JP2011249392A - Processing method for sapphire wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method for a sapphire wafer which can reduce chipping and crack generation and can form a scribe line deep enough for cleavage.SOLUTION: A processing method for a sapphire wafer to perform cutting processing with a parallel cutting blade or scribing processing with a diamond scriber on the surface a (11-20) of the sapphire wafer whose principal surface is the surface c (0001) comprises a processing process which relatively displaces the cutting blade or the diamond scriber and the sapphire wafer in a parallel direction with respect to the surface a (11-20) in order to form a cut groove or a scribe line from one edge of the sapphire wafer to the other edge. In the processing process, cutting process or scribing process is performed so that there is an acute angle between the surface r (1-102) and the processing direction, which goes from the one edge of the cutting blade or the diamond scriber to the other edge, on the one edge side.

Description

  The present invention relates to a processing method for a sapphire wafer, in which a main surface is cut or scribed in a direction parallel to the a-plane (11-20) on a sapphire wafer having a c-plane (0001).

  A light emitting device such as a semiconductor laser diode (LD) or a light emitting diode (LED) that emits blue or ultraviolet light having a short wavelength is manufactured, for example, by growing an epitaxial layer of gallium nitride (GaN) on a sapphire wafer. Among them, sapphire wafers whose main surface is the c-plane are most frequently used for InGaN-based light-emitting device chips that emit green and blue light.

  In the manufacturing process of a light-emitting device, a sapphire wafer on which a plurality of light-emitting devices are formed is divided into individual light-emitting devices using a dicing apparatus, a scribing apparatus, or the like (for example, see Japanese Patent Application Laid-Open No. 5-315646).

  The dicing machine is to be processed while rotating a grindstone called a cutting blade formed by hardening superabrasive grains such as diamond and CBN (Cubic Boron Nitride) with resin or metal to a thickness of about 100 μm at a high speed of about 20000 rpm to 30000 pm. The workpiece is cut and removed by cutting into the object.

  On the other hand, the scribing device moves the workpiece and the scriber shank relative to each other while bringing the scriber shank fixed to the tip of the scribing means by brazing or the like into contact with the workpiece with a predetermined load. A ruled line called a scribe line is formed on the workpiece.

  Thereafter, an external force is applied to the workpiece using a braking device or the like, and the workpiece is cleaved and divided from the scribe line as a starting point. The dividing method using a scribe device is widely used for dividing a sapphire wafer because the dividing margin can be narrowed compared to a dicing device using a cutting blade.

JP-A-5-315646

  However, since sapphire has a high Mohs hardness, when it is cut with a cutting blade, a large chipping or crack called chipping may occur and damage the sapphire wafer. Also, when a scribe line is formed by a scribe device, there is a problem that it is difficult to form a scribe line having a depth sufficient for cleavage.

  The present invention has been made in view of the above points, and an object of the present invention is to reduce the occurrence of chipping and cracks and to provide a sapphire wafer capable of forming a scribe line having a depth sufficient for cleavage. It is to provide a processing method.

  According to the present invention, there is provided a method for processing a sapphire wafer, wherein a sapphire wafer having a c-plane (0001) as a main surface is subjected to cutting with a cutting blade or scribing with a diamond scriber parallel to the a-plane (11-20). And a machining step of forming a cutting groove or a scribe line from one end to the other end of the sapphire wafer by moving the cutting blade or the diamond scriber and the sapphire wafer in a direction parallel to the a-plane (11-20). In the machining step, the cutting blade or the diamond scriber is cut so that the angle formed by the machining direction from the one end to the other end and the r-plane (1-102) is an acute angle on the one end side. Provided is a method for processing a sapphire wafer, characterized by performing a scribe process.

  In order to solve the above-mentioned problems, the present inventor has made extensive studies on a method for processing a sapphire wafer. As a result, in a sapphire wafer having a c-plane (0001) as a main surface, the inventor is parallel to the a-plane (11-20). When cutting or scribing from one end of the wafer to the other end, cutting or scribing is performed in a direction in which the formed cutting groove or scribe line and the r-plane (1-102) form an acute angle. In comparison with the case where cutting or scribing is performed in the direction in which the cutting groove or scribing line and the r-plane (1-102) form an obtuse angle, chipping and cracking are reduced, and scribing is performed with the same load. It has been found that a deeper scribe line can be formed even if processed.

  According to the processing method of the present invention, it is possible to perform cutting with reduced generation of chipping and cracks and to form deeper scribe lines.

It is a whole block diagram of a cutting device. It is a perspective view of a scriber unit. FIG. 3 is a view in the direction of arrow III in FIG. 2. FIG. 6 is a plan view of a sapphire wafer having a c-plane (0001) as a main surface on which an orientation flat is formed on an a-plane (11-20). It is a top view explaining the processing method of the sapphire wafer by this invention. It is a unit cell figure of a sapphire single crystal, and a figure showing the processing direction of the present invention. It is explanatory drawing which shows the process direction of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration diagram of the cutting device 2. The cutting device 2 includes a pair of guide rails 6 that are mounted on a stationary base 4 and extend in the X-axis direction.

  The X-axis moving block 8 is moved in the machining feed direction, that is, the X-axis direction by an X-axis feed mechanism (X-axis feed means) 14 including a ball screw 10 and a pulse motor 12. A chuck table 20 is mounted on the X-axis moving block 8 via a cylindrical support member 22.

  The chuck table 20 has a suction part (suction chuck) 24 formed of porous ceramics or the like. A plurality of (four in this embodiment) clampers 26 for clamping the annular frame F shown in FIG.

  The X-axis feed mechanism 14 includes a scale 16 disposed on the stationary base 4 along the guide rail 6 and a read head 18 disposed on the lower surface of the X-axis moving block 8 that reads the X coordinate value of the scale 16. Including. The read head 18 is connected to the controller of the cutting device 2.

  A pair of guide rails 28 extending in the Y-axis direction are further fixed on the stationary base 4. The Y-axis moving block 30 is moved in the Y-axis direction by a Y-axis feed mechanism (index feed mechanism) 36 composed of a ball screw 32 and a pulse motor 34.

  The Y-axis moving block 30 is formed with a pair of guide rails 38 (only one is shown) extending in the Z-axis direction. The Z-axis moving block 40 is moved in the Z-axis direction by a Z-axis feed mechanism 44 composed of a ball screw (not shown) and a pulse motor 42.

  Reference numeral 46 denotes a cutting unit (cutting means), and a spindle housing 48 of the cutting unit 46 is inserted into and supported by the Z-axis moving block 40. The spindle housing 48 accommodates a spindle and is rotatably supported by an air bearing. The spindle is rotationally driven by a motor (not shown) housed in a spindle housing 48, and a cutting blade 50 is detachably attached to the tip of the spindle.

  An alignment unit (alignment means) 52 is mounted on the spindle housing 48. The alignment unit 52 has an imaging unit (imaging means) 54 that images the wafer W held on the chuck table 20. The cutting blade 50 and the imaging unit 54 are arranged in alignment in the X-axis direction.

  Referring to FIG. 2, a perspective view of a scriber unit (scriber means) 58 is shown. For example, the scriber unit 58 is assembled as a scriber by removing the spindle and the cutting blade 50 from the spindle housing 48 of FIG. 1 and fixing the block 59 of the scriber unit 58 to the end of the spindle housing 48.

  An L-shaped member 60 is attached to the block 59 with a screw 61 so that the attachment angle can be adjusted. As shown in FIG. 3, which is a view taken in the direction of arrow III in FIG. 2, a first shank holder 62 is fixed to the L-shaped member 60 with a screw 63. The first shank holder 62 has a semicircular insertion groove 62a. The second shank holder 64 also has a semicircular insertion groove 64a.

  The second shank holder 64 is brought into contact with the first shank holder 62, the scriber shank 67 of the diamond scriber 66 is inserted into the round hole 65 formed by the two semicircular insertion grooves 62a, 64a, and the screw 70 is fastened. As a result, the shank 67 is held by the first and second shank holders 62 and 64 as shown in FIG. For example, a square frustum-shaped diamond chip 68 is fixed to the tip of the scriber shank 67 by brazing or the like.

  Hereinafter, the processing method of the present invention for processing a sapphire wafer using the above-described scribing apparatus 2 having the cutting apparatus 2 or the diamond scriber 66 will be described with reference to FIGS.

  Referring to FIG. 4, a plan view of a sapphire wafer 11 to be processed by the processing method of the present invention is shown. The sapphire wafer 11 is formed by cutting from a sapphire ingot so that the main surface 13 becomes a c-plane (0001).

  An orientation flat 15 is formed on the sapphire wafer 11, and this orientation flat 15 extends in a direction parallel to the a-plane (11-20). Actually, the orientation flat 15 is formed in parallel with the a-plane in the state of a sapphire ingot, and then sliced into individual sapphire wafers 11.

  The sapphire wafer 11 has crystal axes a1, a2, and a3. As is well known, an epitaxial layer made of GaN is formed on the main surface 13 of the sapphire wafer 11, and each region partitioned by the predetermined division lines formed in a lattice shape on the epitaxial layer is formed. An LED is formed.

  Referring to FIG. 6, the relationship between the unit cell diagram of the sapphire single crystal and the processing direction P of the present invention is shown. That is, according to the present invention, when processing from one end of the sapphire wafer to the other end in a direction parallel to the a-plane (11-20) of the sapphire wafer, the angle formed by the processing direction and the r-plane (1-102) is one end side. It has been found that when processing is performed so as to have an acute angle, chipping and cracking can be reduced, or deeper scribe lines can be formed.

  Referring to FIG. 7A, when cutting with the cutting blade 50 from one end 11a to the other end 11b of the sapphire wafer 11 in a direction parallel to the a-plane (11-20), the r-plane (1-102) and The relationship with the processing direction P of the present invention is schematically shown. FIG. 7B is a schematic enlarged view of the processing direction.

  7A, the sapphire wafer 11 is sucked and held by the chuck table 20 of the cutting apparatus, and the chuck table 20 is processed and fed in the direction of arrow Q. Therefore, the processing direction by the cutting blade 50 is the arrow P direction.

  That is, in the processing method of the present invention, as shown in the enlarged schematic view of FIG. 7B, the cutting blade 50 and the sapphire wafer 11 are relatively moved in a parallel direction with respect to the a-plane (11-20), When the cutting groove is formed from the one end portion 11a to the other end 11b of the sapphire wafer 11, the cutting is performed so that the angle θ formed by the cutting direction P and the r-plane (1-102) is an acute angle on one end side. It is characterized by that. By performing cutting in such a direction, it is possible to reduce the occurrence of chipping and cracks during sapphire wafer cutting.

  The processing method of the present invention can be similarly applied to the scribe processing by the diamond scriber 66. That is, when the diamond scriber 66 and the sapphire wafer 11 are moved relative to each other in the direction parallel to the a-plane (11-20) to form a scribe line from one end 11a of the sapphire wafer 11 to the other end 11b. The scribing process is performed so that the angle θ formed by the processing direction P and the r-plane (1-102) is an acute angle on the one end 11a side. By performing such scribing, a deeper scribe line can be formed.

2 Cutting device 11 Sapphire wafer 13 c-plane (0001)
15 Orientation flat 20 Chuck table 50 Cutting blade 58 Scriber unit 66 Diamond scriber P Machining direction Q Chuck table moving direction

Claims (1)

A processing method of a sapphire wafer, wherein a main surface is a c-plane (0001) sapphire wafer, which is subjected to cutting with a cutting blade or scribe processing with a diamond scriber parallel to the a-plane (11-20),
A machining step of forming a cutting groove or a scribe line from one end of the sapphire wafer to the other end by moving the cutting blade or the diamond scriber and the sapphire wafer in a direction parallel to the a-plane (11-20). ,
In the machining step, cutting or scribing so that an angle formed by the machining direction from the one end of the cutting blade or the diamond scriber to the other end and the r-plane (1-102) is an acute angle on the one end side. A method for processing a sapphire wafer, characterized by:

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