Semiconductor laser device

Abstract

To provide a semiconductor laser device in which reliability is improved.SOLUTION: A semiconductor laser device 200A comprises: a submount 210; and an end surface light emission type semiconductor laser chip 100A which is junction-down mounted on the submount 210. m (m≥1) laser resonators 102 are formed on a lamination growth layer 120 of the semiconductor laser chip 100A. When the emission direction of a beam is the z axis, the thickness direction of a semiconductor substrate 110 is the y axis and the direction orthogonal to the z axis and y axis is the x axis, the m laser resonators 102 exist on the opposite side to the center xn of a second surface S2 of the semiconductor substrate 110 when viewed from the center xp of a first surface S1 of the semiconductor substrate 110 in the x axis direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a semiconductor laser device.

Background Art

[0002] As a high-power edge-emitting laser, a semiconductor laser having a ridge stripe type laser resonator is widely used.

[0003] Patent Document 1 and Patent Document 2 disclose a technique for junction-down mounting a semiconductor laser chip on a submount. Patent Document 1 discloses a technique for offsetting and arranging a light-emitting portion so as to approach directly below the load of die bonding in order to achieve good bonding between a semiconductor laser chip and a submount in a semiconductor laser device using a narrow-angle substrate. Patent Document 2 discloses a technique for arranging a light-emitting portion at the center of a semiconductor laser chip.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a result of studying the semiconductor laser devices described in Patent Document 1 and Patent Document 2, the present inventor has come to recognize the following problems. In Patent Document 1 and Patent Document 2, since the load of die bonding during junction-down mounting is applied to the light-emitting portion, that is, the laser resonator, there is a risk of reduced reliability. Note that this problem should not be grasped as a general recognition of those skilled in the art, but is uniquely recognized by the present inventors.

[0006] Some aspects of this disclosure were made in such circumstances, and one exemplary objective is to provide a semiconductor laser device with improved reliability. [Means for solving the problem]

[0007] Aspects of this disclosure relate to a semiconductor laser device. The semiconductor laser device comprises a submount and an end-emitting semiconductor laser chip junction-down mounted on the submount. The semiconductor laser chip includes a semiconductor substrate, a laminated growth layer formed on the first surface of the semiconductor substrate including a first conductivity type cladding layer, an emission layer, and a second conductivity type cladding layer, on which m (m≧1) laser resonators are formed, m P electrodes connected to the m laser resonators, and an N electrode formed on the second surface of the semiconductor substrate. When the beam emission direction is taken as the z-axis, the thickness direction of the semiconductor substrate as the y-axis, and the direction perpendicular to the z-axis and y-axis as the x-axis, the m laser resonators are located in the region of the semiconductor substrate excluding the area directly beneath the second surface, with respect to the x-axis. More preferably, they are located on the opposite side of the center of the second surface of the semiconductor substrate, as viewed from the center of the first surface of the semiconductor substrate.

[0008] Furthermore, any combination of the above components, or any substitution of components or expressions between methods, apparatus, systems, etc., are also valid as embodiments of the present invention or this disclosure. Moreover, the description in this section (means for solving the problem) does not describe all the indispensable features of the present invention, and therefore, subcombinations of these described features may also constitute the present invention. [Effects of the Invention]

[0009] According to certain aspects of this disclosure, the reliability of semiconductor laser devices can be improved. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a semiconductor laser device according to Example 1. [Figure 2] This is a cross-sectional view of a semiconductor laser device according to Modification 1. [Figure 3] This is a cross-sectional view of a semiconductor laser device according to modified example 2. [Figure 4] This diagram illustrates the position xc of the laser resonator. [Figure 5] Figures 5(a) to 5(c) are cross-sectional views of a semiconductor laser chip according to Modification Example 3. [Figure 6] This is a cross-sectional view of a semiconductor laser device according to modified example 4. [Figure 7] This is a cross-sectional view of a semiconductor laser device according to modified example 5. [Figure 8] This is a cross-sectional view of a semiconductor laser device according to modified example 6. [Figure 9] This is a cross-sectional view of the semiconductor laser device shown in Figure 1, relating to Modification 7. [Figure 10] This is a cross-sectional view of a semiconductor laser device according to Example 2. [Figure 11] This is a cross-sectional view of a semiconductor laser device according to modified example 8. [Figure 12] This is a cross-sectional view of the semiconductor laser device according to Example 3. [Figure 13] This is a cross-sectional view of a semiconductor laser device according to Example 4. [Modes for carrying out the invention]

[0011] (Summary of the embodiment) This section outlines some exemplary embodiments of the present disclosure. This outline serves as a prelude to the detailed description that follows, or as a means of understanding the embodiments. This outline provides a simplified explanation of some concepts of one or more embodiments and does not limit the scope of the invention or disclosure. Furthermore, this outline is not a comprehensive overview of all possible embodiments and does not limit the essential components of the embodiments. For convenience, “one embodiment” may be used to refer to one embodiment (example or variation) or more embodiments (example or variation) disclosed herein.

[0012] A semiconductor laser device according to an embodiment includes a submount and an end-face-emitting semiconductor laser chip junction-down mounted on the submount. The semiconductor laser chip includes a semiconductor substrate, a first conductivity type clad layer, a light-emitting layer, and a second conductivity type clad layer formed on a first surface of the semiconductor substrate, and a stacked growth layer including m (m≥1) laser resonators formed therein, m P electrodes connected to the m laser resonators, and an N electrode formed on a second surface of the semiconductor substrate. When taking the beam emission direction as the z-axis, the thickness direction of the semiconductor substrate as the y-axis, and the direction orthogonal to the z-axis and the y-axis as the x-axis, in the x-axis direction, the m laser resonators are present in a region excluding directly below the center of the second surface of the semiconductor substrate. More preferably, the m laser resonators are present on the side opposite to the center of the second surface of the semiconductor substrate when viewed from the center of the first surface of the semiconductor substrate.

[0013] When bonding (die-bonding) the semiconductor laser chip to the submount, a load is applied by a collet or the like to the back surface of the semiconductor laser chip, that is, the center of the second surface of the semiconductor substrate in junction-down mounting. In the above configuration, the m laser resonators are arranged offset in a direction away from the load position corresponding to the center of the second surface from the center of the first surface of the semiconductor substrate. Thereby, it is possible to prevent a large load from being directly applied to the laser resonator, and the reliability can be improved.

[0014] The position of the laser resonator in the x-direction shall refer to the center position of a current constriction structure such as a ridge structure. When m≥2, the position of the m laser resonators shall refer to the center of the positions of the laser resonators at both ends.

[0015] In one embodiment, the semiconductor substrate may be an inclined substrate having a first petalized surface with an acute angle with the first surface and a second petalized surface with an obtuse angle with the first surface. Note that the petalized surface is the cutting surface when singulating the semiconductor chip from a wafer or the like. In the x-axis direction, the position of the m laser resonators may be on the first petalized surface side rather than the center of the first surface.

[0016] In one embodiment, one of the m laser resonators, the position closest to the first pelletizing surface, may be further toward the first pelletizing surface than the end of the N electrode on the first pelletizing surface side.

[0017] In one embodiment, the side surface of the semiconductor laser chip may be substantially perpendicular to the submount in a first portion close to the submount, and inclined in a second portion farther from the submount. This structure will be described in detail later in Figure 5, etc. This structure appears by forming a pelletizing groove at a position corresponding to the pelletizing line of the semiconductor laser chip in the wafer state before pelletizing. By performing pelletizing after forming the pelletizing groove, even if the actual pelletizing line is misaligned, the pellet will break along the pelletizing groove, thus preventing the laser resonator from being affected when it is close to the side surface of the semiconductor laser chip.

[0018] In one embodiment, the side surface of the semiconductor laser chip may be covered with an insulating layer in the first portion. When the laser resonator is close to the side surface of the semiconductor laser chip, the PN junction can be protected by the insulating layer, thereby preventing short circuits caused by solder or foreign matter.

[0019] In one embodiment, the insulating layer on the side of the semiconductor laser chip may be covered with a metal layer. This allows the heat from the laser resonator to be dissipated using the metal layer on the side of the semiconductor laser chip.

[0020] In one embodiment, the semiconductor laser chip may further have a wide electrode adjacent to m P electrodes, forming a region that includes the center of the second surface of the semiconductor substrate. This results in a strong load being applied to the wide electrode, thereby enabling a robust bond between the semiconductor laser chip and the submount.

[0021] In one embodiment, m≧2, and the width of the P electrode may differ for each laser resonator. By controlling the width of the P electrode, variations in heat dissipation between multiple laser resonators can be reduced, and variations in stress occurring between multiple laser resonators can also be reduced.

[0022] A semiconductor laser apparatus according to one embodiment comprises a submount and an end-face emitting semiconductor laser chip mounted with junction down on the submount. The semiconductor laser chip includes a semiconductor substrate, a laminated growth layer formed on the first surface of the semiconductor substrate which includes a first conductivity type cladding layer, an emitting layer, and a second conductivity type cladding layer, and on which m (m≧1) laser resonators are formed, m P electrodes connected to the m laser resonators, and an N electrode formed on the second surface of the semiconductor substrate. When the beam emission direction is taken as the z axis, the thickness direction of the semiconductor substrate as the y axis, and the direction perpendicular to the z axis and y axis as the x axis, with respect to the x axis, the m laser resonators are located at positions that move away from the center of the first surface of the semiconductor substrate as a starting point, when viewed from the center of the N electrode.

[0023] In die bonding, the collet's adsorption position may be near the center of the N electrode on the second surface of the semiconductor substrate. In the above configuration, the m laser resonators are offset from the center of the first surface of the semiconductor substrate, away from the load position located near the center of the N electrode. This prevents a large load from being directly applied to the laser resonators, thereby improving reliability.

[0024] A semiconductor laser apparatus according to one embodiment comprises a submount and an end-face emitting semiconductor laser chip mounted with junction down on the submount. The semiconductor laser chip includes a semiconductor substrate, a laminated growth layer formed on the first surface of the semiconductor substrate which includes a first conductivity type cladding layer, an emitting layer, and a second conductivity type cladding layer, and on which m (m≧1) laser resonators are formed, m P electrodes connected to the m laser resonators, and an N electrode formed on the second surface of the semiconductor substrate. When the beam emission direction is taken as the z axis, the thickness direction of the semiconductor substrate as the y axis, and the direction perpendicular to the z axis and y axis as the x axis, with respect to the x axis, the m laser resonators are located at positions that move away from the center of the first surface of the semiconductor substrate as a starting point, when viewed from the center of the bonding wire connected to the N electrode.

[0025] In die bonding, the suction position of the collet and the center position of the bonding wire often coincide. In such cases, the load position during die bonding is located near the center of the bonding wire. In the above configuration, the m laser resonators are positioned offset from the center of the first surface of the semiconductor substrate in a direction away from the load position located near the center of the bonding wire. This prevents a large load from being directly applied to the laser resonators, thereby improving reliability.

[0026] (Embodiment) The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted where appropriate. Furthermore, the embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure.

[0027] The dimensions (thickness, length, width, etc.) of each component shown in the drawing may be enlarged or reduced as appropriate for ease of understanding. Furthermore, the dimensions of multiple components do not necessarily represent their relative sizes; even if component A is depicted as thicker than component B in the drawing, component A may actually be thinner than component B.

[0028] (Example 1) Figure 1 is a cross-sectional view of a semiconductor laser device 200A according to Embodiment 1. The semiconductor laser device 200A comprises an end-face emitting semiconductor laser chip 100A and a submount 210. Figure 1 shows the view from the emitting end face, and the beam is assumed to be emitted in the direction perpendicular to the plane of the paper. For the sake of explanation, coordinate axes are defined with the beam emission direction (depth direction of the paper) as the z axis, the thickness direction of the semiconductor substrate 110 (up and down direction of the paper) as the y axis, and the direction perpendicular to the z and y axes (left and right direction of the paper) as the x axis.

[0029] The semiconductor laser chip 100A is mounted in a junction-down configuration relative to the submount 210.

[0030] The semiconductor laser chip 100A has a laminated structure including a semiconductor substrate 110, a laminated growth layer 120, a P electrode 150, and an N electrode 152. The semiconductor substrate 110 is an N-type GaAs substrate in the case of a red laser, and may be an N-type GaN substrate in the case of a blue or green laser. The semiconductor substrate 110 has a first surface S1, a second surface S2, a first pelletizing surface Sp1, and a second pelletizing surface Sp2. The laminated growth layer 120 is formed on the first surface S1 side of the semiconductor substrate 110. The laminated growth layer 120 includes an N-type cladding layer 122, an emissive layer 130, a P-type cladding layer 124, and a P-type contact layer 126. The emissive layer 130 may include an N-type guide layer, an active layer (quantum well layer), and a P-type guide layer. An insulating layer 140 is formed on top of the laminated growth layer 120.

[0031] A waveguide structure for confining light is formed in the laminated growth layer 120, and the cleavage surfaces at both ends of this waveguide structure act as mirrors, forming a laser resonator 102. The exit end face of the laser resonator 102 becomes the emitter 104, and a beam is emitted from the emitter 104 in the z direction (towards the viewer). A reflective film with adjusted reflectivity may also be formed on the cleavage surface.

[0032] A semiconductor laser chip 100A has m (m≧1) laser resonators 102 formed on it. In this embodiment, m=1. As described in Example 3, when m≧2, the m laser resonators 102 are arranged adjacent to each other in the x-axis direction.

[0033] The waveguide structure can be, for example, a ridge structure. The ridge structure is formed by partially removing the P-type cladding layer 124. The ridge structure is also simply called a ridge or ridge stripe structure. A bank 106 is formed in the region adjacent to the laser resonator 102. The waveguide structure can also be an embedded ridge waveguide.

[0034] Alternatively, the waveguide structure may be a CSP (Channeled Substrate Planar) structure in which grooves are formed in the semiconductor substrate 110 along the waveguide, and the thickness of the N-type cladding layer 122 in the groove portion is relatively thicker.

[0035] Ridge structures and CPS structures are waveguide structures that utilize refractive index distributions, but this disclosure is not limited to these, and gain waveguide structures that utilize gain distributions may also be used. These structures can be understood as both optical confinement structures and current constriction structures.

[0036] An N electrode 152 is formed on the second surface S2 of the semiconductor substrate 110. One end of a bonding wire 220 is connected to the N electrode 152. The other end of the bonding wire 220 is connected to a wiring pattern on the submount 210.

[0037] P electrodes 150 are formed on the laminated growth layer 120 (on the lower side of the paper in Figure 1) at positions corresponding to each of the m laser resonators 102. Specifically, the insulating layer 140 has openings formed in the portions corresponding to the laser resonators 102, and P electrodes 150 that come into contact with the P-type contact layer 126 are formed therein. The P electrodes 150 are used to drive the laser resonators 102 and are therefore referred to as driving electrodes.

[0038] Furthermore, in the region corresponding to bank 106, a wide electrode (also called a bank electrode) 154 is formed adjacent to the P electrode 150. This wide electrode 154 is primarily intended for bonding with the submount 210, and is therefore also called a bonding electrode. In the embodiment shown in Figure 1, the P electrode 150 and the wide electrode 154 are electrically insulated. The N electrode 152 is referred to as the upper electrode. The P electrode 150 and the wide electrode 154 are collectively referred to as the lower electrode.

[0039] The semiconductor laser chip 100A is mounted in a junction-down configuration on a submount 210. The submount 210 can be made of a substrate with excellent heat dissipation properties, such as a ceramic substrate like aluminum nitride (AlN). In junction-down mounting, the laminated growth layer 120 of the semiconductor laser chip 100A is mounted facing the submount 210. Specifically, the P electrode 150 is electrically connected and mechanically joined to the wiring pattern 212 on the submount 210 by solder 214. The wide electrode 154 is also mechanically joined to the wiring pattern 216 by solder 218.

[0040] The junction-down mounting has the advantage of high cooling efficiency because the heat-generating laser resonator 102 is closer to the submount 210.

[0041] Regarding the x-axis direction, the position xc of the laser resonator 102 is described below. When m=1, position xc is the center position of the emitter 104, in other words, the center of the current constriction structure (ridge structure).

[0042] xp is the center of the first surface S1 of the semiconductor substrate 110 and is referred to as the reference position. xn is the center of the second surface S2 of the semiconductor substrate 110. When bonding the semiconductor laser chip 100A to the submount 210, the center position xn of the second surface S2 is attracted with a collet or the like, and a load is applied by pressing it against the solder-coated submount 210. In other words, the center position xn of the second surface S2 can be considered the load position during die bonding. Note that the actual load position may be offset from the center position xn.

[0043] In this embodiment, the laser resonator 102 is located on the opposite side of the load position xn, which is the center position of the second surface S2, when viewed from the reference position xp. In other words, the laser resonator 102 is located on the opposite side of the center of the first surface of the semiconductor substrate, when viewed from the center of the second surface of the semiconductor substrate. In other words, the laser resonator 102 is offset to a position xc that is away from the load position xn. This reduces the load on the laser resonator 102 during die bonding, thereby minimizing mechanical and optical effects.

[0044] In Figure 1, the semiconductor substrate 110 has tilted pelletizing surfaces Sp1 and Sp2. This is called a tilted substrate or inclined substrate. The first pelletizing surface Sp1 of the semiconductor substrate 110 has an acute angle (<90°) with the first surface S1, and the second pelletizing surface Sp2 of the semiconductor substrate 110 has an obtuse angle (>90°) with the first surface S1. The position xc of the laser resonator 102 is located closer to the first pelletizing surface Sp1 than the reference position xp.

[0045] The above describes the configuration of the semiconductor laser device 200A.

[0046] The load during die bonding is greatest at position xn. If the laser resonator 102 were placed at the reference position xp, which is the center of the first surface S1 of the semiconductor substrate 110, a large load would be applied to the laser resonator 102. This load could have an undesirable mechanical effect on the laser resonator 102 and reduce its reliability. According to the structure in Figure 1, the laser resonator 102 is positioned far from the load position xn, thus preventing a large load from being directly applied to the laser resonator 102 during die bonding and improving reliability.

[0047] The structure shown in Figure 1 can reduce the residual stress in the laser resonator 102. Residual stress also has an optical effect on the laser resonator 102. Specifically, residual stress causes changes in the refractive index of the waveguide, leading to unintended wavelength shifts and deviations in the waveguide direction. According to the structure shown in Figure 1, residual stress can be reduced, thereby stabilizing the optical performance.

[0048] Furthermore, since the wide electrode 154 is located at the load position xn, the bonding strength of the solder 218 can be increased.

[0049] Next, we will explain a modified version of the semiconductor laser device 200A.

[0050] (Variation 1) Figure 2 is a cross-sectional view of a semiconductor laser device 200Aa according to Modification 1. In the semiconductor laser device 200Aa, the P electrode 150 and the wide electrode 154 are electrically continuous. Also, the wiring patterns 212 and 216 are electrically continuous.

[0051] (Modification 2) Figure 3 is a cross-sectional view of the semiconductor laser apparatus 200Ab according to Modification 2. In this modification, the position xc of the laser resonator 102 is offset to a position even closer to the first pelletizing surface Sp1 than in the semiconductor laser apparatus 200A in Figure 1.

[0052] In FIG. 3, xd indicates the position of the end on the side of the first peretized surface Sp1 of the N electrode 152. In this modification, the position xc of the laser resonator 102 is closer to the first peretized surface Sp1 than the position xd.

[0053] FIG. 4 is a diagram for explaining the position xc of the laser resonator 102. The end of the semiconductor laser chip 100A is taken as the origin of the x coordinate. xd represents the position of the end of the electrode of the N electrode 152, and xe represents the position of the end of the second surface of the semiconductor substrate 110. xc, xe, and xd each represent the distance from the end of the semiconductor laser chip 100A.

[0054] In this case, xc ≦ xd It is preferable to satisfy. For example, when the inclination angle θ of the semiconductor substrate 110 is 10° and the total thickness t of the semiconductor substrate 110 and the stacked growth layer 120 is 100 μm, xe = 100 μm × tan 10° ≈ 18 μm. If the distance from the tip xe of the chip to the end of the N electrode 152 is 20 μm, then xd = 38 μm. Therefore, it may be designed to satisfy xc ≦ 38 μm.

[0055] In order to further reduce the influence of stress, xc ≦ xe It is preferable to set it as. When t = 100 μm and θ = 10°, it is only necessary to satisfy xc ≦ 18 μm.

[0056] The position xc and the thickness t may satisfy the relationship of xc < t / 3. When t = 100 μm, xc ≦ 33 μm.

[0057] The lower limit of the position xc is restricted by the beam diameter and the thickness of the P electrode 150. Specifically, if xc is made larger than 1 μm, stable performance and a yield that can withstand mass production are expected. Furthermore, considering the manufacturing stability, it is more preferable to set xc ≧ 4 μm.

[0058] In summary, the distance xc between the laser resonator 102 and the edge of the semiconductor laser chip 100A is preferably 38 μm or less, and more preferably 18 μm or less, in the above embodiment. Furthermore, the distance xc is preferably 1 μm or more, and more preferably 4 μm or more.

[0059] (Variation 3) The semiconductor laser chip 100A is formed by cutting it from a single wafer into individual pieces through pelletizing and cleavage. As in Modification 2, if the position xc of the laser resonator 102 is brought closer to the first pelletizing surface Sp1, the optical or mechanical properties of the laser resonator 102 may be affected if the position of the pelletizing line (pelletizing surface) shifts in the x-axis direction. Therefore, it is necessary to improve the precision of the pelletizing position.

[0060] Figures 5(a) to 5(c) are cross-sectional views of the semiconductor laser chip 100Ac according to Modification 3. Figure 5(a) shows the semiconductor laser chip 100Ac before pelletizing, and Figure 5(c) shows the semiconductor laser chip 100Ac after pelletizing.

[0061] As shown in Figure 5(a), before pelletizing, pelletizing grooves 160 are formed between adjacent semiconductor laser chips 100Ac during the wafer process. For example, after forming the P-type contact layer 126 on the semiconductor substrate 110, the pelletizing grooves 160 are formed by etching. Subsequently, insulating layers and electrodes are formed.

[0062] The pelletizing groove 160 is perpendicular to the semiconductor substrate 110, and its depth is greater than that of the light-emitting layer 130, reaching at least to the N-type cladding layer 122. The depth of the pelletizing groove 16 may reach the semiconductor substrate 110.

[0063] In the pelletizing process, the semiconductor laser chip 100Ac is cut out by splitting the wafer along the pelletizing line 162 that passes through the pelletizing groove 160. The pelletizing line 162 is usually a line that aligns with the crystal orientation of the semiconductor substrate 110.

[0064] Refer to Figure 5(b). Focus on the first pelletizing surface Sp1 side of the individualized semiconductor laser chip 100Ac. When pelletizing is performed after forming the pelletizing grooves, the side surface of the stacked growth layer 120 retains the traces of the pelletizing grooves 160, and therefore faces substantially perpendicular to the surface of the semiconductor substrate 110. On the other hand, the pelletizing surface Sp1 of the semiconductor substrate 110 faces an angle corresponding to the crystal orientation of the semiconductor substrate 110. As a result, the side surface of the semiconductor laser chip 100Ac is not flat, but has an angle φ.

[0065] Let's focus on the second pelletizing surface, Sp2. On the side of the stacked growth layer 120, most of the traces of the pelletizing groove 160 remain, resulting in a J-shaped cross-section. On the other hand, the side of the semiconductor substrate 110 (pelletizing surface Sp2) is oriented in a direction θ corresponding to the crystal orientation of the semiconductor substrate 110.

[0066] As shown in Figure 5(b), it is preferable to also form the insulating layer 140 on the surface of the pelletizing groove 160. This protects the PN junction on the sides Sp1 and Sp2 of the semiconductor laser chip 100Ac, thereby preventing short circuits caused by solder or foreign matter. If protection of the PN junction on the sides were to be achieved using a general manufacturing method without forming the pelletizing groove 160, it would be necessary to form a protective film in an additional process after pelletizing. In contrast, forming the insulating layer 140 on the surface of the pelletizing groove 160 has the advantage of eliminating the need for additional processes after pelletizing.

[0067] Figure 5(c) shows a modified example of the pelletizing groove 160. In this example, an insulating layer 140 is formed on the surface of the pelletizing groove 160, and an electrode 151 is formed on top of it. It is desirable that this electrode 151 is continuous with the P electrode 150.

[0068] According to the structure in Figure 5(c), the insulating layer 140 provides protection for the PN junction. Furthermore, the additional electrode 151 enhances heat dissipation. Since this electrode 151 is located close to the laser resonator 102, which is a heat source, a high heat dissipation effect can be expected. By making electrode 151 continuous with the P electrode 150, the heat dissipation effect can be further enhanced.

[0069] (Modification 4) Figure 6 is a cross-sectional view of the semiconductor laser apparatus 200Ad according to Modification 4. In this modification, instead of an angled substrate, a substrate with a rectangular cross-section and a vertical pelletizing surface is used as the semiconductor substrate 110. In this modification, the load position xn coincides with the reference position xp, which is the center of the first surface S1 of the semiconductor substrate 110. Even in this case, the condition that the laser resonator 102 is located at a position xc that moves away from the reference position xp as a starting point, relative to the load position xn, is satisfied.

[0070] (Variation 5) Figure 7 is a cross-sectional view of the semiconductor laser apparatus 200Ae according to Modification 5. In this modification, a semiconductor substrate 110 with a perpendicular pelletizing surface is used, similar to Figure 6. Figure 7 shows the die bonding process. The semiconductor laser chip 100Ae is pressed against the submount 210 by a collet 10. In this modification, the position xz of the collet 10 is offset from the center xn of the second surface S2, and position xz becomes the precise load position. In this case, the laser resonator 102 is located on the side closer to the pelletizing surface of the reference position xp, relative to the load position xz.

[0071] (Experimental variation 6) Figure 8 is a cross-sectional view of a semiconductor laser apparatus 200Af according to Modification 6. In this modification, a trapezoidal inclined substrate is used as the semiconductor substrate 110.

[0072] (Example 7) Figure 9 is a cross-sectional view of the semiconductor laser apparatus 200Ag according to Modification 7. In this modification, the ridge and adjacent bank are omitted. The wide electrode 154 is formed over a wide area including the load position xn. The thickness of the wide electrode 154 in Figure 9 is larger than that of the wide electrode 154 in Figure 1, etc., and in this modification, when bonded to the submount 210, it forms a height similar to that of the laser resonator 102.

[0073] (Other variations) A wide electrode 154 is formed adjacent to the P electrode 150 as a bonding electrode, but the width and structure of the bonding electrode are not particularly limited. For example, multiple narrow electrodes may be arranged in a row in the x-axis direction. In other words, the wide electrode 154 may be formed by dividing it into multiple parts in the x-axis direction.

[0074] (Example 2) Figure 10 is a cross-sectional view of the semiconductor laser device 200B according to Example 2. The semiconductor laser device 200B is a multi-beam laser and comprises a plurality of m (m≧2) laser resonators 102_1 to 102_m formed spaced apart in the x-axis direction. In Figure 7, m=2.

[0075] When m≧2, the position xc of the m laser resonators 102 is the center position between the emitter 104_1 of the laser resonator 102_1 at one end and the emitter 104_m of the laser resonator 102_m at the other end. In the example where m=2, if the positions of the laser resonators 102_1 and 102_2 at both ends are x1 and x2, then xc=(x1+x2) / 2.

[0076] Similar to Example 1, the center positions xc of the two laser resonators 102_1 and 102_2 are on the opposite side from the reference position xp when viewed from the load position xn. In other words, the center positions xc of the two laser resonators 102_1 and 102_2 are offset in the direction away from the load position xn (Figure (i)).

[0077] Furthermore, the positions x1 and x2 of the two laser resonators 102_1 and 102_2 can be seen as being offset in the same direction away from the load position xn, starting from the reference position xp (in the figure, (ii) and (iii)).

[0078] A modified example of Example 2 will be described below.

[0079] (Variation 8) Figure 11 is a cross-sectional view of a semiconductor laser apparatus 100Ba according to modified example 8. In this modified example, the widths Δx1 and Δx2 of the P electrodes 150_1 and 150_2 of the laser resonators 102_1 and 102_2 are different. By adjusting the electrode widths Δx1 and Δx2, the heat dissipation characteristics of the laser resonators 102_1 and 102_2 can be adjusted, and the operating temperature of the laser resonators 102_1 and 102_2 can be made uniform. In addition, by adjusting the electrode widths Δx1 and Δx2, the residual stress of the laser resonators 102_1 and 102_2 can be adjusted, and the optical characteristics of the laser resonators 102_1 and 102_2 can be made uniform.

[0080] (Other variations) In Figure 10, m=2 is shown as an example, but m may be 3 or greater. Furthermore, the modifications described in relation to Example 1 can be applied to Example 2.

[0081] (Example 3) Figure 12 is a cross-sectional view of the semiconductor laser device 200C according to Embodiment 3. The semiconductor laser device 200C is a multi-beam laser and comprises two semiconductor laser chips 100C and a submount 210. The two semiconductor laser chips 100C have the same configuration as the semiconductor laser chip 100A of Embodiment 1 and are symmetrical with respect to the x-axis direction.

[0082] As described in Example 1, by forming the laser resonator 102 close to the first pelletizing surface Sp1, the distance Wa between the two emitters 104 is designed according to the application of the semiconductor laser device 200C, but is, for example, 100 μm or less. When the gap g between the two semiconductor laser chips 100C is brought close to zero, the distance We between the position xc of the laser resonator 102 and the edge of the semiconductor laser chip 100C becomes Wa / 2 = 50 μm or less.

[0083] More specifically, as an example, the distance Wa between two emitters 104 can be set to Wa ≤ 50 μm. In this case, the distance We becomes ≤ 25 μm. If Wa ≤ 30 μm, then We becomes ≤ 15 μm.

[0084] In Example 3, the semiconductor substrate 110 of the semiconductor laser chip 100C is not limited to a tilted substrate, but may be the semiconductor substrate 110 shown in Figures 6 and 8.

[0085] In Example 3, the semiconductor laser chip 100C may have two or more laser resonators 102. In this case, the semiconductor laser chip 100B shown in Figure 10 may be configured and arranged so as to be symmetrical with respect to the x-axis direction.

[0086] (Example 4) Figure 13 is a cross-sectional view of the semiconductor laser apparatus 200D according to Example 4. In the explanation so far, it has been assumed that the load position during die bonding is located near the center of the second surface S2 of the semiconductor laser chip 100. In Example 4, the N electrode 152 is positioned offset to the right (or left) on the second surface S2 of the semiconductor laser chip 100D. In this case, the collet's adsorption position is near the center of the N electrode 152, and the load position xn is off-center from the second surface S2.

[0087] In Example 4, the N electrode 152 is designed with the center of the load position xn. The laser resonator 102 is located on the opposite side of the reference position xp from the load position xn, which is the center of the N electrode 152. In other words, the laser resonator 102 is offset to a position xc that is away from the load position xn, starting from the reference position xp. This reduces the load on the laser resonator 102 during die bonding, thereby minimizing mechanical and optical effects.

[0088] (Example 5) In Examples 1 to 3, it was assumed that the load position xn is located near the center of the second surface S2 of the semiconductor laser chip 100, and in Example 4, it was assumed that the load position xn is located near the center of the N electrode 152. In Example 5, as in Example 4, it can be explained using Figure 13, but the position of the laser resonator 102 is determined on the premise that the load position xn is located near the center of the bonding wire 220. That is, the laser resonator 102 is located on the side closer to the pelletized surface Sp1, opposite to the reference position xp, when viewed from the load position xn, which is the center of the bonding wire 220. In other words, the laser resonator 102 is positioned offset to a position xc that is away from the load position xn, starting from the reference position xp. This reduces the load on the laser resonator 102 during die bonding, thereby reducing mechanical and optical effects.

[0089] The embodiments merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are permitted in the embodiments, without departing from the spirit of the present invention as defined in the claims. [Explanation of Symbols]

[0090] 100 semiconductor laser chips 102 Laser resonator 110 Semiconductor substrates 120 Stacked Growth Layers 122 N-type cladding layer 124 P-type cladding layer 126 P-type contact layer 130 Emitting layer 140 Insulating layer 150P electrode 152 N electrode 154 Wide electrodes 160 Pelletized Grooves Sp1 1st Pelletized Surface Sp2 Second Pelletized Surface 200 Semiconductor laser devices 210 Submount 220 Bonding Wire

Claims

1. A semiconductor laser device, Submount and A junction-down mounted end-face emitting semiconductor laser chip is provided for the aforementioned submount, Equipped with, The aforementioned semiconductor laser chip is Semiconductor substrate and A laminated growth layer formed on the first surface of the semiconductor substrate, comprising a first conductivity type cladding layer, an emissive layer, and a second conductivity type cladding layer, wherein m (m≧1) laser resonators are formed in the laminated growth layer, m laser resonators and m P electrodes connected thereto, The N electrode formed on the second surface of the semiconductor substrate, It has, When the beam emission direction is taken as the z-axis, the thickness direction of the semiconductor substrate as the y-axis, and the direction perpendicular to the z-axis and y-axis as the x-axis, With respect to the x-axis, the m laser resonators are located in the region of the semiconductor substrate excluding the area directly below the center of the second surface. The semiconductor substrate is an angle-inclined substrate having a first pelletizing surface that forms an acute angle with the first surface and a second pelletizing surface that forms an obtuse angle with the first surface. A semiconductor laser apparatus characterized in that, with respect to the x-axis direction, the positions of the m laser resonators are on the side of the first pelletizing surface rather than the center of the first surface.

2. The semiconductor laser apparatus according to claim 1, characterized in that, among the m laser resonators, the position of the laser resonator closest to the first pelletizing surface is on the first pelletizing surface side of the end of the N electrode on the first pelletizing surface side.

3. The semiconductor laser apparatus according to claim 1, characterized in that the side surface of the semiconductor laser chip is perpendicular to the submount in a first portion close to the submount and inclined in a second portion farther from the submount.

4. The semiconductor laser apparatus according to claim 3, characterized in that the side surface of the semiconductor laser chip is covered with an insulating layer in the first portion.

5. The semiconductor laser apparatus according to claim 4, characterized in that the insulating layer on the side surface of the semiconductor laser chip is covered with a metal layer.

6. The aforementioned semiconductor laser chip is The semiconductor laser apparatus according to claim 1, further comprising a wide electrode adjacent to the m P electrodes and formed in a region including the center of the second surface.

7. The semiconductor laser apparatus according to claim 1, characterized in that m ≥ 2 and the width of the P electrode differs for each laser resonator.

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