JPH10253912A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an optical scanner, to reduce dispersion in operational characteristic in such a case, to enhance the positional precision of a mirror, to warrant vibration opeartion of a vibration part and to prevent the operational characteristic from changing due to an external cause. SOLUTION: A thin part is formed on a silicon substrate 1, and movable parts 12-16 such as a mirror part 12, etc., are formed on this thin part, and the movable parts 12-16 are driven by piezoelectric body films 21-24. By this driving, the mirror part 12 is twisted and vibrated in the different axial directions. A metal thin film is formed on the mirror part 12, and by making light incident on this metal thin film, two-dimensional light scanning is performed.

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 which can be used for a laser printer, a bar code reader, and the like.

[0002]

2. Description of the Related Art Conventionally, as this kind of optical scanning device, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 7-199099. FIG. 19 shows a configuration of the optical scanning device, and FIG. 20 shows an operation state thereof. The optical scanning device 100 includes a thin plate 101.
And four piezoelectric bimorphs (vibration means) 121 to 124 installed at both upper and lower ends of the plate 101.

The plate 101 is formed by processing a thin metal plate into a shape as shown in FIG. Near the center of the plate 101, there is formed a mirror installation part 111 to which a mirror provided with a high reflection coating (Al evaporation, Au evaporation, etc.) is adhered.
A mirror is adhered onto the mirror installation section 111 to form the mirror section 102.

A pair of first spring portions (first torsional vibrating portions) 114 are provided at opposite ends of the mirror installation portion 111.
Are formed. In addition, the mirror installation unit 111
The first frame portion (first holding portion) 116 formed outside the mirror installation portion 111 by the spring portion 114
As shown in FIG. 20, it is rotatable around the j-axis.

[0005] The first frame portion 116 is formed by a pair of second spring portions (second torsional vibrating portions) 113 into a first frame portion.
It is supported by a second frame portion (second holding portion) 115 formed outside the frame portion 116, and has a rotation axis k perpendicular to the rotation axis j of the first spring portion 114 as a center axis. It is rotatable. Second frame part 11
5 is a second frame 1 by a pair of connecting portions 117.
It is supported by a third frame portion 112 formed outside the reference numeral 15 and is rotatable about a vibration axis i of the connecting portion 117 as a central axis. As shown in FIG. 20, the vibration axis i is an axis formed in a direction deviated by 45 ° from the rotation axis j and the rotation axis k, respectively.

Further, piezoelectric bimorphs 121 to 124 as driving sources are adhered to both upper and lower ends of a third frame 112 formed on the plate 101. The above-described optical scanning device 100 operates as follows.
In FIG. 20, the optical scanning device 100 includes one ends a, b, of the piezoelectric bimorphs 121 to 124 as driving sources.
C and d are fixed ends, and the other end is a free end, and is fixed to a substrate or the like (not shown) for constructing an optical system. Also, the piezoelectric bimorphs 121 to 124
The bonding is performed in consideration of the polarization direction of the piezoelectric element.

When the same sine wave signal is applied to each of the piezoelectric bimorphs 121 to 124, each of the piezoelectric bimorphs performs bending vibration as shown in FIG. That is, the piezoelectric bimorphs 121, 122 and 123
And 124 perform bending vibrations of the same phase, respectively, and the piezoelectric bimorphs 121 and 123 and 122 and 124 perform bending vibrations of the opposite phases. This vibration is converted into torsional vibration centered on the i-axis of the second frame 115 by passing through the connecting portion 117.

Here, the mirror section 102 and the first frame section 116 are connected by a first spring section 114, and the combination of the first spring section 114 and the first spring section 114.
The torsional vibrator is configured with the j-axis corresponding to the axis as a rotation axis. Further, the first frame part 116 and the second frame part 115 are connected by a second spring part 113, and the combination thereof is the same as the second spring part 1
A torsional vibrator is constituted by using a k-axis corresponding to thirteen axes as a rotation axis. Therefore, the mirror unit 102 can perform torsional vibration with the j axis and the k axis as rotation axes, and constitute a vibration system having two degrees of freedom.

Therefore, the first spring portion 114 and the second spring portion 11 are formed by the piezoelectric bimorphs 121 to 124.
When a periodic external force acts on the first spring portion 1,
14 is twisted when the periodic external force is applied, generates a rotation torque in a direction corresponding to the rotation angle of the torsion, and in a direction opposite to the direction of the torsion. Is forcedly vibrated. The second spring portion 113 is also twisted when the above-described periodic external force is applied, and generates a rotation torque in a direction corresponding to the rotation angle of the torsion with a magnitude corresponding to the rotation angle of the torsion. Then, the mirror unit 102 is forcibly vibrated via the first frame unit 116.

The above-described optical scanning device 100 can be applied to an optical information reading device such as a bar code reader. FIG. 21 shows the configuration. A driving circuit for driving the optical scanning device 100 includes a generator 131 for generating a sine wave signal having an angular frequency ωj, a generator 132 for generating a sine wave signal having an angular frequency ωk, and the signal generators 131 and 132. Adder 133 for adding the obtained sine wave signal;
Amplifying circuit 134 for amplifying the signal generated in step 3 and a signal output from this amplifying circuit 134
1 to 124.

When a driving signal output from the amplifier circuit 134 is applied to the piezoelectric bimorphs 121 to 124, the second frame 115, the second spring 113,
The first frame part 116, the first spring part 114, and the mirror part 102 perform torsional vibration as a whole with the i-axis as a rotation axis. At this time, since the mirror section 102 has a moment of inertia, it receives a torsional moment about the i-axis and acts as an exciting force in the torsional direction. And
The torsional excitation force is caused by the two-degree-of-freedom torsional vibrator described above, that is, the torsional vibration of the mirror section 102 around the j-axis and the torsional vibration around the k-axis. And act as a vibrating force to cause the mirror portion 102 to torsional vibration.

The laser drive circuit 135 generates a laser beam from the laser diode 136. The laser light generated by the laser diode 136 is reflected by the torsionally vibrating mirror section 102, is deflected by twice the torsion angle of the mirror section 102, and scans the barcode label 137 with light. Then, the light scattered on the barcode label 137 is received by the light receiving element 138, and is converted into an electric signal according to the light intensity of the received scattered light. Then, the obtained electric signal is converted into a binary signal by the binarization circuit 139, and the decoding circuit 140 performs a decoding process according to the contents of the barcode symbol.

Incidentally, the piezoelectric bimorphs 121 to 124 which are the driving sources described above may have a piezoelectric unimorph structure bonded to only one surface of the third frame 112.

[0014]

The present inventors have studied the miniaturization of the above-mentioned conventional structure, and found that there are the following problems. First, since the plate 101 is formed of a thin metal plate, there is a problem that as the size of the plate 101 is reduced, the operating characteristics are likely to vary due to the processing accuracy.

Second, since the mirror is adhered on the mirror mounting portion 111 of the thin metal plate 101, the positional accuracy becomes a problem. Third, as the size is reduced, torsional vibration of the mirror unit 102 and the like is less likely to occur due to the viscosity of air, and in the worst case, a state in which the mirror unit 102 does not operate at all occurs. In addition, there is a problem that operating characteristics change due to external factors in the operating environment.

The present invention has been made in view of the above problems, and a first object of the present invention is to reduce variations in operating characteristics even when the size is reduced. A second object is to improve the positional accuracy of the mirror. It is a third object of the present invention to guarantee the vibrating operation of the vibrating portion even when the size is reduced, and to prevent the operation characteristics from changing due to external factors in the operating environment.

[0017]

To achieve the above object, according to the first aspect of the present invention, there is provided a semiconductor substrate (1) having a thin portion (2) formed thereon, and a vibrating means for vibrating the thin portion. (21-24), and the light emitting portion (10) for emitting light is provided in the thin portion.

Therefore, a thin portion is formed on the semiconductor substrate,
By causing it to vibrate, variations in operating characteristics can be reduced. Further, when the mirror is formed by using the metal thin film (10) as in the second aspect of the present invention, light scanning can be performed by light reflection, and the position accuracy of the mirror can be improved by using a semiconductor process. Can be increased.

In this case, the mirror section (12) on which the metal thin film is formed is different from the mirror section (2).
By vibrating about the axis as a rotation axis, two-dimensional optical scanning can be performed. Further, as in the invention according to claim 4, a monitor means (63a, 63b, 64a, 6a) for monitoring the vibration of the mirror section having two different axes as rotation axes.
4b, 65 to 68), the vibrating means can be appropriately driven by using the monitor output for controlling the driving signal to the vibrating means.

The monitoring means includes a torsional vibrating section (13a, 13b, 14).
a, 14b) The monitoring can be performed based on the torsional state. More specifically, as in the invention according to claim 6, the torsional vibrator has a resistance value due to the stress caused by torsion. Variable resistance (63a, 64
a, 64b, 63b) can be used for monitoring.

The thin portion formed on the semiconductor substrate may be a mirror portion (12) on which a metal thin film is formed and a predetermined gap from the mirror portion. The first holding portion (16) formed in this way is connected to the mirror portion and the first holding portion and twisted when a periodic external force is applied, and twisted with a magnitude corresponding to the rotation angle of the twist. The first torsional vibrator (14, 14) forcibly vibrates the mirror so that a rotational torque is generated in a direction opposite to the direction of
14a, 14b), a second holding part (15) formed through a predetermined gap with respect to the first holding part, and the first holding part and the second holding part are connected to each other. Is twisted when an external force is applied, and the mirror section is forcibly vibrated through the first holding section so that a rotation torque is generated in a direction corresponding to the rotation angle of the twist in a direction opposite to the direction of the twist. Second
And the torsional vibrating portions (13, 13a, 13b).

In this case, the above-described periodic external force is applied to each of the first and second torsional vibrating portions by the vibrating means. In the invention according to claim 8,
It is characterized in that a through hole (50) is formed in the mirror portion, and light is reflected from the metal thin film through the through hole.

In this case, light can be reflected from the back surface of the metal thin film. In addition, as the above-described vibration means, a piezoelectric element (21 to 24) formed on a thin-walled supporting portion can be used. In the invention according to claim 10, the thin portion (2) is formed of a member (1) in which at least the light emission direction is transparent.
1, 41) is characterized by being airtightly covered.

With such a configuration, the vibration operation of the thin-walled portion can be ensured even when the size is reduced, and the operation characteristics can be prevented from being changed by an external factor in the operation environment. The reference numerals in parentheses described in the claims and the means for solving the problem indicate the correspondence with specific means described in the embodiments described later.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows an overall configuration diagram of a two-dimensional optical scanning device according to a first embodiment of the present invention, and FIG. 2 shows a cross section taken along line AA in FIG. A thin portion 2 is formed on the silicon substrate 1 by etching from the back surface as shown in FIG. A through groove 3 is formed in the thin portion 2,
Due to the formation of this through groove 3, the thin portion 2 is
2. First spring portion (first torsional vibrating portion) 14, first frame portion 16 (first holding portion), second spring portion 13 (second torsional vibrating portion), second frame portion (second torsional vibrating portion). Holding part) 15 and other movable parts. These are the mirror part 102, the first spring part 114, the first frame part 116, and the second spring part 11 shown in FIG.
3. It has the same function as the second frame 115 and performs the same operation.

The thin portion 2 has a cantilever structure, and a piezoelectric film 21 to 24 of PZT or the like is formed on a support portion thereof. The piezoelectric films 21 to 24 have a piezoelectric unimorph structure, and the piezoelectric bimorph 12 shown in FIG.
It has a function equivalent to that of 1-124 and performs an equivalent operation, and constitutes a vibrating means for vibrating the thin portion 2. When the present embodiment is applied to the optical information reading apparatus as shown in FIG. 21, a drive signal from the amplifier circuit 134 shown in FIG. 21 is applied to the piezoelectric films 21 to 24.

On the silicon substrate 1, a bonding pad 4 and a substrate electrode 5 are formed. Each bonding pad 4 is electrically connected to the upper electrode 7 of the piezoelectric films 21 to 24 via the wiring 6. Also, the piezoelectric films 21 to 24
Are formed on the lower electrode 8 as shown in FIG. The silicon substrate 1 has a low resistance layer 9
(Shown by a dotted line in FIG. 1), and the substrate electrode 5 and the lower electrode 8 are electrically connected by the low resistance layer 9. The mirror section 12 is provided with a mirror 10 constituting a reflection surface. In addition, the bonding pad 4,
The substrate electrode 5, the wiring 6, the upper electrode 7, and the mirror 10 are formed of a metal thin film such as aluminum.

On the lower side of the silicon substrate 1, glass as a base, for example, borosilicate glass (trade name: Pyrex glass) 11 is bonded by an anodic bonding method. The Pyrex glass 11 is fixed to a case (not shown) by soldering or the like. By providing the Pyrex glass 11, it is possible to improve the handleability at the time of assembly and to reduce the thermal stress from the case.

In the above configuration, when a drive signal is applied to the bonding pad 4 and the substrate electrode 5, the piezoelectric film 2
1 to 24 cause the mirror section 12 to torsionally vibrate under a predetermined resonance condition. This torsional vibration operation is the same as that shown in FIG. Therefore, when light is incident on the mirror 10 that performs torsional vibration, two-dimensional scanning can be performed using the reflected light.

Next, the method of manufacturing the above optical scanning device will be described.
This will be described with reference to FIGS. 3 and FIG.
The same cross-sectional state as FIG. 2 is shown. First, the plane orientation (10
3), an insulating film 31 such as SiO ₂ is formed on both surfaces of the n-type silicon substrate 1 by thermal oxidation (FIG. 3).
(A)). Next, a predetermined position of the insulating film 31 is removed, and a p-type impurity is introduced by ion implantation, solid phase diffusion, or the like to form the low resistance layer 9 (FIG. 3B). Then, the insulating film 31
Is removed, and SiO _{2 is} again applied to both surfaces of the silicon substrate 1.
An insulating film 32 is formed (FIG. 3C), and then a predetermined position of the insulating film 32 is removed (FIG. 3D).

Then, a lower metal electrode 8 of platinum / titanium or the like is formed by sputtering or electron beam evaporation (FIG. 3E), and thereafter, sputtering, sol-gel method, C
Piezoelectric films 21 to 24 of PZT or the like (the piezoelectric film 23 is shown in the figure) are formed by VD or the like (FIG. 3F).
Next, a thin metal film such as aluminum is formed by sputtering, electron beam evaporation, or the like. This metal thin film becomes the bonding pad 4, the substrate electrode 5, the wiring 6, the upper electrode 7, and the mirror 10 (FIG. 4A). Then, an insulating film 33 such as SiO ₂ is formed on the entire surface by sputtering, CVD, or the like.
Is formed (FIG. 4B).

Thereafter, a predetermined portion of the insulating film 32 on the back surface is removed, and silicon is anisotropically etched to form a thin portion 2 (FIG. 4C). In this case, boron is used as an impurity of the p-type low-resistance layer 9 formed in the step of FIG. 3B, the concentration is set to 5 × 0 ¹⁹ cm ⁻³ or more, and EPW (ethylenediamine-pyrocatechol-
When water is used, the p-type low-resistance layer 9 is hardly etched, so that the thin portion 2 can be formed with good controllability.

Then, the insulating film 3 on the back surface of the silicon substrate 1
2 is removed, the Pyrex glass 11 is bonded by an anodic bonding method (FIG. 4D), and thereafter, a predetermined position 3 of the thin portion 2 is penetrated by dry etching to obtain a structure shown in FIG. (FIG. 4E) is obtained. Second Embodiment FIG. 5 shows a schematic configuration of an optical scanning device according to a second embodiment of the present invention. FIG. 6 shows a BB cross section in FIG.

In the present embodiment, a glass, for example, Pyrex glass 41 is hermetically bonded to the upper portion of the silicon substrate 1 so that the atmosphere in the space 42 in which the movable portion such as the mirror portion 12 is disposed can be controlled. I have. Therefore,
The areas where the thin portions 2 and the piezoelectric films 21 to 24 are formed are hermetically covered by the Pyrex glasses 41 and 11, and the torsional vibration operation of the mirror portion 12 and the like is assured. Changes in properties are prevented.

The insulating film 3 is formed on the surface of the silicon substrate 1.
3 is formed, a silicon thin film 44 is further formed on the insulating film 33 to perform anodic bonding with the Pyrex glass 41. Further, the Pyrex glass 41 is provided with a getter 43 for adsorbing a gas generated during anodic bonding to evacuate the space 42. The getter 43 and the space 42 are connected by a passage 45 formed by etching the silicon thin film 44.

In order to obtain a hermetic joint of the Pyrex glass 41, it is necessary to flatten the surface of the silicon thin film 44. Therefore, the diffusion resistance 6a
Is formed, and the bonding pad 4 is formed via the diffusion resistor 6a.
To the wiring 6. The optical scanning device according to this embodiment can be configured by forming a silicon thin film 31 on an insulating film 33 and anodically bonding Pyrex glass 41 in a vacuum-controlled atmosphere in a final process.

FIG. 7 shows a modification of the above embodiment. In this modification, the Pyrex glass 41 is formed in a flat plate shape, and a silicon spacer substrate 46 is provided in order to secure a space in which movable parts such as the mirror part 12 are arranged.
Is inserted between the Pyrex glass 41 and the silicon substrate 1. The spacer substrate 46 and the Pyrex glass 41 are bonded by an anodic bonding method. Then, the insulating film (SiO ₂ ) 3 on the back surface of the spacer substrate 46 and the silicon surface is formed.
3 is eutectic-bonded to the gold thin film 47 formed thereon.

By adopting such a configuration, it is not necessary to provide a space 42 in the Pyrex glass 41, and the surface through which light passes can be easily made an optically flat surface. (Third Embodiment) FIG. 8 shows a schematic configuration of an optical scanning device according to a third embodiment of the present invention. FIG. 8 is a view of the whole as viewed obliquely from below. FIG.
FIG. FIG. 9 shows the same cross-sectional state as FIG.

This embodiment is different from the embodiments shown in FIGS. 5 and 6 in that a through hole 50 is formed in the silicon substrate 1 in the mirror section 12 as shown in FIG. However, in this embodiment, light is incident from the Pyrex glass 11 on the rear surface side, passes through the through hole 50 and the insulating film 32, and is reflected on the rear surface of the mirror 10.

In this case, the Pyrex glass 11 on the lower side of the silicon substrate 1 has a flat plate shape and does not require processing such as providing a space 42 like the Pyrex glass 41 on the upper side, so that an optically polished surface is obtained. Easy to do.
Therefore, attenuation such as scattering of light passing through the Pyrex glass 11 can be suppressed to a minimum. As described above, when light is incident from the back surface side of the silicon substrate 1,
It is conceivable that a mirror made of a metal thin film is formed on the etched surface of the silicon substrate 1, but the etched surface has a worsened surface roughness than the polished surface, so that the surface cannot be used as a mirror surface as it is. . Affixing a mirror on top of that also causes a variation in assembling and characteristics (resonance frequency), which is also a problem. Accordingly, such a problem can be solved by forming the through-hole 50 as in the present embodiment. (Fourth Embodiment) In the first embodiment shown in FIG.
The driving signal is applied to the bonding pad 4 and the substrate electrode 5 to drive the piezoelectric films 21 to 24 under predetermined resonance conditions. However, in such a resonance driving method, the piezoelectric film 21 to 24 is driven by a change in ambient temperature or the like. Because the resonance frequency changes,
It is preferable to control the drive signal by monitoring the frequency and the amplitude of the drive signal.

For this reason, in this embodiment, two axes (i-axis,
A configuration is provided in which monitoring means for monitoring the vibration of the mirror unit 12 with the (k-axis) as a rotation axis is provided. Specifically, FIG.
As shown in FIG. 1, the low resistance layer 9 in FIG. 1 is divided into two parts to form low resistance layers 9a and 9b (indicated by hatching in FIG. 10), and the low resistance layers 9a and 9b To 24, a part of the first and second frame portions 16 and 15, a first spring portion 14 (shown as reference numerals 14a and 14b in the drawing),
The second spring portion 13 (reference numerals 13a, 13b
), The mirror portion 12 and the outer peripheral portion of the silicon chip. The substrate electrode 5a is connected to the low resistance layer 9a, and the substrate electrode 5b is connected to the low resistance layer 9b. Furthermore, the first and second
The spring parts 14 and 13 are bent (turned)
The first and second spring portions 14 and 13 are applied with a large tensile stress and a large compressive stress in the longitudinal direction when the mirror portion 12 rotationally vibrates.

With such a configuration, the low resistance layers 9a and 9b formed below the first and second spring portions 14a, 14b, 13a and 13b receive the stress when the mirror portion 12 rotates and vibrates. Thus, the resistance is changed, that is, the resistance is changed by the piezoresistance effect of silicon. In this case, the second from the substrate electrode 5a
The frame part 15, the second spring part 13a, the first frame part 16, the first spring part 14a, the mirror part 12, the first spring part 14b, the first frame part 16, the second spring part 13b, and the second frame part 15 Through this, the structure is electrically connected in series up to the substrate electrode 5b. Therefore, the second spring portion 13a, the first spring portion 14a, the spring portion 14b, the second spring portion 1
The variable resistance of the low-resistance layers 9a and 9b formed below the substrate electrode 5a, as shown in FIG.
Variable resistor 63 connected in series between
a, 64a, 64b and 63b.

Then, as shown in FIG.
If a DC power supply (power supply for vibration monitoring) 66 is connected to the power supply a and the substrate electrode 5b is grounded via the reference resistance 65, the variable resistances 63a, 64a, 6
Since the resistance values of 4b and 63b change in synchronization with the frequency of the rotational vibration, the output voltage from the substrate electrode 5b changes accordingly. This output voltage is a voltage having the frequency component of the rotational vibration of the mirror unit 12 with the two axes as the rotation axes.

This output voltage is supplied to the low-pass filter circuit 6
7. Output to the high-pass filter circuit 68. And
Low-pass filter circuit 67, high-pass filter circuit 68
Is set between the respective resonance frequencies of the two-axis rotational vibration, vibration monitor outputs 1 and 2 corresponding to the respective frequency components of the two-axis rotational vibration can be obtained. The vibration monitor outputs 1 and 2 are used by a circuit (not shown) for controlling drive signals to the piezoelectric films 21 to 24.

According to the above configuration, since there is no metal wiring or the like between the movable portion such as the frame portion and the outer peripheral portion, the aerial wiring using a wire or the metal wiring on the spring portion becomes unnecessary. When a wire is used, problems such as securing reliability of connection between the movable part and the fixed part, or fluctuation of the resonance frequency occur. Also, when metal wiring is formed on the spring part, disconnection due to repeated stress, due to residual stress, Although a problem such as a change in resonance frequency occurs, such a problem can be eliminated by eliminating the need for a metal wiring or the like between the movable portion and the outer peripheral portion.

FIG. 12 shows a configuration in which a circuit for driving the piezoelectric films 21 to 24 is provided. Since the potentials of the substrate electrodes 5a and 5b become the potentials of the substrate electrodes of the piezoelectric films 21 to 24, they cannot be grounded as in the first embodiment. For this reason, an AC drive power supply 69 is provided for the piezoelectric films 21 and 23 so that the potential of the substrate electrode 5a becomes the reference potential, and a drive signal is applied to the piezoelectric films 21 and 23 and the piezoelectric films 21 and 23 are driven. For the films 22 and 24, the substrate electrode 5
AC driving power supply 70 so that the potential of
Is provided so that a drive signal is applied to the piezoelectric films 22 and 24. Since the phases of the drive signals applied to the piezoelectric films 21 and 23 and the phases of the drive signals applied to the piezoelectric films 22 and 24 need to be opposite to each other, the phase shift circuits 71 and 72 are provided. I have.

In the above-described configuration, the electric wires in the first and second frame portions 16 and 15 are connected to the low resistance layer 9a,
Although the structure formed by 9b is shown, as shown in FIG.
In this case, a voltage drop in portions other than the spring portion can be suppressed. Since the upper portions of the first and second frame portions 16 and 15 are hardly deformed, no stress is applied to the metal wiring 25 formed thereon, and no disconnection or the like occurs. Further, if the metal wiring 25 is formed by the same process as that of the mirror section 10, it can be dealt with only by changing the mask. In addition, if the outer periphery of the silicon chip is also routed by the metal wiring 26, the wiring resistance is reduced, so that the piezoelectric films 21 to
The voltage applied to the mirror 24 can be prevented from causing a difference, and the vibration of the mirror unit 10 can be improved.

Further, as shown in FIG.
Can be formed on the same silicon chip. In this case, if the reference resistance 65 is a resistance layer formed in the same step as the low resistance layers 9a and 9b, the reference resistance 65 can be formed without increasing the number of steps, and the reference resistance 65 and the variable resistance 63a, Since the temperature characteristics of 64a, 64b, and 63b can be equalized, the temperature characteristics of the monitor output voltage can be improved.

Next, a method of manufacturing the optical scanning device shown in FIG. 10 will be described. In this embodiment, as described above, since the resistance change due to the piezo effect of silicon is used, the spring portions 13a, 13b, 14a, 1
4b becomes important. For example, the plane orientation of the silicon substrate is (100), the conductivity type is n-type, the low-resistance layer 9a,
When 9b is p-type, the piezoresistive coefficient of p-type silicon is maximum in the <110> direction, so that the longitudinal direction of the spring portions 13a, 13b, 14a, 14b is <110>.
If it is installed so as to be> direction, the maximum resistance value change can be obtained. However, the spring parts 13a, 13b,
When the longitudinal directions of 14a and 14b are arranged in the <110> direction, the rectangle formed by etching from the back surface is inclined by 45 ° with respect to the outer periphery of the silicon chip as shown in FIG. The support portions 24 are also inclined by 45 ° from the longitudinal direction, and it is impossible to obtain an ideal vibration. In addition, the chip area increases.

Therefore, in this embodiment, the optical scanning device is manufactured using the SOI substrate. The manufacturing method in this case will be described with reference to FIGS. The process diagrams in FIGS. 16 and 17 correspond to FIGS. 3 and 4, and therefore, the present manufacturing method will be described in relation thereto. First, an SOI substrate 1 is prepared.
In this SOI substrate 1, an insulating film 1a made of silicon oxide or the like is embedded, and the SOI portion 1b has a (100) plane orientation and an n-type conductivity. The conductivity type of the substrate 1c may be either p-type or n-type. And SO
An insulating film 31 is formed on both surfaces of the I substrate 1 (FIG. 16).
(A)).

Thereafter, a predetermined position of the insulating film 31 is removed,
The p-type low-resistance layers 9 (9a, 9b) are formed in the above-described pattern (FIG. 16B), and after removing the insulating film 31, the insulating films 32 are formed again on both surfaces of the SOI substrate 1. (FIG. 16
(C)) Then, a predetermined position of the insulating film 32 is removed (FIG. 16D). Then, after the lower metal electrode 8 is formed (FIG. 16E), the piezoelectric films 21 to 24 are formed (FIG. 16F).

Next, the bonding pad 4 and the substrate electrode 5
(5a, 5b), wiring 6, upper electrode 7, and mirror 10
Are formed by a metal thin film (FIG. 17A). Then, an insulating film 33 is formed on the entire surface (FIG. 17B),
A predetermined portion of the insulating film 32 on the back surface is removed, and the substrate portion 1c is etched, and further, the insulating film 1a is etched to form a thin portion 2 (FIG. 17C).

After removing the insulating film 32 on the back surface,
The Pyrex glass 11 is bonded (FIG. 17D).
After that, the through groove 3 is formed in the thin portion 2. In this case, the first and second spring portions 14a, 14b, 13a, 13b
So that it has a bent structure. Thus, an optical scanning device having the structure shown in FIG. 10 is obtained (FIG. 17).
(E)).

According to this manufacturing method, by using the SOI substrate, the rectangle formed by etching from the back surface can be made parallel to the outer periphery of the silicon chip as shown in FIG. 24 can be made perpendicular to its longitudinal direction to have an ideal shape. Note that, in the above-described manufacturing method, a method using an SOI substrate is described; however, manufacturing can be performed without using an SOI substrate. For example, the plane orientation of the silicon substrate is set to (10
0), the conductivity type is p-type, and the low-resistance layer 9 (9a, 9b)
Is n-type, the piezoresistance coefficient of n-type silicon is <100>, so that the spring portions 13a, 13
If the longitudinal direction of b, 14a, 14b is set in the <100> direction, the maximum resistance change can be obtained. Therefore, if such a silicon substrate is used, an optical scanning device can be manufactured using the same method as in the first embodiment. Also,
Using a p-type epi-substrate (p-type layer has a thickness equivalent to the thickness of the thin portion 2) with a plane orientation of the silicon substrate of (100) and a conductivity type of n-type, A low resistance layer 9 (9a, 9b) may be provided by providing a layer. In these manufacturing methods, the spring portions 13a, 13b, 14
If the entirety of a and 14b in the thickness direction is n-type, the resistance value hardly changes. Therefore, it is preferable that the thickness be at most about half of the thickness direction. Also, when such a manufacturing method is used, the rectangle formed by etching from the back surface can be made parallel to the outer periphery of the silicon chip as shown in FIG.

The fourth embodiment can also be implemented as in the second and third embodiments. The present invention is not limited to the various embodiments described above, and can be appropriately modified within the scope described in the claims. For example, first and second spring portions 1
4 and 13, a torsion beam portion, a ring portion including first and second frame portions 16 and 15, and a mirror portion 1
The thickness of the thin portion 2 in the case 2 may not be constant, but only the torsion beam portion and the ring portion which require rigidity may be thickened. In this case, since the mass of the movable portion increases, a desired resonance frequency can be obtained with smaller dimensions.

The insulating films 32 and 33 formed on the torsion beam portion, the ring portion and the mirror portion 12 are desirably free from stress with respect to silicon. This is because if the stress remains, the mirror portion 12 may be warped, causing a problem that the reflected light diverges. In addition to the formation of the metal thin film 10 in the mirror section 12, it is also possible to adopt a configuration in which a mirror is attached. Further, the light emitting portion is not limited to the one that performs light reflection, and a light emitting device, for example, a semiconductor laser device may be configured as the light emitting portion.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an optical scanning device according to a first embodiment.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a process chart showing a manufacturing process of the optical scanning device shown in FIG. 1;

FIG. 4 is a process chart showing a manufacturing process following the process shown in FIG. 3;

FIG. 5 is a schematic configuration diagram of an optical scanning device according to a second embodiment of the present invention.

FIG. 6 is a sectional view of the optical scanning device shown in FIG.

FIG. 7 is a schematic configuration diagram showing a modification of the second embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of an optical scanning device according to a third embodiment of the present invention.

FIG. 9 is a cross-sectional view of the optical scanning device shown in FIG.

FIG. 10 is a schematic configuration diagram of an optical scanning device according to a fourth embodiment of the present invention.

11 is a diagram illustrating a circuit configuration of a monitor unit in the optical scanning device illustrated in FIG.

FIG. 12 is a diagram showing a configuration of a drive circuit in the optical scanning device shown in FIG.

FIG. 13 is a schematic configuration diagram showing a modification of the fourth embodiment of the present invention.

FIG. 14 is a schematic configuration diagram showing another modification of the fourth embodiment of the present invention.

FIG. 15 is a diagram for explaining a problem when the optical scanning device shown in FIG. 10 is manufactured.

FIG. 16 is a process chart showing a manufacturing process of the optical scanning device shown in FIG. 10;

FIG. 17 is a process chart showing a manufacturing process following the process shown in FIG. 16;

FIG. 18 is a diagram showing a state after back surface etching in the manufacturing method shown in FIGS. 16 and 17;

FIG. 19 is a configuration diagram showing a conventional optical scanning device.

20 is a diagram for explaining the operation of the optical scanning device shown in FIG.

21 is a diagram illustrating a configuration in a case where the optical scanning device illustrated in FIG. 19 is applied to an optical information reading device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Thin part, 3 ... Through-groove, 10 ... Mirror, 12 ... Mirror part, 13 ... Second spring part (second
Torsional vibrating part), 14 ... first spring part (first torsional vibrating part), 15 ... second frame part (second holding part), 16 ... first frame part (first holding part), 21 ~
24: Piezoelectric film, 11, 41: Pyrex glass, 5
0 ... Through hole.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayoshi Esashi 1-11-11, Yagiyama-Minami, Taihaku-ku, Sendai-shi, Miyagi 9 (72) Inventor Yoshinori Otsuka 1-1-1, Showa-cho, Kariya-shi, Aichi Pref. 72) Inventor Tadashi Hattori 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Inside DENSO Corporation

Claims (10)

[Claims] 1. A semiconductor substrate (1) having a thin portion (2) formed thereon, and vibrating means (21 to 2) for vibrating the thin portion.
4), wherein the thin portion is provided with a light emitting portion (10) for emitting light. 2. The optical scanning device according to claim 1, wherein the light emitting unit is a metal thin film forming a mirror. 3. The thin portion has a mirror portion (12) on which the metal thin film is formed, and the mirror portion vibrates about two different axes as rotation axes by vibrating by the vibrating means. The optical scanning device according to claim 2, wherein: 4. A monitoring means (63a, 63b,
The optical scanning device according to claim 3, wherein the optical scanning device includes: 64 a, 64 b, 65 to 68). 5. The thin portion has torsional vibrating portions (13a, 13b, 14a, 14b) that are twisted by the vibration of the vibrating means to forcibly vibrate the mirror portion,
The optical scanning device according to claim 4, wherein the monitoring unit performs the monitoring based on a torsion state of the torsional vibration unit. 6. The torsional vibrating portion includes a variable resistor (63) whose resistance value changes due to stress generated by the torsion.
6. The optical scanning device according to claim 5, comprising: (a), (64a), (64b), and (63b), wherein the monitoring means performs the monitoring based on a resistance value of the variable resistor. 7. The thin portion includes a mirror portion (12) on which the metal thin film is formed, and a first portion formed through a predetermined gap with respect to the mirror portion.
And the mirror portion and the first holding portion are connected and twisted when a periodic external force is applied, and the direction of the twist is determined by the magnitude corresponding to the rotation angle of the twist. Are formed with a first torsional vibrator (14, 14a, 14b) for forcibly vibrating the mirror section so as to generate a rotational torque in the opposite direction, and a predetermined gap with the first holding section. A second holding part (15), which connects the first holding part and the second holding part, is twisted when a periodic external force is applied, and has a magnitude corresponding to a rotation angle of the twist. A second torsional vibrator (13, 1) forcibly vibrating the mirror unit via the first holding unit so as to generate a rotational torque in a direction opposite to the direction of the torsion.
3a, 13b), wherein the vibration means applies the periodic external force to each of the first and second torsional vibrating portions. The optical scanning device according to claim 1. 8. The mirror portion according to claim 3, wherein a through hole is formed in the mirror portion, and light is reflected from the metal thin film through the through hole. The optical scanning device according to one of the above. 9. The optical scanning device according to claim 1, wherein the vibrating means is a piezoelectric element (21 to 24) formed on a support portion of the thin portion. apparatus. 10. The device according to claim 1, wherein the thin portion is air-tightly covered with a member having at least a light emitting direction that is transparent. Optical scanning device.