JP2020088182A - Semiconductor laser array device - Google Patents

Abstract

To provide a semiconductor laser array device having a plurality of light emitting parts capable of achieving reduction in warpage and high output.SOLUTION: A semiconductor laser array device 10 includes a substrate 101, and a laminate 100. The laminate 100 includes: a first semiconductor layer (an n-side clad layer 102) of a first conductivity type; an active layer 103; and a second semiconductor layer (a p-side clad layer 104 and a p-side contact layer 105) of a second conductivity type different from the first conductivity type. The laminate 100 has at least three light emitting parts 131 to 133. Between two light emitting parts adjacent to each other, groove parts 141, 142 dividing the laminate are formed. The groove parts 141, 142 extend from an upper surface to a lower surface of the laminate 100. The ratio of the capacity of the groove part 141 to the sum of the capacity of the groove part 141 and the volume of the laminate 100 between two groove pats 141, 142 adjacent to each other is 20% or more, and the distance between the centers of two adjacent light emitting parts is 200 μm or more.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a semiconductor laser array device.

Conventionally, as a watt class high-power laser light source, a monolithic semiconductor laser array device in which a laser array portion having a plurality of light emitting portions is formed on a single substrate is known. In such a semiconductor laser array device, by providing a groove between two adjacent light emitting portions, thermal interference between the light emitting portions can be suppressed and a high light output can be obtained.

For example, Patent Document 1 discloses a broad area laser including an epitaxial layered body in which a groove is formed, and one layer of the epitaxial layered body is partially removed by the groove. The broad area laser disclosed in Patent Document 1 will be briefly described below with reference to the drawings. FIG. 7 is a schematic cross-sectional view showing the configuration of the broad area laser 1001 disclosed in Patent Document 1.

As shown in FIG. 7, a broad area laser 1001 disclosed in Patent Document 1 includes an epitaxial layered body 1002 having a lower surface 1023 and an upper surface 1022, and the epitaxial layered body 1002 includes a beam generating active layer 1021. .. The epitaxial stacked body 1002 has a plurality of grooves 1003 along the direction from the upper surface 1022 to the lower surface 1023, and in the groove 1003, at least one layer of the epitaxial stacked body 1002 is partially removed. Since the upper surface of the epitaxial stacked body 1002 has a plurality of ridges 1004 and is in contact with each of the grooves 1003, the upper surface side of the epitaxial stacked body 1002 has a stripe shape. The maximum width d1 of the ridge 1004 and the maximum width d2 of the groove 1003 are 20 μm.

Further, on the upper surface 1022 of the epitaxial layered structure 1002, a dielectric passivation portion 1009 is arranged except for the upper portion of the ridge 1004 and is insulated and separated. Above the ridge 1004, respective terminals for supplying a current flowing to the light emitting portion are provided. Layer 1005 is disposed. As a result, laser light is emitted from the plurality of light emitting units located below the plurality of ridges 1004.

In the broad area laser 1001 disclosed in Patent Document 1, with this configuration, it is possible to solve the problem that the ridge 1004 is damaged by the “thermal lens effect” that narrows the laser mode of the laser light to several μm at a large current. I am trying. Further, in Patent Document 1, an attempt is made to provide a broad area laser capable of improving efficiency at high output and improving life.

Japanese Patent Publication No. 2013-501347

However, in the broad area laser 1001 disclosed in Patent Document 1, since the width d2 of the groove 1003 is limited to a maximum of 20 μm, when supplying a current capable of realizing an optical output of several tens of watts, the ridge is used. Thermal interference occurs between 1004. Therefore, the broad area laser 1001 disclosed in Patent Document 1 cannot realize high output.

Further, the broad area laser 1001 may be warped due to lattice mismatch of each layer in the epitaxial multilayer body 1002. When such a warp occurs, it becomes a big problem when combining laser beams from a plurality of light emitting units. In other words, the warp of the broad area laser 1001 causes the heights of the plurality of light emitting portions to shift. Due to this height shift, the coupling efficiency of the plurality of laser beams decreases when the laser beams from the plurality of light emitting units are condensed. Therefore, it becomes difficult to collect the light from the plurality of light emitting portions at one point.

The present disclosure solves such a problem, and an object of the present disclosure is to reduce warpage and achieve higher output in a semiconductor laser array device having a plurality of light emitting units.

In order to solve the above problems, an aspect of a semiconductor laser array device according to the present disclosure includes a substrate and a stacked body arranged above the substrate, and the stacked body is arranged above the substrate. A first semiconductor layer of a first conductivity type, an active layer disposed above the first semiconductor layer, and a second conductivity type second layer disposed above the active layer and different from the first conductivity type. A semiconductor layer, the stacked body is arranged along the active layer, each has at least three light emitting portions for emitting laser light, two of the at least three light emitting portions adjacent to each other. Grooves that divide the stacked body are formed between the light emitting portions, and the groove extends from an upper surface of the stacked body to a lower surface of the stacked body, and the stacked body between two adjacent grooved portions. The ratio of the volume of the groove to the sum of the volume of the body and the volume of the groove is 20% or more, and the distance between the centers of the two adjacent light emitting units is 200 μm or more.

As described above, the distance between the light emitting portions is 200 μm or more, so that the effect of thermal interference between the laser portions can be suppressed. As a result, the amount of current supplied to each light emitting unit can be increased, so that it is possible to increase the output of the semiconductor laser array device. Further, by forming a groove portion reaching the substrate between the light emitting portions, lattice mismatch strain can be divided. In addition, the warp of the semiconductor laser array device (that is, the substrate (Warp) can be significantly suppressed, and the amount of warp can be 5 μm or less. As a result, it is possible to prevent the coupling efficiency from decreasing due to the warp of the semiconductor laser array device when the laser light emitted from the plurality of light emitting units is condensed by the lens or the like.

Further, in one aspect of the semiconductor laser array device according to the present disclosure, the substrate may be gallium nitride, and the stacked body may include a gallium nitride-based material.

As described above, although a large warp may occur in the semiconductor laser array device including the gallium nitride-based material, the warp can be significantly reduced by forming the groove portion between the light emitting portions.

Further, in one aspect of the semiconductor laser array device according to the present disclosure, the three or more light emitting units may include four or more light emitting units.

The increase in the number of light emitting portions increases the width in the direction perpendicular to the resonance direction of the semiconductor laser array device (that is, the arrangement direction of the light emitting portions), which may increase the warp of the substrate. By disposing the groove portion and setting the volume of the groove portion to be 20% or more of the volume of the laminated body, the warpage amount can be 5 μm or less. As a result, it is possible to prevent the coupling efficiency from decreasing due to the warp of the semiconductor laser array device when the laser light emitted from the plurality of light emitting units is condensed by the lens or the like.

Further, in one aspect of the semiconductor laser array device according to the present disclosure, the groove may have a first groove and a second groove having a width narrower than the first groove and deeper than the first groove. Good.

As a result, the volume of the groove can be reduced as compared with the case where the groove having a constant width is formed, so that the amount of the laminated body or the substrate to be removed can be reduced and the reduction in strength of the semiconductor laser array device can be suppressed. Further, as compared with the case where only the first groove portion is formed, the lattice mismatch strain can be further divided, and the warpage amount can be further reduced.

Further, in one aspect of the semiconductor laser array device according to the present disclosure, the first groove portion may have a depth to the main surface of the substrate or the inside of the substrate.

As a result, the contact area between the stacked body and the substrate can be reduced, and a deep groove can be formed.

Further, in one aspect of the semiconductor laser array device according to the present disclosure, the first groove portion may have a depth to the inside of the first semiconductor layer.

Since the second groove portion reaching the substrate is provided as described above, the lattice mismatch strain can be divided even if the first groove portion does not reach the substrate.

According to the present disclosure, in a semiconductor laser array device having a plurality of light emitting units, it is possible to reduce warpage and increase output.

FIG. 1 is a schematic cross-sectional view showing the structure of the semiconductor laser array device according to the first embodiment. FIG. 2A is a graph showing the correlation between the ratio of the volume of the groove portion in the semiconductor laser array device and the warp amount of the semiconductor laser array device. FIG. 2B is a graph showing the correlation between the ratio of the volume of the groove in the semiconductor laser array device and the amount of warpage of the semiconductor laser array device 10 separately for each factor of warpage. FIG. 3 is a diagram schematically showing the warpage amount of the conventional semiconductor laser array device and the semiconductor laser array device according to the present embodiment. FIG. 4A is a schematic cross-sectional view showing each step of the first half of the method for manufacturing the semiconductor laser array device according to the first embodiment. FIG. 4B is a schematic cross-sectional view showing each step in the latter half of the method for manufacturing the semiconductor laser array device according to the first embodiment. FIG. 5 is a schematic cross-sectional view showing the structure of the semiconductor laser array device according to the second embodiment. FIG. 6 is a schematic sectional view showing the structure of the semiconductor laser array device according to the third embodiment. FIG. 7 is a schematic cross-sectional view showing the configuration of the broad area laser disclosed in Patent Document 1.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that each of the embodiments described below shows a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, constituent elements, and the arrangement positions and connection forms of the constituent elements shown in the following embodiments are merely examples and do not limit the present disclosure. Therefore, among the constituent elements in the following embodiments, the constituent elements that are not described in the independent claims showing the highest concept of the present disclosure will be described as arbitrary constituent elements.

In addition, each drawing is a schematic diagram and is not necessarily strictly illustrated. Therefore, the scales and the like do not necessarily match in each drawing. In each drawing, the substantially same components are designated by the same reference numerals, and overlapping description will be omitted or simplified.

Further, in the present specification, the terms “upper” and “lower” do not refer to an upward direction (vertical upward) and a downward direction (vertical downward) in absolute space recognition, but are based on a stacking order in a stacked structure. Is used as a term defined by a relative positional relationship with. Also, the terms "upper" and "lower" refer to not only two components being spaced apart from each other and another component being present between the two components, but also two components. It also applies when they are placed in contact with each other.

(Embodiment 1)
The semiconductor laser array device according to the first embodiment will be described.

[1-1. Construction]
First, the structure of the semiconductor laser array device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the structure of a semiconductor laser array device 10 according to this embodiment. FIG. 1 shows a cross section perpendicular to the resonance direction of the laser light of the semiconductor laser array device 10.

The semiconductor laser array device 10 according to the present embodiment is a laser array element having at least three light emitting units 131, 132 and 133. In the present embodiment, the semiconductor laser array device 10 emits laser light included in a wavelength band corresponding to blue-violet light to blue light, and is used as a light source for laser processing, for example. The application of the semiconductor laser array device is not limited to laser processing. The semiconductor laser array device may be used in, for example, a laser display, a laser printer, a projector, or the like.

As shown in FIG. 1, the semiconductor laser array device 10 includes a substrate 101 and a stacked body 100 arranged above the substrate 101. In this embodiment, the semiconductor laser array device 10 further includes an insulating layer 106, a p electrode 107, a pad electrode 108, and an n electrode 109. Although not shown, the semiconductor laser array device 10 includes reflecting surfaces forming a resonator on both end faces in the resonance direction of the laser light.

The stacked body 100 includes a first semiconductor layer of the first conductivity type disposed above the substrate 101, an active layer 103 disposed above the first semiconductor layer, and a first semiconductor layer disposed above the active layer 103. The semiconductor layer has a second semiconductor layer of a second conductivity type different from the first conductivity type.

The stacked body 100 has at least three light emitting portions that are arranged along the active layer 103 and that each emit laser light. In the present embodiment, the semiconductor laser array device 10 has three light emitting units 131, 132 and 133. The number of light emitting units may be three or more, and may be appropriately determined according to the optical output required of the semiconductor laser array device 10. The center-to-center distance Dc of two adjacent light emitting portions of the three light emitting portions 131, 132, and 133 is 200 μm or more.

Grooves 141 and 142 that divide the stacked body 100 are formed between two adjacent light emitting units among at least three light emitting units. In this embodiment, a groove 141 is formed between the light emitting portion 131 and the light emitting portion 132, and a groove 142 is formed between the light emitting portion 132 and the light emitting portion 133. Each of the groove portions 141 and 142 is continuously formed between both end faces of the stacked body 100 in the resonance direction. As a result, the stacked body 100 is separated into the first laser section 121, the second laser section 122, and the third laser section 123 by the groove sections 141 and 142. The first laser section 121, the second laser section 122, and the third laser section 123 form a laser array.

The groove portions 141 and 142 extend from the main surface of the stacked body 100 farther from the substrate 101 to the main surface nearer to the substrate 101. In other words, the grooves 141 and 142 extend from the upper surface of the stacked body 100 to the lower surface thereof. Further, the ratio of the volume of each of the groove portions 141 and 142 to the volume between two adjacent groove portions 141 and 142 of the stacked body 100 is 20% or more. The volumes of the grooves 141 and 142 are defined as the volumes of the portions of the grooves 141 and 142 above the main surface on which the stacked body 100 of the substrate 101 is stacked. Further, the width of the groove portion 141 (dimension in the horizontal direction in FIG. 1) is defined by the distance between the side surfaces of the stacked body 100. Therefore, the portion where the insulating layer 106 formed in the groove portions 141 and 142 is also a part of the groove portions 141 and 142.

Each of the first laser unit 121 to the third laser unit 123 includes a ridge portion 125 that is injected with a current and emits laser light, and a support portion 126 arranged along the ridge portion 125. The ridge portion 125 and the support portion 126 are separated by the separation groove 127.

The substrate 101 is a base material of the semiconductor laser array device 10. In this embodiment, the substrate 101 is a gallium nitride (GaN) substrate having a thickness of 100 μm. The thickness of the substrate 101 is not limited to 100 μm, and may be, for example, 50 μm or more and 120 μm or less.

The first semiconductor layer is a semiconductor layer of the first conductivity type and is arranged above the substrate 101. In the present embodiment, the first semiconductor layer includes the n-side cladding layer 102.

In the present embodiment, the n-side cladding layer 102 is a layer made of n-Al _0.2 Ga _0.8 N having a thickness of 3 μm. The configuration of the n-side cladding layer 102 is not limited to this. The thickness of the n-side cladding layer 102 may be 0.5 μm or more and 4.0 μm or less, and the composition may be n-Al _x Ga _1-x N (0<x<1).

The active layer 103 is a light emitting layer arranged above the first semiconductor layer. In the present embodiment, the active layer 103 is a quantum well active layer in which a well layer of In _0.18 Ga _0.82 N having a thickness of 5 nm and a barrier layer of GaN having a thickness of 10 nm are alternately stacked. Yes, it has two well layers. By including such an active layer 103, the semiconductor laser array device 10 can emit blue laser light having a wavelength of about 450 nm. The structure of the active layer 103 is not limited to this, and includes a well layer made of In _x Ga _1-x N (0<x<1) and Al _x In _y Ga _1-x-y N (0≦x+y≦1). The number of well layers is not limited to two, and the same effect can be obtained with one layer or three or more layers. Also, the same effect can be obtained in the wavelength band of 400 nm to 450 nm, that is, in the wavelength band of blue-violet light to blue light. The active layer 103 may include a guide layer formed on at least one of above and below the quantum well active layer. A region of the active layer 103 that serves as a current path, that is, a region below the ridge portion 125 emits light. Therefore, a region below the ridge 125 on the side surface of the active layer 103 at the front end facet of the resonator forms a light emitting portion.

The second semiconductor layer is a semiconductor layer of a second conductivity type different from the first conductivity type, and is arranged above the active layer 103. In this embodiment, the second semiconductor layer includes the p-side cladding layer 104 and the p-side contact layer 105.

The second semiconductor layer (that is, the p-side cladding layer 104 and the p-side contact layer 105) includes a plurality of ridge portions 125 that serve as current passages, and support portions 126 that are arranged on both sides of the ridge portion 125 and do not serve as current passages. Prepare By providing such a support portion 126, it is possible to reduce the stress generated by the concentration of the load on the ridge portion 125 when the semiconductor laser array device 10 is mounted in the junction-down manner.

In the present embodiment, the width of the ridge portion 125 is 20 μm. The width of the ridge portion 125 is not limited to this, and may be, for example, 5 μm or more and 50 μm or less.

The height of the upper surface of the support portion 126 from the substrate 101 is equal to the height of the upper surface of the ridge portion 125 from the substrate 101. As a result, when the semiconductor laser array device 10 is mounted in the junction-down manner, the stress caused by the concentration of the load on the ridge portion 125 can be reduced more reliably. Note that, here, the heights from the substrate 101 to the upper surface of the support portion 126 and the height from the substrate 101 to the upper surface of the ridge portion 125 are equal to each other in the configuration described above. In addition to the above configuration, a configuration in which these heights are substantially equal is also included. For example, a configuration in which these heights have an error of about 10% or less of the thickness of the second semiconductor layer is also included.

In the present embodiment, the width of support portion 126 (width in the horizontal direction in FIG. 1) is 70 μm. The width of the support portion 126 is not limited to this, and may be 30 μm or more and 200 μm or less. By setting the width to 30 μm or more, it is possible to reliably reduce the stress generated in the ridge portion 125 when the semiconductor laser array device 10 is mounted in the junction down manner. Further, by setting the width to 200 μm or less, the distance between the adjacent light emitting units can be reduced, so that the coupling of the laser light output from the plurality of light emitting units can be facilitated.

A separation groove 127 that separates the ridge portion 125 and the support portion 126 is formed in the second semiconductor layer. The separation groove 127 can confine current and light in the ridge portion 125. In the present embodiment, the width and depth of the separation groove 127 are 10 μm and 1 μm, respectively. The configuration of the separation groove 127 is not limited to this. The width of the separation groove 127 may be 5 μm or more and 30 μm or less. In addition, the depth of the separation groove 127 may be 0.4 μm or more, and may be a depth that does not reach the active layer 103 which is the light emitting portion. When the thickness of the second semiconductor layer is larger than 2.0 μm, the depth of the separation groove 127 may be 2.0 μm or less.

The p-side clad layer 104 is a clad layer included in the second semiconductor layer, and in the present embodiment, a p-Al _0.2 Ga _0.8 N layer having a thickness of 3 nm and a GaN layer having a thickness of 3 nm. It is a superlattice layer having a thickness of 0.6 μm, in which 100 layers each having 3 nm layers are alternately laminated. The configuration of the p-side cladding layer 104 is not limited to this. The thickness of the p-side cladding layer 104 may be 0.3 μm or more and 1 μm or less, and the composition thereof may be p-Al _x Ga _1-x N (0<x<1).

The p-side contact layer 105 is a contact layer included in the second semiconductor layer and arranged above the p-side cladding layer 104. In the present embodiment, the p-side contact layer 105 is a layer made of p-GaN having a thickness of 10 nm. The configuration of the p-side contact layer 105 is not limited to this. The p-side contact layer 105 may have a thickness of 5 nm or more and 0.5 μm or less.

The insulating layer 106 is a layer that insulates between the pad electrode 108 arranged above the second semiconductor layer and the second semiconductor layer. The insulating layer 106 is also arranged in the groove portions 141 and 142 and the separation groove 127. In addition, the insulating layer 106 has an opening above the ridge portion 125 for contacting the p-side contact layer 105 and the p-electrode 107. Note that the opening of the insulating layer 106 may have a slit shape. In this embodiment, the insulating layer 106 is a layer of SiO ₂ having a thickness of 200 nm. Note that the structure of the insulating layer 106 is not limited to this. The thickness of the insulating layer 106 may be 100 nm or more and 500 nm or less.

The p-electrode 107 is an electrode that is disposed above the p-side contact layer 105 and is in ohmic contact with the p-side contact layer 105. The p-electrode 107 is arranged above the ridge portion 125. That is, the p-electrode 107 is arranged in the opening of the insulating layer 106. The p-electrode 107 may be arranged above the insulating layer 106. The p-electrode 107 contacts the p-side contact layer 105 at the opening of the insulating layer 106. In the present embodiment, the p-electrode 107 is a laminated film in which Pd and Pt are laminated in order from the p-side contact layer 105 side. The configuration of the p-electrode 107 is not limited to this. The p-electrode 107 may be, for example, a single layer film or a multilayer film formed of at least one of Cr, Ti, Ni, Pd, Pt and Au.

The pad electrode 108 is a pad-shaped electrode arranged above the p-electrode 107. In the present embodiment, the pad electrode 108 is a laminated film in which Ti and Au are laminated in order from the p electrode 107 side, and is arranged above the ridge portion 125, the support portion 126, and the separation groove 127. The pad electrode 108 may also be arranged above the groove portions 141 and 142. Furthermore, the structure of the pad electrode 108 is not limited to this. The pad electrode 108 may be, for example, a laminated film of Ti, Pt and Au, Ni and Au, or the like.

The n-electrode 109 is an electrode arranged below the substrate 101. In the present embodiment, the n-electrode 109 is a laminated film in which Ti, Pt and Au are laminated in order from the substrate 101 side. The structure of the n-electrode 109 is not limited to this. The n-electrode 109 may be made of another conductive material.

[1-2. Action and effect]
The operation and effect of the semiconductor laser array device 10 according to the present embodiment will be described with reference to FIGS. 1, 2A and 2B.

First, FIG. 2A will be described. FIG. 2A is a graph showing the correlation between the ratio of the volume of the groove portion in the semiconductor laser array device 10 and the warp amount of the semiconductor laser array device 10. The curve shown in FIG. 2A is a graph obtained by fitting actual measurement data indicated by black circles.

Here, the ratio of the volume of the groove portion means the ratio of the volume of the groove portion to the sum of the volume of the laminated body between two adjacent groove portions and the volume of the groove portion. The volume of the groove means the volume of the portion of the groove above the main surface on which the stacked body 100 of the substrate 101 is stacked. In the graph shown in FIG. 2A, the horizontal axis represents the ratio and the vertical axis represents the warp amount of the semiconductor laser array device 10. In the present embodiment, the ratio is approximately equal to the ratio represented by the following equation (1) using the width A1 of the groove portion 141 and the width A2 of the second laser portion 122 in FIG.

(A1/(A1+A2)) (1)

Although the width of the groove 141 is used as the width A1, the width of the groove 142 may be used. Similarly, although the width A2 is the width of the second laser section 122, the width of the first laser section 121 or the third laser section 123 may be used.

As shown in FIG. 2A, the warp amount of the semiconductor laser array device 10 decreases as the ratio shown by the equation (1) increases. The reason for this is that the ratio shown by the equation (1) increases, and the ratio of the contact area between the substrate 101 made of GaN and the n-side cladding layer 102 made of AlGaN to the total area of the main surface of the substrate 101 decreases. This is because it is possible to suppress the lattice mismatch strain caused by the contact of materials having different lattice constants. Further, the lattice mismatch strain has a property of increasing as the thickness of the laminated film having a lattice constant different from that of the substrate 101 increases. Therefore, in order to reduce the lattice mismatch strain, it is important to reduce the ratio of the contact area between the substrate 101 and the laminated body 100 and to reduce the number of laminated films having different lattice constants.

Here, FIG. 2B will be described. FIG. 2B is a graph showing the correlation between the ratio of the volume of the groove portion in the semiconductor laser array device 10 and the warp amount of the semiconductor laser array device 10 separately for each warp factor.

The solid line curve shown in FIG. 2B is the same curve as the curve shown in FIG. 2A, and shows the correlation between the ratio of the volume of the groove portion in the semiconductor laser array device 10 and the warp amount of the semiconductor laser array device. In FIG. 2B, the warpage amount is shown separately for each of the two factors of the above-described lattice mismatch strain. The graph indicated by the alternate long and short dash line in FIG. 2B shows the amount of warpage due to the interface strain between the substrate 101 and the stacked body 100 (that is, the interface strain between GaN and AlGaN). That is, the graph indicated by the alternate long and short dash line shows, of the two factors of the above-mentioned warpage, “the ratio of the contact area between the substrate 101 made of GaN and the n-side cladding layer 102 made of AlGaN to the total area of the main surface of the substrate 101. Is equivalent to

On the other hand, the graph shown by the broken line in FIG. 2B shows the amount of warpage due to the strain that is increased by vertically stacking a laminated film made of AlGaN or the like on a substrate made of GaN or the like. That is, the graph indicated by the broken line has a characteristic that, among the two factors of the warp described above, “the substrate 101 and the laminated film having a different lattice constant from that of the substrate 101 laminated on the substrate 101 become thicker as they become thicker. It corresponds to the "I am doing" part.

In the range of the volume of the groove portion from about 0% to about 40%, the factor indicated by the broken line in FIG. 2B is dominant, and by increasing the ratio from 0%, it is possible to significantly reduce the warpage. On the other hand, in the range where the ratio is about 40% or more and less than 100%, the factor (see the broken line in FIG. 2B) caused by the contact between the substrate 101 and the stacked body 100 becomes dominant. As described above, the curve described in FIG. 2A is considered to be a curve determined based on two factors.

As described above, the warp amount of the semiconductor laser array device 10 is caused by the large lattice mismatch strain. Therefore, the amount of warpage can be suppressed by reducing the ratio of the contact area between the substrate 101 and the n-side cladding layer 102 of the first semiconductor layer and increasing the volume of the groove. Therefore, in the groove portions 141 and 142, removing all the first semiconductor layer and the second semiconductor layer having a large lattice mismatch strain with respect to the substrate 101 leads to a great reduction in strain amount, that is, warpage amount. .. In the semiconductor laser array device 10 according to the present embodiment, the warp amount can be 5 μm or less by setting the volume ratio of the groove portion to 20% or more.

Here, the effect of suppressing the warp amount of the semiconductor laser array device 10 will be described with reference to FIG. FIG. 3 is a diagram schematically showing the warp amount of the semiconductor laser array device 1010 of the related art and the semiconductor laser array device 10 according to the present embodiment. In FIG. 3, the light emitting end face of each semiconductor laser array device is shown. As shown in FIG. 3, in the conventional semiconductor laser array device 1010, warpage occurs. For example, when the warp amount is 5 μm or more, the laser light emitted from the light emitting portion 1132 near the center and the light emitting portions 1131 and 1133 at the end of the three or more light emitting portions 1131 to 1133 is perpendicular to the main surface of the substrate. The difference in position in different directions increases. As a result, when the laser light is condensed using, for example, a lens, the coupling efficiency of the laser light is reduced, so that a high optical output cannot be realized.

On the other hand, the volume ratio of the groove portions 141 and 142 of the semiconductor laser array device 10 according to the present embodiment is set to 20% or more of the volume of each of the first laser portion 121, the second laser portion 122 and the third laser portion 123. As a result, the amount of warpage in the semiconductor laser array device 10 can be reduced. Particularly, in the semiconductor laser array device 10 according to the present embodiment, the substrate 101 is GaN and the stacked body 100 contains a gallium nitride based material. As described above, the semiconductor laser array device 10 including the gallium nitride-based material may have a large warp. That is, as shown in FIG. 2A, in the semiconductor laser array device 10, due to the lattice mismatch strain caused by the difference in lattice constant between the substrate 101 made of GaN and the stacked body 100 made of AlGaInN-based material, and the difference in thermal expansion coefficient. Warpage may occur. However, in the semiconductor laser array device 10 according to the present embodiment, the warp amount can be set to 5 μm or less by including the above configuration.

Specifically, since the width of the ridge portion 125 is 20 μm, the width of the support portion 126 is 70 μm, and the width of the separation groove 127 is 10 μm, the width A2 of the first laser portion 121 is 180 μm. Is. In addition, as described above, the width of the first laser unit 121 may be 100 μm or more and 400 μm or less. Further, the second laser section 122 and the third laser section 123 have the same width as that of the first laser section, but it is possible to obtain the same effect even if there is a difference in width.

Further, in the present embodiment, the widths A1 of the groove portions 141 and 142 are the same width and are 80 μm. There is no problem if the depth is lower than the upper surface of the substrate 101 (that is, the surface on which the stacked body 100 is stacked). The widths A2 of the grooves 141 and 142 may not be the same, and the width A2 is not limited to this and may be, for example, 20 μm or more and 150 μm or less. Further, since the groove reaching the substrate 101 is formed, the volume ratio may be considered to be synonymous with the ratio represented by the formula (1). In the present embodiment, the ratio is about 30%, which is 20% or more, so that the warp amount can be 5 μm or less as shown in FIG. 2A. This makes it possible to suppress a decrease in coupling efficiency of laser light when collecting laser light emitted from the plurality of light emitting units.

In the present embodiment, the depth of the portion of the substrate 101 of the grooves 141 and 142 is about 1 μm, but the depth is not limited to this. The depth may be 1.0 μm or more. As a result, the above effect can be reliably exhibited. The depth may be smaller than the thickness of the substrate 101 by 20 μm or more. Since the thickness of the substrate 101 is usually 50 μm or more and 120 μm or less, the depth may be 100 μm or less. This ensures the strength of the substrate 101.

Further, the semiconductor laser array device 10 according to the present embodiment is provided with the groove portion 141 between the first laser portion 121 and the second laser portion 122 which are the adjacent light emitting portions, and the ridge portion 125 of each of them. The interval (that is, the center-to-center distance) is 260 μm in this embodiment. That is, the center-to-center distance Dc between the adjacent light emitting units is 260 nm. The distance is not limited to this, and may be 200 μm or more and 500 μm or less.

Since the center-to-center distance Dc of the adjacent ridge portions 125, that is, the adjacent light emitting portions is 200 μm or more, the effect of thermal interference between the plurality of light emitting portions can be suppressed, and the direction toward the substrate 101 can be suppressed. Since the diffusion of heat can be promoted, the output of the semiconductor laser array device 10 can be increased. Further, by setting the center-to-center distance Dc of the adjacent light emitting units to be 500 μm or less, it is possible to reduce the distance of the laser light emitted from the plurality of light emitting units. It is possible to suppress the reduction of the coupling efficiency of the laser light when collecting the light.

[1-3. Production method]
A method of manufacturing the semiconductor laser array device 10 according to the present embodiment will be described with reference to the drawings. 4A and 4B are schematic cross-sectional views showing each step of the method for manufacturing the semiconductor laser array device 10 according to the present embodiment. 4A and 4B, a cross section of the semiconductor laser array device 10 similar to that of FIG. 1 is shown.

As shown in the cross-sectional view (a) of FIG. 4A, first, the substrate 101 is prepared, and the first semiconductor layer, the active layer 103, and the second semiconductor layer are sequentially stacked. In this embodiment mode, the n-side cladding layer 102, the active layer 103, the p-side cladding layer 104, and the p-side contact layer 105 are sequentially stacked on the substrate 101. In this embodiment mode, each layer is formed by a metal organic chemical vapor deposition method (MOCVD).

Next, as shown in the sectional view (b) of FIG. 4A, groove portions 141 and 142 are formed. Specifically, first, the groove portions 141 and 142 are formed by a wet etching method, a dry etching method, or the like at positions corresponding to approximately the middle of the adjacent light emitting portions. The groove portions 141 and 142 are formed continuously along the resonance direction of the semiconductor laser array device 10, that is, without interruption.

Next, as shown in the sectional view (c) of FIG. 4A, the separation groove 127 is formed by a wet etching method, a dry etching method, or the like. Two separation grooves 127 are formed between the groove portions 141 and 142. A portion of the second semiconductor layer (in this embodiment, the p-side cladding layer 104 and the p-side contact layer 105) between the two separation grooves 127 becomes a ridge portion 125, and the separation groove 127 and the groove portions 141 and 142 are formed. The portion between and becomes the support portion 126.

Next, as shown in the sectional view (d) of FIG. 4A, the insulating layer 106 is formed by the plasma CVD method or the like. The insulating layer 106 is formed on the entire upper surface of the substrate 101, that is, the second semiconductor layer, the separation groove 127, and the groove portions 141 and 142.

Next, as shown in the cross-sectional view (e) of FIG. 4B, an opening is formed in the insulating layer 106, and the p electrode 107 is formed in the opening. First, an opening is formed by removing a portion of the insulating layer 106 above the ridge portion 125 by a wet etching method or the like. As a result, the p-side contact layer 105 is exposed in the opening. Then, the p-electrode 107 is formed on the p-side contact layer 105 in the opening by a vacuum deposition method or the like. The p electrode 107 may be formed above the insulating layer 106.

Next, as shown in the sectional view (f) of FIG. 4B, the pad electrode 108 is formed above the second semiconductor layer by a vacuum deposition method or the like. In the present embodiment, the pad electrode 108 is formed on the ridge portion 125 so as to cover the p electrode 107. Note that the pad electrode 108 may also be formed above the separation groove 127 and the support portion 126 as shown in the sectional view (f) of FIG. 4B.

Next, as shown in the cross-sectional view (g) of FIG. 4B, the n-electrode 109 is formed on the lower surface of the substrate 101 (that is, the surface on the back side of the surface on which the stacked body 100 is stacked) by a vacuum deposition method or the like. Form. The n-electrode 109 is formed on almost the entire lower surface of the substrate 101, but may be formed only at a position corresponding to the back side of the ridge portion 125.

Next, the end faces of the resonator are formed by cleavage to form a laser resonator. In the present embodiment, the cleavage is performed so that the resonator length is 1.2 mm, but the resonator length is not limited to this and may be, for example, 0.8 mm or more and 4 mm or less.

A reflective film such as a dielectric multilayer film may be formed on the end face of the resonator.

Although the semiconductor laser array device according to this embodiment includes three light emitting portions, the semiconductor laser array device may include four or more light emitting portions and three or more groove portions. As the number of light emitting portions increases in this way, the width of the semiconductor laser array device 10 in the direction perpendicular to the resonance direction (that is, the arrangement direction of the light emitting portions) becomes longer, so that the warpage of the substrate 101 increases. However, it is possible to set the warpage amount to 5 μm or less by disposing the groove portion between the light emitting portions and setting the volume of the groove portion to be 20% or more of the volume of the laminate. For example, in order to realize higher light output, the semiconductor laser array device may have 20 light emitting units.

In the semiconductor laser array device according to the present embodiment, the example in which the GaN-based material is used as the semiconductor laser array device has been described above, but the material used for the semiconductor laser array device according to the present embodiment is not limited to this. It is not limited, and may be AlGaInP, GaAs, GaAs/InP, or the like.

The material forming the substrate 101 is not limited to GaN single crystal, but may be sapphire, SiC, or the like.

(Embodiment 2)
A semiconductor laser array device according to the second embodiment will be described. The semiconductor laser array device according to the present embodiment differs from the semiconductor laser array device 10 according to the first embodiment in the structure of the groove. The semiconductor laser array device according to the present embodiment will be described below with reference to FIG. 5 focusing on the differences from the semiconductor laser array device 10 according to the first embodiment.

FIG. 5 is a schematic sectional view showing the structure of the semiconductor laser array device 20 according to the present embodiment.

As shown in FIG. 5, the semiconductor laser array device 20 according to the present exemplary embodiment has three light emitting units 131 to 133 and has three light emitting regions like the semiconductor laser array device 10 according to the first exemplary embodiment. Grooves 241 and 242 that divide the stacked body 100 are formed between two adjacent light emitting portions of the portions 131 to 133.

Further, the groove portion 241 according to the present embodiment has a first groove portion 241a and a second groove portion 241b having a width narrower than that of the first groove portion 241a and deeper than the first groove portion 241a. Similarly to the groove 241, the groove 242 has a first groove 242a and a second groove 242b having a width narrower than that of the first groove 242a and deeper than the first groove 242a.

As a result, the volume of the groove can be reduced as compared with the case where the groove having a constant width is formed, so that the amount of the stacked body or the substrate to be removed can be reduced and the strength reduction of the semiconductor laser array device 20 can be suppressed. Further, as compared with the case where only the first groove portions 241a and 242a are formed, the lattice mismatch strain can be further divided, and the warpage amount can be further reduced.

Further, in the present embodiment, the first groove portions 241a and 242a have a depth to the main surface of the substrate 101 (that is, the surface on which the stacked body 100 is stacked) or the inside of the substrate 101.

Thereby, the contact area between the stacked body 100 and the substrate 101 can be reduced, and the deep groove portions 241 and 242 can be formed.

The method of manufacturing the semiconductor laser array device 20 according to the present embodiment is different from the method of manufacturing the semiconductor laser array device 10 according to the first embodiment in the step of forming the groove portions 241 and 242.

In the process of forming the grooves 241 and 242 of the semiconductor laser array device 20 according to the present embodiment, first, the first grooves 241a and 242a are formed at positions corresponding to approximately the middle of the adjacent light emitting parts by a wet etching method, a dry etching method, or the like. Formed by. The first groove portions 241a and 242a are formed continuously along the resonance direction of the semiconductor laser array device 20, that is, without interruption. Subsequently, second groove portions 241b and 242b are formed on the bottom surfaces of the first groove portions 241a and 242a by a wet etching method, a dry etching method, or the like, respectively. By forming the second groove portions 241b and 242b on the bottom surfaces of the first groove portions 241a and 242a, the etching amount required to form the groove portions can be reduced as compared with the case where the groove portions having a constant width are formed from the upper surface of the second semiconductor layer.

Through the steps described above, the groove portions 241 and 242 of the semiconductor laser array device 20 according to this embodiment can be formed. The second groove portions 241b and 242b may be formed before the insulating layer 106 and the like are laminated, similarly to the formation of the groove portions 141 and 142 according to the first embodiment. The second groove portions 241b and 242b may be formed by using a laser scribing device or the like after forming the pad electrode 108 and the n electrode 109.

(Embodiment 3)
A semiconductor laser array device according to the third embodiment will be described. The semiconductor laser array device according to the present embodiment is different from the semiconductor laser array device 20 according to the second embodiment mainly in the configuration of the first groove portion. The semiconductor laser array device according to the present embodiment will be described below with reference to FIG. 6 focusing on the differences from the semiconductor laser array device 20 according to the second embodiment.

FIG. 6 is a schematic sectional view showing the structure of the semiconductor laser array device 30 according to the present embodiment.

As shown in FIG. 6, the semiconductor laser array device 30 according to the present embodiment has three light emitting units 131 to 133, and has three light emitting parts, like the semiconductor laser array device 20 according to the second embodiment. Grooves 341 and 342 that divide the stacked body 100 are formed between two adjacent light emitting units of the units 131 to 133.

Further, the groove portion 341 according to the present embodiment has a first groove portion 341a and a second groove portion 341b having a width narrower than the first groove portion 341a and deeper than the first groove portion 341a. Similarly to the groove portion 341, the groove portion 342 also has a first groove portion 342a and a second groove portion 342b having a width narrower than the first groove portion 342a and deeper than the first groove portion 342a.

As a result, the volume of the groove can be reduced as compared with the case where the groove having a constant width is formed, so that the amount of the laminated body or the substrate to be removed can be reduced and the decrease in strength of the semiconductor laser array device 30 can be suppressed. Further, as compared with the case where only the first groove portions 341a and 342a are formed, the lattice mismatch strain can be further divided and the warpage amount can be further reduced.

In addition, in the present embodiment, the first groove portions 341a and 342a have a depth to the inside of the first semiconductor layer, that is, the n-side cladding layer 102.

As a result, the etching amount of the substrate 101 can be reduced, so that the reduction in strength of the semiconductor laser array device 30 can be further suppressed.

In the present embodiment, the volume of the groove portions 341 and 342 is larger than the volume of the first groove portions 341a and 342a and the volume of the second groove portions 341b and 342b from the main surface on which the stacked body 100 of the substrate 101 is laminated. Defined as the sum of the upper part.

The method of manufacturing the semiconductor laser array device 30 according to the present embodiment is different from the method of manufacturing the semiconductor laser array device 20 according to the second embodiment in the step of forming the first groove portions 341a and 342a. Also in this embodiment, the first groove portions 341a and 342a are formed by a wet etching method, a dry etching method, or the like, similarly to the second embodiment. However, in the present embodiment, the etching depth is adjusted so that the first groove portions 341a and 342a have a depth to the inside of the first semiconductor layer.

Through the above steps, the first groove portions 341a and 342a of the semiconductor laser array device 30 according to the present embodiment can be formed.

(Modifications, etc.)
The semiconductor laser array device according to the present disclosure has been described above based on each embodiment, but the present disclosure is not limited to each of the above embodiments.

For example, in each of the above embodiments, the laminated body 100 is not limited to the configuration of each of the above embodiments. For example, a buffer layer or the like may be arranged between the substrate 101 and the n-side clad layer 102, or an electron barrier layer or the like may be arranged between the p-side clad layer 104 and the active layer 103.

Further, in each of the above embodiments, each laser unit has the support unit 126, but the support unit 126 may not be provided. Further, although each laser portion has the ridge portion 125, it may have a current confinement structure such as an electrode stripe structure or a buried type structure other than the ridge structure.

Further, it is realized by making various modifications to the above-described embodiments that can be thought of by those skilled in the art, or by arbitrarily combining the components and functions of the above-described embodiments without departing from the spirit of the present disclosure. Such forms are also included in the present disclosure.

The semiconductor laser array device of the present disclosure can be applied to, for example, a semiconductor laser array device that emits light of blue-violet to infrared light for industrial processing. Further, it is also applicable to a semiconductor laser array device or the like that emits light in the visible range from blue-violet to red for a projector.

10, 20, 30, 1010 Semiconductor laser array device 100 Laminated body 101 Substrate 102 N-side clad layer 103 Active layer 104 p-side clad layer 105 p-side contact layer 106 Insulating layer 107 p-electrode 108 Pad electrode 109 n-electrode 121 First laser Part 122 Second laser part 123 Third laser part 125 Ridge part 126 Support part 127 Separation groove 141, 142, 241, 242, 341, 342 Groove part 241a, 242a, 341a, 342a First groove part 241b, 242b, 341b, 342b No. 2 groove part 1001 broad area laser 1002 epitaxial laminated body 1003 groove 1004 ridge 1005 terminal layer 1009 passivation part 1021 beam generating active layer 1022 upper surface 1023 lower surface A1, A2, d1, d2 width Dc center-to-center distance

Claims (6)

Board,
A laminate disposed above the substrate,
The stacked body includes a first semiconductor layer of a first conductivity type disposed above the substrate, an active layer disposed above the first semiconductor layer, and an active layer disposed above the active layer. A second semiconductor layer of a second conductivity type different from one conductivity type,
The laminated body is arranged along the active layer, and each has at least three light emitting portions that emit laser light,
Of the at least three light emitting portions, a groove portion that divides the stacked body is formed between two adjacent light emitting portions,
The groove portion extends from the upper surface of the laminated body to the lower surface, and the ratio of the volume of the groove portion to the sum of the volume of the laminated body and the volume of the groove portion between two adjacent groove portions. Is 20% or more, and the distance between the centers of the two adjacent light emitting portions is 200 μm or more. The substrate is gallium nitride,
The semiconductor laser array device according to claim 1, wherein the stacked body includes a gallium nitride-based material. The semiconductor laser array device according to claim 1, wherein the at least three or more light emitting units include four or more light emitting units. The groove is
A first groove portion,
The semiconductor laser array device according to claim 1, further comprising a second groove portion having a width narrower than the first groove portion and deeper than the first groove portion. The semiconductor laser array device according to claim 4, wherein the first groove portion has a depth to a main surface of the substrate or an inside of the substrate. The semiconductor laser array device according to claim 4, wherein the first groove portion has a depth to the inside of the first semiconductor layer.

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