JP3308569B2 - Optical scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used for various optical devices such as a bar code reader, and more particularly, to miniaturization and high accuracy thereof.

[0002]

2. Description of the Related Art In recent years, optical scanning devices and optical devices such as optical printers, facsimile machines, bar code readers, and the like that use the same have been downsized by improving the technology for manufacturing optical components with high precision and mounting technology. Light weight and low cost have been achieved, and are widely used in general. For example, a barcode reader is a device that reads a barcode indicating an identification code unique to a product with laser light or LED light, and collects and analyzes information necessary for management at the point of sale, and uses it for product management and inventory management. be able to. This bar code reader is roughly classified into three types: a pen type, a touch type, and a stationary type.

For example, in a stationary bar code reader, a laser beam generated by a laser device is condensed by a light converging element such as a lens and further deflected by an optical deflector to scan the bar code. Since the intensity of the reflected light from the bar code is modulated according to the bar code, the reflected light is condensed by a condensing element and converted to an electric signal by a photodetector. It corresponds to. After the electric signal is shaped by a signal waveform shaping circuit, it is converted by a symbol demodulation circuit into a number corresponding to a bar code and output.

[0004] Among the optical components constituting the stationary bar code reader having such a configuration, for example, a He-Ne laser is used as a laser light source of a laser device. Since the output is being advanced, it is expected that a high-output visible light semiconductor laser will be able to be replaced in the near future.

On the other hand, mechanical scanners such as a rotary polygon mirror (polygon mirror), a galvano mirror, and a holographic scanner have been used as optical deflectors. Although the introduction of ultra-precision cutting machines has led to lower prices and smaller sizes, movable mirrors and condenser lenses have been factors that have hindered miniaturization of barcode readers.

[0006]

The fixed type bar code reader reads a bar code at a high speed and at a remote place.
It is suitable to be installed in a cash register of a supermarket or an automatic reading line in a factory automation, but the price is high.
There is a disadvantage that the installation place is large. While there is a strong possibility that downsizing of the light source will be achieved by practical use of the semiconductor laser, downsizing of the mechanical deflector is strongly desired.

In consideration of the future miniaturization of a bar code reader, an optical waveguide type optical system for confining light within a plane, not an optical system of a light source, a lens system, and a rotating mirror of a system that propagates in the present space. It can be said that is more desirable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points. An optical deflector is manufactured by micromachining, and some of a semiconductor laser light source, an optical scanning means, a light condensing system, and a light receiving element are arranged on a plane. It is an object of the present invention to provide a compact and highly accurate optical scanning device by integration.

[0009]

In order to achieve the above object, an optical scanning device according to the present invention comprises a light source, a light deflecting and emitting section for deflecting and emitting light from the light source to scan a subject, and And a photodetector for detecting light reflected from a subject, and in particular, at least the light deflection emission section and the photodetector are integrally formed on the same semiconductor substrate. And

[0010] In particular, the light deflection / emission portion includes a torsion bar formed in the recess of the semiconductor substrate and a pair of electrodes facing the torsion bar, and a torsion formed in the recess of the semiconductor substrate. A torsion bar including a bar, a pair of electrodes formed on the torsion bar, and an electrode facing the torsion bar, a cantilever having a waveguide and a grating, and a shape memory alloy and a thin film heater A torsion bar having conductivity and reflectivity formed in a concave portion of the semiconductor substrate, and an electrode facing the torsion bar, a torsion bar formed in a concave portion of the semiconductor substrate, A ferroelectric formed on a torsion bar, and a comb-shaped electrode formed on the ferroelectric, etc. It is needed.

[0011]

That is, an optical scanning device according to the present invention comprises a light source, a light deflecting / emitting section for deflecting and emitting light from the light source to scan a subject, and a photodetector for detecting reflected light from the subject. Among them, at least the light deflection emission section and the light detector are formed integrally on the same semiconductor substrate by micromachining.

That is, in the optical scanning device of the present invention, in order to deflect light on a semiconductor crystal substrate such as a silicon substrate,
A laser beam deflected by an optical deflector, such as a micro-plane reflecting mirror whose angle can be changed, or a reflecting mirror whose curvature can be changed, scans an object such as a bar code and reflects the reflected light to the same semiconductor. Detection is performed by a light receiving element formed on the substrate.

What is important here is a technique for forming a micro-reflecting mirror for performing optical scanning on a silicon substrate. In this technique, a high-concentration p-type layer is formed using crystal anisotropic etching of silicon. Utilizing the characteristics of anisotropic etching such as being an etching stop layer and shifting the pattern direction from the <110> direction to advance side etching.

The silicon layer serving as a reflecting mirror is a high-concentration p-type layer (hereinafter referred to as a p ⁺⁺ layer), and the pattern direction of this layer is <100.
> Direction. In crystal anisotropic etching, (111)
The surface is the surface with the slowest etching rate, but (100)
By selecting the pattern direction of the p ⁺⁺ layer to <100> using a crystal, the silicon crystal under the p ⁺⁺ layer is side-etched, so that the p ⁺⁺ layer floats from the silicon substrate after long-time etching. And can be used as a movable mirror.

Further, even when an SOI substrate having a silicon / SiO ₂ / silicon structure formed by direct bonding of the substrate is used, the movable mirror released from the substrate by anisotropic etching and removing the SiO ₂ sacrificial layer. Can be obtained.

The silicon mirror obtained in this manner is connected to the silicon substrate by a thin-film beam (torsion bar), and the mirror is vibrated by electrostatic drive to form a light deflector. This light deflector can be used as a surface reflection type light deflector and an end face (side) emission type light emitter. In the light emitter, an optical waveguide can be integrated on the same substrate. In this case, a grating element is used. Thus, an optical function such as focusing of laser light can be performed on a plane, and the number of optical components can be reduced, and an optical deflection / emission device that does not require optical axis alignment can be obtained.

Further, a line sensor is integrated as a light receiving element on a silicon substrate having a reflecting mirror, and mechanical light deflection and detection of a reflection intensity pattern from a bar code are performed on the same substrate.

Therefore, since a small-sized light deflection / emission device can be used, the optical scanning device itself can be reduced in size, and the light deflection / light emission device and the photodetector are integrally formed on the same substrate. In addition, it is possible to eliminate bothersome troubles such as the alignment of the two, and to perform the high-accuracy alignment, thereby enabling the high-accuracy detection.

[0019]

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

FIG. 1 is a perspective view showing a configuration of a bar code reader to which an optical scanning device according to a first embodiment of the present invention is applied, and FIG. 2 is a block diagram of the bar code reader.

In these figures, 11 is a semiconductor laser as a laser device, 12 is an optical system as a light focusing element for condensing and collimating a laser beam 13, and 14 is a laser focused to several μmφ. Light, 15 is a light deflector as a light deflector, 16 is deflected light traveling from the light deflector 15 to a bar code 17 as a subject, and 18 is a bar code 17
19 is a condensing lens as a condensing element,
Reference numeral 0 denotes light focused by the condenser lens 19, and reference numeral 21 denotes a light detection line sensor as a photodetector. at least,
The optical deflector 15 and the light receiving line sensor 21 can be integrated on the same silicon substrate 22, and have advantages such as simplification of the optical system of the bar code reader, reduction in size and weight, easiness of assembly, high accuracy, and the like. .

Reference numeral 23 denotes a signal waveform shaping circuit for shaping the waveform of the electric signal photoelectrically converted by the light receiving line sensor 21, and reference numeral 24 denotes a symbol demodulation circuit for converting the waveform-shaped electric signal into a number corresponding to a bar code. is there.

FIG. 3 shows the configuration of an electrostatically driven torsion bar type optical deflector as a micro optical deflector 15 manufactured by micromachining used in the optical scanning device of the first embodiment. In the drawings, (A) is a plan view, and (B) and (C) are cross-sectional views taken along lines BB and CC in (A), respectively.

In these figures, reference numeral 22 denotes a crystal plane (10
0), and 25 (25a, 25a,
25b) is a high concentration p-type buried layer (hereinafter referred to as a p ⁺⁺ buried layer),
26 is an n-type epitaxial layer, 27 is a high-concentration p-type diffusion layer (hereinafter, p ⁺⁺ diffusion layer), 28 is a silicon thermal oxide film (SiO 2
₂ ), etc., and 29 (29a, 29b, 29c) is A
The u / Cr metal film 30 is a p-type diffusion layer.

The p-type diffusion layer 30 has a contact hole 31
Is electrically ohmic connected to the Au / Cr metal film 29 (29a, 29b). The p-type diffusion layer 30 is
^{++ The} buried layer 25 (25a, 25b) has been reached. These two p ⁺⁺ buried layers 25a, 25b are electrically separated from each other and can be electrically biased independently via the electrodes 29a, 29b.

The electrode 29c is a third metal electrode insulated from the p ⁺⁺ diffusion layer via the SiO ₂ film 28, and functions as a reflector. The third electrode 29c is attracted to the p ⁺⁺ buried layers 25a and 25b by electrostatic attraction.
That is, usually, the third electrode 29c is grounded, and the angle of the third electrode surface can be changed by alternately applying a negative voltage to the first and second electrodes 29a and 29b. A voltage control circuit 32 for applying the voltage is connected to the first to third electrodes 29a, 29b, 29c. Also, the third
The p ⁺⁺ diffusion layer 27 below the electrode 29c is separated from the substrate 22 and is connected to the substrate 22 via the insulating film 28 to form a torsion bar.

FIGS. 4A to 4F are cross-sectional views taken along the line BB of FIG. 3A for explaining the outline of the method of manufacturing the electrostatic drive torsion bar optical deflector of FIG. It is equivalent. In these drawings, hatching indicating a cross section is omitted for simplification of the drawings. First, as shown in FIG. 4A, an n-type silicon substrate 22 having a crystal plane (100) is
At positions corresponding to the p ⁺⁺ buried layers 25a and 25b in FIG.
Form a p ⁺⁺ diffusion layer. This corresponds to FIG.
In the step shown in (1), when silicon anisotropic etching is performed to separate the torsion bar from the substrate 22, the impurity concentration is set to 7 × 10 ¹⁹ cm so as to serve as a stop layer.
Choose ^-3 or more. Next, as shown in FIG. 4B, an n-type epitaxial layer 26 is grown, and p ⁺ reaching the p ⁺⁺ buried layers 25a and 25b from the surface. The diffusion layer 30 is formed.

Next, as shown in (C) of FIG. 4, p ⁺ A p ⁺⁺ diffusion layer 27 constituting a torsion bar is formed between the diffusion layers 30. At this time, the pattern of the p ⁺⁺ diffusion layer 27 is rectangular as shown in FIG. 3A, and the directions of the four sides are <100> directions. This is because the n-type epitaxial layer 26 under the p ⁺⁺ diffusion layer 27 is removed by side etching in a separation step shown in FIG.

Next, as shown in FIG. 4D, an insulating film, for example, a thermal oxide film 28 is formed on the front and back sides of the substrate, and p ⁺
A contact hole 31 is formed in the diffusion layer 30 and 300
While being heated to about ° C, Cr is deposited by about 500 angstroms, and then Au is continuously deposited by about 3000 angstroms. Then, by performing vacuum evaporation of Cr while heating the substrate, p ⁺ An ohmic contact can be made with the diffusion layer 30 electrically.

Next, as shown in FIG.
Cr is patterned by photolithography like the electrodes 29a, 29b, and 29c in FIG.
O ₂ 28 is processed by photolithography and a window is opened to separate the torsion bar. The inside of the pattern of the window 33 is the p ⁺⁺ diffusion layer 27 (the electrode 29 of FIG.
c), the outside is the <110> direction, and p ⁺ It is located between the diffusion layer 30 and the p ⁺⁺ diffusion layer 27. Subsequently, a window for separation is opened in the back surface insulating film 28.

Next, as shown in FIG. 4F, the torsion bar is separated from the substrate using a silicon anisotropic etching solution. For the anisotropic etching, a mixed solution (EPW solution) of ethylenediamine, pyrocatechol, and water, a KOH solution, or the like is used. EPW liquid is SiO ₂ , Si ₃ N ₄ , Au /
Cr is hardly etched and the p-type impurity concentration is 7
In the case of the diffusion layer 27 of × 10 ¹⁹ cm ⁻³ , the etching rate sharply decreases.
⁺⁺ N-type epitaxial layer 26 under diffusion layer 27 is removed by side etching and etching from the back surface. The insulating film 2 supporting the p ⁺⁺ diffusion layer 27 and connecting to the substrate.
The epitaxial layer below 8 is removed by gradually side-etching the (111) plane and by etching from the back surface. In the above manufacturing method, the insulating film 28 may be a thermal oxide film, CVDSiO ₂ , CVDSi ₃ N ₄ , or a multilayer film thereof.

FIGS. 5A to 5C are views for explaining the outline of the operation of the torsion bar type optical deflector shown in FIG. Also in these figures, for simplicity,
The hatching indicating the cross section is omitted.

That is, as shown in FIG. 5A, the first electrode 29a, the second electrode 29b,
When both the third electrode 29c and the third electrode 29c are grounded, the light 34 vertically incident on the optical deflector is vertically reflected by the reflection surface 35 formed on the surface of the third electrode 29c.

When a negative voltage is applied to the first electrode 29a by the voltage control circuit 32 and the second electrode 29b and the third electrode 29c are grounded as shown in FIG. 5B, the first electrode 29a (P ⁺⁺ buried layer 25a) and third electrode 29c
The electrostatic attraction acts between them, and the torsion bar tilts to the lower right in the figure. At this time, the reflecting surface 35 is tilted by θ _i , and the light 34 that is vertically incident on the optical deflector is reflected at a reflection angle θ _r (= θ _i ), and the incident light is deflected by 2θ _i .

As shown in FIG. 5C, when the first electrode 29a and the third electrode 29c are grounded by the voltage control circuit 32 and a negative voltage is applied to the second electrode 29b, the torsion bar becomes Tilt to the lower left inside. At this time, the reflection surface 35 becomes θ
inclination _i by incident light in the same manner as 34 is deflected by 2 [Theta] _i. Here, the angle of the reflecting mirror can be changed by changing the magnitude of the negative voltage applied to the first electrode 29a and the second electrode 29b.

Also, by alternately switching the negative voltage applied to the first electrode 29a and the second electrode 29b, the reflecting mirror can be used as shown in FIG.
(B) and the state shown in (C) of the same figure can be continuously vibrated. In particular, by setting the frequency of the applied voltage to the resonance frequency of the torsion bar, a large deflection is obtained. The reflector can be vibrated at the corner. Here, the applied voltage may be any of a rectangular wave and a sine wave. However, the voltage control circuit 32
It is necessary to control the applied voltage. That is, optical scanning can be performed by controlling the states shown in FIGS. 5A to 5C as appropriate.

FIGS. 6A and 6B show the second embodiment of the present invention.
FIG. 9 is a plan view and a cross-sectional view showing another configuration of the optical deflector usable as the embodiment in the optical scanning device of FIG. 1. FIG.
In (B), hatching indicating a cross section is omitted for simplification of the drawing.

In this optical deflector, a second silicon substrate is directly bonded to a first silicon substrate on which a polycrystalline silicon film and an insulating film are formed, and a torsion bar serving as a reflecting mirror is formed by anisotropic etching. It is characterized by doing.

That is, in these figures, reference numeral 22 denotes a high-concentration p-type silicon substrate (impurity concentration of 7 × 10 ¹⁹ cm ^-3 or more).
Alternatively, it is a p-type silicon substrate having a p-type diffusion layer of 7 × 10 ¹⁹ cm ⁻³ or more on the surface. 36 is an n-type or p-type silicon epitaxial layer, 37 is a thermal oxide film, 38 is a silicon nitride (Si ₃ N ₄ ) film, 39 is crystalline silicon,
0 (40a, 40b, 40c) and 41 are Au / Cr metal films. Note that the crystalline silicon 39 preferably has an impurity concentration as low as possible, and has an impurity concentration of 10 ¹⁴ cm ⁻³ or less. First silicon substrate 22, second silicon substrate 39
In both cases, the crystal plane is the (100) plane, and the <110>
Laminated in the same direction.

The reflecting mirror is the Au / Cr surface 41 formed on the silicon 39 of the torsion bar, and the Au / Cr metal film 4
0a and 40b function as a first electrode and a second electrode, respectively, and serve as a p-type silicon substrate 22 (Au / Cr metal film 40).
c) becomes the third electrode.

The conditions for changing the angle of the reflecting mirror are as follows: the silicon substrate 22 serving as the third electrode is grounded and the first electrode 40
The first condition that a positive or negative voltage (the second electrode 40b is grounded) is applied to a, and the positive or negative voltage (the first electrode 40a is grounded) is applied to the second electrode 40b. There are two cases of the second condition. Under the first condition, the reflecting mirror tilts to the lower left in the figure, and under the second condition, the reflecting mirror tilts to the lower right. These voltage application controls are performed by the voltage control circuit 32. As described above, by appropriately controlling the application conditions, optical scanning can be performed.

FIGS. 7A to 7K are cross-sectional views for explaining a method of manufacturing the optical deflector of FIG. 6, and also in these figures, hatching showing a cross section for simplification. Is partially omitted.

In FIG. 7A, reference numeral 22 denotes a high concentration p.
A p-type silicon substrate (first silicon substrate) having a high-concentration p-type diffusion layer. Reference numeral 36 denotes an n-type or p-type epitaxial layer grown on the first silicon substrate 22 (hereinafter, the first silicon substrate including the epitaxial layer 36 is referred to as a first substrate).

Next, as shown in FIG. 7B, polycrystalline silicon 42 is deposited on the first substrate 22 to a thickness of about 2,000 Å, and 500 μm of SiO ₂ 43 is formed on the surface of the polycrystalline silicon 42 by thermal oxidation. A film of about Å is formed, and Si ₃ N ₄ 44 is deposited thereon to a thickness of about 1000 Å.

Next, as shown in (C) of FIG. _{7, Si 3 N 4 44,} SiO 2 43 by photolithography, the polysilicon 42 are sequentially etched, reference number 45 in FIG. 6 (A) Is formed. The directions of the four sides of the rectangular pattern 45 are <110> directions.

Next, as shown in FIG. 7D, SiO ₂ 37 is formed by thermal oxidation on the first silicon substrate other than that covered with Si ₃ N ₄ 44 by selective oxidation. The thickness of the thermal oxide film 37 is selected so that the surface of the thermal oxide film 37 has substantially the same height as that of the thermal oxide film 43 (a difference of several hundred angstroms or less). Next, as shown in FIG. 7E, the Si ₃ N ₄ 44 is removed, and S
i ₃ N ₄ 38 is deposited on the order of 3000 angstroms.

Next, as shown in FIG. 7F, the Si ₃ N ₄ 38 is etched by photolithography to support the region without the polycrystalline silicon 42 and the second silicon substrate 39 forming the torsion bar. And Si ₃
Leave N ₄ 38.

Next, as shown in FIG. 7G, the second silicon substrate 39 having the crystal plane (100) is moved to the <110> direction of the second silicon substrate 39 and to the first silicon substrate 22.
Then, they are bonded by heat treatment or anodic bonding. Second
After the silicon substrate 39 is polished to a thickness of about several μm to about 10 μm, an insulating film 37 such as a thermal oxide film or a deposited oxide film is formed.
To form Then, an Au / Cr metal film 40 is deposited on the insulating film 37 and on the back surface of the first silicon substrate 22.

Next, as shown in FIG. 7H, the Au / Cr metal film 40 on the insulating film 37 is subjected to photolithography by reference numerals 40a, 40b, and 4 in FIG.
A pattern is formed as shown in FIG. Subsequently, a pattern of SiO ₂ 37 is formed in the shape of the reflector of the torsion bar (the shape of reference numeral 46 in FIG. 6A). Next, as shown in FIG. 7I, the second silicon substrate 39 is etched with a silicon anisotropic etchant using the insulating film 37 as a mask. Next, as shown in (J) of FIG. 7, Si ₃ N
_{Using the} 438 as a mask, the SiO ₂ 43 is removed by etching to expose the polycrystalline silicon.

Then, as shown in FIG. 7K, the polycrystalline silicon 42 and the underlying epitaxial layer 36 of the first substrate are etched with a silicon anisotropic etching solution. Since the polycrystalline silicon 42 is etched much faster than the crystalline silicon, the side edges advance rapidly,
The (100) surface of the underlying epitaxial layer 36 is exposed, and anisotropic etching of the epitaxial layer 36 starts. Since the polycrystalline silicon 42 is patterned in the <110> direction, the (111) plane 47 is exposed during the anisotropic etching of the epitaxial layer 36, and the etching apparently stops at this plane. When the epitaxial layer 36 is removed to expose the p ++ substrate 22, the substrate impurity concentration becomes 7%.
Etching does not proceed any further since it is set to × 10 ¹⁹ cm ⁻³ or more.

In the above manufacturing method, the lower portion of the second silicon substrate 39 constituting the torsion bar becomes the (100) plane in the anisotropic etching step of the epitaxial layer 36 shown in FIG. 7H. The second with this anisotropic etching
There is a risk that the silicon substrate 39 is etched from the back side. In order to prevent this, for example, when the first substrate 22 and the second substrate 39 are directly bonded in the process shown in FIG. 7G, the two substrates are bonded together with the thermal oxide film formed on the surface of the second substrate. After the second substrate 39 is etched in the anisotropic etching step shown in FIG. 7H, the removal of the thermal oxide film in the step shown in FIG. 7I is performed by dry etching such as RIE. Then, a part of the process may be changed so that the polysilicon 42 is exposed while the thermal oxide film attached to the lower portion 48 of the second substrate 39 is protected.

In the present embodiment, the Au / Cr surface 41 formed on the second silicon substrate 39 of the torsion bar is used as a reflecting mirror. Au / Cr surface 40a, 4
0b can be used as a reflecting mirror.

Further, the inclined surface on the side surface of the second silicon substrate 39 can be used as a reflecting mirror. FIG. 8 is a diagram showing a configuration of a bar code reader to which an optical scanning device using such an optical deflector is applied as a third embodiment of the present invention.

That is, in the same figure, 22 is a silicon substrate on which a waveguide 49 is formed, and 11 is a semiconductor laser as a laser device. This semiconductor laser 11 is arranged in a concave portion formed in the silicon substrate 22, and its laser active layer is aligned with the waveguide layer of the waveguide 49. 1
3 is a laser beam propagating through the waveguide 49, 12 is a waveguide type device as a light focusing element having a condensing / collimating function, 14 is a laser beam narrowed down to a few μmφ, and 15 is the above-mentioned light deflecting emitter A side reflection type optical deflector utilizing the second embodiment, 16 is a deflected laser beam, 17 is a barcode as an object, 18 is reflected light from a barcode, and 19 is a condenser lens as a condenser. , 20 are condensed laser beams, and 21 is a light detection line sensor as a photodetector.

In the third embodiment, the semiconductor laser 11,
Optical waveguide 49, waveguide device 12, optical deflector 1
5. The light detection line sensor 21 is the same silicon substrate 2
Since they are integrated on the substrate 2, further miniaturization, simplification of assembly, and higher precision can be achieved.

FIGS. 9A to 9C show a fourth embodiment of the present invention.
FIG. 14 is a view showing an embodiment, and shows a configuration of a light emitting device as another light deflector in place of the light deflector of the third embodiment.
The fourth embodiment is characterized in that it has a waveguide structure and is provided with a cantilever having a grating for emission.

That is, 22 is a p ⁺⁺ silicon substrate and 50 is n
A type or p-type silicon epitaxial layer 51 is a cantilever having a waveguide structure. The structure of the waveguide is
As shown in FIG. 9B, a multilayer structure of a buffer layer 53, a first cladding layer 54, a waveguide layer 55, a second cladding layer 56, a buffer layer 57, and a metal layer 58 is formed on a substrate 52. The uppermost metal film 58 is composed of the cantilever 51 and the substrate 2.
2 (electrode 40c) is an electrode for applying a voltage between them.

Numeral 12 denotes a Fresnel lens as a light focusing element, which has a function of collimating light incident on the waveguide layer 55 from the semiconductor laser 11 by end face coupling. The parallel laser light 14 is emitted in a vertical or oblique direction by the condensing grating 59 on the cantilever 51 and condensed in space.

In the region where the grating 59 is formed, the metal layer 58 is removed in order to prevent light absorption. That is, the grating 59 is formed in the window 60 from which the metal layer 58 has been removed. Grating 5
9 is formed between the waveguide layer 55 and the second cladding layer 56. Further, on the back surface of the cantilever 51, a p ⁺⁺ layer 6 is provided as a support so that 59 parts of the grating are not displaced.
1 is provided.

The cantilever 51 has a resonance frequency determined by the material constituting the cantilever 51, its length, its thickness, and the like.
As shown in FIGS. 9B and 9C, an AC voltage 62 is applied between the metal layer 58 and the substrate 22 (electrode 40c), the cantilever 51 is excited by electrostatic attraction, and the excitation frequency is changed to the cantilever. By setting it near the resonance frequency of 51, a large vibration displacement can be obtained. However, AC voltage 62
Is controlled by the voltage control circuit in the same manner as the other embodiments described above so that a smooth scan can be performed.

In the method of manufacturing the light emitting device having such a structure, first, the cantilever 51 is formed in the same manner as the manufacturing of the torsion bar in the first embodiment (however, the anisotropic etching is performed on the substrate surface). Only from Thereafter, after forming a high-refractive-index Si ₃ N ₄ layer on the waveguide layer 55, the second cladding layer 56 and subsequent layers are deposited after the processing steps of the Fresnel lens 12 and the grating 59. FIGS. 10A to 10C are diagrams showing still another configuration of a light deflection / emission device that can be used in the optical scanning device having the configuration of FIG. 1 as a fifth embodiment of the present invention.

In the fifth embodiment, the shape memory alloy 63 and the thin film heater 64 are integrated on a torsion bar, and the thin film heater 64 is energized to heat the shape memory alloy 63 to cause a change in shape. Light is deflected and emitted.

That is, in these figures, 22 is a substrate,
65 is an insulating film, 63 is a shape memory alloy, and 64 is a thin film heater. It is assumed that the shape memory alloy 63 and the thin film heater 64 are insulated (not shown in the figure). Shape memory alloy 63
Are connected to the substrate 22 by an insulating film 65.

FIG. 10B shows a state in which the thin film heater 64 is not energized. The shape memory alloy 63 is flat, and the light 66 perpendicularly incident on the optical deflector is reflected without being deflected. You.

FIG. 10C shows a state in which the thin film heater 64 is energized to heat the shape memory alloy 63. At this time, the shape memory alloy 63 is curved. At this time, the light 66 vertically incident on the optical deflector is deflected in a direction indicated by reference numeral 67 in the figure according to the curvature of the shape memory alloy 63. Therefore, optical scanning can be performed by repeating the states shown in FIGS. 10B and 10C.

FIGS. 11A to 11D show a sixth embodiment of the present invention, which shows still another configuration of the light deflection / emission device that can be used in the optical scanning device having the configuration shown in FIG. In the sixth embodiment, a conductive elastic body is vibrated by electrostatic power,
The light is deflected by changing the curvature of the reflecting mirror.

In these figures, reference numeral 22 denotes a high-concentration p-type substrate, 68 denotes an n-type or p-type epitaxial layer, 69 denotes an insulating elastic body, and 70 denotes a conductive elastic body. You may use it. The conductive elastic body (hereinafter referred to as a metal thin film) 70 is processed into a shape of a beam bridged over the substrate 22 having the concave portion, and an insulating elastic body 69 is provided below the metal thin film 70.

An AC voltage 71 is applied between the metal thin film 70 and the p ⁺⁺ substrate 22 to vibrate the elastic body on the substrate recess 72 by electrostatic attraction. Exciting at the resonance frequency of the beam, which is determined by the material of the elastic body and its thickness, length, etc., makes it possible to give a large displacement to the elastic body. FIG. 11B shows a state in which the elastic body is flat and the light 73 vertically incident on the optical deflector is reflected without being deflected.

FIGS. 11C and 11D show the state in which the elastic body is displaced downward and upward, respectively, and the incident light 73 is directed in the directions indicated by reference numerals 74 and 75, respectively. Is reflected by Optical scanning can be performed by repeating the states shown in FIGS. 11C and 11D.
In this case, of course, the AC voltage 71 is controlled by a voltage control circuit (not shown).

FIGS. 12A to 12C are diagrams showing still another configuration of an optical deflection / emission device which can be used in the optical scanning device having the configuration of FIG. 1 as a seventh embodiment of the present invention. In the seventh embodiment, optical scanning is performed using the electrostrictive effect of a ferroelectric substance.

FIG. 12A is an external view of the present optical deflector, and FIGS. 12B and 12C are sectional views taken along line BB. Reference numeral 22 denotes a silicon substrate having a crystal plane (100), reference numeral 76 denotes an insulating film, reference numeral 77 denotes a ferroelectric, and reference numeral 78 denotes a comb-shaped electrode for driving the ferroelectric 77.

The ferroelectric substance 77 is connected to the substrate 22 via the insulating film 76, and the lead from the comb-shaped electrode 78 passes through the insulating film and is connected to the contact pad 79 on the substrate. By applying an AC voltage 80 to the comb-shaped electrode 78, a compressive stress is applied to the ferroelectric 77 in the lateral direction, and a contraction force acts. By setting the drive voltage to the resonance frequency of the torsion bar, a large curve can be generated in the torsion bar. As shown in FIGS. In the direction of. Of course, as in the other embodiments described above, the AC voltage 80 is controlled by a voltage control circuit (not shown). In addition, various types of light deflection / emission devices using micromachining can be applied to the present invention.

[0073]

As described in detail above, according to the present invention,
Since the light deflection emitter is manufactured by silicon micromachining, the size and weight of the optical scanning device using the light deflection emitter can be reduced, and the light deflection emitter and the photodetector are integrated on the same semiconductor substrate. When the optical scanning device of the invention is applied to configure an optical device such as a bar code reader, it is possible to achieve a reduction in the number of components, ease of assembly, miniaturization of the whole, and high detection accuracy.

Further, by using a semiconductor laser as a light source and introducing light into the optical waveguide by end face coupling, a light-collecting collimating function can be performed by a waveguide type device, and the light is emitted after being deflected on the silicon substrate on which the waveguide is formed. Since the light reflected from the barcode can be received by the photodetector formed on the same silicon substrate, many components of the barcode reader system can be made monolithic.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a barcode reader to which an optical scanning device according to a first embodiment of the present invention is applied.

FIG. 2 is a block diagram of the bar code reader of FIG. 1;

FIGS. 3 (A) to 3 (C) each show an electrostatically driven torsion bar type light as a minute light deflection / emission device manufactured by micromachining which is used in the optical scanning device of the first embodiment. It is a figure which shows the structure of a deflector, (A) is a top view,
(B) and (C) are respectively the BB line and C in (A).
FIG. 4 is a sectional view taken along line C of FIG.

FIGS. 4A to 4F are cross-sectional views for explaining an outline of a method of manufacturing the electrostatic drive torsion bar type optical deflector in the first embodiment.

FIGS. 5A to 5C are diagrams for explaining the outline of the operation of the torsion bar type optical deflector in the first embodiment.

FIGS. 6A and 6B are a plan view and a sectional view showing another configuration of an optical deflector which can be used in the optical scanning device of FIG. 1 as a second embodiment of the present invention.

FIGS. 7A to 7K are cross-sectional views for explaining a method of manufacturing an optical deflector according to a second embodiment.

FIG. 8 is a perspective view showing a configuration of a bar code reader to which an optical scanning device using an optical deflector according to a second embodiment is applied as a third embodiment of the present invention.

FIGS. 9A to 9C are views showing a fourth embodiment of the present invention. FIG. 9A is a perspective view showing a configuration of a light emitting device as a light deflecting light emitting device, and FIG. (C) and (C) are cross-sectional views for explaining the operation.

10 (A) to 10 (C) are views showing a fifth embodiment of the present invention, and FIG. 10 (A) shows still another light deflection / emission device which can be used in the optical scanning device having the configuration of FIG. It is a figure which shows a structure, (B) and (C) are sectional views for demonstrating operation | movement, respectively.

FIGS. 11A to 11D are views showing a sixth embodiment of the present invention. FIG. 11A shows still another light deflection / emission device that can be used in the optical scanning device having the configuration shown in FIG. It is a figure which shows a structure, (B) thru | or (D) are sectional drawings for demonstrating operation | movement, respectively.

12 (A) to 12 (C) are views showing a seventh embodiment of the present invention, and FIG. 12 (A) is still another light deflection / emission device which can be used in the optical scanning device having the configuration of FIG. It is a figure which shows a structure, (B) and (C) are sectional views for demonstrating operation | movement, respectively.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Laser apparatus, 12 ... Light focusing element, 15 ... Light deflecting / emitting device, 17 ... Barcode, 19 ... Condensing element, 21 ... Photodetector, 22 ... Silicon substrate.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/04-1/207 G02B 26/00-26/12 G06K ⁷ /00-7/14

Claims (7)

(57) [Claims] 1. An optical scanning apparatus comprising: a light source; a light deflecting / emitting section for deflecting and emitting light from the light source to scan a subject; and a photodetector for detecting reflected light from the subject. An optical scanning device, wherein at least the light deflector and the light detector are integrally formed on the same semiconductor substrate. 2. The optical scanning device according to claim 1, wherein the light deflection emission unit includes a torsion bar formed in a concave portion of the semiconductor substrate, and a pair of electrodes facing the torsion bar. 3. The light deflecting and emitting section includes a torsion bar formed in a concave portion of the semiconductor substrate, a pair of electrodes formed on the torsion bar, and an electrode facing the torsion bar. The optical scanning device according to claim 1, wherein: 4. The optical scanning device according to claim 1, wherein the light deflection emission unit includes a cantilever having a waveguide and a grating. 5. The optical scanning device according to claim 1, wherein the light deflection emission unit is a torsion bar including a shape memory alloy and a thin film heater. 6. The light deflecting and emitting section includes a torsion bar having conductivity and reflectivity formed in a concave portion of the semiconductor substrate, and an electrode facing the torsion bar. The optical scanning device according to claim 1. 7. The light deflecting and emitting section includes a torsion bar formed in a concave portion of the semiconductor substrate, a ferroelectric formed on the torsion bar, and a comb-shaped electrode formed on the ferroelectric. 2. The optical scanning device according to claim 1, comprising: