JP2001013428A - Light modulation device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an SN ratio by increasing a change in curvature of a reflecting interface and improving a light-condensing performance also to realize miniaturization and space saving. SOLUTION: This light modulation device has a piezo-electric element 30 consisting of a piezo-electric material layer 33 and a 1st- and a 2nd electrodes 32, 34 interposing it in-between, also a mirror element 20 having a mirror film structure 35 reflecting light, and a driving element 30 arranged corresponding to the mirror element 20. In this case, the piezo-electric element 30 is fixed on a substrate 11 via a supporting member 31a arranged on one of the faces, and connection wiring 36, 37 to be connected with the 1st- and the 2nd electrodes 32, 34 are arranged extending up to drive wiring 53, 54 provided on the substrate 11 via the supporting member 31a, and this arrangement makes it easier to connect the drive wiring 53, 54 with the connection wiring 36, 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art Conventionally, as a light modulation device for modulating light to perform display, for example, a voltage is applied to an electrode provided on a substrate, and a mirror is tilted by electrostatic force or the like to modulate incident light. In addition, there is known a device that modulates incident light by providing a mirror on a piezoelectric element in which a piezoelectric layer is sandwiched between a pair of electrode films and inclining the mirror by deforming the piezoelectric element.

[0002] Further, as a device utilizing a piezoelectric element,
As can be seen in Japanese Patent Application Laid-Open No. 9-504387, a mirror film made of a thin film or the like is formed on the surface of a cantilever-shaped piezoelectric element, and this mirror film is bent by deforming the piezoelectric element to make incident light. It is also proposed to change the direction.

[0003]

However, the light modulation device using such a piezoelectric element has a cantilever structure supporting one end in the longitudinal direction of the piezoelectric element in any case. In the case of (1), there is a problem that the modulation performance is low because the piezoelectric element is deformed in only one direction along the longitudinal direction to change the direction of light to perform modulation.

The present invention has been made in view of the above circumstances, and an optical modulation device and a small-sized and space-saving optical modulator capable of increasing a change in curvature of a reflecting surface to improve light-collecting performance, improving an SN ratio, and reducing the space. It is an object to provide a display device using the same.

[0005]

According to a first aspect of the present invention, there is provided a piezoelectric element including a piezoelectric layer and first and second electrodes sandwiching the piezoelectric layer, and reflects light. In a light modulation device having a mirror element having a mirror film structure and a driving element provided corresponding to the mirror element, the piezoelectric element is fixed on a substrate via a support member provided on one surface side. Wherein the connection wiring connected to the first and second electrodes extends to the drive wiring provided on the substrate via the support member. In the device.

In the first aspect, since the connection wiring is extended via the support member, the wiring can be formed relatively easily irrespective of the shape of the mirror element.
A space-saving light modulation device can be realized.

According to a second aspect of the present invention, in the first aspect, the piezoelectric element extends two-dimensionally from a connection portion with the support member, and a substantially central portion thereof is connected to the support member. The light modulation device is characterized by being deformed into a curved shape with the connection portion as a fulcrum by driving.

[0008] In the second aspect, the piezoelectric element constituting the mirror element is deformed with the connecting portion with the support member provided at the center thereof as a fulcrum, and the deformed end is a free end. The change in curvature can be increased to improve the light-collecting performance.

According to a third aspect of the present invention, in the first aspect, the piezoelectric element is extended substantially in one direction from a connection portion with the support member, and is separated by the support member at one longitudinal end thereof. The light modulation device is supported in a beam state, and its tip deforms in the thickness direction around the connection portion by driving.

[0010] In the third aspect, the piezoelectric element is supported in a cantilever state, and deforms with the end portion as a fulcrum.

[0011] A fourth aspect of the present invention is the light modulation device according to any one of the first to third aspects, wherein the piezoelectric element has an elastic plate on the one surface side.

In the fourth aspect, since the support member is joined to the elastic plate provided on one side of the piezoelectric element,
The piezoelectric element is deformed with the joint as a fulcrum.

A fifth aspect of the present invention is the light modulation device according to any one of the first to fourth aspects, wherein the piezoelectric element has the mirror film structure on the other surface side.

In the fifth aspect, since the supporting member is joined to one side of the piezoelectric element, the piezoelectric element is deformed with this joint as a fulcrum, and the mirror film structure on the other surface is deformed.

According to a sixth aspect of the present invention, in the fifth aspect, the mirror film structure of the piezoelectric element is constituted by the second electrode on the other surface side or a reflection film provided thereon. A light modulation device.

In the sixth aspect, the second electrode or the reflection film of the piezoelectric element reflects light.

According to a seventh aspect of the present invention, in the fourth aspect, a mirror member constituting the mirror film structure is provided at a longitudinal end of the piezoelectric element opposite to the support member. And a tilt angle of a reflection surface of the mirror member is changed by driving the piezoelectric element.

In the seventh aspect, the mirror member provided on the piezoelectric element reflects light, and modulates the light by changing the tilt angle of the mirror member.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, a piezoelectric element removing portion is formed by removing at least a part of a region of the piezoelectric element facing the support member, A connection line for connecting at least the electrode on the other surface side of the piezoelectric element and the corresponding drive line is provided in the piezoelectric element removing section, in the light modulation device.

In the eighth aspect, the connection wiring and the drive wiring connected to at least one electrode of the piezoelectric element are connected via the piezoelectric element removing section.

A ninth aspect of the present invention is the optical modulation device according to the eighth aspect, wherein the piezoelectric element removing portion is a through hole penetrating the piezoelectric element in a thickness direction.

In the ninth aspect, the drive wiring and the connection wiring are connected in the through hole.

According to a tenth aspect of the present invention, in the eighth or ninth aspect, the support member is an annular member having a support member penetrating portion provided on the substrate, and the piezoelectric element removing portion is provided on the support member. The light modulation device is in communication with the member penetrating portion.

In the tenth aspect, the drive wiring is exposed in the support member penetrating portion, and connection with the connection wiring is relatively easy.

According to an eleventh aspect of the present invention, in the tenth aspect, at least the connection wiring for connecting the electrode on the other surface side of the piezoelectric element and the corresponding driving wiring is provided in the support member penetrating portion. The light modulation device is provided.

In the eleventh aspect, the drive wiring and the connection wiring are connected on the substrate in the through portion.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the support member is formed by projecting a layer constituting the one surface side of the piezoelectric element toward the substrate. A light modulation device.

In the twelfth aspect, the piezoelectric element and the support member are securely fixed, and the manufacturing process is simplified.

According to a thirteenth aspect of the present invention, in the twelfth aspect, the layer constituting the supporting member is an electrode on the one surface of the piezoelectric element, and the electrode is electrically connected to the connection wiring. The light modulation device is characterized by being connected.

In the thirteenth aspect, the electrode on one side of the piezoelectric element and the corresponding drive wiring are electrically connected by the support member itself, and the structure is simplified.

According to a fourteenth aspect of the present invention, in any one of the eighth to twelfth aspects, the connection wiring for connecting each of the first electrode and the second electrode to the driving wiring is provided. The light modulation device is characterized in that each of the light modulation devices is arranged in the support member penetration portion so as to be separated in a plane.

In the fourteenth aspect, the wiring for connecting both the first electrode and the second electrode can be formed in the same process, and the manufacturing process is simplified.

According to a fifteenth aspect of the present invention, in any one of the eighth to twelfth aspects, the connection wiring for connecting each of the first electrode and the second electrode to the driving wiring is provided. And a light modulation device, wherein the light modulation device is laminated and formed in the support member penetrating portion via an insulating layer.

In the fifteenth aspect, the first electrode and the second electrode are insulated by the insulating layer.

The sixteenth aspect of the present invention is directed to the fourteenth or fifteenth aspect.
In the light modulating device, the electrode on the one surface side of the piezoelectric element has a surface exposed near an end on the piezoelectric element removing portion side.

In the sixteenth aspect, the electrode on the substrate side of the piezoelectric element and the connection wiring are securely connected at the portion where the surface is exposed.

According to a seventeenth aspect of the present invention, in any one of the first to ninth aspects, the connection wiring extends outside the support member via a connection portion between the support member and the piezoelectric element. The light modulation device is characterized in that:

In the seventeenth aspect, the connection wiring can be formed relatively easily.

According to an eighteenth aspect of the present invention, in any one of the first to ninth aspects, the driving wiring is extended to an upper surface of an island member provided as an island constituting the support member. The drive line is exposed in the piezoelectric element removing portion, and the connection line is connected to the exposed drive line.

In the eighteenth aspect, the drive wiring and the connection wiring can be relatively easily connected in the piezoelectric element removing section.

A nineteenth aspect of the present invention is the light modulation device according to the eighteenth aspect, wherein the height of the upper surface of the island member and the height of the lower surface of the piezoelectric element are substantially the same.

In the nineteenth aspect, the piezoelectric element is easily deformed, and the curvature of the reflection surface becomes large.

According to a twentieth aspect of the present invention, in any one of the first to nineteenth aspects, the substrate is a silicon single crystal substrate, and the driving element is constituted by a semiconductor integrated circuit provided on the substrate. A light modulation device.

In the twentieth aspect, the piezoelectric element is driven by a semiconductor integrated circuit provided on a silicon substrate.

A twenty-first aspect of the present invention is the light modulation device according to any one of the first to twentieth aspects, wherein the mirror elements are arranged in a two-dimensional array.

In the twenty-first aspect, an image can be projected on a screen or the like via mirror elements arranged in a two-dimensional array.

According to a twenty-second aspect of the present invention, there is provided the light modulation device according to any one of the first to twenty-first aspects, a light source, light from the light source being incident on the light modulation device, and An optical system that emits only one of reflected light when the piezoelectric element is driven or not driven.

In the twenty-second aspect, by using a light modulation device having a large change in the curvature of the mirror film structure to improve the light condensing performance, it is possible to improve the SN ratio and to reduce the size and space. A display device can be realized.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments.

(Embodiment 1) FIG. 1 is a perspective view schematically showing an optical modulation device according to Embodiment 1, and FIG. 2 is a cross-sectional view showing one mirror element.

As shown in FIG. 1, a light modulation device 10 according to the present embodiment includes a mirror substrate 11 formed of, for example, a silicon (Si) substrate having a thickness of 500 μm, and It has a mirror element 20 provided in a dimensional array and a drive element 50 for deforming the mirror element 20.

The mirror element 20 is, for example, 1280 × 1
For example, as shown in FIG. 2, each mirror element 20 includes a lower electrode film 32, a piezoelectric layer 33, and an upper electrode film 34 formed on an elastic plate 31.
And a reflection film 35 provided over substantially the entire surface of the upper electrode film 34 of the piezoelectric element 30. The surface of each mirror element 20 has, for example, a substantially square shape with a side of about 20 μm, and a through hole to be described later is formed at the center. In the present embodiment, a substantially cylindrical support portion 31a formed by projecting the elastic plate 31 toward the mirror substrate 11 is provided at a substantially central portion of the elastic plate 31,
The mirror element 20 is fixed to the mirror substrate 11 via the support 31a. In other words, these mirror elements 20 have a side of about 20 μ
The area of m is deformed. The outer diameter of the support portion 31a that holds the mirror element 20 is not particularly limited, but is preferably small enough to hold the mirror element 20 reliably.

The support portion 31a and the mirror element 20 in a region opposed to the support portion 31a are formed with a through hole 40 penetrating them to expose the mirror substrate 11. The element 50 and the upper electrode film 34 and the lower electrode film 32 of the piezoelectric element 30 are connected to each other.

The driving element 50 is a transistor for driving the piezoelectric element 30, and is, for example, an n-channel MOS transistor provided on the p-type silicon substrate in correspondence with each mirror element 20. These drive elements 50 are
Each mirror element 20 is covered with the first interlayer insulating film 12, and is actually provided on the first interlayer insulating film 12 via a support 31 a.

Here, the basic configuration of the MOS transistor which is the driving element 50 for driving the piezoelectric element 30 will be described. As shown in FIG. 3, the MOS transistor has a source 51 and a drain 52 each doped with a donor at two positions on a mirror substrate 11 which is a p-type silicon substrate. The source 51 is connected to the lower electrode film 32 of the piezoelectric element 30 via a drive wiring 53 and the like, and the upper electrode film 34 is
The signal line 54 is connected. Also, the drain 52
Is connected to a second signal line 55, and a gate electrode 56 is provided between the source 51 and the drain 52 via a gate insulating film 59.

In the MOS transistor having such a configuration, when a positive bias voltage is applied to the gate electrode 56 with respect to the source 51, holes are generated on the semiconductor surface in contact with the gate insulating film 59 by the positive voltage applied to the surface. Are expelled from the surface, electrons are induced by electrostatic induction in the mirror substrate 11 which is a p-type silicon substrate, and a channel 57 which is a passage of electrons is formed. At this time, when a positive voltage is applied to the drain 52 with respect to the source 51, the electrons injected from the source 51 move to the drain 52 through the channel 57. That is, the drain 5
An electric current flows between 2 and the source 51 to drive the piezoelectric element 30.

Here, the wiring structure between the piezoelectric element 30 and the driving element 50 according to the present embodiment will be described. FIG.
FIG. 3 is a plan view schematically showing one of the driving elements 50. FIG. 2 is a diagram showing a cross section taken along line AA of FIG.

As shown in FIGS. 2 and 4, the support 31a
In the first interlayer insulating film 12 in a region corresponding to the through hole 40, a connection terminal portion 58 for connecting the lower electrode film 32 and the source 51 of the driving element 50 is provided. In this embodiment, the connection terminal portion 58 is formed with a contact hole 12a exposing the source 51 in the first interlayer insulating film 12 and a drive wiring 53 connected to the source 51 in the contact hole 12a. It is configured to extend over one interlayer insulating film 12. The drive wiring 53 serving as the connection terminal portion 58 and the lower electrode film 32 are partially extended in the circumferential direction on the second interlayer insulating film 13 provided in the through hole 40. Connection wiring 36. The connection terminal portion 58 is not limited to the configuration in which the drive wiring 53 is formed in the contact hole 12a, but can be connected to the lower electrode film 32 via the contact hole 12a formed in the first interlayer insulating film 12. For example, a plug member such as tungsten (W) is buried in the contact hole 12a,
2 may be connected.

On both sides of the connection terminal portion 58, a first signal line 54 for supplying a signal to the upper electrode film 34 and a second signal line 55 for connecting to the drain 52 of the driving element 50 are provided.
However, in the present embodiment, they extend in a direction substantially orthogonal to the gate electrode 56.

The first signal line 54 is provided such that at least one end in the width direction is located in a region facing the through hole 40 of the support portion 31a. This first signal line 54
The upper electrode film 34 is connected to the upper electrode film 34 by an upper electrode connection wiring 37 extending over the second interlayer insulating film 13 provided in the through hole 40. For example, in the present embodiment, the reflection film 35 also serves as the connection wiring 37 for the upper electrode,
Extends from the upper electrode film 34 to a part of the through hole 40 in the circumferential direction, and is connected to the exposed portion 54 a at one end in the width direction of the first signal line 54. It goes without saying that the reflection film 35 and the connection wiring 37 for the upper electrode may be separately provided.

In this embodiment, the lower electrode connection wiring 36 and the reflection film 35 serving also as the upper electrode connection wiring 37 are provided on the second interlayer insulating film 13 on the same plane in this embodiment. But is insulated reliably. In other words, these connection wirings 36 and 37 are provided at predetermined positions in the through holes 40 and opposed to each other in a predetermined width and are separated in a plane. Is surely insulated by the interlayer insulating film 13.

In the present embodiment, the second signal line 55 is provided outside the support portion 31a, and is provided on the first interlayer insulating film 12 in a region facing the drain 52 of the driving element 50. It is connected to the drain 52 via the contact hole 12b.

In such a configuration, by operating the driving element 50 as described above, a desired voltage can be selectively applied to the desired piezoelectric element 30 to drive it, and the deformation control of the mirror element 20 is easily performed. be able to.

The light modulation device 1 of the present embodiment as described above
The manufacturing method of No. 0 is not particularly limited, but in the present embodiment, it was manufactured by the following steps. 5 and 6 are cross-sectional views illustrating a method for manufacturing the light modulation device of the present embodiment.

First, as shown in FIG. 5A, a driving element 5 which is a MOS transistor is previously formed on a p-type silicon substrate.
0 on the mirror substrate 11 on which the first interlayer insulating film 12 is formed.
Is formed, and thereafter, patterning is performed to form a contact hole 12a exposing the source 51 in a region facing the source 51 of the driving element 50. The material of the first interlayer insulating film 12 is not particularly limited as long as it is an insulating material. For example, silicon nitride, silicon oxide, or the like can be used.

Next, as shown in FIG. 5B, a drive wiring 53 and a first signal line 54 are formed on the first interlayer insulating film 12.
And the second signal line 55 is formed. That is, the wiring film 60 is formed on the entire surface of the first interlayer insulating film 12 and then patterned to form the driving wiring 53, the first signal line 54, and the second signal line 55.

Next, as shown in FIG. 5C, the sacrificial layer 7 is formed.
0 and patterning each mirror element 20
The sacrificial layer removing portion 71 is formed correspondingly. This sacrificial layer 7
0 is for forming the support portion 31a corresponding to each mirror element 20, and the material thereof is not particularly limited. For example, it is preferable to use polysilicon or phosphorus-doped silicon oxide (PSG), In the present embodiment, PSG having a relatively high etching rate is used.

Next, as shown in FIG.
The elastic plate 3 constituting the piezoelectric element 30 follows the shape of
1. Lower electrode film 32, piezoelectric layer 33 and upper electrode film 34 are sequentially laminated.

The material of the elastic plate 31 is not particularly limited as long as it is elastically deformable and has a predetermined rigidity. In the present embodiment, after forming the zirconium layer, the diffusion plate is heated at 500 to 1200 ° C., for example. To form an elastic plate 31 made of zirconium oxide.

The material of the lower electrode film 32 is preferably platinum or the like. This is because, as described later, the piezoelectric layer 33 formed by a sputtering method or a sol-gel method needs to be crystallized by firing at a temperature of about 600 to 1000 ° C. in an air atmosphere or an oxygen atmosphere after the film formation. Because there is. That is, the material of the lower electrode film 32 must be able to maintain conductivity at such a high temperature and in an oxidizing atmosphere. In particular, when the piezoelectric layer 33 is made of lead zirconate titanate (PZT), It is desirable that the change in conductivity due to the diffusion of lead oxide (PbO) is small. For these reasons, in the present embodiment, platinum is formed by sputtering.

The material of the piezoelectric layer 33 is preferably a lead zirconate titanate (PZT) -based material. In the present embodiment, a so-called sol in which a metal organic substance is dissolved and dispersed in a catalyst is applied, dried and gelled. Further, the piezoelectric layer 33 was formed by using a so-called sol-gel method by firing at a high temperature to obtain a metal oxide. The method for forming the piezoelectric layer 33 is not particularly limited, and may be formed by, for example, a sputtering method.

Further, after forming a precursor film of lead zirconate titanate by a sol-gel method, a sputtering method or the like,
A method of growing crystals at a low temperature by a high-pressure treatment method in an alkaline aqueous solution may be used.

The upper electrode film 34 may be made of a material having high conductivity, and may be made of a number of metals such as aluminum, gold, nickel, and platinum, or a conductive oxide. In the present embodiment, platinum is formed by sputtering.

Next, as shown in FIG. 6A, the upper electrode film 34 and the piezoelectric layer 33 constituting the piezoelectric element 30 are patterned by etching. Subsequently, as shown in FIG. 6B, the lower electrode film 32 and the elastic plate 31 are patterned by etching to form the respective piezoelectric elements 30 constituting the mirror element 20, and at the substantially center of the respective piezoelectric elements 30. A through hole 40 exposing the drive wiring 53 and the first signal line 54 is formed in the portion. At this time, it is preferable that the end of the lower electrode film 32 on the side of the through hole 40 is patterned so as to be located at least inside the piezoelectric layer 33 so that the surface of the lower electrode film 32 is exposed.

Next, as shown in FIG. 6C, a second interlayer insulating film 13 is formed to cover the piezoelectric element 30 and the through hole 40, and is patterned. More specifically, the upper electrode exposed portion 34 in which the upper electrode film 34 is exposed over substantially the entire circumferential direction except for both end portions on the upper electrode film 37 by patterning.
a, and a lower electrode exposed portion 32a is formed on the lower electrode film 32 such that a part of the surface in the circumferential direction is exposed. Further, a drive wiring exposed portion 53a at least a part of which is exposed is formed on the drive wiring 53 on the mirror substrate 11, and a signal line exposed portion 54a at which a part of the first signal line 54 is exposed is formed.

By patterning the second interlayer insulating film 13 in this manner, the second interlayer insulating film 13 allows the lower electrode connection wiring 36 and the upper electrode connection wiring 37 to be formed in the following steps. , And the drive wiring 53 and the first signal line 54 are insulated. The material of the second interlayer insulating film 13 may be, for example, polyimide, in addition to silicon nitride and silicon oxide, like the first interlayer insulating film 12.

Next, as shown in FIG. 6D, a reflection film 35 is formed on the upper electrode film 34, and the lower electrode connection wiring 36 and the upper electrode connection wiring are formed on the inner peripheral surface of the through hole 40. 37 is formed. In the present embodiment, the reflection film 35 also serves as the upper electrode connection wiring 37, and the reflection film 35 and the lower electrode connection wiring 36 are formed in the same plane, that is, in the same layer. Accordingly, the connection wiring film 61 serving as the reflection film 35 and the connection wiring 36 for the lower electrode can be formed over the upper electrode film 34 over the inner surface of the through-hole 40 and by patterning and separation. That is, the reflection film 35 is formed over substantially the entire upper surface of the upper electrode film 34, and the reflection film 35 is formed on a part of the through hole 40 in the circumferential direction.
The connection wiring 37 for the upper electrode is extended continuously from a part of the above to the signal line exposed portion 54a. Further, a lower electrode connection wiring 36 for connecting the lower electrode film exposed part 32a and the drive wiring exposed part 53a is formed in a part of the through hole 40 in the circumferential direction.

In this embodiment, since the reflection film 35 also serves as the upper electrode connection wiring 37 in this embodiment, the connection wiring film 61 is a conductive material and has a light reflectance. It is preferably high, for example, aluminum (Al) or silver (Ag) is preferably used.

Thereafter, the sacrificial layer 70 is removed by etching. In the present embodiment, the material of the sacrificial layer 70 is P
Since SG was used, etching was performed using a hydrofluoric acid aqueous solution. When polysilicon is used, etching can be performed with a mixed aqueous solution of hydrofluoric acid and nitric acid or an aqueous solution of potassium hydroxide.

The above is a series of manufacturing steps of the light modulation device of the present embodiment. Although the connection between the second signal line 55 and the drain 52 of the drive element 50 is not described, similar to the connection between the drive wiring 53 and the source 51, the first interlayer in the region facing the drain 52 Insulating film 1
2 to form the second signal line 55
And the drain 52 may be connected.

Here, the operation of the thus formed light modulation device of the present embodiment will be described. FIG.
FIG. 1 is a diagram schematically illustrating a light modulation device of the present embodiment and an optical path of light applied to the light modulation device.

The light modulation device 10 modulates light by deforming the mirror element 20. In this embodiment, the mirror element 20 is substantially flat when no voltage is applied to the piezoelectric element 30. When a voltage is applied to the piezoelectric element 30 by the switching of the driving element 50, the piezoelectric layer 33 of the piezoelectric element 30 contracts in the in-plane direction, and the mirror element 20 moves the support portion 31a to which the elastic plate 31 is joined. As a fulcrum, the piezoelectric element 30 is deformed with the elastic plate 31 side being convex, so that the reflection film 35 becomes a concave mirror.

The light modulation device 10 according to the present embodiment is, for example, as shown in FIG.
A light-shielding dot array 100 is provided at a position facing 0. The light-shielding dot array 100 is made of, for example, a transparent substrate such as glass, and is provided with light-shielding dots 101 facing each mirror element. This light-shielding dot 101
Is composed of a light absorbing material, and examples thereof include carbon black, black pigment, and black dye dispersed in a resin.
Further, the light-shielding dot array 100 includes each light-shielding dot 101.
Are provided near the focal point of the mirror element 20B deformed into a concave mirror shape. For example, in the configuration of the present embodiment, since the amount of deformation of the mirror element 20B is 0.2 μm, the light-shielding dots 101 are provided at a distance of about 0.2 mm from each mirror element 20.

In such a configuration, when no voltage is applied to the piezoelectric element 30, the incident light 90 is incident on the reflection film 35 of the mirror element 20A substantially at a right angle.
The incident light 90 is emitted in substantially the same optical path as the incident optical path. On the other hand, when a voltage is applied to the piezoelectric element 30 by the driving element 50, the mirror element is deformed to become a concave mirror, and after being reflected, the light is collected in the focal direction of the deformed mirror element 20B. In the present embodiment, since the light-shielding dot 101 is provided near the focal point of the deformed mirror element 20B as described above, the incident light 90 is reflected by the light-shielding dot 101 and then condensed on the light-shielding dot 101 to return in the incident direction. There is no.
That is, when such a light modulation device 10 is used for a display device or the like, ON / OFF control of the incident light 90 can be easily performed by applying or not applying a voltage to the piezoelectric element 30. In the example described above, the piezoelectric element 30
Is turned on when it is not deformed, and turned off when it is deformed. Of course, it can be set to be the reverse of this.

In the configuration of the present embodiment as described above, the upper electrode film 34 and the lower electrode film 32 of the piezoelectric element 30 and the driving element 5
The connection wiring 37 for the upper electrode and the connection wiring 36 for the lower electrode connecting to 0 can be formed relatively easily. Also,
The upper electrode connection wiring 37 and the lower electrode connection wiring 36
Is formed in the through hole 40 formed in the support portion 31a. Thus, a light modulation device having a structure in which the piezoelectric element 30 extends two-dimensionally from the support portion 31a can be realized, and its wiring can be formed relatively easily.

Therefore, it is possible to realize an optical modulation device in which the amount of deformation of the mirror element is sufficiently large as compared with the structure in which the periphery of the mirror element is deformed while being held. In such a light modulation device, the aperture ratio of the reflection surface is large, and the reflection efficiency is improved. Furthermore, the light collection rate is high and S
An optical modulation device having a large N ratio can be realized.
In addition, since the wiring connecting at least the upper electrode film of the piezoelectric element and the driving element is provided in a portion of the mirror element that is not substantially deformed, the deformation is not restricted by the wiring, and the performance is reduced. Can be prevented.

In this embodiment, the elastic plate 31 which is the layer closest to the mirror substrate 11 of the piezoelectric element 30 is protruded toward the mirror substrate 11 to form the support portion 31a. Although the electrode film 32 is formed, the invention is not limited to this. For example, the lower electrode film 32 may also serve as an elastic plate. In such a configuration, since the support portion is formed of the lower electrode film, the lower electrode film and the drive wire are electrically connected by connecting the support portion to the drive wire.

Further, in the present embodiment, the lower electrode connection wiring 36 and the upper electrode connection wiring 37 are provided separately at opposing positions in the through hole 40 in plan view, but the invention is not limited to this. Instead, for example, they may be arranged at substantially the same position in the through hole 40 and may be formed by lamination with an insulating layer interposed therebetween.

In the above-described embodiment, the first signal line 54 is grounded at the end in the extending direction. However, the present invention is not limited to this.

(Embodiment 2) FIG. 8 is a sectional view of an optical modulation device according to Embodiment 2.

The present embodiment is an example in which the support member for supporting the mirror element 20 is formed of a member different from the mirror element 20. For example, in this embodiment, as shown in FIG. The mirror element 20 is fixed on the mirror substrate 11 via the support member 80, and a through portion 40 </ b> A where the surface of the support member 80 is exposed is provided in a region facing the support member 80. Is provided.

In this embodiment, the contact hole 12a exposing the source 51 of the drive element 50 is formed in the first interlayer insulating film 12 outside the support member 80.
The drive wiring 53 extends from the contact hole 12a to the region above the support member 80 facing the through portion 40A, and is connected to the lower electrode film 32 via the lower electrode connection wire 36 in the through portion 40A. ing. The first signal line 54 also extends to a position above the support member 80, and the upper electrode film 34 is formed on the support member 80 in a region facing the through portion 40 </ b> A via the reflection film 35 serving also as the upper electrode connection wiring 37. Is connected to

The method of manufacturing the light modulation device having such a configuration is not particularly limited. For example, in this embodiment, the light modulation device was manufactured by the following steps. FIG. 9 is a cross-sectional view illustrating a manufacturing process of the light modulation device according to the second embodiment.

First, as shown in FIG. 9A, as in the first embodiment, a first interlayer insulating film is formed on a mirror substrate 11 on which a driving element 50 composed of a MOS transistor is formed in advance on a p-type silicon substrate. Then, a support member material layer 81 is formed on the first interlayer insulating film 12 and patterned to form an island-shaped support member 80 corresponding to each mirror element 20.

Next, as shown in FIG. 9B, the first interlayer insulating film 12 is patterned near each support member 80 of the first interlayer insulating film 12 so that the source 51 of the drive element 50 is formed. Is formed to expose the contact hole 12a.

Next, as shown in FIG. 9C, a drive wiring 53, a first signal line 54, and a second signal line 55 are formed on the first interlayer insulating film 12 and the support member 80.
That is, the wiring film 60 is formed on the entire surface of the first interlayer insulating film 12 and the support member 80 and then patterned to form the drive wiring 53, the first signal line 54, and the second signal line 55.

Next, as shown in FIG. 9D, a sacrifice layer 70 is formed around the support member 80. The layers constituting the piezoelectric element 30 are formed on the sacrificial layer 70 in the following steps.
It is preferable that the height of the upper surface is substantially the same. Therefore, it is preferable that the sacrificial layer 70 be formed at substantially the same height as the support member 80.

After that, similar to the manufacturing process of the first embodiment shown in FIG. 6, the sacrifice layer 70 is removed after the formation and patterning of the piezoelectric element 30 and the reflection film 35 and the like. Light modulation devices can be manufactured.

In the configuration of this embodiment,
As in the first embodiment, the wiring connecting the upper electrode film 34 and the lower electrode film 32 of the piezoelectric element 30 to the driving element 50 can be formed relatively easily, and the amount of deformation of the mirror element is sufficiently increased. An optical modulation device can be realized.

In the present embodiment, the connection between the drive wiring 53 and the lower electrode connection wiring 36 is performed on the support member 80. However, the present invention is not limited to this. A communication hole communicating with the mirror substrate 11 may be provided, and the communication hole may be formed on the mirror substrate 11.

(Other Embodiments) Although the embodiments of the present invention have been described above, the light modulation device of the present invention is not limited to the above-described embodiments, but anyway, it is relatively easy. The connection wiring between the piezoelectric element and the driving element can be formed.

In the above-described embodiment, the reflection film 35
Acts as a concave mirror, but the invention is not limited to this. The film forming conditions and the like may be appropriately adjusted to act as a convex mirror.

In the above-described embodiment, for example, the piezoelectric element 30 is two-dimensionally extended from a portion supporting the mirror element 20, for example, from a portion corresponding to the support member 80, and a portion corresponding to the support member 80. With mirror element 2
Although the light modulation device in which 0 is deformed into a curved surface has been illustrated, the present invention is not limited to this configuration. For example, as shown in FIG. 10A, a mirror element 20C is extended from the support member 80A in substantially one direction, The present invention can be applied to a configuration in which one end in the longitudinal direction is supported in a cantilever state by a support member 80A.

Further, for example, in the above-described embodiment, the configuration in which the mirror element 20 is formed by forming the reflection film 35 on the piezoelectric element 30 is exemplified. However, the present invention is not limited to this.
As shown in FIG. 0 (b), a connection portion with a mirror member is formed near an end of the piezoelectric element 30A supported by the support member 80A in a cantilever state on the opposite side to the support member 80A. The present invention can also be applied to the mirror element 20D provided with 90.

Further, for example, in such a configuration in which the mirror element is supported in a cantilever state, the wiring between the piezoelectric element 30 and the driving element 50 may be extended to the outer peripheral surface of the support member 80A. . That is, as shown in FIG. 11, without providing a through hole in the mirror element 20C and the support member 80A, the lower electrode connection wiring 36A and the upper electrode connection wiring 37A are connected to the mirror substrate 1 via the outer peripheral surface of the support member 80A.
It may be extended up to one level. The lower electrode connection wiring 36A and the upper electrode connection wiring 37A can be easily formed, for example, by sandwiching the third interlayer insulating film 14 as shown in the figure. Also, of course,
These two connection wirings 36A and 37A may be extended to different positions in the circumferential direction of the support member 80A.

The following is an example of the configuration of a light modulation device using a device other than the light-shielding dot array, and an example of the configuration in which the device functions as a convex mirror. Although a configuration in which a mirror substrate is provided on both sides and a configuration in which incident light is made incident via the mirror substrate are not particularly shown, it goes without saying that the configuration can be appropriately selected. Further, the present invention has an effect that a special optical system for condensing incident light on the reflection surface is not required by improving the light condensing performance, but an optical system for condensing incident light may be used. The following shows such a configuration.

FIG. 12 shows the light shielding dot array 1 described above.
A schematic configuration of an optical modulation device provided with a pinhole array 110 and a macro lens array 120 instead of 00 is shown. Here, the pinhole array 110 has a pinhole 111 at a position facing each mirror element 20, and each macro lens array 120 has
Has a convex lens 121 at a position facing the lens. Each pinhole 111 of the pinhole array 110 is provided near the focal point of the deformed mirror element 20B.

In such a light modulation device, the light incident on the deformed mirror element 20B passes through the pinhole 111 of the pinhole array 110 and returns.
Is shielded by the light-shielding portion 112.

That is, in this example, contrary to the above-described example, when the mirror element is deformed, it is ON, and when it is not deformed, it is OFF.

It is to be noted that a light modulating device can be obtained even when the mirror element 20 is deformed to be convex on the side opposite to the mirror substrate 11 to act as a convex mirror. An example of a display device using such a light modulation device will be described later.

In each of the embodiments described above, it is considered that the mirror substrate 11 facing the piezoelectric element 30 is charged when the piezoelectric element 30 is deformed, and the deformation of the piezoelectric element 30 is hindered by the electrostatic force. . Accordingly, in order to solve such a problem, in addition to the above-described configuration, the mirror substrate 11 facing the lower electrode film 32 of the piezoelectric element 30 is set to have substantially the same potential as the lower electrode film 32 facing the piezoelectric element 30. It may be. That is, when the electrodes facing each other are grounded by the common electrode, the substrate is also grounded. Thereby, the electrodes of the piezoelectric element 30 and the mirror substrate 11
No longer occurs due to the potential difference with the mirror element 20.
Is not hindered, and a decrease in the displacement of the mirror element 20 can be suppressed.

For example, an opposing electrode is provided on the mirror substrate 11 opposing the lower electrode film 32, and an electrostatic force is applied between the opposing electrode and the lower electrode film 32 in a direction to assist the deformation of the piezoelectric element 30. A voltage may be applied so as to generate the voltage. In such a configuration, the amount of displacement of the mirror element 20 can be further increased, the light collection rate can be further increased, and the SN ratio can be increased.
The ratio can be improved.

Further, in the above-described embodiment, the wiring to the lower electrode film 32 or the upper electrode film 34 of each mirror element 20 is all extended to the mirror substrate 11 via the support 31a or the support member 80. However, the present invention is not limited to this. For example, only the wiring to the lower electrode film 32 is extended to the mirror substrate 11 via the support portion 31a and the like, and the wiring of the upper electrode film 34 is in contact with a part of the distal end opposite to the support portion 31a and the like. May be provided. In this case, it is needless to say that it is necessary not to hinder the deformation of the piezoelectric element 30.

The light modulation device of the present invention having the above-described configurations is used, for example, as a part of a display device.

FIGS. 13 to 15 show an example of a display device using the light modulation device of the present invention. 13 to FIG.
Reference numeral 5 is a schematic sectional view of an optical system constituting the display device, in which lenses, light modulation devices and the like are drawn in a greatly simplified manner.

The display device shown in FIG. 12 includes a metal halide lamp 210 as a light source and a parabolic reflector 2.
11, a half mirror 220 for causing light from the metal halide lamp 210 to enter the light modulation device 10,
The projection lens 230 includes a projection lens 230 that forms an image of light emitted from the light modulation device 10, and a screen 240 that displays an image formed by the projection lens 230.

This display device has a metal halide lamp 210 as a light source and a metal halide lamp 21.
The light exiting from 0 is reflected by the reflector 211, becomes substantially parallel light, enters the half mirror 220, is reflected by the half mirror 220, and enters the light modulation device 10. The half mirror 220 may be a cube-type half prism.

Among the mirror elements 20 constituting the light modulating device 10, the mirror element 20B which is driven and deformed via the driving element 50 functions as a concave mirror, and the light incident on the deformed mirror element 20B is reflected. Then, the light is condensed toward the light shielding dot 101 and does not return to the half mirror 220 direction. On the other hand, the undeformed mirror element 20
The light incident on A is reflected and is imaged by the projection lens 230 on the screen 240 as an image plane.

With the above-described configuration of the optical system, each mirror element 20 constituting the light modulation device 10 corresponds to a pixel on the screen 240, and the ON / OFF state of the mirror element 20 is determined.
The display image on the screen 240 can be changed depending on the FF, that is, whether the image is not deformed or deformed.

As the screen 240, a reflective screen or a transmissive screen can be used.

In the optical system shown in FIG.
Of the light emitted from 10, only about half of the light emitted from the half mirror 220 illuminates the light modulation device 10, and the other half passes through the half mirror 220 and becomes useless light. Further, only half of the light reflected by the light modulation device 10 passes through the half mirror 220 and passes through the projection lens 230.
Head to. That is, the light that reaches the screen 240 from the light source is attenuated to about 程度 of the light emitted from the light source 210 even if it is ideally estimated that there is no loss on the way.

In the display device shown in FIG. 14, three polarizing beam splitters 22 are used instead of the half mirror 220.
1, 222 and 224, the energy radiated from the light source can be reduced in principle to the screen 240 without any loss.
To lead to.

As shown, light emitted from a metal halide lamp 210 as a light source is reflected by a parabolic reflector 211, converted into substantially parallel light, and enters a first polarizing beam splitter 221. Hereinafter, the polarization beam splitter 221 transmits P-polarized light and reflects S-polarized light.

Since the light emitted from the light source 210 is natural light whose vibration direction is in a random direction, the P-polarized light component (indicated by p in the figure) of the light is transmitted through the first polarizing beam splitter 221, The polarization component (see s in the figure) is reflected. The reflected S-polarized light component is incident on the adjacent second polarization beam splitter 222, where it is reflected and exits the second polarization beam splitter 222 as S-polarized light. On the other hand, the first polarization beam splitter 221
Is converted into S-polarized light by a half-wave plate 223 provided on the emission surface of the first beam splitter 121. Therefore, light incident on the third polarization beam splitter 224 is aligned with S-polarized light.

The light incident on the third polarization beam splitter 224 as S-polarized light is all reflected in the direction of the light modulation device 10, but is reflected by the third polarization beam splitter 224.
Is converted into circularly polarized light by a 波長 wavelength plate 225 provided on the surface of the light modulation device 10
Is incident on.

The light reflected by the reflection film of the mirror element 20 constituting the light modulation device 10 becomes circularly polarized light which is polarized in the direction opposite to the circularly polarized light of the incident light. Then, the light enters the third beam splitter 224. This P-polarized light is supplied to the third beam splitter 224.
In principle, all light is transmitted without being reflected, and reaches the projection lens 230.

As described above, by aligning the vibration directions of the light emitted from the light source, there is no light loss unlike the case where a half mirror is used, and the energy radiated from the light source can be screened without loss in principle. Can be led to. That is, a display device capable of bright display can be configured.

FIG. 15 shows a configuration of a display device according to another embodiment. In this display device, the light shielding dot array 100
And a light modulating device 10A which acts as a convex mirror when each mirror element 20 is driven, and a third polarizing beam splitter 224 of the apparatus of FIG. Beam splitter 22
4 is transmitted through the projection lens 230, while the parallel light is blocked by the lens 250 and the micro mirror 2.
51 is provided. It should be noted that the projection lens 230 reflects light that has passed through the lens 250 with predetermined divergent light on the screen 2.
An image is formed at 40.

In such a configuration, light incident on the undeformed mirror element 20A of the light modulation device 10A is reflected as parallel light and reaches the lens 250. This light is arranged near the focal point of the lens 250. Small mirror 2
The light is condensed and diverged at 51 and does not reach the screen 240. On the other hand, the light incident on the deformed mirror element 20B reaches the lens 250 as divergent light as if it were emitted from the virtual light source 260, and thus reaches the projection lens 230 without being blocked by the micro mirror 251.
0 forms an image on the screen 240.

In the above description, a display device using one light modulation device has been described as a display device. However, as is conventionally known, three light modulation devices are used and each light modulation device is used. It goes without saying that the present invention can also be used as a color display device in which a modulation device modulates each of red, green, and blue lights, and combines and modulates the modulated lights.

[0131]

As described above, according to the present invention, the mirror element is supported by the support member, and the connection wire between the piezoelectric element and the drive element is provided in the support member. An optical modulation device that deforms into a substantially curved surface as a fulcrum can be realized relatively easily. As a result, the change in curvature of the mirror element can be made sufficiently large, and the light collection rate can be significantly improved. Therefore, there is an effect that a sufficient change in curvature can be obtained even if the size is reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a light modulation device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the light modulation device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view schematically showing a driving element according to the first embodiment of the present invention and a wiring diagram of a light modulation device.

FIG. 4 is a plan view schematically showing a driving element according to the first embodiment of the present invention.

FIG. 5 is a sectional view illustrating the method for manufacturing the light modulation device according to the first embodiment of the present invention.

FIG. 6 is a sectional view illustrating the method for manufacturing the light modulation device according to the first embodiment of the present invention.

FIG. 7 is a schematic diagram of an optical system of the light modulation device according to the first embodiment of the present invention.

FIG. 8 is a sectional view of a main part of an optical modulation device according to a second embodiment of the present invention.

FIG. 9 is a sectional view illustrating the method for manufacturing the light modulation device according to the second embodiment of the present invention.

FIG. 10 is a perspective view schematically showing a light modulation device according to another embodiment of the present invention.

FIG. 11 is a sectional view of a main part of a light modulation device according to another embodiment of the present invention.

FIG. 12 is a schematic sectional view of an optical system of a light modulation device according to another embodiment of the present invention.

FIG. 13 is a schematic sectional view of an optical system constituting a display device using a light modulation device according to another embodiment of the present invention.

FIG. 14 is a schematic sectional view of an optical system constituting a display device using a light modulation device according to another embodiment of the present invention.

FIG. 15 is a schematic sectional view of an optical system constituting a display device using a light modulation device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Light modulation device 11 Mirror substrate 20 Mirror element 30 Piezoelectric element 31 Elastic plate 31a Supporting part 32 Lower electrode film 33 Piezoelectric layer 34 Upper electrode film 35 Reflective film 36 Lower electrode connection wiring 37 Upper electrode connection wiring 40 Through hole 50 Driving element 53 Drive wiring 54 First signal line 55 Second signal line 80 Support member

Claims (22)

[Claims] 1. A mirror element having a piezoelectric element including a piezoelectric layer and first and second electrodes sandwiching the piezoelectric layer and having a mirror film structure for reflecting light, and provided corresponding to the mirror element. A driving element, wherein the piezoelectric element is fixed on a substrate via a support member provided on one surface side, and the piezoelectric element is connected to the first and second electrodes. The light modulation device, wherein the wiring extends to the driving wiring provided on the substrate via the support member. 2. The piezoelectric element according to claim 1, wherein the piezoelectric element extends two-dimensionally from a connection portion with the support member, and a substantially central portion thereof is a connection portion with the support member. A light modulation device characterized by being deformed into a curved surface with a portion as a fulcrum. 3. The piezoelectric element according to claim 1, wherein the piezoelectric element extends substantially in one direction from a connection portion with the support member, and is supported in a cantilever state by the support member at one longitudinal end thereof. A light-modulating device, wherein the tip portion is deformed in the thickness direction with the connection portion as a fulcrum by driving. 4. The light modulation device according to claim 1, wherein the piezoelectric element has an elastic plate on the one surface side. 5. The light modulation device according to claim 1, wherein the piezoelectric element has the mirror film structure on the other surface side. 6. The light modulation device according to claim 5, wherein the mirror film structure of the piezoelectric element is constituted by the second electrode on the other surface side or a reflection film provided thereon. device. 7. The piezoelectric element according to claim 4, wherein a mirror member constituting the mirror film structure is provided at a longitudinal end of the piezoelectric element opposite to the support member, and the mirror element is driven by driving the piezoelectric element. An optical modulation device, wherein an inclination angle of a reflection surface of a mirror member changes. 8. The piezoelectric element according to claim 1, wherein at least a part of a region of the piezoelectric element facing the support member is removed to form a piezoelectric element removing portion, and at least the other surface side of the piezoelectric element. A light modulation device, wherein a connection wiring for connecting the electrode and the corresponding driving wiring is provided in the piezoelectric element removing section. 9. The light modulation device according to claim 8, wherein the piezoelectric element removing portion is a through hole penetrating the piezoelectric element in a thickness direction. 10. The supporting member according to claim 8, wherein the supporting member is an annular member having a supporting member penetrating portion provided on the substrate, and the piezoelectric element removing portion communicates with the supporting member penetrating portion. An optical modulation device, comprising: 11. The connecting wire according to claim 10, wherein a connecting wire for connecting at least the electrode on the other surface side of the piezoelectric element and the corresponding driving wire is provided in the support member penetrating portion. Light modulation device. 12. The light modulation device according to claim 1, wherein the support member is formed by projecting a layer constituting the one surface of the piezoelectric element toward the substrate. device. 13. The device according to claim 12, wherein a layer forming the support member is an electrode on the one surface side of the piezoelectric element, and the electrode is electrically connected to the connection wiring. Light modulation device. 14. The connection wire according to claim 8, wherein each of the connection wires connecting each of the first electrode and the second electrode and the drive wire is provided in the support member penetrating portion. A light modulation device, wherein the light modulation device is arranged so as to be separated in a plane. 15. The connecting wire according to claim 8, wherein the connecting wire connecting each of the first electrode and the second electrode to the driving wire is insulated in the support member penetrating portion. A light modulation device, wherein the light modulation device is formed by stacking layers. 16. The light modulation device according to claim 14, wherein the surface of the electrode on the one surface side of the piezoelectric element near the end on the piezoelectric element removal portion side is exposed. 17. The device according to claim 1, wherein the connection wiring extends outside the support member via a connection portion between the support member and the piezoelectric element. Light modulation device. 18. The driving wire according to claim 1, wherein the driving wiring extends to an upper surface of an island member provided in an island shape constituting the supporting member, and the driving wire extends inside the piezoelectric element removing portion. An optical modulation device, wherein a driving wiring is exposed, and the connection wiring is connected to the exposed driving wiring. 19. The light modulation device according to claim 18, wherein the height of the upper surface of the island member and the height of the lower surface of the piezoelectric element are substantially the same. 20. An optical modulator according to claim 1, wherein said substrate is a silicon single crystal substrate, and said driving element is constituted by a semiconductor integrated circuit provided on said substrate. device. 21. The light modulation device according to claim 1, wherein the mirror elements are arranged in a two-dimensional array. 22. The light modulation device according to claim 1, a light source, and light from the light source being incident on the light modulation device and driving or not driving the piezoelectric element of the light modulation device. An optical system that emits only one of the reflected lights.