JP2009229809A - Mirror, method for manufacturing mirror, and optical pickup device using mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micromirror wherein an inclined angle and flatness of a reflection plane can be made in a prescribed range and productivity can be enhanced more than conventional one, to provide a method for manufacturing the micromirror and to provide an optical pickup device using the micromirror. <P>SOLUTION: A micromirror 25 has a surface (111) to be a crystal plane of a single crystal silicon as a reflection surface A25. Micromirrors 35 and 45 have flattened layers 30 and 40 formed on the reflection surface and having surfaces having flatness lower than that of the reflection surface and a reflection film 20 formed on the surfaces of the flattened layers. A micromirror 85 has an alignment pattern 82 formed on a surface different from the reflection surface. In the optical pickup device 100, any of the micromirrors 25, 35, 45 and 85 is used. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mirror, a mirror manufacturing method, and an optical pickup device using the mirror, and in particular, a micromirror using a wafer made of single crystal silicon as a mirror base material, a micromirror manufacturing method, and a micromirror. The present invention relates to an optical pickup device using a mirror.

Optical discs such as CD (Compact Disc) and DVD (Digital Versatile Disc) are widely used as information recording media. As an optical pickup device for reproducing information recorded on the optical disk, a semiconductor laser element that emits laser light, a micromirror that reflects the emitted laser light toward the optical disk (simply called “mirror”). In some cases, an optical integrated device including a substrate having a light receiving region in which the semiconductor laser element and the micromirror are fixed and receiving reflected light from the optical disk is widely used.
An example of an optical pickup apparatus using such an optical integrated device is disclosed in Patent Document 1.
JP 11-296873 A

Here, a general manufacturing method of the micromirror used in the optical pickup device as described above will be described with reference to FIG.
FIG. 14 is a perspective view for explaining a conventional method of manufacturing a general micromirror, wherein (a) to (d) in FIG. 14 respectively show processes for manufacturing the micromirror.

First, as shown in FIG. 14A, a plurality of glass bars 302 are formed by cutting a glass plate 300 which is a base material of a micromirror 320 described later at a predetermined interval (for example, 0.5 mm).
Next, as shown in FIG. 14B, the edge of the glass bar 302 is polished to form an inclined surface 306 having an inclination angle θ306 of 45 ° with respect to the bottom surface B302 on the glass bar 302.
Thereafter, as shown in FIG. 14C, a reflective film 308 made of a metal film or a multilayer dielectric film is formed on at least the inclined surface 306.
Further, as shown in FIG. 14 (d), by cutting the glass bar 302 that has undergone the above-described steps at a predetermined interval, the micro mirror 320 having the inclined surface 306 on which the reflective film 308 is formed as the reflective surface A320 is formed. Get multiple.

  The reflection surface A320 of the micromirror 320 is a surface that reflects the laser light emitted from the semiconductor laser element toward the optical disk in the optical pickup device.

  By the way, due to the requirement of the optical axis accuracy of the optical pickup device, the inclination angle θ306 of the reflection surface 310 of the micromirror 320 needs to be within 45 ° ± 0.1 °, and the reflection surface A320 is optical It is necessary to have a wavefront aberration of 8 / λ (λ is the wavelength of the laser beam), in other words, a flatness of 100 nm or less, and more preferably 50 nm or less.

However, in the above-described micromirror and the manufacturing method thereof, the glass bar 302 formed in the process of manufacturing the micromirror 320 has a very long and narrow shape, so that the polishing process is difficult and the inclination angle and flatness of the reflecting surface 310 are difficult. Is difficult to machine with the above accuracy.
In an optical pickup device, if the tilt angle or flatness of the reflection surface of the micromirror is poor, the optical axis of the laser beam is shifted or scattered, so the laser beam is irradiated at a predetermined position on the optical disk with a predetermined intensity. Can not do. For this reason, the signal strength is weakened, which causes a reduction in the SN ratio.
Further, since the polishing process is performed for each glass bar 302, productivity is poor, and improvement thereof is desired.

  Therefore, the problem to be solved by the present invention is that the tilt angle and flatness of the reflecting surface can be within a predetermined range, and the productivity can be improved as compared with the conventional one, An object of the present invention is to provide an optical pickup device using a micromirror.

In order to solve the above problems, each invention of the present application has the following means.
1) A mirror (25) having a (111) plane which is a crystal plane of single crystal silicon as a reflection plane (A25).
2) a planarization layer (30, 40) formed on the reflection surface and having a surface with a lower flatness than the reflection surface; and a reflection film (20) formed on the surface of the planarization layer; The mirror (35, 45) according to 1).
3) The mirror (85) according to 1) or 2), wherein the mirror (85) has another surface different from the reflecting surface, and an alignment pattern (82) is formed on the other surface. is there.
4) The ingot (1) made of single crystal silicon is cut at a predetermined interval at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane, which is the crystal plane. A first cutting step for producing a wafer (10), and after the first cutting step, the silicon wafer is partially anisotropically etched to form a crystal plane of the single crystal silicon on the silicon wafer. A V-groove portion forming step for forming a plurality of V-groove portions (18) having a (111) surface as an inner surface (A18) in a stripe shape, and a reflective film (20) on the (111) surface after the V-groove portion forming step. A reflective film forming step to be formed, and after the reflective film forming step, the silicon wafer is cut to produce a mirror (25) having the (111) surface on which the reflective film is formed as a reflective surface (A25). Second cutting And extent, a method for producing a mirror having a.
5) The method for producing a mirror according to 4), wherein the procedure includes a step of polishing or electric field etching the (111) plane between the V-groove forming step and the reflective film forming step. .
6) The ingot (1) made of single crystal silicon is cut at a predetermined interval at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane which is the crystal plane. A first cutting step for producing a wafer (10), and after the first cutting step, the silicon wafer is partially anisotropically etched to form a crystal plane of the single crystal silicon on the silicon wafer. A V-groove portion (18) having a certain (111) surface as an inner surface (A18) and forming a plurality of V-groove portions (18) in a stripe shape, and after the V-groove portion forming step, the (111) surface on the (111) surface A planarization layer forming step for forming a planarization layer (30, 40) having a flatness smaller than the flatness of the surface, and a reflective film (20) is formed on the planarization layer after the planarization layer formation step. Reflective film forming process and before After the reflective film forming step, the silicon wafer is cut to produce mirrors (35, 45) in which the (111) surface on which the planarizing layer and the reflective film are formed is the reflective surface (A35, A45). And a second cutting step.
7) The ingot (1) made of single crystal silicon is cut at a predetermined interval at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane, which is the crystal plane. A first cutting step for producing a wafer (10), and after the first cutting step, the silicon wafer is partially anisotropically etched to form a crystal plane of the single crystal silicon on the silicon wafer. A plurality of V-groove portions (18) having a (111) surface as an inner surface (A18) are formed in a stripe shape, and a concave evaluation pattern having an opening wider than the V-groove portion with the (111) surface as an inner surface ( 72) to form the V-groove portion and the evaluation pattern forming step, and after the V-groove portion and the evaluation pattern forming step, by evaluating the (111) plane of the evaluation pattern, 1) an evaluation process for indirectly evaluating the surface, a reflective film forming process for forming a reflective film (20) on the (111) plane of the V-groove portion after the evaluation process, and the silicon film after the reflective film forming process A second cutting step of cutting a wafer to produce a mirror (75) having the (111) surface of the V-groove portion on which the reflective film is formed as a reflective surface (A75). is there.
8) The ingot (1) made of single crystal silicon is cut at a predetermined interval at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane as the crystal plane. A first cutting step for producing a wafer (10), and after the first cutting step, the silicon wafer is partially anisotropically etched to form a crystal plane of the single crystal silicon on the silicon wafer. A plurality of V-groove portions (18) having a certain (111) surface as an inner surface (A18) are formed in stripes, and a V-groove portion that forms a concave alignment pattern (82) having an opening narrower than the V-groove portion. And a pattern forming process for alignment, a reflective film forming process for forming a reflective film (20) on the (111) surface after the V groove and alignment pattern forming process, and the reflective film forming process Then, the silicon wafer is cut to produce a mirror (85) having the reflecting pattern (A85) as the reflecting surface (A85) having the alignment pattern and the reflecting film formed thereon. The manufacturing method of the mirror which has these.
9) The laser beam (L) is emitted toward the optical disc (D) on which predetermined information is recorded, and the laser beam (La) reflected by the optical disc is received and subjected to photoelectric conversion, whereby the information is converted. In a reproducing optical pickup device, a semiconductor laser element (140) that emits the laser light, and a mirror (A150) that reflects the laser light emitted from the semiconductor laser element toward the optical disk ( 150) and a light receiving unit (121) that receives and laser-converts the laser beam reflected by the optical disc, and the mirror is the mirror according to any one of 1) to 3). An optical pickup device (100) is characterized.
10) The laser beam (L) is emitted toward the optical disc (D) on which predetermined information is recorded, and the laser beam (La) reflected by the optical disc is received and subjected to photoelectric conversion to thereby convert the information. In a reproducing optical pickup device, a semiconductor laser element (140) that emits the laser light, and a mirror (A150) that reflects the laser light emitted from the semiconductor laser element toward the optical disk ( 150) and a light receiving unit (121) that receives and photoelectrically converts the laser beam reflected by the optical disk, and the mirror is manufactured by the mirror manufacturing method according to any one of 4) to 8). An optical pickup device (100) manufactured.

  According to the present invention, the inclination angle and flatness of the reflecting surface of a micromirror (sometimes simply referred to as “mirror”) can be within a predetermined range, and a micromirror can be manufactured with higher productivity than in the past. There is an effect.

Embodiments of the present invention will be described with reference to FIGS. 1 to 12 according to first to sixth embodiments which are preferred examples.
The first to fifth embodiments are embodiments of a micromirror (sometimes simply referred to as “mirror”) and a method for manufacturing the same according to the present invention, and the sixth embodiment is the first to fifth embodiments. It is an Example of the optical pick-up apparatus using either of the micromirrors of 6 Example.

<First embodiment>
A first embodiment of a micromirror and a manufacturing method thereof according to the present invention will be described with reference to FIGS.
1 to 6 are perspective views for explaining the micromirror of the first embodiment and the manufacturing method thereof, and correspond to the steps A1 to A6, which are processes of manufacturing the micromirror of the first embodiment, respectively. Is.
2, 3, 4 (a), 4 (c), 5, and 6 are enlarged regions of the V-groove portion or the V-groove portion of the Si wafer 10 of FIG. 1. FIG. 4B shows the entire Si wafer 10.

[Step A1] (see FIG. 1)
First, the ingot 1 made of a single crystal of Si (silicon) is cut at a predetermined interval at an angle inclined by 9.7 ° in the (110) plane direction with respect to the (100) plane which is the crystal plane ( A plurality of Si wafers 10 are obtained by slicing.
In the ingot 1, the (100) plane is a plane orthogonal to the reference plane 2 that becomes the orientation flat A 10 of the Si wafer 10, and the (110) plane is a plane parallel to the reference plane 2.
In general, the processing accuracy when slicing an ingot made of a single crystal of Si is within a range of ± 1/60 ° (plus or minus 1/60 °) with respect to a target cutting angle, and is very high. A Si wafer can be produced with processing accuracy.
In the first embodiment, the thickness of the polished Si wafer 10 is 0.5 mm.

[Step A2] (see FIG. 2)
After polishing at least one surface side of the Si wafer 10, a film 12 having corrosion resistance against a strong alkaline etching solution is formed on this surface.
As the film 12, a SiO ₂ (silicon dioxide) film or a SiN (silicon nitride) film can be used, and these films can be formed using a known semiconductor process.
If the thickness of the film 12 is too thin, the above-mentioned corrosion resistance is deteriorated. If it is too thick, the film formation time becomes long and the productivity is deteriorated. Therefore, it is desirable that the film 12 be in the range of 0.1 μm to 3 μm.

[Step A3] (See FIG. 3)
Using the photolithography method, a plurality of openings 14 having a predetermined width W14 extending in a direction orthogonal to the orientation flat A10 (see FIG. 1) are formed in a stripe shape in the film 12. The film 12 having the opening 14 becomes an etching mask 16 for anisotropic etching performed in the A4 process described later.
FIG. 3 shows one of the plurality of openings 14 formed.
In the first embodiment, the width W14 of the opening 14 is 0.6 mm.

[Step A4] (see FIG. 4)
First, as shown in FIG. 4A, the Si wafer 10 in the region exposed by the opening 14 is anisotropically etched with a strong alkaline etching solution, whereby the V-groove 18 is formed in a stripe shape on the Si wafer 10. A plurality are formed.
As the strongly alkaline etching solution, KOH (potassium hydroxide) solution, ethylenediamine solution, TMAH (tetramethylammonium hydroxide) solution, etc. can be used, and a surfactant or alcohol is added to these solutions. Can be used.
FIG. 4A shows one of the plurality of V-groove portions 18 formed.

  Thereafter, as shown in FIGS. 4B and 4C, the etching mask 16 is removed.

Here, the V-groove portion 18 will be described in detail with reference to FIG.
As shown in FIG. 4C, one inner surface A18 of the V-groove 18 is a (111) plane that is a crystal plane of the Si wafer 10, and the other inner surface B18 is a (−111) plane.
The (111) plane is a plane inclined by 54.7 ° with respect to the (100) plane, and the back surface (front surface) of the Si wafer 10 is a plane inclined by 9.7 ° with respect to the (100) plane. The (111) plane is an inclined surface having an inclination angle θa of 45 ° with respect to the back surface (front surface) of the Si wafer 10.
On the other hand, the (−111) plane is an inclined surface inclined by 64.4 ° with respect to the back surface (front surface) of the Si wafer 10.

  Single-crystal Si has the property that the etching rate with a strong alkaline etching solution varies depending on the crystal plane. In addition, the (111) plane, which is the crystal plane of single crystal Si, has a slower etching rate than other crystal planes. Therefore, by performing the anisotropic etching, as shown in FIG. A V-groove having the (111) plane as an inner surface is formed.

  The (111) plane that is one inner surface A18 of the V-groove portion 18 described above is a surface that becomes a reflection surface A25 of the micromirror 25 described later.

[Step A5] (See FIG. 5)
The reflective film 20 is formed on the Si wafer 10 so as to cover at least the (111) surface of the V groove 18.
As the reflective film 20, a film mainly composed of a metal such as Au (gold), Al (aluminum), Ag (silver) or an alloy thereof (for example, Ag-Pd (palladium) alloy) or a multilayer dielectric film is used. These films can be formed using a known method such as vapor deposition, sputtering, or plating.

[Step A6] (see FIG. 6)
By cutting the Si wafer 10 into a predetermined size by dicing or the like, a plurality of micromirrors 25 having the (111) surface covered with the reflective film 20 as the reflective surface A25 are produced.
The reflection surface A25 of the micromirror 25 is a surface that reflects laser light L emitted from a semiconductor laser element 140 of the optical pickup device 100 described later toward the optical disc D.

  According to the micromirror of the first embodiment and the manufacturing method thereof, in particular, a Si wafer is produced by slicing an ingot made of a single crystal of Si with high processing accuracy, and the (111) plane which is the crystal plane of this Si wafer. Is used as the reflecting surface, the inclination angle of the reflecting surface in the micromirror can be within 45 ° ± 0.1 °.

  In addition, according to the micromirror of the first embodiment and the manufacturing method thereof, in particular, since the (111) plane which is the crystal plane of the Si wafer is used as the reflecting surface, the flatness of the reflecting surface can be made 100 nm or less. .

  In addition, according to the micromirror of the first embodiment and the manufacturing method thereof, in particular, since a plurality of V-groove parts (reflective surfaces) are formed at a time on the Si wafer, productivity can be improved as compared with the prior art.

<Second embodiment>
A second embodiment of the micromirror and the manufacturing method thereof according to the present invention will be described with reference to FIGS.
FIG. 7 is a view for explaining the micromirror of the second embodiment and the manufacturing method thereof, and (a) to (d) in FIG. 7 show the steps of manufacturing the micromirror of the second embodiment, respectively. (A-1), (b-1), (c-1), and (d) are perspective views, and (a-2), (b-2), and (c-2) are It is typical sectional drawing.
FIG. 8 is a view for explaining the micromirror of the second embodiment and the manufacturing method thereof, and FIGS. 8A to 8C show the process of manufacturing the micromirror of the second embodiment, respectively. FIG. 2 is a perspective view, and (a-2) and (b-2) are schematic cross-sectional views.

The second embodiment forms a flattening layer on the (111) surface of the V-groove for the purpose of further improving the flatness of the reflection surface of the micromirror compared to the first embodiment described above. The point that the reflective film is formed on the layer is different, and the other points are the same as in the first embodiment, and in particular, the planarization layer and the method for forming the same will be described in detail.
The same components as those in the first embodiment will be described with the same reference numerals.

  First, an example in which a BPSG (Boron Phosphorus Silicon Glass) film is used as the planarizing layer will be described with reference to FIG.

  First, as shown in FIG. 7A, the same steps as the steps A1 to A4 of the first embodiment described above are performed to manufacture the Si wafer 10 in which a plurality of V-groove portions 18 are formed in stripes.

Next, as shown in FIG. 7B, a BPSG film 30 is formed on the Si wafer 10 by using, for example, a CVD (Chemical Vapor Deposition) method so as to cover at least the (111) surface of the V-groove portion 18. To do.
Since the BPSG film 30 is formed by reflecting the surface shape of the V-groove portion 18, the flatness of the surface of the BPSG film 30 after film formation is substantially the same as the flatness of the (111) plane of the V-groove portion 18. is there.
Further, if the thickness of the BPSG film 30 is too thin, the flatness of the reflecting surface is not improved by the heat treatment described later, and if it is too thick, the productivity is deteriorated. Therefore, the thickness is within the range of 0.1 μm to 1 μm. It is desirable.

  Further, as shown in FIG. 7C, the BPSG film 30 flows by performing a heat treatment for heating the Si wafer 10 to a temperature higher than the softening point temperature of the BPSG film 30 (for example, a temperature around 1000 ° C.). Therefore, the surface of the BPSG film 30 becomes smooth and its flatness is improved.

Thereafter, the same steps as the steps A5 and A6 of the first embodiment described above are performed to obtain a plurality of micromirrors 35 shown in FIG.
In the micromirror 35, the (111) surface (inner surface A18) covered with the BPSG film 30 that is a planarization layer and the reflective film 20 is a laser beam L emitted from a semiconductor laser element 140 of the optical pickup device 100 described later. Becomes a reflection surface A35 that reflects the light toward the optical disk D.

  Next, an example using an SOG (Spin On Glass) film as the planarizing layer will be described with reference to FIG.

  First, as shown in FIG. 8A, the same steps as the steps A1 to A4 of the first embodiment described above are performed to manufacture the Si wafer 10 in which a plurality of V-groove portions 18 are formed in a stripe shape.

Next, as shown in FIG. 8B, liquid SOG is applied to the Si wafer 10 by using a spin coating method, and further heated and dried, so that the (111) surface (inner surface A18) of the V groove 18 is obtained. SOG film 40 is formed.
The surface of the SOG film 40 is a smooth and flat surface that does not reflect the surface shape of the V-groove portion 18.

Thereafter, the same steps as the steps A5 and A6 of the first embodiment described above are performed to obtain a plurality of micromirrors 45 shown in FIG.
In the micromirror 45, the (111) surface covered with the SOG film 40, which is a flattening layer, and the reflective film 20 causes laser light L emitted from a semiconductor laser element 140 of the optical pickup device 100 described later to be applied to the optical disk D. It becomes the reflective surface A45 which reflects toward.

  According to the micromirror of the second embodiment and the manufacturing method thereof, in particular, a smoothing layer is formed on the crystal plane {(111) plane} of the Si wafer to be a reflecting surface, and the reflecting film is formed on the smoothing layer. Since the film is formed, the flatness of the reflecting surface can be further improved as compared with the first embodiment. For example, the flatness of the reflecting surface can be 50 nm or less.

<Third embodiment>
A third embodiment of the micromirror and the manufacturing method thereof according to the present invention will be described with reference to FIG.
FIG. 9 is a perspective view for explaining the micromirror according to the third embodiment and the manufacturing method thereof.

The third embodiment differs from the first embodiment described above in that the (111) surface of the V-groove is polished or electrolytically etched for the purpose of further improving the flatness of the reflecting surface of the micromirror. Is the same as in the first embodiment, and in particular, the polishing method and electrolytic etching method for the (111) plane of the V-groove will be described in detail.
The same components as those in the first embodiment will be described with the same reference numerals.

  First, a method for polishing the (111) surface of the V-groove portion serving as a reflection surface will be described with reference to FIGS.

Steps A1 to A4 of the first embodiment described above are performed to produce a Si wafer 10 in which a plurality of V-groove portions 18 are formed in stripes {see FIGS. 4B and 4C}.
Next, as shown in FIG. 9A, by supplying the polishing liquid 51 from the nozzle 50 to the surface of the Si wafer 10 and reciprocating along the surface of the Si wafer 10 while rotating the brush 52, The inner surface of the V groove 18 is polished. The Si wafer 10 may be reciprocated while rotating the brush 52.
By this polishing, the flatness of the (111) plane of the V-groove portion 18 serving as a reflective surface is improved.

  As the polishing liquid 51, a polishing liquid in which abrasive grains mainly containing silica, diamond, alumina, BC (Boron Carbide), cerium oxide, iron oxide or the like and having a particle diameter of 0.3 μm or less are dispersed in an alkaline solution is used. It is preferable.

Thereafter, the same steps as the steps A5 and A6 of the first embodiment described above are performed to obtain a plurality of micromirrors 55 shown in FIG. 9B.
In the micromirror 55, the flatness is improved by the polishing and the (111) surface covered with the reflective film 20 directs the laser light L emitted from the semiconductor laser element 140 of the optical pickup device 100 described later toward the optical disk D. The reflection surface A55 is reflected.

  Next, a method for electrolytically etching the (111) plane of the V-groove portion that will be the reflective surface will be described with reference to FIG.

First, the same steps as the steps A1 to A4 of the first embodiment described above are performed to produce the Si wafer 10 in which a plurality of V-groove portions 18 are formed in stripes {see FIGS. 4B and 4C. }.
Next, by subjecting the Si wafer 10 to an electrolytic etching process, the electric field is particularly concentrated on the convex portion of the inner surface {(111) surface} of the V-groove portion 18, and the convex portion is actively etched. The flatness of the (111) plane of the V-groove 18 that becomes the plane is improved.

Thereafter, the same steps as the steps A5 and A6 of the first embodiment described above are performed to obtain a plurality of micromirrors 65 shown in FIG. 9C.
In the micromirror 65, the (111) surface whose flatness is improved by the electrolytic etching and is covered with the reflective film 20 directs the laser light L emitted from the semiconductor laser element 140 of the optical pickup device 100 described later to the optical disk D. The reflection surface A65 is reflected.

  According to the micromirror of the third embodiment and the manufacturing method thereof, in particular, by performing polishing or electrolytic etching on the (111) plane which is the crystal plane of the Si wafer that becomes the reflection plane, the reflection plane is more than that of the first embodiment. The flatness of can be further improved. For example, the flatness of the reflecting surface can be 50 nm or less.

<Fourth embodiment>
A fourth embodiment of the micromirror and the manufacturing method thereof according to the present invention will be described with reference to FIG.
FIGS. 10A and 10B are views for explaining the micromirror of the fourth embodiment and the method for manufacturing the micromirror. FIGS. 10A and 10B are plan views, and FIGS. 10C and 10D are V-groove portions 18 of FIG. And the expanded sectional view of the pattern 70 for evaluation, (e) is a perspective view of the micromirror of 4th Example.

The fourth example forms an evaluation pattern together with the V groove on the Si wafer as compared with the first to third examples described above, and the flatness and inclination angle of the (111) plane in the evaluation pattern are set. The purpose of the inspection is to indirectly inspect the flatness and the inclination angle of the (111) surface of the V-groove as a reflection surface, and otherwise the first embodiment to the third embodiment. Since these are the same, the evaluation pattern and its formation method and inspection method will be described in detail.
In addition, the same code | symbol is attached | subjected and demonstrated to the same component as 1st Example-3rd Example.

  First, the same steps as the first step and the second step of the first embodiment are performed to produce a Si wafer 10 on which a film 12 having corrosion resistance against a strong alkaline etching solution is formed on one side (FIG. 2).

  Next, as shown in FIG. 10A, using the photolithography method as in the third step of the first embodiment, the film 12 has a predetermined width W14 extending in a direction orthogonal to the orientation flat A10. A plurality of openings 14 having a stripe shape are formed, and a predetermined region {in FIG. 10 (a), as an example, shown as four regions separated from each other in the vicinity of the wafer periphery} than the width W14. For example, another rectangular opening 70 having a wide width W70 is formed. The film 12 having the openings 14 and 70 becomes an etching mask 71 for anisotropic etching described later.

  Thereafter, as shown in FIG. 10B, the Si wafer 10 in the region exposed by the openings 14 and 70 is anisotropically etched with a strong alkaline etchant similar to that of the first embodiment, thereby obtaining Si. A plurality of V-groove portions 18 are formed in stripes on the wafer 10, and an evaluation pattern 72 having a concave truncated pyramid shape whose opening is wider than the bottom surface is formed.

  Thereafter, the etching mask 71 is removed.

Normally, when the Si wafer 10 is anisotropically etched, the Si wafer 10 is etched along its crystal plane, so that the cross-sectional shape of the etched portion is initially trapezoidal, but the etching proceeds. The width of the bottom surface becomes narrower and eventually becomes V-shaped.
Therefore, since the evaluation pattern 72 is wider than the width of the V-groove portion 18, the anisotropic etching is finished when the V-groove portion 18 is formed, thereby forming a truncated pyramid shape {FIG. ) To (d)}.

By the way, in order to observe the (111) plane of the V-groove 18 serving as a reflection surface with an optical microscope, measure the flatness and surface roughness with an optical interference surface roughness meter, and measure the tilt angle θa. In general, the (111) plane must be observed and measured from the vertical direction.
However, as shown in FIG. 10 (c), the V-groove 18 has a narrow opening width. Therefore, when the (111) plane, which is the inner surface, is observed and measured from the vertical direction, the other (−111) plane side is used. It is difficult to observe and measure accurately because the edge of the wall interferes.

On the other hand, as shown in FIG. 10 (d), the evaluation pattern 72 has a sufficiently wide opening width with respect to the V-groove portion 18, so that the (111) surface, which is the inner surface, is in a non-destructive state. It is possible to observe with an optical microscope from the vertical direction, and to measure the flatness and surface roughness with an optical interference surface roughness meter.
Moreover, since the evaluation pattern 72 has a bottom surface parallel to the surface of the Si wafer 10, the depth of the evaluation pattern 72 and the width of the inclined region can be accurately measured with an optical interference surface roughness meter. The inclination angle θb of the (111) plane of the evaluation pattern 72 can be calculated from these depths and widths. Further, the inclination angle θb of the (111) plane of the evaluation pattern 72 is equal to the inclination angle θa of the (111) plane of the V groove 18.
That is, by calculating the inclination angle θb of the (111) plane of the evaluation pattern 72, the inclination angle θa of the (111) plane of the V-groove portion 18 can be obtained indirectly.

Then, the (111) surface of the evaluation pattern 72 is observed with an optical microscope, and the flatness and surface roughness of the (111) surface are measured with an optical interference surface roughness meter. The inclination angle θb is calculated, and it is determined (inspected) whether or not these observation results, measurement results, and calculation results satisfy a predetermined standard.
If each standard is satisfied, it is determined to be OK, and the process proceeds to the next process. If any of the standards is not satisfied, it is determined to be NG, and processing is performed based on a predetermined procedure such as disposal. .

  Thereafter, the steps A5 and A6 of the first embodiment, the subsequent steps including the planarization layer forming step of the second embodiment, or the subsequent steps including the polishing step or the electrolytic etching step of the third embodiment, A plurality of micromirrors are manufactured by performing the same process as in step (b).

The micromirror of the fourth embodiment has the same configuration as the micromirror 25 of the first embodiment if the same process as that of the first embodiment is performed, and the micromirror of the second embodiment if the same process as that of the second embodiment is performed. The same configuration as that of the micromirrors 35 and 45, and the same configuration as the micromirrors 55 and 65 of the third embodiment if the same process as that of the third embodiment is performed. Reference numeral 75 is attached.
FIG. 10E shows, as an example, a micromirror manufactured by performing the same process as in the first embodiment.

  As shown in FIG. 10 (e), in the micromirror 75, the (111) surface on which the reflection film 20 is formed has a laser beam L emitted from a semiconductor laser element 140 of the optical pickup device 100 to be described later applied to the optical disk D. It becomes the reflective surface A75 which reflects toward.

According to the micromirror of the fourth embodiment and the method of manufacturing the micromirror, in particular, an evaluation pattern having a width wider than the width of the V-groove is provided together with the V-groove on the Si wafer in the process of manufacturing the micromirror. By evaluating the (111) plane of the pattern for use, it is possible to indirectly evaluate the (111) plane of the V-groove portion that becomes the reflective surface of the micromirror.
Thereby, since the reflective surface can be evaluated in advance in the process of manufacturing the micromirror, the micromirror can be manufactured more efficiently than the first to third embodiments.

<Fifth embodiment>
A fifth embodiment of the micromirror and the manufacturing method thereof according to the present invention will be described with reference to FIG.
FIG. 11 is a perspective view for explaining a micromirror according to a fifth embodiment and a method for manufacturing the micromirror, and FIGS. 11A to 11C show processes for manufacturing the micromirror according to the fifth embodiment. It is shown.

In the fifth embodiment, in contrast to the first to third embodiments described above, the alignment pattern is formed on the Si wafer together with the V-groove, thereby recognizing the alignment pattern and using the micromirror. It is intended to be aligned and mounted on a semiconductor substrate, which will be described later, and is otherwise the same as the first to third embodiments. The formation method will be described in detail.
In addition, the same code | symbol is attached | subjected and demonstrated to the same component as 1st Example-3rd Example.

The same steps as the first step and the second step of the first embodiment are performed to produce a Si wafer 10 on which a film 12 having corrosion resistance against a strong alkaline etching solution is formed on one side (see FIG. 2). ).
Next, as shown in FIG. 11A, using the photolithography method in the same manner as the third step of the first embodiment, the film 12 is extended in a direction orthogonal to the orientation flat A10 and has a predetermined width W14. A plurality of openings 14 having stripes are formed, and another opening 80 having a cross shape having a width W80 smaller than the width W14 is formed so as to correspond to each of the plurality of micromirrors to be formed. The film 12 having the openings 14 and 80 becomes an etching mask 81 for anisotropic etching described later.

  Thereafter, as shown in FIG. 11B, the Si wafer 10 in the region exposed by the openings 14 and 80 is anisotropically etched with a strong alkaline etching solution such as a KOH (potassium hydroxide) solution or an ethylenediamine solution. Thus, a plurality of V-groove portions 18 are formed in a stripe shape on the Si wafer 10, and the alignment pattern 82 having a V-shaped cross-sectional shape is formed in a concave shape with respect to the surface of the Si wafer 10.

As described above, normally, when the Si wafer 10 is anisotropically etched, the Si wafer 10 is etched along the crystal plane and finally becomes V-shaped. Since the etching rate becomes extremely slow, the shape and the etching depth hardly change.
Therefore, since the alignment pattern 82 is narrower than the V-groove portion 18 because the width is narrower than the V-groove portion 18, the alignment pattern 82 reduces the mechanical strength of the micromirror. There is no problem.

  Next, after removing the etching mask 81, as shown in FIG. 11C, the subsequent steps including the A5 step and the A6 step of the first embodiment, the planarization layer forming step of the second embodiment, or A plurality of micromirrors are obtained by performing the same steps as the subsequent steps including the polishing step or the electrolytic etching step of the third embodiment.

The micromirror of the fifth embodiment has a configuration in which the alignment pattern 82 is formed on the micromirror 25 of the first embodiment if the same process as that of the first embodiment is performed, and the same process as that of the second embodiment. If the step is performed, the alignment pattern 82 is formed on the micromirrors 35 and 45 of the second embodiment. If the same process as the third embodiment is performed, the micromirrors 55 and 65 of the third embodiment are positioned. The alignment pattern 82 is formed. Here, these are collectively referred to as a micromirror 85 and a reference numeral.
FIG. 11C shows, as an example, a micromirror manufactured by performing the same process as in the first embodiment.

  In the micromirror 85, the (111) surface on which the reflective film 20 is formed becomes a reflective surface A85 that reflects laser light L emitted from a semiconductor laser element 140 of the optical pickup device 100 described later toward the optical disc D.

By the way, the micromirror obtained by cutting the Si wafer may cause burrs on the cut surface.
In the process of manufacturing an optical pickup device, when a micromirror is aligned and mounted on a semiconductor substrate, if there is a burr on the end surface (cut surface) of the micromirror, the alignment accuracy deteriorates and the micromirror is mounted on the semiconductor substrate. It becomes difficult to mount it accurately at a predetermined position above.
Therefore, in the fifth embodiment, by forming the alignment pattern 82 on the micromirror, even if burrs occur on the end face (cut surface) of the micromirror, the alignment pattern 82 is recognized and the micromirror is recognized. Since the mirror and the semiconductor substrate are aligned, the micromirror can be accurately mounted on the semiconductor substrate.

  According to the micromirror of the fifth embodiment and its manufacturing method, in particular, an alignment pattern having a width narrower than the width of the V-groove is provided along with the V-groove on the Si wafer in the process of manufacturing the micromirror. By recognizing the alignment pattern and aligning the micromirror with the semiconductor substrate, the micromirror can be mounted at a predetermined position on the semiconductor substrate with high precision even when there is a burr on the end face of the micromirror. be able to.

<Sixth embodiment>
An optical pickup apparatus according to an embodiment of the present invention will be described as a sixth embodiment with reference to FIG.
FIG. 12 is a perspective view for explaining an embodiment of the optical pickup device according to the present invention.

  First, the configuration of the optical pickup device 100 will be described.

  As shown in FIG. 12, the optical pickup device 100 mainly includes an optical integrated device 110, a hologram element 170, and a lens 180.

  The optical integrated device 110 mainly includes a semiconductor substrate 120, a submount 130 mounted on the semiconductor substrate 120, a semiconductor laser element 140 mounted on the submount 130 and emitting laser light L, and the semiconductor substrate 120. And a micromirror 150 having a reflecting surface A150 that reflects the laser beam L emitted from the semiconductor laser element 140 and reflected toward the optical disc D on which predetermined information is recorded.

The semiconductor substrate 120 mainly receives a reflected light La from the optical disc D and photoelectrically converts it into an electrical signal, and a terminal portion 122 for outputting the electrical signal photoelectrically converted by the light receiving unit 121 to the outside. , And is configured.
The light receiving unit 121 and the semiconductor laser element 140 are electrically connected to the terminal unit 122 through wiring (not shown).

  As the micromirror 150, any one of the micromirrors 25, 35, 45, 55, 65, 75, and 85 of the first to fifth embodiments described above can be used. The reflection surface A150 at this time is the reflection surfaces A25, A35, A45, A55, A65, A75, and A85 of the first to fifth embodiments described above.

  The hologram element 170 is an element that transmits the laser light L reflected by the micromirror 150 without being deflected and deflects the reflected light La from the optical disk D toward the light receiving unit 121 of the semiconductor substrate 120.

  The lens 180 is for focusing the laser beam L on an information recording surface (not shown) on which predetermined information is recorded on the optical disc D.

Next, the operation of the above-described optical pickup device 100 will be described.
Here, the case where the micromirror 25 of the first embodiment is used as the micromirror 150 of the optical pickup device 100 will be described as an example.

  By supplying electric power to the semiconductor laser element 140 from the outside via the terminal portion 122, the laser light L is emitted from the semiconductor laser element 140 in parallel with the surface of the semiconductor substrate 120.

  The laser beam L emitted from the semiconductor laser element 140 is reflected by the reflecting surface A25 of the micromirror 25, that is, reflected in the direction perpendicular to the surface of the semiconductor substrate 120.

  The laser beam L reflected by the reflection surface A25 of the micromirror 25 is transmitted without being deflected by the hologram element 170, is condensed by the lens 180, and is focused on the information recording surface of the optical disc D.

  The laser light L focused on the information recording surface of the optical disc D becomes reflected light La having different reflection intensities in accordance with the information signal recorded on the information recording surface.

  The reflected light La passes through the lens 180, is further deflected by the hologram element 170, and enters the light receiving portion 121 of the semiconductor substrate 120.

  The reflected light La incident on the light receiving unit 121 is photoelectrically converted into an electrical signal and output to the outside via the terminal unit 122.

  According to the optical pickup device 100 described above, the reflection surface of the laser light emitted from the semiconductor laser element has an inclination angle of 45 ° ± 0.1 ° and a flatness of 100 nm or less (or 50 nm or less). Therefore, it is possible to prevent the optical axis of the laser light from being shifted or scattered and to irradiate the laser light at a predetermined position on the optical disk with a predetermined intensity. An S / N ratio is obtained.

  The embodiment of the present invention is not limited to the configuration and procedure described above, and it goes without saying that modifications may be made without departing from the scope of the present invention.

For example, in the fifth embodiment, a cross-shaped and concave alignment pattern is provided on the micromirror, but the shape and forming method of the alignment pattern are not limited to this.
For example, a metal film may be formed on a Si wafer, the metal film may be patterned using a photolithography method, and this may be used as an alignment pattern.

  Further, although the alignment pattern is provided on the micromirror in the fifth embodiment, it may be provided on the semiconductor substrate in the sixth embodiment.

A modification of the optical pickup device according to the present invention will be described with reference to FIG.
FIG. 13 is a plan view for explaining a modification of the optical pickup device according to the present invention, and particularly shows a semiconductor substrate in the optical pickup device.
In addition, the same code | symbol is attached | subjected and demonstrated to the same component as 6th Example.

As shown in FIG. 13, the optical pickup device according to the modified example is different from the semiconductor substrate 120 according to the sixth embodiment in that the alignment pattern 221 is formed on the semiconductor substrate 220, and the rest is the same. It is.
The alignment pattern 221 is formed by partially anisotropically etching the semiconductor substrate 220 or by forming a film mainly containing metal or the like on the semiconductor substrate 220 and then using the photolithography method. Can be formed by patterning.

A submount 130 is mounted at a predetermined position of the semiconductor substrate 220.
The region surrounded by the broken line D1 is a region where the micromirror 85 (see FIG. 12) is mounted, and the region surrounded by the broken line D2 is a region where the semiconductor laser element 140 (see FIG. 12) is mounted.

After the pattern 221 for alignment of the semiconductor substrate 220 and the pattern 82 for alignment of the micromirror 85 of the fifth embodiment described above are recognized, and the micromirror 85 and the semiconductor substrate 220 are aligned, By mounting the micromirror 85 on the semiconductor substrate 220, the mounting position accuracy of the micromirror on the semiconductor substrate 220 can be further improved as compared with the sixth embodiment. That is, the micromirror 85 can be more accurately mounted in a desired region (region surrounded by the broken line D1) of the semiconductor substrate 220.
Thereby, the SN ratio can be further improved as compared with the sixth embodiment.

  Further, since the alignment pattern 221 of the semiconductor substrate 220 can be used when the semiconductor laser element 140 is subsequently mounted on the submount 130, the mounting position accuracy of the semiconductor laser element 140 on the semiconductor substrate 220 is improved. It can also be made. That is, the semiconductor laser element 140 can be more accurately mounted in a desired region (region surrounded by the broken line D2) of the submount 130.

In addition, although the evaluation pattern is formed in the fourth embodiment and the alignment pattern is formed in the fifth embodiment, the evaluation pattern and the alignment pattern are formed at the same time together with the V-groove portion. May be.
According to this procedure, the V-groove part, the evaluation pattern, and the alignment pattern can be formed at a time without deteriorating productivity.

  In the first to fifth embodiments, the surface of the V-groove having an inclination angle of 45 ° is the (111) plane, and the surface having the inclination angle of 64.4 ° is the (−111) plane. Since the surface is reversed depending on how it is defined, the surface having the inclination angle of the V groove of 45 ° may be the (111) surface or the (−111) surface. Here, the inclination angle of the V groove is A surface having a 45 ° angle is defined as “(111) surface”.

It is a perspective view for demonstrating 1st Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 1st Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 1st Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 1st Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 1st Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 1st Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 2nd Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 2nd Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating the 3rd Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating the 4th Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating 5th Example of the micromirror which concerns on this invention, and its manufacturing method. It is a perspective view for demonstrating the Example of the optical pick-up apparatus which concerns on this invention. It is a top view for demonstrating the modification of the optical pick-up apparatus which concerns on this invention. It is a perspective view for demonstrating the manufacturing method of a general micromirror.

Explanation of symbols

1_ingot, 2_reference plane, 10_Si wafer, 12_film, 14,70_opening, 16,71,81_etching mask, 18_V groove, 20_reflection film, 25,35,45,55,65,75,85,150_micro Mirror, 30_BPSG film, 40_SOG film, 50_ nozzle, 51_ polishing liquid, 52_ brush, 72_ evaluation pattern, 82_ alignment pattern,
100_ optical pickup device, 110_ optical integrated device, 120_ semiconductor substrate, 121_ light receiving unit, 122_ terminal unit, 130_ submount, 140_ semiconductor laser element, 170_ hologram element, 180_ lens, A10_ orientation flat, W14, W70, W80_ width, A18, B18_ surface, θa_ tilt angle, A25, A35, A45, A55, A65, A75, A85, A150_ reflecting surface, L_ laser light, D_ optical disk, La_ reflected light

Claims (10)

  A mirror having a (111) plane which is a crystal plane of single crystal silicon as a reflection plane. A planarization layer formed on the reflective surface and having a surface with a lower flatness than the reflective surface;
A reflective film formed on the surface of the planarizing layer;
The mirror according to claim 1.   The mirror according to claim 1, wherein the mirror has another surface different from the reflecting surface, and an alignment pattern is formed on the other surface. A silicon wafer is manufactured by cutting an ingot made of single crystal silicon at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane, which is the crystal plane, at a predetermined interval. 1 cutting step;
After the first cutting step, the silicon wafer is partially anisotropically etched to form a V-groove portion having a (111) plane, which is a crystal plane of the single crystal silicon, on the silicon wafer. Forming a plurality of V-groove parts in a shape;
A reflective film forming step of forming a reflective film on the (111) surface after the V groove forming step;
A second cutting step of cutting the silicon wafer after the reflective film forming step to produce a mirror having the (111) surface on which the reflective film is formed as a reflective surface;
A method of manufacturing a mirror having   5. The method of manufacturing a mirror according to claim 4, wherein a step including polishing or electric field etching of the (111) plane is provided between the V groove portion forming step and the reflective film forming step. A silicon wafer is manufactured by cutting an ingot made of single crystal silicon at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane, which is the crystal plane, at a predetermined interval. 1 cutting step;
After the first cutting step, the silicon wafer is partially anisotropically etched to form a V-groove portion having a (111) plane, which is a crystal plane of the single crystal silicon, on the silicon wafer. Forming a plurality of V-groove parts in a shape;
A flattening layer forming step of forming a flattening layer having a flatness smaller than the flatness of the (111) surface on the (111) surface after the V-groove forming step;
A reflective film forming step of forming a reflective film on the flattened layer after the flattened layer forming step;
A second cutting step of cutting the silicon wafer after the reflective film forming step to produce a mirror having the (111) surface on which the planarizing layer and the reflective film are formed as a reflective surface;
A method of manufacturing a mirror having A silicon wafer is manufactured by cutting an ingot made of single crystal silicon at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane, which is the crystal plane, at a predetermined interval. 1 cutting step;
After the first cutting step, the silicon wafer is partially anisotropically etched, so that the V-groove portion having the (111) plane, which is the crystal plane of the single crystal silicon, is striped on the silicon wafer. A V-groove part and an evaluation pattern forming step for forming a concave evaluation pattern having an opening wider than the V-groove part with the (111) surface as an inner surface,
An evaluation step for indirectly evaluating the (111) plane of the V groove portion by evaluating the (111) plane of the evaluation pattern after the V groove portion and the evaluation pattern forming step;
A reflective film forming step of forming a reflective film on the (111) surface of the V-groove after the evaluation step;
A second cutting step of cutting the silicon wafer after the reflecting film forming step to produce a mirror having the (111) surface of the V-groove portion on which the reflecting film is formed as a reflecting surface;
A method of manufacturing a mirror having A silicon wafer is manufactured by cutting an ingot made of single crystal silicon at an angle of 9.7 ° in the direction of the (110) plane with respect to the (100) plane, which is the crystal plane, at a predetermined interval. 1 cutting step;
After the first cutting step, the silicon wafer is partially anisotropically etched, so that the V-groove portion having the (111) plane, which is the crystal plane of the single crystal silicon, is striped on the silicon wafer. And forming a concave alignment pattern having a narrower opening than the V-groove, and a V-groove and alignment pattern forming step,
A reflective film forming step of forming a reflective film on the (111) surface after the V-groove and alignment pattern forming step;
A second cutting step of cutting the silicon wafer after the reflective film forming step to produce a mirror having the alignment pattern and having the (111) surface as a reflective surface on which the reflective film is formed; ,
A method of manufacturing a mirror having In an optical pickup device that emits laser light toward an optical disc on which predetermined information is recorded, receives the laser light reflected by the optical disc, and performs photoelectric conversion to reproduce the information.
A semiconductor laser element for emitting the laser beam;
A mirror having a reflecting surface for reflecting the laser beam emitted from the semiconductor laser element toward the optical disc;
A light receiving unit that receives and laser-converts the laser beam reflected by the optical disc;
Have
The optical pickup device according to claim 1, wherein the mirror is the mirror according to claim 1. In an optical pickup device that emits laser light toward an optical disc on which predetermined information is recorded, receives the laser light reflected by the optical disc, and performs photoelectric conversion to reproduce the information.
A semiconductor laser element for emitting the laser beam;
A mirror having a reflecting surface for reflecting the laser beam emitted from the semiconductor laser element toward the optical disc;
A light receiving unit that receives and laser-converts the laser beam reflected by the optical disc;
Have
The optical mirror device, wherein the mirror is manufactured by the mirror manufacturing method according to any one of claims 4 to 8.

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