JP2018046068A - Method for manufacturing light-emitting diode chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a light-emitting diode chip capable of obtaining sufficient luminance.SOLUTION: A method for manufacturing a light-emitting diode chip comprises the steps of: preparing a wafer which includes a laminate layer in which a plurality of semiconductor layers containing a light-emitting layer are formed on a transparent substrate for crystal growth, and in which an LED circuit 19 is formed in each of the regions partitioned by a plurality of division schedule lines mutually crossing a surface of the laminate layer; forming a plurality of recesses or grooves corresponding to each LED circuit on a rear surface of the wafer; forming a plurality of first dents corresponding to each LED circuit of the wafer on a surface of the transparent substrate in which a plurality of through holes are formed across the whole surface of the wafer; forming an integrated wafer by sticking the surface of the transparent substrate to the rear surface of the wafer; forming a plurality of second dents corresponding to each LED circuit of the wafer to a rear surface of the transparent substrate stuck to the rear surface of the wafer; and dividing the wafer into individual light-emitting diode chips by cutting the wafer together with the transparent substrate along the division schedule lines.SELECTED DRAWING: Figure 13

Description

  The present invention relates to a method for manufacturing a light-emitting diode chip.

  A stacked body layer in which a plurality of n-type semiconductor layers, light-emitting layers, and p-type semiconductor layers are stacked is formed on the surface of a crystal growth substrate such as a sapphire substrate, a GaN substrate, or a SiC substrate. A wafer in which a plurality of light emitting devices such as LEDs (Light Emitting Diodes) are formed in a region partitioned by the planned division line is cut along the planned division line and divided into individual light emitting device chips, and the divided light emission Device chips are widely used in various electric devices such as mobile phones, personal computers, and lighting devices.

  Since the light emitted from the light emitting layer of the light emitting device chip is isotropic, the light is emitted also to the inside of the crystal growth substrate, and the light is also emitted from the back and side surfaces of the substrate. However, of the light irradiated to the inside of the substrate, light whose incident angle at the interface with the air layer is greater than the critical angle is totally reflected at the interface and confined inside the substrate, and is not emitted outside from the substrate. Therefore, there is a problem that the luminance of the light emitting device chip is lowered.

  In order to solve this problem, a light emitting diode in which a transparent member is attached to the back surface of the substrate to improve the luminance in order to prevent light emitted from the light emitting layer from being confined inside the substrate. (LED) is described in Japanese Patent Application Laid-Open No. 2014-175354.

JP 2014-175354 A

  However, the light emitting diode disclosed in Patent Document 1 has a problem that sufficient luminance cannot be obtained although the luminance is slightly improved by sticking a transparent member to the back surface of the substrate.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a method of manufacturing a light-emitting diode chip capable of obtaining sufficient luminance.

  According to the present invention, there is provided a method for manufacturing a light-emitting diode chip, comprising: a stacked body layer in which a plurality of semiconductor layers including a light-emitting layer are formed on a transparent substrate for crystal growth; A wafer preparation step of preparing a wafer in which LED circuits are formed in each region partitioned by a plurality of intersecting division lines, and a plurality of recesses or grooves corresponding to each LED circuit are formed on the back surface of the wafer. A wafer back surface processing step, a first transparent substrate processing step of forming a plurality of first depressions corresponding to each LED circuit of the wafer on the surface of the transparent substrate having a plurality of through holes formed over the entire surface; An integration step of forming an integrated wafer by attaching the surface of the transparent substrate to the back surface of the wafer after the wafer back surface processing step and the first transparent substrate processing step; and And a second transparent substrate processing step of forming a plurality of second depressions corresponding to each LED circuit of the wafer on the back surface of the transparent substrate adhered to the back surface of the wafer, And dividing the integrated wafer into individual light-emitting diode chips by cutting the wafer together with the transparent substrate along the planned dividing line. A method for manufacturing a light-emitting diode chip is provided.

  Preferably, the cross-sectional shape of the first and second depressions formed in the first and second transparent substrate processing steps is any of a triangular shape, a square shape, or a circular shape. Preferably, in the wafer back surface processing step, the concave portion or the groove is formed by any one of a cutting blade, etching, sand blast, and laser, and in the first and second transparent substrate processing steps, the first and second The depression is formed by any one of etching, sand blasting, and laser.

  Preferably, the transparent substrate is formed of any one of transparent ceramics, optical glass, sapphire, and transparent resin, and in the integration step, the transparent substrate is bonded to the wafer with a transparent adhesive.

  The light-emitting diode chip manufactured by the method for manufacturing a light-emitting diode chip of the present invention has a recess or a groove formed on the back surface of the LED and has a plurality of through holes attached to the back surface. Since the depression is formed, in addition to increasing the surface area of the transparent member, the light irradiated from the light emitting layer of the LED and incident on the transparent member is refracted in a complicated manner at the depression, and the light emitted from the transparent member to the outside Since some of the refracted light is complicatedly refracted at the recessed portion, when light is emitted from the transparent member, the proportion of light whose incident angle at the interface between the transparent member and the air layer is greater than the critical angle is reduced and emitted from the transparent member The amount of light to be increased increases and the brightness of the light emitting diode chip is improved.

It is a surface side perspective view of an optical device wafer. FIG. 2A is a perspective view illustrating a wafer back surface processing step using a cutting blade, and FIGS. 2B to 2D are cross-sectional views illustrating the formed groove shape. 3A is a perspective view of the back surface side of the wafer having a plurality of grooves extending in the first direction formed on the back surface of the wafer, and FIG. 3B is a diagram illustrating the first direction formed on the back surface of the wafer and FIG. It is a back surface side perspective view of a wafer in which a plurality of grooves extended in the 2nd direction which intersects perpendicularly with the 1st direction were formed. 4A is a perspective view showing a state where a mask is attached to the back surface of the wafer, FIG. 4B is a perspective view of a state where a mask having a plurality of holes is attached to the back surface of the wafer, FIG. FIGS. 4C to 4E are partial perspective views of the wafer showing the shape of the recesses formed on the back surface of the wafer. 5A is a perspective view showing a state in which a groove is formed on the back surface of the wafer by a laser beam, FIG. 5B is a partial sectional view of the wafer showing the groove shape, and FIG. 5C is a sectional view of the wafer by the laser beam. FIG. 5 (D) is a partial perspective view of the wafer showing the formed circular recess. FIG. 6A is a perspective view showing a state in which a mask having a plurality of holes corresponding to each LED circuit of the optical device wafer is attached to the surface of a transparent substrate having a plurality of through-holes formed over the entire surface. (B) is a perspective view of a state in which a mask is attached to the surface of the transparent substrate, and FIGS. 6 (C) to 6 (E) are partial perspective views showing the shape of the recesses formed on the surface of the transparent substrate. FIG. 7A shows a first transparent substrate processing step for forming a plurality of depressions corresponding to each LED circuit of the optical device wafer on the surface of the transparent substrate in which a plurality of through holes are formed over the entire surface by laser beam irradiation. FIG. 7B is a partial perspective view showing the shape of the recess. FIG. 8A is a perspective view showing an integration process in which a transparent substrate having a plurality of depressions on the surface is attached to the back surface of the wafer and integrated, and FIG. 8B is a perspective view of the integrated wafer. FIG. 9A is a perspective view showing a second transparent substrate processing step for forming a plurality of depressions corresponding to each LED circuit of the optical device wafer by irradiation of a laser beam on the back surface of the transparent substrate constituting the integrated wafer, FIG. 9B is a cross-sectional view of an integrated wafer in which a transparent substrate having depressions formed on the front surface and the back surface of the transparent substrate is attached to the back surface of the wafer. It is a perspective view which shows the support process which supports an integrated wafer with a cyclic | annular flame | frame via a dicing tape. It is a perspective view which shows the division | segmentation process which divides | segments an integrated wafer into a light emitting diode chip. It is a perspective view of the integrated wafer after completion | finish of a division | segmentation process. 1 is a perspective view of a light emitting diode chip manufactured by a method of manufacturing a light emitting diode chip according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a front side perspective view of an optical device wafer 11 (hereinafter sometimes simply referred to as a wafer) 11.

  The optical device wafer 11 is configured by laminating an epitaxial layer (laminated body layer) 15 such as gallium nitride (GaN) on a sapphire substrate 13. The optical device wafer 11 has a front surface 11a on which an epitaxial layer 15 is stacked and a back surface 11b on which the sapphire substrate 13 is exposed.

  Here, in the optical device wafer 11 of the present embodiment, the sapphire substrate 13 is employed as the crystal growth substrate. However, a GaN substrate or a SiC substrate may be employed instead of the sapphire substrate 13.

  The stacked body layer (epitaxial layer) 15 includes an n-type semiconductor layer (for example, an n-type GaN layer) in which electrons are majority carriers, a semiconductor layer (for example, an InGaN layer) that is a light emitting layer, and a p in which holes are majority carriers. It is formed by epitaxially growing a type semiconductor layer (for example, a p-type GaN layer) in this order.

  The sapphire substrate 13 has a thickness of 100 μm, for example, and the laminate layer 15 has a thickness of 5 μm, for example. A plurality of LED circuits 19 are defined on the laminate layer 15 by a plurality of division lines 17 formed in a lattice pattern. The wafer 11 has a front surface 11a on which the LED circuit 19 is formed and a back surface 11b on which the sapphire substrate 13 is exposed.

  According to the light emitting diode chip manufacturing method of the embodiment of the present invention, first, a wafer preparation step for preparing an optical device wafer 11 as shown in FIG. 1 is performed. Further, a wafer back surface processing step for forming a plurality of grooves 3 corresponding to the LED circuits 19 on the back surface 11 b of the wafer 11 is performed.

  This wafer back surface processing step is performed using, for example, a well-known cutting device. As shown in FIG. 2A, the cutting unit 10 of the cutting apparatus includes a spindle housing 12, a spindle (not shown) rotatably inserted into the spindle housing 12, and a cutting blade 14 attached to the tip of the spindle. Is included.

  The cutting blade of the cutting blade 14 is formed of, for example, an electroforming grindstone in which diamond abrasive grains are fixed by nickel plating, and the tip shape thereof is triangular, quadrangular, or semicircular.

  The upper half of the cutting blade 14 is covered with a blade cover (wheel cover) 16, and the blade cover 16 is a pair of cooler nozzles (only one is shown) extending horizontally toward the back side and the near side of the cutting blade 14. 18 is arranged.

  In the wafer back surface processing step of forming a plurality of grooves 3 on the back surface 11b of the wafer 11, the surface 11a of the wafer 11 is sucked and held by a chuck table of a cutting device (not shown). Then, the cutting blade 14 is cut at a predetermined depth into the back surface 11b of the wafer 11 while rotating the cutting blade 14 at a high speed in the direction of arrow R, and the wafer 11 held on a chuck table (not shown) is processed and fed in the direction of arrow X1 to obtain the first direction. Grooves 3 that are elongated to each other are formed by cutting.

  As shown in FIG. 3 (A), the back surface 11b of the wafer 11 is cut while indexing and feeding the wafer 11 in the direction orthogonal to the arrow X1 direction by the pitch of the division line 17 of the wafer 11. A plurality of grooves 3 extending in succession are formed one after another.

  As shown in FIG. 3 (A), the plurality of grooves 3 formed on the back surface 11b of the wafer 11 may extend only in one direction, or as shown in FIG. A plurality of grooves 3 extending in the first direction and the second direction orthogonal to the first direction may be formed on the back surface 11 b of the wafer 11.

  The groove formed on the back surface 11b of the wafer 11 is a groove 3 having a triangular cross section as shown in FIG. 2 (B), or a groove 3A having a square cross section as shown in FIG. 2 (C), or FIG. 2 (D). Any of the grooves 3B having a semicircular cross section as shown in FIG.

  Instead of the embodiment in which the plurality of grooves 3, 3 </ b> A, 3 </ b> B are formed on the back surface 11 b of the wafer 11 by cutting, a plurality of recesses may be formed on the back surface 11 b of the wafer 11 corresponding to the LED circuit 19. In this embodiment, as shown in FIG. 4A, a mask 2 having a plurality of holes 4 corresponding to the LED circuit 19 of the wafer 11 is used.

  As shown in FIG. 4B, the holes 4 of the mask 2 are attached to the back surface 11 b of the wafer 11 so as to correspond to the LED circuits 19 of the wafer 11. Then, a triangular recess 5 corresponding to the shape of the hole 4 of the mask 2 is formed on the back surface 11b of the wafer 11 by wet etching or plasma etching, as shown in FIG.

  By changing the shape of the hole 4 of the mask 2 to a square shape or a circular shape, a rectangular recess 5A as shown in FIG. 4D is formed on the back surface 11b of the wafer 11, or FIG. A circular recess 5B may be formed on the back surface 11b of the wafer 11 as shown in FIG.

  As a modification of the present embodiment, a triangular recess as shown in FIG. 4C is formed on the back surface 11b of the wafer 11 by pasting the mask 2 on the back surface 11b of the wafer 11 and then performing sandblasting. 5 or a rectangular recess 5A as shown in FIG. 4D, or a circular recess 5B as shown in FIG. 4E.

  In order to form a plurality of grooves or a plurality of recesses corresponding to the LED circuit 19 on the back surface 11 b of the wafer 11, a laser processing apparatus may be used. In the first embodiment by laser processing, as shown in FIG. 5A, a laser beam having a wavelength (for example, 266 nm) having an absorptivity with respect to the wafer 11 is applied from the condenser (laser head) 24 to the wafer 11. A groove table 7 extending in the first direction is formed on the back surface 11b of the wafer 11 by ablation by processing and feeding a chuck table (not shown) holding the wafer 11 in the direction of the arrow X1 while irradiating the back surface 11b.

  A plurality of grooves 7 extending in the first direction are successively formed by ablating the back surface 11b of the wafer 11 while indexing and feeding the wafer 11 in the direction orthogonal to the arrow X1 direction by the pitch of the division lines 17 of the wafer 11. And form. The cross-sectional shape of the groove 7 may be a semicircular shape as shown in FIG. 5B, for example, or may be another shape.

  As an alternative embodiment, as shown in FIG. 5C, a pulse laser beam having a wavelength (for example, 266 nm) having an absorptivity is intermittently irradiated from the condenser 24 to the wafer 11 to You may make it form the some recessed part 9 corresponding to the LED circuit 19 in the back surface 11b. The shape of the recess 9 is usually a circle as shown in FIG. 5D corresponding to the spot shape of the laser beam.

  After performing the wafer back surface processing step or before performing, the LED circuit 19 corresponds to the surface 21a of the transparent substrate 21 in which a plurality of through holes 29 are formed over the entire surface to be adhered to the back surface 11b of the wafer 11. A first transparent substrate processing step for forming a plurality of depressions is performed.

  In this first transparent substrate processing step, for example, as shown in FIG. 6A, a mask 2 having a plurality of holes 4 corresponding to the LED circuit 19 of the wafer 11 is used. As shown in FIG. 6B, the holes 4 of the mask 2 are attached to the surface 21 a of the transparent substrate 21 so as to correspond to the LED circuits 19 of the wafer 11.

  Then, a triangular recess (recess) 35 corresponding to the shape of the hole 4 of the mask 2 is formed on the surface 21a of the transparent substrate 21 by wet etching or plasma etching, as shown in FIG.

  By changing the shape of the hole 4 of the mask 2 to a quadrangular shape or a circular shape, a rectangular recess 35A as shown in FIG. 6D is formed on the surface 21a of the transparent substrate 21, or FIG. A circular recess 35B may be formed on the surface 21a of the transparent substrate 21 as shown in FIG.

  The transparent substrate 21 is formed from any one of transparent resin, optical glass, sapphire, and transparent ceramics. In the present embodiment, the transparent substrate 21 is formed from a transparent resin such as polycarbonate or acrylic that is more durable than optical glass.

  As a modification of the present embodiment, the mask 2 is attached to the surface 21a of the transparent substrate 21, and then sandblasting is performed, so that the surface 21a of the transparent substrate 21 has a triangular shape as shown in FIG. Alternatively, a hollow 35A having a rectangular shape as shown in FIG. 6 (D) or a circular recess 35B as shown in FIG. 6 (E) may be formed.

  A laser processing apparatus may be used to form a plurality of depressions corresponding to the LED circuit 19 on the surface 21 a of the transparent substrate 21. In the embodiment by laser processing, as shown in FIG. 7A, a laser beam having a wavelength (for example, 266 nm) having an absorptivity with respect to the transparent substrate 21 is transmitted from the condenser (laser head) 24 to A plurality of depressions corresponding to the LED circuit 19 of the wafer 11 are formed on the surface 21a of the transparent substrate 21 by processing and feeding a chuck table (not shown) holding the transparent substrate 21 in the direction of the arrow X1 while intermittently irradiating the surface 21a. 39 is formed by ablation.

  The surface 21a of the transparent substrate 21 is ablated while indexing and feeding the transparent substrate 21 in the direction orthogonal to the arrow X1 direction by the pitch of the division lines 17 of the wafer 11, thereby forming a plurality of recesses 39 one after another. The cross-sectional shape of the recess 39 is usually a circle as shown in FIG. 7B corresponding to the spot shape of the laser beam.

  After performing the first transparent substrate processing step, an integration step is performed in which the front surface 21 a of the transparent substrate 21 is adhered to the back surface 11 b of the wafer 11 to form the integrated wafer 25. In this integration step, as shown in FIG. 8A, the back surface 11b of the wafer 11 is formed on the front surface 21a of the transparent substrate 21 in which a plurality of depressions 39 corresponding to the LED circuits 19 of the wafer 11 are formed on the front surface 21a. By bonding with a transparent adhesive, the wafer 11 and the transparent substrate 21 are integrated to form an integrated wafer 25 as shown in FIG.

  After performing the integration step, as shown in FIG. 9A, the wafer 11 side of the integrated wafer 25 is sucked and held by a chuck table (not shown), and has a wavelength that absorbs the transparent substrate 21 (for example, 266 nm) laser beam is intermittently radiated from the condenser 24 to the back surface 21b of the transparent substrate 21, and a chuck table (not shown) holding the integrated wafer 25 is processed and fed in the direction of the arrow X1. A second transparent substrate processing step is performed in which a plurality of recesses 9 corresponding to the LED circuits 19 of the wafer 11 are formed on the back surface 21b of the transparent substrate 21 constituting the substrate 25 by ablation.

  Referring to FIG. 9B, a partially enlarged cross-section of the integrated wafer 25 in which the depressions 39 are formed on the front surface 21a and the back surface 21b of the transparent substrate 21 by the first transparent substrate processing step and the second transparent substrate processing step. The figure is shown.

  After performing the second transparent substrate processing step, as shown in FIG. 10, the transparent substrate 21 of the integrated wafer 25 is attached to a dicing tape T whose outer peripheral portion is attached to the annular frame F, and the frame unit is attached. A support step is performed in which the integrated wafer 25 is supported by the annular frame F via the dicing tape T.

  After carrying out the supporting process, the frame unit is put into a cutting device, and the dividing step of cutting the integrated wafer 25 with the cutting device and dividing it into individual light emitting diode chips is carried out. This division step will be described with reference to FIG.

  In the dividing step, the integrated wafer 25 is sucked and held by the chuck table 20 of the cutting device via the dicing tape T of the frame unit, and the annular frame F is clamped and fixed by a clamp (not shown).

  Then, while rotating the cutting blade 14 in the direction of arrow R at high speed, the cutting blade 14 is cut into the division line 17 of the wafer 11 until the tip of the cutting blade 14 reaches the dicing tape T. From the cooler nozzle 18 to the processing point of the cutting blade 14 and the wafer 11. The cutting groove 27 for cutting the wafer 11 and the transparent substrate 21 is formed along the division line 17 of the wafer 11 by processing and feeding the integrated wafer 25 in the direction of the arrow X1 while supplying the cutting fluid.

  While indexing and feeding the cutting unit 10 in the Y-axis direction, similar cutting grooves 27 are formed one after another along the planned dividing line 17 extending in the first direction. Next, after the chuck table 20 is rotated by 90 °, similar cut grooves 27 are formed along all the planned dividing lines 17 extending in the second direction orthogonal to the first direction, as shown in FIG. In this state, the integrated wafer 25 is divided into light emitting diode chips 31 as shown in FIG.

  In the embodiment described above, the cutting device is used to divide the integrated wafer 25 into the individual light emitting diode chips 31. However, the laser beam having a wavelength that is transmissive to the wafer 11 and the transparent substrate 21 is divided. Irradiate the wafer 11 along the planned line 13 to form a plurality of modified layers in the thickness direction inside the wafer 11 and the transparent substrate 21, and then apply an external force to the integrated wafer 25 to modify the wafer. The integrated wafer 25 may be divided into individual light emitting diode chips 31 using the layers as division starting points.

  The light emitting diode chip 31 shown in FIG. 13 has a transparent member 21A in which a plurality of through holes 29 are formed on the back surface of an LED 13A having an LED circuit 19 on the front surface. Furthermore, depressions 35, 35A, 35B or depressions 39 are formed on the front and back surfaces of the transparent member 21A.

  Accordingly, in the light-emitting diode chip 31 shown in FIG. 13, since the recesses or grooves are formed on the back surface of the light-emitting diode and the recesses are formed on the front and back surfaces of the transparent member 21A, the surface area of the transparent member 21A increases. To do. Further, a part of the light emitted from the LED circuit 19 of the light emitting diode chip 31 and incident on the transparent member 21A is refracted in the recessed portion and then enters the transparent member 21A, and a part of the light emitted from the transparent member 21A is The light is emitted after being refracted in a complicated manner at the depression.

  Accordingly, when the light is refracted and emitted from the transparent member 21A, the ratio of the light whose incident angle at the interface between the transparent member 21A and the air layer is greater than the critical angle is reduced, and the light emitted from the transparent member 21A is reduced. The amount increases, and the luminance of the light emitting diode chip 31 is improved.

2 Mask 10 Cutting unit 11 Optical device wafer (wafer)
13 Sapphire substrate 14 Cutting blade 15 Laminate layer 17 Line to be divided 19 LED circuit 21 Transparent substrate 21A Transparent member 25 Integrated wafer 27 Cutting groove 29 Through hole 31 Light emitting diode chips 35, 35A, 35B, 39

Claims (4)

A method of manufacturing a light emitting diode chip,
Each of the regions has a laminate layer in which a plurality of semiconductor layers including a light emitting layer are formed on a transparent substrate for crystal growth, and is divided into a plurality of division lines intersecting each other on the surface of the laminate layer. A wafer preparation step of preparing a wafer on which an LED circuit is formed;
Wafer back surface processing step for forming a plurality of recesses or grooves corresponding to each LED circuit on the back surface of the wafer;
A first transparent substrate processing step of forming a plurality of first depressions corresponding to each LED circuit of the wafer on the surface of the transparent substrate having a plurality of through holes formed over the entire surface;
An integration step in which the wafer back surface processing step and the first transparent substrate processing step are performed, and then the surface of the transparent substrate is adhered to the back surface of the wafer to form an integrated wafer;
After performing the integration step, a second transparent substrate processing step of forming a plurality of second depressions corresponding to each LED circuit of the wafer on the back surface of the transparent substrate adhered to the back surface of the wafer When,
After performing the second transparent substrate processing step, a dividing step of cutting the wafer together with the transparent substrate along the division line to divide the integrated wafer into individual light emitting diode chips;
A method for producing a light-emitting diode chip, comprising:   2. The light-emitting diode chip manufacturing method according to claim 1, wherein a cross-sectional shape of the first and second depressions formed in the first and second transparent substrate processing steps is any of a triangular shape, a square shape, and a circular shape. Method. In the wafer back surface processing step, the recess or the groove is formed by any one of a cutting blade, etching, sand blast, and laser,
2. The method of manufacturing a light-emitting diode chip according to claim 1, wherein in the first and second transparent substrate processing steps, the first and second depressions are formed by any one of etching, sandblasting, and laser.   The transparent substrate is formed of any one of transparent ceramics, optical glass, sapphire, and transparent resin, and the transparent substrate is attached to the wafer using a transparent adhesive in the integration step. Manufacturing method of light emitting diode chip.