 a having a plane orientation A is fixed to a fixing jig 3 via a carbon jig 2. The carbon jig 2 is used to prevent and hold the wafer cut from the ingot 1 from falling. The fixing jig 3 is set on the turning stage 11. A plurality of wires 13 are wound around the head roller 12. These wires 13 are moved along the longitudinal direction of the wires themselves by the rotation of the head roller 12. As the wire 13, for example, a piano wire can be used. Then, a cutting oil mixed with abrasive grains such as SiC or diamond is applied to the surface of the wire 13 at the time of cutting.
[0007]
[Problems to be solved by the invention]
When a plurality of wafers having a plane orientation A are actually cut out from a columnar ingot in a multi-wire saw facility as shown in FIG. 4, first, as shown in a schematic top view of FIG. The rotating stage 11 is adjusted while visually confirming that the wire 13 and the wire 13 are parallel. The dotted line in the drawing represents a crystallographic virtual plane to be cut, and the reference cross section 1a is formed parallel to this virtual plane. Alternatively, the rotary stage 11 is adjusted so that the reference cross section 1a and the wire 13 are parallel to each other using a tool scope 14 as shown in FIG. ).
[0008]
Thereafter, as shown by a white arrow in the schematic side view of FIG. 6, the rotary stage 11 is moved up and down while the movement of the reference section 1 a is measured by the dial gauge 16. Here, if the scale of the dial gauge 16 changes while the rotary stage 11 is moving up and down, it means that the reference cross section 1a is not parallel to the vertical direction of the rotary stage 11. Therefore, in this case, as shown by the black arrow in FIG. 6, the inclination of the fixing jig 3 is adjusted by an inclination adjustment stage (not shown), whereby the reference section 1a and the rotation stage 11 are adjusted. The vertical direction is set in parallel.
[0009]
However, when the wafer is actually cut out after the relative relationship between the reference cross section 1a and the wire 13 is initially set as described above, the main surface of the obtained wafer is not exactly parallel to the reference cross section 1a. There is. The causes include an error in setting the parallelism between the reference cross section 1a and the wire 13 visually or using the tool scope 14, and an error between the reference cross section 1a and the vertical direction of the rotary stage 11 using the dial gauge 16. An error in setting the parallelism, and an error due to the influence of the force applied to the wire 13 at the time of the actual cutting can be considered.
[0010]
Therefore, an object of the present invention is to provide a wire saw cutting method capable of accurately and easily cutting a wafer having a main surface having a specific crystal plane orientation from a single crystal ingot, and an object thereof.
[0011]
[Patent Document 1]
JP-A-2002-331518
[Means for Solving the Problems]
According to the present invention, a method for cutting out a wafer having a main surface parallel to a reference cross-section formed at least at one end of a columnar single crystal ingot with a wire saw using a wire saw is to place an arbitrary first ingot on a stage. The first cutting plane including the first cutting plane is specified by applying a plane detection sensor capable of specifying the orientation of the plane to the first cutting plane of the first ingot by performing the first cutting with the wire saw. A second ingot is placed on the stage in place of the first ingot, and the plane detection sensor is applied to the reference section of the second ingot, and the stage is adjusted so that the reference section is parallel to the first cutting plane. Then, the second ingot is cut with a wire saw.
[0013]
This makes it possible to easily cut out a wafer having a main surface parallel to the reference cross section with high accuracy. Note that a dummy ingot can be used as the first ingot, and the first cut can be a test cut.
[0014]
Further, such a wire saw cutting method can be carried out in a wire saw cutting facility including a stage, a wire saw, and a plane detection sensor. The plane detection sensor can identify the orientation of a plane including the plurality of measurement points by detecting the positions of three or more measurement points that are not on the same straight line. It is preferable that the plane detecting sensor includes four point sensors capable of detecting the positions of two points in the vertical direction and two points in the horizontal direction.
[0015]
The wire saw cutting equipment may include a side wall and a guide rail detachable from the side wall, and the flat detection sensor may slide on the guide rail. Preferably, the plane detection sensor is connected to a data processing system for processing data relating to the orientation of the specified plane.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 3, a wire saw cutting method according to an embodiment of the present invention and equipment for the method are illustrated in schematic side views.
[0017]
First, in FIG. 1, a dummy ingot 1D is placed on a carbon jig 2 on a fixing jig 3. Then, as shown by the white arrow, the dummy ingot 1D is moved up and down relatively to the wire 13, and a plurality of wafers are actually cut. As a result, a cut end face 1A is formed in the remaining portion of the dummy ingot 1D.
[0018]
In FIG. 2, a guide rail 21 is mounted on a side wall 20 of the wire saw cutting equipment, and a flat detection sensor 22 is slidably mounted thereon. The plane detection sensor 22 includes a plurality of point sensors that can detect three or more positions that are not on the same straight line. In FIG. 2, only two point sensors 22a and 22b are illustrated.
[0019]
The plane detection sensor 22 is slidable on the guide rail 21 and is applied to the cut end face 1A of the dummy ingot 1D. At this time, each of the point sensors 22a and 22b has a small spherical touch element, and the touch element is brought into contact with the cut end surface 1A. In this way, three or more positions that are not on the same straight line are detected, and thereby the plane orientation of the cut end face 1A is specified. The plane detection sensor 22 is a data processing system (not shown) including an arithmetic unit that calculates a plane direction from the detected positions of a plurality of points, a storage device that stores the data, and a display device that displays the data. )It is connected to the.
[0020]
In order to accurately and easily specify the orientation of the cross section, the plane detection sensor 22 preferably includes two point sensors in the horizontal direction and two point sensors in the vertical direction. Then, for example, when specifying the plane orientation of a circular, elliptical, or rectangular cross section of an ingot, two point sensors in the horizontal direction are applied to the vicinity of both ends in the width direction of the cross section, and at the same time, two point sensors in the vertical direction are used. One point sensor can be applied to the vicinity of both ends in the vertical direction of the cross section. Then, by applying the plane detection sensor 22 once to the cross section, the horizontal inclination and the vertical inclination of the cross section can be simultaneously specified with high accuracy.
[0021]
As described above, the plane orientation data on the cross section 1A of the dummy ingot 1D specified by the plane detection sensor 22 is stored in a data processing system (not shown).
[0022]
In FIG. 3, the flat detection sensor 22 is slid on the guide rail 21 to be separated from the cross section 1A of the dummy ingot 1D. Then, the dummy ingot 1D on the carbon jig 2 is replaced with the single crystal ingot 1. Thereafter, the plane detection sensor 22 is slid on the guide rail 21 and applied to the reference cross section 1 a of the single crystal ingot 1. That is, the touch element of each point sensor in the plane detection sensor 22 is brought into contact with the reference cross section 1a. Then, the rotation stage and the tilt adjustment stage are adjusted such that the plane orientation of the reference section 1a in contact with the tentacles of those point sensors matches the plane orientation of the section 1A stored in the data processing system. . Thereby, reference cross section 1a of single crystal ingot 1 can be set in parallel with actual cut surface 1A of dummy ingot 1D.
[0023]
Thereafter, the planar detection sensor 22 is slid on the guide rail 21 to be separated from the reference cross section 1 a of the single crystal ingot 1, and the guide rail 21 is removed from the side wall 20. Then, similarly to the case where the dummy ingot 1D is cut, a plurality of wafers are cut out from the single crystal ingot 1 by the wires 13.
[0024]
In this case, since the reference cross section 1a is set in parallel with the actual cut surface 1A of the wire saw obtained by the test cutting of the dummy ingot 1D, a plurality of wafers cut out from the single crystal ingot 1 can be all highly accurate. It may have a main surface parallel to the reference section 1a.
[0025]
In the above embodiment, a case has been described in which a plane detection sensor including a point sensor having a tentacle that makes mechanical contact with a cross section is used, but a plane including a point sensor that optically detects a position is described. It goes without saying that a detection sensor may be used. Semiconductor lasers can be used for such optical point sensors. Further, as an example of a flat panel detection sensor using a mechanical touch element, a graphic analog controller RJ-800 sold by Keyence Corporation can be obtained.
[0026]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a wire saw cutting method capable of accurately and easily cutting a wafer having a main surface having a specific crystal plane orientation from a single crystal ingot, and a facility for the method.
[Brief description of the drawings]
FIG. 1 is a schematic side view illustrating an initial step in a wire saw cutting method according to an embodiment of the present invention.
FIG. 2 is a schematic side view illustrating a step following the step of FIG. 1 in the wire saw cutting method according to one embodiment of the present invention;
FIG. 3 is a schematic side view illustrating a step following the step of FIG. 2 in the wire saw cutting method according to one embodiment of the present invention;
FIG. 4 is a schematic perspective view showing an example of a conventional wire saw cutting facility.
FIG. 5 is a schematic top view illustrating a conventional wire saw cutting method.
FIG. 6 is a schematic side view illustrating a conventional wire saw cutting method.
[Explanation of symbols]
Reference Signs List 1 single crystal ingot, 1a reference cross section, 1A dummy cut surface, 1D dummy ingot, 2 carbon jig, 3 fixing jig, 11 rotary stage, 12 head roller, 13 wires, 14 tool scope, 16 dial gauge, 20 wire saw cutting Equipment side walls, 21 guide rails, 22 flat surface detection sensors, 22a, 22b point sensors.

Claims (7)

A method of cutting out a wafer having a main surface parallel to a reference cross-section formed at least at one end of a columnar single crystal ingot with a wire saw,
Place an arbitrary first ingot on a stage and perform a first cut with the wire saw,
By applying a plane detection sensor capable of specifying the orientation of a plane to the first cut surface of the first ingot, a first cut plane including the first cut surface is specified,
Placing a second ingot on the stage instead of the first ingot,
Applying the plane detection sensor to the reference section of the second ingot, adjusting the stage so that the reference section is parallel to the first cutting plane,
Thereafter, the second ingot is cut by the wire saw. The method according to claim 1, wherein the first ingot is a dummy ingot, and the first cutting is a test cutting. A facility for carrying out the wire saw cutting method according to claim 1, wherein the facility comprises the stage, the wire saw, and the plane detection sensor. The wire saw cutter according to claim 3, wherein the plane detection sensor detects the positions of a plurality of three or more measurement points that are not on the same straight line, and specifies the orientation of a plane including the plurality of measurement points. Facility. The wire saw cutting equipment according to claim 4, wherein the plane detecting sensor includes four point sensors capable of detecting positions of two points in a vertical direction and two points in a horizontal direction. The wire saw according to any one of claims 3 to 5, wherein the wire saw cutting equipment includes a side wall and a guide rail detachable from the side wall, and the flat detection sensor is slidable on the guide rail. Cutting equipment. The wire saw cutting equipment according to any one of claims 3 to 6, wherein the plane detection sensor is connected to a data processing system for processing data on the orientation of the specified plane.

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