JP4799847B2 - Semiconductor laser device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor laser device and a method for manufacturing the same, for example, a technology effective when applied to a visible laser diode (LD) manufacturing technology with an output Po of 10 mW or more.

  Semiconductor lasers (LDs) are widely used as light sources for optical communication systems and information processing equipment. Visible light semiconductor lasers are used as light sources for information processing equipment such as document file systems such as CD, VD equipment, laser printers, POS, and barcode readers.

Along with an increase in processing capability of information processing equipment, a semiconductor laser as a light source is required to have a higher output. When the output Po is 10 mW or more, light damage (COD: Catastrophic Optical Damage) occurs on the emission surface that emits laser light, and laser light emission cannot be continued. Therefore, conventionally, a technique has been adopted in which zinc diffusion is performed on the end face portion of the resonator of the semiconductor laser to form a window structure to prevent destruction on the emission surface (for example, Patent Document 1).
In addition, a structure has been proposed in which a current non-injection region is provided in the vicinity of the end face to suppress the temperature rise of the end face and prevent the generation of COD (for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 11-68217 JP 2003-158339 A

  The window structure by selective diffusion of Zn, which is adopted as a countermeasure against COD, diffuses zinc (Zn) in the vicinity of the emission surface, which also serves as the end face of the resonator of the semiconductor laser chip, and forms an MQW (multiple quantum well layer) as an active layer ) To increase the Eg (energy band gap) and make the end face transparent to the oscillation wavelength, thereby improving the COD level.

  However, the window structure based on Zn diffusion not only requires an additional process, but also causes problems such as an increase in the semiconductor laser threshold (Ith) due to Zn diffusion. In order to avoid the problem in the window structure due to Zn diffusion, a structure in which the vicinity of the end face is not current-injected has been proposed. However, it has been found that the window structure which is a current non-injection structure near the end face has the following problems. The semiconductor laser chip is formed by dividing the wafer vertically and horizontally. Since the emission surface of the semiconductor laser element (semiconductor laser chip) that emits the laser light needs to be a laser light reflecting mirror, it is formed by cleaving the semiconductor substrate (crystal). For this reason, the cleavage line is not constant and varies. Due to this variation in cleavage, the length of the non-injection portion varies, and the variation is large. It has been found that when the variation becomes as large as, for example, 7 μm or more, adverse effects occur. Since the cleaving of the semiconductor substrate is performed by applying a sharp cutter to one edge of the substrate, the cleaving line on the design varies, for example, about 10 μm at the maximum.

  When the non-injection part becomes long due to variation in cleavage, IL kink occurs due to supersaturated absorption. Moreover, if the non-injection part is too short, the effect of suppressing the temperature rise is reduced. For this reason, a stable COD countermeasure becomes difficult.

An object of the present invention is to provide a semiconductor laser device in which IL kink hardly occurs and a method for manufacturing the same.
Another object of the present invention is to provide a semiconductor laser capable of suppressing optical damage on the cavity end face of the semiconductor laser and a method for manufacturing the same.
The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The outline of a typical invention among the inventions disclosed in the present application will be briefly described as follows.

  (1) A semiconductor laser element includes a semiconductor substrate (n-type GaAs substrate) having a first conductivity type, an active layer (a barrier layer made of AlGaInP) and a well made of AlGaInP or InGaP provided on the upper surface of the semiconductor substrate. A multiple quantum well structure in which multiple layers are formed), a semiconductor layer (p-type AlGaInP layer) of the second conductivity type formed on the active layer, and the semiconductor substrate formed on the semiconductor layer And an electrode for injecting current into the active layer portion of the resonator, corresponding to the end of the elongated resonator formed by the active layer and the semiconductor layer. On at least one end side of the resonator, a non-injection portion made of an insulator that prevents injection of current into the active layer and an injection portion that injects current into the active layer are extended by the resonator. And it is provided periodically along the direction. The semiconductor laser element includes two grooves provided so as to reach a halfway depth from the upper surface of the semiconductor layer, a mesa composed of the semiconductor layer formed between the two grooves, and the mesa And an insulating film provided on the upper surface of the semiconductor layer except for the upper surface of the semiconductor layer, the electrode is electrically connected to the upper surface of the mesa, and the lower portion of the mesa constitutes the resonator. The non-injection part is provided between the mesa formed by the semiconductor layer and the electrode, and is formed by an insulating film that crosses the resonator. The non-injection parts are arranged at a constant length and a constant pitch.

Such a semiconductor laser device is manufactured by the following method. The semiconductor laser element is
(A) preparing a semiconductor substrate (n-type GaAs substrate) of the first conductivity type;
(B) forming an active layer (a multiple quantum well structure in which multiple barrier layers made of AlGaInP and well layers made of AlGaInP or InGaP) are formed on the upper surface of the semiconductor substrate;
(C) forming a semiconductor layer (p-type AlGaInP layer) of the second conductivity type on the active layer;
(D) Two grooves are formed at a predetermined interval so as to remove the semiconductor layer, and a plurality of protruding mesas sandwiched between the two grooves are formed on the active layer. A step of configuring a resonator in
(E) forming an insulating film covering the top surface of the semiconductor substrate except for the top surface of the mesa;
(F) forming an electrode selectively formed on the insulating film and partially overlapping the mesa;
(G) forming an electrode on the lower surface of the semiconductor substrate;
(H) dividing the semiconductor substrate and each layer on the semiconductor substrate between the mesa and the mesa and cleaving at a predetermined interval in a direction orthogonal to the mesa to form a plurality of rectangular semiconductor laser elements;
Performed before the step (h) for performing the splitting and the cleaving. (I) Injecting current into the active layer in a planned cleavage region including a predetermined length region on both sides of the cleavage line for performing the cleavage. And a step of periodically providing a non-injection portion made of an insulating material along the extending direction of the resonator.

  In addition, an insulating film formed on the semiconductor layer is selectively formed between the mesa and the electrode to form the non-injection portion. The non-injection portions are arranged at a constant length and a constant pitch.

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  According to the means (1), (a) a region (injection portion) for supplying current to the pn junction forming the resonator and a region (non-injection portion) for supplying no current form the resonator end face. It is periodically provided in a fixed area including the area to be operated. Therefore, when the semiconductor substrate is cleaved, even if the cleavage position varies widely, the injection portion and the non-injection portion are alternately provided in the vicinity of the cleavage surface. There is no variation.

  In particular, when there are a plurality of injection portions in the size region where the cleavage position varies, the ratio of increase / decrease of the non-injection portion to the variation in the cleavage position becomes small.

  The length of the non-injection part according to the present invention is about 5 μm. As a result, it is possible to suppress the generation of IL kink due to supersaturated absorption that occurs when the non-injection part is too long, such as 7 μm or more, and it is possible to suppress optical damage (COD).

  (B) In the method of manufacturing a semiconductor laser device according to the present invention, in the step (e) of forming an insulating film that covers the upper surface of the semiconductor substrate excluding the upper surface of the mesa, a part of the insulating film is partially provided on the mesa. The non-injection part is formed by the insulating film part provided partially. Therefore, in manufacturing, the insulating film for forming the non-implanted portion can be manufactured only by changing the photomask for patterning the insulating film, and the number of processes does not increase. As a result, an increase in the manufacturing cost of the semiconductor laser element can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments of the invention, those having the same function are given the same reference numerals, and their repeated explanation is omitted.

  1 to 15 are diagrams related to a semiconductor laser device which is Embodiment 1 of the present invention. 1 to 4 are diagrams related to the structure of the semiconductor laser device, and FIGS. 5 to 14 are diagrams related to a method of manufacturing the semiconductor laser device. FIG. 15 is a perspective view in which a part of the semiconductor laser device incorporating the semiconductor laser element of Example 1 is cut away.

  In Example 1, an example in which the present invention is applied to the manufacture of a 0.6 μm band red semiconductor laser (semiconductor laser element) will be described. In the first embodiment, an example of a semiconductor laser element having a wavelength of 630 nm band of n-type (N-type) as the first conductivity type and p-type (P-type) as the second conductivity type will be described.

  The semiconductor laser device 1 of Embodiment 1 has a structure shown in FIGS. FIG. 1 is a schematic perspective view showing the appearance of the semiconductor laser device 1, and FIGS. 2A to 2C are cross-sectional views taken along lines AA, BB, and CC in FIG. is there.

  As shown in FIGS. 1 and 2, the semiconductor laser element (semiconductor laser chip) 1 is manufactured based on a semiconductor substrate 2 having a thickness of about 100 μm. The semiconductor substrate 2 is, for example, an n-type GaAs substrate 2. As shown in FIG. 2, an active layer 3 and a semiconductor layer 4 made of p-type AlGaInP are formed on the main surface (the upper surface in FIGS. 1 and 2) of the n-GaAs substrate 2. The active layer 3 has a multiple quantum well structure in which a 5 nm thick barrier layer made of AlGaInP and a 12 nm thick well layer made of InGaP are formed in multiple layers. There are three well layers. The semiconductor layer 4 has a thickness of about 1 μm. Note that an n-type GaAs layer may be provided on the main surface of the semiconductor substrate 2 by epitaxial growth, and the active layer 3 may be formed on the n-type GaAs layer.

  As shown in FIGS. 1 and 2C, two grooves 5 a and 5 b are provided on the upper surface of the semiconductor layer 4 in parallel. The grooves 5a and 5b are deep enough to reach the vicinity of the active layer 3. For example, the thickness of the semiconductor layer 4 at the bottom of the grooves 5a and 5b is about 1 μm. A portion sandwiched between the pair of grooves 5a and 5b is a protruding mesa (projection) 6 made of p-type AlGaInP. The width of the mesa 6 is about 2 μm, and the width of the grooves 5a and 5b is about 10 μm.

  An insulating film 7 is provided on the upper surface of the semiconductor laser element 1. As shown in FIG. 2C, the insulating film 7 covers the side surface of the mesa 6, the grooves 5a and 5b, and the semiconductor layer 4 located outside the grooves 5a and 5b. Further, as shown in FIGS. 2A, 3 and 4A, 4B, the insulating film 7 is formed on the upper surface of the mesa 6 so as to cross the mesa 6 at the end of the elongated mesa 6. Is formed. The insulating film 7 that crosses the mesa 6 and covers the upper surface of the mesa 6 is also referred to as a current non-injection insulating film 7a for convenience of explanation. In FIG. 4A, the dotted portions are regions where the insulating film 7 is provided, and the insulating film portion that covers the mesa 6 having the width a is the insulating film 7 that blocks current injection, ie, current non-injection. This is the insulating film 7a. FIG. 3 shows an enlarged portion of the current non-injection insulating film 7a. In FIG. 2A, three current non-injection insulating films 7a are shown on the right end side and four on the left end side. The right end shows a state in which cleavage is performed in the injection portion between the current non-injection insulating film 7a and the current non-injection insulating film 7a, and the left end shows a state in which cleavage is performed in the current non-injection insulating film 7a. In the drawing, the current non-injection insulating films 7a are shown as three or four for convenience of explanation, but may be more.

  On the insulating film 7, as shown in FIGS. 1, 2A, and 2C, a conductor layer 9 is formed in a predetermined pattern. In FIG. 1, the conductor layer 9 is indicated by a dotted area. One of the conductor layers 9 overlaps the upper surface of the mesa 6 and is electrically connected to the mesa 6 as shown in FIGS. 1 and 2C. The conductor layer 9 forms an electrode (p electrode) 10. As shown in FIGS. 2 (c) and 1, the electrode (p electrode) 10 is provided with a constant width b (see FIG. 4) over the entire length of the mesa 6, and crosses one groove 5b. It is provided so as to extend onto the right insulating film 7 which is out of the groove 5b. The electrode portion that is formed largely on the right insulating film 7 outside the groove 5b constitutes, for example, a bonding pad 10c that connects wires.

  An independent conductor layer 9a is also formed on the left insulating film 7 that is removed from the groove 5a. The conductor layer 9a and the electrode (p electrode) 10 are used as a connecting conductor layer when the semiconductor laser element 1 is fixed to a substrate such as a heat sink in a junction-down state (with the pn junction facing down). An electrode portion having a width b (see FIG. 4) provided to overlap the mesa 6 in order to improve the connection state is also overlapped with a constant width on the outer edges of the grooves 5a and 5b. By doing so, the heat generated in the semiconductor laser element 1 can be quickly transferred to the heat sink via the electrode (p electrode) 10 and the conductor layer 9a.

In addition, triangular marks 9 b are provided in the vicinity of both ends of the semiconductor laser element 1. The mark 9b is used as a guide when the semiconductor laser device 1 is manufactured by cleaving the wafer.
An electrode (n electrode) 11 is formed on the lower surface of the semiconductor substrate 2. The electrode (n electrode) 11 is provided over the entire lower surface of the semiconductor substrate 2.

  The elongated region formed by the semiconductor substrate 2 portion, the active layer 3 portion, and the semiconductor layer 4 portion corresponding to the mesa 6 forms a resonator. Therefore, by applying a predetermined voltage between the p-electrode 10 and the n-electrode 11, the laser light 15 is emitted from both end surfaces (emission surfaces) of the resonator. Although not shown, generally, films having a predetermined refractive index are formed on both emission surfaces, and the output of the emitted laser light is different. The side with the larger output is used as the front emission surface, and the side with the smaller output is used as the rear emission surface, which is used as a surface for extracting light for monitoring the laser light intensity.

  As shown in FIG. 4A, the current non-injection insulating film 7a is provided on the end face side of the semiconductor laser device 1 along the extending direction of the resonator (the extending direction of the mesa 6). In the first embodiment, the length of the non-injection portion formed by the current non-injection insulating film 7a along the extending direction of the resonator, the mesa 6 between the non-injection portion and the non-injection portion, and the electrode (p electrode) 10 The lengths along the extending direction of the resonator of the injection portion, which is a region in contact with each other, are the same.

  Since the current non-injection insulating film 7a is a non-injection portion that does not pass current, no current is supplied to the active layer 3 directly below the current non-injection insulating film 7a, and the current density of the resonator end face is reduced. Can do.

  In the manufacture of the semiconductor laser device 1, when the semiconductor substrate 2 or the like (wafer) is cleaved, the actual cleavage position varies, for example, by about 10 μm at maximum with respect to the designed cleavage line. Therefore, in the first embodiment, the length of the non-injection portion is 5 μm, and even when cleaving is performed with a large variation of 10 μm, one or two injection portions are present in the deviation length region of this variation, The variation dimension does not directly increase or decrease the non-injection portion. Thereby, generation | occurrence | production of IL kink by the supersaturated absorption which generate | occur | produces when a non-injection part is too long as 7 micrometers or more can be prevented, and optical damage (COD) can be prevented.

  Next, a method for manufacturing the semiconductor laser device 1 will be described with reference to FIGS. In manufacturing the semiconductor laser device 1, a wafer (semiconductor substrate) 20 is prepared as shown in FIG. The wafer 20 is sequentially processed in each manufacturing process, and is formed into the semiconductor laser element 1 by dividing and cleaving in the final process. Accordingly, the wafer 20 at the stage of initial preparation is the semiconductor substrate 2 itself that constitutes the semiconductor laser element 1. For convenience of explanation, in the explanation of each process, manufacture of a single semiconductor laser element will be explained. Accordingly, in the description of each process, the description will be made with only a part of the drawings.

The wafer 20 is composed of an n-conductivity type (first conductivity type) GaAs substrate having a thickness of several hundred μm. This wafer 20 has Si as an impurity, and has an impurity concentration of about 2.0 × 10 ¹⁸ cm ⁻³ . The main surface of the semiconductor substrate 12 is a (100) crystal plane.

  Next, a semiconductor layer is sequentially formed on the main surface (upper surface) side of the wafer 20 by MOCVD (Metal Organic Chemical Vapor Deposition) method or MBE (Molecular Beam Epitaxy) method to form a multi-layer semiconductor layer. These semiconductor layers are the active layer 3 and the semiconductor layer 4 described above. After that, as shown in FIG. 5, two grooves 5a and 5b are formed at a predetermined interval by a conventional photolithography technique and etching technique, thereby forming a mesa 6 sandwiched between the grooves 5a and 5b. FIG. 6 is an enlarged cross-sectional view taken along line AA in FIG. The bottoms of the grooves 5a and 5b are close to the active layer 3, and the semiconductor layer 4 at the bottom of the grooves 5a and 5b has a thickness of about 1 μm, for example. For example, the width of the mesa 6 is 2 μm, and the width of the grooves 5a and 5b is 10 μm.

  Next, as shown in FIG. 7, an insulating film 7 made of SiO 2 is formed on the entire main surface side of the wafer 20. The thickness of the insulating film 7 is 0.1 to 0.3 μm.

  Next, as shown in FIG. 8, a photoresist film 21 is formed on the entire main surface side of the wafer 20. Thereafter, as shown in FIG. 9, the photomask 22 is disposed on the wafer 20 with a predetermined interval, and the photoresist film 21 is selectively exposed with light transmitted through the photomask 22.

  FIG. 10 is an enlarged plan view showing a part of the photomask 22. In FIG. 10, a portion indicated by a dotted line frame is an element formation region 23 in which one semiconductor laser element 1 is formed. As shown in FIG. 9, the element formation regions 23 are arranged vertically and horizontally.

  As shown in FIG. 10, openings 24 and 25 are provided in the photomask 22 along the center line of the element formation region 23. The opening 24 is an elongated rectangle, overlaps the mesa 6, and extends from the center of the element formation region 23 to the vicinity of the end. A plurality of openings 25 are arranged on both ends of the opening 24. In FIG. 10, the pattern is such that three openings 25 are arranged between the element formation region 23 and the element formation region 23. In the case of the semiconductor laser device 1 of FIG. 1, the number of the openings 25 is four, but the number of the openings 25 is reduced because the figure becomes complicated. When the number of non-injection portions at the end portion of the semiconductor laser element 1 is further increased, the number of openings 25 is further increased. In FIG. 10, a portion sandwiched between two two-dot chain lines is a portion where the mesa 6 is located.

  The opening 25 is disposed at a portion along the line AA in FIGS. 9 and 10. The opening 25 and the opening 24 are not provided in a portion along the line B-B, which becomes a light shielding region that does not transmit light. In the following FIG. 11 to FIG. 14, for convenience of explanation, the AA portion where the opening 25 that transmits light is present is shown on the left side, and the BB portion that is a light shielding portion that blocks light is shown on the right side.

  FIG. 11 is a cross-sectional view showing a state in which the photomask 22 is arranged on the wafer 20 with a predetermined interval and the photoresist film 21 is selectively exposed with light transmitted through the photomask 22. In the AA portion, the photoresist film 21 on the mesa 6 is exposed. The photoresist film 21 is not exposed in the BB portion.

  Next, the photoresist film 21 is developed to leave the photoresist film 21 in a structure as shown in FIG. That is, exposure and development are adjusted so that the insulating film 7 on the mesa 6 is exposed and the insulating film 7 covering the side surface of the mesa 6 is covered with the photoresist film 21 as shown in FIG. Since the photoresist film 21 is not exposed in the BB portion, the photoresist film 21 remains as it is.

  Next, as shown in FIG. 13, the insulating film 7 exposed by using the photoresist film 21 as an etching mask is removed by etching. Further, the photoresist film 21 is removed after the etching. As a result, since the insulating film 7 is covered with the photoresist film 21 in the BB portion, the insulating film 7 is not etched and remains as it is. In the AA portion, the insulating film 7 covering the upper surface of the mesa 6 is removed, and the upper surface of the mesa 6 is exposed. Further, both side surfaces of the mesa 6 are covered with the insulating film 7, and the upper surface of the semiconductor layer 4 including the grooves 5a and 5b remains without the insulating film 7 being etched.

  Next, as shown in FIG. 14, a conductor layer 9 is formed over the entire upper surface of the wafer 20, and this conductor layer 9 is patterned by a conventional photolithography technique and an etching technique. Electrode) 10, bonding pad 10c, conductor layer 9a, and mark 9b. In the AA portion of FIG. 14, since the electrode (p electrode) 10 and the mesa 6 are electrically connected, an injection portion for injecting current into the active layer 3 is formed. Further, in the BB portion of FIG. 14, since the insulating film 7 exists between the upper surface of the mesa 6 and the electrode (p electrode) 10, the insulating film 7 on the upper surface of the mesa 6 flows into the active layer 3. Insulating film 7a for current non-injection that prevents the supply of non-injection, that is, a non-injection portion.

  Next, although not shown, the lower surface of the wafer 20 is removed to a predetermined thickness to make the wafer 20 about 100 μm thick, and then an electrode (n electrode) 11 is formed over the entire lower surface of the wafer 20. Thereafter, the wafer 20 is divided vertically and horizontally to manufacture a plurality of semiconductor laser elements 1. In this division, for example, the middle of the mesa 6 and the mesa 6 is cut by a dicing blade or the like to form a strip, and then the strip is cut by cleavage to manufacture the semiconductor laser device 1. At the time of this cleavage, cleavage is performed in a direction of ± with respect to the designed cleavage line. There is no problem as long as the cleavage position deviation (variation) is small. However, if the cleavage position is greatly displaced, the conventional semiconductor laser device having the window structure has disadvantages such as generation of kinks and generation of optical loss. However, in the first embodiment, the non-implanted portion and the implanted portion are alternately arranged in the cleaving region. As a result, even when the variation in cleavage is large, the implanted portion is also present in the large length region. Since the dimensions are not increased as they are, the dimensions of the non-injection portion are not increased, but the occurrence of IL kinks due to supersaturated absorption can be suppressed. Further, it is possible to suppress the occurrence of optical loss (COD) due to the non-injection portion being too short.

  Such a semiconductor laser device 1 is incorporated in a sealed container and used as a semiconductor laser device. FIG. 15 shows a semiconductor laser device 30 incorporating the semiconductor laser element 1. The semiconductor laser device 30 includes a package main body 31 that is a main component of the assembly, and a lid 32 that is attached to the surface side of the package main body 31. The package is formed by a package body 31 and a lid body 32.

  The package body 31 is made of a circular metal plate having a thickness of several millimeters, and a copper heat sink 33 is fixed to the portion off the center of the surface with a conductive brazing material or the like. A submount 34 made of SiC (silicon carbide) is fixed to the front end side of the side surface (front surface) facing the center of the package body 31 of the heat sink 33. The submount 34 is made of a rectangular plate larger than the semiconductor laser element 1.

  Although not shown, a conductor layer is provided on the surface of the submount 34 to form a chip fixing portion and a wire connection pad extending from the chip fixing portion and having a wide tip portion. The semiconductor laser element 1 is fixed to the chip fixing part via a conductive bonding material. Therefore, the electrode (n electrode) 11 of the semiconductor laser device 1 shown in FIG. 1 is electrically connected to the wire connection pad. The wire connection pad and the heat sink 33 are electrically connected by a conductive wire 35. Thereby, the electrode (n electrode) 11 of the semiconductor laser device 1 shown in FIG. 1 is electrically connected to the package body 31.

  A light receiving element (PD) 40 that receives laser light emitted from the rear emission surface of the semiconductor laser element 1 is fixed at the center of the package body 31. The back electrode of the light receiving element 40 is connected to the package body 31 via a conductive bonding material. Accordingly, the back electrode of the light receiving element 40 is electrically equipotential with the package body 31.

  On the other hand, three leads 41 (41a, 41b, 41c) are fixed to the package body 31. The two leads 41 (41a, 41b) are fixed to the package body 41 through the insulator 42 in a penetrating manner. The remaining one lead 41 (41 c) is fixed in contact with the back surface of the package body 31 and is in an electrically equipotential state with the package body 31.

  The tip of one lead 41a protruding to the surface side of the package body 31 and the electrode 10 (bonding pad 10c: not shown in the figure) of the semiconductor laser element 1 are connected by a conductive wire 45. Further, the upper electrode of the light receiving element 40 and the tip of the other lead 41 b protruding to the surface side of the package body 31 are connected by a conductive wire 46.

  On the other hand, the lid 32 has a cap structure and has a light transmission window 50 through which the laser light 15 is transmitted. The light transmission window 50 is formed by overlapping and fixing a transparent glass plate 51 on a hole provided in the lid 32.

  In such a semiconductor laser device 30, the semiconductor laser element 1 can be operated to emit the laser beam 15 by applying a predetermined voltage between the pair of leads 41a and 41b. The laser beam 15 emitted from the front emission surface is emitted to the outside from the light transmission window 50. Further, the laser beam 15 emitted from the rear emission surface is monitored by the light receiving element 40 and the light output is monitored.

  The first embodiment has the following effects.

  (1) A region that supplies current to the pn junction that forms the resonator (injection portion) and a region that does not supply current (non-injection portion) to a constant region including the region that forms the resonator end face It is provided periodically. Therefore, when the semiconductor substrate (wafer) 20 is cleaved, even if the cleaving position varies greatly, the injection portion and the non-injection portion are alternately provided in the vicinity of the cleaved surface. There is no variation in length.

  That is, when a conventional semiconductor laser element having a window structure is formed by diffusing Zn, the variation size of the cleavage position directly increases or decreases the length of the non-injection part. Since the injection part exists between the non-injection part, the variation size of the cleavage position does not become the non-injection part length variation as it is. In particular, when there are a plurality of injection portions in the size region where the cleavage position varies, the ratio of increase / decrease of the non-injection portion to the variation in the cleavage position becomes small.

  The length of the non-injection part according to this embodiment is about 5 μm. As a result, it is possible to suppress the generation of IL kinks due to supersaturated absorption that occurs when the non-injection portion is too long as 7 μm or more. Moreover, the occurrence of optical damage (COD) can be suppressed.

  (2) In the method of manufacturing the semiconductor laser device of this embodiment, a part of the insulating film 7 is partially formed on the mesa 6 in the step of forming the insulating film 7 that covers the upper surface of the semiconductor substrate 20 except for the upper surface of the mesa 6. The non-injection portion is formed by the insulating film portion (current non-injection insulating film 7a) provided partially. Therefore, in manufacturing, it is possible to manufacture an insulating film (non-current-injecting insulating film 7a) for forming a non-injection portion only by changing a photomask for patterning the insulating film 7, and the number of processes does not increase. As a result, an increase in manufacturing cost of the semiconductor laser element 1 can be suppressed.

  16 to 18 are diagrams relating to a semiconductor laser device which is Embodiment 2 of the present invention. 16 is a schematic perspective view of the semiconductor laser device, FIG. 17 is a cross-sectional view taken along the line AA of FIG. 16, and FIG. 18 is a schematic diagram showing a planar state of the cavity end face portion of the semiconductor laser device.

  In the first embodiment, the non-injection portion is formed by periodically providing the current non-injection insulating film 7a on the upper surface of the mesa 6, but in the second embodiment, the electrode (p electrode) 10 provided on the upper surface of the mesa 6 is shown in FIG. As shown in FIGS. 16 and 17, the electrode strips 10 g for injection are periodically arranged at both end portions of the elongated mesa 6. Current is injected into the mesa 6 portion where the injection electrode band 10g exists, but the portion between the injection electrode band 10g and the injection electrode band 10g where the injection electrode band 10g does not exist and the injection electrode band 10g. And the electrode (p electrode) 10 is a non-injection part into which no current is injected.

  In the manufacture of the semiconductor laser device 1 of the first embodiment, the semiconductor laser device 1 of the second embodiment is an electrode (p) formed on the semiconductor layer 4 and overlapping the resonator without forming a non-injection portion with an insulating film. The electrode) 10 has a structure in which a portion thereof does not overlap the resonator, and a non-injection portion is formed in a portion where the electrode 10 does not overlap the resonator.

  As shown in FIG. 17, in the figure, three injection electrode bands 10g are arranged on both ends of the mesa 6, that is, on both ends of the resonator, but in reality there are more. The length of the injection electrode band 10g along the extending direction of the mesa 6 (resonator) is the same as the length of the injection portion of the first embodiment. The lengths of the non-injection part and the injection part are the same. FIG. 18 is an enlarged view of an end face portion of the semiconductor laser device 1 showing three injection electrode bands 10g formed by the electrodes (p electrodes) 10. FIG. In FIG. 18, a thin black area is a portion of the electrode 10. The electrode 10 is formed on the upper surface of the semiconductor layer 4 in a pattern as shown in FIG. In FIG. 16, a large number of injection electrode strips 10g are schematically shown so as to be divided. Since the electrode 10 is not provided between the injection electrode band 10g and the injection electrode band 10g and between the injection electrode band 10g and the electrode 10 on the mesa 6, a portion where this electrode is not provided Is no longer supplied with current, and the current density at the resonator end face can be reduced.

  In the second embodiment, similarly to the first embodiment, the non-injection portions and the injection portions are alternately and periodically arranged on the end face portion of the resonator. Even if the variation occurs, the non-injection portion does not become too long or too short, and the generation of IL kinks and the occurrence of optical damage (COD) can be suppressed.

  19 to 21 are diagrams related to a semiconductor laser device which is Embodiment 3 of the present invention. 19 is a schematic perspective view of the semiconductor laser device, FIG. 20 is a cross-sectional view taken along line AA of FIG. 19, and FIG. 21 shows a state in which a middle layer semiconductor is formed in the middle layer of the semiconductor layer in the method of manufacturing the semiconductor laser device. It is a schematic diagram shown.

  The semiconductor laser device 1 of the third embodiment has a conductivity type opposite to that of the semiconductor layer 4 in the semiconductor layer 4 without forming a non-injection portion with an insulating film in the manufacture of the semiconductor laser device 1 of the first embodiment. An intermediate layer semiconductor of the first conductivity type (n-type) is formed, and a non-injection portion is formed by the intermediate layer semiconductor portion.

  As shown in FIG. 20, an intermediate layer semiconductor 55 made of an n-type GaAs layer is provided in the middle layer of the semiconductor layer 4 periodically on the end face side of the resonator along the extending direction of the resonator. The length of the intermediate layer semiconductor 55 along the extending direction of the mesa 6 (resonator) is the same as the length of the injection portion of the first embodiment. The lengths of the non-injection part and the injection part are the same. In FIG. 20, only three intermediate layer semiconductors 55 are shown on the end face side, but in reality, the necessary number of intermediate layer semiconductors 55 are arranged for characteristic control. Since the middle layer semiconductor 55 is a non-injection portion that does not pass current, no current is supplied to the active layer 3 directly below the middle layer semiconductor 55, and the current density of the resonator end face can be reduced.

  21A and 21B are schematic cross-sectional views showing a part of the manufacture of the semiconductor laser device 1 of the third embodiment. After forming the active layer 3 on the main surface of the semiconductor substrate (wafer) 20, a first layer 57 of the second conductivity type (p-type) constituting the semiconductor layer 4 is formed on the active layer 3. . The first layer 57 is a layer made of AlGaInP.

  Next, a semiconductor layer (GaAs layer) of the first conductivity type (n-type) is formed on the main surface of the wafer 20, that is, on the first layer 57. Then, the semiconductor layer (GaAs layer) is selectively etched to form the middle layer semiconductor 58 made of the semiconductor layer (GaAs layer) on both sides of the cleavage line across the resonator. The middle-layer semiconductor 58 is formed to be elongated so as to cross the resonator, and is disposed at a predetermined interval in the extending direction of the resonator. The length and pitch of the middle layer semiconductor 58 are the same as those in the first embodiment.

  Next, a second layer 59 of the second conductivity type (p-type) constituting the semiconductor layer 4 is formed so as to cover the intermediate layer semiconductor 58 and the first layer 57. The second layer 59 is made of AlGaInP. The semiconductor layer 4 is formed by the first layer 57 and the second layer 59. The middle layer semiconductor 58 constitutes a non-injection part. No current is injected into the mesa 6 portion where the intermediate layer semiconductor 58 exists, and the current density of the resonator end face can be reduced.

  In the third embodiment, similarly to the first embodiment, the non-injection portions and the injection portions are alternately and periodically arranged at the end face portion of the resonator. Even if the variation occurs, the non-injection portion does not become too long or too short, and the generation of IL kinks and the occurrence of optical damage (COD) can be suppressed.

  22 is a schematic perspective view of a semiconductor laser device that is Embodiment 4 of the present invention, and FIG. 23 is a cross-sectional view taken along the line AA of FIG.

In the manufacture of the semiconductor laser device 1 of the first embodiment, the semiconductor laser device 1 of the fourth embodiment selectively emits protons (H ⁺ ) to the surface of the semiconductor layer 4 without forming a non-injection portion with an insulating film. The diffusion region 60 is formed by driving. The diffusion region 60 is periodically formed along the extending direction of the resonator. The diffusion region 60 is elongated so as to cross the resonator. These diffusion regions 60 form a non-injection part. The length and pitch of the diffusion region 60 are the same as those in the first embodiment.

  In the fourth embodiment, similarly to the first embodiment, the non-injection portions and the injection portions are alternately and periodically arranged on the end face portion of the resonator. Even if the variation occurs, the non-injection portion does not become too long or too short, and the generation of IL kinks and the occurrence of optical damage (COD) can be suppressed.

  24 to 26 are diagrams relating to a semiconductor laser element which is Embodiment 4 of the present invention. 24 is a schematic perspective view of the semiconductor laser device, FIG. 25 is a cross-sectional view taken along line AA of FIG. 24, and FIG. 26 is a cross-sectional view showing a cleaved portion of the wafer in the method of manufacturing the semiconductor laser device.

  The semiconductor laser device 1 of the fifth embodiment is different from the semiconductor laser device 1 of the first embodiment in that the length of the non-injection portion formed of the current non-injection insulating film 7a is partially different. That is, the length of one or more non-injection parts (current non-injection insulating film 7a) close to the end face of the resonator is the non-injection part (current non-injection part) on the back side of the resonator excluding these non-injection parts. It is shorter than the length of the insulating film 7a).

  As shown in FIG. 25, six current non-injection insulating films 7a are arranged on the left end face side of the resonator, and four current non-injection insulating films 7a are arranged on the right end face side of the resonator. ing. The difference in the number of the current non-injection insulating films 7a is due to the shift of the cleavage position. In the manufacture of the semiconductor laser device 1 of the fifth embodiment, for example, as shown in FIG. 26, the wafer (semiconductor substrate) 20 has a short current non-injection insulation having a length a at both ends of the cleavage line 61. The film 7a is arranged, and four long non-injection insulating films 7a having a length b are arranged outside the film 7a. When the cleavage is performed at the cleavage line 61, the cleavage is performed in a state where the variation from the cleavage line 61 is extremely small is the left end portion of FIG. 25. In FIG. The right end portion of FIG. 25 is obtained by cleaving in the middle of the current non-injection insulating film 7a having the dimension a next to the dimension b. The dimensions between adjacent non-current-injecting insulating films 7a are the same as in the first embodiment. For example, 2a = b. Since 2a = b, a very large temperature rise suppressing effect can be obtained while suppressing the generation of kinks.

  In the fifth embodiment, similarly to the first embodiment, the non-injection portions and the injection portions are alternately arranged on the end face portion of the resonator. Therefore, the cleavage position varies due to cleavage in the manufacture of the semiconductor laser device 1. However, the non-injection portion does not become too long or too short, and the generation of IL kinks and the occurrence of optical damage (COD) can be suppressed.

  27 to 29 are diagrams relating to a semiconductor laser element which is Embodiment 6 of the present invention. 27 is a schematic perspective view of the semiconductor laser device, FIG. 28 is a cross-sectional view taken along the line AA of FIG. 27, and FIG. 29 is a cross-sectional view showing a cavity end face portion of the semiconductor laser device. FIG. 29 is a diagram showing a left end portion of FIG.

As shown in FIG. 28, the semiconductor laser device 1 of the sixth embodiment is adjacent to the semiconductor laser device 1 of the first embodiment although the length of the non-injection portion (current non-injection insulating film 7a) is constant. The structure is such that the interval between the non-injection portions is gradually increased from the end face of the resonator toward the back.
By adopting such a structure, the temperature distribution in the resonator axial direction can be made uniform.

  In the sixth embodiment, similarly to the first embodiment, the non-injection portions and the injection portions are alternately arranged on the end face portion of the resonator, so that the cleavage position varies due to cleavage in the manufacture of the semiconductor laser device 1. However, the non-injection portion does not become too long or too short, and the generation of IL kinks and the occurrence of optical damage (COD) can be suppressed.

  Further, in the present invention, the same effect as in the sixth embodiment can be obtained even when the length of the non-injection portion is gradually increased from the end face of the resonator toward the back. Furthermore, in the present invention, the length of the non-injection part is gradually increased from the end face of the resonator toward the back, and the interval between the adjacent non-injection parts is gradually increased from the end face of the resonator to the back. Also, the same effect as in the sixth embodiment can be obtained.

  Although the invention made by the present inventor has been specifically described based on the embodiment, the present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the invention. Nor.

It is a typical perspective view of the semiconductor laser element which is Example 1 of this invention. It is sectional drawing which follows the AA line of FIG. 1, BB line, and CC line. FIG. 3 is an enlarged cross-sectional view of a resonator end surface portion of the semiconductor laser device according to the first embodiment. 3 is a schematic diagram illustrating a planar state and a cross-sectional state of a resonator end surface portion of the semiconductor laser element of Example 1. FIG. FIG. 3 is a plan view of a wafer on which mesas are formed in parallel in the method of manufacturing a semiconductor laser device according to the first embodiment. It is an expanded sectional view of the mesa part which follows the AA line of FIG. It is an expanded sectional view of the mesa part which formed the insulating film on the mesa. FIG. 4 is a partial enlarged cross-sectional view formed by overlapping a photoresist film on an insulating film on the mesa. It is a top view which shows the mask arrange | positioned on the said wafer. It is a typical enlarged plan view showing a part of the mask. FIG. 10 is a partial cross-sectional view taken along lines AA and BB in FIG. 9 in a state where the mask is disposed on the photoresist film. FIG. 10 is a partial cross-sectional view taken along lines AA and BB in FIG. 9 in a state where the photoresist film is developed. FIG. 10 is a partial cross-sectional view taken along lines AA and BB in FIG. 9 in a state where the insulating film is selectively etched using the photoresist film as a mask. FIG. 10 is a partial cross-sectional view taken along lines AA and BB in FIG. 9 in a state in which an electrode partially connected to the mesa is formed. It is the perspective view which notched a part of semiconductor laser device incorporating the semiconductor laser element of the present Example 1. FIG. It is a typical perspective view of the semiconductor laser element which is Example 2 of this invention. It is sectional drawing which follows the AA line of FIG. FIG. 6 is a schematic diagram illustrating a planar state of a resonator end surface portion of the semiconductor laser device according to the second embodiment. It is a typical perspective view of the semiconductor laser element which is Example 3 of this invention. It is sectional drawing which follows the AA line of FIG. In the manufacturing method of the semiconductor laser element which is Example 3 of this invention, it is a schematic diagram which shows the state which forms a middle layer semiconductor in the middle layer of a semiconductor layer. It is a typical perspective view of the semiconductor laser element which is Example 4 of this invention. It is sectional drawing which follows the AA line of FIG. It is a typical perspective view of the semiconductor laser element which is Example 5 of this invention. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which shows the cleavage part of the wafer in the manufacturing method of the semiconductor laser element of the present Example 5. It is a typical perspective view of the semiconductor laser element which is Example 6 of this invention. It is sectional drawing which follows the AA line of FIG. FIG. 10 is a cross-sectional view showing a resonator end face portion of a semiconductor laser device according to Example 6;

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser element, 2 ... Semiconductor substrate, 3 ... Active layer, 4 ... Semiconductor layer, 5a, 5b ... Groove, 6 ... Mesa (projection), 7 ... Insulating film, 7a ... Insulating film for non-injection of current, 9 ... Conductor layer, 9a ... Conductor layer, 9b ... Mark, 10 ... Electrode (p electrode), 10c ... Bonding pad, 11 ... Electrode (n electrode), 15 ... Laser light, 20 ... Wafer (semiconductor substrate), 21 ... Photoresist Membrane, 22 ... Photomask, 23 ... Element formation region, 24, 25 ... Opening, 30 ... Semiconductor laser device, 31 ... Package body, 32 ... Cover body, 33 ... Heat sink, 34 ... Submount, 35 ... Wire, 40 ... Light reception Element (PD) 41, 41a, 41b, 41c ... Lead, 42 ... Insulator, 45, 46 ... Wire, 50 ... Light transmission window, 51 ... Transparent glass plate, 55 ... Middle semiconductor, 57 ... First layer, 58 ... middle layer semiconductor, 9 ... second layer 60 ... diffusion region, 61 ... cleavage line.

Claims (6)

A semiconductor substrate of the first conductivity type;
An active layer provided on an upper surface of the semiconductor substrate;
A semiconductor layer of the second conductivity type formed on the active layer;
An elongated resonator formed on the semiconductor layer and formed by the semiconductor substrate, the active layer, and the semiconductor layer is provided correspondingly from end to end, and a current is supplied to the active layer portion of the resonator. An electrode for injecting,
At least one end side of the resonator includes a non-injection portion made of an insulator that prevents injection of current into the active layer and an injection portion that injects current into the active layer. Provided periodically along the direction ,
The length of the one or more non-injection portions adjacent to the end face of the resonator is shorter than the length of the non-injection portion on the back side of the resonator excluding these non-injection portions. A semiconductor laser device.   2. The semiconductor according to claim 1, wherein the length of the non-injection part is constant, and an interval between the adjacent non-injection parts gradually increases from the end face of the resonator toward the back. Laser element. Preparing a semiconductor substrate of the first conductivity type;
Forming an active layer on the upper surface of the semiconductor substrate;
Forming a semiconductor layer of the second conductivity type on the active layer;
Two grooves are formed at predetermined intervals so as to remove the semiconductor layer, and a plurality of protruding mesa sandwiched between the two grooves are formed on the active layer, and a resonator is formed under the mesa. Comprising the steps of:
Forming an insulating film covering the top surface of the semiconductor substrate except for the top surface of the mesa;
Forming an electrode selectively on the insulating film, a part of which overlaps the mesa; and
Forming an electrode on the lower surface of the semiconductor substrate;
Dividing the semiconductor substrate and each layer thereon between the mesa and the mesa, and cleaving at regular intervals in a direction orthogonal to the mesa to form a plurality of rectangular semiconductor laser elements,
Before the division and the cleavage, a non-injection portion made of an insulator that prevents injection of current into the active layer is periodically formed in the planned cleavage region where the cleavage is performed along the extending direction of the resonator. It can be provided,
The length of the one or more non-injection portions adjacent to the end face of the resonator is formed shorter than the length of the non-injection portion on the back side of the resonator excluding these non-injection portions. Manufacturing method of semiconductor laser device. The length of the non-injection part is made constant, and an interval between the adjacent non-injection parts is formed so as to be gradually widened at least in a predetermined length region from the end face of the resonator toward the back. 4. A method for producing a semiconductor laser device according to 3 . 4. The method of manufacturing a semiconductor laser device according to claim 3 , wherein the length of the non-injection portion is sequentially increased in at least a predetermined length region from the end face of the resonator toward the back. The lengths of the non-injection portions are sequentially increased in a predetermined length range from the end face of the resonator toward the back, and the interval between the adjacent non-injection portions is extended from the end face of the resonator to the back. 4. The method of manufacturing a semiconductor laser device according to claim 3 , wherein the semiconductor laser device is formed so as to gradually widen at least in a predetermined length region.

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