JP2017224724A - Method for manufacturing light-emitting diode chip and 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, and the light-emitting diode chip.SOLUTION: A method for manufacturing a light-emitting diode chip comprises: a wafer preparing step 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 is formed in each of the regions partitioned by a plurality of division schedule lines mutually crossing a surface of the laminate layer; a wafer rear surface processing step of forming a plurality of recesses or first grooves corresponding to each LED circuit on a rear surface of the wafer; a transparent substrate processing step of forming a plurality of second grooves corresponding to each LED circuit of the wafer on a surface of the transparent substrate; an integrating step of forming an integrated wafer by sticking the surface of the transparent substrate to the rear surface of the wafer; and a dividing step of dividing the integrated wafer into individual light-emitting diode chips by cutting the wafer together with the transparent substrate along the division schedule lines.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a light emitting diode chip manufacturing method and 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 these points, and an object of the present invention is to provide a method of manufacturing a light-emitting diode chip and a light-emitting diode chip that can obtain sufficient luminance.

  According to invention of Claim 1, it is a manufacturing method of a light emitting diode chip | tip, Comprising: It has a laminated body layer in which the several semiconductor layer containing a light emitting layer was formed on the transparent substrate for crystal growth, This laminated body layer A wafer preparation step of preparing a wafer in which LED circuits are formed in each region partitioned by a plurality of division lines intersecting each other on the surface of the wafer, and a plurality of recesses or corresponding to each LED circuit on the back surface of the wafer A wafer back surface processing step for forming a first groove, a transparent substrate processing step for forming a plurality of second grooves on the surface of the transparent substrate corresponding to each LED circuit of the wafer, the wafer back surface processing step, After performing the transparent substrate processing step, an integrated step of forming the integrated wafer by sticking the surface of the transparent substrate to the back surface of the wafer, and the transparent substrate along the line to be divided LED chip production method of which is characterized in that and a dividing step of dividing the integrated wafer into individual light emitting diode chips is provided by cutting with.

  Preferably, the cross-sectional shape of the second groove formed in the transparent substrate processing step is any one of a triangular shape, a quadrangular shape, and a semicircular shape. Preferably, the recess or the first groove formed in the wafer back surface processing step is formed by any one of a cutting blade, etching, sand blast, and laser, and the second groove formed in the transparent substrate processing step is a cutting blade. , Etching, sandblasting, or 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.

  According to invention of Claim 5, it is a light emitting diode chip | tip, Comprising: The light emitting diode in which the LED circuit was formed in the surface, and the recessed part or the 1st groove | channel was formed in the back surface, and the transparent stuck on the back surface of this light emitting diode And a light emitting diode chip in which a second groove is formed on a surface of the transparent member to which the light emitting diode is attached.

  In the light-emitting diode chip of the present invention, the second groove is formed on the surface of the transparent member adhered to the back surface of the LED, so that the surface area of the transparent member is increased and the LED light-emitting layer is irradiated. Since light incident on the transparent member is refracted in a complicated manner in the concave portion or the first groove and the second groove portion, the incident angle at the interface between the transparent member and the air layer is reduced when light is emitted from the transparent member. The ratio of light above the critical angle is decreased, the amount of light emitted from the transparent member is increased, and the luminance 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 transparent substrate processing step, and FIGS. 6B to 6D are cross-sectional views showing the formed groove shape. FIG. 7A is a perspective view showing an integration process in which a transparent substrate having a plurality of grooves extending in the first direction on the front surface is attached to the back surface of the wafer and integrated, and FIG. It is a perspective view of a wafer. It is a perspective view which shows the integration process which sticks the back surface of a wafer and integrates the transparent substrate which has the some groove | channel extended in the 2nd direction orthogonal to a 1st direction and a 1st direction on the surface. 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. 12 (A) to 12 (C) are perspective views of the light emitting diode chip according to the 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 electroformed 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 wafer back surface processing step, the transparent substrate processing step of forming a plurality of grooves corresponding to the LED circuit 19 on the front surface 21a of the transparent substrate 21 to be attached to the back surface 11b of the wafer 11 is performed. To do.

  This transparent substrate processing step is performed using, for example, a well-known cutting device. In the transparent substrate processing step of forming the plurality of grooves 23 on the surface 21a of the transparent substrate 21, the transparent substrate 21 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 surface 21a of the transparent substrate 21 while rotating at a high speed in the arrow R direction, and the transparent substrate 21 held on the chuck table (not shown) is processed and fed in the arrow X1 direction. Grooves 23 extending in the direction of are formed by cutting.

  The surface 21a of the transparent substrate 21 is cut while indexing and feeding the transparent substrate 21 in the direction orthogonal to the direction of the arrow X1 by the pitch of the division lines 17 of the wafer 11, and in the first direction as shown in FIG. A plurality of extending grooves 23 are formed one after another.

  As shown in FIG. 7A, the plurality of grooves 23 formed on the surface 21a of the transparent substrate 21 may be extended only in one direction. Alternatively, as shown in FIG. A plurality of grooves 23 extending in the direction and the second direction orthogonal to the first direction may be formed on the surface 21 a of the transparent substrate 21.

  The groove formed on the surface 21a of the transparent substrate 21 is a groove 23 having a triangular cross section as shown in FIG. 6B, or a groove 23A having a square cross section as shown in FIG. 6C, or FIG. Any of the grooves 23B having a semicircular cross section 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 method for forming the groove, sand blasting, etching, or laser may be used.

  Integration of forming the integrated wafer 25 by performing the transparent substrate processing step of forming the plurality of grooves 23, 23 </ b> A, 23 </ b> B on the front surface 21 a of the transparent substrate 21 and then sticking the transparent substrate 21 to the back surface 11 b of the wafer 11. Perform the process.

  In this integration step, as shown in FIG. 7A, the back surface 11b of the wafer 11 is attached to the surface of the transparent substrate 21 having a plurality of grooves 23 extending in the first direction on the surface 21a. As shown in FIG. 7B, the wafer 11 and the transparent substrate 21 are integrated to form an integrated wafer 25.

  As an alternative embodiment, a surface 21a of a transparent substrate 21 having a plurality of grooves 23 extending in a first direction and a second direction orthogonal to the first direction is shown in FIG. As described above, the wafer 11 and the transparent substrate 21 may be integrated by bonding the back surface 11b of the wafer 11 with a transparent adhesive. Here, the pitch of the grooves 23 formed on the surface 21 a of the transparent substrate 21 corresponds to the pitch of the division lines 17 of the wafer 11.

  After performing the integration step, as shown in FIG. 9, 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 to form a frame unit. A supporting step of supporting the wafer 25 with the annular frame F via the dicing tape T is performed.

  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 cutting 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. By setting the 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. 12A has a transparent member 21A attached to the back surface of the LED 13A having the LED circuit 19 on the front surface. Further, the recess 5 or the groove 3 is formed on the back surface 11b of the wafer 11, and the groove 23 is formed on the surface of the transparent member 21A.

  Therefore, in the light-emitting diode chip 31 shown in FIG. 12A, the groove 23 is formed on the surface of the transparent member 21A, so the surface area of the transparent member 21A increases. 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 formed on the concave portion 5 or the groove 3 formed on the back surface 11b of the wafer 11 and further on the surface of the transparent member 21A. The light enters the transparent member 21A after being refracted by the groove 23 portion.

  Therefore, when the light is refracted and emitted from the transparent member 21A to the outside, 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.

  In the light emitting diode chip 31A shown in FIG. 12B, in addition to the recess 5 or the groove 3 being formed on the back surface of the LED 13A, the transparent member 21A having a groove 23A having a square cross section on the front surface on the back surface of the LED 13A. It is bonded with a transparent adhesive.

  Also in the light emitting diode chip 31A of the present embodiment, a part of the light emitted from the LED circuit 19 and incident on the transparent member 21A is formed on the back surface of the LED 13A, similarly to the light emitting diode chip 31 shown in FIG. The light enters the transparent member 21A after being refracted by the recessed portion 5 or groove 3 and the groove 23A formed on the surface of the transparent member 21A.

  Therefore, when the light is emitted from the transparent member 21A to the outside, the ratio of light whose incident angle at the interface between the transparent member 21A and the air layer is equal to or greater than the critical angle is reduced, and the amount of light emitted from the transparent member 21A is increased. As a result, the luminance of the light emitting diode chip 31A is improved.

  Referring to FIG. 12C, a perspective view of a light emitting diode chip 31B of still another embodiment is shown. In the light emitting diode chip 31B of the present embodiment, the recess 5 or the groove 3 is formed on the back surface of the LED 13A, and the grooves 23A having a square cross section are formed on the surface of the transparent member 21A in a direction perpendicular to each other.

  Accordingly, the light emitted from the LED circuit 19 and incident on the transparent member 21A is refracted and incident on the concave portion 5 or the groove 3 formed on the back surface of the LED 13A and the groove 23A portion formed on the surface of the transparent member 21A. The amount of light increases.

  Accordingly, since the amount of light whose incident angle at the interface between the transparent member 21A and the air layer is equal to or greater than the critical angle is decreased, the amount of light emitted from the transparent member 21A is increased, and the light emitting diode chip 31D Brightness is improved.

  In the embodiment shown in FIGS. 12A to 12C, the transparent member 21A has the groove 23A having a triangular cross section or the groove 23A having a square cross section, but the transparent member 21A is shown in FIG. The same effect is obtained when the groove 23B having a semicircular cross section shown in FIG.

2 Mask 3, 3A, 3B Groove 4 Hole 5, 5A, 5B Recess 7 Groove 9 Recess 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 23, 23A, 23B Groove 25 Integrated wafer 27 Cutting groove 31, 31A, 31B Light emitting diode chip

Claims (5)

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;
A wafer back surface processing step for forming a plurality of recesses or first grooves corresponding to each LED circuit on the back surface of the wafer;
A transparent substrate processing step of forming a plurality of second grooves corresponding to each LED circuit of the wafer on the surface of the transparent substrate;
An integration step of forming an integrated wafer by sticking the surface of the transparent substrate to the back surface of the wafer after performing the wafer back surface processing step and the transparent substrate processing step;
A dividing step of cutting the wafer along with the transparent substrate together with the transparent substrate to divide the integrated wafer into individual light emitting diode chips;
A method for producing a light-emitting diode chip, comprising:   The method of manufacturing a light-emitting diode chip according to claim 1, wherein a cross-sectional shape of the second groove formed in the transparent substrate processing step is any one of a triangular shape, a square shape, and a semicircular shape. In the wafer back surface processing step, the recess or the first 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 transparent substrate processing step, the second groove is formed by any one of a cutting blade, etching, sand blasting, 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. A light emitting diode chip,
A light emitting diode in which an LED circuit is formed on the front surface and a recess or a first groove is formed on the back surface;
A transparent member attached to the back surface of the light emitting diode,
A light emitting diode chip in which a second groove is formed on a surface of the transparent member attached to the light emitting diode.