METHOD FOR MANUFACTURING A SEMICONDUCTOR LASER COMPONENT

Abstract

A method for fabricating a semiconductor laser device of one embodiment comprises a first step of preparing a wafer, a second step of forming a device splitting groove by etching, a third step of forming a slit insertion groove at a position overlapping a slit line, a fourth step of obtaining a plurality of laser bars by splitting the wafer along the slit line, and a fifth step of splitting each of the plurality of laser bars along the device splitting line. In the second step, the device splitting groove is not formed on the slit line. In the third step, the slit insertion groove is formed only outside a device area, or the length of a portion of the slit insertion groove that is outside the device area is longer than the length of a portion of the slit insertion groove that is inside the device area.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for manufacturing a semiconductor laser device. REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Japanese Patent Application No. 2023-22487, filed on February 16, 2023, the entire contents of which are incorporated herein by reference. BACKGROUND

[0003] As a method for manufacturing a semiconductor laser device, a method for obtaining a plurality of semiconductor laser devices is known in which a semiconductor wafer is divided into a plurality of laser bars by primary cleaving (primary scribing and primary breaking), and then secondary cleaving (secondary scribing and secondary breaking) is performed on each laser bar (e.g., Japanese Unexamined Patent Publication No. 2003-17791). In the method disclosed in Japanese Unexamined Patent Publication No. 2003-17791, the plurality of laser bars are obtained by performing processing (primary scribing) in which a scribe is made in the semiconductor wafer by a diamond tool or the like in a direction perpendicular to an extension direction of a mesa light-emitting portion, and then dividing (primary breaking) the semiconductor wafer along a groove formed by the primary scribing.Subsequently, the plurality of semiconductor laser devices are obtained by performing processing (secondary scribing) in which a scribe is made along the extending direction of the mesa light-emitting portion on a front surface of each laser bar and then dividing (secondary breaking) each laser bar along a groove formed by the secondary scribing. PRESENTATION OF THE INVENTION

[0004] In the prior art method disclosed in Japanese Unexamined Patent Publication No. 2003-17791, it is difficult to efficiently manufacture a semiconductor laser device in a short time because many man-hours are required for secondary scribing, that is, inserting a plurality of scribings into each laser bar.

[0005] Therefore, an object of one aspect of the present disclosure is to provide a method of manufacturing a semiconductor laser device capable of reducing manufacturing man-hours without compromising the manufacturing quality of a semiconductor laser device.

[0006] The present disclosure includes a method for manufacturing a semiconductor laser device from [1] to

[13] , which will be described below.

[0007] [1] A method is provided for manufacturing a semiconductor laser device comprising a semiconductor substrate made of GaAs and a semiconductor stack body comprising an active layer and stacked on the semiconductor substrate.

[0008] The procedure includes a first step of preparing a wafer comprising a plurality of device sections, each of which will become the semiconductor laser device, and comprising a substrate layer comprising the semiconductor substrate of each of the plurality of device sections, and a semiconductor layer comprising the semiconductor stacked body of each of the plurality of device sections, wherein, in the wafer, the plurality of device sections are arranged in a matrix in a first direction parallel to an optical waveguide direction of the semiconductor stacked body and a second direction perpendicular to the first direction, viewed from a thickness direction of the wafer, a second step of forming a component division groove by etching on a first primary surface on a side of the wafer on which the semiconductor layer is positioned with respect to the substrate layer, or a second primary surface opposite the first primary surface along a component division line extending in the first direction to divide the plurality of component sections arranged in the second direction, a third step of forming a gap introduction groove to become a starting point of a gap on the first primary surface or the second primary surface at a position overlapping a gap line extending in the second direction to divide the plurality of component sections arranged in the first direction after the second step, a fourth step of obtaining a plurality of laser bars comprising a plurality of device sections arranged one-dimensionally in the second direction by cleaving the wafer along the cleavage line, and a fifth step of cleaving each of the plurality of laser bars along the device dividing line.

[0009] In the second step, the component division groove is not formed on the split line, and in the third step, the gap introduction groove is formed only outside a component region in which the plurality of component sections are arranged, or is formed such that a length of a portion of the gap introduction groove included outside the component region in the second direction is longer than a length of a portion of the gap introduction groove included inside the component region in the second direction.

[0010] In the manufacturing method of the above [1], the component division groove for the secondary cleavage (fifth step) is formed at the stage (second step) in the wafer state before the plurality of laser bars are obtained by the primary cleavage (fourth step). As a result, it is not necessary to perform scribe processing for each laser bar using a diamond tool, a laser, or the like as pre-processing for the secondary cleavage (fifth step) after the primary cleavage (fourth step). In addition, since the man-hours of the second step (i.e., the processing for forming the component division groove in the wafer state) are less than the man-hours required to perform the above-described scribe processing for each laser bar, it is possible to reduce the man-hours by the manufacturing process.In addition, since the component dividing groove is formed by etching, a deep damage layer generated when diamond scribing or the like is performed is not formed at the distal end portion (bottom portion) of the component dividing groove. As a result, it is possible to sufficiently ensure the strength of the wafer after the component dividing grooves are formed. As a result, even when back-side processing or the like of the wafer is performed after the second step, damage to the wafer is adequately prevented. In addition, the component dividing groove (etching groove) is not formed on the cleavage line, and the cleavage introduction groove is also formed mainly outside the component area.That is, the groove is not formed on the cleavage line in the device region, or, although the groove is formed, the groove is smaller than a portion formed outside the device region. As a result, it is possible to suppress the occurrence of a crack caused by the groove in the laser bar obtained by the primary cleavage (fourth step). In addition, the semiconductor substrate used is made of GaAs, which is relatively easy to break, and therefore, the primary cleavage (fourth step) can be performed easily and accurately along the cleavage line by only providing the cleavage introduction groove outside the device region. Accordingly, according to the above manufacturing method, it is possible to reduce the manufacturing man-hours without compromising the manufacturing quality of the semiconductor laser device.

[0011] [2] In the method for manufacturing a semiconductor laser device according to [1], in the third step, the gap introduction groove is formed only outside the device region.

[0012] According to [2] above, the gap introduction groove is not formed within the component region (specifically, a region between component portions adjacent in the first direction on the cleavage line). That is, neither the component division groove nor the gap introduction groove is formed on the cleavage line in the component region. As a result, it is possible to more effectively suppress the occurrence of the crack in the laser bar during the primary cleavage (fourth step) described above.

[0013] [3] In the method for manufacturing a semiconductor laser device according to [1] or [2], the device division groove is formed on the first primary surface, penetrates the semiconductor layer and reaches the substrate layer, and at least a portion of a first inner surface of the component dividing groove formed by the semiconductor layer in the second direction is inclined with respect to the thickness direction such that a width of the component dividing groove in the second direction decreases from the first primary surface side toward the second primary surface side.

[0014] According to the above [3], in a case where the portion of the first inner surface of the device dividing groove formed by the semiconductor layer functions as the side surface of the mesa light-emitting portion of the semiconductor laser device, it is possible to appropriately suppress the oscillation of the mesa light-emitting portion in a lateral direction (oscillation in the second direction). Furthermore, since the device dividing groove reaches the substrate layer, only the substrate layer can be divided in the secondary cleavage (fifth step). Accordingly, it is possible to reduce the risk of cracks occurring within the semiconductor layer at the time of secondary cleavage or the peeling of the semiconductor layer from the substrate layer.

[0015] [4] In the method for manufacturing a semiconductor laser device according to [3], the component dividing groove has a first portion positioned on an opening side of the component dividing groove and a second portion positioned on a bottom portion side of the component dividing groove with respect to the first portion, the first inner surface of the first portion is inclined in the thickness direction so that the width of the component dividing groove decreases in the second direction from the first primary surface side to the second primary surface side, an inclination angle of the first inner surface of the first portion with respect to the thickness direction is greater than an inclination angle of the first inner surface of the second portion with respect to the thickness direction, and the first section penetrates the semiconductor layer and reaches the substrate layer.

[0016] According to [4], the first inner surface of the first portion of the component dividing groove is inclined with respect to the thickness direction, and therefore, the laser bar can be easily divided along the component dividing line in the secondary cleavage (fifth step). On the other hand, in a case where the entire inner surface of the component dividing groove is inclined at a substantially constant inclination angle with respect to the thickness direction, it is difficult to accurately align the central position of the bottom portion of the component dividing groove on the component dividing line, and there is a concern that the component dividing cannot be performed accurately.Therefore, as described above, the second section is provided with a gentler slope with respect to the thickness direction than the first section on the bottom portion side of the component division groove, and thus the central position of the bottom portion of the component division groove can be accurately aligned with the component division line. Accordingly, according to the above configuration, component division (secondary splitting) can be easily performed by the first section, and the device division position can be precisely controlled by the second section.

[0017] [5] In the method for manufacturing a semiconductor laser device according to any one of [1] to [4], a bottom portion of the device division groove has a bottom surface extending in the second direction.

[0018] The component dividing groove with the bottom surface is formed as above [5], and therefore, the mechanical strength of the wafer can be increased compared to a case where the component dividing groove is formed in the V-shape. As a result, in a case where back surface processing or the like is performed on the wafer after the component dividing grooves are formed, it is possible to suppress damage to the wafer and improve yield. In addition, since the accuracy of etching deteriorates with increasing inclination, in a case where the component dividing groove is formed in a V-shape (ie,In a case where the entire inner surface of the component division groove is formed as an inclined surface, it is difficult to control the shape of the component division groove formed by etching, and as a result, there is a concern that the division direction (a direction along the division surface) becomes unstable at the time of component division. On the other hand, etching is performed so that the component division groove has the bottom surface, and thus the shape of the component division groove can be controlled more precisely than in a case where the component division groove is formed in a V-shape. As a result, the accuracy of component division can be improved.

[0019] [6] In the method for manufacturing a semiconductor laser device according to [5], a width of the bottom surface of the device division groove in the second direction is 20 µm or less.

[0020] According to the above [6], the width of the bottom surface is suppressed to a certain value or less (20 μm or less), and thus it is possible to easily divide the component along the component division groove while obtaining the effect of the case where the component division groove has the bottom surface as described above.

[0021] [7] In the method for manufacturing a semiconductor laser device according to any one of [1] to [6], the etching is a dry etching using a chlorine-based gas.

[0022] According to the above [7], since it is possible to perform vertical etching easily and accurately, it is possible to accurately control the shape of the component division groove.

[0023] [8] In the method for manufacturing a semiconductor laser device according to any one of [1] to [7], a second inner surface of the device dividing groove in the first direction is inclined with respect to the second direction to become narrow toward a substantially central portion of the device dividing groove in the second direction to an outer side in the first direction.

[0024] According to the above [8], it is possible to facilitate the component division along the substantially central portion of the component division groove in the second direction, compared with a case where the shape of the component division groove, viewed from the thickness direction, is a rectangular shape.

[0025] [9] In the method for manufacturing a semiconductor laser device according to [8], the second inner surface of the device division groove is formed in an R-shape as viewed in the thickness direction.

[0026] According to the above [9], the effect of the above [8] can be achieved, and the risk of occurrence of cracks in the second inner surface can be reduced by forming the second inner surface in the R-shape compared to a case where the second inner surface is formed in the rectangular shape.

[0027]

[10] In the method for manufacturing a semiconductor laser device according to any one of [1] to [9], an extending direction of the device division line is parallel to a [01-1] direction of the substrate layer.

[0028] According to

[10] above, the component division lines of the secondary cleavage (fifth step) are aligned with the [01-1] direction of the substrate layer, which is the crystal orientation in which breakage is difficult, and thus the mechanical strength of the wafer can be properly ensured after forming the component division grooves. Consequently, in a case where the above-described backside processing or the like is performed before the primary cleavage (fourth step), it is possible to properly suppress damage to the wafer.

[0029]

[11] In the method for manufacturing a semiconductor laser device according to any one of [1] to

[10] , the device division groove and the gap introduction groove are formed in the first primary surface.

[0030] According to the above

[11] , the quality of the cleavage along the component division groove or the cleavage introduction groove can be improved.

[0031]

[12] In the method for manufacturing a semiconductor laser device according to any one of [1] to

[11] , the second step comprises a step of forming a resistance film, wherein an opening portion overlapping a region including a central portion of a predetermined region in which the component dividing groove is formed is provided on a primary surface of the first primary surface or the second primary surface of the wafer on which the component dividing groove is formed before etching, and a thickness of the resistance film at a peripheral edge portion of the opening portion is formed to become thinner toward an end portion of the opening portion along the second direction.

[0032] According to

[12] above, the resistance film becomes thinner as etching progresses, and therefore, the width of the opening portion of the resistance film can be gradually increased in the second direction. As a result, the inner surface of the component division groove can be formed in the second direction to be inclined with respect to the thickness direction.

[0033]

[13] The method of manufacturing a semiconductor laser device according to any one of [1] to

[12] further comprises a step of forming an insulating film provided to cover a top surface of the semiconductor layer of the wafer and an inner surface of the device dividing groove, an opening portion in which a part of the top surface is exposed being provided in the insulating film, and forming an electrode covering at least a part of a portion of the insulating film that is in contact with the top surface via the opening portion and covers the top surface, after the second step and before the third step.

[0034] According to the above

[13] , in a case where the portion of the first inner surface of the device division groove formed by the semiconductor layer functions as the side surface of the mesa light-emitting portion of the semiconductor laser device obtained after device division, since the side surface of the mesa light-emitting portion can be adequately protected by the insulating film, it is possible to suppress the occurrence of dark line defects due to damage to the side surface of the mesa light-emitting portion. Moreover, the electrode is formed on top of the semiconductor layer through the insulating film, so the adhesion of the electrode can be further improved. As a result, the manufacturing quality of the semiconductor laser device can be improved.

[0035] According to one aspect of the present disclosure, it is possible to provide a method for manufacturing a semiconductor laser device capable of reducing the man-hours at the time of manufacturing without impairing the manufacturing quality of the semiconductor laser device. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view of a semiconductor laser device manufactured by a method of manufacturing a semiconductor laser device according to an embodiment; Fig. 2 is a cross-sectional view of the semiconductor laser device taken along the line II-II in Fig. 1; Fig. 3 is a cross-sectional view schematically showing a stacked structure of a semiconductor stack body of the semiconductor laser device in Fig. 1 represents; Fig. 4 is a plan view showing an example of a wafer manufactured in a first step; Fig. 5 is a partially enlarged plan view of the wafer including an example of a component dividing groove and a gap insertion groove formed in a second step and a third step; Fig. 6 is a partial cross-sectional view of the wafer showing a state after forming a resistance film in the second step; Fig. 7 is a partial cross-sectional view of the wafer, showing a state after the component division groove is formed in the second step; Fig. 8 is an SEM image of an example of the component division groove; Fig. 9 is a perspective view showing an example of the component division groove; Fig. 10A is a plan view of the component division groove in Fig. 9, and Fig. Figure 10B is a partial cross-sectional view of the wafer taken along line BB in Fig. 10A; Fig. 11 is a partial cross-sectional view of the wafer showing a state after performing the front side processing step; Fig. 12 is a partial cross-sectional view of the wafer, showing a state after performing the back-side processing step; Fig. 13 is a diagram schematically illustrating a component division step; Fig. 14 is a perspective view showing a modification example of the component division groove; Fig. 15 is a cross-sectional view of a semiconductor laser device according to a first modification example; and Fig. 16 is a cross-sectional view of a semiconductor laser device according to a second modification example. DETAILED DESCRIPTION

[0036] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that in the following description, identical or equivalent components are denoted by identical reference numerals, and redundant descriptions thereof will be omitted. The drawings may be partially simplified or exaggerated for clarity, and the dimensional relationships are not limited to those described in the drawings. [Semiconductor laser component]

[0037] An example of a semiconductor laser device (semiconductor laser device 1A) manufactured by a method for manufacturing a semiconductor laser device according to an embodiment will be described with reference to Fig. 1 to 3. As described in the Fig.1 to 3, the semiconductor laser device 1A includes a semiconductor substrate 2 and a semiconductor stacked body 3 stacked on the semiconductor substrate 2. In the present description, for convenience, an orthogonal XYZ coordinate system is defined in which a direction parallel to a thickness direction of the semiconductor substrate 2 is a Z-axis direction, a direction parallel to an optical waveguide direction (resonator length direction) of the semiconductor stacked body 3 is an X-axis direction (first direction), and a direction perpendicular to the optical waveguide direction (X-axis direction) viewed from the thickness direction (Z-axis direction) is a Y-axis direction (second direction). The Z-axis direction is also a direction in which the semiconductor substrate 2 and the semiconductor stacked body 3 face each other and is also a stacking direction of a plurality of layers included in the semiconductor stacked body 3.Note that the first direction may be a direction in which a pair of end faces intersecting the optical waveguide direction are opposite to each other. Furthermore, the first direction may be a direction perpendicular to an emission end face of a laser beam.

[0038] The semiconductor laser device 1A is, for example, an end-face emitting type laser diode that resonates a laser beam between the end faces of the semiconductor stack body 3 that are opposite to each other in the X-axis direction and emits a laser beam L from one end face along the X-axis direction. A length (resonator length) of the semiconductor laser device 1A in the X-axis direction is, for example, 0.5 mm to 2.0 mm, and is, for example, 1.0 mm in the present embodiment. The width of the semiconductor laser device 1A in the Y-axis direction is, for example, 300 μm to 1000 μm, and is, for example, 500 μm in the present embodiment.

[0039] The semiconductor substrate 2 is, for example, a GaAs substrate made of GaAs. The semiconductor substrate 2 has a front surface 2a on which the semiconductor stack body 3 is formed, a back surface 2b opposite the front surface 2a, and a side surface 2c (second side surface) that intersects the Y-axis direction as a whole and connects the front surface 2a and the back surface 2b. The front surface 2a of the semiconductor substrate 2 is a (100) plane. That is, the Z-axis direction orthogonal to the front surface 2a is a direction parallel to the

[100] direction of the semiconductor substrate 2.

[0040] The semiconductor stack body 3 is formed on the front surface 2a of the semiconductor substrate 2. The semiconductor stack body 3 has a top surface 3a opposite to a side facing the front surface 2a and a side surface 3b (first side surface) intersecting the Y-axis direction. The side surface 3b is continuously provided with the side surface 2c of the semiconductor substrate 2. That is, the side surface 3b is seamlessly connected to the side surface 2c at a connecting portion (boundary portion) between the side surface 3b and the side surface 2c. The side surface 3b of the semiconductor stack body 3 and a portion of the side surface 2c of the semiconductor substrate 2 continuous with the side surface 3b are formed as inclined surfaces inclined with respect to the Z-axis direction by etching in a step of forming a component division groove (second step) described later.Specifically, the side surface 3b is inclined outward in the Y-axis direction from the semiconductor stack body 3 side to the semiconductor substrate 2 side along the Z-axis direction. Thus, the semiconductor stack body 3 is formed in a mesa shape.

[0041] The side surface 2c of the semiconductor substrate 2 includes a first portion 2c1, a second portion 2c2, a third portion 2c3, and a fourth portion 2c4. The first portion 2c1 is a portion connected to the side surface 3b of the semiconductor stack body 3, continuous with the side surface 3b, and inclined with respect to the Z-axis direction. The second portion 2c2 is a portion connected to the first portion 2c1 opposite a side on which the side surface 3b is located with respect to the first portion 2c1. The third portion 2c3 is a portion connected to an end portion of the back surface 2b in the Y-axis direction and extending substantially parallel to the Z-axis direction.The fourth portion 2c4 is a portion extending slightly in the Y-axis direction to connect an end portion of the second portion 2c2 opposite a side connected to the first portion 2c1 and an end portion of the fourth portion 2c4 opposite a side connected to the back side 2b.

[0042] An inclination angle θ1 (see Fig.2) of the first portion 2c1 with respect to the Z-axis direction is larger than an inclination angle of the second portion 2c2 with respect to the Z-axis direction. For example, the second portion 2c2 extends substantially parallel to the Z-axis direction, and the inclination angle of the second portion 2c2 with respect to the Z-axis direction is substantially 0 degrees. On the other hand, the inclination angle θ1 is, for example, 5 degrees to 25 degrees. Note that, as described above, since the first portion 2c1 is continuous with the side surface 3b, an inclination angle of the side surface 3b with respect to the Z-axis direction substantially coincides with the inclination angle θ1 of the first portion 2c1.

[0043] An edge portion of the top surface 3a of the semiconductor stack body 3 in the Y-axis direction, the entire side surface 3b of the semiconductor stack body 3, and a portion of the side surface 2c of the semiconductor substrate 2 except for the third portion 2c3 are covered with an insulating film 4. The insulating film 4 can be made of, for example, a silicon nitride layer or a silicon oxide layer. An opening portion 4a for exposing a portion of the top surface 3a (in the present embodiment, a central portion of the top surface 3a in the Y-axis direction) is provided in a portion of the insulating film 4 covering the top surface 3a. The opening portion 4a has a constant width in the Y-axis direction and extends in the X-axis direction.

[0044] An electrode 5 on the front side of the semiconductor laser device 1A is formed to contact the top surface 3a via the opening portion 4a of the insulating film 4 and to cover at least a part of the portion of the insulating film 4 covering the top surface 3a. A contact area between the electrode 5 and the top surface 3a extends in the X-axis direction, and laser resonance occurs along the X-axis. An electrode 6 on the back side of the semiconductor laser device 1A is provided on the back side 2b of the semiconductor substrate 2. The electrode 5 can be made of, for example, Ti / Pt / Au. The electrode 6 can be made of, for example, AuGe / Ni / Au.

[0045] As in Fig.3, the semiconductor stack body 3 includes, for example, a lower first cladding layer 301, a lower active layer 302 (active layer), a lower second cladding layer 303, a lower tunnel barrier layer 304, a first intermediate cladding layer 305, an intermediate active layer 306 (active layer), a second intermediate cladding layer 307, a middle tunnel barrier layer 308, an upper first cladding layer 309, an upper active layer 310 (active layer), an upper second cladding layer 311, and a contact layer 312, which are laminated in this order on the front side 2a of the semiconductor substrate 2. The semiconductor stack body 3 can be formed by growing these layers on the front side 2a of the semiconductor substrate 2, e.g., using a metal organic chemical vapor deposition (MOCVD) method.

[0046] In the present embodiment, for example, the semiconductor stacked body 3 includes a plurality (here, three) active layers. The semiconductor laser device 1A can be considered as a series circuit of a first laser diode including the upper first cladding layer 309, the upper active layer 310, and the upper second cladding layer 311; a second laser diode including the first intermediate cladding layer 305, the intermediate active layer 306, and the second intermediate cladding layer 307; and a third laser diode including the lower first cladding layer 301, the lower active layer 302, and the lower second cladding layer 303. A current flows in a forward direction from the electrode 5 (an electrode on a P-type semiconductor side) to the electrode 6 (an electrode on an N-type semiconductor side); each of the first to third laser diodes emits light and emits the laser beam L in the X-axis direction.

[0047] Examples of a combination of a thickness of each layer constituting the semiconductor stack body 3, a suitable range of the thickness, and a conductivity type are shown in Table 1. [Table 1] Component Thickness (µm) Suitable thickness range (µm) Conductivity type Contact layer 312 0,2 0.05 or more and 2.0 or less P Upper second cladding layer 311 2, 0 1.5 or more and 3.0 or less P Upper active layer 310 0,02 0.01 or more and 0.1 or less Upper first mantle layer 309 2, 0 1.5 or more and 3.0 or less N Middle tunnel barrier layer 308 0,2 0.05 or more and 0.4 or less Second intermediate cladding layer 307 2, 0 1.5 or more and 3.0 or less P Intermediate active layer 306 0,02 0.01 or more and 0.1 or less First intermediate cladding layer 305 2, 0 1.5 or more and 3.0 or less N Lower tunnel barrier layer 304 0,2 0.05 or more and 0.4 or less Lower second cladding layer 303 2, 0 1.5 or more and 3.0 or less P Lower active layer 302 0,02 0.01 or more and 0.1 or less Lower first cladding layer 301 2, 0 1.5 or more and 3.0 or less N Semiconductor substrate 2 120 90 or more and 150 or less N

[0048] Examples of a combination of material and an impurity concentration of each layer constituting the semiconductor stack body 3 are shown in Table 2. The number of active layers stacked in the semiconductor stack body 3 is not limited to three and may be four or more. [Table 2] Component material Contaminant concentration (cm -3 ) Suitable range of impurity concentration (cm -3 ) Contact layer 312 GaAs 1×10 20 1 × 10 19 or more 2 × 10 20 or less upper second cladding layer 311 AlGaAs 1×10 18 1 × 10 17 or more 2 × 10 18 or less Upper active layer 310 InAlGaAs Not endowed - Upper first mantle layer 309 AlGaAs 1×10 18 1 × 10 17 or more 2 × 10 18 or less Middle tunnel barrier layer 308 GaAs 1×10 19 5 × 10 18 or more 1 × 10 20 or less Second intermediate cladding layer 307 AlGaAs 1×10 18 1 × 10 17 or more 2 × 10 18 or less Intermediate active layer 306 InAlGaAs Not endowed - First intermediate cladding layer 305 AlGaAs 1×10 18 1 × 10 17 or more 2 × 10 18 or less Lower tunnel barrier layer 304 GaAs 1×10 19 5 × 10 18 or more 1 × 10 20 or less Lower second cladding layer 303 AlGaAs 1×10 18 1 × 10 17 or more 2 × 10 18 or less Lower active layer 302 InAlGaAs Not endowed - Lower first cladding layer 301 AlGaAs 1×10 18 1 × 10 17 or more 2 × 10 18 or less Semiconductor substrate 2 GaAs 1×10 18 5 × 10 17 or more 2 × 10 18 or less [Method for manufacturing a semiconductor laser device]

[0049] An example of a method for manufacturing the semiconductor laser device 1A will be described with reference to Fig. 4 to 13 described. (First step: wafer preparation step)

[0050] First, as in the Fig. 4 and Fig. 5, a disk-shaped wafer 100 (semiconductor element) having a plurality of device sections C, which will become semiconductor laser devices 1A, is prepared. Fig. Figure 5 is an enlarged plan view of a square area A in Fig.4. The region A is, for example, a square region with a side of 30 mm. A central region of the region A in the Y-axis direction (i.e., a region excluding both side edge portions of the region A in the Y-axis direction) is formed as a device region A1 in which the plurality of device portions C are arranged. An end portion of the device region A1 in the Y-axis direction coincides with an outer end portion of the semiconductor laser device 1A in the Y-axis direction (strictly speaking, a portion that becomes the semiconductor laser device 1A after device division), which is positioned on an outermost side in the Y-axis direction. In other words, a side portion along the end portion of the device region A1 in the Y-axis direction (an upper side and a lower side of the device region A1 in Fig.5) coincides with a component division line L2 positioned on an outermost side in the Y-axis direction. Note that in Fig. 5 shows a plurality of component division grooves 20 and a plurality of gap insertion grooves 30 formed in a step of forming component division grooves (second step) and a step of forming gap insertion grooves (third step), which will be described later. Furthermore, in Fig. 5, a shape of the component division groove 20 viewed from the Z-axis direction is shown in a simple rectangular shape, but in the present embodiment, the component division groove 20 is actually formed in a boat shape as shown in Fig. 10A shown in plan view.

[0051] As in Fig.6, the wafer 100 includes a substrate layer 2L and a semiconductor layer 3L. The substrate layer 2L is a layer including the semiconductor substrate 2 of each of the plurality of device sections C (i.e., sections that will become individual semiconductor laser devices 1A after device division). In other words, the substrate layer 2L has a structure in a state where the semiconductor substrate 2 of each of the plurality of device sections C extends continuously along an XY plane without being separated. The semiconductor layer 3L is a layer including the semiconductor stacked body 3 of each of the plurality of device sections C. In other words, the semiconductor layer 3L has a structure in a state where the semiconductor stacked body 3 of each of the plurality of device sections C extends continuously along the XY plane without being separated.

[0052] The substrate layer 2L has a front side 2La and a back side 2Lb, which are portions that become the front side 2a and the back side 2b of the semiconductor substrate 2 of each of the individual semiconductor laser devices 1A after device division. The semiconductor layer 3L can be formed, for example, by growing the layers (layers corresponding to the layers 301 to 312 in Fig. 3), which form the semiconductor layer 3L, are formed on the front surface 2La of the substrate layer 2L using the MOCVD method described above. The semiconductor layer 3L has a top surface 3La, which is a portion of the top surface 3a of the semiconductor stack body 3 of each individual semiconductor laser device 1A after device division. In the present embodiment, the front surface 2La of the substrate layer 2L is, for example, the (100) plane. In addition, one direction (ie, a positive direction of the Y-axis in Fig.4) perpendicular to a flat machined orientation surface of the substrate layer 2L (a flat surface formed on a lower side in Fig. 4) a

[011] direction of the substrate layer 2L. A positive direction of the X-axis in Fig. 4 is a [01-1] direction of the substrate layer 2L.

[0053] The wafer 100 has a first primary surface 100a on a side where the semiconductor layer 3L is positioned relative to the substrate layer 2L, and a second primary surface 100b opposite the first primary surface 100a. In the present embodiment, the first primary surface 100a is formed by the top surface 3La of the semiconductor layer 3L. The second primary surface 100b is formed by the back surface 2Lb of the substrate layer 2L.

[0054] In the present embodiment, a plurality of component sections C are included within the component area A1. The plurality of component sections C are arranged in a matrix in the X-axis direction and the Y-axis direction. As shown in Fig.5, a plurality of cleavage lines L1 extending in the Y-axis direction are formed in the wafer 100 to divide the plurality of component sections C arranged in the X-axis direction (i.e., to divide two component sections C adjacent in the X-axis direction). Furthermore, a plurality of component dividing lines L2 extending in the X-axis direction are formed on the wafer 100 to divide the plurality of component sections C arranged in the Y-axis direction (i.e., to divide two component sections C adjacent in the Y-axis direction). The cleavage lines L1 are lines along which the wafer 100 is to be divided in a primary cleavage step (fourth step) described later. The component dividing lines L2 are lines along which a laser bar LB (see Fig. 13) is to be divided in a secondary cleavage step (fifth step) to be described later.

[0055] An extension direction (i.e., the X-axis direction) of each of the plurality of component division lines L2 is set to be parallel to the [O1-1] direction of the substrate layer 2L. According to the above configuration, the component division lines L2 of the secondary cleavage (fifth step) are aligned with the [O1-1] direction of the substrate layer 2L, which is a crystal orientation in which breakage is difficult, and therefore, the mechanical strength of the wafer 100 can be appropriately ensured after forming the component division grooves 20 in the component division groove forming step (second step) to be described later. Thereby, in a case where back-side processing (e.g., a back-side processing step to be described later) is performed before the primary cleavage (fourth step), it is possible to appropriately suppress damage to the wafer 100.That is, since the back processing or the like can be performed in a state where a certain mechanical strength is ensured, it is possible to reduce the risk of unexpected damage to the wafer 100 during the back processing or the like or when the wafer 100 is moved to perform the back processing or the like. (Second step: step of forming the component division groove)

[0056] Then, as in Fig.As shown in Figure 5, the component division grooves 20 are formed by etching on the first primary surface 100a of the wafer 100 along each of the plurality of component division lines L2. The etching is performed by dry etching with a chlorine-based gas. The component division grooves 20 can be formed, for example, by reactive ion etching (RIE) using an inductively coupled plasma (ICP). Dry etching using a chlorine-based gas enables simple and precise vertical etching. This makes it possible to precisely control the shape of the component division groove 20.

[0057] The component division grooves 20 are individually formed in regions between the plurality of component sections C that are adjacent in the X-axis direction and do not straddle the cleavage lines L1. That is, an etching groove is not formed on the cleavage line L1. In the present embodiment, for example, the distance between the cleavage lines L1 adjacent to each other in the X-axis direction is 1.0 mm (i.e., the resonator length of the semiconductor laser device 1A described above), and the length of the component division groove 20 in the X-axis direction is 0.8 mm. A center of the component division groove 20 in the X-axis direction substantially coincides with a center of a region in the X-axis direction (i.e., the component section C) between the cleavage lines L1 adjacent to each other in the X-axis direction.That is, in the present embodiment, a separation distance (distance in the X-axis direction) between an end portion of the component division groove 20 in the X-axis direction and the split line L1 closest to the end portion is 0.1 mm. Note that the length of the component division groove 20 in the X-axis direction can be selected, for example, from a range of 0.8 mm to 0.95 mm.

[0058] An example of the step of forming the component division groove and an example of the component division groove 20 formed by the step of forming the component division groove will be described with reference to FIG. Fig. 6 to 10B are described in detail. Fig. 6 and Fig. 7 shows a cross section of the wafer 100 at a position where the component dividing groove 20 is to be formed (a substantially central position of the component dividing groove 20 in the X-axis direction).

[0059] First, a configuration of the component division groove 20 will be described with reference to Fig. 7 to 10B. As described in Fig. 7, the component division groove 20 penetrates the semiconductor layer 3L and reaches the substrate layer 2L. As shown in the Fig. 7 and Fig.8, the component dividing groove 20 further includes a first portion 21 located on an opening side of the component dividing groove 20, and a second portion 22 located on a bottom portion side of the component dividing groove 20 with respect to the first portion 21. A bottom portion of the component dividing groove 20 has a bottom surface 23 extending substantially parallel to the Y-axis direction. In other words, the bottom portion of the component dividing groove 20 does not have a pointed shape like a V-shaped groove, and a substantially flat portion (bottom surface 23) having a constant width in the Y-axis direction is formed at the bottom portion of the component dividing groove 20.

[0060] A width of the bottom surface 23 in the Y-axis direction is preferably set to 20 μm or less, and more preferably to 10 μm or less, from the viewpoint of ensuring control accuracy in a crack development direction at the time of component division. Furthermore, from the viewpoint of ensuring mechanical strength of the wafer 100 after forming the component division grooves 20, the width of the bottom surface 23 in the Y-axis direction is preferably set to 5 μm or more. An opening width of the component division groove 20 in the Y-axis direction (i.e., a width of an upper end opening of the first portion 21 in the Y-axis direction) is preferably set to 10 μm or more. The depth of the component division groove 20 in the Z-axis direction (ie, the distance between the upper end of the first portion 21 and the bottom portion of the second portion 22) is preferably set to 20 µm or more.In the example of . Fig. 8, the width of the bottom surface 23 in the Y-axis direction (= a width of the second portion 22 in the Y-axis direction) is 7.25 μm, the opening width of the component division groove 20 in the Y-axis direction is 31.2 μm, and the depth of the component division groove 20 in the Z-axis direction is 40.1 μm. Moreover, in the present embodiment, a depth of the first portion 21 in the Z-axis direction (a length of the first portion 21 in the Z-axis direction) is greater than a depth of the second portion 22 in the Z-axis direction (a length of the second portion 22 in the Z-axis direction). The depth of the first portion 21 is increased, and thereby it is possible to efficiently increase the volume of the component division groove 20. As a result, it is possible to easily divide the device.

[0061] The component division groove 20 has a pair of inner surfaces 20a (first inner surfaces) in the Y-axis direction and a pair of inner surfaces 20b (second inner surfaces) in the X-axis direction. The pair of inner surfaces are surfaces provided at positions opposite to each other in the Y-axis direction, with a substantially central portion of the component division groove 20 interposed therebetween as viewed from the Z-axis direction. The two inner surfaces 20b are surfaces provided at positions opposite to each other in the X-axis direction, with a substantially central portion of the component division groove 20 interposed therebetween as viewed from the Z-axis direction.

[0062] As in Fig.As shown in FIG. 7, at least a portion of the inner surface 20a formed by the semiconductor layer 3L is inclined with respect to the Z-axis direction so that the width of the component division groove 20 decreases in the Y-axis direction from the first primary surface 100a side to the second primary surface 100b side. In the present embodiment, the inner surface 20a of the first portion 21 is inclined with respect to the Z-axis direction so that the width of the component division groove 20 decreases in the Y-axis direction from the first primary surface 100a side to the second primary surface 100b side. Moreover, an inclination angle θ1 of the inner surface 20a of the first portion 21 with respect to the Z-axis direction is larger than an inclination angle of the inner surface 20a of the second portion 22 with respect to the Z-axis direction.For example, the inner surface 20a of the second portion 22 extends substantially parallel to the Z-axis direction, and an inclination angle of the inner surface 20a of the second portion 22 with respect to the Z-axis direction is substantially 0 degrees. Note that the inner surface 20a of the first portion 21 is a portion corresponding to the side surface 3b and the first portion 2c1 of the side surface 2c of the semiconductor laser device 1A obtained after device division. The inner surface 20a of the second portion 22 is a portion corresponding to the second portion 2c2 of the side surface 2c of the semiconductor laser device 1A obtained after device division.

[0063] As in the Fig. 9, Fig. 10A and Fig.As shown in Fig. 10B, the inner surface 20b of the component dividing groove 20 is inclined with respect to the Y-axis direction so as to become narrower toward a substantially central portion of the component dividing groove 20 in the Y-axis direction toward an outer side in the X-axis direction. In the present embodiment, for example, the inner surface 20b of the component dividing groove 20 is formed in a boat shape inclined with respect to the Y-axis direction so as to become narrower toward a substantially central portion of the component dividing groove 20 in the Y-axis direction toward the outer side in the X-axis direction in both the first portion 21 and the second portion 22.

[0064] Next, an example of a method for forming the component division groove 20 in the above-described shape will be described. As shown in Fig.As shown in Figure 6, the step of forming the component division groove includes a step of forming a resistance film 40 on the first primary surface 100a (the primary surface on which the component division groove 20 is formed) of the wafer 100 before etching. An opening portion 40a is provided in the resistance film 40, which overlaps with a central portion of a region where the component division groove 20 is to be formed. The opening portion 40a defines a size of the second portion 22 of the component division groove 20, which will be described later, as viewed in the Z-axis direction. More specifically, the width of the second portion 22 of the component division groove 20 in the Y-axis direction obtained after the step of forming the component division groove is slightly larger than the width of the opening portion 40a in the Y-axis direction before the start of etching.Similarly, a width of the second portion 22 of the component dividing groove 20 in the X-axis direction obtained after the step of forming the component dividing groove is slightly larger than a width of the opening portion 40a in the X-axis direction before the start of etching. In the example of FIG. Fig. 8, the width of the opening portion 40a in the Y-axis direction before starting etching is set to 5 µm, and thereby the width of the bottom surface 23 in the Y-axis direction (= the width of the second portion 22 in the Y-axis direction) is set to 7.25 µm.

[0065] As in Fig.As shown in FIG. 7, a thickness of the resistance film 40 at a peripheral edge portion of the opening portion 40a is formed to decrease toward an end portion of the opening portion 40a in the Y-axis direction. According to the above configuration, the resistance film 40 becomes thinner as etching progresses, and thereby the width of the opening portion 40a of the resistance film 40 in the Y-axis direction can be gradually increased. As a result, it is possible to make the inner surface 20a of the component division groove 20 in the Y-axis direction inclined with respect to the Z-axis direction. That is, it is possible to easily form the inner surface 20a of the first portion 21 described above.Furthermore, etching proceeds in the vertical direction (Z-axis direction) until a portion of an edge portion of the opening portion 40a of the resistance film 40 is reduced, and the opening portion 40a begins to expand in the Y-axis direction after etching begins. As a result, it is possible to easily form the second portion 22 extending substantially perpendicular to the Z-axis direction as viewed in the X-axis direction.

[0066] In addition, as in the Fig. 9, Fig. 10A and Fig.10B, in the present embodiment, the inner surface 20b of the first portion 21 is inclined with respect to the Z-axis direction, so that the width of the component division groove 20 in the X-axis direction decreases from the first primary surface 100a side to the second primary surface 100b side. Moreover, an inclination angle of the inner surface 20b of the first portion 21 with respect to the Z-axis direction is larger than an inclination angle (about 0 degrees in the present embodiment) of the inner surface 20b of the second portion 22 with respect to the Z-axis direction. It is also possible to easily form such a shape by the method described above using the resistance film 40. That is, the thickness of the resistance film 40 at the peripheral edge portion of the opening portion 40a can be formed to decrease toward the end portion of the opening portion 40a in the X-axis direction.According to the above configuration, the resistance film 40 becomes thinner as etching progresses, and thereby the width of the opening portion 40a of the resistance film 40 in the X-axis direction can be gradually increased. As a result, it is possible to form the inner surface 20b of the component division groove 20 in the X-axis direction so as to be inclined with respect to the Z-axis direction. That is, it is possible to easily form the inner surface 20b of the above-described first portion 21. Moreover, the etching proceeds in the vertical direction (Z-axis direction) until the portion of the edge portion of the opening portion 40a of the resistance film 40 is reduced, and the opening portion 40a begins to expand in the X-axis direction after etching begins. As a result, it is possible to easily form the second portion 22 extending substantially perpendicular to the Z-axis direction as viewed in the Y-axis direction.

[0067] The semiconductor layer 3L of each device section C is formed in a mesa shape by being separated into the semiconductor layers 3L of the device sections C adjacent to each device section C by the device dividing groove 20 formed on both sides of each device section C in the Y-axis direction. That is, in the present embodiment, the step of forming the device dividing groove also serves as a mesa forming step to form a mesa section. (Front processing step)

[0068] Then, as in Fig.11, a front-side processing step (front-side process) is performed. First, the insulating film 4 is formed to cover the top surface 3La of the semiconductor layer 3L of the wafer 100 and the inner surfaces 20a and 20b of the component division grooves 20. The opening portion 4a, which exposes a part of the top surface 3La, is provided in the insulating film 4. The insulating film 4 is formed to extend in the X-axis direction along each of the plurality of component division lines L2 within the component region A1 (see Fig.5), for example. Subsequently, the electrode 5 is formed to be in contact with the upper surface 3La via the opening portion 4a and to cover at least a portion of the insulating film 4 covering the upper surface 3La. For example, the electrode 5 is formed within the device region A1 to extend in the X-axis direction along a central portion of each device section C between the mutually adjacent device division lines L2 and L2.

[0069] In the present embodiment, the inner surface 20a of the first portion 21 of the component dividing groove 20 has a shape that widens toward the opening side of the component dividing groove 20. Thus, in a case where the insulating film 4 is formed by the CVD method or the like, since gas easily enters the interior of the first portion 21, it is possible to appropriately form the insulating film 4 on the inner surface 20a of the first portion 21. Since the first portion 21 penetrates the semiconductor layer 3L and reaches the substrate layer 2L, it is possible to reliably form the insulating film 4 on the entire inner surface 20a of the semiconductor layer 3L including the active layer. On the other hand, on the back side of the first portion 21, gas hardly penetrates into the interior of the second portion 22, which is not inclined with respect to the Z-axis direction like the first portion 21.Thus, it is possible to set the thickness of the insulating film 4 formed on the second portion 22 and the bottom surface 23 smaller than the thickness of the insulating film 4 formed on the first portion 21. This makes it possible to reduce the possibility that the insulating film 4 formed on the bottom surface 23 adversely affects the component pitch. (Back processing step)

[0070] Then, as in Fig. 12, the backside processing step (backside process) is performed. First, the backside 2Lb of the substrate layer 2L of the wafer 100 is scraped off, thus performing thinning processing of the wafer 100 (substrate layer 2L). Subsequently, the electrode 6 is formed on the backside 2Lb of the thinned substrate layer 2L. The electrode 6 is formed, for example, on the entire backside 2Lb of the device region A1. (Third step: step of forming the gap introduction groove)

[0071] Then, as in Fig. 5, at a position overlapping each of the plurality of cleavage lines L1, the cleavage introduction groove 30 serving as a cleavage starting point is formed on the first primary surface 100a or the second primary surface 100b. The cleavage introduction groove 30 is formed outside the component region A1 in which the plurality of component sections C are arranged. That is, the cleavage introduction groove 30 is not formed between the plurality of component sections C adjacent to each other in the X-axis direction (that is, a region overlapping the cleavage line L1 within the component region A1).

[0072] The gap introduction groove 30 can be formed, for example, by diamond scribing with a diamond tool or the like. In the present embodiment, the plurality of gap introduction grooves 30 are formed on the first primary surface 100a where the plurality of component division grooves 20 are formed. That is, in the present embodiment, both the component division groove 20 and the gap introduction groove 30 are formed on the first primary surface 100a. According to the above configuration, the quality of the gap along the component division groove 20 or the gap introduction groove 30 can be improved.Since the electrode 6 is formed on the entire second primary surface 100b as described above, in a case where a scribed groove (component division groove or gap insertion groove) is provided by performing scribing on the second primary surface 100b from above the electrode 6, it is not possible to accurately form the scribed groove due to the presence of the electrode 6, and sufficient gap quality cannot be obtained. Furthermore, to avoid the above-described deterioration in gap quality, it is conceivable to pattern the electrode 6 so as to avoid a position where the scribed groove is formed, but in this case, the working time increases by the amount of patterning. On the other hand, the component division groove 20 and the gap insertion groove 30 are formed in the first primary surface 100a as described above, and thereby it is possible to avoid the above-described disadvantage. (Fourth step: primary cleavage step)

[0073] Subsequently, the wafer 100 is cut along an outer edge portion of the region A to obtain a square plate-shaped member including only the region A of the wafer 100. Note that such cutting can be performed by a known method. For example, a portion of the outer edge portion of the region A along the Y-axis direction (that is, a portion of the region A along the cleavage lines L1 on both sides in the X-axis direction) can be cleaved by processing similar to the primary cleavage to be described later. In addition, a portion of the outer edge portion of the region A along the X-axis direction can be cut by performing a breaking processing of pressing and breaking the wafer 100 by applying a breaking blade from the back surface (second primary surface 100b) of the wafer 100 after it has been scribed by diamond scribing or the like.

[0074] Subsequently, the processing (primary cleavage) of cleaving the wafer 100 (in the present embodiment, the square plate-shaped member obtained by the method described above) is performed along each of the plurality of cleavage lines L1. As a result, the plurality of laser bars LB (see Fig. 13) are obtained, each comprising a plurality of device sections C arranged one-dimensionally in the Y-axis direction. The above primary cleaving is carried out, for example, by performing the breaking process of pressing and breaking the wafer 100 by applying the breaking blade from the back side (second primary surface 100b) of the wafer 100 along the cleavage line L1 as described above. (Fifth step: secondary cleavage step)

[0075] Subsequently, the processing (secondary cleavage or component division) of cleaving each of the plurality of laser bars LB along each of the plurality of component division lines L2 is carried out. As a result, as shown in Fig. 13, a plurality of semiconductor laser devices 1A are obtained from each laser bar LB. The above secondary cleavage is performed, for example, by performing the breaking process of pressing and breaking the wafer 100 by applying the breaking blade from the back side (second primary surface 100b) of the laser bar LB along the device division line L2 as described above. [Effects]

[0076] In the method for manufacturing the semiconductor laser device 1A, the device dividing groove 20 for the secondary cleavage (fifth step) is formed in a wafer state at a stage (second step) before the plurality of laser bars LB are obtained by the primary cleavage (fourth step). As a result, it is not necessary to perform scribe processing for each laser bar LB using a diamond tool, a laser, or the like as pre-processing for the secondary cleavage (fifth step) after the primary cleavage (fourth step). In addition, since one man-hour of the second step (i.e., the processing for forming the device dividing groove 20 in the wafer state) is less than one man-hour required to perform the scribe processing for each laser bar LB as described above, it is possible to reduce one man-hour by the manufacturing process.In addition, since the component division groove 20 is formed by etching, a deep damage layer, which is generated when dot scribing (diamond scribing) or the like is performed, is not formed at a distal end portion (bottom portion) of the component division groove 20 in the Z-axis direction. As a result, it is possible to sufficiently ensure the strength of the wafer 100 after the component division grooves 20 are formed. As a result, even when back-side processing or the like of the wafer 100 is performed after the second step, damage to the wafer 100 is adequately prevented. Furthermore, in the case where dot scribing is performed, problems such as debris scattering and the occurrence of lateral cracks may occur, but it is possible to reliably avoid the above-mentioned problems by forming the component division grooves 20 by etching.In addition, the component division groove 20 (etching groove) is not formed on the cleavage line L1, and the cleavage introduction groove 30 is also mainly formed outside the component region A1. That is, the groove is not formed on the cleavage line L1 in the component region A1. This makes it possible to suppress the occurrence of cracks (cracks developing in the X-axis direction) caused by the groove in the laser bar LB obtained by the primary cleavage (fourth step). In addition, the semiconductor substrate 2 made of GaAs (ie, the substrate layer 2L made of GaAs), which is relatively easily cracked, is used, and therefore, the primary cleavage (fourth step) along the cleavage line L1 can be performed easily and accurately by providing the cleavage introduction groove 30 outside the component region A1.Accordingly, according to the above manufacturing method, it is possible to reduce the manufacturing man-hours without affecting the manufacturing quality of the semiconductor laser device 1A.

[0077] Furthermore, the gap introduction groove 30 is not formed within the component region A1 (specifically, the region between the component sections C adjacent to each other in the X-axis direction on the cleavage line L1). That is, neither the component division groove 20 nor the gap introduction groove 30 is formed on the cleavage line L1 in the component region A1. As a result, it is possible to more effectively suppress the occurrence of cracks in the laser bar LB during the primary cleavage (fourth step) described above.

[0078] Furthermore, the component division groove 20 is formed in the first primary surface 100a, penetrates the semiconductor layer 3L, and reaches the substrate layer 2L. At least a portion of the inner surface 20a of the component division groove 20 formed by the semiconductor layer 3L is inclined with respect to the Z-axis direction, so that the width of the component division groove 20 decreases in the Y-axis direction from the first primary surface 100a side to the second primary surface 100b side. According to the above configuration, in a case where the portion of the inner surface 20a of the device division groove 20 formed by the semiconductor layer 3L functions as a side surface of a mesa light-emitting portion of the semiconductor laser device 1A, it is possible to appropriately suppress the oscillation of the mesa light-emitting portion in a lateral direction (oscillation in the Y-axis direction).Furthermore, the component dividing groove 20 reaches the substrate layer 2L, allowing only the substrate layer 2L to be divided during the secondary cleavage (fifth step). This makes it possible to reduce the risk of cracks occurring within the semiconductor layer 3L at the time of secondary cleavage or of the semiconductor layer 3L detaching from the substrate layer 2L.

[0079] Moreover, the inner surface 20a of the first portion 21 is inclined with respect to the Z-axis direction, so that the width of the component division groove 20 in the Y-axis direction decreases from the first primary surface 100a side to the second primary surface 100b side, the inclination angle θ1 of the inner surface 20a of the first portion 21 with respect to the Z-axis direction is larger than the inclination angle (about 0 degrees in the present embodiment) of the inner surface 20a of the second portion 22 with respect to the Z-axis direction, and the first portion 21 penetrates the semiconductor layer 3L and reaches the substrate layer 2L. According to the above configuration, the inner surface 20a of the first portion 21 of the component dividing groove 20 is inclined with respect to the Z-axis direction, and therefore it is possible to easily divide the laser bar LB along the component dividing line L2 in the secondary cleavage (fifth step).Specifically, the width of the first portion 21 in the Y-axis direction is formed in a shape that expands toward the opening side of the component division groove 20, and thereby, it is possible to increase the volume of the component division groove 20. As a result, it is possible to easily break the laser bar LB along the component division groove 20. On the other hand, in a case where the entire inner surface 20a of the component division groove 20 is inclined at a substantially constant inclination angle with respect to the Z-axis direction, it is difficult to accurately align the central position of the bottom portion of the component division groove 20 on the component division line L2, and there is a concern that the component division cannot be accurately performed.Therefore, as described above, the second portion 22 is provided with a gentler inclination with respect to the Z-axis direction than the first portion 21 on the bottom portion side of the component division groove 20, and thereby it is possible to accurately align the central position of the bottom portion of the component division groove 20 on the component division line L2. Accordingly, according to the above configuration, it is possible to shorten a time required for component division by facilitating component division (secondary splitting) by the first portion 21, and it is possible to improve the accuracy of component division by accurately controlling a component division position by the second portion 22.

[0080] Moreover, the inner surface 20a of the first portion 21 of the device division groove 20 forms the side surface of the mesa light-emitting portion of each of the plurality of device portions C, and the first portion 21 penetrates the semiconductor layer 3L and reaches the substrate layer 2L. According to the above configuration, since the side surface of the mesa light-emitting portion is formed as an inclined surface inclined with respect to the Z-axis direction, it is possible to appropriately suppress oscillation of the mesa light-emitting portion in the lateral direction (oscillation in the Y-axis direction).

[0081] In addition, the bottom portion of the component dividing groove 20 has the bottom surface 23 extending in the Y-axis direction. According to the above configuration, it is possible to increase the mechanical strength of the wafer 100 compared to a case where the component dividing groove 20 is formed in the V-shape. As a result, in a case where back-side processing or the like is performed on the wafer 100 after the component dividing grooves 20 are formed, it is possible to suppress damage to the wafer 100 and improve yield. In addition, since the accuracy of etching deteriorates with increasing inclination, in a case where the component dividing groove 20 is formed in a V-shape (ie,In a case where the entire inner surface 20a of the component division groove 20 is formed as the inclined surface), it is difficult to control the shape of the component division groove 20 formed by etching, and as a result, there is a concern that a division direction (a direction along a division surface) at the time of component division becomes unstable (that is, the division surface is not parallel to the Z-axis direction). On the other hand, etching is performed so that the component division groove 20 has the bottom surface 23, and thus the shape of the component division groove 20 can be controlled more precisely than in a case where the component division groove 20 is formed in a V-shape. As a result, the accuracy of the component division can be improved.

[0082] Moreover, the width of the bottom surface 23 of the component dividing groove 20 in the Y-axis direction is 10 μm or less. According to the above configuration, the width of the bottom surface 23 is suppressed to a certain value or less (10 μm or less), and thus, it is possible to easily divide the device along the component dividing groove 20 while obtaining the effect of a case where the component dividing groove 20 has the bottom surface 23 as described above. That is, the width of the bottom surface 23 can be large from the viewpoint of ensuring the mechanical strength of the wafer 100. However, if the width of the bottom surface 23 is too large, the laser bar LB is hardly broken along the component dividing groove 20 at the time of component division. According to the above configuration, it is possible to suppress such a disadvantage.

[0083] Furthermore, the inner surface 20b of the component division groove 20 is inclined in the X-axis direction with respect to the Y-axis direction, so that the inner surface 20b becomes narrower toward the substantially central portion of the component division groove 20 in the Y-axis direction toward the outside in the X-axis direction. According to the above configuration, it is possible to easily divide the device along the substantially central portion of the component division groove 20 in the Y-axis direction, compared to a case where the shape of the component division groove 20 is a simple rectangular shape when viewed from the Z-axis direction.

[0084] Furthermore, the method for manufacturing the semiconductor laser device 1A as shown in Fig.11, a step of forming the insulating film 4 after the second step and before the third step, and forming the electrode 5 that contacts the upper surface 3La of the semiconductor layer 3L via the opening portion 4a of the insulating film 4 and covers at least a part of the portion of the insulating film 4 that covers the upper surface 3La. According to the above configuration, in a case where the portion of the inner surface 20a of the device division groove 20 formed by the semiconductor layer 3L functions as the side surface of the mesa light-emitting portion of the semiconductor laser device 1A obtained after the device division, since the side surface of the mesa light-emitting portion can be appropriately protected by the insulating film 4, it is possible to suppress the occurrence of dark line defects due to damage to the side surface of the mesa light-emitting portion.Furthermore, the electrode 5 is formed on the top surface 3La of the semiconductor layer 3L over the insulating film 4, and this makes it possible to further improve the adhesion of the electrode 5. This makes it possible to improve the manufacturing quality of the semiconductor laser device 1A.

[0085] In addition, since the semiconductor laser device 1A described above has a configuration that can be manufactured easily and accurately by the above-described manufacturing method, it is possible to improve the yield. Furthermore, in a case where the side surface 3b of the semiconductor stack body 3 functions as the side surface of the mesa light-emitting portion, it is possible to appropriately suppress the oscillation of the mesa light-emitting portion in the lateral direction (oscillation in the Y-axis direction) because the side surface 3c is formed as the inclined surface inclined with respect to the Z-axis direction. [Modification examples](Modification example of the component division groove)

[0086] The shape of the component division groove formed in the second step is not limited to the shape of the above-described component division groove 20. For example, the component division groove formed in the second step may be formed in a simple rectangular parallelepiped shape (rectangular shape viewed in the Z-axis direction). Furthermore, instead of the above-described component division groove 20, a component division groove 20A according to a Fig.14. An inner surface 20Aa of the component dividing groove 20A in the Y-axis direction does not have a portion corresponding to the second portion 22 of the component dividing groove 20, but has only a portion corresponding to the first portion 21 of the component dividing groove 20. That is, the entire inner surface 20Aa of the component dividing groove 20A is inclined with respect to the Z-axis direction. On the other hand, similar to the inner surface 20b of the component dividing groove 20, an inner surface 20Ab of the component dividing groove 20A in the X-axis direction is inclined with respect to the Y-axis direction so as to become narrower toward a substantially central portion of the component dividing groove 20A in the Y-axis direction outward in the X-axis direction. In addition, the inner surface 20Ab in the component dividing groove 20A has an R-shape (i.e.,a convex and outwardly rounded shape) as viewed from the Z-axis direction. According to the above configuration, it is possible to obtain an effect (i.e., an effect capable of easily dividing the component substantially along the central portion of the component dividing groove 20 in the Y-axis direction) similar to the inner surface 20b of the component dividing groove 20. Moreover, the inner surface 20Ab is formed in the R-shape, and thereby it is possible to reduce the risk of cracks occurring in the inner surface 20Ab compared to a case where the inner surface 20Ab is formed in a square shape. (First modification example of a semiconductor laser device)

[0087] Fig. 15 is a cross-sectional view of a semiconductor laser device 1B according to a first modification example. As in Fig.15, the semiconductor laser device 1B differs from the semiconductor laser device 1A in that the insulating film 4 is not provided. The semiconductor laser device 1B can be manufactured by modifying part of the above-described method for manufacturing the semiconductor laser device 1A. For example, the semiconductor laser device 1B can be obtained by omitting the process of forming the insulating film 4 in the front-surface processing step of the above-described method for manufacturing the semiconductor laser device 1A. Moreover, in a case where the semiconductor laser device 1B is manufactured, it is not necessary to form the insulating film 4 after forming the device division groove 20. That is, in a case where the semiconductor laser device 1B is manufactured, the front-surface processing step (forming process of the electrode 5) can be performed before the second step. (Second modification example of a semiconductor laser device)

[0088] Fig. 16 is a cross-sectional view of a semiconductor laser device 1C according to a second modification example. As shown in Fig.16, the semiconductor laser device 1C differs from the semiconductor laser device 1A in that a pair of semiconductor stacked bodies 3B that do not function as a mesa light-emitting portion are provided on both sides of a semiconductor stacked body 3A that functions as a mesa light-emitting portion in the Y-axis direction, with a groove G interposed therebetween. In the semiconductor laser device 1C, the insulating film 4 is provided on the front surfaces of the semiconductor stacked body 3A and the pair of semiconductor stacked bodies 3B, and the insulating film 4 is provided with an opening portion 4a that exposes the top surface 3a of the semiconductor stacked body 3A. Furthermore, the electrode 5 is provided from an upper portion of one semiconductor stacked body 3B via the semiconductor stacked body 3A to an upper portion of the other semiconductor stacked body 3B.In the semiconductor laser device 1C, an outer side surface 3b of each of the two semiconductor stacked bodies 3B in the Y-axis direction and the first portion 2c1 and the second portion 2c2 of the side surface 2c of the semiconductor substrate 2 correspond to the inner surface 20a of the device division groove 20 formed in the second step. The semiconductor laser device 1C can be manufactured by modifying part of the above-described method for manufacturing the semiconductor laser device 1A. For example, the front-side processing step may be performed before the second step. Here, the front-side processing step includes the mesa formation process for forming the mesa light-emitting portion (semiconductor stacked body 3A) by forming the groove G in the semiconductor layer 3L and forming the insulating film 4 and the electrode 5.The semiconductor laser device 1C can be obtained by performing the second step, the back-side processing step, the third step, the fourth step, and the fifth step similar to the steps in the method for manufacturing the semiconductor laser device 1A after performing such a front-side processing step. According to the semiconductor laser device 1C, it is possible to suppress the occurrence of the above-described dark line defects by covering the side surface of the semiconductor stack body 3A, which functions as the mesa light-emitting portion, with the insulating film 4, while the front-side processing step can be performed before the second step. (Other modification examples)

[0089] Although the above embodiment and some modification examples of the present disclosure have been described above, the present disclosure is not limited to the configurations described in the above embodiment and modification examples. The material and shape of each configuration are not limited to the material and shape described above, and materials and shapes other than the material and shape described above may also be used. Furthermore, some configurations included in the above embodiment and modification examples may be appropriately omitted or changed, or may be arbitrarily combined.

[0090] For example, in the above embodiment, in the fourth step (primary cleavage step), the processing of cutting out the square plate-shaped member including only the area A from the disc-shaped wafer 100 is performed first, but such processing may be omitted. That is, the wafer 100 may be directly cleaved along each of the plurality of cleavage lines L1. In this case, the cleavage introduction groove 30 formed on each cleavage line L1 may be provided at an end portion of the wafer 100 in the Y-axis direction.

[0091] Furthermore, after the fourth step (primary cleavage step), a pair of end faces of the laser bar LB in the X-axis direction may be coated. For example, an anti-reflection film (low-reflection film) may be provided on an end face serving as the emission end face of the laser beam L among the pair of end faces of the laser bar LB in the X-axis direction. On the other hand, a highly reflective film may be provided on an end face opposite the end face serving as the emission end face of the laser beam L among the pair of end faces of the laser bar LB in the X-axis direction.

[0092] Moreover, the above-described effect of the first portion 21 and the second portion 22 of the component dividing groove 20 (that is, the effect capable of shortening the time required for component division by facilitating component division (secondary cleavage) by the first portion 21 and improving the accuracy of component division by precisely controlling the component division position by the second portion 22) can be obtained even in a case where the step of forming the component dividing groove (second step) is performed on the laser bar LB (semiconductor element) obtained after the primary cleavage step (fourth step).

[0093] Furthermore, in the above embodiment, both the component division groove 20 and the gap insertion groove 30 are formed in the first primary surface 100a, but may be formed in the second primary surface 100b. Furthermore, a primary surface on which the component division groove 20 is formed and a primary surface on which the gap insertion groove 30 is formed may be different from each other.

[0094] Moreover, in the above embodiment, although the shape in which the inclination angle of the inner surface 20a of the second portion 22 with respect to the Z-axis direction is approximately 0 degrees (that is, the shape in which the inner surface 20a of the second portion 22 is substantially parallel to the Z-axis direction) has been exemplified, the inner surface 20a of the second portion 22 may be inclined with respect to the Z-axis direction within a range in which the inclination angle is smaller than the inclination angle θ1 of the inner surface 20a of the first portion 21.

[0095] Moreover, in the above embodiment, although the gap insertion groove 30 is formed only outside the component region A1, a part of the gap insertion groove 30 may be included within the component region A1. In this case, for example, the length of the portion of the gap insertion groove 30 included outside the component region A1 in the Y-axis direction may be longer than the length of the portion of the gap insertion groove 30 included inside the component region A1 in the Y-axis direction. Even in such a configuration, since most of the gap insertion groove 30 is formed outside the component region A1, the portion of the gap insertion groove 30 formed inside the component region A1 is smaller than the portion of the gap insertion groove 30 formed outside the component region A1.As a result, it is possible to suppress the occurrence of the crack caused by the gap introduction groove 30 in the laser bar LB obtained by the primary cleavage (fourth step).

[0096] Furthermore, the method for manufacturing a semiconductor laser device of the present disclosure can be applied to a method for manufacturing a superluminescent diode (SLD). That is, a process similar to the step of the present disclosure can be performed on a wafer used for manufacturing the SLD. This achieves similar effects to those of the method for manufacturing a semiconductor laser device of the present disclosure. For example, it is possible to suppress lateral stress cracks in the resulting SLD. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-22487

[0002] JP 2003-17791 [0003, 0004]

Claims

[1] A method of manufacturing a semiconductor laser device comprising a semiconductor substrate made of GaAs and a semiconductor stack body comprising an active layer and stacked on the semiconductor substrate, the method comprising: a first step of preparing a wafer including a plurality of device sections, each of which will become the semiconductor laser device, and including a substrate layer including the semiconductor substrate of each of the plurality of device sections and a semiconductor layer including the semiconductor stacked body of each of the plurality of device sections, wherein, in the wafer, the plurality of device sections are arranged in a matrix in a first direction parallel to an optical waveguide direction of the semiconductor stacked body and a second direction perpendicular to the first direction, viewed from a thickness direction of the wafer; a second step of forming a component division groove by etching on a first primary surface on a side of the wafer on which the semiconductor layer is positioned with respect to the substrate layer or a second primary surface opposite to the first primary surface along a component division line extending in the first direction to divide the plurality of component sections arranged in the second direction; a third step of forming a gap introduction groove to become a starting point of a gap on the first primary surface or the second primary surface at a position overlapping a gap line extending in the second direction to divide the plurality of component sections arranged in the first direction after the second step; a fourth step of obtaining a plurality of laser bars comprising a plurality of device sections arranged one-dimensionally in the second direction by cleaving the wafer along the cleavage line; and a fifth step of splitting each of the plurality of laser bars along the component division line, wherein in the second step, the component dividing groove is not formed on the split line, and in the third step, the gap introduction groove is formed only outside a component region in which the plurality of component sections are arranged, or is formed such that a length of a portion of the gap introduction groove included outside the component region in the second direction is longer than a length of a portion of the gap introduction groove included inside the component region in the second direction. [2] A method of manufacturing a semiconductor laser device according to claim 1, wherein in the third step, the gap introduction groove is formed only outside the device region. [3] A method for manufacturing a semiconductor laser device according to claim 1 or 2, wherein the component division groove is formed on the first primary surface, penetrates the semiconductor layer and reaches the substrate layer, and at least a portion of a first inner surface of the component dividing groove formed by the semiconductor layer in the second direction is inclined with the thickness direction so that a width of the component dividing groove in the second direction decreases from the first primary surface side to the second primary surface side. [4] A method for manufacturing a semiconductor laser device according to claim 3, wherein the component dividing groove has a first portion positioned on an opening side of the component dividing groove and a second portion positioned on a bottom portion side of the component dividing groove with respect to the first portion, the first inner surface of the first portion is inclined with respect to the thickness direction such that the width of the component dividing groove decreases in the second direction from the first primary surface side to the second primary surface side, an inclination angle of the first inner surface of the first portion with respect to the thickness direction is greater than an inclination angle of the first inner surface of the second portion with respect to the thickness direction, and the first section penetrates the semiconductor layer and reaches the substrate layer. [5] A method of manufacturing a semiconductor laser device according to any one of claims 1 to 4, wherein a bottom portion of the device dividing groove has a bottom surface extending in the second direction. [6] A method of manufacturing a semiconductor laser device according to claim 5, wherein a width of the bottom surface of the device division groove in the second direction is 20 µm or less. [7] A method of manufacturing a semiconductor laser device according to any one of claims 1 to 6, wherein the etching is a dry etching using a chlorine-based gas. [8] A method for manufacturing a semiconductor laser device according to any one of claims 1 to 7, wherein a second inner surface of the device dividing groove in the first direction is inclined with respect to the second direction to become narrower toward a substantially central portion of the device dividing groove in the second direction toward an outer side in the first direction. [9] A method of manufacturing a semiconductor laser device according to claim 8, wherein the second inner surface of the device dividing groove is formed in an R-shape as viewed from the thickness direction. [10] A method for manufacturing a semiconductor laser device according to any one of claims 1 to 9, wherein an extending direction of the device division line is parallel to a [01-1] direction of the substrate layer. [11] A method of manufacturing a semiconductor laser device according to any one of claims 1 to 10, wherein the device dividing groove and the gap introduction groove are formed in the first primary surface. [12] A method for manufacturing a semiconductor laser device according to any one of claims 1 to 11, wherein the second step comprises a step of forming a resistance film, wherein an opening portion overlapping a region including a central portion of a predetermined region in which the component division groove is formed is provided on a primary surface of the first primary surface or the second primary surface of the wafer on which the component division groove is formed before etching, and a thickness of the resistance film is formed at a peripheral edge portion of the opening portion to become thinner toward an end portion of the opening portion along the second direction. [13] A method for manufacturing a semiconductor laser device according to any one of claims 1 to 12, further comprising: a step of forming an insulating film provided to cover a top surface of the semiconductor layer of the wafer and an inner surface of the device division groove, wherein an opening portion in which a part of the top surface is exposed is provided in the insulating film, and forming an electrode covering at least a part of a portion of the insulating film that is in contact with the top surface via the opening portion and covers the top surface, after the second step and before the third step.

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