JP2011224925A - Tool for forming uneven structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool that can easily form an uneven structure on a warped substrate.SOLUTION: There is provided the tool 62 for forming the uneven structure 64 on a liquid resin 76 covered over a top surface of a workpiece 70. The tool includes: a circular recessed part formed in the center; an annular projection 58 surrounding the circular recessed part; and the uneven structure 64 formed on a rear surface of the circular recessed part.

Description

  The present invention relates to a jig for forming a desired uneven structure on a workpiece.

  For example, in a manufacturing process of a light emitting device such as an LED (Light Emitting Diode) or an LD (Laser Diode), a plurality of light emitting devices are formed by stacking semiconductor layers on a substrate, and then the substrate is divided into individual pieces. Thus, individual light emitting devices are manufactured.

  In particular, sapphire is used as a substrate in a gallium nitride optical device that emits green or blue light, and an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer are sequentially formed on the sapphire substrate. A light-emitting device is formed by providing an n-electrode or a p-electrode for applying voltage to each of the semiconductor layers.

  In these light emitting devices, it is very important to efficiently extract light generated in the light emitting layer to the outside. Therefore, for light traveling upward from the light-emitting layer, a reflective layer is provided for the form in which the p-electrode, which is the upper electrode, is used as a transparent electrode so as not to be an obstacle to the outside, Various measures are taken, such as a form of reflecting upward.

  On the other hand, light propagating laterally from the light emitting layer accounts for a large part of the total amount of light generated in the light emitting layer, and may reach 60% of the total. Therefore, in order to efficiently extract the light propagating in the lateral direction from the upper side of the device to the outside, for example, in Japanese Patent Application Laid-Open No. 2002-280611 or Japanese Patent Application Laid-Open No. 2008-60286, the interface between the substrate and the n-type semiconductor layer is used. A method of forming a fine uneven structure on the side has been proposed.

  With this concavo-convex structure, a concavo-convex refractive index interface having a different refractive index is formed between the substrate and the n-type semiconductor layer, and the light propagating in the lateral direction generated in the light emitting layer is affected by the concavo-convex refractive index interface. Mode conversion occurs (the traveling direction of light is changed to the surface emission direction by irregular reflection), and the direction of the light travels in a direction other than the lateral direction. As a result, the amount of light traveling toward the extraction surface above the device is increased, and the light extraction efficiency is improved.

JP 2002-280611 A Japanese Patent Laid-Open No. 2008-60286

  As a method of forming a fine concavo-convex structure on a substrate, a method of forming by dry etching using a mask or anisotropic wet etching according to the material of the substrate is known. However, a substrate thinned to a predetermined thickness may be warped or wavy due to the thinning.

  In particular, when the substrate is made of a material that is difficult to process, such as sapphire or SiC, warping is likely to occur. Such a warped substrate has a problem that it is very difficult to form a mask following the warpage of the substrate and perform etching.

  The present invention has been made in view of these points, and an object thereof is to provide a jig for forming a concavo-convex structure capable of forming a desired concavo-convex structure even on a warped substrate. It is to be.

  According to the present invention, a jig for forming a concavo-convex structure in a liquid resin coated on the upper surface of a workpiece, a circular concave portion formed in the center, an annular convex portion surrounding the circular concave portion, And a concavo-convex structure formed on the back surface of the circular recess. A jig for forming the concavo-convex structure is provided.

  According to the present invention, by making the circular recess very thin, even a warped substrate can be placed on the substrate so as to follow the warp of the substrate. By providing an annular convex portion, the rigidity of the jig is improved and it is difficult to break.

It is a perspective view of a grinding device. It is a perspective view which shows the circular recessed part grinding method implemented with a grinding wheel. It is explanatory drawing of a circular recessed part grinding method. It is a perspective view of the jig | tool of this invention embodiment which has a circular recessed part and an annular convex part. It is a back side perspective view of the jig | tool shown in FIG. It is process drawing which shows the method of forming an uneven structure on the board | substrate with a curvature using the jig | tool of this invention. It is process drawing which shows the method of forming an uneven structure on the board | substrate with a curvature using the jig | tool of this invention (the 2).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a grinding apparatus 2 suitable for manufacturing the jig of the present invention. Reference numeral 4 denotes a base of the grinding apparatus 2, and a column 6 is erected on the rear side of the base 4. A pair of guide rails 8 extending in the vertical direction are fixed to the column 6.

  A grinding unit (grinding means) 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The grinding unit 10 includes a housing 12 and a support portion 14 that holds the housing 12, and the support portion 14 is attached to a moving base 16 that moves in the vertical direction along the pair of guide rails 8. .

  The grinding unit 10 includes a spindle 18 rotatably accommodated in a housing 12, a mounter 20 fixed to the tip of the spindle 18, and a plurality of grinding wheels that are screwed to the mounter 20 and arranged in an annular shape. A wheel 22 and a servomotor 26 that rotationally drives the spindle 18 are included.

  The grinding apparatus 2 includes a grinding unit moving mechanism 32 including a ball screw 28 that moves the grinding unit 10 in the vertical direction along the pair of guide rails 8 and a pulse motor 30. When the pulse motor 30 is driven, the ball screw 28 rotates and the moving base 16 is moved in the vertical direction.

  A recess 4a is formed on the upper surface of the base 4, and a chuck table mechanism 34 is disposed in the recess 4a. The chuck table mechanism 34 has a chuck table 36 and is moved in the Y-axis direction between a wafer attachment / detachment position A shown in FIG. 1 and a grinding position B facing the grinding unit 10 by a moving mechanism (not shown). 38 and 40 are bellows. On the front side of the base 4, an operation panel 42 on which an operator of the grinding apparatus 2 inputs grinding conditions and the like is disposed.

  The jig processing method according to the embodiment of the present invention in which a circular recess is formed in the center of the wafer and the annular protrusion surrounding the circular recess remains on the outer periphery by the grinding apparatus 2 configured as described above will be described below. explain.

  As a material for the jig, for example, a silicon wafer 11 cut out from a silicon ingot is used. The wafer 11 cut out from the silicon ingot has a thickness of 700 μm, for example.

  The silicon wafer 11 is placed on the chuck table 36 positioned at the wafer attachment / detachment position A shown in FIG. 1, and the wafer 11 is sucked and held by the chuck table 36. Next, the chuck table 36 is moved in the Y-axis direction and positioned at the grinding position B.

  2 and 3, while rotating the chuck table 36 in the direction indicated by the arrow 37 at 300 rpm, for example, the grinding wheel 22 having the grinding wheel 52 is rotated in the direction indicated by the arrow 53 at 6000 rpm, for example. Then, the grinding unit moving mechanism 32 is driven to bring the grinding wheel 52 into contact with the surface 11 a of the wafer 11. Then, the grinding wheel 22 is ground and fed downward by a predetermined amount at a predetermined grinding feed speed.

  Here, the relationship between the wafer 11 held on the chuck table 36 and the grinding wheel 52 constituting the grinding wheel 22 will be described with reference to FIG. The rotation center P1 of the chuck table 36 and the rotation center P2 of the grinding wheel 52 are eccentric. The grinding wheel 52 that is smaller than the diameter and larger than the radius of the boundary line 60 and arranged in an annular shape is set so as to pass through the rotation center P <b> 1 of the chuck table 36.

  As a result of grinding, as shown in FIG. 4, the central portion is ground and removed to form a circular recess 56 having a predetermined thickness (for example, 50 μm), and the outer peripheral side of the circular recess 56 remains on the surface 11 a of the wafer 11. As a result, an annular protrusion 58 is formed.

  Next, dry etching or anisotropic wet etching using a mask is performed on the back surface 11 b of the wafer 11 having the circular recess 56 on the front surface to form a fine concavo-convex structure 64. Alternatively, the fine concavo-convex structure 64 can be formed by machining or laser processing.

  The convex portion of the concavo-convex structure 64 can adopt a prismatic shape, a cylindrical shape, a truncated cone shape, or the like. The concavo-convex structure 64 may be a stripe shape or a dot shape, and may be arranged periodically or randomly. In this way, the uneven structure 64 is formed on the back surface 11 b to form the jig 62.

  Next, a method for forming a concavo-convex structure on a warped sapphire substrate using the jig 62 thus manufactured will be described with reference to FIGS. First, as shown in FIG. 6A, a liquid resin 74 that is cured by an external stimulus is dropped from a liquid resin supply device 72 onto a warped sapphire substrate 70, and a liquid resin layer 76 is formed on the sapphire substrate 70. Form.

  As the liquid resin 74 that is cured by an external stimulus, a thermosetting resin that is cured by heating is used in the present embodiment. However, the liquid resin 74 that is cured by an external stimulus is not limited to a thermosetting resin. For example, if the jig 62 or the sapphire substrate 70 is sufficiently thin and has a property of transmitting ultraviolet rays, An ultraviolet curable resin can be used as the liquid resin.

  Next, as shown in FIG. 6B, the jig 62 is pressed against the liquid resin layer 76 formed on the sapphire substrate 70 as indicated by the arrow A, and the jig 62 is pressed against the sapphire substrate 70. As shown in FIG. 6C, the liquid resin layer 76 is heated and cured by a halogen lamp heater 78.

  As a result, when the jig 62 is removed from the sapphire substrate 70, a resin mask 80 having an uneven structure corresponding to the uneven structure 64 of the jig 62 is formed on the sapphire substrate 70 as shown in FIG. be able to.

  Next, an etching solution such as hydrofluoric acid is supplied onto the resin mask 80 from the etching solution supply device, and isotropic etching is performed on the sapphire substrate 70 together with the resin mask 80 having a concavo-convex structure. Thereby, as shown in FIG. 7B, the concavo-convex structure 82 in which the concavo-convex structure 64 of the jig 62 is transferred onto the sapphire substrate 70 can be formed.

  Instead of wet etching, the resin mask 80 and the sapphire substrate 70 are isotropically etched by dry etching that supplies a fluorine-based stable gas in a plasma, and the concavo-convex structure 82 is formed on the sapphire substrate 70. Good.

  Since the circular recess 56 of the jig 62 of the present embodiment is formed very thin, when the jig 62 is pressed against the sapphire substrate 70, the warp of the sapphire substrate 70 is followed as shown in FIG. The jig 62 is deformed and the jig 62 adheres to the surface of the sapphire substrate 70 via the liquid resin layer 76.

  Therefore, the fine concavo-convex structure 82 can be formed on the warped sapphire substrate 70. Further, the jig 62 includes the annular convex portion 58, so that the rigidity of the jig is improved and the jig 62 is not easily damaged.

2 Grinding device 10 Grinding unit 11 Silicon wafer 22 Grinding wheel 56 Circular recess 58 Circular protrusion 62 Jig 64 Uneven structure 70 Sapphire substrate 76 Liquid resin layer 78 Halogen lamp heater 80 Resin mask 82 Uneven structure

Claims (1)

A jig for forming a concavo-convex structure in a liquid resin coated on the upper surface of a workpiece,
A circular recess formed in the center;
An annular convex portion surrounding the circular concave portion;
A concavo-convex structure formed on the back surface of the circular recess,
A jig for forming a concavo-convex structure characterized by comprising:

Images