Processing method and processing device

Abstract

To provide a processing method and a processing device, which form a notch with accuracy to an outer edge of a compound semiconductor wafer.SOLUTION: A processing method by a processing device 100, comprises: a step of detecting a crystal direction of an attention portion of an outer edge by detecting a diffraction line while irradiating, with an X-ray, the outer edge of a compound semiconductor wafer W fixed to a support table 21a of an outer edge grinding device 20; and a step of relatively deviating a grindstone member 28 to be rotated to the compound semiconductor wafer W while rotating the compound semiconductor wafer W with the support table 21a, and forming an orientation flat as a notch to an object region OA corresponded to a desired crystal direction from the outer edge.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a processing method and processing apparatus for forming a notch in an end face of a compound semiconductor wafer. [Background technology]

[0002] As a method for forming an orientation flat or other notches on the outer periphery of a compound semiconductor wafer, there is a technique using cleavage (Patent Document 1).

[0003] A known method involves forming an orientation flat or the like on the outer periphery of a compound semiconductor wafer by cleavage, measuring the diffraction line from the orientation flat while irradiating the orientation flat with X-rays, and determining whether the difference between the direction in which the orientation flat extends and the measured crystal orientation is below a predetermined threshold value (Patent Document 2).

[0004] If the crystal orientation can be determined accurately, an orientation flat can also be formed by grinding. When forming an orientation flat on a disk-shaped compound semiconductor wafer by grinding, it is possible to measure the compound semiconductor wafer with X-rays, mark the orientation, and perform the grinding process using this marking as a reference. However, there is a risk that the processing accuracy of the orientation flat will decrease depending on the accuracy of the marking and the accuracy of mounting the compound semiconductor wafer on the grinding device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-222746 A [Patent Document 2] JP 2007-278929 A Summary of the Invention

[0006] The present invention has been made in view of the above-mentioned background art, and has an object to provide a processing method for precisely forming a notch in the outer edge of a compound semiconductor wafer.

[0007] In order to achieve the above object, the processing method of the present invention includes a step of detecting a crystal orientation of a target portion of the outer edge by irradiating X-rays onto the outer edge of a compound semiconductor wafer fixed to a support table of an outer edge grinding device and detecting diffraction lines, and a step of rotating the compound semiconductor wafer together with the support table while displacing a rotating grinding member relative to the compound semiconductor wafer to form a notch in a target region of the outer edge that corresponds to the desired crystal orientation.

[0008] In the above processing method, the crystal orientation of a target portion of a compound semiconductor wafer fixed to a support table of a peripheral grinding machine is detected, so that a notch can be formed in the compound semiconductor wafer without removing the compound semiconductor wafer from the support table after the crystal orientation has been detected. This makes it possible to easily process a notch such as an orientation flat by grinding, and makes it easy to improve the processing accuracy of the notch.

[0009] In a specific aspect of the present invention, in the above processing method, the compound semiconductor wafer fixed to the support table is placed at a measurement position where diffraction lines are detected while irradiating X-rays during measurement, and is placed at a processing position set below the measurement position during processing. In this case, the measurement position can be separated from the processing position, and interference between the crystal orientation detection device and parts of the outer edge grinding device and grinding fluid placed at or near the processing position can be avoided.

[0010] In another aspect of the present invention, an angular direction of a point of interest on the compound semiconductor wafer when it is placed at the measurement position by the support table, with reference to the rotation axis of the support table, differs by 90 degrees or more from an angular direction of a target area on the compound semiconductor wafer when it is placed at the processing position by the support table, with reference to the rotation axis of the target area on the compound semiconductor wafer. By, for example, inverting the position of the point of interest on the compound semiconductor wafer and the target area on the compound semiconductor wafer, it becomes easier to avoid interference between the outer edge grinding device and the crystal orientation detecting device.

[0011] In yet another aspect of the invention, the notch is an orientation flat.

[0012] In order to achieve the above object, a processing apparatus according to the present invention includes an X-ray source which irradiates X-rays onto a target portion of an outer edge of a compound semiconductor wafer, and a detector which detects diffraction rays from the target portion and detects the crystal orientation of the target portion, a support table which supports and fixes the compound semiconductor wafer, a grinding stone member which performs grinding processing on the outer edge of the compound semiconductor wafer fixed to the support table, and a drive device which rotates the compound semiconductor wafer and the grinding stone member while relatively displacing them, and which forms a notch in a target region of the outer edge which corresponds to a desired crystal orientation, and the crystal orientation detection device measures the compound semiconductor wafer fixed to the support table.

[0013] In the above processing apparatus, the crystal orientation detection device measures the compound semiconductor wafer fixed to the support table of the edge grinding device, so that a notch can be formed in the compound semiconductor wafer without removing the compound semiconductor wafer, whose crystal orientation has been detected, from the support table. This allows the notch to be easily processed by grinding, and makes it easy to improve the processing accuracy of the notch.

[0014] In a specific aspect of the present invention, in the above-mentioned processing apparatus, the outer edge grinding device has a lifting device that raises and lowers the compound semiconductor wafer together with the support table, and the lifting device moves the compound semiconductor wafer to a measurement position where crystal orientation is detected by the crystal orientation detection device and a processing position that is below the measurement position and where a notch is formed by the grinding stone member.

[0015] In another aspect of the present invention, the peripheral grinding apparatus manages angle information of the support table with consistency between the measurement position and the processing position. In this case, measurement and processing can be performed while associating a point of interest of the compound semiconductor wafer with a target area of ​​the compound semiconductor wafer relatively precisely. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2A is a plan view of the processing device of the embodiment, and FIG. 2B is a side view of the processing device. [Diagram 2] FIG. 2 is a plan view illustrating a wafer to be processed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a processing method and processing apparatus according to the present invention will be described with reference to the drawings.

[0018] 1(A) and 1(B), the processing apparatus 100 includes an outer edge grinding device 20, a crystal orientation detection device 30, and a control device 50. A compound semiconductor wafer W to be processed by the processing apparatus 100 is a thin disk of compound semiconductor crystal, and specifically, a GaN wafer.

[0019] The outer edge grinding apparatus 20 includes a supporting and rotating device 21 that supports the compound semiconductor wafer W and rotates it at a specified speed, a processing apparatus main body 22 including a grinding stone member 28 which is a tool for grinding the outer edge of the compound semiconductor wafer W, and a container 26 that prevents the grinding fluid from scattering and collects the grinding fluid. The outer edge grinding apparatus 20 forms an orientation flat OF which is a notch CO in a target area OA corresponding to a desired crystal orientation in the outer edge EO of the compound semiconductor wafer W shown in FIG.

[0020] In the outer edge grinding apparatus 20 shown in FIG. 1, the supporting and rotating device 21 includes a support table 21a that supports the compound semiconductor wafer W, a first rotary drive device 21b that rotates and raises and lowers the compound semiconductor wafer W together with the support table 21a, and an angle sensor 21d that detects the angular direction of the support table 21a.

[0021] The support table 21a has a mechanism (not shown) for fixing the compound semiconductor wafer W by suction or the like. A positioning mechanism for mechanically aligning the compound semiconductor wafer W on the support table 21a before fixing can be provided in association with the support table 21a.

[0022] The first rotation drive device 21b includes a rotation device 21i that rotates the compound semiconductor wafer W on the support table 21a around a rotation axis RX1 at a desired speed, and a lifting device 21j that lifts and lowers the support table 21a together with the rotation device 21i in the ±Z directions parallel to the rotation axis RX1 at a desired timing.

[0023] The lifting device 21j moves the compound semiconductor wafer W between a measurement position P1 where the crystal orientation is detected by the crystal orientation detection device 30 and a processing position P2 which is below the measurement position P1 and where an orientation flat OF (see Figure 2) is formed by the grinding stone member 28.

[0024] The angle sensor 21d detects the rotation angle of the support table 21a around the rotation axis RX1, thereby monitoring the relative angular orientation of the compound semiconductor wafer W on the support table 21a.

[0025] In the outer edge grinding device 20, the processing device body 22 includes a second rotation drive device 22b that moves the grindstone member 28 one-dimensionally or two-dimensionally relative to the compound semiconductor wafer W while rotating the grindstone member 28 around the rotation axis RX2 at a predetermined speed. Although not shown, the second rotation drive device 22b includes a position sensor that monitors the X-direction position and the Z-direction position of the grindstone member 28. A combination of the second rotation drive device 22b of the processing device body 22 and the first rotation drive device 21b of the supporting and rotating device 21 is referred to as a drive device 23.

[0026] The outer edge grinding device 20 is capable of adjusting the advance / retract position of the grindstone member 28 in the X direction by the processing device body 22 in accordance with the rotation angle of the support table 21a of the support rotation device 21. This makes it possible to form a notch or other cutout having a desired shape, not limited to an orientation flat OF (see FIG. 2), in the target area OA of the outer edge EO of the compound semiconductor wafer W.

[0027] The crystal orientation detecting device 30 has, within a case 30c, an X-ray source 31 that emits X-rays L1, a detector 32 that detects diffracted rays L2, and a signal processing circuit 33. The X-ray source 31 irradiates an inspection area DA that corresponds to a point of interest PI on the outer edge EO of the compound semiconductor wafer W with X-rays L1 (see FIG. 2). The detector 32 detects the diffracted rays L2 from the inspection area DA. The signal processing circuit 33 digitizes and outputs an intensity signal of the diffracted rays L2 detected by the detector 32.

[0028] In relation to the crystal orientation detection device 30, the support and rotation device 21 of the outer edge grinding device 20 functions as a device for setting the outer edge of the compound semiconductor wafer W in the inspection area DA, and the support and rotation device 21 can be regarded as a part of the crystal orientation detection device 30. Furthermore, the detection of the intensity signal of the diffraction line L2 by the detector 32 is premised on grasping the rotation angle of the compound semiconductor wafer W, and in this sense, the support and rotation device 21 of the outer edge grinding device 20 can be regarded as a part of the crystal orientation detection device 30. Here, the support and rotation device 21 can position the compound semiconductor wafer W at the measurement position P1 while the compound semiconductor wafer W is fixed on the support table 21a, and can position the compound semiconductor wafer W at the processing position P2. The measurement position P1 is relatively located on the upper side along the rotation axis RX1, and the processing position P2 is relatively located on the lower side along the rotation axis RX1.

[0029] The control device 50 is a computer, and controls the operation of the outer edge grinding device 20, and controls the operation of the crystal orientation detection device 30 or the signal processing circuit 33. When the crystal orientation detection device 30 is operated for measurement, the compound semiconductor wafer W fixed to the support table 21a is placed at the measurement position P1, where the diffraction line L2 is detected while the X-ray L1 is irradiated. At this time, the rotation angle of the compound semiconductor wafer W is monitored by using the output of the angle sensor 21d provided on the support rotation device 21. Therefore, by recording the intensity signal output from the detector 32 detecting the diffraction line L2 via the signal processing circuit 33 while gradually rotating the support table 21a of the support rotation device 21, the relationship between the rotation angle of the compound semiconductor wafer W and the X-ray intensity, which is the output of the detector 32, can be obtained. In a specific embodiment, when the rotation angle of the compound semiconductor wafer W is increased within a predetermined angle range while detecting the intensity of X-rays output from the detector 32, the rotation angle of the compound semiconductor wafer W at which the intensity of X-rays output from the detector 32 becomes maximum gives the crystal orientation of the compound semiconductor wafer W.

[0030] 2, when the compound semiconductor wafer W is a GaN wafer, for example, the (1-100) plane and six planes equivalent thereto appear as crystal planes on the outer edge EO of the compound semiconductor wafer W. That is, when the compound semiconductor wafer W fixed on the support table 21a shown in FIG. 1 is rotated once and the X-ray intensity output from the detector 32 is measured, an intensity peak of the diffraction line L2 is detected every time the support table 21a or the compound semiconductor wafer W rotates 60°, and the rotation angle output by the angle sensor 21d when the intensity peak is detected corresponds to a state in which the (1-100) plane of the compound semiconductor wafer W or a plane equivalent thereto is parallel to the horizontal Y direction. This rotation angle is called, for example, a reference angle. When the compound semiconductor wafer W is in the reference angle position, the (1-100) plane of the compound semiconductor wafer W and a virtual plane equivalent thereto are composed of a total of six planes that are based on a plane parallel to the Y direction and rotated in increments of 60° around the Z axis.

[0031] The illustrated compound semiconductor wafer W is formed by growing a GaN epitaxial layer Ws on a circular substrate B that is an integrated combination of many hexagonal GaN element substrates We, using a vapor phase growth method such as HVPE (hydride vapor phase epitaxy). Here, the (1-100) plane of each GaN element substrate We corresponds to the (1-100) plane of the compound semiconductor wafer W as a whole. The compound semiconductor wafer W can be produced by various methods, not limited to those obtained by the above method.

[0032] The crystal orientation detecting device 30 described above may be one that increases or decreases the incident angle θ1 of the X-ray L1 and the reflection angle θ2 of the diffraction line L2 in a consistent manner, or may be one that can adjust the incident angle θ1 and the reflection angle θ2 individually. In the crystal orientation detecting device 30, the detector 32 measures the peak value of the diffraction line L2, but the detector 32 may also measure the pattern of the diffraction line L2.

[0033] Returning to FIG. 1, the outer edge grinding device 20 performs grinding on the outer edge of the compound semiconductor wafer W based on angle information corresponding to the crystal orientation measured by the crystal orientation detection device 30. That is, the outer edge grinding device 20 manages the angle information of the support table 21a with consistency between the measurement position P1 and the processing position P2. This allows measurement and processing to be performed while relatively accurately associating the attention point PI of the compound semiconductor wafer W with the target area OA of the compound semiconductor wafer W. At this time, the reference axis or reference orientation for the measurement by the crystal orientation detection device 30 extends in the -Z direction from the rotation axis RX1 of the support table 21a. Also, the reference axis or reference orientation for the grinding process by the outer edge grinding device 20 extends in the +Z direction from the rotation axis RX1 of the support table 21a. As a result, an angular direction D1 based on the rotation axis RX1 of the support table 21a of the point of interest PI of the compound semiconductor wafer W when it is placed at the measurement position P1 by the support table 21a and an angular direction D2 based on the rotation axis RX1 of the target area OA of the compound semiconductor wafer W placed at the processing position P2 by the support table 21a are different by 180 degrees and are reversed. By thus reversing the positions of the point of interest PI of the compound semiconductor wafer W and the target area OA of the compound semiconductor wafer W during measurement and processing, it becomes easier to avoid interference between the outer edge grinding device 20 and the crystal orientation detection device 30.

[0034] The above is merely an example, and the angular direction D1 of the point of interest PI of the compound semiconductor wafer W placed at the measurement position P1 and the angular direction D2 of the target area OA of the compound semiconductor wafer W placed at the processing position P2 are not limited to being 180 degrees different, but as long as they are 90 degrees or more different, interference between the outer edge grinding device 20 and the crystal orientation detection device 30 can be easily avoided.

[0035] A specific processing step will be described. First, the support table 21a of the support rotation device 21 of the outer edge grinding device 20 is moved downward, and the compound semiconductor wafer W is set on the support table 21a while being aligned, that is, while being centered. In this state, the compound semiconductor wafer W is temporarily placed at the processing position P2. Then, the support table 21a of the support rotation device 21 is raised, and the compound semiconductor wafer W is set at the measurement position P1. As a result, one point of the outer edge EO of the compound semiconductor wafer W is placed in the inspection area DA, and the target point PI of the compound semiconductor wafer W is placed in the inspection area DA. Then, the support table 21a is rotated to gradually move the target point PI, and a rotation angle at which the detection intensity of the diffracted light L2 is at its peak is searched for, and the rotation angle at which the detection intensity of the diffracted light L2 is at its peak is set as the reference angle. Next, the support table 21a of the support rotation device 21 is lowered, and the compound semiconductor wafer W is set at the processing position P2. Furthermore, the support table 21a is rotated to rotate the compound semiconductor wafer W so that the compound semiconductor wafer W is in an inverted state rotated 180 degrees from the reference angle. That is, the target point PI where the detection intensity of the diffracted light L2 is at its peak is located in the +Z direction with respect to the rotation axis RX1. Thereafter, the processing device main body 22 is operated to rotate and displace the grindstone member 28, and the support rotation device 21 is operated in synchronization with this to adjust the rotational attitude of the compound semiconductor wafer W, thereby grinding the target point PI where the detection intensity of the diffracted light L2 is at its peak in the compound semiconductor wafer W, and an orientation flat OF centered on this point can be formed. The orientation flat OF thus formed will be a (1-100) plane or a crystal plane equivalent thereto if the control of the rotation angle of the support table 21a, etc. is accurate.

[0036] The processing method of the embodiment described above includes a step of detecting the crystal orientation of a point of interest PI of the outer edge EO of the compound semiconductor wafer W fixed to the support table 21a of the outer edge grinding device 20 by irradiating X-rays L1 to the outer edge EO of the compound semiconductor wafer W fixed to the support table 21a of the outer edge grinding device 20 while detecting diffraction lines L2, and a step of rotating the compound semiconductor wafer W together with the support table 21a and displacing the rotating grinding wheel member 28 relative to the compound semiconductor wafer W to form an orientation flat OF which is a notch CO in a target area OA of the outer edge EO which corresponds to the desired crystal orientation.

[0037] According to the above processing method, the crystal orientation of the target portion PI of the compound semiconductor wafer W fixed on the support table 21a of the outer edge grinding device 20 is detected, so that the notch CO can be formed in the compound semiconductor wafer W without removing the compound semiconductor wafer W, whose crystal orientation has been detected, from the support table 21a. Therefore, the orientation flat OF, which is the notch CO, can be easily processed by grinding, and the processing accuracy of the orientation flat OF can be easily improved.

[0038] The processing apparatus 100 of the embodiment described above includes an X-ray source 31 that irradiates an X-ray L1 to a point of interest PI on the outer edge EO of the compound semiconductor wafer W, a detector 32 that detects diffracted rays L2 from the point of interest PI, and a crystal orientation detecting device 30 that detects the crystal orientation of the point of interest PI, a support table 21a that supports and fixes the compound semiconductor wafer W, a grinding stone member 28 that performs grinding processing on the outer edge EO of the compound semiconductor wafer W fixed to the support table 21a, and a driving device 23 that rotates the compound semiconductor wafer W and the grinding stone member 28 while relatively displacing them, and includes an outer edge grinding device 20 that forms an orientation flat OF that is a notch CO in a target area OA of the outer edge EO that corresponds to a desired crystal orientation, and the crystal orientation detecting device 30 measures the compound semiconductor wafer W fixed to the support table 21a.

[0039] Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment. For example, the compound semiconductor wafer W is not limited to a GaN wafer, and may be any semiconductor wafer (round wafer) whose crystal orientation has not been measured. [Explanation of symbols]

[0040] 20...Outer edge grinding device, 21...Support rotation device, 21a...Support table, 21d...Angle sensor, 21i...Rotation device, 21j...Lifting device, 22...Processing device main body, 23...Drive device, 26...Container, 28...Grinding stone member, 30...Crystal orientation detection device, 30c...Case, 31...X-ray source, 32...Detector, 33...Signal processing circuit, 50...Control device, 100...Processing device, D1, D2...Angle direction, DA...Inspection area, EO...Outer edge, L1...X-ray, L2...Diffraction line, OA...Target area, OF...Orientation flat, P1...Measurement position, P2...Processing position, PI...Point of interest, RX1, RX2...Rotation axis, W...Compound semiconductor wafer

Claims

1. detecting a crystal orientation of a target portion of an outer edge of a compound semiconductor wafer fixed to a support table of an outer edge grinding apparatus by detecting diffraction rays while irradiating the outer edge with X-rays; and rotating the compound semiconductor wafer together with the support table while displacing a rotating grinding member relative to the compound semiconductor wafer to form a notch in a target region of the outer edge that corresponds to a desired crystal orientation.

2. 2. The processing method according to claim 1, wherein the compound semiconductor wafer fixed to the support table is placed at a measurement position where the diffraction lines are detected while irradiating the X-rays during measurement, and is placed at a processing position set below the measurement position during processing.

3. 3. The processing method according to claim 2, wherein an angular direction of the target area of ​​the compound semiconductor wafer, when placed at the measurement position by the support table, with a rotation axis of the support table as a reference, differs by 90 degrees or more from an angular direction of the target area of ​​the compound semiconductor wafer, when placed at the processing position by the support table, with a rotation axis as a reference.

4. The method of claim 1 , wherein the notch is an orientation flat.

5. a crystal orientation detection device having an X-ray source for irradiating a portion of interest on an outer edge of a compound semiconductor wafer with X-rays and a detector for detecting diffracted rays from the portion of interest, and for detecting a crystal orientation of the portion of interest; an outer edge grinding device including a support table for supporting and fixing the compound semiconductor wafer, a grindstone member for grinding the outer edge of the compound semiconductor wafer fixed to the support table, and a drive device for rotating and relatively displacing the compound semiconductor wafer and the grindstone member, and for forming a notch in a target region of the outer edge corresponding to a desired crystal orientation, The crystal orientation detection device measures the wafer fixed to the support table.

6. the outer edge grinding apparatus has a lifting device that lifts and lowers the compound semiconductor wafer together with the support table, 6. The processing apparatus according to claim 5, wherein the lifting device moves the compound semiconductor wafer to a measurement position where the crystal orientation is detected by the crystal orientation detection device and a processing position that is below the measurement position and where the notch is formed by the grinding stone member.

7. The processing apparatus according to claim 6 , wherein the outer edge grinding apparatus manages angle information of the support table so as to provide consistency between the measurement position and the processing position.

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