JP2002269798A - Multi-wavelength light source pickup module and optical pickup device - Google Patents

Abstract

(57) Abstract: A multi-wavelength light source pickup including a microprojection having a simple and excellent flatness inclined surface on a substrate, a semiconductor laser element of a plurality of wavelengths, and an integrated photodetector. It is an object of the present invention to provide a module for use and an optical pickup device using the module. According to the present invention, in a multi-wavelength light source pickup module for use in an optical pickup device using a plurality of light sources having different wavelengths, a semiconductor substrate and a first laser beam disposed on the semiconductor substrate are transmitted. A first semiconductor laser element 1 for emitting light, a second semiconductor laser element 2 disposed on a semiconductor substrate and emitting a second laser beam having a wavelength different from that of the first semiconductor laser element, and formed on the semiconductor substrate In addition, a configuration is provided in which the microprojections 4 having flat inclined surfaces for reflecting the first and second laser beams in predetermined directions are provided, and the photodetectors 7 formed on the semiconductor substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical pickup device (optical head device) using a plurality of light sources having different wavelengths.
More particularly, the present invention relates to a multi-wavelength light source pickup module provided with a plurality of light sources having different wavelengths used in the optical pickup device, and an optical pickup device using the multi-wavelength light source pickup module.

[0002]

2. Description of the Related Art In recent years, a recording medium is required to have a large recording capacity as the amount of information to be handled is increased. Optical recording media, which is one of large-capacity information recording media, includes:
Existing compact disc (hereinafter referred to as CD) or WO
CD capable of RM (Write Once Read Many) recording
(Hereinafter referred to as CD-R), and rewritable CD
(CD-RW) and the like, but recently, a digital versatile disc (Digital Versatil) having a recording capacity 6 to 7 times that of a CD-based optical disc is known.
e Disc; hereinafter, referred to as DVD) is being developed.
This DVD-type optical disc includes a read-only type (DV
D-ROM), one-time rewrite type (DVD-R), rewritable type (DVD-ROM, DVD-RW, DVD + R)
W).

[0003] This DVD not only has a higher recording density (ie, track density) than CDs and CD-Rs, but also has a shorter distance from the surface of the optical disk to the information recording surface.
For example, a DVD has a distance from the disk surface to the information recording surface, that is, a substrate thickness of the information recording medium is 0.6 mm, while a CD and a CD-R have a thickness of 1.2 mm.
The information recording surfaces of DVD and CD-R have different reflectivities depending on the wavelength of the light beam. Further, the reflectivity of the information recording surface of the CD-R becomes maximum when the wavelength is 780 nm, whereas the reflectivity of the information recording surface of the DVD-R becomes maximum when the wavelength is 650 nm. Since optical disks having different structures and characteristics are commonly used,
An optical pickup device is also required to be able to record, reproduce, and erase information on optical disks of these different standards, ie, CDs, CD-Rs, and DVDs.

In order to enable recording, reproducing, and erasing of information on all such CD and DVD optical discs, a two-beam type optical pickup device using two light sources has been proposed. Have been. As shown in FIG. 6, for example, this two-beam optical pickup device
It comprises two light sources 30, 32, which are separated from each other and generate a 50 nm light beam and a 780 nm light beam, respectively. Since the optical paths of the light beams from the separated light sources 30 and 32 must be matched, a beam splitter 34 is provided.

In FIG. 6, a first light source 30 generates a light beam having a wavelength of 650 nm (hereinafter, referred to as a first light beam B1) when a DVD-type optical disk 38 is accessed, and the first light source 30 emits a first light beam. The light beam B1 is directed to the first beam splitter 34 via the collimator lens 31. On the other hand, the second light source 32 is a CD or a CD-R or a CD-R.
780 when using a CD-type optical disc 39 such as RW
A light beam having a wavelength of nm (hereinafter, a second light beam B2
) And supplies the second light beam B2 to the first beam splitter 34 via the collimator lens 33. The first beam splitter 34 allows the first light beam B1 to pass through as it is, and the second light beam B2 is bent at a right angle and reflected to match the traveling path of the first light beam B1 with the traveling path of the second light beam B2. Let it.

The first light beam B1 from the first beam splitter 34 is focused in the form of a spot on the information recording surface of a DVD-based optical disk 38 via a second beam splitter 35, a right-angle reflecting mirror 36, and an objective lens 37. You. The light beam reflected by the information recording surface of the DVD-based optical disk 38 is directed to the objective lens 37, the right-angle reflecting mirror 36, the second
The light reaches the multi-split photodetector 41 via the beam splitter 35 and the condenser lens 40. Similarly, the second light beam B2 from the first beam splitter 34 also passes through the second beam splitter 35, the right-angle reflecting mirror 36, and the objective lens 37, and is collected on the information recording surface of a CD optical disc 39 such as a CD or CD-R. After being illuminated, the light is reflected by the information recording surface of the CD optical disk 39, and is reflected by the objective lens 37, the right-angle reflecting mirror 36, the second beam splitter 35, and the condenser lens 40.
And reaches the multi-segmented photodetector 41. The multi-segment photodetector 41 converts the light amount of the light beam incident from the condenser lens 40 into an electric signal. The electric signal is DV
Information recorded on the D-type optical disk 38 or the CD-type optical disk 39 is included.

[0007]

The above-described two-beam type optical pickup device requires the addition of two light sources and an optical system for matching the traveling paths of the light beams from these light sources. . Accordingly, the two-beam optical pickup device has disadvantages in that not only the configuration is complicated but also the volume is increased and the size is increased. In order to improve the disadvantages of the two-beam type optical pickup device, a CD, a CD-R and a D
In order to access all the VDs, a hologram type optical pickup device, an optical pickup device of a liquid crystal blocking type or an annular shielding type, and the like have been proposed.

The hologram type optical pickup device utilizes a hologram lens so that two diffracted light beams having different beam bundle diameters are incident on an objective lens.
The focus is formed on all the information recording surfaces of the CD, CD-R or DVD. Next, the liquid crystal cutoff type optical pickup device uses a liquid crystal plate and a polarizing plate to adjust the luminous flux diameter of the light beam incident on the objective lens to control the CD and the CD.
The light beam is focused on the information recording surface of -R or the information recording surface of the DVD. An annular pickup type optical pickup device uses an objective lens having an annular frame formed on its surface to prevent side lobes from being generated.
The light beam is focused on both the information recording surface of D and CD-R and the information recording surface of DVD.

These optical pickup devices use a CD, CD-R by changing the focal length of an objective lens.
In addition, the light beam could be focused on the entire information recording surface of the DVD, but the information recorded on the CD-R could not be read. This is the information recording surface of CD-R and DV
This is because the reflectivity of D on the information recording surface varies depending on the wavelength of the light beam. That is, the reflectivity of the information recording surface of the CD-R becomes maximum when the wavelength is 780 nm, while the reflectance is
The reflectance of the information recording surface of VD becomes maximum when the wavelength is 650 nm. As a result, these optical pickup devices of the hologram type, the liquid crystal blocking type or the annular blocking type could not be used for all CDs, CD-Rs and DVDs.

In order to solve such a problem, there has been proposed a different wavelength light source module capable of emitting light beams having different wavelengths in the same optical axis direction (Japanese Patent Application Laid-Open No. 11-39684). In this different wavelength light source module, a plurality of inclined surfaces are formed on the surface of the support, and a light source that emits light beams having different wavelengths is arranged so as to face the inclined surfaces. Each inclined surface is formed at an angle of 45 ° with respect to the support surface, and more specifically, a submount having a triangular cross section in which an inclined surface is formed at an angle of 45 ° on the support surface. A triangular pyramid submant and other polygonal submant slopes are used. In such a method, the support having the inclined surface is formed by anisotropic etching of silicon. However, in this conventional example, since the photodetector for detecting the laser beam reflected from the disk surface is configured separately from the different wavelength light source module, there is little effect in terms of miniaturization and cost reduction of the optical pickup device. Not obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor device having a plurality of wavelengths of semiconductor lasers provided on a substrate with simple projections having an inclined surface having excellent flatness and a light detection. It is an object of the present invention to provide an integrated multi-wavelength light source pickup module in which a light source is integrated, and to provide a small and low-cost optical pickup device equipped with the multi-wavelength light source pickup module.

[0012]

According to a first aspect of the present invention, there is provided a multi-wavelength light source pickup module used in an optical pickup device using a plurality of light sources having different wavelengths. A semiconductor substrate, a first semiconductor laser element disposed on the semiconductor substrate and emitting a first laser beam, and a second laser disposed on the semiconductor substrate and having a different wavelength from the first semiconductor laser element A second semiconductor laser device for emitting a beam, and the first and second semiconductor laser devices formed on the semiconductor substrate.
And a micro-projection having a flat inclined surface for reflecting the laser beam in a predetermined direction, and a photodetector formed on the semiconductor substrate.

According to a second aspect of the present invention, in the module for a multi-wavelength light source pickup according to the first aspect, the minute projections are formed by etching, and KOH and (CH ₃ ) ₄ are formed when the minute projections are etched. It is characterized by using NOH as an etchant. The invention according to claim 3 is the module for a multi-wavelength light source pickup according to claim 1 or 2, wherein an SOI substrate is used as the semiconductor substrate, and the SOI substrate is anodically bonded to a glass substrate. Is what you do. According to a fourth aspect of the present invention, in the multi-wavelength light source pickup module according to the first, second or third aspect, a metal film or a retardation film is deposited on the minute projection. is there.

The invention according to claim 5 is the invention according to claims 1, 2, 3
Alternatively, in the multi-wavelength light source pickup module according to item 4, a plurality of semiconductor laser elements having different wavelengths are provided. According to a sixth aspect of the present invention, in the multi-wavelength light source pickup module according to the first, second, third, or fourth aspect, a plurality of semiconductor laser elements having different wavelengths are provided, and a distance between each semiconductor laser element and the minute projection is provided. Are arranged so as to be shifted by a predetermined distance for each of a plurality of semiconductor laser elements having different wavelengths. Furthermore, the invention according to claim 7 is the multi-wavelength light source pickup module according to any one of claims 1 to 6, wherein the minute protrusions having different lengths on one side and the other side on the semiconductor substrate. Is formed.

According to an eighth aspect of the present invention, there is provided an optical pickup device for recording, reproducing, or erasing information by focusing a laser beam from a light source on an optical recording medium, comprising a plurality of light sources having different wavelengths and a photodetector. An integrated module is provided, and a multi-wavelength light source pickup module according to any one of claims 1 to 7 is used as the module.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure, operation and operation of the present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a perspective view of a main part of a multi-wavelength light source pickup module according to an embodiment of the present invention. The module for picking up a multi-wavelength light source shown in FIG. 1 uses a silicon substrate as a semiconductor substrate 3, a first semiconductor laser element 1 arranged on the silicon substrate and emitting a first laser beam, and a A second semiconductor laser element 2 that is disposed and emits a second laser beam having a different wavelength from the first semiconductor laser element 1; and a first and second laser beams formed on a silicon substrate 3 and directed in a predetermined direction. And a quadrangular pyramid-shaped micro-projection (silicon projection) 4 having a flat inclined surface for reflecting light. Although not shown, a photodetector is integrally formed on the silicon substrate 3.

First and second reflective films are formed on the four inclined surfaces of the four-sided pyramid-shaped minute projections 4 formed on the upper surface of the silicon substrate 3. This reflection film is a reflection film for efficiently reflecting the laser beams from the respective semiconductor laser elements 1 and 2, and is composed of a metal or dielectric multilayer film. When the reflection film is a dielectric multilayer film, the reflectance can be selectively improved with respect to the wavelength of each of the semiconductor laser devices 1 and 2. Silicon substrate 3
A first semiconductor laser device 1 and a second semiconductor laser device 2 are respectively arranged on both sides of the inclined surface of the upper microprojection 4, that is, at positions facing the first and second reflection films, respectively.

The first semiconductor laser device 1 generates a laser beam having a wavelength of 660 nm. This wavelength 660
The laser beam of nm is reflected by the first reflection film formed on the inclined surface of the minute projection 4 and travels in a direction substantially perpendicular to the surface of the silicon substrate 3. On the other hand, the second semiconductor laser 2 generates a laser beam having a wavelength of 780 nm. This light beam having a wavelength of 780 nm is reflected by the second reflection film formed on the inclined surface of the minute projection 4 and travels in a direction substantially perpendicular to the surface of the silicon substrate 3. In this case, the minute projection 4
Is formed at an angle of 45 ° with respect to the surface of the silicon substrate 3, the optical axis of each laser beam is reflected by each reflection film and is perpendicular to the surface of the silicon substrate 3. Direction. That is, the optical axes of the laser beams emitted from both the semiconductor laser elements 1 and 2 are coincident, and both are perpendicular to the silicon substrate 3. Also, by reducing the size of the minute projections 4,
The distance between the two optical axes can be reduced. By reducing the distance between the optical axes, it is possible to reduce the axial deviation when the light enters the optical system. Therefore, a laser beam spot of two wavelengths formed on the optical recording medium can be formed satisfactorily. It is possible to improve the accuracy of recording and reproduction.

Although not shown in FIG. 1, a cap is formed above the silicon substrate 3 so as to surround the silicon substrate 3. The cap keeps the periphery of the semiconductor laser devices 1 and 2 mounted on the silicon substrate 3 in a vacuum state and protects the semiconductor laser device from minute dust such as dust.

Next, FIG. 2 is a sectional view showing a schematic main configuration of an optical pickup device using the multi-wavelength light source pickup module of the present invention.
The multi-wavelength light source pickup module 8 having the configuration shown in FIG. 1 and the hologram element 9 disposed above the substrate of the multi-wavelength light source pickup module 8 are provided. Although not shown, the hologram element 9
An optical system including a collimator lens, a quarter-wave plate, an objective lens, and the like is disposed in the upward direction. Further, an N-type silicon substrate is used as the semiconductor substrate 3 of the multi-wavelength light source pickup module 8, and on the N-type silicon substrate 3, a P-type diffusion layer 5 selectively formed and serving as a light receiving region is formed. Al formed by vapor deposition on a P-type diffusion layer
A photodetector 7 including the electrode 6 is formed.

In FIG. 2, the laser beam emitted from one of the first and second semiconductor laser elements 1 and 2 disposed on the silicon substrate 3 of the multi-wavelength light source pickup module 8 is The light is reflected by the minute projections 4 formed thereon, deflected in a direction perpendicular to the surface of the silicon substrate 3, and emitted upward in the substrate. The laser beam emitted upward from the substrate passes through the hologram element 9 and passes through an optical system (not shown) including a collimator lens, a quarter-wave plate, an objective lens, and the like, and then an optical recording medium (CD system, not shown). Alternatively, the light is condensed on the information recording surface of a DVD optical disk to form a spot. The laser beam reflected by the information recording surface of the optical disk returns on the same optical path and enters the hologram element 9. Then, by forming a predetermined pattern on the hologram element 9, the laser beam is deflected to the light receiving region of the photodetector 7 on the silicon substrate 3.

The laser beam from the optical disk is deflected by the hologram element 9 and is incident on the light receiving region (P-type diffusion layer) 5 of the photodetector 7 so that the PN between the P-type diffusion layer 5 and the N-type silicon substrate 3 is reduced. Electron-hole pairs are generated at the junction. The generated carriers are drifted by the electric field in the depletion layer and are extracted from the Al electrode 6 as a photocurrent. By forming the light receiving area (P-type diffusion layer) 5 in a predetermined pattern, only the information signal detection of the laser light reflected by the optical disk by the photocurrent taken out from each electrode formed in the respective light receiving area. But not
The servo function (tracking servo signal, focus servo signal) or the like can be detected based on the change in the condensing position or shape of the laser light.

Next, a method for manufacturing silicon projections using an SOI substrate will be described with reference to FIG. First, an active silicon layer 11c is formed on a transparent substrate (for example, a glass substrate) 12.
An SOI (Silicon On Insulator) substrate 11 composed of a silicon oxide film layer 11b and a substrate silicon layer 11a is bonded by anodic bonding (FIG. 3A). Here, first, the substrate silicon layer 11a is made of KOH or (CH ₃ ) ₄ NOH (T
It is selectively removed using a MAH (Tetramethyl ammonium hydroxide) solution to expose the silicon oxide film layer 11b (FIG. 3B). Further, the silicon oxide film layer 11b
Is removed using an HF solution to form a substrate (silicon substrate) 3 having an active silicon layer 11c on a transparent substrate 12 (FIG. 3C). A square resist pattern 13 is formed on the active silicon layer 11c of the silicon substrate 3 by using a photoresist technique of a semiconductor process (FIG. 3D). This square resist pattern 1
3 is formed in a region where the silicon projection 4 is formed. The height of the resist pattern 13 needs to be 0.5 μm or more, more preferably 1 μm or more. Using this resist pattern 13 as a mask, the active silicon layer 11c
Is first etched with a KOH solution, further etched with a TMAH solution, and then the resist pattern 13 is removed, whereby the minute projections 4 can be formed on the silicon substrate 3 (FIGS. 3E and 3F). ). Here, when etching is performed along the (11 1) plane of silicon as a substrate, minute projections having an inclined surface of 54 degrees can be formed. On the other hand, by adjusting the etching rates in the (100) plane and the (1110) plane, it is possible to form the silicon micro-projections 4 having a 45 ° inclined surface on the silicon substrate 3. Was. Small protrusions 4 on silicon substrate 3
Is formed, the above-described photodetector (not shown) is formed on the silicon substrate 3, and two semiconductor laser elements 1 and 2 having different wavelengths are arranged to produce the multi-wavelength light source pickup module 8 ( FIG. 3 (g)).

Next, another method of manufacturing the silicon projection will be described with reference to FIG. First, on a transparent substrate (for example, a glass substrate) 12, an SOI (SlO) composed of an active silicon layer 11c, a silicon oxide film
The substrate 11 is bonded by anodic bonding (FIG. 4A). Here, first, the substrate silicon layer 11
a is KOH or (CH ₃ ) ₄ NOH (TMAH (Tet
ramethyl ammonium hydroxide)) solution to selectively remove the silicon oxide film layer 11b (FIG. 4).
(B)). A square resist pattern 13 is formed on the silicon oxide film 11b by using a photoresist technique of a semiconductor process (FIG. 4C). The square resist pattern 13 is formed in a region where the silicon projection 4 is formed. Using this resist pattern 13 as a mask, the silicon oxide film layer 11b is etched using an HF solution (FIG. 4D). Next, resist pattern 1
3 and the silicon oxide film layer 11b as a mask, the active silicon layer 11c is firstly etched with a KOH solution, further etched with a TMAH solution, and then a resist pattern 1 is formed.
By removing 3, a minute projection 4 can be formed on the silicon substrate 3 (FIG. 4E,
(F)). Here, when etching is performed along the (11 1) plane of silicon as a substrate, minute projections having an inclined surface of 54 degrees can be formed. On the other hand, by adjusting the etching rate in the (100) plane and the (1110) plane, the silicon micro-projections 4 having a 45 ° inclined surface could be formed on the silicon substrate 3. . After forming the minute protrusions 4 on the silicon substrate 3, the above-described photodetector (not shown) is formed on the silicon
The multi-wavelength light source pickup module 8 is manufactured by arranging the two semiconductor laser elements 1 and 2 (FIG. 4G).

In FIGS. 3 and 4, by forming the mask made of the resist pattern 13 into a rectangular shape, the bottom surface of the small pyramid projection 4 can be changed from a square shape to a rectangular shape. In this case, the first semiconductor laser element 1 is disposed at a position opposed to the quadrangular pyramid minute projections 4 ′ in the lateral direction as in the multi-wavelength light source pickup module 8 ′ having the configuration shown in FIG. The second, third, and fourth semiconductor laser elements 2-1, 2-2, and 2-3 can be arranged in the longitudinal direction of the minute projection 4 '. Therefore, in the configuration of FIG. 5, it is possible to arrange more wavelengths or more semiconductor laser elements in one module.

Further, in the multi-wavelength light source pickup module of the present invention, it is possible to arrange the semiconductor laser elements 1 and 2 at different intervals from the bottom surface of the minute projection 4. That is, in the optical pickup device having the configuration shown in FIG. 2, the collimator lens (above the hologram element 9) is arranged by changing the distance between each of the semiconductor laser elements 1 and 2 and the bottom surface of the minute projection 4. (Not shown) and the distance between the semiconductor laser elements 1 and 2 can be changed. Therefore, the chromatic aberration due to the different wavelength of the incident beam of the collimator lens can be canceled out by changing the distance between the semiconductor laser elements 1 and 2 and the bottom surface of the minute projection 4 at each wavelength, thereby favorably. Recording, reproduction, and erasure become possible.

[0027]

As described above, according to the first aspect of the present invention, in a multi-wavelength light source pickup module used for an optical pickup device using a plurality of light sources having different wavelengths, a semiconductor substrate and a semiconductor substrate are provided. A first semiconductor laser device arranged on the semiconductor substrate for emitting a first laser beam, and a second semiconductor arranged on the semiconductor substrate and emitting a second laser beam having a different wavelength from the first semiconductor laser device A laser element, a minute projection formed on the semiconductor substrate and having a flat inclined surface for reflecting the first and second laser beams in a predetermined direction, and a photodetector formed on the semiconductor substrate With this configuration, it is possible to easily align the optical axes of the laser beams emitted from the multi-wavelength light sources (first and second semiconductor laser elements). Ri, good recording, playback, it is possible to erase. Furthermore, since the light source unit and light receiving unit (photodetector) are integrally provided on the same substrate, adjustments required for ordinary optical systems can be reduced, and the number of components can be reduced, thus reducing costs. Therefore, it is possible to provide a multi-wavelength light source pickup module at lower cost.

According to a second aspect of the present invention, in the module for a multi-wavelength light source pickup according to the first aspect, the minute projections are formed by etching, and KOH and (CH ₃ ) ₄ are formed when the minute projections are etched. By using NOH as an etchant, it becomes possible to stably produce the inclined surfaces of the minute projections without variation. Also,
In the invention according to claim 3, in the multi-wavelength light source pickup module according to claim 1 or 2, the SOI substrate is used as the semiconductor substrate, and the SOI substrate is anodically bonded to the glass substrate, so that the substrate is flat. The handling can be facilitated by increasing the strength of the substrate and increasing the strength of the substrate. Furthermore, in the invention according to claim 4, in the multi-wavelength light source pickup module according to claim 1, 2, or 3, a metal film or a retardation film is deposited on the minute projection portion, so that the light source (first , The second semiconductor laser element) can efficiently irradiate the optical recording medium with the laser beam emitted therefrom, and higher-speed recording, reproduction, and erasing can be performed.

According to the fifth aspect of the present invention, the first, second and third aspects of the present invention are provided.
3. The multi-wavelength light source pickup module according to 3 or 4, wherein a plurality of semiconductor laser elements having different wavelengths are provided, so that laser beams having different wavelengths are selectively used according to the standard of the optical recording medium (optical disc). In addition to optical disks such as CDs, CD-Rs, and DVDs, all recording methods using a blue light source can be accurately recorded.
It becomes possible to reproduce and delete. According to a sixth aspect of the present invention, in the multi-wavelength light source pickup module according to the first, second, third, or fourth aspect, a plurality of semiconductor laser elements having different wavelengths are provided, and a distance between each semiconductor laser element and the minute projection is provided. Are arranged so as to be shifted by a predetermined distance for each of a plurality of semiconductor laser elements having different wavelengths, so that the chromatic aberration of the collimator lens can be offset, thereby enabling good recording, reproduction, and erasing. Become. Further, in the invention according to claim 7, in the multi-wavelength light source pickup module according to any one of claims 1 to 6, a minute projection having a different length from one side to another side is provided on the semiconductor substrate. The formation makes it possible to arrange more wavelengths or more semiconductor laser elements in one module.

According to an eighth aspect of the present invention, in an optical pickup device for recording, reproducing, or erasing information by focusing a laser beam from a light source on an optical recording medium, a plurality of light sources having different wavelengths and a photodetector are used. A multi-wavelength light source pickup module according to any one of claims 1 to 7, comprising an integrated module, and a laser beam emitted from a multi-wavelength light source. The axes can be easily aligned, and good recording, reproduction, and erasing can be performed on optical recording media of multiple standards.
A compact and low-cost optical pickup device can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a multi-wavelength light source pickup module according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a schematic main configuration of an optical pickup device using the multi-wavelength light source pickup module of the present invention.

FIG. 3 is a process explanatory view showing an example of a method for manufacturing silicon projections (fine projections) when an SOI substrate is used as a semiconductor substrate.

FIG. 4 is a process explanatory view showing another example of a method for manufacturing silicon projections (fine projections) when an SOI substrate is used as a semiconductor substrate.

FIG. 5 is a perspective view of a main part of a multi-wavelength light source pickup module according to another embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of an optical pickup device showing an example of a conventional technique.

[Explanation of symbols]

 1,2,2-1,2-2,2-3: Semiconductor laser device 3: Silicon substrate (semiconductor substrate) 4,4 ': Microprojection 5: P-type diffusion layer (light receiving region) 6: Al electrode 7: Photodetectors 8, 8 ': Module for multi-wavelength light source pickup 9: Hologram element 11: SOI substrate 11a: Substrate silicon layer 11b: Silicon oxide film layer 11c: Active silicon layer 12: Transparent substrate 13: Resist pattern (mask)

Claims (8)

[Claims] 1. A multi-wavelength light source pickup module used in an optical pickup device using a plurality of light sources having different wavelengths, comprising: a semiconductor substrate; and a first laser beam emitted on the semiconductor substrate and emitting a first laser beam. A semiconductor laser device, a second semiconductor laser device disposed on the semiconductor substrate and emitting a second laser beam having a different wavelength from the first semiconductor laser device, and the first semiconductor laser device formed on the semiconductor substrate. A multi-wavelength light source pickup, comprising: a microprojection having a flat inclined surface for reflecting a second laser beam in a predetermined direction; and a photodetector formed on the semiconductor substrate. module. 2. The module for a multi-wavelength light source pickup according to claim 1, wherein said minute projections are formed by etching, and KOH and (CH ₃ ) ₄ NOH are formed when said minute projections are etched.
A multi-wavelength light source pickup module characterized in that is used as an etchant. 3. The multi-wavelength light source pickup module according to claim 1, wherein an SOI substrate is used as the semiconductor substrate, and the SOI substrate is anodically bonded to a glass substrate. Module. 4. The module for a multi-wavelength light source pickup according to claim 1, wherein a metal film or a retardation film is deposited on the minute projections. . 5. The multi-wavelength light source pickup module according to claim 1, further comprising a plurality of semiconductor laser elements having different wavelengths. 6. The multi-wavelength light source pickup module according to claim 1, further comprising a plurality of semiconductor laser elements having different wavelengths, wherein a distance between each semiconductor laser element and the minute projection is different from each other. A multi-wavelength light source pickup module, which is arranged so as to be shifted by a predetermined distance for each semiconductor laser element. 7. The multi-wavelength light source pickup module according to claim 1, wherein a minute projection having a length different from one side and another side is formed on the semiconductor substrate. Features Multi-wavelength light source pickup module. 8. An optical pickup device for recording, reproducing or erasing information by condensing a laser beam from a light source on an optical recording medium, comprising a module in which a plurality of light sources having different wavelengths and a photodetector are integrated. An optical pickup device using the multi-wavelength light source pickup module according to any one of claims 1 to 7 as the module.