JPH0894314A - Optical displacement sensor - Google Patents

Abstract

PURPOSE: To provide an ultra-compact optical displacement sensor where an optical element is accurately and easily positioned. CONSTITUTION: A resin layer 203 of polyimide is provided on the surface of a vertical resonator type surface emitting laser 202. A metal film 204 such as aluminum and an insulation film 205 such as silicon oxide are supported on the resin layer 203. The upper portion of the window part of the vertical resonator type surface emitting laser 202 is hollow and a mirror 206 is displaced according to the outer force when a pressure-sensing element 222 provided on it receives the outer force. A light reception element 207 such as photodiode is mounted to the reverse side of the vertical resonator type surface emitting laser 202 via an n-type electrode 221 and an insulation film 220. The vertical resonator type surface emitting laser 202 and a light reception element 207 are connected to LD and PD power supplies 208 via an electrical wiring 209. The light reception element 207 is connected to an operation device 210.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical displacement sensor including a semiconductor laser, a mirror, a light receiving element and the like.

[0002]

[Prior art]

<Prior art example 1> An example of an optical displacement sensor using a vertical cavity surface emitting laser as a light source and utilizing interference of light is one example of Japanese Patent Application No. 5-198318 filed by the present applicant.
Has been proposed to. The basic structure is shown in FIG.

This optical displacement sensor is shown in FIG.
As shown in FIG.
1 mounted on a silicon substrate 502 and a photodiode 5
05 and the mirror 503 are combined with each other at a position facing each other via the elastic body 504.

When the mirror 503 receives an external force, the elastic body 50
4 is displaced according to the Young's modulus, and a pulse-like waveform due to light interference as shown in FIG. 12B is obtained. Since one cycle of this waveform corresponds to λ / 2 (0.5 μm when λ = 1 μm), the displacement of the mirror 503 can be detected with high accuracy. <Prior art example 2> An optical displacement sensor using a vertical cavity surface emitting laser as a light source, which utilizes that the beam divergence angle of the surface emitting laser can be arbitrarily set,
An example is proposed in Japanese Patent Application No. 6-59339 by the present applicant. The basic structure is shown in FIG.

In this optical displacement sensor, FIG.
As shown in (A), a vertical cavity surface emitting laser 60.
1 is fixed via a heat sink 602 to an inclined portion of a silicon substrate 604 on which a single photodiode 603 is formed. Further, the silicon substrate 604 is fixed to the housing 618 by adhesion or the like via a spacer 605. Support bar 6 passing through guide hole 609 for mirror support bar
The structure including the 08, the external mirror 611 connected thereto, and the target mounting portion 612 is movably supported in the vertical direction by the elastic body 610. The vertical cavity surface emitting laser 601 is connected to an LD drive power source 617 via an electric wiring 607 passing through a through hole 606 and is supplied with a constant current. The photodiode 603 is connected to the light receiving system power source 6 via an electric wiring 614 passing through the through hole 613.
15 and the arithmetic unit 611 and connected to the light receiving system power source 6
A drive current is supplied from 15 and an output signal is output from the arithmetic unit 61.
It is designed to supply one.

The light beam emitted from the vertical cavity surface emitting laser 601 is reflected by the external mirror 611 and is incident on the photodiode 603. Photodiode 6
13 and the distance z between the vertical cavity surface emitting laser 601 and the external mirror 611, for example, as shown in FIG.
There is a relationship shown in (B), and the arithmetic unit 616 obtains the distance z based on the output of the photodiode 603. <Prior Art Example 3> An example of a so-called encoder that uses a semiconductor laser as a light source, intersects light beams emitted from both end faces, arranges a diffraction grating at an optical interference position, and detects the displacement thereof is a special example. It is disclosed in Kaihei 3-291523. The basic structure is shown in FIG.

In this encoder, as shown in FIG. 14A, a semiconductor laser 702 for emitting two light beams in opposite directions, and an optical waveguide 703 for guiding the light beams are provided on a semiconductor substrate 701. A lens 704 that collects the light emitted from the optical waveguide 703 is formed. A diffraction grating 705 is arranged at a position where the two light beams emitted from the lens 704 intersect. Semiconductor substrate 701
On top of that, the photodiode 70
6 is formed.

The two light beams emitted from both end surfaces of the semiconductor laser 702 propagate through the optical waveguide 703 and are condensed on the diffraction grating 705 by the lens 704, and the diffraction grating 7
The lights diffracted at 05 interfere with each other, and FIG.
The photodiode 706 detects the waveform of the intensity change due to the movement of the diffraction grating 705 as shown in FIG.

[0009]

[Problems to be Solved by the Invention]

<Problem of Conventional Example 1> The optical displacement sensor shown in FIG. 12 constitutes a small and highly accurate displacement sensor, but has the following problems.

When the elastic body 504 is mounted on the silicon substrate 502 on which the vertical cavity surface emitting laser 501 is mounted and the mirror 503 is mounted thereon, the surface of the vertical cavity surface emitting laser 501 and the mirror 503 are separated from each other. Since it is necessary to make them parallel with high accuracy, it takes time to position them. Also,
An elastic body 50 is provided outside the vertical cavity surface emitting laser 501.
Since the space for providing 4 is required, the size of the device is increased and the application range of the displacement sensor to the fine region is narrowed.

An object of the present invention is to provide a microminiature optical displacement sensor in which optical elements are easily positioned with high accuracy. <Problem of Conventional Example 2> Further, although the optical displacement sensor shown in FIG. 13 provides a small displacement sensor because of its simple structure, it has the following problems.

When the vertical cavity surface emitting laser 601 is mounted on the silicon substrate 604, it is necessary to align the inclined surface formed on the silicon substrate 604 with high precision, which is troublesome in positioning. Similarly, when the silicon substrate 604 is attached to the housing 618 or when the external mirror 611 and the target attachment portion 612 are installed vertically, it is necessary to perform highly accurate alignment, which requires time and effort for positioning. Also,
Since the housing 618 is provided on the outer side of the silicon substrate 604, the size of the device is increased and the application range of the displacement sensor to the fine area is narrowed.

It is an object of the present invention to provide a microminiature optical displacement sensor in which optical elements are easily positioned with high accuracy. <Problem of Conventional Example 3> Further, in the optical displacement sensor shown in FIG. 14, since each optical element is integrally formed on the same substrate, the optical displacement sensor is small in size in which no positional deviation can occur between the optical elements. Although it constitutes a highly accurate displacement sensor, it has the following problems.

A normal semiconductor laser uses a cleavage plane at the emitting end surface. In this displacement sensor, the semiconductor laser 7 is used.
Since 02 is integrally formed with the optical waveguide 703 and the lens 704, its end face 707 is formed by dry etching. Since the distance between the end face 707 and the optical waveguide 703 is narrow, it is very difficult to protect the end face, and particularly in a semiconductor laser using a compound semiconductor material containing aluminum, stable oscillation cannot be obtained due to end face deterioration due to energization. The same applies to the photodiode 706. Further, a lens 704 for narrowing the beam is provided on the semiconductor substrate 70.
Since it is integrally formed on the lens 1, high controllability is required for the lens shape, and the process becomes complicated. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultra-compact and highly accurate optical displacement sensor that does not require protection of the emitting end face of a semiconductor laser and does not require a condenser lens.

[0015]

An optical displacement sensor according to the present invention as set forth in claim 1 is intended to solve the problem of the conventional example 1, and is a vertical cavity surface emitting device formed on a semiconductor substrate. The laser, the mirror separation support layer provided on the surface having the emission window of the vertical cavity surface emitting laser while avoiding the emission window, and a predetermined interval in parallel with the emission window of the vertical cavity surface emitting laser. A mirror layer disposed, a mirror support layer supported by the mirror separation support layer, the mirror support layer supporting the mirror layer so as to be displaceable with respect to an external force, and a light receiving element detecting the light intensity that changes according to the displacement of the mirror layer. Is equipped with.

An optical displacement sensor according to a second aspect of the present invention is to solve the problem of the second conventional example, and includes a vertical cavity surface emitting laser formed on a semiconductor substrate.
The light receiving element formed in the current blocking layer of the vertical cavity surface emitting laser, and the light emitting element of the vertical cavity surface emitting laser and the light receiving section of the light receiving element are provided on the surface having the light receiving section while avoiding the emission window and the light receiving section. And a light receiving element for emitting a light beam emitted from the vertical cavity surface emitting laser, which is arranged at a predetermined angle with respect to the emission surface of the vertical cavity surface emitting laser and the mirror spacing support layer. And a mirror support layer that is supported by the mirror spacing support layer and that supports the mirror layer so as to be displaceable with respect to an external force.

The present invention according to claim 3 is to solve the problem of the prior art example 3, in which a scale having a large number of diffraction gratings and two coherent light beams are incident on the scale, and the diffracted light beams are In a displacement sensor that outputs a signal proportional to the amount of movement of a moving object by attaching either one of the device body that interferes with each other and the change in the intensity of the interference light to the moving object and outputs two signals in opposite directions. A vertical cavity surface emitting laser formed on a semiconductor substrate to be emitted, and a mirror separation support layer provided on each of a front surface and a back surface having an emission window of the vertical cavity surface emitting laser while avoiding the emission window. , Two light beams emitted from the emission window of the vertical cavity surface emitting laser, which are arranged at a predetermined angle with respect to the emission window of the vertical cavity surface emitting laser, are directed to the same position on the diffraction grating. Mira to reflect The film includes a film, a mirror support layer supported by each mirror separation support layer and supporting each mirror film, and a light receiving element arranged at an interference position of diffracted light of two light beams generated by a diffraction grating. .

[0018]

According to the optical displacement sensor of the present invention as set forth in claim 1, for example, a resin layer such as polyimide serving as a mirror separation supporting layer is formed on the surface having the emission window of the vertical cavity surface emitting laser. After forming a metal film such as aluminum to be a mirror layer on it and further forming an insulating film such as silicon oxide to be a mirror support layer on it, an emission window of the vertical cavity surface emitting laser and its peripheral portion By selectively removing the resin layer on the top by wet etching, etc., a part between the surface having the emission window of the vertical cavity surface emitting laser and the metal film is made hollow, and the light receiving element is provided at a predetermined position. It is made by. Examples of the position where the light receiving element is provided include the back surface of the semiconductor substrate and the back surface of the mirror layer, which is a position facing the resonator portion of the vertical cavity surface emitting laser. As a result, the beam emitting surface of the vertical cavity surface emitting laser and the surface of the mirror layer are arranged in parallel with high accuracy, and the entire structure becomes extremely small.

The optical displacement sensor of the present invention as set forth in claim 2 is, for example, made of polyimide or the like serving as a mirror separation support layer on the surface having the emission window of the vertical cavity surface emitting laser and the light receiving portion of the light receiving element. A resin layer is formed, a V-shaped concave portion is formed in the resin layer by ion beam etching or the like, and a metal film such as aluminum to be a mirror layer is formed thereon,
Further, after forming an insulating film such as silicon oxide as a mirror support layer on it, the emission window of the vertical cavity surface emitting laser, the light receiving element and the resin layer on the periphery thereof are selectively etched by wet etching or the like. Then, the surface of the vertical cavity surface emitting laser having the emission window and the metal film are partially hollowed. As a result, the surface of the mirror layer is arranged at a predetermined angle with respect to the beam emission surface of the vertical cavity surface emitting laser with high accuracy, and the entire structure becomes extremely small.

In the optical displacement sensor of the present invention as defined in claim 3, for example, a resin layer such as a polyimide serving as a mirror separation supporting layer is formed on the front surface and the back surface of a vertical cavity surface emitting laser, and an ion beam is formed. A V-shaped recess is formed in each resin layer by etching or the like, a metal film such as aluminum to be a mirror layer is formed on each resin layer, and silicon oxide to be a mirror support layer is further formed on each metal film. After forming an insulating film such as, for example, the resin layer between the emission window of the vertical cavity surface emitting laser and the metal film is removed. Unlike the conventional semiconductor laser, the emission angles of the beams can be freely designed at both emission end faces of the vertical cavity surface emitting laser, so that it is not necessary to dispose a lens on the emission side of the laser.
In addition, in a normal semiconductor laser, it is necessary to stack a protective film on the end face, but since both emission end faces of the vertical cavity surface emitting laser can be entirely composed of a material such as GaAs which hardly deteriorates by conduction, a protective film is formed. Need not be formed.

[0021]

EXAMPLES Before describing the examples of the optical displacement sensor according to the present invention, the manufacturing method used in each example will be described. First, the most basic manufacturing method will be described with reference to FIG.

Step 1 [FIG. 1 (A1) (A2)]: Substrate 1
A mask 102 of an insulating film or the like is formed on 01, and rectangular windows 108 are formed at two locations by photolithography or the like. A cross section taken along line A2-A2 in FIG.
It shows in (A2). In FIG. 1 (A2), y1, y2 and t are set sufficiently larger than x.

Step 2 [FIG. 1 (B1) (B2)]: The lower side of the region sandwiched by the rectangular windows 108 is completely removed by wet etching or the like. For example, a compound semiconductor material such as GaAs is etched with an etching solution such as (phosphoric acid: hydrogen peroxide solution: water). As the etching progresses, as shown in FIG. 1B2, a rectangular window 108 is eventually formed.
The lower side of the portion 103 sandwiched between the two is completely hollow, and the portion 103 sandwiched by the rectangular window 108 is supported only by the mask 102 on the substrate.

In the structure manufactured in this way, the portion 103 sandwiched by the rectangular windows 108 is displaced by the shape and Young's modulus of the material when a downward force is applied. Figure 1 (C
1) (C2) shows a structure in which rectangular windows are provided at four places and cross-shaped beams are formed as a modification of FIGS. 1 (B1) and (B2). This structure is not easily affected by twisting in a specific direction, and the mask 104 is displaced in the vertical direction while maintaining the position parallel to the etching surface 105 of the substrate.

As a modification of the above, a method of manufacturing a structure having a mirror inclined at an arbitrary angle on the lower surface of the portion sandwiched by the rectangular windows will be described with reference to FIG. Step 1 [FIG. 2 (A)]: A resin 107 such as polyimide is applied on the semiconductor substrate 106 such as GaAs for several tens to several hundreds of μm.

Step 2 [FIG. 2 (B)]: A groove portion 109 is formed in the resin 107 in an oblique direction at an arbitrary angle by ion beam etching or the like. Step 3 [FIG. 2 (C)]: A groove is formed in an oblique direction at an arbitrary angle by ion beam etching from the opposite side to form a V-shaped recess.

Step 4 [FIG. 2D]: A metal film 110 of aluminum or the like is formed by vapor deposition or the like, and an insulating film 111 of silicon oxide or the like is formed thereon by sputtering or the like. Step 5 [FIG. 2E]: An etching mask 112 such as a resist is applied, and rectangular windows 113 are formed at two locations by photolithography or the like.

Step 6 [FIG. 2 (F)]: The insulating film 111 and the metal film 110 are vertically etched by dry etching,
The etching mask 112 is peeled off. Step 7 [FIG. 2G]: The resin 107 is selectively removed by wet etching to form a mirror 114 having an arbitrary angle and sandwiched by rectangular windows.

When a downward force is applied to the mirror 114, the structure thus manufactured is displaced according to the shape of the material and the Young's modulus. By setting the inclination angle of the mirror 114 arbitrarily, the light beam can be reflected in a desired direction.

An example using the manufacturing method described so far is shown below. <First Embodiment> FIG. 3 shows an optical displacement sensor according to a first embodiment of the present invention. A resin layer 203 made of polyimide or the like is provided on the peripheral portion of the surface of the p-type electrode 201 of the vertical cavity surface emitting laser 202. The resin layer 203 supports a metal film 204 such as aluminum used as a mirror and an insulating film 205 such as silicon oxide formed thereon. The upper portion of the window of the vertical cavity surface emitting laser 202 is hollow, and the mirror 206, which is a portion sandwiched between the windows formed in the metal film 204 and the insulating film 205, has the pressure sensitive element 222 provided thereon. When an external force is applied, it is displaced according to the external force. On the back surface of the vertical cavity surface emitting laser 202, an n-type electrode 221 and an insulating film 22 are provided.
A light receiving element 207 such as a photodiode is attached via 0. The vertical cavity surface emitting laser 202 and the light receiving element 207 are connected to an LD and PD power source 208 that supplies electric power to them through an electric wiring 209. Further, the light receiving element 207 is connected to the arithmetic unit 210 which receives the output.

Displacement detection by this optical displacement sensor is carried out in the same manner as in the conventional example shown in FIG. That is, when the pressure-sensitive element 222 receives an external force, the mirror 206 is displaced according to the Young's modulus of the elastic body forming the pressure-sensitive element 222, and the light receiving element 207 emits a pulse shape due to light interference similar to FIG. 12B. The waveform of is output. The displacement is obtained by counting the number of output fluctuations in the arithmetic unit 210. One cycle of this waveform is λ / 2 (when λ = 1 μm,
Since it corresponds to 0.5 μm), its displacement is required with high accuracy.

As described above, according to this embodiment, a highly precise and ultra-compact optical displacement sensor can be obtained. Next, a method of manufacturing the optical displacement sensor of this embodiment will be described with reference to FIG.

Step 1 [FIG. 4 (A)]: n-type semiconductor substrate 2
11, the n-type semiconductor multilayer mirror layer 212, the active layer 213, and the p-type semiconductor multilayer mirror layer 214 are laminated. Step 2 [FIG. 4 (B)]: Vertical cavity surface emitting laser 2
02, the p-type semiconductor multilayer mirror layer 21 is left.
4, the active layer 213 and the n-type semiconductor mirror layer 212 are removed, and a resin 215 such as polyimide is embedded in the portion.
A p-type electrode 216 is formed thereon, and an emission window is opened by photolithography. For filling, a semiconductor material may be used instead of the resin 215.

Step 3 [FIG. 4C]: A resin layer 203 such as polyimide, a metal film layer 204 such as aluminum, and an insulating film layer 205 such as silicon oxide are sequentially formed. Step 4 [FIG. 4 (D)]: insulating film layer 205 and metal film layer 20
4 is patterned by photolithography to form a window, and the resin layer 203 is selectively removed by wet etching to leave a space between the mirror 206 and the resonator portion. This step corresponds to the step relating to FIG. 1 described above.

Step 5 [FIG. 4 (E)]: n-type semiconductor substrate 2
After the n-type electrode 221 and the insulating film 220 are formed in a predetermined shape on the back surface of 11, the light receiving element 207 such as a photodiode
Are bonded by bonding or the like to complete the optical displacement sensor of this embodiment described above.

In the present embodiment, the light receiving element 207 is mounted on the back surface of the vertical cavity surface emitting laser 202, but it may be provided on the mirror 206. Alternatively, the photodiode may be formed in the n-type semiconductor substrate. <Second Embodiment> FIG. 5 shows an optical displacement sensor according to a second embodiment of the present invention. Photodiode 301 and p-type electrode 3
A resin layer 305 such as polyimide is formed on the surface of the vertical cavity surface emitting laser 304 on which 02 and 303 are formed, and a metal film 307 such as aluminum used as the mirror 306 is formed on the resin layer 305, and further thereon. An insulating film 308 of silicon oxide or the like is formed on. The window portion of the vertical cavity surface emitting laser 304 is in a hollow state, and the mirror 306 which is a portion sandwiched by two windows penetrating the insulating film 308 and the metal film 307 is displaced with respect to an external force. It has a structure that The mirror 306 has a shape in which an upper part of the window of the vertical cavity surface emitting laser 304 has a constant inclination angle. Since the cross-sectional shape of the mirror 306 is symmetrical, there is little twist when it is displaced in the vertical direction. The vertical cavity surface emitting laser 304 and the photodiode 301 are connected to an LD and PD power source 309 that supplies electric power to them through an electric wiring 310.

The displacement detection by this optical displacement sensor is carried out in the same manner as in the conventional example shown in FIG. When the mirror 306 receives an external force, the mirror 306 is displaced according to the Young's modulus of the elastic body forming the mirror. The light beam emitted from the vertical cavity surface emitting laser 304 is reflected by the mirror 306 and enters the photodiode 301. The output of the photodiode 301 and the distance z from the vertical cavity surface emitting laser 304 to the photodiode 301 via the mirror 306 have the same relationship as in FIG. 13B. The distance z ″ between the vertical cavity surface emitting laser 304 and the mirror 306 can be obtained by calculating the output of 301 by the arithmetic unit 311. If the light receiving area of the photodiode 301 is always included in the beam spread of the vertical cavity surface emitting laser 304, the direction of displacement can also be detected.

The method of manufacturing the optical displacement sensor of this embodiment will be described below with reference to FIGS. 6 and 7. Step 1 [FIG. 6 (A)]: The n-type semiconductor multilayer mirror layer 312, the active layer 313, and the p-type semiconductor multilayer mirror layer 314 are sequentially stacked on the n-type semiconductor substrate 311.

Step 2 [FIG. 6B]: The p-type semiconductor multilayer mirror layer 314, the active layer 313, and the n-type semiconductor mirror layer 3 are left, leaving the cavity portion of the vertical cavity surface emitting laser 304.
12, the thin p-type semiconductor layer 315 and the thin n-type semiconductor layer 316 are buried in this order.

Step 3 [FIG. 6C]: A p-type region 317 is formed in a part of the buried layer by impurity diffusion or the like to manufacture a photodiode. Step 4 [FIG. 6D]: An insulating film 319 of silicon oxide or the like is formed on such a structure, and after patterning so that the electrode can be taken out from the p-type region of the photodiode without short circuit, p The electrodes 318 are stacked and the emission window of the vertical cavity surface emitting laser 304 and the light receiving window of the photodiode 301 are formed by photolithography. The thickness of the insulating film 319 is about 3000 angstroms,
The value is smaller by two digits or more than the resin layer (several tens to several hundreds of μm) provided thereon in a later step, and there is no fear of affecting the inclination of the finally formed mirror.

Step 5 [FIG. 7 (A)]: After forming the resin layer 321 such as polyimide, this is etched into a V shape at an arbitrary angle by ion beam etching or the like. Step 6 [FIG. 7 (B)]: Metal film 322 of aluminum or the like
An insulating film 323 of silicon oxide or the like is formed, an n-type electrode 324 is laminated on the back surface, and an emission window is formed by photolithography.

Step 7 [FIG. 7 (C)]: The insulating film layer 323 and the metal film layer 322 are patterned by photolithography to form a window, and then the resin layer 305 is selectively removed by wet etching to form a vertical line. The cavity of the cavity surface emitting laser 304 and the upper portion of the photodiode are made hollow. As a result, the mirror 306 that is displaced with respect to the external force is formed, and the optical displacement sensor of this embodiment is completed.

FIG. 8 shows an example of specific dimensions of this embodiment. In this example, the numerical aperture (2r) of the vertical cavity surface emitting laser is 10 μm, the light receiving area diameter of the photodiode is 5 μm, and the tilt angle of the mirror (the angle made by the normal to the mirror with respect to the vertical direction) is set. It is set at 30 °. In this setting, the distance between the centers of the vertical cavity surface emitting laser and the photodiode is 45 μm, the distance between the mirror and the emission surface (Z ″ in FIG. 5) is 30 μm, and the displacement width is 10 μm.
You can set up to m. <Third Embodiment> FIG. 9 shows an optical displacement sensor according to a third embodiment of the present invention. A resin layer 403 of polyimide or the like is formed on the surface of the vertical cavity surface emitting laser 402 having the p-type electrode 401 formed thereon, and a metal film 405 of aluminum or the like used as a mirror and an insulating film of silicon oxide or the like are used thereon. 406 is formed. Similarly, a resin layer 407 such as polyimide is also formed on the back surface of the vertical cavity surface emitting laser 402.
Is formed, and a metal film 409 made of aluminum or the like used as a mirror and a thick insulating film 41 made of silicon oxide or the like are formed thereon.
0 is formed. Vertical cavity surface emitting laser 40
The surface side of 2 has a shape in which a mirror 404 composed of a metal film 409 and an insulating film 410 projects like an eaves having a constant inclination angle. Vertical cavity surface emitting laser 4
Similarly, the back surface side of 02 also has a shape in which a mirror 408 composed of a metal film 409 and an insulating film 410 projects like an eaves having a constant inclination angle. The light receiving element 41 such as a photodiode is provided on the side surface of the substrate facing the diffraction grating 416.
Two are provided. An n-type electrode region 411 is formed on the opposite side surface of the substrate. The vertical cavity surface emitting laser 402 and the light receiving element 412 are connected to an LD power supply 413 and a PD power supply 414 which supply electric power to them, through an electric wiring 415. Diffraction gratings 416 are arranged at the intersections of the light beams emitted from both end surfaces of the vertical cavity surface emitting laser 402.

The two light beams emitted from both end faces of the vertical cavity surface emitting laser 402 are mirrors 404 and 4.
After being reflected by 08, the light is diffracted by the diffraction grating 406 and interferes with each other.
Then, the same waveform as that shown in FIG. 14B is obtained. The movement amount of the diffraction grating 406 is obtained based on this waveform.

The method of manufacturing the optical displacement sensor of this embodiment will be described below with reference to FIGS. Step 1 [FIG. 10 (A)]: The n-type semiconductor multilayer mirror layer 418, the active layer 419, and the p-type semiconductor multilayer mirror layer 420 are laminated on the n-type semiconductor substrate 417.

Step 2 [FIG. 10 (B)]: The p-type semiconductor multilayer mirror layer 420, the active layer 419, and the n-type semiconductor mirror layer 418 are removed, leaving the resonator portion of the vertical cavity surface emitting laser 402. , A resin 421 such as polyimide is embedded, a p-type electrode 422 is formed thereon, and an emission window is opened by photolithography. The filling may be performed using a semiconductor material instead of the resin 421 such as polyimide.

Step 3 [FIG. 10 (C)]: A resin layer 423 made of polyimide or the like is formed and etched into a V shape at an arbitrary angle by ion beam etching or the like. Step 4 [FIG. 10 (D)]: Metal film 42 of aluminum or the like
4 and an insulating film 425 of silicon oxide or the like are formed, and the insulating film 425
The metal film 424 is patterned by photolithography.

Step 5 [FIG. 11 (A)]: Similarly, a resin layer 426 made of polyimide or the like is formed on the back surface side, and is etched into a V shape at an arbitrary angle by ion beam etching or the like. Then, a metal film 424 made of aluminum or the like and an insulating film 425 made of silicon oxide or the like are stacked, and the insulating film 428 and the metal film 427 are patterned by photolithography.

Step 6 [FIG. 11B]: The resin layers 423 and 426 are selectively removed by wet etching, and p
The mold electrode 422 is exposed. Step 7 [FIG. 11 (C)]: An n-type electrode 411 is provided on the side surface (on the right side of the figure) of the n-type semiconductor substrate 417, and the light beam emitted from the vertical cavity surface emitting laser 402 is diffracted and incident. A light receiving element 412 such as a photodiode is provided on the side surface to complete the optical displacement sensor of this embodiment.

The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and various modifications and applications are possible within the scope of the gist of the present invention. .

1. (Corresponding to the first embodiment) (Structure) A vertical cavity surface emitting laser formed on a semiconductor substrate and a mirror provided on a surface having an emission window of the vertical cavity surface emitting laser while avoiding the emission window. A separation support layer, a mirror layer arranged at a predetermined interval in parallel to the emission window of a vertical cavity surface emitting laser, and a mirror layer supported by the mirror separation support layer and capable of being displaced by an external force An optical displacement sensor comprising: a mirror support layer that supports the light-receiving element; (Operation) Such an optical displacement sensor is manufactured using semiconductor technology. For example, on a surface having an emission window of a vertical cavity surface emitting laser, a resin layer such as a polyimide serving as a mirror separation supporting layer is formed, and a metal film such as aluminum serving as a mirror layer is formed on the resin layer. After forming an insulating film such as silicon oxide serving as a mirror support layer on the top, the emission window of the vertical cavity surface emitting laser and the resin layer on the periphery thereof are selectively removed by wet etching or the like, The vertical cavity surface emitting laser is manufactured by partially hollowing out the surface having the emission window of the vertical cavity surface emitting laser and providing a light receiving element at a predetermined position. Examples of the position where the light receiving element is provided include the back surface of the semiconductor substrate and the back surface of the mirror layer, which is a position facing the resonator portion of the vertical cavity surface emitting laser. (Effect) Since such an optical displacement sensor is manufactured by using semiconductor technology, the beam emitting surface of the vertical cavity surface emitting laser and the surface of the mirror layer are arranged in parallel with high accuracy, and The configuration of is also very small.

2. (Corresponding to the second embodiment) (Structure) Vertical cavity surface emitting laser formed on a semiconductor substrate, light receiving element formed in the current blocking layer of the vertical cavity surface emitting laser, and vertical cavity Mirror separation support layer provided on the surface having the emission window of the die surface emitting laser and the light receiving portion of the light receiving element and avoiding the emission window and the light receiving portion, and a predetermined angle with respect to the emission window of the vertical cavity surface emitting laser The mirror layer, which is arranged with a predetermined space between the mirror layer and reflects the light beam emitted from the vertical cavity surface emitting laser toward the light receiving element, and the mirror layer, which is supported by the mirror separation supporting layer, is applied to the external force. An optical displacement sensor having a mirror support layer which is supported so as to be displaceable with respect to the mirror. (Operation) Such an optical displacement sensor is manufactured using semiconductor technology. For example, a resin layer such as polyimide serving as a mirror separation support layer is formed on a surface having an emission window of a vertical cavity surface emitting laser and a light receiving portion of a light receiving element, and a V-shaped resin layer is formed on the resin layer by ion beam etching or the like. After forming a concave portion, forming a metal film such as aluminum as a mirror layer on the concave portion, and further forming an insulating film such as silicon oxide as a mirror supporting layer on the concave portion, emitting a vertical cavity surface emitting laser. The window, the light receiving element, and the resin layer on the periphery of the window are selectively removed by wet etching or the like to partially hollow the surface having the emission window of the vertical cavity surface emitting laser and the metal film. It is made by. (Effect) Since such an optical displacement sensor is manufactured by using semiconductor technology, the surface of the mirror layer is arranged at a predetermined angle with high accuracy with respect to the beam emission surface of the vertical cavity surface emitting laser. At the same time, the overall configuration will be ultra-compact.

3. (Corresponding to the third embodiment) (Structure) A scale provided with a large number of diffraction gratings, and an apparatus main body for injecting two coherent lights into the scale and causing the diffracted lights to interfere with each other to detect the intensity change of the interference light A vertical resonator type surface formed on a semiconductor substrate, which emits two light beams in opposite directions, in a displacement sensor in which one of the two is attached to a moving object and outputs a signal proportional to the amount of movement of the moving object. A light emitting laser, a mirror separation support layer provided on each of a front surface and a back surface having an emission window of a vertical cavity surface emitting laser while avoiding the emission window, and a predetermined for the emission window of the vertical cavity surface emitting laser. The mirror film that reflects the two light beams emitted from the emission window of the vertical cavity surface emitting laser at the same angle to the diffraction grating toward the same position, and is supported by each mirror separation support layer. , Each mirror An optical displacement sensor comprising a mirror support layer for supporting a film and a light receiving element arranged at an interference position of diffracted light of two light beams generated by a diffraction grating. (Operation) Such an optical displacement sensor is manufactured using semiconductor technology. For example, a resin layer such as a polyimide serving as a mirror separation supporting layer is formed on the front and back surfaces of a vertical cavity surface emitting laser, and a V-shaped recess is formed in each resin layer by ion beam etching or the like, and each resin is formed. After forming a metal film such as aluminum to be a mirror layer on each layer, and further forming an insulating film such as silicon oxide to be a mirror support layer on each metal film, emission of a vertical cavity surface emitting laser It is manufactured by removing the resin layer between the window and the metal film. (Effect) It is possible to obtain a compact and highly accurate optical displacement sensor that does not require protection of the exit end face and does not require a condenser lens.

4. (Corresponding to the first and second embodiments) (Structure) In the above item 1 or 2, the mirror layer and the mirror support layer have a cross-shaped beam structure, and the central portion thereof is a vertical resonator type. An optical displacement sensor installed to face the emission window of a surface emitting laser. (Operation) Since it has a cross-shaped beam structure, twisting is unlikely to occur. (Effect) Since twisting is unlikely to occur, the accuracy of external force detection is improved.

5. (Corresponding to the first embodiment) (Structure) The optical displacement sensor according to the above 1, wherein the light receiving element is a photodiode formed inside the back surface of the substrate of the vertical cavity surface emitting laser. (Operation) The photodiode is manufactured by applying a semiconductor manufacturing technique such as impurity diffusion to the back surface of the semiconductor substrate which is the substrate of the vertical cavity surface emitting laser. (Effect) Since the light receiving element is integrally formed on the semiconductor substrate, a smaller optical displacement sensor can be obtained.

6. (Corresponding to the second embodiment) (Structure) The optical displacement sensor according to the above item 2, wherein the cross-sectional shapes of the beams of the mirror layer and the mirror support layer are symmetrical. (Function) Since the cross-sectional shapes of the beams of the mirror layer and the mirror support layer are symmetrical with each other, for example, V-shaped, twisting is unlikely to occur. (Effect) Since twisting is unlikely to occur, the accuracy of external force detection is improved.

7. (Corresponding to the second embodiment) (Structure) The optical displacement sensor according to the above item 2, wherein the light receiving portion of the light receiving element is always positioned in the light beam of the vertical cavity surface emitting laser. (Operation) The output of the light receiving element changes depending on the direction and amount of displacement. (Effect) The direction of displacement can also be detected.

[0058]

According to the present invention described in claim 1, a microminiature optical displacement sensor in which the beam emitting surface of a vertical cavity surface emitting laser and the surface of a mirror layer are arranged in parallel with high accuracy. Is obtained. As a result, various problems such as poor workability when mounting the elastic body, poor position accuracy, and further increase in size of the device are avoided.

According to the second aspect of the present invention, the surface of the mirror layer is arranged at a predetermined angle with respect to the beam emission surface of the vertical cavity surface emitting laser with a high degree of accuracy, and the optical displacement is very small. The sensor is obtained. As a result, various problems such as poor workability when mounting the elastic body, poor position accuracy, and further increase in size of the device are avoided.

According to the third aspect of the present invention, since the radiation angle of the beam can be freely designed, a condenser lens is not required, and the exit end face can be made of a material with almost no deterioration due to electrical conduction, thereby protecting the exit end face. A compact, high-precision optical displacement sensor that does not require is obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a basic manufacturing method used in an embodiment of the present invention.

FIG. 2 is a diagram for explaining another basic manufacturing method used in the embodiment of the present invention.

FIG. 3 is a diagram showing an optical displacement sensor according to a first embodiment of the present invention.

FIG. 4 is a diagram for explaining a manufacturing process of the optical displacement sensor of FIG.

FIG. 5 is a diagram showing an optical displacement sensor according to a second embodiment of the present invention.

FIG. 6 is a view for explaining a manufacturing process of the optical displacement sensor of FIG. 5, showing a first step.

FIG. 7 is a diagram for explaining a manufacturing process of the optical displacement sensor of FIG. 5, showing the process following FIG. 6;

8 is a diagram showing an example of specific dimensions of the optical displacement sensor of FIG.

FIG. 9 is a diagram showing an optical displacement sensor according to a third embodiment of the present invention.

FIG. 10 is a diagram for explaining a manufacturing process of the optical displacement sensor of FIG. 9, showing a first step.

FIG. 11 is a diagram for explaining a manufacturing process of the optical displacement sensor of FIG. 9, which is a diagram showing a process following FIG. 10.

FIG. 12 is a diagram showing a conventional optical displacement sensor (conventional example 1) using a vertical cavity surface emitting laser as a light source.

FIG. 13 is a diagram showing a conventional optical displacement sensor (conventional example 2) using a vertical cavity surface emitting laser as a light source.

FIG. 14 is a diagram showing a conventional optical displacement sensor (conventional example 3) known as an encoder that detects the amount of movement of a diffraction grating by utilizing interference.

[Explanation of symbols]

202 ... Vertical cavity surface emitting laser, 203 ... Resin layer, 204 ... Metal film, 205 ... Insulating film, 207 ... Light receiving element.

Claims (3)

[Claims] 1. A vertical cavity surface emitting laser formed on a semiconductor substrate, a mirror spacing support layer provided on a surface having an emission window of the vertical cavity surface emitting laser while avoiding the emission window, and a vertical direction. A mirror layer arranged at a predetermined interval in parallel with the emission window of the cavity surface emitting laser; and a mirror support layer supported by the mirror spacing support layer and supporting the mirror layer so as to be displaceable with respect to an external force. , An optical displacement sensor including a light receiving element that detects a light intensity that changes according to the displacement of the mirror layer. 2. A vertical cavity surface emitting laser formed on a semiconductor substrate, a light receiving element formed in a current blocking layer of the vertical cavity surface emitting laser, and an emission of the vertical cavity surface emitting laser. A mirror separating support layer provided on the surface having the window and the light receiving portion of the light receiving element while avoiding the emission window and the light receiving portion,
A mirror layer, which is arranged at a predetermined angle with respect to the emission window of the vertical cavity surface emitting laser and is spaced at a predetermined interval, and reflects the light beam emitted from the vertical cavity surface emitting laser toward the light receiving element. An optical displacement sensor comprising: and a mirror support layer, which is supported by the mirror separation support layer and supports the mirror layer so as to be displaceable with respect to an external force. 3. A scale provided with a large number of diffraction gratings and a device body for injecting two coherent light beams into the scale and causing the diffracted light beams to interfere with each other to detect a change in the intensity of the interference light beam. In a displacement sensor that is attached to an object and outputs a signal proportional to the amount of movement of a moving object, a vertical cavity surface emitting laser formed on a semiconductor substrate that emits two light beams in opposite directions, and a vertical resonance Of the vertical cavity surface emitting laser and the mirror spacing support layers provided on the front surface and the back surface of the vertical cavity surface emitting laser, avoiding the exit window, and arranged at a predetermined angle with respect to the exit window of the vertical cavity surface emitting laser. , A mirror film that reflects two light beams emitted from an emission window of a vertical cavity surface emitting laser toward the diffraction grating toward the same position, and each mirror film supported by each mirror separation support layer Mira -An optical displacement sensor including a support layer and a light receiving element arranged at an interference position of diffracted light of two light beams generated by a diffraction grating.