JP5603085B2 - Manufacturing method of optical device wafer - Google Patents

Description

  The present invention relates to a method for manufacturing an optical device wafer in which an optical device layer (epi layer) composed of an n-type nitride semiconductor layer and a p-type nitride semiconductor layer is laminated on the surface of a sapphire substrate.

  In an optical device manufacturing process, an optical device layer made of a gallium nitride compound semiconductor is laminated on the surface of a sapphire substrate having a substantially disc shape, and light emitting diodes are divided into a plurality of regions partitioned by a plurality of streets formed in a lattice shape. Then, an optical device such as a laser diode is formed to constitute an optical device wafer. Then, the optical device wafer is cut along the streets to divide the region where the optical device is formed to manufacture individual optical devices. (For example, refer to Patent Document 1.)

  Further, in order to increase the light emission efficiency of the optical device, a technique for forming the surface of the p-type nitride semiconductor layer in an uneven shape has been proposed. (For example, see Patent Document 2.)

Japanese Patent No. 2859478 JP 2000-196152 A

  Thus, the technique described in Patent Document 2 described above is based on p-type nitridation using a lithography technique or a dry etching technique after an n-type nitride semiconductor layer and a p-type nitride semiconductor layer are stacked on the surface of a sapphire substrate. Since this is a method of forming the surface of the physical semiconductor layer in an uneven shape, there is a problem that productivity is low.

  The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is an optical device wafer manufacturing method capable of efficiently manufacturing an optical device wafer in which the surface of the optical device layer is formed in an uneven shape. Is to provide.

In order to solve the main technical problem, according to the present invention, an optical device wafer manufacturing method in which an optical device layer is laminated on the surface of a sapphire substrate,
An irregularity forming step of grinding the surface of the sapphire substrate to form an irregularity undulation having a wavelength half that of light emitted from the optical device on the surface of the sapphire substrate,
An optical device layer forming step in which the surface of the sapphire substrate subjected to the unevenness forming step is formed by laminating an optical device layer having an uneven surface following the undulation of the unevenness,
An optical device wafer manufacturing method is provided.

  The concavo-convex forming step includes holding the back surface side of the sapphire substrate on the holding surface of the chuck table of the grinding apparatus, rotating the grinding wheel while vibrating it, and bringing it into contact with the surface of the sapphire substrate. Are relatively moved in parallel with the holding surface of the chuck table, thereby forming fine undulations on the surface of the sapphire substrate.

In the method of manufacturing an optical device wafer according to the present invention, the surface of the sapphire substrate is ground to form an uneven wave having a wavelength half that of the light emitted from the optical device on the surface of the sapphire substrate. Since the optical device layer having an uneven surface is formed by following the uneven wave, the n-type nitride semiconductor layer and the p-type nitride layer are formed on the surface of the sapphire substrate as in the technique described in Patent Document 2 above. Compared with a method in which the surface of the p-type nitride semiconductor layer is formed in a concavo-convex shape by using a lithography technique or a dry etching technique after the physical semiconductor layer is laminated, it is efficient and productivity can be improved.

The perspective view of the sapphire substrate which comprises the optical device wafer manufactured by the manufacturing method of the optical device wafer by this invention. The perspective view of the grinding apparatus for implementing the uneven | corrugated formation process in the manufacturing method of the optical device wafer by this invention. Sectional drawing of the spindle unit which comprises the grinding unit of the grinding apparatus shown in FIG. Explanatory drawing of the protective tape sticking process which sticks a protective tape on the back surface of the sapphire substrate shown in FIG. Explanatory drawing of the uneven | corrugated formation process in the manufacturing method of the optical device wafer by this invention. The top view and principal part expanded sectional view of the sapphire substrate in which the uneven | corrugated formation process in the manufacturing method of the optical device wafer by this invention was implemented. The principal part expanded sectional view of the optical device wafer in which the optical device layer formation process in the manufacturing method of the optical device wafer by this invention was implemented.

DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of an optical device manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a circular sapphire substrate 10 for forming an optical device wafer. The sapphire substrate 10 is formed with a thickness of 480 μm, for example.

  The sapphire substrate 10 shown in FIG. 1 is first subjected to a concavo-convex forming step in which the surface 10 a is ground to form fine undulations on the surface 10 a of the sapphire substrate 10. This uneven | corrugated formation process is implemented using the grinding apparatus shown in FIG. The grinding device 2 shown in FIG. 2 includes a device housing generally designated by numeral 20. The device housing 20 includes a rectangular parallelepiped main portion 21 that extends elongated and an upright wall 22 that is provided at a rear end portion (upper right end in FIG. 1) of the main portion 21 and extends in the vertical direction. A pair of guide rails 221 and 221 extending in the vertical direction are provided on the front surface of the upright wall 22. A grinding unit 3 as grinding means is mounted on the pair of guide rails 221 and 221 so as to be movable in the vertical direction.

  The grinding unit 3 includes a moving base 31 and a spindle unit 32 attached to the moving base 31. The movable base 31 is provided with a pair of legs 311 and 311 extending in the vertical direction on both sides of the rear surface. The pair of legs 311 and 311 is slidably engaged with the pair of guide rails 221 and 221. Guided grooves 312 and 312 are formed. As described above, a support portion 313 protruding forward is provided on the front surface of the movable base 31 slidably mounted on the pair of guide rails 221 and 221 provided on the upright wall 22. The spindle unit 32 is attached to the support portion 313.

  The spindle unit 32 includes a spindle housing 321 mounted on the support portion 313 and a rotating spindle 322 that is rotatably disposed on the spindle housing 321. The spindle unit 32 will be described with reference to FIG. A spindle housing 321 constituting the spindle unit 32 shown in FIG. 3 is formed in a substantially cylindrical shape and includes a shaft hole 321a penetrating in the axial direction. A rotary spindle 322 that is inserted through a shaft hole 321a formed in the spindle housing 321 is provided with a thrust bearing flange 322a that protrudes in the radial direction at the center. In this way, the rotary spindle 322 inserted through the shaft hole 321a formed in the spindle housing 321 is rotatably supported by high-pressure air supplied between the inner wall of the shaft hole 321a. One end (lower end in FIG. 3) of the rotary spindle 322 rotatably supported by the spindle housing 321 is disposed so as to protrude from the lower end of the spindle housing 321, and a wheel mount is mounted on one end (lower end in FIG. 3). 33 is provided. A grinding wheel 34 is attached to the lower surface of the wheel mount 33.

  The grinding wheel 34 includes an annular wheel base 341 and a plurality of grinding wheels 342 mounted on the lower surface of the wheel base 341. The wheel base 341 includes an annular mounting portion 341a that forms an inner peripheral portion and is connected to the wheel mount 33, and an annular grindstone mounting portion 341b that surrounds the annular mounting portion 341a and forms an outer peripheral portion. Yes. The attachment portion 341a is detachably attached to the wheel mount 33 by the fastening bolt 35. The annular grindstone mounting portion 341b is formed with a step below the upper surface of the mounting portion 341a, and a plurality of grinding wheels 342 are mounted on the lower surface of the annular grindstone mounting portion 341b with an appropriate adhesive in the circumferential direction. Has been. An annular vibrator 37 that applies vibration to the plurality of grinding wheels 342 is mounted on the upper surface of the grinding wheel mounting portion 341b with an appropriate adhesive. The vibrator 37 is formed of piezoelectric ceramics such as barium titanate, lead zirconate titanate, and lithium tantalate. The vibrator 37 mounted on the upper surface of the grindstone mounting portion 341b in this way is connected to a power supply unit described later.

  The spindle unit 32 in the illustrated embodiment includes an electric motor 38 for driving the rotary spindle 322 to rotate. The illustrated electric motor 38 is a permanent magnet motor. The permanent magnet type electric motor 38 is arranged in a spindle housing 321 on the outer peripheral side of the rotor 381 and a rotor 381 made of a permanent magnet mounted on a motor mounting portion 322b formed in an intermediate portion of the rotary spindle 322. It consists of a stator coil 382. In the electric motor 38 configured as described above, the rotor 381 is rotated by applying AC power to the stator coil 382 by power supply means described later, and the rotating spindle 322 to which the rotor 381 is mounted is rotated.

  The spindle unit 32 in the illustrated embodiment includes power supply means 4 that applies AC power to the vibrator 37 and applies AC power to the electric motor 38. The power supply means 4 includes a rotary transformer 40 disposed at the rear end of the spindle unit 32. The rotary transformer 40 includes a power receiving unit 41 disposed at the rear end of the rotary spindle 322 and a power feeding unit 42 disposed opposite to the power receiving unit 41 and disposed at the rear end portion of the spindle housing 321. doing. The power receiving means 41 includes a rotor side core 411 mounted on the rotary spindle 322 and a power receiving coil 412 wound around the rotor side core 411. A conductive wire 413 is connected to the power receiving coil 412 of the power receiving means 41 configured as described above. The conductive wire 413 is disposed in a hole 322 c formed in the axial direction at the center of the rotary spindle 322, and the tip thereof is connected to the vibrator 37. The power feeding means 42 includes a stator side core 421 disposed on the outer peripheral side of the power receiving means 41 and a power feeding coil 422 disposed on the stator side core 421. The power feeding coil 422 of the power feeding means 42 configured in this way is supplied with AC power via the electric wiring 43.

  The power supply means 4 in the illustrated embodiment includes an AC power supply 44 for AC power supplied to the power supply coil 422 of the rotary transformer 40, a voltage adjustment means 45 as power adjustment means, and AC power supplied to the power supply means 42. Frequency adjusting means 46 for adjusting the frequency of the power, control means 47 for controlling the voltage adjusting means 45 and the frequency adjusting means 46, and input means for inputting the amplitude of vibration applied to the plurality of grinding wheels 342 to the control means 47. 48. The power supply means 4 shown in FIG. 3 supplies AC power to the stator coil 382 of the electric motor 38 via the control circuit 49 and the electric wiring 383.

The spindle unit 32 in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
When performing the grinding operation, AC power is supplied from the power supply means 4 to the stator coil 382 of the electric motor 38. As a result, the electric motor 38 rotates and the rotary spindle 322 rotates, and the grinding wheel 34 attached to the tip of the rotary spindle 322 is rotated.

  On the other hand, the power supply unit 4 controls the voltage adjusting unit 45 and the frequency converting unit 46 by the control unit 47 to control the voltage of the AC power to a predetermined voltage (for example, 20V) and the frequency of the AC power to the predetermined frequency. (E.g., 10 kHz) and supplied to the power supply coil 422 of the power supply means 42 constituting the rotary transformer 40. When AC power having a predetermined frequency is applied to the feeding coil 822 as described above, AC power having a predetermined frequency is applied to the vibrator 37 via the power receiving coil 412 and the conductive wire 413 of the rotating power receiving means 81. As a result, the vibrator 37 vibrates by being repeatedly displaced in the radial direction and the axial direction. This vibration is transmitted to the plurality of grinding wheels 342 via the wheel mounting portion 341b of the wheel base 341, and the plurality of grinding wheels 342 vibrate in the radial direction and the axial direction.

  Referring back to FIG. 2, the grinding apparatus 2 in the illustrated embodiment moves the polishing unit 32 in the vertical direction along the pair of guide rails 221 and 221 (perpendicular to the holding surface of the chuck table described later). A grinding unit feed mechanism 5 that moves in a specific direction. The polishing unit feed mechanism 5 includes a male screw rod 51 disposed on the front side of the upright wall 22 and extending in the vertical direction. The male screw rod 51 is rotatably supported by bearing members 52 and 53 whose upper end and lower end are attached to the upright wall 22. The upper bearing member 52 is provided with a pulse motor 54 as a drive source for rotationally driving the male screw rod 51, and an output shaft of the pulse motor 54 is transmission-coupled to the male screw rod 51. A connecting portion (not shown) that protrudes rearward from the center portion in the width direction is also formed on the rear surface of the movable base 31, and a through female screw hole (not shown) that extends in the vertical direction is formed in this connecting portion. The male screw rod 51 is screwed into the female screw hole. Accordingly, when the pulse motor 54 rotates in the forward direction, the moving base 31, that is, the polishing unit 3 is lowered or moved forward, and when the pulse motor 54 rotates in the reverse direction, the moving base 31, that is, the polishing unit 3 is raised or moved backward.

  Continuing the description with reference to FIG. 1, the chuck table mechanism 6 is disposed in the main portion 21 of the housing 20. The chuck table mechanism 6 includes a chuck table 61, a cover member 62 that covers the periphery of the chuck table 61, and bellows means 63 and 64 disposed before and after the cover member 62. The chuck table 61 is configured to suck and hold a wafer, which is a workpiece, on its upper surface by operating suction means (not shown). Further, the chuck table 61 is moved between a workpiece placement area A shown in FIG. 2 and a grinding area B by the grinding wheel 34 constituting the spindle unit 42 by a chuck table moving means (not shown). The bellows means 63 and 64 can be formed from any suitable material such as campus cloth. The front end of the bellows means 63 is fixed to the front wall of the main portion 21, and the rear end is fixed to the front end surface of the cover member 62. The front end of the bellows means 64 is fixed to the rear end surface of the cover member 62, and the rear end is fixed to the front surface of the upright wall 22 of the apparatus housing 20. When the chuck table 61 is moved in the direction indicated by the arrow 61a, the bellows means 63 is expanded and the bellows means 64 is contracted. When the chuck table 61 is moved in the direction indicated by the arrow 61b, the bellows means 63 is The bellows means 64 is expanded by contraction.

  In order to carry out the unevenness forming step using the grinding device 2 described above, a protective tape T is attached to the back surface 10b of the sapphire substrate 10 as shown in FIG. 4 (protective tape attaching step). Thus, the protective tape T side of the sapphire substrate 10 to which the protective tape T is adhered is placed on the upper surface (holding surface) of the chuck table 61 positioned in the workpiece placement area A of the grinding device 2. Then, the sapphire substrate 10 is sucked and held on the chuck table 61 via the protective tape T by suction means (not shown) (sapphire substrate holding step). Therefore, the surface 10a of the sapphire substrate 10 held on the chuck table 61 is on the upper side. When the sapphire substrate 10 is sucked and held on the chuck table 61 in this way, the chuck table 61 is moved to the grinding zone B and positioned at the grinding start position as shown in FIG. Next, the grinding wheel 34 is ground and fed downward to a predetermined grinding position (for example, a position 30 μm below the surface of the sapphire substrate 10) while rotating at 1000 rpm, for example, in the direction indicated by the arrow 34a in FIG. As described above, for example, by applying AC power of 10 kHz to the vibrator 37, the plurality of grinding wheels 342 constituting the grinding wheel 34 are vibrated at a frequency of 10 kHz. Then, the chuck table 61 is processed and fed in the direction indicated by the arrow 61a at a processing feed rate of 3 mm / second, for example, and moved to the grinding end position indicated by a two-dot chain line in FIG. The grinding end position is set to a predetermined position where the left end of the sapphire substrate 10 passes through the grinding surface which is the lower surface of the grinding wheel 342. As a result, the surface 10a of the sapphire substrate 10 held by the chuck table 61 is ground by the grinding surface of the grinding wheel 342 acting from one end (right end) to the other end (left end). As a result, on the surface 10a of the sapphire substrate 10 held on the chuck table 61, a fine undulation 100 is formed as shown in FIGS. 6 (a) and 6 (b). In addition, the wavelength (S) of the uneven | corrugated wave | undulation 100 formed in the surface 10a of the sapphire substrate 10 by the said process conditions will be 300 nm. For example, it is said that the light emission efficiency can be further improved by forming a concavo-convex wave having a half of the wavelength of light emitted from the optical device in the optical device layer. Therefore, an optical device that emits light having a wavelength of 600 nm. Is manufactured, it is desirable to grind the surface 10a of the sapphire substrate 10 under the processing conditions described above.

  If the uneven | corrugated formation process mentioned above is implemented, the optical device layer formation process which laminates | stacks and forms an optical device layer on the surface 10a of the sapphire substrate 10 will be implemented. That is, as shown in FIG. 7, an n-type nitride semiconductor layer 111 is stacked on the surface 10a of the sapphire substrate 10 by epitaxial growth, and a p-type nitride semiconductor layer 112 is stacked on the surface of the n-type nitride semiconductor layer 111 by epitaxial growth. Thus, the optical device layer 11 is formed. As a result, the optical device wafer 1 in which the optical device layer 11 composed of the n-type nitride semiconductor layer 111 and the p-type nitride semiconductor layer 112 is formed on the surface 10a of the sapphire substrate 10 is obtained. As described above, the n-type nitride semiconductor layer 111 and the p-type nitride semiconductor layer 112 constituting the optical device layer 11 formed on the surface 10 a of the sapphire substrate 10 are undulations formed on the surface 10 a of the sapphire substrate 10. Therefore, the surface of the optical device layer 11 has undulations.

  In the optical device wafer manufacturing method described above, the surface 10a of the sapphire substrate 10 is ground to form fine irregularities 100 on the surface 10a of the sapphire substrate 20, and the n-type nitride follows the irregularities 100. Since the semiconductor layer 111 and the p-type nitride semiconductor layer 112 are stacked, the n-type nitride semiconductor layer and the p-type nitride semiconductor layer are stacked on the surface of the sapphire substrate as in the technique described in Patent Document 2 above. Compared with a method of forming the surface of the p-type nitride semiconductor layer in a concavo-convex shape using a lithography technique or a dry etching technique, it is efficient and productivity can be improved.

1: Optical device wafer 10: Sapphire substrate 11: Optical device layer (epi layer)
111: n-type nitride semiconductor layer 112: p-type nitride semiconductor layer 2: grinding device 3: grinding unit 32: spindle unit 34: grinding wheel 342: grinding wheel 37: vibrator 4: power supply means 6: chuck table mechanism 61: Chuck table
T: Protective tape

Claims (2)

An optical device wafer manufacturing method in which an optical device layer is laminated on the surface of a sapphire substrate,
An irregularity forming step of grinding the surface of the sapphire substrate to form an irregularity undulation having a wavelength half that of light emitted from the optical device on the surface of the sapphire substrate,
An optical device layer forming step in which the surface of the sapphire substrate subjected to the unevenness forming step is formed by laminating an optical device layer having an uneven surface following the undulation of the unevenness,
An optical device wafer manufacturing method characterized by the above. The concavo-convex forming step includes holding the back surface side of the sapphire substrate on the holding surface of the chuck table of the grinding apparatus, rotating the grinding wheel while vibrating it, and bringing it into contact with the surface of the sapphire substrate. 2 is formed on the surface of the sapphire substrate to form a concavo-convex undulation having a wavelength half that of the light emitted from the optical device. Optical device wafer manufacturing method.

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