JP2001269992A - Transfer mold, and method for producing fine structure and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technical method which separates pixels simply in a device that forms a fine structure by means of mold transfer and makes movement by pixel unit. SOLUTION: On a transfer mold 70 to be used to form an optical element 3 as a pixel, a face 72 which regulates a surface 3a of the optical element 3 and a projection 74 for separation capable of forming a clearance 47 for separating by pixel unit are arranged. Therefore, when the transfer mold 70 is removed, the upper face of the optical element 3 is formed and at the same time the clearance 47 for separation is formed also. So, an etching process for forming the clearance 47 for separating by pixel unit can be omitted, and the fine structure which needs high dimensional accuracy can be produced highly accurately and simply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro-replica technique for forming a resin microstructure using mold transfer.

[0002]

2. Description of the Related Art In recent years, the size of video projection devices such as data projectors and video projectors has been further reduced, and the size of video display devices has been extremely reduced. For this reason, optical elements on the order of microns or sub-microns and video display devices equipped with the same have been developed. Similarly, in optical communication, optical arithmetic, optical recording devices such as hologram memories, optical printers, and the like, devices for systems requiring high resolution and high-speed response require microstructures on the order of microns or even smaller submicrons (microstructures). The development of an optical device equipped with a) has been earnestly advanced.

[0003]

FIG. 1 shows an outline of an image display device (evanescent light switching device) which modulates light using an evanescent wave (evanescent light) which is being developed by the present applicant. is there. The video display device 50 is a device in which a plurality of optical switching elements (optical switching mechanisms) 10 are two-dimensionally arranged on a substrate 20. Individual optical switching element 10
Is an optical element 3 capable of modulating light by approaching and moving away from a light guide plate (light guide) 1 capable of totally reflecting and transmitting the introduced light 2, and an actuator 6 for driving the optical element section 3. And By manufacturing an optical element (micro-optical element) and an actuator (micro-actuator) on the order of microns, an optical element is formed on a semiconductor substrate 20 on which a drive circuit for driving the actuator and a digital storage circuit (storage unit) are built. The layer of the element 3 and the layer of the actuator 6 can be laminated, and a chip-sized device integrated as one image display device can be provided.

[0004] The image display device 50 of the present example using evanescent light will be described in more detail. To explain based on the individual optical switching elements 10, FIG.
The optical switching element 10a shown on the left side is in an on state, and the optical switching element 10b shown on the right side is in an off state. The optical element 3 has a surface (contact surface or extraction surface) 3a that is in close contact with the surface (total reflection surface) 1a of the light guide plate 1 (light guide) that functions as a waveguide, and this surface 3a is the total reflection surface 1a. The V that extracts the evanescent wave that leaks out when it comes into close contact with the light guide plate 1 and reflects the evanescent wave inside the light guide plate 1
-Shaped reflection prism (micro prism) 4 and this V
And a V-shaped groove support structure 5 for supporting the V-shaped prism 4.

The actuator 6 is capable of electrostatically driving the optical element 3. An upper electrode 7 to which a support structure 5 of the optical element 3 is mechanically connected, and a lower electrode 8 opposed to the upper electrode 7. And And the lower electrode 8,
The anchor plate 9 of the upper electrode 7 is disposed on the uppermost surface 20a of the semiconductor substrate 20. The upper electrode 7 is supported by a support 11 extending upward from the anchor plate 9,
A space is formed between the lower electrode 8 and the upper electrode 7. Therefore, for example, when the upper electrode 7 is grounded via the plate 9 and a potential or an electric charge is applied to the lower electrode 8 from the drive unit 21 (hereinafter referred to as a high potential), the upper electrode 7 moves downward and interlocks with this As a result, the optical element section 3 is separated from the light guide plate 1 (second position). On the other hand, the upper electrode 7 partially has a function as an elastic member, and the potential or charge applied to the lower electrode 8 from the drive unit 21 is removed or released (hereinafter, low potential).
Then, the upper electrode 7 is separated from the lower electrode 8, and the optical element unit 3 is brought into close contact with the light guide plate 1 by the elasticity of the upper electrode 7 (first position).

As shown in FIG. 1, illumination light 2 is supplied to a light guide plate 1 from a light source at an angle at which the illumination light 2 is totally reflected by a total reflection surface 1a. Light is repeatedly totally reflected on the side 1a facing the light switching portion 3 and on the upper surface (emission surface), and the inside of the light guide plate 1 is filled with light rays. Therefore, in this state, the illumination light 2 is macroscopically confined inside the light guide plate 1 and propagates therein without any loss. On the other hand, microscopically, in the vicinity of the surface 1a of the light guide plate 1 which is totally reflected, the illumination light 2 leaks from the light guide plate 1 only for a very short distance of about the wavelength of light, and changes its course. The phenomenon of returning to the inside of the light guide plate 1 again occurs. The light leaked from the surface 1a in this manner is generally called an evanescent wave. This evanescent wave
It can be taken out by bringing another optical member close to the total reflection surface 1a at a distance of about the wavelength of light or less. The optical switching element 10 of the present embodiment is designed to modulate light transmitted through the light guide plate 1 at high speed, that is, to switch (on / off) using this phenomenon.

Therefore, in the optical switching element 10a, since the optical element 3 is at the first position in contact with the total reflection surface 1a of the light guide plate 1, evanescent waves can be extracted by the surface 3a of the optical element 3. For this reason, the light 2 extracted by the microprism 4 of the optical element 3 is changed in angle and becomes the output light 2a. On the other hand, the optical switching element 10
In b, voltages having different polarities are applied to the upper and lower electrodes 7 and 8 by the drive unit 21, and these electrodes 7 and 8 are applied.
The optical element 3 is moved to the second position apart from the light guide plate 1 by the electrostatic force acting during the period. Therefore, the evanescent wave is not extracted by the optical element 3, and the light 2 does not exit from the inside of the light guide plate 1.

An optical switching element using an evanescent wave functions as a device capable of switching light by itself. However, as shown in FIG.
It is configured so that it can be arranged in a three-dimensional direction, or even three-dimensionally. In particular, by arranging two-dimensionally in a matrix or array, it is possible to provide a video display device or an image display unit 55 capable of displaying a two-dimensional image similarly to liquid crystal or DMD. In the image display device 50 using evanescent light, the moving distance of the optical element 3 is on the order of submicron, so that it can be used as a light modulator having a response speed one digit or more faster than that of liquid crystal. Alternatively, a direct-view image display device can be provided. Further, the optical switching element 10 using evanescent light can turn on and off light by almost 100% with a movement on the order of submicron,
An image with very high contrast can be expressed. For this reason, it is easy to increase the temporal resolution, and a high-contrast image display device can be provided.

Further, as described above, an image display device 50 having a configuration in which the actuators 6 and the optical elements 3 arranged in an array on the semiconductor integrated substrate 20 in which the drive circuit and the like are built is provided in one chip. It is possible to That is, the image display unit 55 can be supplied by assembling the image display device 50, which is a micromachine or an integrated device, in which a microstructure such as the actuator 6 and the optical element 3 is constructed on the semiconductor substrate 20, and the light guide 1. By incorporating the above, it is possible to provide a projector which can display a high-contrast image with a high operation speed and a high resolution.

The switching device using the evanescent light is not limited to the one shown in FIG. 1. For example, in addition to the upper electrode 7 and the lower electrode 8, an intermediate electrode moving between them is provided, and the intermediate electrode is interlocked with the intermediate electrode. An image display device having an actuator 6 configured to drive the optical element 3 is also possible. The video display device using the evanescent light has a merit that the configuration of the actuator 6 is complicated but can be driven at a low voltage. Furthermore, instead of electrostatic actuators using electrodes,
It is also possible to form an actuator using a piezo element, and several actuators have been considered. Therefore, in the following description, the description will be made based on an actuator of an electrostatic drive type with upper and lower electrodes for simplicity, but the configuration of the actuator is not limited to this.

An image display device using evanescent light has excellent characteristics as described above. However, there are several problems to be solved in order to put this video display device into practical use, and one of them is to improve the yield and reduce the cost. That is, since each optical switching element constituting the video display device displays a pixel, if there is a defect, the image quality deteriorates. Therefore, it is important to manufacture a video display device having no pixel defect or a high yield. In addition, by improving the yield, it is possible to provide a product free from pixel defects at low cost. An image display device using evanescent light is of a type in which a large number of micro optical elements are driven by an actuator as described above, and turns on / off light by a submicron-order movement or less with respect to a total reflection surface. Therefore, a micro optical element having high dimensional accuracy is required, while speeding up is easy. Further, it is necessary to manufacture a micro optical element using a material having excellent optical properties such as excellent light transmittance.

In order to satisfy these requirements, the inventors of the present application have developed a micro-replica technique for forming a micro-structure by transferring a mold to a resin layer. In this manufacturing method using mold transfer, a resin material is sandwiched between two substrates (one substrate is a mold for transferring the shape), and while applying pressure from both sides or after applying pressure, light or heat is applied. By curing, a resin layer having a shape of a predetermined micron order or less is formed.

The resin layer formed by this manufacturing method is separated into units constituting individual pixels so as to be optical elements of an optical switching element array used for an image display device or the like, and can be driven by an actuator. There is a need. For this reason, when separating the layer formed of resin, in a substantially vertical direction toward the supporting substrate,
The resin layer is dug (etched) by plasma etching or the like. Then, a gap is formed between the individual optical elements constituting the pixel to separate them.

However, in the case of a fine structure requiring dimensional accuracy on the order of microns or submicrons, such a separation method causes damage (load) not only to an etching portion for separating pixels, but also to the periphery. Can be In particular, if damage is given to a portion that affects the performance of a pixel, quality will be reduced. Therefore, this causes a reduction in the quality and yield of the video display device.
Further, there is a possibility that variations occur, such as the accuracy of the etched separation grooves (gap) being difficult to obtain.

That is, in the above-described image display device, when separating pixels, in order to increase the reflection efficiency of incident light and form a bright image, it is desirable that the dimension between pixels is as small as possible. On the other hand, in order to drive pixels individually, it is necessary to prevent adjacent optical elements from interfering with each other. Therefore, it is necessary to form a gap as thin as possible with high precision by etching for separation. Although a gap for pixel separation can be formed by oxygen plasma etching or the like, it is necessary to perform very deep etching on a mask that defines a layout for patterning the gap, and it is easy to overetch. Therefore, the gap on the mask side becomes large. on the other hand,
When the opening of the mask is narrowed, the clearance for the pixel becomes insufficient, and there is a possibility that a portion where the optical element does not move may occur, and the yield decreases.

As described above, it is difficult to control a desired dimensional accuracy by a separation method using plasma etching or the like. Therefore, in order to mass-produce high-precision switching elements or devices by micro-replica technology,
A simpler, higher yielding separation method is needed.

The micro-replica technique can be applied not only to the optical switching element but also to other purposes, for example, a technique for manufacturing a micromachine for switching a microvalve. Therefore, there is a problem similar to the above when separating the movable part.

In view of the above, an object of the present invention is to provide a technique capable of separating a movable piece accurately and easily when manufacturing a movable piece including a micro optical element by a micro replica technique.

[0019]

When a microstructure of micro order or submicron order is manufactured by using a mold transfer, in a conventional transfer mold, the upper surface of a movable piece, for example, an optical system using a prism as a movable piece is used. In the case of an element, only the surface on which the prism is formed is formed. In contrast, in the present invention, up to a separation projection capable of forming a gap for separating the movable piece is provided. By molding using such a transfer mold, when the transfer mold is removed, the upper surface of the movable piece is formed, and at the same time, a separation gap can be formed.

That is, according to the method of the present invention for producing a microstructure in which a plurality of movable pieces are arranged in an array on a substrate, the method comprises the steps of: applying a first resin to be a movable piece on a substrate; The method includes a step of pressing a transfer die having a plurality of separation projections forming a gap capable of separating one resin in units of a movable piece to form at least a part of the movable piece.

Therefore, a gap for separating the movable piece is generated only by removing the transfer mold. Therefore, separation can be performed without performing oxygen plasma etching or the like, and the above-described problem due to etching can be avoided. That is, it is possible to reduce damage to a portion that affects the performance of the microstructure by over-etching or the like, and it is possible to reliably secure a clearance where each movable piece can operate.

Even if a small amount of resin remains in the separation space after the transfer mold is removed, a slight etching may be performed. Therefore, damage to the surroundings can be considerably reduced as compared with the conventional method of etching all elements, and element isolation can be performed with high accuracy in a short time.

Therefore, according to the present invention, in a microstructure requiring dimensional accuracy on the order of microns or submicrons, the separation method of the present invention facilitates management of dimensional accuracy in separating the movable piece. Thus, by applying the present invention, by a simple separation method,
Since the yield can be improved, the present invention is effective as a manufacturing method for mass-producing high-precision switching elements or devices by micro-replica technology.

In addition, according to the manufacturing method of the present invention, since the movable pieces can be easily and accurately separated from each other, a micromachine that switches not only the optical switching element but also other objects as described above is manufactured. It can also be applied as technology.

According to the manufacturing method of the present invention, it is possible to manufacture an image display device in which a movable piece is configured in pixel units. Then, an actuator array layer in which microactuators for driving the movable piece are two-dimensionally arranged on the substrate is provided, and the movable piece is formed by applying the first resin on the actuator layer to form the movable piece. Can be driven. In the case of an image display device, a micro optical element capable of turning on and off incident light is suitable as a movable piece. Further, in the case where a V-shaped prism that reflects the incident light by changing the angle of the incident light is provided on the movable piece, in the molding step, the first resin is stacked on the actuator layer to form a V-shaped groove. Process and the second in the V-shaped groove
And a second step of forming a prism by applying the resin.

The transfer type used in the first step is V
A plurality of inverted V-shaped molding projections that define a U-shaped groove are provided. By using a transfer mold in which separation projections are formed at the valleys of these molding projections, a pixel is formed. The separation gap can be formed at the same time as the V-shaped groove is formed.

The transfer mold used in the second step is as follows:
It has a molding surface that defines the upper surface of the prism, but by using a transfer mold in which projections for separation are formed perpendicular to the molding surface, a prism is formed and a gap for pixel separation is formed at the same time. can do. Therefore,
These first and second steps, and further, by using a transfer mold on which a projection for pixel separation is formed, individual optical elements constituting a pixel can be molded in a separated state, and the step of element separation is omitted. it can.

As described above, when manufacturing using a plurality of transfer dies, the width of the separation projection of the second transfer mold is made smaller than the width of the separation protrusion of the first transfer mold. It is desirable to provide. Thus, the separation projections formed on the respective transfer molds can be smoothly arranged at predetermined positions where the gaps for separation are formed.

In the above-described manufacturing method for manufacturing an image display device in which micro optical elements are arranged in an array as a movable piece such as an image display device using evanescent light, an actuator array in which micro actuators are arranged in an array A step of manufacturing a layer on a substrate, and a step of manufacturing an optical element array layer in which micro-optical elements are arranged in an array on the actuator array layer, and in the step of manufacturing the optical element array layer, After applying a first resin on the actuator array layer, a transfer mold having a plurality of separation protrusions forming a gap separable in units of micro optical elements is pressed against the first resin, By forming an optical element array layer having a plurality of micro optical elements arranged in a plane, the yield is high, and the yield is high. The quality of image display device can be realized by the production method of the present invention.

Further, if an electrostatic actuator is used as the microactuator and a microprism is used as the micro optical element that performs optical switching by evanescent light, a video display device using evanescent light can be realized with a very high yield at low cost. A manufacturing method can be provided.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to a method for manufacturing an optical switching device 50 using evanescent light shown in FIG.

First, as shown in FIGS.
Then, a layer to be the actuator 6 is manufactured on the “0”. As shown in FIG. 2, an electrode layer (Al film) 31 is deposited on the upper surface 20a of the substrate 20 on which the CMOS is formed. Next, the electrode layer 31 is patterned 41 to form a lower electrode 8 and an anchor portion 9 having a structure also serving as a spring and an upper electrode.
To form

As shown in FIG. 3, a sacrificial layer 32 is deposited on the electrode layer 31. The sacrificial layer 32 is made of amorphous silicon and can be deposited at a temperature of several tens of degrees Celsius to one hundred and several tens degrees Celsius, and a CMOS formed on the underlying semiconductor substrate 20 is formed.
No damage to the circuit. Dimples 42 serving as stoppers are dug in the sacrificial layer 32,
The portion to be a post is patterned 43.

As shown in FIG. 4, on the sacrificial layer 32, a second electrode layer (Al film) 33 serving as a second structural layer for forming the structure 7 serving as a spring and an upper electrode is deposited. I do. Further, the electrode layer 33 is patterned to form the upper electrode 7 and the post 11. At this stage, a structure as the actuator section 6 is formed on the semiconductor substrate 20. The combination of the materials constituting the sacrificial layer and the electrode layer is not limited to the above. For example, the sacrificial layer may be formed of polyimide instead of amorphous silicon. It is also possible to use silicon oxide for the sacrificial layer and polysilicon for the electrode layer.

Further, as shown in FIG. 5, a second sacrifice layer 34 is deposited on the second electrode layer 33 with the same material as the first sacrifice layer 32, and is patterned. A connection portion 44 with the micro optical element 3 is formed thereon. Up to this stage, the actuator 6
A microstructure layer (actuator array layer) 25 that functions as a layer is formed.

Next, the optical element 3 to be a movable piece is formed on the actuator array layer 25 by mold transfer.
6 to 10 show an outline of a process of manufacturing an optical element array layer functioning as the optical element 3 by die transfer. First, as shown in FIG. 6, a resin (first resin) 35 is applied on the actuator array layer 25 to form a support structure 5 having a V-shaped groove for supporting the microprism 4 of the optical element 3. To manufacture. For this reason, the inverted V-shaped forming projection 6 is formed on the resin 35 in advance by etching or the like.
The transfer mold 60 provided with 2 is assembled and pressure is applied. Then, the resin layer 35 having a desired shape is formed by irradiating ultraviolet rays or the like to perform photopolymerization. This process is 2P (Photo-polyme
r) Since it is known as a method, detailed description is omitted. In the present embodiment, as the resin layer 35, a fluorinated resin or a photopolymerized resin is used, and is transparent to light such as ultraviolet rays. The shape of the letter-shaped support structure 5 is manufactured by a photo-curing process.

Further, as shown in FIG. 7, after the resin layer 35 is formed, the transfer mold 60 is removed. Then, a reflective film 46 is deposited on the mold-formed support structure 5 by a method such as depositing aluminum on a portion to be the bottom surface of the microprism 4.

The cross section of the first transfer mold 60 of this embodiment is substantially M
It is shaped like a letter. That is, V-shaped support 5
In the first transfer die 60 for forming the above, a molding surface 62b is formed by a plurality of inverted V-shaped molding projections 62 that define a V-shaped groove. The molding surface 62a forms the surface of the support 5, that is, the surface that defines the shape of the bottom of the microprism 4.

Further, plate-shaped separation projections 64 extending in the same direction as the molding projections 62 are formed in the valley portions 63 of these molding projections 62. Therefore, when the first transfer mold 60 is aligned with the resin layer 35, a space (space) 47 for separating the V-shaped portion is formed in the resin layer 35 by the projection 64. In this example,
Since a prism having a V-shaped bottom constitutes one pixel, a projection 64 for separating elements or pixels is provided at a valley portion 63 of a projection 62 for molding.

Next, as shown in FIG. 8, a second resin 36 is applied after the reflective film 46 is deposited, and a second transfer mold 7 is formed.
The micro prism 4 is formed by using 0. Since the surface of the microprism 4 becomes the surface 3a from which evanescent light is extracted, it is necessary to form the microprism 4 with high precision. Therefore, a flat surface (molding surface) 7 for molding the surface 3a of the prism.
The mold is formed by applying pressure using the second transfer mold 70 provided with the second transfer mold 2. The microprism 4 is also suitable for the microprism by using a photocurable (photopolymerizable) resin as the second resin 36 for molding and using a transfer mold 70 that is transparent to light such as ultraviolet light, as described above. The shape can be manufactured by a photocuring treatment (2P method).

Since the optical element array layer 26 is formed by molding with the second transfer mold 70, the second transfer mold 70 is removed as shown in FIG. Second transfer mold 70
Also, a projection 74 for pixel separation is provided at a position that matches the groove 47 for element separation formed in the above process.
For this reason, the layer 26 in which the optical elements 3 are arranged in an array is formed by the second transfer mold 70, and at the same time, the individual optical elements 3 are placed in the gaps 47 formed by the projections 74 of the transfer mold 70. It will be in a separated state. That is, the prism 4
Is formed, the gap 47 for pixel separation is not filled with the resin 36, and the gap 47 is also formed by the second transfer mold 70 at the same time. Therefore, in the manufacturing method of this example, a step of newly performing oxygen plasma etching or the like can be omitted in order to provide the gap 47 for separating the pixel unit.

Thereafter, as shown in FIG.
The sacrificial layers 32 and 34 made of amorphous silicon are removed through the gap 47 formed by the steps 70 and 70 by a method such as dry etching using xenon fluoride (XeF2) gas or the like. This makes it possible to completely remove the sacrificial layer without causing the problem of adsorption even in a narrow gap between the electrodes or the like, and to reliably form the driving space 12 between the electrodes. Therefore, a reliable actuator 6 can be realized.

Thus, the optical element 3 having the microprisms 4 driven by the individually separated actuators 6 can be formed. The device manufactured by the manufacturing method of the present embodiment is a video display device 50 in which the actuator 6 and the optical element 3 which are microstructure layers are vertically stacked on the semiconductor substrate 20. By combining with the light plate 1, it is possible to provide the video display unit 55 based on the technology of the optical switching element 10 using the evanescent light described with reference to FIG.

As described above, in the manufacturing method of this embodiment,
A gap for separating the optical element is formed at the same time as defining the surface of the optical element serving as a pixel by the transfer mold. Accordingly, the thin gap 47 for separation can be accurately formed at the same time when the surface as the optical element is formed without damaging the periphery of the optical element. For this reason, it is possible to avoid damage around the optical element that may occur when the pixel separation is etched. Further, since the gap 47 is also molded, the dimensional accuracy of the shape is high, and there is no possibility that the gap is excessively widened by over-etching or the like. Therefore, even in the case of a microstructure requiring dimensional accuracy on the order of microns or submicrons, the optical element can be made as large as possible and sufficient clearance can be obtained by forming gaps that separate at the same time when transferring the mold. It is possible to manufacture a switching element or a device that can reliably move by forming a gap so as to secure it. For this reason, according to the manufacturing method of the present invention, it is possible to manufacture a video display device capable of outputting a bright image with high utilization efficiency of incident light. Further, since a narrow gap can be formed with high accuracy, the yield can be improved and the manufacturing cost can be reduced.

In the above manufacturing method, the optical element 3 as a movable piece is formed in two steps using two transfer dies. For this reason, in the second transfer mold 70 of the present example, the separation projection 74 is formed perpendicular to the flat molding surface 72 together with the substantially flat molding surface 72 that defines the upper surface of the prism 4. In the previous process (see FIG. 7), the first transfer mold 6
It is necessary to adjust the projection 74 of the second transfer mold 70 to the gap 47 provided in the resin layer 35 due to 0. That is, the gap 47 formed by the first transfer die 60
In addition, it is desirable that the separation projection 74 of the second transfer mold 72 fits into the second transfer mold 72. Therefore, the projection 74 of the second transfer mold 70 is larger than the width W1 of the protrusion 64 of the first transfer mold 60.
Is desirably provided with a small width W2. Thus, the gap 47 can be smoothly secured between the resin layers 35 and 36 by the two transfer dies 60 and 70.

As described above, when the optical element 3 is formed by mold transfer in two stages, the projection 64 is formed in the same portion.
And 74 are disposed so that the separation gaps 47 can be easily formed later simply by removing the transfer molds 60 and 70.
Can be formed. Therefore, the separation step and the step of molding the movable piece (optical element) 3 can be simplified.

According to the manufacturing method of the present invention, it becomes very easy to separate pixels in a device (optical switching element array) using evanescent light, and the accuracy is improved and the yield is increased. Therefore, it is possible to provide a device using evanescent light as a technology that can be actually mass-produced. The optical switching element device using the evanescent light can be applied not only to an image display device but also to various devices such as an optical computer and an optical printer. Furthermore, in the manufacturing method of this example, the micro replica technology is not limited to the optical switching element. The present invention can be applied to other purposes, for example, a technique for manufacturing a micromachine for switching a microvalve.

Here, referring to FIGS. 11 to 14,
The molding process of the transfer die 60 of this example will be described. In the following, an example is described in which a master of the transfer mold 60 is first formed by lithography technology, and the transfer mold is manufactured using the master as a mold. However, the method of manufacturing the transfer mold is not limited to this.

As shown in FIG. 11A, the cleaned silicon substrate 80 is thermally oxidized to form an oxide film 81 on the surface as shown in FIG. 11B. As shown in FIG. 11C, a resist (photosensitive organic polymer) solution is dropped, and a resist film 82 having a thickness of about 1 μm is formed by spin coating or the like. Then, as shown in FIG. 11D, a photomask having a desired shape is applied, and ultraviolet rays are irradiated for several seconds to pattern the resist 82 into a predetermined shape. Next, FIG.
As shown in FIG. 3A, the oxide film 81 is etched using the resist 82 as a mask (silicon oxide etching).
I do. Then, the resist is peeled off as shown in FIG. Thereafter, as shown in FIG. 12C, anisotropic etching (wet etching) of the 110 plane of silicon is performed.
Thereby, a V-shaped groove 83 of 30 ° is formed. Then, as shown in FIG. 12D, the silicon oxide film 81 is peeled off.

Further, FIGS. 13 (a) to 13 (c)
As shown in the drawing, similarly to the steps shown in FIGS. 11B to 11D, the surface is thermally oxidized, a resist is applied, and the surface is exposed to ultraviolet rays, exposed and developed, and etched. Then, a resist layer 82 is formed so as to cover the V-shaped groove 83, and a portion 82a where each V-shaped groove 83 is connected, which is a place for forming a separation projection, is patterned. Further, as shown in FIGS. 13D to 14B, the oxide film 83 is removed using the resist 82 as a mask.
Further, a concave portion 84 is formed by vertically digging a place 82a patterned by a method such as plasma etching. Thus, the first transfer-type master 90 is manufactured.
Then, the recess 84 corresponds to the separation projection 64 in the first transfer die 60 formed by the first master 90. Finally, a resin is applied to the formed master 90 to obtain the first transfer mold 60 having the separation projection 64 as shown in FIG.

A method of manufacturing the second transfer mold 70 will be described with reference to FIGS. The second transfer mold 70 of this embodiment is a step-type mold having a portion 72 that defines the upper surface of the optical element (prism) 4 and a projection 74 that forms a space that can be separated into each pixel. Similarly, first, the master disc 92 is formed. Master 9 for forming transfer mold 70 of this example
2 uses quartz glass 84. As shown in FIG. 15B, Cr / Au sputtering is performed on the surface of the quartz glass 84 to form a Cr / Au layer 85 serving as a mask. As shown in FIG. 15C, a resist 86 is applied to the Cr / Au layer 85, irradiated with ultraviolet rays as shown in FIG. 15D, exposed and developed, and a portion for forming a projection for separation is formed. 86a is patterned. Further, as shown in FIG. 15E, the Cr / Au layer 8 is formed using the resist 86 as a mask.
5 is etched to form a pattern for forming separation projections on the Cr / Au layer 85.

Further, as shown in FIG. 16A, the resist layer 86 is removed, and then, as shown in FIG.
Using the r / Au layer 85 as a mask, the glass substrate 84 is etched to form a recess 88 having an appropriate depth. FIG.
In (c), a resist is applied again to form a resist layer 86, and in FIG. 16 (d), a portion 86b for forming a step portion defining the thickness of the prism is patterned. In FIG. 17A, Cr /
The Au layer 85 is etched to form a step portion,
In FIG. 17B, the resist layer is removed. As a result, a portion 86b forming a step and a dent or groove portion 88 forming a separation projection appear. In FIG.
Etching is performed using the r / Au layer 85 as a mask. As a result, a groove 88 and a stepped portion 89 having a predetermined depth are formed on the master disk 92.

Further, as shown in FIG.
The master layer 92 is completed by removing the Au layer 85. As shown in FIG. 17E, a transfer die 70 having a step 75 for defining the thickness of the prism can be obtained by applying a resin to the master disc 92 as shown in FIG. it can.

In the manufacturing method of the present embodiment, when manufacturing the fine structure, the gap 47 is formed to separate the fine structure by the transfer molds 60 and 70 for each pixel, and the fine structure is formed into the state of the movable piece by molding. Molded up to. To this end, first and second transfer molds 60 and 70 having separation protrusions or thin walls 64 and 74 are employed, and such transfer molds can be manufactured by the above-described process. it can. Therefore, in the manufacturing method of this example, at the stage where the transfer dies 60 and 70 are removed, the support structure 5 and the microprism 4 are formed, and at the same time, the gap 47 for pixel separation is formed. The provided optical element 3 is molded as a movable piece. Therefore, it is not necessary to perform oxygen plasma etching or the like in order to provide a gap for separating pixels. For this reason, damage to the optical element 3 and the like, which affects the performance of the image, is reduced, and the quality, yield, and workability of the optical switching element 10 and the video display device 50 can be improved. In addition, since the process is simplified, the manufacturing cost can be reduced in this respect as well.

After the transfer dies 60 and 70 are released, the separation gap (space) 47 may not be completely completed. For example, some resin 35 and 36
May be left. Compared to the case where all of the gap 47 is subjected to oxygen plasma etching, the effect on the optical element 3 is very small and the etching time may be short if plasma etching is performed on a slightly remaining portion. Therefore, the manufacturing process can be shortened, and a product with a high yield can be manufactured.

In the device using the evanescent light of this example, the optical element array layer 26 is divided into two parts and molded using two types of transfer dies 60 and 70.
However, the present invention is not limited to this. Even when one or three or more transfer dies are used to manufacture an optical element or other switching elements, it is possible to provide a projection for forming a space for separation in those transfer dies. The separated movable piece can be formed in the same manner as described above. In addition, the shape of the optical element formed by the transfer mold is not limited to the above example, and an optical element having a microlens or the like can be similarly formed.

In the above description, an electrostatic actuator and an optical switching element in which optical elements are vertically stacked on a semiconductor substrate have been described as an example, but other electromechanical effects such as a piezo effect can be used. Even a switching device having a conventional actuator can be manufactured by the present invention. In addition, the switching target of the optical element is not limited to the evanescent wave, and an optical element array that performs a switching operation using another optical system, for example, a reflection optical system can be manufactured in the same manner. Of course, the switching target is not limited to light, but may be another medium such as a fluid.

[0058]

As described above, according to the present invention, when a microstructure of micro order or submicron order is manufactured using a transfer mold, a gap for separating a movable piece is formed in the transfer mold. By providing a separation projection that can be formed, the upper surface of the movable piece can be formed only by mold transfer, and the movable piece can be separated. Therefore, it is possible to obtain a separated state for each movable piece without performing etching for separating after molding, and it is possible to avoid damage accompanying etching for separating the movable piece. In addition, since the separation groove can be formed by molding, the accuracy is improved and the yield is improved. Further, since the etching step can be omitted, the manufacturing step can be shortened. Therefore, according to the manufacturing method of the present invention, a movable piece including a micro-optical element can be manufactured accurately and at low cost even in a fine structure requiring a dimensional accuracy of a micron order or a submicron order. Devices can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a video display device using evanescent light.

FIG. 2 is a diagram illustrating a manufacturing process of the optical switching element illustrated in FIG. 1, illustrating a state in which a first electrode layer is formed on a semiconductor substrate.

FIG. 3 is a diagram illustrating a manufacturing process of the optical switching element illustrated in FIG. 1, illustrating a state in which a first sacrificial layer is formed on a first electrode layer.

FIG. 4 is a view illustrating a process of manufacturing an actuator on a semiconductor substrate, and is a view illustrating a state in which a second electrode layer (spring layer) is formed on a first sacrificial layer.

FIG. 5 is a diagram showing a state in which a second sacrificial layer is formed on a second electrode layer on a semiconductor substrate.

FIG. 6 is a diagram showing how a support structure is formed by mold transfer.

FIG. 7 is a view showing a state where a first transfer mold used in FIG. 6 is removed and a reflection film is formed.

FIG. 8 is a diagram showing a state in which a micro prism is formed by mold transfer.

FIG. 9 is a view showing a state where a second transfer mold used in FIG. 8 is removed.

FIG. 10 is a diagram showing a state in which the optical switching element is manufactured by removing the sacrificial layer.

FIG. 11 is a cross-sectional view showing a manufacturing process of a master for molding a first transfer die according to the present invention.

FIG. 12 is a cross-sectional view showing a step after the manufacturing process of the master forming the first transfer die shown in FIG. 11;

13 is a cross-sectional view showing a step after the manufacturing process of the master forming the first transfer die shown in FIG. 12. FIG.

14 is a cross-sectional view showing a step after the manufacturing process of the master for forming the first transfer mold shown in FIG. 13;

FIG. 15 is a cross-sectional view showing a manufacturing process of a master for molding a second transfer die according to the present invention.

16 is a cross-sectional view showing a step after the manufacturing process of the master shown in FIG.

FIG. 17 is a cross-sectional view showing a step after the manufacturing process of the master shown in FIG. 16;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate (light guide) 2 incident light 3 optical element (movable piece) 4 microprism 5 support structure layer 6 actuator 7 upper electrode and spring structure 8 lower electrode 9 anchor 10 optical switching element 11 post (post) 20 semiconductor substrate 25 Actuator array layer 26 Optical element array layer 32, 34 Sacrificial layer 35, 36 Resin 47 Gap for separation 50 Optical switching device 55 Image display device 60, 70 Transfer type (micro replica) 62, 72 Molding surface 64, 74 Projection 90 , 92 Transfer-type master

Claims (15)

[Claims] 1. A method for manufacturing a microstructure in which a plurality of movable pieces are arranged in an array on a substrate, comprising: applying a first resin to be the movable pieces on the substrate; Manufacturing a microstructure having a step of pressing at least one part of the movable piece by pressing a resin with a transfer mold having a plurality of separation protrusions forming a gap capable of separating the resin in units of the movable piece; Method. 2. The method according to claim 1, wherein the fine structure is an image display device, and the movable piece is manufactured in pixel units. 3. The microstructure according to claim 2, wherein the microstructure comprises an actuator array layer in which microactuators for driving the movable pieces are two-dimensionally arranged on the substrate, and in the forming step, A method for manufacturing a microstructure, comprising applying the first resin in a layer. 4. The method according to claim 3, wherein the movable piece is a micro-optical element capable of turning on / off incident light. 5. The movable piece according to claim 4, wherein the movable piece includes a V-shaped prism that changes the angle of the incident light and reflects the incident light.
A first step of forming a V-shaped groove by laminating the above resins, and a second step of forming a prism by applying a second resin to the V-shaped groove. A method for producing a featured microstructure. 6. The transfer die according to claim 5, wherein the transfer die used in the first step includes a plurality of inverted V-shaped molding projections that define the V-shaped groove. A method for manufacturing a microstructure, wherein the separation projection is formed at a valley portion of a molding projection. 7. The transfer die according to claim 5, wherein the transfer die used in the second step has a molding surface that defines an upper surface of the prism, and the separation projection is perpendicular to the molding surface. A method for manufacturing a microstructure, wherein 8. The method according to claim 5, wherein the first transfer mold used in the first step includes a plurality of inverted V-shaped molding projections defining the V-shaped groove, The separation projections are formed at the valleys of these molding projections, and the second transfer mold used in the second step has a molding surface that defines the upper surface of the prism, The separation protrusion is formed perpendicular to the molding surface, and the width of the separation protrusion of the first transfer mold is greater than the width of the separation protrusion of the second transfer mold. A method for producing a fine structure, characterized by having a small width. 9. The method according to claim 4, wherein the micro-actuator is an electrostatic actuator, and the micro-optical element is a micro-prism performing optical switching by evanescent light. 10. A transfer die for forming a plurality of movable microstructures on a substrate by applying a resin on a substrate and then applying a pressure on the substrate, wherein a plurality of gaps capable of separating the resin into movable units are formed. Transfer type with projections. 11. The transfer mold according to claim 6, wherein: 12. The transfer mold according to claim 7. 13. The first transfer type according to claim 8, wherein: 14. The second transfer mold according to claim 8, wherein: 15. A step of manufacturing, on a substrate, an actuator array layer in which micro-actuators are arranged in an array, and manufacturing an optical element array layer in which micro-optical elements are arranged in an array on the actuator array layer. In the step of manufacturing the optical element array layer, after a first resin is applied on the actuator array layer, a gap that can be separated into the micro optical element unit with respect to the first resin is provided. A transfer die provided with a plurality of separating projections forming a plurality of micro-optical elements arranged in a plane to form the optical element array layer, the image display device comprising: Manufacturing method.