JP2014120647A - Processing method for sapphire wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To successfully process a sapphire wafer while preventing abnormal abrasion of a cutting blade and deterioration of productivity of an optical device.SOLUTION: The method for process a sapphire wafer comprises: a cut trace formation step of forming a plurality of cut traces (63) by forming the sapphire wafer (W) intermittently along a division schedule line by a cutting blade (31); and a division step of dividing the sapphire wafer (W) into individual device chips along the division schedule line from a plurality of cut traces (63) as starting points by applying external force along the division schedule line of the sapphire wafer (W) after the cut trace formation step.

Description

  The present invention relates to a method for processing a sapphire wafer on which a reflective film is laminated, and more particularly to a method for processing a sapphire wafer used for manufacturing a light emitting diode (LED).

  A sapphire wafer is known in which semiconductor layers such as gallium nitride compounds are stacked. On the surface of the wafer, a grid-like division planned line is formed, and a light emitting device is formed in each region partitioned by the division planned line. As a method for dividing the sapphire wafer, a dividing method is proposed in which a modified layer is formed along the planned dividing line inside the substrate by laser processing, and the modified layer having reduced strength is used as a dividing starting point (for example, a patent) Reference 1).

  In the dividing method of Patent Document 1, a linear modified layer is continuously formed in the wafer along the planned dividing line by irradiating a pulse laser with a condensing point inside the wafer. Subsequently, when the adhesive tape attached to the back surface of the wafer is expanded, an external force from the adhesive tape is applied to the modified layer inside the wafer, and a crack occurs in the thickness direction starting from the modified layer. As a result, the sapphire wafer is divided into individual light emitting devices (chips) along the division planned line.

Japanese Patent No. 3762409

  By the way, since a laser irradiation apparatus is expensive, there is a demand for processing a sapphire wafer by blade dicing by a cutting apparatus. However, with blade dicing, it has been difficult to satisfactorily process a sapphire wafer with high hardness. For example, the cutting blade may cause abnormal wear during the cutting process of the sapphire wafer, and it is necessary to perform low-speed processing, which increases the processing time and decreases the productivity. Thus, many technical problems existed in blade dicing of sapphire wafers.

  The present invention has been made in view of such points, and an object thereof is to provide a method for processing a sapphire wafer that can satisfactorily process a sapphire wafer while preventing abnormal wear of a cutting blade and a decrease in productivity of an optical device. And

  The sapphire wafer processing method of the present invention is a sapphire wafer processing method for dividing a sapphire wafer into individual chips, and a chuck table for holding a sapphire wafer and a sapphire wafer held by the chuck table are cut. Cutting means provided with a cutting blade, cutting feed means for cutting and feeding the cutting means and the chuck table relatively, and indexing and feeding the cutting means and the chuck table relatively in a direction perpendicular to the cutting feed direction A cutting trace forming step of forming a plurality of cutting traces by intermittently cutting a sapphire wafer along a line to be divided by the cutting blade, and a cutting trace forming process comprising: Later, an external force is applied along the planned dividing line of the sapphire wafer. The sapphire wafer starting from the cutting marks number along the dividing lines characterized in that it is composed of a dividing step for dividing into individual chips.

  According to this structure, the cutting operation which mainly cuts only by the cutting | disconnection of the thickness direction with respect to a sapphire wafer is repeated intermittently, and a some cutting trace is formed along the division | segmentation planned line of a sapphire wafer. For this reason, the cutting amount of a sapphire wafer can be reduced compared with the structure which cuts continuously in the state which cut the sapphire wafer. Therefore, frictional heat generated in the cutting blade during cutting of the sapphire wafer can be suppressed, and abnormal wear of the cutting blade can be prevented. Thus, a sapphire wafer with high hardness can be processed satisfactorily. Moreover, a sapphire wafer can be cut by blade dicing of a cutting device that is less expensive than a laser irradiation device.

  According to the present invention, by cutting the sapphire wafer intermittently along the planned division line of the sapphire wafer with the cutting blade, the sapphire wafer is improved while preventing abnormal wear of the cutting blade and a decrease in device productivity. Can be processed.

It is a perspective view of the cutting device concerning this embodiment. It is explanatory drawing of the cutting trace formation method which concerns on this Embodiment. It is explanatory drawing of the cutting trace formation process which concerns on this Embodiment. It is explanatory drawing of the division | segmentation process which concerns on this Embodiment.

  Hereinafter, a method for processing a sapphire wafer according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a cutting apparatus according to the present embodiment. FIG. 2 is an explanatory diagram of the cutting trace forming method according to the present embodiment. The present invention can be applied to any cutting device as long as it uses a cutting blade to form a cutting trace along a line to be divided of a sapphire wafer.

  As shown in FIG. 1, the cutting apparatus 1 is configured to cut the sapphire wafer W by relatively moving the cutting means 3 having the cutting blade 31 and the chuck table 2 holding the sapphire wafer W. The sapphire wafer W is formed in a disk shape, and a plurality of division lines are arranged on the surface 61 of the sapphire wafer W. In the center of the surface of the sapphire wafer W, a device 66 is formed in each region defined by the division lines.

  The sapphire wafer W is carried into the cutting apparatus 1 while being supported by the annular frame 69 via the sticking tape 68. On the base 11 of the cutting apparatus 1, a cutting feed means 4 for cutting and feeding the chuck table 2 in the X-axis direction is provided. Further, on the base 11, a gate-shaped column portion 12 erected so as to straddle the cutting feed means 4 is provided. The column part 12 is provided with an indexing feeding means 5 for indexing and feeding the pair of cutting means 3 in the Y-axis direction and raising and lowering in the Z-axis direction above the chuck table 2.

  The cutting feed means 4 has a pair of guide rails 41 arranged on the upper surface of the base 11 and parallel to the X-axis direction, and a motor-driven X-axis table 42 slidably installed on the pair of guide rails 41. doing. On the X-axis table 42, the chuck table 2 is rotatably supported by the θ table 43. A nut portion (not shown) is formed on the back side of the X-axis table 42, and a ball screw 44 is screwed to the nut portion. A drive motor 45 is connected to one end of the ball screw 44. The ball screw 44 is rotationally driven by the drive motor 45, and the chuck table 2 is moved along the guide rail 41 in the X-axis direction.

  The chuck table 2 is provided on a θ table 43 that can rotate about the Z-axis. On the surface of the chuck table 2, a holding surface 21 for sucking and holding the sapphire wafer W by a porous ceramic material is formed. The holding surface 21 is connected to a suction source through a flow path in the chuck table 2. Further, around the chuck table 2, four clamp portions 22 are provided via a pair of support arms extending outward from the four sides of the θ table 43. The four clamp portions 22 are driven by an air actuator to sandwich and fix the annular frame 69 around the sapphire wafer W.

  The indexing and feeding means 5 has a pair of guide rails 51 parallel to the Y-axis direction with respect to the front surface of the column portion 12 and a pair of motor-driven Y-axis tables 52 slidably installed on the pair of guide rails 51. doing. The index feeding means 5 includes a pair of guide rails 53 arranged in front of each Y-axis table 52 and parallel to the Z-axis direction, and a motor-driven Z-axis table 54 slidably installed on each guide rail 53. And have. A cutting means 3 for cutting the sapphire wafer W by cutting the cutting blade 31 is provided below each Z-axis table 54.

  A nut portion (not shown) is formed on the back side of each Y-axis table 52, and a ball screw 55 is screwed to the nut portion. Further, nut portions (not shown) are formed on the back side of each Z-axis table 54, and a ball screw 56 is screwed to these nut portions. Drive motors 57 and 58 are connected to one end of a ball screw 55 for the Y-axis table 52 and a ball screw 56 for the Z-axis table 54, respectively. The ball screws are rotationally driven by these drive motors 57 and 58, and the pair of cutting means 3 are moved along the guide rails 51 and 53 in the Y-axis direction and the Z-axis direction.

  The cutting blade 31 of the cutting means 3 is provided at the tip of a spindle (not shown) that rotates about the Y axis. The cutting blade 31 is composed of a resin blade in which diamond abrasive grains are hardened with a resin bond to form a circle. The cutting blade 31 is covered with a blade cover 34, and the blade cover 34 is provided with an injection nozzle for injecting cutting water toward the cutting portion. The cutting means 3 rotates the cutting blade 31 at a high speed and cuts the sapphire wafer W while spraying cutting water from a plurality of spray nozzles onto the cutting portion.

  In the cutting apparatus 1 configured as described above, the sapphire wafer W is held on the chuck table 2 so that the center of the sapphire wafer W coincides with the rotation axis of the chuck table 2 (see FIG. 3A). The cutting blade 31 is positioned on the planned division line of the sapphire wafer W. Then, the cutting blade 31 is rotated at a high speed, the cutting blade 31 is lowered, and a division planned line of the sapphire wafer W is cut from the upper surface side of the sapphire wafer W.

  When the sapphire wafer W is cut by the cutting blade 31, the chuck table 2 is not cut and fed, and the cutting blade 31 is raised and separated from the sapphire wafer W. Thereby, the cutting trace 63 (refer FIG. 2) is formed on the division | segmentation planned line of the sapphire wafer W. FIG. Then, with the cutting blade 31 separated from the sapphire wafer W, the chuck table 2 is moved by a predetermined pitch in the X-axis direction and stopped. A plurality of cutting marks 63 are formed on the division line of the sapphire wafer W by alternately raising and lowering the cutting blade 31 and intermittent movement of the chuck table 2.

  Specifically, as shown in FIG. 2A, cutting traces 63 are formed at predetermined pitches P on the planned division line of the sapphire wafer W. For example, when the cutting blade 31 having a diameter of 52 mm is used, the predetermined pitch P is set to 3.0 mm. Since the predetermined pitch P is adjusted to an interval at which both ends of the adjacent cutting traces 63 overlap each other, a plurality of cutting traces 63 are formed in a straight line along the planned division line of the sapphire wafer W. In this way, by cutting the sapphire wafer W only by cutting in the thickness direction, so-called chopper cutting, the intermittent cutting operation is repeated to make the cutting traces 63 continuous, so that one sapphire wafer W is divided into the division lines. Grooves are formed.

  For this reason, the cutting amount of the sapphire wafer W to be continuously cut can be reduced as compared with a so-called chopper traverse cut in which the sapphire wafer W is cut and fed. Thereby, frictional heat generated in the cutting blade 31 during cutting of the sapphire wafer W is suppressed, and abnormal wear of the cutting blade 31 is prevented.

  In the present embodiment, as shown in FIG. 2A, both ends of adjacent cutting marks 63 are formed so as to overlap each other, but the present invention is not limited to this configuration. For example, as shown in FIG. 2B, the predetermined pitch P may be set so that both ends of the adjacent cutting marks 63 are in contact with each other on the surface 61 of the sapphire wafer W. For example, when the cutting blade 31 having a diameter of 52 mm is used, the predetermined pitch P is set to 5.6 mm. Further, as shown in FIG. 2C, a predetermined pitch P may be set so that a plurality of cutting marks 63 are formed at regular intervals on the surface 61 of the sapphire wafer W. For example, when the cutting blade 31 having a diameter of 52 mm is used, the predetermined pitch P is set to 7.0 mm.

  In the cutting process shown in FIG. 2A, a plurality of cutting marks 63 are formed with a smaller pitch P than the cutting process shown in FIGS. 2B and 2C. Therefore, in the cutting process shown in FIG. 2A, the strength of the division planned line is lowered and the division accuracy is increased as compared with the cutting process shown in FIGS. 2B and 2C. In the cutting process shown in FIG. 2B, a plurality of cutting marks 63 are formed with a pitch P larger than that shown in FIG. 2A and with a smaller pitch P than that shown in FIG. 2C. For this reason, the cutting shown in FIG. 2B can reduce the number of times of cutting as compared with the cutting shown in FIG. 2A, and the strength of the division planned line is reduced and the division accuracy is increased as compared with the cutting shown in FIG. 2C. Yes. In the cutting process shown in FIG. 2C, a plurality of cutting marks 63 are formed with a larger pitch P than the cutting process shown in FIGS. 2A and 2B. For this reason, the cutting shown in FIG. 2C can reduce the number of times of cutting compared to the cutting shown in FIGS. 2B and 2C.

  With reference to FIG.3 and FIG.4, the flow of the processing method of the sapphire wafer which concerns on this Embodiment is demonstrated. FIG. 3 is an explanatory diagram of a cutting mark forming step according to the present embodiment. FIG. 4 is an explanatory diagram of the dividing step according to the present embodiment. Here, a braking device is used in the dividing step, but a tape expansion device can also be used in the dividing step.

  As shown in FIG. 3A, a holding step is first performed. In the holding step, the back surface 62 of the sapphire wafer W is held on the holding surface 21 of the chuck table 2 via the sticking tape 68. As shown in FIG. 3B, the positioning step is performed after the holding step. In the positioning step, the cutting blade 31 is positioned on the division planned line of the sapphire wafer W.

  As shown in FIG. 3C, after the positioning process is performed, a cutting mark forming process is performed. In the cutting trace forming step, the cutting blade 31 descends while rotating at high speed, and the sapphire wafer W is cut. Then, the cutting blade 31 rises without the chuck table 2 being cut and a cutting mark 63 is formed along the planned division line of the sapphire wafer W. Subsequently, the chuck table 2 is cut and fed by a predetermined pitch P with the cutting blade 31 raised, and the unprocessed portion of the sapphire wafer W is positioned below the cutting blade 31.

  As shown in FIG. 3D, by repeating this series of operations, a plurality of cutting marks 63 are continuously formed along the planned division line of the sapphire wafer W. At this time, the subsequent cutting trace 63 is formed on the sapphire wafer W so as to overlap the end of the previously formed cutting trace 63. The bottom surface 64 of each cutting mark 63 has an arc shape when viewed from the side, and the end of the bottom surface 64 of the cutting mark 63 positioned in front is cut when the subsequent cutting mark 63 is formed. For this reason, the continuous straight groove | channel on the division | segmentation scheduled line of the sapphire wafer W is formed by making the some cutting trace 63 continue.

  In the cutting trace forming step, the cutting operation for cutting only by raising and lowering the cutting blade 31 is repeated, so that the planned dividing line of the sapphire wafer W is intermittently cut. Thereby, the continuous machining time of each cutting operation is shortened, and a cooling period is provided after the cutting operation is completed and the next cutting operation is started. Therefore, frictional heat generated in the cutting blade 31 when cutting the sapphire wafer W is suppressed, and abnormal wear of the cutting blade 31 is prevented.

In addition, an example of the processing conditions in this cutting trace formation process is as showing below.
Blade type: Resin blade spindle with outer diameter 52 mm, blade thickness 0.1 mm: 4000 rpm
Z feed rate: 0.1 mm / s
Cutting depth: 150 μm
Chuck table X feed pitch: 3mm
Sapphire wafer thickness: 300 μm
When the cutting traces 63 are formed along all the planned division lines of the sapphire wafer W, they are carried into the braking device 7 (see FIG. 4).

  As shown to FIG. 4A, after implementing a cutting trace formation process, a division | segmentation process is implemented. In the dividing step, the sapphire wafer W is placed on the pair of support portions 71 with the surface 61 facing downward. The pair of support portions 71 extend in one direction (the Y-axis direction in FIG. 4), and an imaging unit 73 is disposed between the pair of support portions 71. The imaging means 73 images the surface 61 of the sapphire wafer W from between the pair of support portions 71. A pressing blade 72 that presses the sapphire wafer W from above is provided above the pair of support portions 71 with the sapphire wafer W interposed therebetween. The pressing blade 72 extends in one direction (Y-axis direction in FIG. 4) and is moved up and down by a pressing mechanism (not shown).

  When the surface of the sapphire wafer W is imaged by the imaging unit 73, the cutting mark 63 (division line) is positioned between the pair of support portions 71 and immediately below the pressing blade 72 based on the captured image. As shown in FIG. 4B, the sapphire wafer W is divided by using the cutting marks 63 as the division starting point by lowering the pressing blade 72. The sapphire wafer W is divided into individual device chips by pressing the pressing blade 72 against all the division lines.

  As described above, according to the method for processing the sapphire wafer W according to the present embodiment, the cutting operation of cutting only by raising and lowering the cutting blade 31 is repeated intermittently along the planned division line of the sapphire wafer W. A continuous cutting mark 63 is formed. For this reason, compared with the structure cut continuously in the state which cut the sapphire wafer W, the cutting amount which cuts the sapphire wafer W continuously can be reduced. Therefore, the frictional heat generated in the cutting blade 31 when cutting the sapphire wafer W can be suppressed, and abnormal wear of the cutting blade 31 can be prevented. Thus, the sapphire wafer W having high hardness can be processed satisfactorily. Moreover, a sapphire wafer can be cut by blade dicing of a cutting device that is less expensive than a laser irradiation device.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above embodiment, a plurality of cutting marks 63 are formed by repeating chopper cuts that are cut only by the lifting and lowering operation of the cutting blade 31, but the present invention is not limited to this configuration. The plurality of cutting marks 63 may be formed by intermittently cutting the sapphire wafer W with the cutting blade 31. For example, the cutting blade 31 is lowered and cut into the sapphire wafer W, the sapphire wafer W is cut and fed by a minute distance so that the cutting blade 31 does not wear abnormally, and the cutting blade 31 is raised, and this intermittent chopper traverse. A plurality of cutting marks 63 may be formed by repeating the cutting.

  Moreover, in this Embodiment, although the cutting trace formation process is performed with a cutting device and the division | segmentation process is performed with a braking device, one part process or all processes may be performed with one apparatus.

  As described above, the present invention has an effect that a sapphire wafer can be satisfactorily processed while preventing abnormal wear of a cutting blade and a decrease in device productivity, and in particular, a sapphire wafer used for manufacturing a light emitting diode. It is useful for the processing method.

DESCRIPTION OF SYMBOLS 1 Cutting device 2 Chuck table 3 Cutting means 4 Cutting feed means 5 Index feed means 7 Breaking device 31 Cutting blade 61 Front surface of sapphire wafer 62 Back surface of sapphire wafer 63 Cutting trace W Sapphire wafer

Claims (1)

A sapphire wafer processing method for dividing a sapphire wafer into individual chips,
A chuck table for holding a sapphire wafer; a cutting means having a cutting blade for cutting the sapphire wafer held by the chuck table; a cutting feed means for relatively cutting and feeding the cutting means and the chuck table; In a cutting apparatus comprising a cutting means and an index feed means for relatively indexing and feeding the chuck table in a direction orthogonal to the cutting feed direction, the sapphire wafer is intermittently cut along the scheduled division line by the cutting blade. Cutting trace formation process to form a plurality of cutting traces,
After the cutting trace forming step, a dividing step of applying an external force along the planned division line of the sapphire wafer and dividing the sapphire wafer into individual chips along the planned dividing line from the plurality of cutting traces;
A processing method of sapphire wafer composed of

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