JP4857838B2 - Method for manufacturing light emitting device - Google Patents

Description

  The present invention relates to a method of manufacturing a light emitting element having a tapered surface by processing a main surface of a nitride semiconductor substrate.

  In general, a dicer or a scriber is used to cut out a chip which is a light emitting element from a substrate on which semiconductor layers are stacked. A dicer is also called a dicing saw, and is a device that performs half-cut or full-cut of a substrate by rotating a blade embedded with diamond at a high speed.

  On the other hand, the scriber includes a diamond scriber and a laser scriber. A diamond scriber is a device that forms a thin scribe groove on a substrate by reciprocating linear motion of a needle embedded with diamond at the tip. A laser scriber irradiates a laser beam on the substrate to form a thin scribe groove on the substrate. Device.

  The substrate on which the scribe grooves are formed by such a method can be divided into chips by applying an external force with, for example, a braking device or a roller.

  In the case of a very hard substrate such as a sapphire substrate, a method of dividing the substrate into chips by the above-described method after polishing the substrate thinly to about 100 μm is generally performed.

  Recently, in manufacturing a light emitting device such as a blue light emitting diode, a nitride semiconductor substrate such as GaN has been used to improve chip characteristics.

  Further, attempts have been made to improve the light extraction by forming a tapered surface on the chip.

  For example, Patent Document 1 discloses a method of forming a tapered surface on a semiconductor crystal substrate made of a GaN bulk crystal.

This is because the electrode forming surface side of a GaN bulk crystal substrate polished to a thickness of 150 μm is attached to an adhesive tape and diced using a dicer to form a V-shaped tapered groove in a lattice pattern on the back surface of the substrate. It is to form. This shows that the light extraction of the light emitting element is improved.
International Publication No. 2005/011007 Pamphlet

  However, according to this method, since the GaN bulk crystal is very hard, wear of the dicing blade is remarkable, and a tapered groove having a stable shape cannot be formed.

  Further, when the tapered groove is formed, cracks and chips at positions different from the original divided position of the light emitting element frequently occur due to vibration of the dicing blade applied to the substrate, clogging of the tapered groove, and the like.

  Therefore, a tapered surface that is sufficiently effective for extracting light from the light emitting element cannot be formed with a high yield.

  Accordingly, an object of the present invention is to solve the problems with respect to the prior art and to provide a method for manufacturing a tapered nitride semiconductor light emitting device using a nitride semiconductor substrate with a high yield.

  In order to solve the above-described conventional problems, in the method for manufacturing a light emitting device of the present invention, first, laser irradiation is performed on the main surface side of the nitride semiconductor substrate, and scribe grooves are formed in a lattice shape in accordance with the size and shape of the device. To do. Then, the scribe groove is diced with a tapered dicing blade to form a tapered groove, and stress is applied to the tapered groove with a braking device or the like to separate the chips.

  In this method, it is possible to suppress a load applied in the depth direction of the substrate, which is a main cause of cracking or chipping of the substrate when forming the tapered groove. As a result, cracking and chipping of the substrate can be greatly reduced, and a tapered nitride semiconductor light emitting device using a nitride semiconductor substrate can be manufactured with a high yield.

  According to the method for manufacturing a light-emitting element of the present invention, it is possible to significantly suppress cracking and chipping when forming a tapered groove, and to manufacture a tapered nitride semiconductor light-emitting element using a nitride semiconductor substrate with a high yield. Can do.

1st invention of this application manufactures the light emitting element in which the main surface of the nitride semiconductor substrate by which the nitride semiconductor multilayer film containing the light emitting layer was laminated | stacked on the nitride semiconductor bulk crystal substrate was formed, and the taper surface was formed. A) irradiating the main surface with a laser beam to form a linear scribe groove in a desired chip shape; and b) using a tapered dicing blade on the scribe groove. A method for manufacturing a light-emitting element, comprising: a step of forming a linear tapered groove by dicing; and c) a step of applying stress to the nitride semiconductor substrate to separate the chip into chips.

  According to the present invention, there is an effect that a tapered nitride semiconductor light emitting device using the substrate can be manufactured with a high yield while suppressing cracking or chipping of the substrate when forming the tapered groove.

The second invention, the scribe groove, is a manufacturing method of the light emission element you and forming a groove group is a collection of scribed grooves having a plurality of parallel lines. According to the present invention, it is possible to further suppress cracking and chipping of the substrate when forming a tapered groove, and to manufacture a tapered nitride semiconductor light emitting device using the substrate with a higher yield. .

A third invention is the group of grooves is a method of manufacturing a light emission device you characterized in that the groove depth from their central groove increases toward the groove edge becomes shallower. According to the present invention, it is possible to further suppress cracking and chipping of the substrate when forming a tapered groove, and to manufacture a tapered nitride semiconductor light emitting device using the substrate with a higher yield. .

The fourth invention is on the primary surface is a manufacturing method of the light emission element you wherein a protective film is formed.

  According to the present invention, in step b), when contaminants adhere to the substrate surface, the substrate surface is contaminated by applying a protective film on the main surface in advance and removing it after forming the scribe groove. It has the effect | action that an object adhesion can be prevented.

A fifth invention is, count of the dicing blade is # 500 or more, a manufacturing method of the light emission element you wherein a # is 4500 or less. According to this invention, it has the effect | action that the taper surface of the said board | substrate and the crack and a chip | tip of the vicinity can be suppressed.

A sixth invention is the taper angle of the dicing blade is 30 ° or more, is a manufacturing method of the light emission element you wherein a is 120 ° or less. According to this invention, it has the effect | action that the taper surface of the said board | substrate and the crack and a chip | tip of the vicinity can be suppressed.

A seventh aspect of the invention, said step b) the rotation speed of the dicing blade 10000rpm or more at a manufacturing method of the light emission element shall be the equal to or less than 30000 rpm. According to this invention, it has the effect | action that the taper surface of the said board | substrate and the crack and a chip | tip of the vicinity can be suppressed.

An eighth invention is the scanning speed of the dicing blade in the step b) is 0.5 mm / sec or more, a manufacturing method of the light emission element you wherein a is 5 mm / sec. According to this invention, it has the effect | action that the taper surface of the said board | substrate and the crack and a chip | tip of the vicinity can be suppressed.

A ninth aspect of the invention, the nitride semiconductor bulk crystal substrate is a method for producing a GaN der Ru - emitting element. According to the present invention, it is possible to manufacture a tapered nitride semiconductor light emitting device using a GaN bulk crystal substrate with a high yield while suppressing cracking and chipping of the substrate.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  2A is a top view of the nitride semiconductor substrate, and FIG. 2B is a cross-sectional view taken along the line A-A ′ of FIG.

  In this figure, a light emitting element made of a nitride semiconductor multilayer film 20 is fabricated on a GaN substrate 10 having a thickness of 300 μm and 50 mmφ, and an n-electrode 30 and a p-electrode 40 are formed on the nitride semiconductor multilayer film 20 side. 50.

  First, the electrode surface of the substrate 50 was affixed to a ceramic affixing plate with wax, and mirror polished to a thickness of 150 μm using a grinding machine and a lapping device.

  And the board | substrate which finished grinding | polishing was peeled from the ceramic sticking board, and organic cleaning was performed.

  Next, preparation for forming a scribe groove in the substrate was performed.

  FIG. 3 is a diagram showing the arrangement of substrates for forming scribe grooves.

  Here, the electrode surface side of the substrate 60 after polishing was attached to the glass substrate 80 with the wax 70, and the glass substrate 80 was attached to the ultraviolet release sheet 100 adhered to the frame 90.

  In addition, although the board | substrate 60 is affixed on the glass substrate 80 here, when the thickness of the board | substrate 60 is thick, you may affix the board | substrate 60 directly to the ultraviolet rays peeling sheet 100. FIG.

  Then, after the substrate 80 was attached, the protective film 110 was formed on the substrate 60 using a spinner at 500 rpm. At this time, a material that can be easily washed with water is used for the protective film.

  After that, the laser beam 115 condensed by the lens 114 may be irradiated from above the protective film 110.

  4A is an enlarged view of the substrate on which the scribe groove is formed, and FIG. 4B is a cross-sectional view taken along line B-B ′ of FIG.

  In this way, the lattice-shaped scribe grooves 120 were formed from the polishing surface side of the substrate 60 using the laser scribe at the position corresponding to the central portion of the street between the respective electrode patterns constituting the light emitting element.

  At this time, a solid laser having a wavelength of 355 nm was used as the laser, and the scribing conditions were a laser power of 2 W, a laser defocus of −100 μm, and a laser scanning speed of 10 mm / second.

  Further, the laser irradiation position can be easily determined because the substrate 60 has transparency and the position of the street can be confirmed as shown by the broken line in FIG.

  Note that, when the groove width of the scribe groove 120 is increased as much as possible while maintaining the groove depth, the load applied to the substrate when the tapered groove is formed later is reduced.

  Therefore, the laser defocus is increased in the negative direction to widen the groove width, and then the laser power is increased or the laser scanning speed is decreased to ensure the groove depth.

  Thus, scribe grooves having a groove width of 25 μm and a depth of 70 μm could be formed in a 350 μm square lattice.

  FIG. 5 is a diagram showing the arrangement of the substrates for forming the tapered grooves.

  In this way, the substrate 130 on which the scribe groove has been formed is set on a dicer, and the scribe groove 120 is scanned on the scribe groove 120 at a scanning speed of 20000 rpm and 1 mm / second using a dicing blade 135 having a taper angle of 90 ° and a # 1000 count. Dicing was performed by tracing to form a tapered groove having a groove width of 140 μm and a groove depth of 70 μm.

  FIG. 6A is an enlarged view of a substrate in which a tapered groove is formed, and FIG. 6B is a cross-sectional view taken along line C-C ′ of FIG.

  At this point, the substrate 150 on which the tapered groove 140 was formed had almost no cracks or chips except for the wafer periphery of 1 mm.

  Here, as for the dicing conditions for forming the tapered groove, the blade count is preferably # 500 to # 4500. If it is smaller than # 500, large chipping is likely to occur, and conversely if it is larger than # 4500, the taper groove is clogged and difficult to cut.

  Next, the taper angle of the dicing blade is desirably 30 ° or more and 120 ° or less. If it is smaller than 30 °, cracks from the bottom portion of the tapered groove are likely to occur, and if it is larger than 120 °, cracks and chips from the edge portion of the tapered surface are likely to occur.

  Next, the rotational speed of the dicing blade is preferably 10,000 rpm or more and 30000 rpm or less. If it is slower than 10000 rpm, chipping is likely to occur due to clogging of the tapered groove, and if it is faster than 30000 rpm, the load may be excessively applied and the dicing blade may be damaged.

  The scanning speed of the dicing blade is desirably 0.5 mm / second or more and 5 mm / second or less. If it is slower than 0.5 mm / sec, the processing time will be significantly longer, and if it is faster than 5 mm / sec, the substrate will be frequently cracked or chipped.

  After forming the taper groove 140 in this manner, the glass plate was removed from the ultraviolet release sheet 100 attached to the frame 90, and the substrate was peeled off from the glass substrate 80 using an organic solvent and washed.

  After that, when the protective film 110 was removed by washing with water, the surface of the substrate was a clean surface free of contaminants.

  The protective film 110 may be removed immediately after the scribe groove is formed. However, if the taper groove is removed as in the present case, the grinding dust adhered to the substrate surface during the formation of the taper groove is reduced. It is more desirable because it can be removed at the same time.

  FIG. 7 is a diagram showing the arrangement of the substrates for breaking the substrates and separating them into chips.

  The substrate 150 having the taper groove formed in this manner was attached to the expanded sheet 160 bonded to the frame 90 so that the surface on the taper groove side becomes an adhesive surface.

  Here, when the depth of the scribe groove 120 formed by laser first is deeper than the depth of the taper groove 140 in the range of 10 μm to 30 μm, the chip cross-sectional shape is more beautiful when cutting by applying stress to the chip. Can be finished.

  Thereafter, the breaking blade 170 of the braking device was divided into chips by pressing and breaking in accordance with a position matching the bottom portion of the tapered groove of the substrate 150.

  On the other hand, a scribing groove may be separately formed with a laser at a position matching the bottom portion of the tapered groove on the electrode forming surface side of the substrate, and a breaking blade may be pressed from the tapered surface side to be divided into chips.

  Finally, by expanding the expanded sheet 160, individual tapered light-emitting elements could be manufactured with a high yield.

  FIG. 1A is a top view photograph of a tapered nitride semiconductor light emitting device manufactured by the above method, and FIG. 1B is a cross-sectional photograph thereof.

  The light-emitting elements manufactured in this manner had an appearance yield of 85% to 90%.

  On the other hand, the appearance yield of the light-emitting elements produced in the same manner only by dicing with a tapered blade as a conventional method was 50 to 70%.

  In addition, as for the dicing blade, the life of the dicing blade was extended to about three times that of the conventional method although the tip portion was slightly consumed even in this method.

(Embodiment 2)
Next, the manufacturing method of the light emitting element concerning Embodiment 2 of this invention is demonstrated.

  First, a nitride semiconductor substrate similar to that of the first embodiment was prepared, and the same process as that of the first embodiment was performed until the polishing step and the protective film formation.

  FIG. 8A is an enlarged view of a substrate on which a scribe groove is formed, and FIG. 8B is a cross-sectional view taken along line D-D ′ of FIG.

  As shown in this figure, at a position corresponding to the central portion of the street between the respective electrode patterns constituting the light emitting element, a lattice-like structure having a groove width of 25 μm and a depth of 70 μm using a laser scribe from the substrate polishing surface side. A scribe groove 180 was formed.

  Next, the scribe groove 190 and the scribe groove 200 were similarly formed in a lattice shape with a groove width of 20 μm and a depth of 30 μm at a position where the scribe groove 180 was translated by 30 μm on both sides thereof. As a result, a groove group 210 in which three scribe grooves were gathered was formed.

  The scribing conditions at this time are as follows: laser power is 2 W in the scribe groove 180, laser defocus is −100 μm, laser scanning speed is 10 mm / second, laser power is 0.5 W in the scribe grooves 190 and 200, laser The defocus was set to −100 μm, and the laser scanning speed was set to 10 mm / second.

  Here, as described above, the scribe groove 180 at the center of the groove group 210 serving as the chip dividing position has the deepest groove depth, and the scribe groove 190 and the scribe groove 200 on both sides thereof are shallower than the scribe groove 180. It becomes the groove depth.

  This is because the groove depth is determined in consideration of the portion to be cut into a taper shape by the dicing blade 135. By making the groove depth of the groove group 210 too deep, the groove group 210 of the groove group 210 is formed after the taper groove is formed. It is possible to prevent a part from remaining.

  Further, by further increasing the number of scribes in the groove group 210, the load applied to the dicing blade and the substrate is further reduced, the life of the dicing blade is further extended, and the cracks and chips of the substrate are further reduced.

  After that, by the same method as in the first embodiment, the cutting edge of the dicing blade 135 is aligned so as to match the position of the scribe groove 180 from the polishing surface side of the substrate 220, and diced so as to trace on the scribe groove 180, As shown in FIG. 6, a tapered groove 140 having a scribe groove width of 140 μm and a groove depth of 70 μm was formed in the same manner as in the first embodiment.

  At this time, almost no cracks or chips were found in the scribe grooves of the substrate 150 in which the tapered grooves 140 were formed.

  The final chip thus obtained had an appearance yield of 95% to 100%.

  In addition, the life of the dicing blade was extended to about five times that of the conventional method.

  Thus, by forming tapered grooves with a tapered dicing blade on a plurality of scribe grooves formed by laser scribe on the substrate, a tapered nitride semiconductor light emitting device can be formed with a higher appearance yield. did it.

  In this example, the substrate thickness is 150 μm, but the substrate thickness may be further increased. For example, when the substrate thickness is increased to 300 μm, the chip size is further increased, the tapered groove is deepened, or the laser groove is formed deeply in accordance with the chip dividing position from the back side of the surface where the tapered groove is formed. Can be easily divided into chips.

  In addition, when the nitride semiconductor bulk crystal substrate has the same thickness as when it is divided into chips from the beginning and is polished on both sides, the above-described substrate polishing step is not necessary.

  It is useful as a manufacturing method that can form a taper groove with greatly reduced cracks and chips by forming a scribe groove on a substrate and dicing the scribe groove with a tapered dicing blade.

It is a photograph of the nitride semiconductor light emitting element with a taper concerning Embodiment 1 of the present invention, (A) is a top surface micrograph, and (B) is the section photomicrograph. It is a figure which shows the nitride semiconductor substrate which concerns on Embodiment 1 of this invention, (A) is a top view, (B) is sectional drawing in the A-A 'line of FIG. 2 (A). The figure which showed arrangement | positioning of the board | substrate for forming the scribe groove | channel concerning Embodiment 1 of this invention. It is a figure which shows the board | substrate which formed the scribe groove | channel which concerns on Embodiment 1 of this invention, (A) is an enlarged view, (B) is sectional drawing in the B-B 'line of FIG. 4 (A). The figure which showed arrangement | positioning of the board | substrate for forming the taper groove | channel which concerns on Embodiment 1 of this invention. It is a figure which shows the board | substrate which formed the taper groove | channel which concerns on Embodiment 1 of this invention, (A) is an enlarged view, (B) is sectional drawing in the C-C 'line of FIG. 6 (A). The figure which showed arrangement | positioning of the board | substrate for breaking the board | substrate which concerns on Embodiment 1 of this invention, and isolate | separating it into a chip | tip. It is a figure which shows the board | substrate which formed the scribe groove | channel concerning Embodiment 2 of this invention, (A) is an enlarged view, (B) is sectional drawing in the D-D 'line | wire of FIG. 8 (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 GaN substrate 20 Nitride semiconductor multilayer film 30 N electrode 40 P electrode 50, 60 Substrate 70 Wax 80 Glass substrate 90 Frame 100 UV peeling sheet 110 Protective film 115 Laser beam 120 Scribe groove 130 Substrate 135 Dicing blade 140 Tapered groove 150 Substrate 160 Expand sheet 170 Breaking blade 180, 190, 200 Scribe groove 210 Groove group 220 Substrate

Claims (8)

A method of manufacturing a light emitting device having a tapered surface by processing a main surface of a nitride semiconductor substrate in which a nitride semiconductor multilayer film including a light emitting layer is laminated on a nitride semiconductor bulk crystal substrate, comprising: a ) Irradiating the main surface with a laser beam to form a linear scribe groove in a desired chip shape as a group of scribe grooves made up of a plurality of parallel lines ; b) a tapered dicing blade A step of dicing the scribe groove to form a linear tapered groove, and c) applying a stress to the nitride semiconductor substrate to separate the chip into chips. Manufacturing method. 2. The method of manufacturing a light emitting element according to claim 1, wherein the groove group has a groove depth that becomes shallower from a central groove toward an end groove . The method for manufacturing a light-emitting element according to claim 1, wherein a protective film is formed on the main surface . The method of manufacturing a light emitting element according to claim 1, wherein the dicing blade has a count of # 500 or more and # 4500 or less . 5. The method of manufacturing a light emitting device according to claim 1, wherein a taper angle of the dicing blade is 30 ° or more and 120 ° or less. 6. The method of manufacturing a light emitting device according to claim 1, wherein a rotation speed of the dicing blade in the step b) is 10000 rpm or more and 30000 rpm or less. The method of manufacturing a light emitting device according to claim 1, wherein a scanning speed of the dicing blade in the step b) is 0.5 mm / second or more and 5 mm / second or less. The method for manufacturing a light emitting device according to claim 1, wherein the nitride semiconductor bulk crystal substrate is GaN .