JP2005109310A - Semiconductor laser equipment, manufacturing method of the same, and optical pickup system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide semiconductor laser equipment where a plurality os semiconductor lasers can be precisely and densely arranged on one substrate, by preventing the emitting optical axes of respective semiconductor lasers from separating from each other in the semiconductor laser equipment, where the two or more semiconductor lasers are integrated. <P>SOLUTION: At a laminated substrate 1, consisting of silicone (100) substrates 2a to 2c laminated so as to make their surfaces respectively parallel in a state of sandwiching SiO<SB>2</SB>layers 3a and 3b, rectangular grooves 5 and 6 are formed by using anisotropic wet etching. The groove 5 and the groove 6, respectively reach the SiO<SB>2</SB>layer 3a and the SiO<SB>2</SB>layer 3b. On the bottom surfaces of the grooves 5 and 6, the semiconductor lasers 8 and 9 are placed. On their side faces, micro-mirrors which reflect laser beams emitted from the semiconductor lasers to guide over the substrat 1 are formed. In a side surface, including an area which is irradiated with the laser beams in the groove 6, the side face within the substrate 2a has the shape of a cross section, folded back at the middle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser device in which two or more semiconductor lasers are integrated, and more particularly to a semiconductor laser device used in an optical pickup device that emits light of two different wavelengths and a method for manufacturing the same.

  A conventional example of a semiconductor laser device used in an optical pickup device is disclosed in Patent Document 1, for example. FIG. 7 is a sectional view of a conventional semiconductor laser device. A rectangular groove is formed in a silicon (100) substrate 61 whose principal axis of the substrate is inclined by using an anisotropic wet etching technique, and a semiconductor laser 62 is placed on the bottom of the groove. In this case, the (111) plane and the crystal plane with the same index are exposed on the four groove side surfaces. In the silicon crystal, the (100) plane and the (111) plane do not form an angle of 45 °. Therefore, by using a substrate whose crystal principal axis is inclined as the substrate 61, one of the groove side surfaces can be accurately set with respect to the substrate surface. A surface having an angle of 45 ° can be formed. By providing a micromirror 63 on this side surface and making the micromirror 63 and the emission end face of the semiconductor laser 62 face each other, the emitted light of the semiconductor laser can be accurately emitted in a direction of 90 ° with respect to the substrate surface. Is possible.

  However, in recent years, there has been a strong demand for recording / reproducing different types of optical disks such as CDs and DVDs with one optical disk drive. In this case, it is highly necessary that the optical pickup device is also a single device, and a technique for integrating light sources having different wavelengths has attracted attention.

As a conventional example in which two semiconductor lasers are integrated, for example, a configuration shown in Patent Document 2 has been proposed. FIG. 8 is a diagram showing the configuration of an integrated semiconductor laser device in the prior art. On the substrate 71, two semiconductor lasers 72 and 73 having different wavelengths are arranged so that their light emitting points face each other, and a mirror 74 is provided between the semiconductor lasers 72 and 73. The light emitted from the semiconductor laser 72 is reflected upward by the mirror surface 74a. The light emitted from the semiconductor laser 73 is reflected upward by the mirror surface 74b. This makes it possible to manufacture a light emitting device having two light sources mounted in a space similar to the case where one light source is disposed, and by making the emission end faces of the two semiconductor lasers face each other, an optical disk (not shown). 3), it is possible to reduce the optical axis shift amount of the light emitted from each semiconductor laser, and to make the apparent optical axis substantially the same. Furthermore, when considering an optical system incorporating a light emitting device of this structure, the optical axis of the emitted light is the same, so it is possible to share various optical axis components and omit optical axis correction components. The number of points can be reduced and the space can be saved.
JP-A-5-327131 JP 2002-123961 A

  However, the above-described integrated semiconductor laser device has the following problems.

  The first problem is that the mirror mounting tolerance directly affects the shake of the outgoing optical axis. In the conventional technique disclosed in Patent Document 1, the relative position between the substrate and the mirror is uniquely determined by the crystal axis direction of the substrate, and is very accurate. However, in the case of the mirror mounting type as described above, the mirror position and angle within the substrate surface change depending on the mounting accuracy. In particular, with respect to the x- and y-axis directions shown in FIG. 8, in particular, the shift and rotation in the x-direction greatly affect the shake of the optical axis. When the mirror rotates, the difference in inclination in the y direction of each optical axis is twice the mirror rotation angle. Further, the z-axis mounting position causes the optical axis tilt in the x direction due to the processing accuracy of the mirror itself, particularly the flatness and the angle formed by each mirror surface.

  The second problem is that there is a limit in reducing the distance between the optical axes of the two light sources. In the prior art shown in Patent Document 1, the mirror height is about 50 to 60 μm. This is the minimum necessary size to secure the necessary light amount, that is, the necessary radiation angle derived from the intensity distribution of the emitted light of the laser. When this is replaced as an external component, assuming that the angle between the mirror surfaces 74a and 74b and the bottom surface is 45 °, the dimension in the x direction of the mirror bottom surface portion is 100 to 120 μm. However, even if the distance between the two optical axes is about 100 μm apart, it can be a big problem. On the other hand, it is difficult to greatly reduce the size of the external parts.

  Accordingly, an object of the present invention is to provide a simple manufacturing method capable of bringing the optical axis interval close to each other in a semiconductor laser device in which two light sources are integrated.

In order to solve the above-described problems, the semiconductor laser device of the present invention is configured so that a plurality of substrates are parallel to each other with an intermediate layer made of a material different from the substrate interposed between the plurality of substrates. A plurality of rectangular grooves having a rectangular shape in plan view are provided on the surface of the laminated substrate,
Among the plurality of rectangular grooves, at least a pair of adjacent rectangular grooves are arranged such that the ridge lines of the openings are parallel to each other, and one is in the first substrate on the outermost surface and the other is in the outermost surface. It is formed so as to reach a second substrate located immediately below the substrate on the surface, and one or more semiconductor lasers are placed on the bottom of each rectangular groove, and the side surface of the rectangular groove is The region irradiated with the laser beam emitted from the semiconductor laser mounted on the bottom of the rectangular groove is formed at an angle of 40 ° to 50 ° with respect to the surface of the laminated substrate, and the laser Micro-mirrors that reflect the irradiated laser beam and guide it to the upper side of the laminated substrate are formed in the region irradiated with light, and the pair of rectangular grooves hit the laser beam on the side surface of each rectangular groove When each area is viewed in plan Among the side surfaces including the region irradiated with the laser beam in the other rectangular groove that is disposed at a position facing each other and reaches the second substrate, the side surface is folded halfway in the substrate at the outermost surface. It is characterized by having a cross-sectional shape.

  Preferably, the bottoms of the plurality of rectangular grooves are each formed by an intermediate layer surface exposed by reaching a boundary surface between the substrate and the intermediate layer in the depth direction.

  The bottoms of the plurality of rectangular grooves may be formed by substrate surfaces that are exposed by reaching the boundary surface between the intermediate layer and the substrate in the depth direction.

  The intermediate layer and the substrate are preferably made of materials having different etching rates for the acidic solution and the alkaline solution.

  The plurality of substrates are silicon (100) substrates having a <110> direction in a plane and a surface having a (100) plane tilted in a range of 5 to 15 degrees with the <110> direction as a rotation axis. It is preferable.

  Since at least one of the plurality of rectangular grooves reaches a substrate different from the other rectangular grooves, the semiconductor lasers mounted in the rectangular grooves having different depths from the surface of the laminated substrate are different from each other. A semiconductor laser that emits laser light having a wavelength is preferable.

  The laminated substrate preferably has a light receiving element disposed on the surface of the substrate.

  The method of manufacturing a semiconductor laser according to the present invention has a rectangular opening on a laminated substrate that is laminated so that the surfaces of the plurality of substrates are parallel to each other with an intermediate layer made of a material different from that of the substrate interposed between the plurality of substrates. A first rectangular opening pattern forming step for forming a first rectangular opening pattern, and a halfway stop etching for etching the first substrate in the uppermost layer of the laminated substrate to the middle using the first rectangular opening pattern as a mask A step of removing the first rectangular opening pattern, a second rectangular opening pattern forming step of forming a second rectangular opening pattern having a plurality of openings on the laminated substrate, and the first rectangle A first substrate etching step of etching the first substrate in the uppermost layer of the laminated substrate using the opening pattern as a mask until reaching the first intermediate layer immediately below the first substrate; A third rectangular opening pattern forming step of forming a third rectangular opening pattern that covers at least one of the rectangular grooves formed by the one substrate etching step and exposes the other rectangular groove opening; and the second rectangle A first intermediate layer etching step in which the first intermediate layer is etched using the opening pattern as a mask until reaching the second substrate immediately below the first intermediate layer; and the second substrate is used as the mask in the second rectangular opening pattern. A second substrate etching step of etching until reaching the second intermediate layer directly below, and one or more semiconductor lasers mounted on the bottom of each rectangular groove formed through the first substrate etching step to the second substrate etching step And a semiconductor laser mounting step for mounting.

  The first substrate and the second substrate have a <110> direction in the plane and surfaces having a (100) plane inclined within a range of 5 to 15 ° with the <110> direction as a rotation axis. It is a silicon (100) substrate, the halfway stop etching step is preferably performed by anisotropic dry etching, and the first substrate etching step and the second substrate etching step are preferably performed by wet etching using an alkaline aqueous solution. .

  In the first intermediate layer etching step, it is preferable that etching is performed using an etchant having an etching rate with respect to the first intermediate layer higher than that with respect to the first substrate and the second substrate.

  The optical pickup device of the present invention includes a semiconductor laser device including a plurality of semiconductor lasers, a light branching unit that branches reflected light reflected by an optical information recording medium, and the light emitted from the semiconductor laser device, In the optical pickup device including a light receiving element that receives light branched by the light branching unit, the semiconductor laser device of the present invention is used as the semiconductor laser device.

  The light receiving element is preferably arranged on the same substrate as the semiconductor laser device.

  The semiconductor laser device is a semiconductor laser device that emits laser beams of different wavelengths, and the light receiving element is arranged at a position where the same light receiving element receives light of different wavelengths diffracted by the light branching unit. Preferably it is.

  As described above, according to the present invention, in a light receiving / emitting element that can be used in a semiconductor laser device, an optical disk device, etc., optical components such as a light receiving element, a lens, and a hologram can be shared by two semiconductor lasers. A light emitting element and a light receiving and emitting element mounting substrate can be realized.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First embodiment)
1A and 1B are diagrams showing the configuration of the semiconductor laser device according to the first embodiment of the present invention. FIG. 1A is a plan view and FIG. 1B is a straight line shown in FIG. It is sectional drawing in AA '.

The laminated substrate 1 has a structure in which three silicon substrates 2a, 2b, and 2c are bonded to each other with the SiO ₂ layers 3a and 3b interposed therebetween, and the substrates 2a, 2b, and 2c are arranged in order from the surface side of the substrate 1. ing. Among these, at least the substrates 2a and 2b have silicon having a <110> direction in the plane and a surface in which the (100) plane is inclined within a range of 5 to 15 [deg.] With the <110> direction as a rotation axis. A (100) substrate is used and bonded so that the surface crystal orientations face each other, that is, with the crystal surface orientations rotated by 180 ° on each other substrate. The thicknesses of the substrates 2a and 2b are the same as the depth of the rectangular groove formed on each substrate, and this depth is preferably determined in consideration of the optical distance when the semiconductor laser is mounted on the bottom surface of the rectangular groove.

On the surface of the substrate 2a, light receiving elements 4a and 4b, wirings (not shown), and various integrated circuits (not shown) are formed using a normal LSI manufacturing technique. A first rectangular groove 5 and a second rectangular groove 6 are formed on the semiconductor substrate 2a, and a micromirror is formed on an inclined surface forming an angle of 45 ° with the surface of the substrate 1 among the side surfaces of each groove. 7a and 7b are formed. Of these, the groove 6 passes through the substrate 2a, the SiO ₂ layer 3a and the substrate 2b and reaches the SiO ₂ layer 3b, and the micromirror 7b is formed on the side surface of the groove 6b provided in the substrate 2b. Is formed.

  The micromirrors 7a and 7b are opposed to each other when viewed from above the substrate, and in a direction (hereinafter referred to as tangential direction) perpendicular to the radial direction (hereinafter referred to as radial direction) of an optical disk (not shown). The grooves 5 and 6 are formed so that the distance between the micromirrors is as small as possible. Further, semiconductor lasers 8 and 9 having different oscillation wavelengths are mounted on the bottom surfaces of the grooves 5 and 6, respectively.

  It is desirable that the light receiving elements disposed on the substrate 2a and the micromirrors 7a and 7b in the radial direction are disposed with the center line of the rectangular grooves 5 and 6 in the radial direction as symmetry lines. Further, each of the light emitting points of the semiconductor lasers 8 and 9 is mounted on the center line.

  Light emitted from the semiconductor lasers 8 and 9 is reflected upward by the micromirrors 7a and 7b perpendicular to the paper surface. Each reflected light is reflected by an optical disk (not shown), and the returned reflected light is received by the corresponding light receiving elements 4a and 4b.

  In this semiconductor laser device, the apparent distance between the emission points in the tangential direction is the depth of the rectangular grooves 5 and 6, the distance between the micromirrors 7 a and 7 b, and the height from the bottom of the semiconductor lasers 8 and 9 to the emission point. And is independent of the distance between the micromirror and the front end face of the semiconductor laser. Therefore, the distance between the light emitting points and the optical distance of each semiconductor laser can be considered individually, and the optical distance in the semiconductor lasers 8 and 9 can be set freely to some extent.

  In the present embodiment, the groove 6 has a “shape” shape in which a side surface close to the groove 5 is partially folded in a direction in which the semiconductor laser 9 is disposed.

  Advantages of such a configuration will be described below.

  As described above, the slopes of the rectangular grooves formed by anisotropic wet etching of the silicon substrates 2a and 2b, and thus the angles between the micromirrors 7a and 7b formed on the slopes of the grooves 5 and 6 and the substrate surface. Is uniquely determined by the crystal orientation of each substrate.

  When the micromirror angle is a °, the slope angle on the side opposite to the micromirror is approximately 1 (110−a) °. Here, assuming that the thickness of the substrate 2a is D and etching for groove formation is performed until the substrate 2a penetrates the substrate, the tangential dimension of the inclined surface on the side opposite to the micromirror in the groove is D / tan (110 -A). That is, since the separation distance in the tangential direction between the micromirror 7b and the micromirror 7a formed in the rectangular grooves 5 and 6 is determined by the distance of D / tan (110-a), the light of the semiconductor lasers 8 and 9 This is a factor that the shaft spacing cannot be reduced.

  Therefore, in the present embodiment, as shown in FIG. 1A, a part of the inclined surface provided with the micromirror is folded back, and the thickness D of the substrate 2a is effectively reduced to thereby reduce the tangential direction. , The separation distance D / tan (110-a) is reduced, and the optical axis interval of the semiconductor lasers 8 and 9 is reduced.

  As a result, in an integrated semiconductor laser device equipped with two different lasers, it is possible to make the outgoing optical axes of the respective lasers closer to each other, thereby reducing the number of optical components, resulting in cost reduction, and simplification of the device.

  However, the folding amount has an upper limit for the following reason. If the amount of folding is too large, the thickness of the portion of the substrate 2a that supports the micromirror 7a is reduced and the mechanical strength is reduced, so that troubles such as breakage are likely to occur. The other is that the micromirror The light emitted from the semiconductor laser 9 reflected by the light 7b and emitted upward is “eave”, and a necessary light quantity cannot be obtained. The latter will be further described in detail.

  2 is an enlarged cross-sectional view of the vicinity of the groove of the semiconductor laser device according to the first embodiment of the present invention. FIG. 2A is an enlarged cross-sectional view of the groove without eaves, and FIG. It is a cross-sectional enlarged view of the groove | channel in which the eaves 10 were formed. The states of light emitted from the semiconductor lasers 8 and 9 are shown.

  As can be seen from FIG. 2A, when the side surface of the groove provided with the micromirror is a simple slope, the side surface itself does not block the emitted light.

  However, as shown in FIG. 2B, in the case where the side surface of the groove is folded and the upper portion becomes the eaves 10, the emitted light from the laser reflected by the micromirror depends on the amount of folding. A part of the eaves is applied to the eaves 10 and is scattered and cannot be used effectively.

  The allowable amount of folding is determined by the radiation angle of the laser beam after being reflected by the mirror, and this angle itself is determined by the thickness of the semiconductor laser, the height of the micromirror, the distance between the semiconductor laser and the micromirror, etc. Is done.

  Here, an allowable upper limit amount of folding is calculated in actual use. First, in the case of FIG. 2A, when the thickness of the semiconductor laser is 150 μm, the emission point position is 10 μm above the bottom, the distance between the semiconductor laser and the top of the micromirror is 85 μm, and the height of the micromirror is 55 μm. The angles 21 and 22 are about 12 ° and 34 °, respectively. When this result is applied to the arrangement of FIG. 3, the allowable upper limit amount of folding is about 30 μm at the maximum.

  As shown in FIG. 4, unlike the present embodiment, when there is no eaves on the inclined surface, the distance between the outgoing optical axes of the respective semiconductor lasers directed above the substrate is estimated to be about 100 μm when calculated using the above values. It is.

  According to the present embodiment, the folding can be made up to a maximum of about 30 μm, so that the optical axis interval can be reduced by that amount and reduced to about 70 μm.

  FIG. 4 and FIG. 5 show manufacturing process flow charts of the semiconductor laser device according to the present embodiment.

  First, a first mask layer 42 having an opening 41a is formed on the substrate 2a (FIG. 4A), and the substrate 2a immediately below the opening 41a is etched to form a groove 43 (FIG. 4B). ). At this time, the etching is performed by a method that is not affected by the crystal orientation of the substrate, for example, anisotropic dry etching, and after the etching, the first mask layer 42 is removed.

  Next, a second mask layer 45 having openings 41b and 44 is formed on the substrate 2a (FIG. 4C), and the substrate 2a immediately below the openings 41b and 44 is etched to form grooves 5 and 6a. (FIG. 5D). At this time, by anisotropic wet etching of the silicon substrate 2a using an alkaline solution such as KOH, the side surface of the groove is exposed to the (111) plane and the same index surface. As shown in the plan view of FIG. 4C, when the opening 41b is viewed from above, the opening 41b is provided so as to surround the groove 43. One side is in a substantially overlapping state.

  By performing the anisotropic wet etching in this state, a fold is formed on the side surface of the groove 6 a facing the groove 5.

  This will be described in further detail. When the anisotropic wet etching is performed on the substrate 2a immediately below the opening 41b, the portion of the groove 43 that has already been formed proceeds as follows.

  First, the bottom area of the bottom surface of the groove 43 decreases as the etching progresses, and finally ends in an inverted pyramid shape. However, when the entire etching just under the opening 41b proceeds, the processed shape is finally absorbed.

  On the other hand, on the side surface of the groove 43, the etching progresses to the outside of the original opening 41a viewed from above as the etching proceeds. Accordingly, the upper surface of the groove 43 has a reverse taper shape with the bottom surface before anisotropic wet etching as a boundary, and the lower surface has a forward taper shape.

  Of these, except for the surface facing the groove 5, when the entire etching just below the opening 41 b proceeds in the same manner as described above, the processed shape is finally absorbed, but the side surface facing the groove 5 is originally from above. Since the opening 41b and the groove 43 almost overlap each other as seen, the reverse tapered shape and the forward tapered shape are combined without being absorbed by the entire processed shape.

  As a result, folding as shown in FIG. 5D is formed. At this time, the folding amount is about half of the dry etching depth of the groove 43.

After anisotropic wet etching is performed until it penetrates the substrate 2a and reaches the SiO ₂ layer 3a, the bottom surface of the groove 5 is covered with a resist mask or the like (not shown), and then the SiO ₂ layer on the bottom surface of the groove 6a. Is etched to expose the substrate 2b (FIG. 5E).

  After removing the resist mask, the substrate 2b is etched by anisotropic wet etching to form a groove 6b (FIG. 5F).

The bottom surface of the groove 6b reaches the SiO ₂ layer 3b, and the (111) plane and the surface having the same index as the groove 5 and the groove 6a are exposed on the side surface. In this case, the opposing side surfaces of the grooves 5 and 6b as viewed from above the substrate form an angle of 45 ° with the substrate surface. After depositing a gold thin film on these slopes and patterning to provide micromirrors 7a and 7b, semiconductor lasers 8 and 9 are placed on the bottom surfaces of grooves 5 and 6b, respectively.

According to the present embodiment, by using a substrate in which a plurality of silicon substrates are bonded via the SiO ₂ layer, by providing grooves so as to reach different substrates from the surface of the laminated substrate, the SiO ₂ layer is Since it becomes an etch stop layer at the time of anisotropic wet etching, variation in flatness of the groove bottom due to etching does not occur. Also, the surface flatness of the silicon substrate is high, and the SiO ₂ layer is formed by thermal oxidation of the silicon substrate surface or oxygen ion implantation into the substrate and subsequent heat treatment, and maintains a very high surface flatness. For this reason, in addition to the above effects, the groove bottom keeps a very high flatness.

  By adopting a configuration in which a semiconductor laser is mounted on each bottom surface, variations in the laser output optical axis can be greatly reduced, and each laser beam can be accurately emitted 90 ° above the substrate.

In this embodiment, since the semiconductor lasers are mounted at different depths when viewed from the surface of the uppermost substrate, the optical path lengths to the optical disks are different. On the other hand, these optical paths become apparent resonators for the semiconductor lasers 8 and 9, so that when this length is changed, the noise characteristics of the semiconductor laser are periodically deteriorated. Such a position where the noise characteristic deteriorates is generally called a scoop position. Its period is the effective refractive index of the semiconductor laser n _eff, when the resonator length is L, is represented by _{C = 2 × n eff × L} , generally C is called the coherence length. Normally, in the design of an optical pickup device, the apparent resonator length (optical path length) formed by the optical disc and the emission end face of the semiconductor laser is set to be approximately at the center of the scoop position.

  Here, in the case where a plurality of semiconductor lasers having different wavelengths of emitted light are mounted, the optical path lengths are equal if a groove having the same depth is formed on one substrate and the semiconductor lasers are mounted on the bottom surface thereof, respectively. Because it is fixed, even if the noise characteristics of one semiconductor laser can be kept good, other semiconductor lasers have different characteristics, so they approach the scoop position and the noise characteristics may deteriorate. is there. In order to prevent the deterioration of the noise characteristics, it is necessary to finely adjust the distance between the optical disk and the semiconductor laser device when the semiconductor laser is arranged by optimizing the respective optical path lengths, and the assembly process of the optical pickup device is complicated. To do.

  However, according to the semiconductor laser device of the present embodiment, as shown in FIG. 1, the distance between the semiconductor lasers 8 and 9 and the optical disk (not shown) is set to the optimum depth of the grooves 5 and 6. It can be easily adjusted by setting the value. Here, in order to suppress deterioration of noise characteristics, it is preferable that the semiconductor laser mounted on the deeper rectangular groove has a longer wavelength of emitted light than the semiconductor laser mounted on the shallower groove. .

The depth of the groove can be adjusted to an arbitrary and constant depth by selecting optimum thicknesses of the silicon substrates 2a and 2b and SiO ₂ layers 3a and 3b used in the laminated substrate 1. it can. Therefore, in the semiconductor laser device, the semiconductor lasers 8 and 9 can be mounted with higher accuracy in three dimensions than in the past.

In the present embodiment, although placing the semiconductor laser on the upper surface of the SiO ₂ layer may be placed on the silicon substrate surface thereunder by etching the SiO ₂ layer. In that case, the silicon substrate serves as a heat sink to improve heat dissipation.

  In addition, the first mask layer 42 is once removed and then the second mask layer 45 is formed, but the first mask layer is left without being removed, and the opening 41b and the groove 43 are formed in the second mask layer 45. It may be.

  The material and manufacturing method of the micromirror are not particularly limited to this embodiment as long as the laser beam can be effectively reflected.

(Second Embodiment)
FIG. 6 is a schematic diagram showing the configuration of the optical pickup according to the second embodiment of the present invention.

  The semiconductor laser device 51 in the figure is the same as that shown in the first embodiment of the present invention.

  As shown in the figure, the optical pickup device is a device that reads information recorded on an optical disk 55, and includes a semiconductor laser device 51, an optical element 52, a collimator lens 53, and an objective lens 54.

  The semiconductor laser device 51 reflects the laser light emitted from the semiconductor lasers 8 and 9 by the micromirrors 7 a and 7 b and emits the laser light toward the optical element 52.

  In the optical element 52, a diffraction grating 56 (not shown) for dividing incident light is formed on the surface on the semiconductor laser device 51 side. After the diffraction grating divides incident light into three beams, each beam Is incident on the collimating lens 53.

  The collimating lens 53 makes incident light enter the objective lens 54 as parallel light.

  The objective lens 54 converges the incident light and irradiates the optical disc 55 with it.

  Information is recorded on the optical disk 55 by a number of projections called pits, and the amount of reflected light varies depending on the presence or absence of pits, but the laser light reflected by the optical disk 55 returns along the same path, and the objective lens 54, collimator Through the lens 53, the light is diffracted by a hologram 57 (not shown) formed on the surface of the optical element 52 on the optical disk side and reaches the light receiving elements 4 a and 4 b (not shown) provided on the upper surface of the semiconductor laser device 51. To do.

  Based on the detection values of the light receiving elements 4a and 4b, calculation for detecting a known tracking error or focus error is performed, and information recorded on the optical disc 55 is read.

  According to this embodiment, since the optical axis of each laser can be sufficiently close to the optical disc, and variations in the optical axis can be sufficiently reduced, even if a plurality of different lasers are arranged, they are almost the same. It can be regarded as one semiconductor laser device having a plurality of outgoing optical axes. As a result, an optical component such as an objective lens, a collimating lens, and a hologram can be shared in one set, and the number of components of the optical pickup can be greatly reduced. Further, the light receiving element that receives the reflected return light from the optical disk can be shared. Since this light receiving element is formed on the substrate using a known LSI manufacturing technique, the manufacturing process can be greatly shortened by sharing the light receiving element.

  Therefore, according to the present embodiment, it is possible to significantly reduce the manufacturing cost, shorten the manufacturing period, and provide a high-performance, high-quality two-wavelength optical pickup.

  The semiconductor laser device according to the present invention is particularly useful as an integrated semiconductor laser device used for a two-wavelength optical pickup.

BRIEF DESCRIPTION OF THE DRAWINGS It is the figure which showed the structure of the semiconductor laser apparatus in the 1st Embodiment of this invention, (a) is a top view, (b) is sectional drawing in the straight line A-A 'shown to (a). It is a cross-sectional enlarged view of the vicinity of the groove of the semiconductor laser device in the first embodiment of the present invention, (a) is an enlarged cross-sectional view of the groove without eaves, (b) is a cross-section of the groove where the eaves are formed Enlarged view 2A and 2B are explanatory views of the structure of the semiconductor laser device when no eaves are formed according to the first embodiment of the present invention, in which FIG. 1A is a plan view, and FIG. 2B is a straight line BB ′ shown in FIG. Sectional view at Manufacturing process flow chart of the semiconductor laser device in the first embodiment of the present invention Manufacturing process flow chart of the semiconductor laser device in the first embodiment of the present invention The schematic diagram which showed the structure of the optical pick-up in the 2nd Embodiment of this invention Cross-sectional structure diagram of a conventional semiconductor laser device The figure which showed the structure of the integrated semiconductor laser apparatus in a prior art

Explanation of symbols

Formed in a multilayer substrate 2a, 2b, 2c silicon substrate 3a, 3b SiO ₂ layer 4a, 4b receiving element 5 first rectangular groove 6 second rectangular groove 6b substrate 2b formed on the second rectangular groove 6a substrate 2a Second rectangular groove 7a micromirror 7b formed in groove 5 micromirror 8 formed in groove 6 semiconductor laser 10 eaves 41a, 41b opening 42 first mask layer 43 groove 44 opening 45 Second mask layer 51 Semiconductor laser device 52 Optical element 53 Collimating lens 54 Objective lens 55 Optical disk 56 Diffraction grating 57 Hologram 61 Semiconductor substrate 62 Semiconductor laser 63 Micromirror 71 Substrate 72, 73 Semiconductor laser 74 Mirror 74a, 74b Mirror surface

Claims (13)

A plurality of substrates each having a rectangular shape in plan view on a surface of the laminated substrate in which a plurality of substrates are laminated so that the substrate surfaces are parallel to each other with an intermediate layer made of a material different from the substrate interposed between the plurality of substrates. A rectangular groove is provided,
Among the plurality of rectangular grooves, at least a pair of adjacent rectangular grooves are arranged such that the ridge lines of the openings are parallel to each other, and one is in the first substrate on the outermost surface and the other is in the outermost surface. It is formed so as to reach a second substrate located immediately below the substrate on the surface,
One or more semiconductor lasers are placed on the bottom of each rectangular groove,
The side surface of the rectangular groove is formed such that a region irradiated with a laser beam emitted from a semiconductor laser mounted on the bottom of the rectangular groove forms an angle of 40 ° to 50 ° with respect to the surface of the laminated substrate. Has been
In the region irradiated with the laser beam, a micromirror is formed that reflects the irradiated laser beam and guides it above the laminated substrate.
The pair of rectangular grooves are arranged at positions facing each other when viewed in a plan view on each side of the rectangular grooves where the laser beam hits.
Among the side surfaces including the region irradiated with the laser beam in the other rectangular groove reaching the second substrate, the side surface has a cross-sectional shape folded halfway in the substrate on the outermost surface. A semiconductor laser device. 2. The bottom of each of the plurality of rectangular grooves is formed by an intermediate layer surface that is exposed by reaching the boundary surface between the substrate and the intermediate layer in the depth direction. Semiconductor laser device. 2. The semiconductor according to claim 1, wherein the bottoms of the plurality of rectangular grooves are each formed by a substrate surface that is exposed by reaching a boundary surface between the intermediate layer and the substrate in a depth direction. Laser device. The semiconductor laser device according to claim 1, wherein the intermediate layer and the substrate are made of materials having different etching rates with respect to each of the acidic solution and the alkaline solution. The plurality of substrates are silicon (100) substrates having a <110> direction in a plane and a surface having a (100) plane tilted in a range of 5 to 15 degrees with the <110> direction as a rotation axis. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is a semiconductor laser device. Since at least one of the plurality of rectangular grooves reaches a substrate different from the other rectangular grooves, the semiconductor lasers mounted in the rectangular grooves having different depths from the surface of the laminated substrate are different from each other. 6. The semiconductor laser device according to claim 1, wherein the semiconductor laser device emits laser light having a wavelength. The semiconductor laser device according to claim 1, wherein a light receiving element is disposed on the surface of the multilayer substrate. A first rectangular opening pattern having a rectangular opening is formed on a laminated substrate that is laminated so that surfaces of the plurality of substrates are parallel to each other with an intermediate layer made of a material different from the substrate interposed between the plurality of substrates. 1 rectangular opening pattern forming step;
Etching the first substrate in the uppermost layer of the multilayer substrate to the middle using the first rectangular opening pattern as a mask,
Removing the first rectangular opening pattern;
A second rectangular opening pattern forming step of forming a second rectangular opening pattern having a plurality of openings on the laminated substrate;
A first substrate etching step of etching the first substrate in the uppermost layer of the multilayer substrate using the first rectangular opening pattern as a mask until reaching the first intermediate layer immediately below the first substrate;
A third rectangular opening pattern forming step of forming a third rectangular opening pattern that covers at least one of the rectangular grooves formed by the first substrate etching step and exposes the other rectangular groove opening;
A first intermediate layer etching step of etching the first intermediate layer until reaching the second substrate immediately below the second rectangular opening pattern as a mask;
A second substrate etching step of etching the second substrate using the second rectangular opening pattern as a mask until reaching the second intermediate layer immediately below the second substrate;
A semiconductor laser device manufacturing method comprising: a semiconductor laser mounting step of mounting one or more semiconductor lasers on the bottom of each rectangular groove formed from the first substrate etching step to the second substrate etching step. Method. The first substrate and the second substrate have a <110> direction in the plane and surfaces having a (100) plane inclined within a range of 5 to 15 ° with the <110> direction as a rotation axis. A silicon (100) substrate, wherein the halfway stop etching step is performed by anisotropic dry etching, and the first substrate etching step and the second substrate etching step are performed by wet etching using an alkaline aqueous solution. A method for manufacturing a semiconductor laser device according to claim 8. 9. The etching according to claim 8, wherein the first intermediate layer etching step is performed by using an etchant having an etching rate with respect to the first intermediate layer higher than that with respect to the first substrate and the second substrate. 10. A method for manufacturing a semiconductor laser device according to 9. A semiconductor laser device comprising a plurality of semiconductor lasers; a light branching means for branching the reflected light reflected by the optical information recording medium; and a light split by the light branching means. In an optical pickup device comprising a light receiving element that
An optical pickup device using the semiconductor laser device according to claim 1 as the semiconductor laser device. 12. The optical pickup device according to claim 11, wherein the light receiving element is disposed on the same substrate as the semiconductor laser device. The semiconductor laser device is a semiconductor laser device that emits laser light of different wavelengths, and the light receiving element is disposed at a position where the same light receiving element receives light of different wavelengths diffracted by the light branching means. The optical pickup device according to claim 11 or 12,

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