JPH08304719A - Method for modifying surface of dmd - Google Patents

Abstract

PURPOSE: To provide a method for modifying the surface of a DMD which does not require an alignment stage and additional constitution to the DMD. CONSTITUTION: This method for selectively modifying the reflection surfaces of the respective micromirrors of the DMD comprises directing only the reflection surface of the specific micromirrors among the micromirrors A to C constituting the DMD to a prescribed direction and blowing a prescribed material to be deposited by evaporation to the substrate surface of the DMD from diagonally over the entire part thereof, thereby forming a vapor deposited film consisting of the material to be deposited by evaporation only on the reflection surface of the specific micromirror directed to the prescribed direction without depositing the materials to be deposited by evaporation on the reflection surfaces of the micromirrors exclusive of the specific micromirror.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying the surface of DMD, and more particularly to colorization of DMD.

[0002]

2. Description of the Related Art A DMD (Digital Micromirror Device or Deformable Micromirror Device) is a microdevice newly proposed in recent years. For example, Solid State Technology (Solid State Technolog
y), July 1994, pp. 63-68, SID 1993 digest version 1st.
012 to 1015, SPII
Critical Revise Series (SPIE Critical
Reviews Series) Vol. 1150, pp. 86-102
As disclosed in page etc., the DMD is composed of a large number of micro mirrors (reflection mirrors) arranged in a grid pattern.

As described above, the DMD is an integration of minute micromirrors, and the angle (that is, the direction) of the micromirrors is changed by the electrostatic attraction between the electrodes and the micromirrors provided for each micromirror. Change. That is, the direction of each micro mirror is configured to be individually drive-controlled. Incidentally, each micromirror has a square shape of, for example, about 20 μm × 20 μm, and one DMD is composed of, for example, hundreds of thousands to millions of micromirrors. Projection-type displays are particularly important for DMD applications.

By the way, in US Pat. No. 5,240,818 and US Pat. No. 5,168,406, three colors of cyan, magenta, and yellow are colored for each micromirror, and a desired color is formed on a screen by combining these three colors. How to get it is proposed. And U.S. Pat.
In JP-A-406, as a method for coloring (coloring) only a specific micromirror, a colored resist is applied on all the micromirrors that make up the DMD, and unnecessary micromirrors are formed by photolithography. The method of removing the resist is disclosed.

Further, US Pat. No. 5,240,818 discloses
As a method for colorizing a specific micromirror, a method is disclosed in which a sheet obtained by patterning a desired color pattern with a heat sublimation dye is aligned on a DMD to be sublimated. Further, a method has also been proposed in which a specific micromirror is charged and a dye gas charged with a polarity opposite to that of the potential is adsorbed. In this specification, forming a vapor-deposited film having a predetermined film thickness on the reflecting surface of each micromirror of the DMD for colorization or changing the reflectance is referred to as “surface modification”.

[0006]

The above-mentioned US Pat. No. 5,16
Since the surface modification method disclosed in Japanese Patent No. 8,406 uses photolithography, highly accurate alignment (alignment) between the DMD and the mask is required. Further, among the surface modification methods disclosed in the above-mentioned US Pat. No. 5,240,818, the method using a heat sublimable sheet requires highly accurate alignment between the sheet sublimated with the heat sublimable dye and the DMD.

Further, among the surface modification methods disclosed in the above-mentioned US Pat. No. 5,240,818, in the method of charging a specific micromirror, only the potential of the specific micromirror needs to be changed. However, in the DMD, usually, all micromirrors are connected to the same electric potential, and therefore, in order to change only the electric potential of a specific micromirror, the bias line of the micromirror is changed for each micromirror on which the same surface modification is performed. Special measures such as installation are required.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method of modifying the surface of a DMD which does not require an alignment step or an additional structure for the DMD.

[0009]

In order to solve the above problems, the present invention provides a method for selectively modifying the reflective surface of each micromirror of a DMD, the method comprising the steps of:
Among the micromirrors constituting the above, only the reflecting surface of a specific micromirror is directed in a predetermined direction, and a predetermined vapor deposition material is sprayed obliquely to the substrate surface of the DMD, and the micromirrors other than the specific micromirror are sprayed. The surface modification of DMD, characterized in that a vapor deposition film made of the vapor deposition material is formed only on the reflection surface of the specific micromirror facing the predetermined direction, without depositing the vapor deposition material on the reflection surface of the mirror. Provide a way.

According to a preferred embodiment of the present invention, the DM
A vapor-deposited film having a predetermined film thickness is formed on the reflecting surface of each micromirror D, and the reflecting surface of each micromirror is colored according to the film thickness. Alternatively, the predetermined vapor deposition material is a black pigment, and a vapor deposition film having a predetermined thickness is formed on the reflecting surface of each micromirror of the DMD, and the reflectance of each micromirror is adjusted according to the thickness. It is preferable to change.

[0011]

FIG. 1 is a conceptual diagram for explaining the operation of the DMD surface modification method according to the present invention. In FIG.
(A) shows a state in which a vapor deposition film is formed on the reflection surface of each micromirror of the DMD, and (b) shows a state in which no vapor deposition film is formed on the reflection surface of each micromirror of the DMD.

In FIG. 1, three adjacent micromirrors 11 and 1 out of many micromirrors constituting the DMD.
Only 2 and 13 are shown. The surface on the right side of each of the micromirrors 11, 12 and 13 is a reflecting surface. And each micromirror 11, 12 and 13
Are controlled independently of each other between an ON state in which the reflective surface has the orientation shown in FIG. 1A and an OFF state in which the reflective surface has the orientation shown in FIG. 1B.

In the present invention, as shown by an arrow in the figure, a predetermined vapor deposition material supplied from a supply source (not shown) is DM
Spray diagonally on D. This is a vapor deposition method generally called oblique vapor deposition. In the oblique vapor deposition method, the vapor deposition material does not deposit on the surface shielded against the flight direction of the vapor deposition material, but the vapor deposition material deposits only on the surface facing the flight direction of the vapor deposition material.

That is, in the state shown in FIG. 1A, all the reflecting surfaces of each of the micromirrors 11, 12 and 13 are opposed to the flying direction of the vapor deposition material. Therefore, the vapor deposition material reaches all the reflection surfaces of each micro mirror 11, 12 and 13, and the vapor deposition film is formed on each reflection surface. On the other hand, in the state shown in FIG. 1B, all the reflecting surfaces of each of the micro mirrors 11, 12 and 13 are shielded against the flying direction of the vapor deposition material. Therefore, the vapor deposition material does not reach all the reflecting surfaces of each micro mirror 11, 12 and 13, and the vapor deposition film is not formed on each reflecting surface.

As described above, according to the present invention, only the reflecting surface of a specific micromirror among the micromirrors constituting the DMD is directed in a predetermined direction. Then, a predetermined vapor deposition material may be sprayed obliquely on the substrate surface of the DMD (shown by the broken line in FIG. 1) to form a vapor deposition film only on the reflecting surface of a specific micromirror that faces in a predetermined direction. it can.
That is, according to the present invention, the alignment step and D
The reflective surface of any micromirror can be surface-modified without requiring an additional configuration for the MD.

When a vapor-deposited thin film is formed on the reflecting surface (mirror surface) of the micromirror, the light of a specific wavelength is absorbed by the interference between the light reflected on the mirror surface and the light reflected on the surface of the thin film, depending on the film thickness. It is known to exhibit interference colors. At this time, the relationship between the absorption maximum wavelength λ and the film thickness d is expressed by the following equation (1).
It is represented by. nd = λ (2m + 1) / 4 (m = 0,1,2, ...) (1) where n is the refractive index of the vapor deposition film

In this way, it is possible to obtain a micromirror having a different absorption maximum wavelength depending on the film thickness of the vapor deposition film formed on the micromirror. Also, according to the present invention D
In the MD surface modification method, it is possible to form a vapor deposition film having a desired film thickness on an arbitrary micromirror by controlling the vapor deposition time, for example. Therefore, for example, in order to obtain three types of absorption maximum wavelengths of 440 nm, 550 nm, and 620 nm, vapor deposition films having three types of film thicknesses are formed on the micromirrors A, B, and C, respectively, to colorize the DMD. You can

FIG. 2 is a diagram showing the arrangement of the respective micromirrors in the color DMD. In the DMD of FIG. 2, three types of micromirrors A having different absorption maximum wavelengths,
B and C are arranged in the horizontal direction in the figure to form one micromirror group. Each micromirror group corresponds to each pixel of the image formed on the screen. In addition,
Although only six micromirror groups are shown in FIG. 2 due to the limitation of space, in reality, a large number of micromirror groups are vertically and horizontally arranged on the DMD.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 3 is a flowchart showing steps of a method for modifying the surface of DMD according to an embodiment of the present invention. FIG. 4 is a diagram showing a state of oblique vapor deposition according to each step of the flowchart of FIG. In addition, in FIG.
Only three adjacent micromirrors A, B and C among the micromirrors constituting D are shown.

In this embodiment, each micromirror constituting the DMD is surface-modified with a silicon dioxide (SiO ₂ ) thin film having three kinds of film thickness to produce a colored DMD.
When the refractive index n of the silicon dioxide thin film is n = 1.46, the absorption maximum wavelengths of the micromirrors formed with the silicon dioxide thin films having the film thicknesses of 380 nm, 470 nm and 530 nm are 440 nm and 550 n, respectively.
m and 620 nm. In this embodiment, a silicon dioxide thin film having a film thickness of 380 nm is formed on the micromirror A.
By forming a silicon dioxide thin film having a thickness of 470 nm on the micro mirror B and a silicon dioxide thin film having a thickness of 530 nm on the micro mirror C, DM
Color D.

As shown in FIG. 3, when the production of the color DMD (step 31) is started, the DMD produced by the usual process is first placed at a predetermined position in the vapor deposition apparatus for performing oblique vapor deposition (step 32). ). Then, FIG.
As shown in (a), all the micromirrors A, B and C are turned on (step 33). As shown in the drawing, in the ON state, each micromirror is tilted clockwise by 10 ° with respect to the substrate surface of the DMD (shown by a broken line in the drawing). By the way, in the OFF state, as shown for the micro mirror A in FIG.
It is tilted counterclockwise by 10 ° with respect to the substrate surface of D.

In this way, the oblique vapor deposition is started with all the micromirrors A, B and C kept in the ON state (step 34). In the oblique vapor deposition, as shown by the arrow in the figure, silicon dioxide, which is a vapor deposition material, is sprayed from an oblique direction inclined by 9 ° with respect to the substrate surface of the DMD. In this state, the reflecting surfaces (the surfaces on the right side in the figure) of the micromirrors A, B and C are opposed to the flying direction of silicon dioxide.
Therefore, a silicon dioxide thin film is formed on the reflecting surfaces of the micromirrors A, B and C. The oblique vapor deposition operation is carried out when the film thickness of the silicon dioxide thin film formed on each micromirror is 3
It continues until it becomes 80 nm.

When the thickness of the thin film formed on each micromirror reaches 380 nm, only the micromirror A is turned off (step 35). And FIG.
As shown in (b), the oblique deposition is continued with the micromirror A turned off and the micromirrors B and C turned on. In this state, the reflecting surface of the micro mirror A is shielded against the incoming direction of silicon dioxide, and the reflecting surfaces of the micro mirrors B and C are opposed to the incoming direction of silicon dioxide. Therefore, the silicon dioxide thin film is not formed on the reflecting surface of the micro mirror A, but the silicon dioxide thin film is formed only on the reflecting surfaces of the micro mirrors B and C. The oblique deposition operation is continued until the film thickness of the silicon dioxide thin film formed on the micro mirrors B and C reaches 470 nm.

When the thickness of the silicon dioxide thin film formed on the micro mirrors B and C reaches 470 nm, the micro mirror B is also turned off (step 36).
Then, as shown in FIG. 4C, the oblique deposition is continued with the micromirrors A and B in the OFF state and only the micromirror C in the ON state. In this state, the reflecting surfaces of the micromirrors A and B are shielded against the flying direction of silicon dioxide, and only the reflecting surface of the micromirror C faces the flying direction of silicon dioxide. Therefore, the silicon dioxide thin film is not formed on the reflecting surfaces of the micromirrors A and B, but the silicon dioxide thin film is formed only on the reflecting surface of the micromirror C. The oblique deposition operation is
This is continued until the film thickness of the silicon dioxide thin film formed on the micro mirror C reaches 530 nm.

In this way, the micromirror A has 380n.
m, micromirror B to 470 nm, micromirror C
The process of forming the respective silicon dioxide thin films having a film thickness of 530 nm is completed (step 37). as a result,
The absorption maximum wavelength of the micro mirror A is 440 nm, the absorption maximum wavelength of the micro mirror B is 550 nm, and the absorption maximum wavelength of the micro mirror C is 620 nm. Thus, D
Coloring of MD, that is, surface modification can be performed.

In this embodiment, the size of one side of each micromirror is about 15 μm, and the distance L between the centers thereof is about 23.
μm. Therefore, for example, as shown in FIG. 4A, the micromirror B (or A) to be vapor-deposited is not shielded by the adjacent micromirror C (or B). However, when the center-to-center distance of each micromirror is small, the micromirror to be deposited may be blocked by the adjacent micromirrors. FIG. 5 is a diagram illustrating an oblique vapor deposition operation in the case where the center-to-center distance of each micromirror is small and the micromirror to be vapor-deposited is shielded by the adjacent micromirrors. In FIG. 5, only five adjacent micromirrors A to E are shown.

As shown in FIG. 5A, when the center-to-center distance of each micromirror is small, the micromirror A,
Only C and E are turned on. Then, a silicon dioxide thin film having a predetermined thickness is formed only on the micromirrors A, C and E. Then the micromirrors A, C and E are turned to O
At the same time as the FF state, the micromirrors B and D are turned on. Then, a silicon dioxide thin film having a predetermined thickness is formed only on the micromirrors B and D.

As described above, when the center-to-center distance of each micromirror is small, it is preferable to perform oblique vapor deposition without simultaneously turning on two adjacent micromirrors. That is, for example, the first step of forming only a desired micromirror among the even-numbered micromirrors in the ON state to form a silicon dioxide thin film having a predetermined thickness, and the desired micromirror among the odd-numbered micromirrors in the ON state. In combination with the second step of forming a silicon dioxide thin film having a predetermined thickness, a silicon dioxide thin film having a desired thickness can be selectively formed on each micromirror.

Generally, in the case of surface modification for the purpose of colorization, two adjacent micromirrors are often subjected to different surface modification (coloring). Therefore, for example, in the case of the present embodiment, with only the micromirror A in the ON state, oblique vapor deposition is performed to a film thickness of 380 nm,
Next, only the micromirror B is turned on and the film thickness 470 is set.
It is also possible to perform oblique vapor deposition up to nm, and finally, only the micromirror C is turned on to perform oblique vapor deposition up to a film thickness of 530 nm.

In the above-mentioned embodiment, an example in which silicon dioxide is used as a vapor deposition material to color the DMD is shown, but it is clear that the DMD can be colorized using other suitable vapor deposition material. Is. Further, in the above-mentioned embodiment, the example in which the DMD is colored is shown, but the present invention can be applied to the surface modification in which the reflectance of each micromirror is changed by using the black pigment as the vapor deposition material. .

[0031]

As described above, according to the present invention, the DMD
It is possible to form a thin film only on the reflecting surface of the specific micromirror by oblique vapor deposition by directing the reflecting surface of the specific micromirror of the micromirrors constituting the above in a predetermined direction. That is, according to the present invention, an alignment step and an additional configuration for the DMD are not required,
The reflective surface of any micromirror can be surface-modified.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating the operation of the method for modifying the surface of DMD according to the present invention.

FIG. 2 is a diagram showing an arrangement of micromirrors in a color DMD.

FIG. 3 is a flowchart showing steps of a method for modifying a surface of DMD according to an embodiment of the present invention.

FIG. 4 is a diagram showing a state of oblique vapor deposition according to each step of the flowchart of FIG.

FIG. 5 is a diagram illustrating an oblique vapor deposition operation in the case where the center-to-center distance of each micromirror is small and the micromirror to be vapor-deposited is shielded by the adjacent micromirrors.

[Explanation of symbols]

 11-13 Micromirror AE Micromirror 31-37 Each step of surface modification method

Claims (3)

[Claims] 1. A method for selectively modifying the reflective surface of each micromirror of a DMD, wherein only the reflective surface of a specific micromirror among the micromirrors constituting the DMD is directed in a predetermined direction. The specific micro-mirror directed in the predetermined direction is sprayed with a predetermined vapor deposition material obliquely with respect to the substrate surface, without depositing the vapor deposition material on the reflecting surface of the micro-mirror other than the specific micro-mirror. A method for modifying the surface of DMD, comprising forming a vapor deposition film comprising the vapor deposition material only on the reflective surface of. 2. The reflective surface of each micromirror of the DMD is formed with a vapor deposition film having a predetermined film thickness, and the reflective surface of each micromirror is colored according to the film thickness. The method for modifying the surface of DMD according to claim 1. 3. The predetermined deposition material is a black pigment,
The vapor deposition film having a predetermined film thickness is formed on the reflecting surface of each micro mirror of the DMD, and the reflectance of each micro mirror is changed according to the film thickness. DMD surface modification method.