JP2008311547A - Semiconductor laser device and manufacturing method - Google Patents

Abstract

Kind Code: A1 The present invention drastically improves the cleaving accuracy for forming a resonant surface of a semiconductor laser device, and improves the yield of characteristics of the semiconductor laser device.
A semiconductor laser device according to the present invention includes an active layer including a light emitting portion on a substrate, a striped waveguide 204 formed in the active layer, an electrode for supplying current to the active layer, The first upper electrode 206 electrically connected to the electrode, and a pair of resonant surfaces in the waveguide 204 facing each other. The first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the resonance surface vicinity region 207 and is reduced as the width in the direction perpendicular to the waveguide 204 approaches the resonance surface. Each resonance surface is cleaved along a cleavage guide groove 203 formed in at least the active layer of the active layer and the substrate.
[Selection] Figure 8

Description

  The present invention relates to a semiconductor laser device and a manufacturing method thereof.

Recently, gallium nitride-based compound semiconductor and _{(In x Al y Ga 1-} X-Y N, X + Y ≦ 1,0 ≦ X, 0 ≦ Y) materials, semiconductor having an emission wavelength in a wavelength region of ultraviolet region from blue Research on laser diodes has been actively conducted. In general, a semiconductor laser device uses a semiconductor material having a band gap corresponding to an intended emission wavelength, and has a laminated structure such as an active layer serving as a light-emitting portion, a carrier transport to the active layer, and a cladding layer that functions to confine light. Make it. The laminated structure is such that a crystal is grown on a substrate such as a silicon (Si) substrate, a sapphire single crystal (Al ₂ O ₃ ) substrate, a gallium nitride (GaN) substrate, etc. After forming an electrode or the like for injecting silicon, each element is formed by cleaving the substrate.

  The cleavage of the substrate forms a resonant surface of the laser light waveguide as the element is divided. In order to form the resonance surface, the orientation is perpendicular to the waveguide and intended to expose the crystal plane of the substrate material. A common cleaving method uses a scriber to intentionally make dot-shaped scratches (point scribes) at equal intervals along the wafer's resonant surface, and then draw a very thin scribe line at the end of the resonant surface. The scribe line is used as an inlet and the point scribe is used as a guide to apply an external force from the back side of the wafer to the position of the resonance surface. For this reason, the work of applying point scribes to all the resonance surfaces is a very complicated work. Patent Document 1 discloses a technique for forming in advance a cleavage guide groove having a depth reaching the substrate at a position to be a resonance surface in a diffusion process. With this technique, it is possible to cleave the substrate without the complicated task of attaching point scribes.

Even when the substrate can be cleaved with high accuracy, the metal that becomes the electrode of the element formed on the cleavage surface is not divided along the cleavage surface of the substrate, and an electrode beam remains on the cleavage surface, or the cleavage surface. As a result, there is a problem in that electrode peeling occurs in the internal direction of the waveguide. In order to prevent an abnormal shape of the electrode that occurs due to cleavage, for example, in Patent Document 2, a stripe-shaped positive electrode formed on a waveguide is formed in a pattern that avoids only the vicinity of the resonance surface, and the positive electrode itself is A method of forming a semiconductor laser element without dividing is disclosed.
JP 2006-286703 A JP-A-10-27939

  According to the conventional method of cleaving a substrate in which the cleavage guide groove is provided on the resonance surface, it is possible to cleave the substrate without performing complicated work, but because the hardness of the sapphire substrate and the gallium nitride substrate is high, Cracking or chipping occurs with cleavage. In addition, when an external force is applied from the back side of the wafer, the cleavage plane is deviated from the target crystal plane, and another crystal plane is exposed in spite of the presence of the cleavage guide groove. There are still problems such as irregularities on the cleavage plane. For this reason, a technique for performing cleavage with high accuracy and good reproducibility has not been sufficiently established, and cleavage is one of the main factors that lower the yield of semiconductor laser devices.

  In addition, the method of forming the electrode with a pattern that avoids only the vicinity of the resonance surface is effective in preventing electrode flash and peeling due to cleavage, but has an effect on improving the cleavage accuracy of the substrate. Absent.

  The low cleavage accuracy causes a bad influence on the characteristic yield of the semiconductor laser device. In particular, the divergence angle of the laser beam is related to the accuracy of the cleavage plane. If the accuracy of cleavage is low, the number of elements that exhibit anomalies that cause far field patterns (FFP) to deviate from the symmetrical distribution form increases. I know.

  SUMMARY OF THE INVENTION In view of the above-described conventional problems, the present invention provides a semiconductor laser device that performs cleaving with high accuracy without reducing the manufacturing process, reduces FFP abnormality, and improves the characteristic yield. With the goal.

  To achieve the above object, the present invention reduces the semiconductor laser device as the first upper electrode is plane-symmetrical about the waveguide and the width in the direction perpendicular to the waveguide approaches the resonance surface. The configuration.

  Specifically, on a substrate, an active layer including a light emitting portion, a striped waveguide formed in the active layer, an electrode for supplying current to the active layer, an electrode formed on the electrode, Targeting a semiconductor laser device having an electrically connected upper electrode and a pair of mutually opposing resonant surfaces in a waveguide, the upper electrode is formed in plane symmetry around the waveguide in the vicinity of the resonant surface In addition, the width in the direction perpendicular to the waveguide is reduced as it approaches the resonance surface, and each resonance surface is cleaved guide formed at a boundary portion adjacent to the waveguide in the direction parallel to the waveguide. It is characterized by being cleaved along the groove.

  According to the semiconductor laser device of the present invention, the upper electrode is formed in plane symmetry with the waveguide as an axis, and the width in the direction perpendicular to the waveguide is reduced as it approaches the resonance surface. Since the cleavage guide groove is formed in the boundary adjacent to the direction parallel to the waveguide, the stress exerted on the GaN substrate by the first upper electrode can be concentrated at the position where the resonance surface and the waveguide intersect in the cleavage step. Therefore, a resonance surface with high crystallinity can be obtained with good reproducibility, and a decrease in characteristic yield such as an FFP abnormality can be improved.

  In the semiconductor laser device of the present invention, it is preferable that the width of the first upper electrode is the smallest and the same at the upper part of each cleavage plane.

  In this way, it is possible to use the resonant surfaces at both ends formed in the semiconductor laser element as the emitting surface and the reflecting surface.

  In the semiconductor laser device of the present invention, it is preferable that the upper electrode is formed in plane symmetry with a center line in a direction perpendicular to the waveguide as an axis.

  In this way, in the cleavage step, the stress exerted on the GaN substrate by the first upper electrode can be more concentrated on the position where the resonance surface and the waveguide intersect, so that a resonance surface with high crystallinity can be obtained with good reproducibility. Thus, it is possible to improve a decrease in characteristic yield such as FFP abnormality.

  In the semiconductor laser device of the present invention, it is preferable that the width of the upper electrode in the direction perpendicular to the waveguide is continuously reduced.

  In the semiconductor laser device of the present invention, it is preferable that the minimum width of the upper electrode in the direction perpendicular to the waveguide is larger than the width of the waveguide.

  In the semiconductor laser device of the present invention, the electrode preferably has a region that does not cover the waveguide at at least one end of each cleavage plane.

  In the semiconductor laser device of the present invention, it is preferable that the cleavage guide groove has the bottom of the cleavage guide groove reaching the substrate.

  In this way, the semiconductor substrate can be cleaved with high accuracy.

  In the semiconductor laser device of the present invention, the depth of the cleavage guide groove is preferably 2 μm or more and 20 μm or less.

  In the semiconductor laser device of the present invention, the width of the cleavage guide groove in the direction parallel to the waveguide is preferably 1 μm or more and 30 μm or less.

  In the semiconductor laser device of the present invention, it is preferable that the cleavage guide groove has a planar shape in which at least one end of the cleavage guide groove in a direction perpendicular to the waveguide is inclined with respect to the waveguide.

  In the semiconductor laser device of the present invention, the substrate is preferably gallium nitride.

  According to the method of manufacturing a semiconductor laser device of the present invention, the step (a) of forming an active layer including a light emitting portion on a substrate in a wafer state, and assisting in cleaving the substrate at least with respect to the active layer and cleaving. A step (b) of forming a cleavage guide groove in a region including the surface, a step (c) of forming a striped waveguide in the active layer, and an electrode for supplying current to the active layer on the waveguide Step (d), forming an upper electrode connected to the electrode on the electrode (e), and cleaving the substrate in the wafer state with the aid of a cleavage guide groove to form a resonant surface of the waveguide In the step (e), the upper electrode has a plane symmetry with respect to the waveguide in the region including the cleavage plane and a width in a direction perpendicular to the waveguide is the cleavage plane. Forming to shrink as it approaches And butterflies.

  According to the method for manufacturing a semiconductor laser device of the present invention, it is possible to prevent the flashing and peeling of the electrodes due to cleavage without complicated work, and to accurately reproduce the cleavage plane having high crystallinity.

  In the method for manufacturing a semiconductor laser device according to the present invention, in step (e), the upper electrode is formed in plane symmetry about the cleavage plane in the direction perpendicular to the waveguide in the region including the cleavage plane. Is preferred.

  In this way, in the cleavage step (f), the stress exerted on the GaN substrate by the first upper electrode can be further concentrated at the position where the resonance surface and the waveguide intersect, so that the resonance surface with high crystallinity can be reproduced. It can be obtained well, and a decrease in characteristic yield such as FFP abnormality can be improved.

  In the method for manufacturing a semiconductor laser device of the present invention, in the step (b), the planar shape of the cleavage guide groove is such that the end of the cleavage guide groove in the direction perpendicular to the waveguide has a pointed portion with respect to the waveguide. It is preferable to form as follows.

  According to the semiconductor laser device of the present invention, since a resonant surface with high crystallinity can be obtained with good reproducibility without complicating the manufacturing process, it is possible to improve a decrease in characteristic yield such as FFP abnormality.

(One embodiment)
An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a cross-sectional configuration of a semiconductor laser device according to an embodiment of the present invention.

As shown in FIG. 1, the semiconductor laser device of this embodiment includes an n-GaN layer 102 and an n-Al _a Ga _1-a N cladding layer (0 <a <1) 103 on a substrate 101 made of GaN. And an n-GaN optical guide layer 104, and a multi-quantum well activity comprising an In _X Ga _1-X N well layer and an In _Y Ga _1-Y N barrier layer (0 ≦ X <Y ≦ 1). layer 105, a p-GaN optical guide layer _{106, p-Al b Ga 1} -b N (0 <b <1) cladding layer 107 and p-GaN contact layer 108 are laminated, the thickness is 7～8Myuemu LD (Laser Diode) structure 109 is formed. The substrate 101 on which the LD structure 109 is formed may use silicon, sapphire, silicon carbide (SiC), or the like instead of GaN.

  A process for forming the cleavage guide, waveguide and electrode of the substrate 101 having the LD structure 109 thus formed will be described below.

  First, the process for forming the cleavage guide will be described. FIGS. 2A and 2B show a planar configuration of the substrate 101 having the LD structure 109. As an example, six semiconductor laser elements are shown.

  As shown in FIG. 2A, each semiconductor laser element in the substrate 101 is partitioned by a resonance plane line 201 and a secondary cleavage plane line 202 formed in a direction perpendicular to the resonance plane line 201.

  Next, as shown in FIG. 2B, a cleavage guide groove 203 is formed on the resonance surface line 201. The procedure for forming the cleavage guide groove 203 is as follows.

First, an insulating film made of SiO ₂ is deposited on the entire surface of the substrate 101, and a resist is applied. Thereafter, the resist at the position where the cleavage guide groove is to be formed is removed by photolithography and an opening is formed, and the insulating film in the portion where the resist is opened is etched. Next, the resist is removed, and chlorine-based dry etching is performed using an insulating film having an opening as a mask. In this way, it is possible to form the cleavage guide groove 203 having a depth of about 5 μm to 6 μm with respect to the LD structure 109 and the substrate 101. Finally, the insulating film on the entire surface of the wafer is removed by etching.

  Thus, the depth of the cleavage guide groove 203 formed by performing chlorine-based dry etching is preferably in the range of 2 μm or more and 20 μm or less. The reason why it is preferable that the depth of the cleavage guide groove is in the range of 2 μm to 20 μm will be described below.

First, it is desirable that the bottom of the cleavage guide groove 203 reaches the n-Al _a Ga _1-a N (0 <a <1) cladding layer 103 that affects the cleavage of the substrate 101. In one embodiment, the n-GaN layer 102 takes over the crystallinity of the substrate substantially intact, and the n-Al _a Ga _1-a N cladding layer 103 is aligned with the substrate and the n-GaN layer 102, so that n-Al _a Ga If the bottom of the cleavage guide groove 203 reaches the _1-a N (0 <a <1) cladding layer 103, the substrate 101 can be cleaved with high accuracy. Further, the n-GaN layer 102 and the n-Al _a Ga _1-a N cladding layer 103 in the LD structure 109 are thick layers, respectively, and have a total thickness of about 5.5 μm. Therefore, if the depth of the cleavage guide groove 203 is about 2 μm, the bottom of the cleavage guide groove has reached the vicinity of the bottom of the n-Al _a Ga _1-a N clad layer 103, and n− Cleavage extends to the GaN layer. For this reason, when the depth of the cleavage guide groove 203 is shallow so as to be less than 2 μm, the bottom of the cleavage guide groove 203 does not reach the n-Al _a Ga _1-a N (0 <a <1) cladding layer 103. The cleavage guide groove 203 cannot obtain the effect of guiding the cleavage. On the contrary, if the cleavage guide groove 203 is formed to have a groove deeper than 20 μm, the strength of the substrate cannot be maintained, and the cleavage surface is likely to be excessively formed by propagating through the cleavage guide groove 203. End up. For this reason, a crack occurs in the substrate in an unintended situation in the subsequent process, and a fatal damage frequently occurs.

  The width of the cleavage guide groove 203 in the direction parallel to the secondary cleavage plane line 202 is preferably 1 μm or more and 30 μm or less. If the thickness is less than 1 μm, the scribing blade is thick (about 10 μm), so that it is difficult to provide a scribe line serving as a cleaving inlet so as to be within the width of the cleavage guide groove 203. On the other hand, when a relatively thick groove of 30 μm or more is formed, the exposed cleaved surface fluctuates within the width of the cleaved guide groove 203, so that the resonance surface line 201 is formed uneven, and the ratio of affecting the resonance surface increases. .

  As for the planar shape of the cleavage guide groove 203, as shown in FIG. 3 (a), a rectangular shape having no special shape at both ends in the direction perpendicular to the secondary cleavage surface line 202 in the cleavage guide groove 203 ( b) a shape in which both end portions of the cleavage guide groove 203 in the direction perpendicular to the secondary cleavage surface line 202 protrude toward the outside of the cleavage guide groove 203, and a cleavage guide groove as shown in (c). A shape in which both end portions in a direction perpendicular to the secondary cleavage plane line 202 in 203 protrude toward the inside of the cleavage guide groove 203, as shown in (d), perpendicular to the secondary cleavage plane line 202 in the cleavage guide groove 203. Various shapes are conceivable, such as one end in one direction (b) and the other end (c). In the cleavage step, when an external force is applied from the back side of the wafer, the shape of the cleavage guide groove may be selected in accordance with the direction in which the external force is applied, and the shape is limited to the planar shape shown in FIGS. I can't. In the present embodiment, the cleavage guide groove 203 having a shape as shown in (d) is selected and formed at each intersection of the resonance plane line 201 and the secondary cleavage plane line 202.

  The length of the cleavage guide groove 203 in the direction parallel to the resonance surface line 201 and the interval at which the cleavage guide groove 203 is formed on the resonance surface line 201 are arbitrary, but need not be formed on the waveguide 204. Needless to say, there is.

  Next, the formation process of a waveguide and an electrode is demonstrated using FIG. 4 (a) and (b).

  As shown in FIG. 4A, a striped waveguide (ridge) 204 is formed in a direction perpendicular to the resonance plane line 201. The method for forming the waveguide 204 is the same as the method for forming the cleavage guide groove 203.

Next, as shown in FIG. 4B, an insulating film made of SiO ₂ is deposited on the entire surface of the substrate 101, the waveguide 204 and the insulating film on the side wall thereof are etched, and the p-GaN contact layer 108 is formed. A positive electrode 205 made of palladium (Pd) and platinum (Pt) is formed in the exposed region where the p-GaN contact layer 108 is exposed.

  In this embodiment, Pd and Pt are vapor-deposited on the p-GaN contact layer 108 to form the positive electrode 205. However, the positive electrode 205 is not limited to Pd and Pt, and is formed from other materials. Also good.

  Here, FIG. 5 shows a modification of the positive electrode 205.

As shown in FIG. 5, a positive electrode 205 having an uncovered region in the vicinity of the resonance surface line 201 may be formed. Shape irregularities such as electrode flash and peeling on the resonance surface due to the cleavage of the substrate mainly occur on the positive electrode, so that the positive electrode is not formed on the resonance surface so that the upper electrode of the positive electrode is in direct contact with the waveguide. It is known that when formed, there is almost no shape abnormality associated with the cleavage of the substrate. Therefore, as shown in FIG. 5, if the positive electrode 205 is not formed in the vicinity of the resonance plane line 201, it is possible to prevent the occurrence of flashing and peeling of the electrode due to cleavage. Further, when the region in the vicinity of the resonance surface 207 where the positive electrode 205 is not formed is covered with an insulating film such as SiO ₂ , the first upper electrode 206 Since it is in contact with the insulating film, adhesion is improved, and it is effective in preventing shape abnormality caused by cleavage. In addition, since no current is injected near the resonance surface 207 of the element, an effect of suppressing heat generation in the resonance surface line 201 accompanying the emission of laser light can be expected.

  The waveguide 204 may be formed as a buried type, for example, embedded in the crystal instead of the ridge type.

  Next, a process for forming the first upper electrode and the second upper electrode will be described with reference to FIGS.

  As shown in FIG. 6A, a first upper electrode 206 having a width wider than that of the positive electrode 205 is formed on the positive electrode 205. The first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the resonance surface vicinity region 207 of each semiconductor laser element so that the width in the same direction as the resonance surface line 201 is reduced. . In addition, the upper portion of the resonance surface line 201 is formed so as to cover the waveguide 204 and to have the minimum width. The resonance surface vicinity region 207 here is desirably a region of ± 50 μm or less in the direction along the waveguide 204 with the resonance surface line 201 as the center. If the region in which the width of the first upper electrode 206 is reduced is the resonance surface vicinity region 207 of ± 50 μm with the resonance surface line 201 as the center, the cleavage guide groove 203 having a width of 1 μm or more and 30 μm or less is also resonant. It is included in the surface vicinity region 207. For this reason, the cleavage is smoothly performed along the cleavage guide groove 203, and the cleavage can be performed with higher accuracy, so that the yield of the semiconductor laser device can be improved. Hereinafter, the reason will be described with reference to the drawings.

  FIG. 7 is an enlarged view of the periphery of one of the semiconductor laser elements shown in FIG.

  As shown in FIG. 7, the first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the respective resonance surface vicinity regions 207 at both ends in the waveguide 204 direction. The width in the vertical direction is reduced. That is, in the region 207 near one resonance plane, the first upper electrodes of the semiconductor laser elements adjacent to each other in the direction of the waveguide 204 reduce the width in the direction perpendicular to the waveguide 204 toward the resonance plane line 201. And formed to have a minimum width on the resonance plane line 201. For this reason, the stress exerted on the substrate 101 by the first upper electrode 206 is concentrated on the portion where the resonance plane line 201 and the waveguide 204 intersect. Further, the entire cleavage guide groove 203 centering on each resonance surface line 201 is formed so as to be included in the range in which the first upper electrode 206 reduces the width, so that the scribe line is introduced at the time of cleavage. When an external force is applied to the back surface of the wafer, the cleavage surface smoothly propagates from the cleavage guide groove 203 to the waveguide position where the stress is concentrated by the resonance surface line 201 to obtain a cleavage surface with high crystallinity. be able to.

  Further, the semiconductor laser element shown in FIG. 7 is different in the method of reducing the width of the first upper electrode 206 at both ends in the waveguide 204 direction. Therefore, in the stage before cleavage, the width of the first upper electrode 206 is different across one resonance surface, but the width in the direction perpendicular to the waveguide 204 is plane-symmetric about the waveguide. Since the shape remains unchanged, the stress exerted on the substrate by the first upper electrode 206 can be concentrated at the position of the waveguide 204 in the resonance plane line 201.

  FIG. 8 is a semiconductor laser device showing an example of the shape of the first upper electrode 206 for more efficiently obtaining a cleavage plane with excellent crystallinity.

  As shown in FIG. 8, the first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 as an axis in the respective resonance surface vicinity regions 207 at both ends in the waveguide 204 direction. Are formed in plane symmetry with the center line in the direction perpendicular to the axis as the axis, and the width in the direction perpendicular to the waveguide 204 is continuously reduced. In this way, in the region near the resonance surface 207, the first upper electrode 206 is formed in contrast with the adjacent semiconductor laser element as it is contrasted in the semiconductor laser element. The stress exerted on the substrate 101 can be concentrated at the intersection of the resonance plane line 201 and the waveguide 204, rather than being formed so as to have only symmetry about the axis. For this reason, in the cleavage step, the cleavage plane can be prevented from jumping from the periphery of the cleavage guide groove 203 to an orientation in which a crystal plane different from the intended crystal plane is exposed. A cleavage plane that smoothly propagates through the cleavage guide groove 203 can be obtained with higher accuracy.

  The first upper electrode 206 shown in FIG. 8 is formed in plane symmetry with the waveguide 204 as an axis, and is formed in plane symmetry with a center line in a direction perpendicular to the waveguide 204 as an axis. However, instead of using the center line in the direction perpendicular to the waveguide 204 as an axis, the first upper electrode 206 may be formed so as to have symmetry with the resonance plane line 201 as an axis. In the region near the resonance surface 207, the contrasting first upper electrode 206 is formed with the resonance surface line 201 and the waveguide 204 as axes. Therefore, the same effect can be obtained.

  When the first upper electrode 206 has a layout in which the width in the direction perpendicular to the waveguide 204 has the same minimum width in the resonance plane line 201, the resonances at both ends formed in the semiconductor laser element are obtained. The surface line 201 can be used as an exit surface or a reflection surface.

  Next, as shown in FIG. 6B, the second upper electrode 208 is formed on the first upper electrode 206. The second upper electrode 208 is a bonding pad electrode, and the first upper electrode 206 connects the second upper electrode 208 and the positive electrode 205. Next, the back surface of the substrate 101 is polished until the substrate 101 reaches about 100 μm, and a negative electrode is formed on the polished side. In the case of a substrate formed of a material that does not have conductivity, it is necessary to perform etching until the n-type layer is exposed from the surface side to form a negative electrode before polishing.

  Next, the cleavage process will be described. FIG. 9 is a diagram illustrating a substrate cleaving process.

  As shown in FIG. 9, by using a scriber, a very thin scribe line is put short at the end of the wafer resonance surface line 201, and an external force is applied from the back side using the scribe line as an introduction port. Are cleaved into a line of bars. At this time, if the first upper electrode 206 has a shape as provided by the present invention, a cleavage plane with high crystallinity can be obtained. The wafer cut into a bar shape is secondarily cleaved to cut chips.

  Here, the amount of deviation due to cleavage in the cleavage step will be described.

  FIG. 10A shows a shift amount due to cleavage of the semiconductor laser element having the first upper electrode shown in FIG. 8, and FIG. 10B shows cleavage of the semiconductor laser element having the first upper electrode shown in FIG. The amount of deviation due to is shown. The vertical axis indicates the amount of deviation due to cleavage, and the horizontal axis indicates the number of elements. The first upper electrode shown in FIG. 11 as a comparison is asymmetric with respect to the waveguide 204 and has a shape in which the width is discontinuously reduced in the region near the resonance surface 207.

  As shown in FIGS. 10A and 10B, in the semiconductor laser device having the first upper electrode according to the present embodiment, the amount of deviation due to cleavage is hardly seen, but as shown in FIG. In the cleavage of the semiconductor laser device having one upper electrode, it can be seen that the number of devices increases and the amount of deviation increases and the yield deteriorates.

  The steps after the cleavage step are omitted because they are not directly related to the present invention.

  Conventionally, in order to have an effect on the cleavage of the substrate, it has been necessary to perform processing on the substrate itself. However, the present invention forms the first upper electrode 206 in the region near the resonance surface 207 in a characteristic shape. As a result, a cleavage plane with high crystallinity can be obtained, and the characteristic yield of the semiconductor laser device can be improved. In the manufacture of a general semiconductor laser device, the first upper electrode is wide enough to cover almost the entire surface of the device and has a certain thickness, so that the influence of stress on the substrate is large. For this reason, in the present invention, by controlling the stress through the shape of the first upper electrode 206, the substrate can be cleaved with high accuracy and good reproducibility without complicating the processing of the substrate and the laminated structure. Can do. That is, according to the present invention, the cleavage accuracy can be greatly improved without complicating the diffusion process of the semiconductor laser element.

(First Modification of One Embodiment)
FIG. 12A shows a first modification of the present embodiment.

  As shown in FIG. 12A, in the first modification of the present embodiment, the first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the resonance surface vicinity region 207, and the resonance surface line. The width in the same direction as 201 is reduced, but the reduction is continuously changed, and then formed to have a certain minimum width, and is continuous at the resonance plane line 201. Thus, instead of continuously reducing the width toward the resonance surface line 201 as shown in the present embodiment, the shape of the first upper electrode 206 shown in FIG. Further, the structure has symmetry with respect to the waveguide 204, and the stress exerted on the substrate by the first upper electrode 206 is concentrated at the position of the waveguide 204 in the resonance plane line 201. A high cleavage plane can be obtained.

(Second Modification of One Embodiment)
FIG. 12B shows a second modification of the present embodiment.

  As shown in FIG. 12B, in the second modification of the present embodiment, the first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the resonance surface vicinity region 207, and the resonance surface line. Although the width in the same direction as 201 is reduced, the reduction does not continuously change toward the resonance surface line 201 but is reduced stepwise by a finite length multiple times. Yes. Thus, even the shape of the first upper electrode 206 shown in FIG. 12B has symmetry with the waveguide 204 as an axis, and the stress exerted on the substrate by the first upper electrode 206. Since the structure is concentrated at the position of the waveguide 204 in the resonance plane line 201, a cleavage plane with high crystallinity can be obtained.

  In the resonance surface vicinity region 207, when the width of the first upper electrode 206 is reduced stepwise, in order to enhance the effect of concentrating stress on the resonance surface line 201, the stepwise width reduction is performed as finely as possible. It is desirable that In the case where the first upper electrode 206 undergoes a large reduction such that the first upper electrode 206 becomes narrow at once in the resonance surface vicinity region 207, it is difficult to obtain the effect of stress concentration at the position of the waveguide 204 in the resonance surface line 201.

(Third Modification of One Embodiment)
FIG. 12C shows a third modification of the present embodiment.

  As shown in FIG. 12C, in the third modification of the present embodiment, the first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the resonance surface vicinity region 207, and the resonance surface line. The width in the same direction as 201 is reduced, and the resonance surface line 201 is formed to have a certain minimum width. As described above, in the present embodiment, when the minimum width of the first upper electrode 206 in the resonance surface line 201 has the same layout, it can be used as both the emission surface and the reflection surface. Street. In the third modification of the present embodiment, the shape to be reduced toward the resonance surface line 201 is mixed in a continuous manner and a stepwise manner. As described above, the stress exerted on the substrate by the first upper electrode 206 formed so as to have symmetry with respect to the waveguide 204 is concentrated at the position of the waveguide 204 in the resonance plane line 201. Therefore, a cleavage plane with high crystallinity can be obtained.

(Fourth modification of one embodiment)
FIG. 12D shows a fourth modification of the present embodiment.

  As shown in FIG. 12D, in the fourth modification example of the present embodiment, the first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the resonance surface vicinity region 207 as a resonance surface line. The width in the same direction as 201 is continuously reduced, has a certain minimum width in the vicinity of the resonance surface line 201, and is formed in plane symmetry with a center line in a direction perpendicular to the waveguide 204 as an axis. The shape shown in FIG. 12D is a structure in which the stress exerted on the substrate by the first upper electrode 206 is more concentrated at the position of the waveguide 204 in the resonance plane line 201 as in the modification of FIG. A cleaved surface with high crystallinity can be obtained.

(Fifth Modification of One Embodiment)
FIG. 12E shows a fifth modification of the present embodiment.

  As shown in FIG. 12E, in the fifth modification of the present embodiment, the first upper electrode 206 is formed in plane symmetry about the waveguide 204 in the resonance surface vicinity region 207, and the resonance surface line. The width in the same direction as 201 is continuously reduced, and the plane is symmetrical with respect to the resonance surface line 201 as an axis. As described above, in the shape shown in FIG. 12E, the stress exerted on the substrate by the first upper electrode 206 is more concentrated at the position of the waveguide 204 in the resonance plane line 201, as in the modification of FIG. Because of the structure, a cleavage plane with high crystallinity can be obtained.

  Although the first to fifth modifications have been shown, the present invention is configured such that the first upper electrode 206 is formed in plane symmetry with respect to the waveguide 204 in the resonance surface vicinity region 207 as the resonance surface line 201. Although the layout is such that the width in the same direction is reduced, the layout is not limited to the above-described modified example, but may be a layout having slopes or a mixture of slopes and stages. If at least the first upper electrode is formed in plane symmetry with respect to the waveguide 204 and the width in the same direction as the resonance surface line 201 is reduced, an effect of concentrating stress on the resonance surface can be expected.

  The semiconductor laser device according to the present invention can obtain a resonant surface with high crystallinity with good reproducibility without complicating the manufacturing process, and is useful for a semiconductor laser device, a manufacturing method thereof, and the like.

It is sectional drawing of the semiconductor laser element which concerns on one Embodiment of this invention. (A) And (b) is a top view of the manufacturing process of the semiconductor laser element concerning one Embodiment of this invention. It is a top view which shows typically the shape of the cleavage guide groove which concerns on one Embodiment of this invention. (A) And (b) is a top view of the manufacturing process of the waveguide and positive electrode of a semiconductor laser element concerning one embodiment of the present invention. It is a top view which shows the modification of the positive electrode which concerns on one Embodiment of this invention. (A) And (b) is a top view of the manufacturing process of the 1st and 2nd upper electrode of the semiconductor laser element concerning one Embodiment of this invention. It is a top view of the periphery of the semiconductor laser element which concerns on one Embodiment of this invention. It is a top view of the periphery of the semiconductor laser element which concerns on the other modification of one Embodiment of this invention. It is a figure which shows typically the cleaving process which concerns on one Embodiment of this invention. (A) And (b) is a graph which compares the amount of cleavage deviation by the shape of the 1st upper electrode. It is a top view which shows the shape of the 1st upper electrode for a comparison. (A)-(e) is a top view which shows the shape of the 1st upper electrode of each modification of one Embodiment of this invention.

Explanation of symbols

101 substrate 102 n-GaN layer _{103 n-Al a Ga 1-} a N (0 <a <1) cladding layer 104 n-GaN optical guide layer 105 multiple quantum well active layer 106 p-GaN optical guide layer 107 p-Al _b Ga _1-b N (0 <b <1) cladding layer 108 p-GaN contact layer 109 LD structure 201 resonant surface line 202 secondary cleavage surface line 203 cleavage guide groove 204 waveguide 205 positive electrode 206 first upper electrode 207 Resonant surface vicinity region 208 Second upper electrode

Claims (14)

An active layer including a light emitting portion on a substrate, a striped waveguide formed in the active layer, an electrode for supplying a current to the active layer, and an electrode electrically connected to the electrode A semiconductor laser device having an upper electrode connected to a pair of resonator surfaces facing each other in the waveguide,
The upper electrode is formed in plane symmetry with the waveguide as an axis in a region near the resonance surface, and the width in a direction perpendicular to the waveguide decreases as the resonance surface approaches the resonance surface. ,
Each of the resonance surfaces is cleaved along a cleavage guide groove formed in at least the active layer of the active layer and the substrate.   2. The semiconductor laser device according to claim 1, wherein the width of the upper electrode in the direction perpendicular to the waveguide is the smallest and the same at the end of each cleavage plane.   3. The semiconductor laser device according to claim 1, wherein the upper electrode is formed in plane symmetry with a center line in a direction perpendicular to the waveguide as an axis. 4.   4. The semiconductor laser device according to claim 1, wherein a width of the upper electrode in a direction perpendicular to the waveguide is continuously reduced. 5.   5. The semiconductor laser device according to claim 1, wherein a minimum width of the upper electrode in a direction perpendicular to the waveguide is larger than a width of the waveguide. 6.   6. The semiconductor laser device according to claim 1, wherein the electrode has a region that does not cover the waveguide at at least one end of each cleavage plane. 7.   7. The semiconductor laser device according to claim 1, wherein a bottom of the cleavage guide groove reaches the substrate. 7.   8. The semiconductor laser device according to claim 7, wherein a depth of the cleavage guide groove is 2 μm or more and 20 μm or less.   9. The semiconductor laser device according to claim 1, wherein a width of the cleavage guide groove in a direction parallel to the waveguide is 1 μm or more and 30 μm or less.   The planar shape of the cleavage guide groove is such that at least one end of the cleavage guide groove in a direction perpendicular to the waveguide is inclined with respect to the waveguide. The semiconductor laser device according to claim 1.   The semiconductor laser device according to claim 1, wherein the substrate is gallium nitride. A step (a) of forming an active layer including a light emitting portion on a substrate in a wafer state;
A step (b) of forming a cleavage guide groove in a region that assists in cleavage of the substrate and includes a cleavage plane, at least with respect to the active layer;
Forming a striped waveguide in the active layer (c);
Forming an electrode for supplying current to the active layer on the waveguide (d);
Forming an upper electrode connected to the electrode on the electrode (e);
Cleaving the substrate in the wafer state with the aid of the cleavage guide groove to form a resonance surface of the waveguide (f),
In the step (e), the upper electrode is planarly symmetric with respect to the waveguide in an area including the cleavage plane, and is reduced as the width in a direction perpendicular to the waveguide approaches the cleavage plane. A method of manufacturing a semiconductor laser device, characterized by comprising:   13. The step (e), wherein the upper electrode is formed in plane symmetry with a cleavage plane in a direction perpendicular to the waveguide as an axis in a region including the cleavage plane. Manufacturing method of semiconductor laser device.   In the step (b), the planar shape of the cleavage guide groove is formed such that an end of the cleavage guide groove in a direction perpendicular to the waveguide has a pointed portion with respect to the waveguide. A method for manufacturing a semiconductor laser device according to claim 12 or 13.

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