JP2009059773A - Manufacturing method of semiconductor laser device - Google Patents

Abstract

A method of manufacturing a semiconductor laser device excellent in chip-shaped yield is provided.
A method of manufacturing a semiconductor laser device for manufacturing a plurality of chips having a light emitting region 2 on a substrate 1 is provided on a second main surface facing the first main surface on the side where the light emitting region is formed. In addition, a step of forming the first groove 4 in a broken line shape in a direction parallel to the laser emission direction 5 and cleaving in a direction perpendicular to the laser emission direction 5 make the cleavage plane a plurality of resonator planes. Forming the laser array, forming the second groove 10 on the second main surface so as to be continuous with the first groove 4 formed in a broken line, and the first main surface side And cleaving the laser array along the second groove 10 to form a plurality of chips.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a semiconductor laser device, and more particularly to a method for separating a laser chip from a laser wafer.

  In the manufacture of semiconductor laser devices, the formation of an epitaxial layer serving as a light emitting region on a semiconductor substrate, the formation of electrode patterns on the front and back surfaces, the formation of an array by primary cleavage, and the protection to the resonator surface (primary cleavage surface) After the films are formed in order, the chips are separated by secondary cleavage.

  Hereinafter, a conventional method for manufacturing a semiconductor laser device will be described with reference to FIGS.

  First, as shown in FIG. 4A, an epitaxial layer 102 serving as a light emitting region is formed on the surface side of a substrate 101 made of GaN having a thickness of 100 μm, for example, and a surface electrode pattern is formed on the surface of the epitaxial layer 102. 106 (see FIG. 4B described later) is formed, and a back electrode pattern 103 is formed on the back surface of the substrate 101 facing the front surface. In the semiconductor wafer having such a structure, for example, an element isolation groove 104 having a depth of 2 μm is formed between the back surface electrode patterns 103 of the substrate 101 so as to be parallel to the laser beam emission direction 105.

  Next, as shown in FIG. 4B, in order to form a laser resonator, the semiconductor wafer is first cleaved along a pre-formed scribe groove in a direction perpendicular to the laser beam emitting direction 105. Then, a laser array having the resonator surface 107 formed by cleavage is formed (for example, a resonator length of 600 μm).

  Next, as shown in FIG. 4C, after forming a protective film (not shown) on the resonator surface 107 of the laser array, the blade 108 is pressed from the surface side of the laser array to a position corresponding to the element isolation groove 104. Then, separate into laser chips. In this case, ideally, separation occurs from the element isolation trench 104, and a laser chip is normally formed as shown in FIG.

However, in reality, as shown in FIG. 4E, separation caused by an abnormality such as a chip breaking from a portion other than the formed element isolation groove 104 occurs. This is because a deep groove is formed when the element isolation groove 104 is formed in consideration of the possibility that the array may be broken during the process of forming the protective film on the resonator surface 107 after arraying the semiconductor wafer. As a result, there is a problem that the chip breaks from a place other than the element isolation groove 104 as shown in FIG.
JP-A-5-75216

  In view of the above problems, a method of forming an element isolation groove 104 to be an element isolation groove after forming a protective film (not shown) on the resonator surface 107 is also conceivable. As shown in FIG. In addition, when a deep element isolation groove 104 (for example, a depth of 50 μm) that reaches the resonator surface 107 is formed, the protective film formed on the resonator surface 107 peels off 5A as shown in FIG. On the other hand, as shown in FIG. 6A, a deep element isolation groove 104 (for example, a depth of 50 μm and a length of 560 μm with respect to a resonator length of 600 μm) is formed as shown in FIG. 6A. In this case, as shown in FIG. 6 (b), there arises a problem that a chip end chip 6A occurs. In particular, in a blue-violet laser using a gallium nitride-based material having a hexagonal crystal structure, it easily breaks in the direction of 30 ° with respect to the resonator surface 107 which is a cleavage plane, and the chip end chipping 6A exceeds 50 μm. There are many.

  In view of the above, an object of the present invention is to provide a method of manufacturing a semiconductor laser device excellent in chip-shaped yield.

  In order to achieve the above object, a method of manufacturing a semiconductor laser device according to an aspect of the present invention includes a semiconductor laser device that manufactures a plurality of chips each having a light emitting region formed of a plurality of epitaxial layers on a substrate. In the manufacturing method, the first groove is formed in a direction parallel to the laser emission direction from the light emitting region on the second main surface facing the first main surface on the side where the light emitting region is formed in the substrate. Forming a plurality of laser arrays having the cleavage plane as a resonator plane by cleaving the substrate including the light emitting region in a direction perpendicular to the laser emission direction, A step of forming a second groove on the main surface of 2 so as to be continuous with the first groove formed in a broken line, and a laser array from the first main surface side along the second groove Form multiple chips by cleaving And a step.

  In the method for manufacturing a semiconductor laser device according to one aspect of the present invention, the light emitting region is preferably made of a group III nitride semiconductor material.

  In the method for manufacturing a semiconductor laser device according to one aspect of the present invention, the step of forming the second groove is preferably formed by laser scribing.

  In the method for manufacturing a semiconductor laser device according to one aspect of the present invention, the distance between the bottom of the second groove and the light emitting region is preferably 30 μm or more.

  According to the manufacturing method of the semiconductor laser device according to one embodiment of the present invention, the yield of the chip shape can be improved. In particular, in a blue-violet laser composed of a group III nitride semiconductor having a hexagonal crystal structure, it is difficult to form a rectangular chip because there is no cleavage plane in the direction perpendicular to the cavity plane formed by cleavage. Therefore, a great effect is expected in the present invention. Further, when the scribe groove for element isolation is formed by laser scribe, it is easy to form a deep groove, so that the yield of the chip shape can be easily improved. However, if the scribe groove formed by laser scribe is deep and the bottom of the scribe groove is too close to the light emitting region, the light emitting layer is damaged. Therefore, the distance between the bottom of the element separating scribe groove and the light emitting layer is set to 30 μm or more. As a result, the yield of the chip shape can be improved while maintaining reliability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
Hereinafter, a method of manufacturing the semiconductor laser device according to the first embodiment of the present invention will be described with reference to FIGS.

  First, as shown in FIG. 1A, a plurality of epitaxial layers 2 serving as light emitting regions are formed on the surface side of a substrate 1 made of n-type GaAs having a thickness of 100 μm, for example. Here, the epitaxial layer 2 is composed of a III-V group compound semiconductor including a quantum well active layer made of GaInP and a clad layer made of AlGaInP grown by the MOVPE method. A surface electrode pattern 6 (see FIG. 1B described later) is formed on the surface of the epitaxial layer 2, and the back surface (second main surface) side facing the surface (first main surface) side of the substrate 1. A back electrode pattern 3 is formed on the substrate. In the semiconductor wafer having such a structure, the V-shaped element isolation groove 4 is formed in a broken line shape (intermittently) by, for example, etching so as to be parallel to the laser beam emitting direction 5 between the back electrode patterns 3 on the substrate 1. ) To form. Here, the element isolation grooves 4 have, for example, a width of 10 μm, a depth of 5 μm, a length of 40 μm, and a pitch of 600 μm. If the width of the element isolation groove 24 is too narrow, it is difficult to form a deep groove. On the other hand, if the width is too wide, the effect of the role of a guide for element isolation is reduced. Therefore, the width is preferably 10 to 20 μm. .

  Next, as shown in FIG. 1B, in order to form a laser resonator, a scribe groove (not shown) for primary cleavage is formed at an edge on the epitaxial layer side of the semiconductor wafer, and then the semiconductor wafer is A laser array having a resonator surface 7 formed by cleaving is formed by pressing a blade against a portion corresponding to a scribe groove from the side and performing primary cleavage in a direction perpendicular to the laser beam emission direction 5 (for example, a resonator (600 μm long). The surface electrode pattern 6 shown in the figure is formed at a pitch of 200 μm. Although not shown, after that, for example, a protective film having a reflectance of 10% is formed on one surface of the resonator surface 7, and a protective film having a reflectance of 90% is formed on the other surface.

  Next, as shown in FIG. 1C, a scribe groove 10 having a length of 560 μm is formed by, for example, diamond scribe so that the element isolation grooves 4 are continuous with each other in parallel with the laser beam emission direction 5. The depth of the scribe groove 10 is about 2 μm.

  Next, as shown in FIG. 1D, the blade 8 is pressed against a portion corresponding to the scribe groove 10 in the epitaxial layer to be separated into laser chips. Here, since the deep element isolation groove 4 is formed in the vicinity of the resonator surface 7, the laser chip can be manufactured stably. That is, the element isolation groove 4 is formed before forming the laser array, but is formed intermittently in a broken line shape, so that there is a risk of damage such as breakage of the array in the protective film forming process as in the prior art. Can be prevented. Further, although the scribe groove 10 is formed after the protective film forming step, the depth of the scribe groove 10 is shallower than the depth of the element isolation groove 4, so that even if chip chipping occurs, the chip is chipped. The influence on the surface can be eliminated and the automatic recognition during mounting can be prevented from being hindered.

(Second Embodiment)
A method for manufacturing a semiconductor laser device according to the second embodiment of the present invention will be described below with reference to FIGS.

  First, as shown in FIG. 2A, a plurality of epitaxial layers 22 serving as light emitting regions are formed on the surface side of a substrate 21 made of n-type GaN having a thickness of 100 μm, for example. Here, the epitaxial layer 22 is composed of a group III compound semiconductor including a quantum well active layer made of InGaN and a clad layer made of AlGaN grown by the MOVPE method. A surface electrode pattern 26 (see FIG. 2B described later) is formed on the surface of the epitaxial layer 22, and the back surface (second main surface) side facing the front surface (first main surface) side of the substrate 21. A back electrode pattern 23 is formed on the substrate. In the semiconductor wafer having such a structure, the element isolation grooves 24 are formed in a broken line shape (intermittently) by, for example, dry etching so as to be parallel to the laser beam emission direction 25 between the back surface electrode patterns 23 on the substrate 21. To do. Here, the element isolation grooves 24 have, for example, a width of 10 μm, a depth of 10 μm, a length of 60 μm, and a pitch of 600 μm.

  Here, if the width of the element isolation groove 24 is too narrow, it is difficult to form a deep groove. On the other hand, if the width is too large, the effect of the role of a guide for element isolation is reduced. It is preferable. In the case of the group III nitride semiconductor laser of this embodiment, since the crystal structure is a hexagonal crystal, it is difficult to shape the rectangle. Therefore, the depth of the element isolation groove 24 is desirably 10 μm or more.

  Next, as shown in FIG. 2B, in order to form a laser resonator, a scribe groove (not shown) for primary cleavage is formed at an edge on the epitaxial layer side of the semiconductor wafer, and then the semiconductor wafer is A laser array having a resonator surface 27 formed by cleaving is formed by pressing a blade against a portion corresponding to a scribe groove from the side and performing primary cleavage in a direction perpendicular to the laser light emitting direction 25 (for example, a resonator (600 μm long). The surface electrode pattern 26 shown in the figure is formed with a pitch of 200 μm. Although not shown, after that, for example, a protective film having a reflectance of 10% is formed on one surface of the resonator surface 27, and a protective film having a reflectance of 90% is formed on the other surface.

  Next, as illustrated in FIG. 2C, a scribe groove 30 having a length of 570 μm is formed by laser scribing so that the element isolation grooves 24 are continuous with each other in parallel with the laser beam emission direction 25. The depth of the scribe groove 30 is about 50 μm. Although the laser scribe is used here, a deep groove can be formed as the laser power used for forming the scribe groove 30 is increased.

  Next, as shown in FIG. 2 (d), the blade 28 is pressed against a portion corresponding to the scribe groove 30 in the epitaxial layer to separate the laser chip. Here, since the element isolation groove 24 as deep as 50 μm is formed in the vicinity of the resonator surface 27, even a blue-violet laser using a group III nitride semiconductor of a GaN-based material having a crystal structure is used. The laser chip can be manufactured stably. As in the first embodiment, the element isolation grooves 24 are formed before the laser array is formed. However, since the element isolation grooves 24 are intermittently formed in a broken line shape, the protective film forming step is performed as in the conventional case. It is possible to prevent the possibility of damage such as breakage of the array.

  FIG. 3A shows a relationship diagram between the number of arrays and yield (%) for explaining an example of chip-shaped yield in the present embodiment.

  As shown in FIG. 3A, the average yield is improved to 99% when the manufacturing method of the semiconductor laser device of this embodiment is used, whereas the conventional yield is 87% on the average. I was able to.

  FIG. 3B shows a relationship diagram between the distance from the bottom of the scribe groove 30 to the epitaxial layer 22 serving as the light emitting region and the operating current change rate.

  The device isolation can be expected to be more stable as the scribe groove 30 is deeper. However, if the bottom of the scribe groove 30 is too close to the light emitting region, the active layer may be damaged, which may affect the reliability of the laser chip. In the blue-violet laser of this embodiment, using a laser chip manufactured by changing the depth of the scribe groove 30 for element isolation, a 65 mW, CW APC energization test was performed at 70 ° C., and the operating current change after 150 h energization The rate ΔIop was evaluated.

  As shown in FIG. 3B, it was found that ΔIop at which the distance from the bottom of the scribe groove 30 to the light emitting region is 30 μm or less increases. Therefore, by making the distance from the bottom of the scribe groove 30 to the light emitting region larger than 30 μm, the yield of the shape of the laser chip can be improved while maintaining high reliability. The distance from the bottom of the scribe groove to the light emitting region can be similarly applied to the first embodiment.

  The semiconductor laser device manufacturing method of the present invention is useful for manufacturing a DVD light source, a Blu-ray disc light source, or the like.

(A)-(e) is a figure for demonstrating the manufacturing method of the semiconductor laser apparatus concerning the 1st Embodiment of this invention. (A)-(e) is a figure for demonstrating the manufacturing method of the semiconductor laser apparatus based on the 2nd Embodiment of this invention. (A) is a related figure of the yield of a chip shape and the number of arrays in the manufacturing method of the semiconductor laser device concerning a 2nd embodiment of the present invention, and (b) is a 2nd embodiment of the present invention. FIG. 5 is a relationship diagram between a distance between a scribe groove and a light emitting region and an operating current change rate in the method of manufacturing a semiconductor laser device. (A)-(e) is a figure for demonstrating the manufacturing method of the conventional semiconductor laser apparatus, and its subject. (A) And (b) is a figure for demonstrating the manufacturing method of the conventional semiconductor laser apparatus, and its subject. (A) And (b) is a figure for demonstrating the manufacturing method of the conventional semiconductor laser apparatus, and its subject.

Explanation of symbols

1, 2, 101 Substrate 2, 22, 102 Light emitting region 3, 23, 103 Back electrode pattern 4, 24, 104 Element isolation groove 5, 25, 105 Laser emission direction 6, 26, 106 Surface electrode pattern 7, 27, 107 Resonator face 8, 28, 108 Blade 10, 30 Scribe groove

Claims (4)

A method for manufacturing a semiconductor laser device for manufacturing a plurality of chips having a light emitting region constituted by a plurality of epitaxial layers on a substrate,
On the second main surface of the substrate facing the first main surface on the side where the light emitting region is formed, the first groove is broken in a direction parallel to the laser emission direction from the light emitting region. Forming, and
Cleaving the substrate including the light emitting region in a direction perpendicular to the laser emission direction to form a plurality of laser arrays having the cleavage plane as a resonator plane;
Forming a second groove on the second main surface of the substrate so as to be continuous with the first groove formed in a broken line;
Forming the plurality of chips by cleaving the laser array along the second groove from the first main surface side. In the manufacturing method of the semiconductor laser device according to claim 1,
The method for manufacturing a semiconductor laser device, wherein the light emitting region is made of a group III nitride semiconductor material. In the manufacturing method of the semiconductor laser device according to claim 2,
The step of forming the second groove is a method of manufacturing a semiconductor laser device, which is formed by laser scribing. In the manufacturing method of the semiconductor laser device according to claim 3,
A method of manufacturing a semiconductor laser device, wherein a distance between a bottom of the second groove and the light emitting region is 30 μm or more.

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