JP2007317804A - Semiconductor laser device, manufacturing method therefor, and semiconductor laser gyro using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor laser device in which a preferred dielectric multilayer film is provided at an end. <P>SOLUTION: This manufacturing method comprises step (i) of forming a semiconductor multilayer film 20 containing an active layer on a substrate 11; step (ii) of etching the semiconductor multilayer film 20, thereby exposing a first and second end so as to have a convex curved face toward the outside; and the step (iii) of depositing a reflective film 15 (dielectric multilayer film) on the second end 24b by a gas phase growing method. The step is carried out in such a state that the upper face side of the semiconductor multilayer film 20 is press held down by a first plate 71, the rear face side of the substrate 11 is pressed by a second plate 72, and the second end 24b is projected at a distance H (20 μm or more) from the first plate 71. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device, a manufacturing method thereof, and a semiconductor laser gyro using the same.

Conventionally, a semiconductor laser device including a resonator whose planar shape is a stadium shape is known (Patent Document 1). In this semiconductor laser device, a plurality of laser beams are emitted from an end surface having an outwardly bulging shape. When forming a mirror having a desired reflectance on the end face of the semiconductor device, the mirror is formed by laminating a dielectric layer having a predetermined thickness on the end face.
JP 2004-235339 A

  However, in the conventional method, it is difficult to form a dielectric layer having a uniform thickness on a curved surface, and thus it is difficult to form a mirror having the characteristics as designed.

  Under such circumstances, one of the objects of the present invention is to provide a method of manufacturing a semiconductor laser device having a preferable dielectric film on the end face. Another object of the present invention is to provide a semiconductor laser device having a preferable dielectric film on its end face, and a semiconductor laser gyro using the semiconductor laser device.

In order to achieve the above object, a method of the present invention for manufacturing a semiconductor laser device having first and second end faces facing each other and emitting laser light from the first end face comprises:
(I) forming a semiconductor multilayer film including an active layer on a substrate;
(Ii) exposing the first and second end faces so as to have an outwardly convex curved surface by etching the semiconductor multilayer film;
(Iii) depositing a dielectric film (A) on the second end face by a vapor deposition method. The step (iii) is a state in which the upper surface side of the semiconductor multilayer film is pressed by a first plate and the back surface side of the substrate is pressed by a second plate, and the second end surface is It is performed in a state of protruding by 20 μm or more from the first plate.

  The semiconductor laser device manufactured by the manufacturing method of the present invention is an example of the semiconductor laser device of the present invention.

  In another aspect, the semiconductor laser device of the present invention is a semiconductor laser device including a semiconductor multilayer film including an active layer, and the active layer is opposed to first and second end faces facing each other. And the first and second end surfaces are curved outwardly convex, and the first, second, third and fourth end surfaces are respectively It exists in the position of the 1st, 2nd, 3rd and 4th vertex of a virtual rhombus, and is perpendicular to the diagonal line connecting the 1st vertex and the 2nd vertex among the surfaces of the semiconductor multilayer film The entire surface existing between the virtual first plane in contact with the second vertex and the virtual second plane obtained by translating the first plane toward the first vertex by 20 μm. A dielectric film (A) is formed.

  In the semiconductor laser device of the present invention, a part of the laser beam (L1) propagating clockwise along the side of the virtual rhombus is emitted as the first laser beam from the first end face, A part of the laser beam (L2) propagating counterclockwise along the rhomboid side is emitted as the second laser beam from the first end face.

  The semiconductor laser gyro of the present invention is a semiconductor laser gyro comprising a semiconductor laser device that emits first and second laser beams and a photodetector, and the photodetector includes the first and second lasers. The semiconductor laser device according to the present invention is arranged at a position where interference fringes are formed by the laser beam, and the semiconductor laser device emits first and second laser beams.

  According to the present invention, a semiconductor laser device having a preferable dielectric film on its end face and a semiconductor laser gyro using the same can be obtained.

  Hereinafter, the present invention will be described with examples. However, the present invention is not limited to the examples described below.

[Method for Manufacturing Semiconductor Laser Device]
The method of the present invention is a method of manufacturing a semiconductor laser device that includes first and second end faces facing each other and that emits laser light from the first end face. This semiconductor laser device includes a resonator (cavity) including an active layer and optical confinement layers arranged on both sides of the active layer.

  The planar shape of the resonator includes a first region having a shape in which a rectangular short side is expanded outward. The short side portions that bulge outward are the first and second end face portions. The shape of the resonator will be described later.

  In this manufacturing method, in step (i), a semiconductor multilayer film including an active layer is formed on a substrate. The semiconductor multilayer film includes light confinement layers disposed on both sides of the active layer. The optical confinement layer includes a cladding layer having a refractive index lower than that of the active layer. There is no limitation on the structure of the active layer, and it may be a single quantum well type active layer or a multiple quantum well type active layer. Further, an active layer using quantum dots or quantum wires may be used.

  What is necessary is just to select the material which comprises an active layer according to the wavelength of the laser beam to output. For example, when emitting laser light having a wavelength longer than 1200 nm, GaInAsP formed on an InP substrate may be used. In addition, when emitting laser light having a wavelength in the range of 780 nm to 1200 nm, InGaAs / AlGaAs formed on a GaAs substrate may be used. Moreover, when emitting laser light having a wavelength in the range of 630 nm to 680 nm, AlGaInP formed on a GaAs substrate may be used. In addition, GaInN / AlGaN may be used when emitting laser light in a blue wavelength region.

  There is no limitation on the method for forming the semiconductor multilayer film, and a general method used in a method for manufacturing a semiconductor device can be applied.

  Next, by etching the semiconductor multilayer film, the first and second end faces are exposed so as to have a convex curved surface toward the outside (step (ii)). At this time, the semiconductor multilayer film is etched such that the end surface exposed by etching is substantially perpendicular to the substrate surface. By this etching, the semiconductor multilayer film is formed into a predetermined resonator shape. There is no limitation on the etching method, and a general method used in a method for manufacturing a semiconductor device can be applied.

  Next, a dielectric film (A) is deposited on the second end face by a vapor deposition method (step (iii)). This step (iii) is a state in which the upper surface side of the semiconductor multilayer film is pressed by the first plate and the back surface side of the substrate is pressed by the second plate, and the second end surface is more than the first plate. It is performed in a protruding state of 20 μm or more (for example, 25 μm or more, 30 μm or more, or 40 μm or more).

  In the manufacturing method of the present invention, after the step (ii) and before or after the step (iii), the step (a) of depositing the dielectric film (B) on the first end face by the vapor phase growth method is performed. May be. This step (a) is a state in which the upper surface side of the semiconductor multilayer film is pressed by the first plate and the back surface side of the substrate is pressed by the second plate, and the first end surface is more than the first plate. It is performed in a protruding state of 20 μm or more (for example, 25 μm or more, 30 μm or more, or 40 μm or more).

  There is no limitation on the method of forming the dielectric films (A) and (B), and a general vapor phase growth method used in a method for manufacturing a semiconductor device can be applied. This vapor deposition method may be a chemical vapor deposition method or a physical vapor deposition method. As the chemical vapor deposition method, for example, a CVD method such as a plasma CVD method or a thermal CVD method may be used. As the physical vapor deposition method, for example, a sputtering method such as an electron beam sputtering method, an ECR plasma sputtering method, or a vacuum evaporation method may be used.

  The dielectric film (A) is a reflection film or an antireflection film. The dielectric film (A) may be a dielectric multilayer film composed of a plurality of dielectric layers, or a single dielectric layer. The dielectric film (B) is a reflection film or an antireflection film. The dielectric film (B) may be a dielectric multilayer film composed of a plurality of dielectric layers, or a single dielectric layer. Both the dielectric film (A) and the dielectric film (B) may be reflective films. Further, the dielectric film (A) may be a reflection film, and the dielectric film (B) may be an antireflection film. In either case, both the dielectric film (A) and the dielectric film (B) may be a dielectric multilayer film composed of a plurality of dielectric layers, or both may be a single dielectric layer. Alternatively, one may be a dielectric multilayer film composed of a plurality of dielectric layers, and the other may be a single dielectric layer.

As the structure of the dielectric film functioning as the reflection film or the antireflection film, a known structure can be applied as the reflection film or the antireflection film. For example, a dielectric film functioning as a highly reflective film includes a high refractive index layer having a refractive index of nH and a thickness of λ / 4nH at a wavelength λ of laser light, a refractive index of nL and a thickness of λ at a wavelength λ. It may have a structure in which a plurality of low refractive index layers having a thickness of / 4 nL are alternately stacked. As the material for the high refractive index layer, for example, amorphous silicon (hereinafter sometimes referred to as “α-Si layer”) or TiO ₂ can be used. The material of the low refractive index layer, for example, can be used as _{SiO 2, Si 3 N 4,} Al 2 O 3.

  For the dielectric film functioning as an antireflection film, for example, a single layer film having a thickness of λ / 4n (n is the refractive index of the layer at the wavelength λ of the laser light) may be used. Further, as an antireflection film, a high refractive index layer (refractive index at wavelength λ: nH) and a low refractive index layer (refractive index at wavelength λ: nL), a low refractive index layer (thickness: λ / 4 nL), A dielectric multilayer film in which a high refractive index layer (thickness: λ / 2 nH) and a low refractive index layer (thickness: λ / 4 nL) are stacked in this order may be used. According to this dielectric multilayer film, an antireflection effect can be obtained over a wide wavelength band.

  The dielectric film (A) is formed in a state where the second end face is directed in the direction in which the material substance constituting the dielectric film (A) is flying. For example, when the dielectric film (A) is formed by plasma CVD, the dielectric film (A) is deposited in a state where the second end face is disposed toward the plasma region. Similarly, the dielectric film (B) is formed in a state where the first end face is directed in the direction in which the material substance constituting the dielectric film (B) is flying.

[Semiconductor laser device]
The semiconductor laser device of the present invention is a semiconductor laser device including a semiconductor multilayer film including an active layer. This semiconductor laser device is formed by the above manufacturing method.

  The active layer has first and second end faces that face each other, and third and fourth end faces that face each other. The first and second end surfaces are curved surfaces that protrude outward. The first, second, third, and fourth end faces respectively exist at the positions of the first, second, third, and fourth vertices of the virtual rhombus.

  The resonator constituted by the active layer and the optical confinement layers disposed on both sides thereof has a shape that spreads two-dimensionally. The planar shape of the resonator includes a shape in which a rectangular short side is expanded outward. The short side portion bulging outward corresponds to the first and second end faces.

  Of the surface of the semiconductor multilayer film, a virtual first plane that is perpendicular to the diagonal line connecting the first vertex and the second vertex and is in contact with the second vertex, and the first plane on the first vertex side A dielectric film (A) is formed on the entire surface existing between a virtual second plane translated by a distance H. In other words, the second surface of the surface of the semiconductor multilayer film is second than the virtual second plane that is perpendicular to the diagonal line connecting the first vertex and the second vertex and is separated from the second vertex by the distance H. A dielectric film (A) is formed on the entire surface existing on the apex side.

  The distance H is at least 20 μm, for example, 25 μm, 30 μm, or 40 μm. The upper limit of the distance H is not particularly limited, but may be set to 1/10 or less of the resonator length (distance L) in consideration of ease of manufacture and heat dissipation. For example, when the distance L is 600 μm, the distance H may be 60 μm or less. The dielectric film (A) may be formed in a region other than the region between the first plane and the second plane.

  In the semiconductor laser device of the present invention, a virtual third plane perpendicular to the diagonal line connecting the first vertex and the second vertex of the surface of the semiconductor multilayer film and in contact with the first vertex; The dielectric film (B) may be formed on the entire surface existing between the second plane and the virtual fourth plane that is translated by the distance H ′ to the second vertex side. In other words, out of the surface of the semiconductor multilayer film, it is perpendicular to the diagonal line connecting the first vertex and the second vertex and is away from the virtual fourth plane separated by the distance H ′ from the first vertex. A dielectric film (A) is formed on the entire surface existing on the apex side of 1.

  The distance H ′ is at least 20 μm, for example, 25 μm, 30 μm, or 40 μm. The upper limit of the distance H ′ is not particularly limited, but may be set to 1/10 or less of the resonator length (distance L) in consideration of ease of manufacture and heat dissipation. For example, when the distance L is 600 μm, the distance H ′ may be 60 μm or less. The dielectric film (B) may be formed in a region other than the region between the third plane and the fourth plane. Since the dielectric film (A) and the dielectric film (B) have been described above, redundant description will be omitted.

  In the semiconductor laser device of the present invention, a part of the laser light (L1) propagating clockwise along the side of the virtual rhombus is emitted as the first laser light from the first end face, A part of the laser beam (L2) propagating counterclockwise along the side may be emitted as the second laser beam from the first end face. In this case, the electrodes are formed so that current can be injected intensively at positions corresponding to the side portions of the virtual rhombus. Specifically, the electrode formed on the semiconductor multilayer film is in contact with the semiconductor multilayer film in a contact region having a shape corresponding to a virtual rhombus side. This contact region covers 50% or more (preferably 70% or more, more preferably 90% or more) of the side of the virtual rhombus when it is projected in the film thickness direction.

[Semiconductor laser gyro]
The semiconductor laser gyro of the present invention includes a semiconductor laser device that emits first and second laser beams and a photodetector. The photodetector is arranged at a position where an interference fringe is formed by the first and second laser beams. The semiconductor laser device is the above-described semiconductor laser device of the present invention that emits first and second laser beams. The photodetector preferably includes a plurality of photodetector elements. There is no particular limitation on the light detection element, and for example, a photodiode or a phototransistor can be used.

  The semiconductor laser gyro of the present invention is a gyro in which the semiconductor laser device of the present invention is applied to a semiconductor laser device, for example, in the semiconductor laser gyro described in the pamphlet of International Publication No. WO2005 / 085759.

[Example of semiconductor laser device]
Hereinafter, an example of the semiconductor laser device and the manufacturing method thereof according to the present invention will be described. A perspective view of an example of a semiconductor laser is shown in FIG. 1, and a sectional view taken along line II-II in FIG. 1 is shown in FIG. Note that the drawings used for explaining the present invention are schematic, and the scale of each part is changed for easy understanding.

  A semiconductor laser device 100 shown in the perspective view of FIG. 1 includes a substrate 11, a semiconductor multilayer film 20 formed on the substrate 11, an insulating layer 12 and a first electrode 13 formed on the semiconductor multilayer film 20, A second electrode 14 formed on the entire back surface side of the substrate 11, and reflection films (high reflection films) 15 and 16 formed so as to cover a part of the semiconductor multilayer film 20 are provided. In order to facilitate understanding, FIG. 3 shows a perspective view when it is assumed that the reflection films 15 and 16 have been removed.

  Referring to FIG. 2, the semiconductor multilayer film 20 includes a buffer layer 21, a cladding layer 22, an SCH layer 23, an active layer 24, an SCH layer 25, a cladding layer 26, and a cap layer 27 that are sequentially stacked from the substrate 11 side. Including. On the cap layer 27, the patterned insulating layer 12 is formed. A first electrode 13 is formed on the insulating layer 12. Since the insulating layer 12 has a through hole, the first electrode 13 and the cap layer 27 are in contact with each other in the contact region 31 through the through hole.

  4 and 5 show planar shapes when the active layer 24 of the semiconductor laser device 100 is viewed from above. In FIG. 5, the portion of the contact region 31 where the first electrode 13 and the semiconductor multilayer film 20 (cap layer 27) are in contact is indicated by hatching. Each layer constituting the semiconductor multilayer film 20 has the same planar shape as that of the active layer 24. For example, the planar shapes of the layers constituting the cavity (the active layer 24, the SCH layers 23 and 25, and the cladding layers 22 and 26) are the same.

  Referring to FIG. 4, the active layer 24 is a thin film formed in a planar shape including a virtual rhombic path 32. Among the first to fourth vertices 32a to 32d of the path 32, the inner angles at the first and second vertices 32a and 32b are smaller than the inner angles at the third and fourth vertices 32c and 32d. The active layer 24 has first to fourth end faces 24a to 24d arranged to include the vertices 32a to 32d. The first and second end faces 24a and 24b are curved surfaces that protrude outward. The third and fourth end faces 24c and 24d are flat planes.

  The active layer 24 includes a first region 24f and four second regions 24s adjacent to the first region 24f. The planar shape of the first region 24f is a shape in which a rectangular short side is expanded outward. The path 32 is formed in the first region 24f. The active layer 24 constituted by the first region 24f and the second region 24s has a substantially H-shape (more specifically, a shape obtained by horizontally extending the H-shape).

  Referring to FIG. 5, contact region 31 in which first electrode 13 and cap layer 27 are in contact is formed in a substantially rhombus side shape so as to correspond to path 32. The reason why the contact region 31 does not completely correspond to the path 32 is that when the through hole is formed in the insulating layer 12, there is a limitation in the manufacturing process. Although it is possible to form the contact region 31 in a diamond shape by a known method so as to completely correspond to the path 32, the manufacturing process becomes complicated.

  When a voltage is applied between the first electrode 13 and the second electrode 14 to inject carriers into the active layer 24, light is emitted from the active layer 24. This light is distributed in the active layer 24 and its vicinity by the optical confinement layers (cladding layers 22 and 26, SCH layers 23 and 25), a part is emitted to the outside of the laser as a spontaneous emission light, and a part is a specific part Guided emission occurs while being guided through the path and being reflected by a specific end face. That is, the light propagating on the path 32 causes stimulated emission while being reflected by the end faces 24a to 24d. For this reason, laser light (L1) propagating clockwise through the path 32 is generated. Similarly, laser light (L2) propagating counterclockwise through the path 32 is generated. A part of the laser beams (L1) and (L2) is emitted from the first vertex 32a of the first end face 24a to become the first and second laser beams 35 and 36 (see FIG. 5).

  As shown in FIG. 1, reflection films 15 and 16 (dielectric multilayer films) are formed on the first and second end faces 24a and 24b. The distance L (see FIG. 4) between the first vertex 32a and the second vertex 32b is 600 μm, and the distance W between the third vertex 32c and the fourth vertex 32d is 60 μm. In the semiconductor laser device 100, the laser beams (L1) and (L2) are totally reflected at the end faces 24c and 24d.

  The four second regions 24s are formed in order to suppress a mode generated by the multiple reflection of the laser light generated in the first region 24f on the end surfaces 24c and 24d. In the semiconductor laser device 100, the length Ls (see FIG. 4) of the second region 24s in the direction parallel to the diagonal line 32ab connecting the first vertex 32a and the second vertex 32b is 160 μm. L / 4 is 150 μm, and L / 4 <Ls is satisfied. The above mode is particularly suppressed when L / 4 <Ls is satisfied. The length Ws of the second region 24s in the direction of the diagonal line 32cd connecting the third vertex 32c and the fourth vertex 32d is 70 μm.

  The shapes of the end faces 24a and 24b are each a partial shape of a cylindrical curved surface. Specifically, it has the same shape as a part of a curved surface of a cylinder on the diagonal line 32ab and having a central axis perpendicular to the surface of the active layer 24. The radius of the cylinder, that is, the curvature radius R1 (see FIG. 3) of the end face 24a is 600 μm, and the curvature radius R2 (not shown) of the end face 24b is also 600 μm. However, the curvature radii R1 and R2 may not be equal to the distance L, and may be a value selected from a range of 0.5 to 2 times the distance L (for example, 300 μm). The end surface 24a in the vicinity of the apex 32a has the above-described radius of curvature, but the radius of curvature may be changed (for example, may be smaller) in the second region 24s. Similarly, the end surface 24b in the vicinity of the vertex 32b has the above-described radius of curvature, but the radius of curvature may be changed (for example, may be smaller) in the second region 24s.

  The planar shape of the semiconductor laser device 100 is symmetrical with respect to the diagonal line 32ab and the diagonal line 32cd, and the planar shape of the end face 24b is with respect to the diagonal line 32cd connecting the third vertex 32c and the fourth vertex 32d. It is a shape symmetrical with the planar shape of the end surface 24a. However, the planar shape of the semiconductor laser of the present invention is not necessarily a line-symmetric shape. For example, the end surface 24b may be a curved surface having a different curvature from the end surface 24a.

  Table 1 shows the materials and film thicknesses of the substrate 11 and the semiconductor multilayer film 20. Table 1 also shows the dopant concentration of some of the semiconductor layers.

The active layer 24 has a well layer (GaAs layer, thickness: about 6 nm) and a barrier layer (Al _0.2 Ga _0.8 As layer, thickness: about 9 nm), which are barrier layer / well layer / barrier layer / well layer / barrier. It has a structure in which layers / well layers / barrier layers are stacked in this order.

As the insulating layer 12, a Si ₃ N ₄ layer (thickness: about 200 nm) is used. A Ti / Pt / Au layer (thickness: about 270 nm) is used for the first electrode 13. A Ge / Ni / Au layer (thickness: about 240 nm) is used for the second electrode 14.

  The buffer layer 21 is formed in order to obtain a high-quality III-V group compound semiconductor crystal. The SCH layers 23 and 25 are layers for performing efficient current injection into the active layer 24 and for distributing light in the vicinity of the active layer together with the cladding layers 22 and 26.

  The cladding layers 22 and 26 and the SCH layers 23 and 25 are made of a material having a refractive index lower than that of the active layer 24. Since the refractive index of the active layer 24 is the highest, the light generated in the active layer 24 is confined to the active layer 24 and its vicinity by the SCH layers 23 and 25 and the cladding layers 22 and 26.

  The first electrode 13 of the semiconductor laser device 100 may include a first portion that injects a current that generates a gain, and a second portion that injects a smaller current than the first portion.

  The reflective film 15 is at least a virtual first plane that is perpendicular to the diagonal line connecting the first vertex 32a and the second vertex 32b and is in contact with the second vertex 32b, of the surface of the semiconductor multilayer film 20. The first plane is formed on the entire surface existing between the first plane 32a and the virtual second plane which is translated by 20 μm toward the first vertex 32a. The reflective film 16 is at least a virtual third plane that is perpendicular to the diagonal line connecting the first vertex 32a and the second vertex 32b and is in contact with the first vertex 32a of the surface of the semiconductor multilayer film 20. And a virtual fourth plane obtained by translating the third plane by 20 μm toward the second vertex 32b.

Each of the reflection films 15 and 16 has a laminated structure of SiO ₂ layer / α-Si layer / SiO ₂ layer / α-Si layer / SiO ₂ layer. The thickness of one SiO ₂ layer and the thickness of one α-Si layer (amorphous silicon layer) are both set to be λ / 4n at the vertex 32a (or vertex 32b). Here, λ is the wavelength of the laser beam and is about 850 nm. N is the refractive index of each layer at the wavelength λ. Specifically, the thickness of one SiO ₂ layer is about 144 nm, and the thickness of one α-Si layer is about 55 nm.

[Example of Manufacturing Method of Semiconductor Laser Device]
Hereinafter, an example of the method of the present invention for manufacturing the semiconductor laser device 100 will be described.

  6A to 6H schematically show the manufacturing process. 6A to 6H, the surface of the insulating layer 12 is hatched to facilitate understanding of the formation state of the insulating layer 12. 6 is performed on the wafer, FIG. 6 shows only a part of the enlarged view.

First, as shown in FIG. 6A, a semiconductor multilayer film 20a composed of a plurality of semiconductor layers and an insulating layer 12a having a thickness of, for example, 0.4 μm are formed on a substrate 11. The semiconductor multilayer film 20a is a layer that becomes the semiconductor multilayer film 20 (see FIG. 2) by etching. Each layer constituting the semiconductor multilayer film 20a can be formed by a general method, for example, MBE (Molecular Beam Epitaxy) method or MOCVD (Metal Organic Chemical Vapor Deposition) method. The insulating layer 12a is made of, for example, Si ₃ N ₄ or SiO ₂ . The insulating layer 12a can be formed by a method such as sputtering or CVD.

  Next, as shown in FIG. 6B, a patterned resist film 201 is formed on the insulating layer 12a. The resist film 201 is patterned into the shape of the active layer 24 shown in FIG.

  Next, after the insulating layer 12a is etched using the resist film 201 as a mask, the resist film 201 is removed. Next, using the insulating layer 12 (patterned insulating layer 12a) as a mask, the semiconductor multilayer film 20a and a part of the substrate 11 are etched (FIG. 6C). Etching is performed by RIE (Reactive Ion Etching), and etching is performed until at least the buffer layer 21 or the substrate 11 is reached. The insulating layer 12 and the semiconductor multilayer film 20 having a predetermined shape are formed by etching. Etching is performed under conditions such that the verticality and smoothness of the side surfaces of the semiconductor multilayer film 20 are enhanced. Such conditions are commonly employed in semiconductor manufacturing processes. By etching, the planar shape of all the semiconductor layers constituting the semiconductor multilayer film 20 becomes the same as the planar shape of the active layer 24 shown in FIG. Further, the side surface of the semiconductor multilayer film 20 becomes a mirror surface.

  Next, as shown in FIG. 6 (d), two through holes 12 h arranged in a substantially diamond shape are formed in the insulating layer 12 so as to correspond to the contact region 31 (see FIGS. 2 and 5). The through hole 12h can be formed by a general photolithography / etching process.

  Next, as illustrated in FIG. 6E, a resist film 202 is formed so as to cover the entire surface of the substrate 11. At this time, in order to fill a step between the surface of the substrate 11 and the surface of the insulating layer 12, the resist film 202 is preferably composed of two layers, a resist layer 202a and a resist layer 202b. The resist film 202 can be formed by applying the resist layer 202b after applying the resist layer 202a to the entire surface of the substrate 11 to fill the steps. According to this method, the resist film 202 with high surface flatness can be formed.

  Next, as shown in FIG. 6F, the resist film 202 is patterned to form a through hole 202 h in the resist film 202. The through hole 202h is formed in a shape corresponding to a region where the first electrode 13 is formed. After forming the through hole 202h, the semiconductor multilayer film 20 (cap layer 27) in the through hole 202h is obtained so that a good contact can be obtained between the semiconductor multilayer film 20 (cap layer 27) and the first electrode 13. The surface of is etched about 0.01 μm to 0.02 μm.

  Next, as shown in FIG. 6G, the first electrode 13 is formed. The first electrode 13 can be formed by a lift-off method. Specifically, first, a metal layer constituting the first electrode 13 is formed by an evaporation method such as an electron beam evaporation method so as to cover the resist film 202. Thereafter, the resist film 202 is removed with acetone. In this way, the first electrode 13 having a predetermined shape can be formed. The first electrode 13 is in contact with the semiconductor multilayer film 20 (cap layer 27) through the through hole 12h formed in the insulating layer 12.

  Next, as shown in FIG. 6H, the second electrode 14 is formed on the back surface of the substrate 11. The second electrode 14 is also formed by an evaporation method such as an electron beam evaporation method.

  The following steps will be described with reference to FIG. In FIG. 7, the insulating layer 12 and the first and second electrodes 13 and 14 are not shown. On the substrate 11 (wafer), as shown in the top view of FIG. 7A, a plurality of semiconductor multilayer films 20 are formed in a matrix. The substrate 11 is cleaved so that the plurality of semiconductor multilayer films 20 are separated in a bar shape for each of a plurality of elements arranged in a row (see a top view in FIG. 7B).

  Next, as shown in the perspective view of FIG. 7C, the rear surface side (surface of the second electrode 14) of the separated substrate 11 and the upper surface side of the semiconductor multilayer film 20 (surface of the first electrode 13). Are sandwiched between a jig 70 including a first plate 71 and a second plate 72 and set in a plasma CVD apparatus. The upper surface side of the semiconductor multilayer film 20 is pressed by the first plate 71, and the back surface side of the substrate 11 is pressed by the second plate 72. At this time, as shown in FIG. 7 (d), the substrate 11 and the semiconductor multilayer film 20 are formed so that the end face 24b (vertex 32b) protrudes from the end of the first plate 71 by a distance H (20 μm or more). The jig 70 is sandwiched. Normally, the end surface 24b side protrudes from the end of the second plate 72 by a distance H (20 μm or more). However, as long as the semiconductor laser device of the present invention can be formed, the apex 32b and the end of the second plate 72 are provided. May be less than the distance H.

The jig 70 is set in the plasma CVD apparatus so that the end surface 24b faces the plasma region. Then, in this state, thereby laminating the SiO ₂ layer and the alpha-Si layer constituting the reflection layer 15 in this order. A dielectric multilayer film (reflection film 15) is formed in a region exposed from the jig 70 in the region on the end face 24b side.

  On the back surface side of the substrate 11 (the surface of the second electrode 14) and the upper surface side of the semiconductor multilayer film 20 (the surface of the first electrode 13), only the portions protruding from the first and second plates 71 and 72 are used. A dielectric multilayer film is formed. On the other hand, in other regions, the dielectric multilayer film is formed not only in the range of the distance H from the end surface 24b to the end surface 24a but also in the region closer to the end surface 24a. In any case, the reflective film 15 is a virtual first of the surfaces of the semiconductor multilayer film 20 that is perpendicular to the diagonal line connecting the first vertex 32a and the second vertex 32b and is in contact with the second vertex 32b. And a virtual second plane obtained by translating the first plane toward the first vertex 32a by a distance H (20 μm or more). According to this forming method, the thickness uniformity of the reflective film 16 on the end face 24b can be increased, and a semiconductor laser device having excellent characteristics such as a reduction in threshold current can be obtained.

  Next, the substrate 11 on which the reflective film 15 is formed is reset on the jig 70. The upper surface side of the semiconductor multilayer film 20 is pressed by the first plate 71, and the back surface side of the substrate 11 is pressed by the second plate 72. At this time, the substrate 11 and the semiconductor multilayer film 20 are sandwiched by the jig 70 so that the end face 24 a side protrudes from the end of the first plate 71 by a distance H ′ (20 μm or more). Normally, the end surface 24a side protrudes from the end of the second plate 72 by a distance H ′ (20 μm or more), but as long as the semiconductor laser device of the present invention can be formed, the apex 32a and the end of the second plate 72 The distance to the part may be less than the distance H ′.

The jig 70 is set in the plasma CVD apparatus so that the end surface 24a faces the plasma region. Then, in this state, the SiO ₂ layer and the α-Si layer that constitute the reflective film 16 are sequentially laminated. In regions exposed from the first and second plates 71 and 72, a dielectric multilayer film (reflection film 16) is formed. Similar to the reflective film 15, the reflective film 16 is formed in a predetermined region. That is, the reflective film 16 includes a virtual third plane that is perpendicular to the diagonal line connecting the first vertex 32a and the second vertex 32b and is in contact with the first vertex 32a on the surface of the semiconductor multilayer film 20. The third plane is formed on the entire surface existing between the third plane and the virtual fourth plane that is translated by a distance H ′ (20 μm or more) toward the second vertex 32b. According to this formation method, the uniformity of the thickness of the reflective film 16 on the end face 24a can be increased, and a semiconductor laser device having excellent characteristics such as a reduction in threshold current can be obtained. In the laser device according to the present invention, the dielectric multilayer film is deposited with good uniformity on the light emitting end face of the laser device constituting the laser bar. Therefore, according to the present invention, a laser device with uniform characteristics can be realized with a high yield, and a low-cost semiconductor laser device can be realized.

  Next, the substrate 11 is separated for each element. In this way, a semiconductor laser device is formed. In order to facilitate cleavage of the substrate 11, a step of thinning the substrate 11 may be performed during or after the above-described steps. Moreover, when alloying the metal layer which comprises the 1st electrode 13 and the 2nd electrode 14, after vapor-depositing a metal layer, you may heat-process at 400-450 degreeC.

A semiconductor laser device 100 having a ring electrode (ring-shaped contact region), the change in the threshold current I _th in the case of changing the distance H and H 'were determined. The result is shown in FIG. In addition, a semiconductor laser device having a stripe electrode (the contact region 31 has a stripe shape) was fabricated and subjected to the same evaluation. In addition, for a Fabry-Perot type semiconductor laser device (reference example) in which the end surface from which laser light is emitted is a flat surface, reflection films (reflectance: 95%) are formed on both end surfaces in the same manner as the semiconductor laser device 100. The same evaluation was performed. These evaluation results are also shown in FIG. The reflection films of the three semiconductor laser devices were formed using PD-2400L manufactured by Samco.

  The distance on the horizontal axis in FIG. 8 indicates the smaller one of the distance H and the distance H ′. The vertical axis in FIG. 8 is a value when the threshold current when the reflective film is not formed on the end face is 100%. In the semiconductor laser device of the reference example, since the end surface is flat, the reflective film is formed with good uniformity. Therefore, in the semiconductor laser device of this reference example, the threshold current is ideally reduced by forming the reflective film.

  As shown in FIG. 8, even in the semiconductor laser device having a curved end face, the threshold current can be lowered when the distance H and the distance H ′ are 20 μm or more (preferably 30 μm or more, more preferably 40 μm or more). .

  FIG. 9A shows the shape of the contact region 31 of the semiconductor laser device 100 whose evaluation results are shown in FIG. In FIG. 9A, S1 = 590 μm, S2 = 550 μm, S3 = 150 μm, S4 = 50 μm, T1 = 50 μm, and T2 = 6 μm. FIG. 9B shows the shape of the contact region 31 of the semiconductor laser device having the striped contact region whose evaluation results are shown in FIG. The length of the contact region 31 in FIG. 9B is 580 μm and the width is 46 μm. The semiconductor laser device having the contact region shown in FIG. 9B emits laser light in a direction along the diagonal line 32ab.

  In the semiconductor laser device of the present invention, the shape of the contact region 31 may be a combination of a ring-shaped contact region and a stripe-shaped contact region as shown in FIG.

[Example of semiconductor laser gyro]
The configuration of an example of the semiconductor laser gyro according to the present invention is schematically shown in FIG. A gyro 110 shown in FIG. 10 includes the semiconductor laser device 100 shown in FIG. 1, a photodetector 116, and a prism 117. The photodetector 116 includes two light receiving elements 116a and 116b.

  The optical paths of the two laser beams in the gyro 110 are schematically shown in FIG. The two laser beams emitted from the semiconductor laser device 100 are overlapped by the prism 117 to generate interference fringes. The movement of the interference fringes is observed by the two light receiving elements 116 a and 116 b of the photodetector 116. The interference fringes move in the direction of the arrow at a speed corresponding to the rotational speed of the gyro 110. The movement direction of the interference fringes changes corresponding to the rotation direction of the gyro 110. By detecting the moving direction and moving speed of the interference fringes, the rotating direction and rotating speed of the gyro 110 can be calculated. Note that the shape of the prism 117 is determined according to conditions such as the angle and interval between the two incident laser beams and the distance from the photodetector 116.

  Although FIG. 10 shows an example of a gyro that causes two laser beams emitted from the semiconductor laser device 100 to interfere with each other using a prism, a lens or the like may be used instead of the prism. The semiconductor laser gyro may include a Peltier element.

  The present invention can be applied to a semiconductor laser device, a manufacturing method thereof, and a semiconductor laser gyro using the same.

It is a perspective view which shows typically an example of the semiconductor laser apparatus of this invention. It is sectional drawing of the semiconductor laser apparatus shown in FIG. FIG. 2 is a perspective view of the semiconductor laser device shown in FIG. 1 when it is assumed that a reflective film has been removed. It is a figure which shows the planar shape of the active layer of the semiconductor laser apparatus shown in FIG. FIG. 5 is a diagram schematically showing a positional relationship between a planar shape of the active layer shown in FIG. 4 and a current injection region. FIG. 3 is a process perspective view illustrating an example of a method for manufacturing the semiconductor laser device illustrated in FIG. 1. FIG. 7 is a diagram illustrating a process subsequent to FIG. 6. It is a graph which shows the relationship between the magnitude | size of the area | region in which a reflecting film is formed, and threshold current. It is a top view which shows the example of the shape of a contact area | region about the semiconductor laser apparatus of this invention. It is a figure which shows typically the structure and function of an example about the semiconductor laser gyro of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Semiconductor laser apparatus 11 Substrate 12 Insulating layer 13 1st electrode 14 2nd electrode 15, 16 Reflective film (dielectric multilayer film)
20 Semiconductor multilayer film 21 Buffer layer 22, 26 Clad layer 23, 25 SCH layer 24 Active layer 24a, 24b, 24c, 24d End face 24f First region 24s Second region 31 Contact region 32 Rhombus path 32a, 32b, 32c , 32d Vertex 35, 36, L1, L2 Laser light 70 Jig 71 First plate 72 Second plate 110 Semiconductor laser gyro 116 Light receiving element 116a, 116b Light receiving element 117 Prism

Claims (7)

A method of manufacturing a semiconductor laser device comprising first and second end faces facing each other and emitting laser light from the first end face,
(I) forming a semiconductor multilayer film including an active layer on a substrate;
(Ii) exposing the first and second end faces so as to have an outwardly convex curved surface by etching the semiconductor multilayer film;
(Iii) depositing a dielectric film (A) on the second end face by a vapor deposition method,
The step (iii) is a state in which the upper surface side of the semiconductor multilayer film is pressed by a first plate and the back surface side of the substrate is pressed by a second plate, and the second end surface is the first plate. 2. A method for manufacturing a semiconductor laser device, wherein the semiconductor laser device is protruded by 20 μm or more from one plate.   The vapor deposition method performed in the step (iii) is a plasma CVD method, and the dielectric film (A) is deposited in a state where the second end face is disposed toward a plasma region. 2. The production method according to 1. After the step (ii), before or after the step (iii), further comprising: (a) depositing a dielectric film (B) on the first end face by vapor phase epitaxy;
The step (a) is a state in which the upper surface side of the semiconductor multilayer film is pressed by a first plate and the back surface side of the substrate is pressed by a second plate, and the first end surface is the first plate. The manufacturing method of Claim 1 or 2 performed in the state which protruded 20 micrometers or more rather than 1 board.   The manufacturing method according to claim 3, wherein both the dielectric film (A) and the dielectric film (B) are reflection films.   The manufacturing method according to claim 4, wherein both the dielectric film (A) and the dielectric film (B) are dielectric multilayer films comprising a plurality of dielectric layers.   A semiconductor laser device manufactured by the manufacturing method according to claim 1. A semiconductor laser gyro comprising a semiconductor laser device that emits first and second laser beams and a photodetector,
The photodetector is disposed at a position where an interference fringe is formed by the first and second laser beams;
A semiconductor laser gyro, wherein the semiconductor laser device is the semiconductor laser device according to claim 6.

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