JPS59139002A - Process for preparing original plate for microprism - Google Patents

Abstract

PURPOSE:To obtain a microprism having a sufficiently small inclination by forming a multilayer film consisting of >= two layers having each an etching rate higher than each succeeding lower layer, on a substrate to form pyramidal projections and recessions by etching. CONSTITUTION:An SiO2 film 2 is formed on an Si substrate 1 by the CVD process, the film is heat-treated for a specified time, then a second SiO2 film 3 to be etched is formed by the CVD process on the film 2 and heat-treated. Similarly, a third and a fourth SiO2 films 4, 5 are formed successively thereon by the CVD process and heat-treated. The heat treatment is performed in such a manner that each SiO2 film 2-5 exhibits different etchability for an HF etching liquid, namely, that each lower layer film exhibits smaller etchability than each adjacent upper layer film. Then, a photoresist film as a masking layer 6 is deposited on the film 5; plural square windows 7 arranging longitudinally and laterally are formed thereon by the exposure and development. Finally, recessions 8 are formed by etching.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used for a focusing plate for distance measurement of an optical finder of a so-called single-lens reflex camera or a video camera, or a micro condenser lens arranged on a solid-state image pickup body. The present invention relates to a method for manufacturing a microprism original plate for obtaining a microprism.

BACKGROUND TECHNOLOGY AND PROBLEMS The use of microprism focus plates for distance measurement in optical viewfinders of single-lens reflex cameras and video cameras has been considered. This reticle is made up of a large number of square pyramids, for example, which serve as microprism bodies with a constant inclination angle. With this configuration, the light beam can be effectively used without focusing using an aerial image. This has the advantage of high distance measurement accuracy without darkening the field of view.

In addition, in a solid-state imaging device, a microlens is formed on the solid-state imaging plate corresponding to each pixel, and by focusing light, the effective aperture ratio is increased and sensitivity is improved. It is considered.

Such microprisms used as focusing plates or condensing lenses each require a three-dimensional highly accurate fine pattern processing technique for the prism element.

Normally, to obtain this kind of microprism, a mold is formed by machining, which has irregularities corresponding to the irregularities of the final microprism, that is, each microprism element, and a plastic plate is pressed using this mold. The method used is to obtain it by doing so. However, in this mold, it is usually not possible to form the pitch of the concavities and convexities that form the prism body to be sufficiently small, and the inclination angle, for example, the base angle (inclination angle with respect to the base) of the conical concavities and convexities, cannot be formed sufficiently small.
θ is 15° to 200°, and the base angle θ is around 7°, which is a small angle required for the above-mentioned focusing plate or microprism as a condensing prism, and the pitch is also insufficient. The disadvantage is that small items cannot be obtained.

Purpose of the Invention In the present invention, a sufficiently small inclination angle, that is, a base angle θ, for example, around 7° or less, for example 6
The object of the present invention is to provide a method for manufacturing a microprism original plate that can obtain microprisms having an angle of .degree.

Summary of the Invention The present invention forms a multilayer α film of two or more layers on a substrate such as Ni or quartz. These films, namely the upper layer film and the lower layer film, are
The prism of the υ microprism is composed of films whose etching properties are different, for example, the etching rate of the upper layer film with the same etching solution is similar to that of the lower layer film, and an etching resist is further applied on the upper layer film. An etching mask having windows formed with a pitch corresponding to the element body is deposited, and the above-mentioned upper and lower layers are etched through the windows of this etching mask, and the etching difference between the two forms a pyramidal shape, for example, a truncated square. A rectangular pyramid-shaped concave portion is formed, and by aggregating these concave portions, a microprism original plate having conical concavities and convexities formed on one surface as a whole is obtained.

In order to produce a microprism using the microphone o 7' rhythm original plate thus obtained, first, for example, relatively thick metal plating such as Ni1 or Cr is applied to the microprism original plate. For this metal plating such as Ni or Cr, for example, electroless plating is performed and then electroplating is applied to the desired thickness, or Cu, etc. is vapor deposited on the original plate and the surface is made conductive. After that, a metal plating layer of Ni or Cr or the like is formed to a desired thickness by electroplating. In this case, the thickness of the plating layer is sufficiently large, for example, about 15 m+, although the depth of the irregularities on the original plate is small, for example, about 1 μm. In addition, prior to Ni or Cr plating, for example, a mold release treatment is applied to the surface of the Cu vapor deposited film of this base layer, whereby this N1 or Cr plated layer is peeled off from the original plate and the original plate is removed. A metal master having an uneven surface to which the unevenness is transferred is obtained. Furthermore, this metal master was subjected to a similar peeling treatment, and Ni,
By plating metal such as Cr and peeling it off, a template with the same unevenness and lean as the original plate is obtained, and this template is used to mold, for example, a plastic plate such as acrylic resin in a softened state, or molding. A microprism is obtained by doing this.

EXAMPLE Next, an example of the present invention will be explained in detail with reference to FIGS. 1 to 4. First, as shown in FIG. 1, for example, an St substrate (1) is provided, and a first 8102 film (2) to be etched is deposited on this by chemical vapor deposition (CVD) using 5IO2 as a deposit. Form. Then, heat treatment is performed on this for a predetermined time t1. And this first 8
A second SlO□ film (3) to be etched is similarly deposited on the 102 film (2) by the CVD method, and is subjected to heat treatment for a predetermined time t2. In this way, the third and fourth 5xO2 films to be etched (
4) and (5) are sequentially deposited by CVD, and each film is subjected to heat treatment for predetermined times t3 and t4, respectively.

In this case, the heat treatment conditions after deposition of each of the first to fourth layers (2) to (5), such as the heat treatment time t1 to t4, or the heating temperature, can be changed to form the respective layers (2) to (5).
5) shows different etching properties with respect to etching solutions such as hydrogen fluoride-based etching solutions.
Specifically, the etching rate of the lower layer film is made lower than that of the upper layer film. That is, for example, the heat treatment temperature for each layer is selected to be as high as the heat treatment temperature for the lower layer, for example, 1000°C for the bottom layer (2) and 700°C for the top layer (5). Each intermediate layer (
3) and (4) are selected so that the temperature gradually decreases toward the upper layer.

Next, as shown in FIG. 2, a mask layer (6), such as a photoresist film, which becomes an etching resist is deposited on the uppermost film (5), and the mask layer (6), for example, a photoresist film, is applied to the uppermost film (5), and is exposed and developed to create the required spacing. For example, a plurality of square windows (7) having a width of
erect and drill holes horizontally.

Next, as shown in FIG. 3, each layer (5) (
4) (3) Perform etching on (2) to form a recess (8). In this case, the recess (8) can be formed by etching, for example, using a hydrogen fluoride etching solution containing ammonium fluoride and hydrofluoric acid at a ratio of 100:12 (4 parts of heavy A). In this way, since the etching speed of the upper layer film is fast, the progress of etching in the lateral direction (plane direction) is also reduced. However, in this case, the etching stops when the etchings from each layer (7) collide under the center of the adjacent windows (7). (8) is completely laid and formed. In other words, for example, if the shape (7) is selected to be a quadrangle such as a square, a quadrangular pyramid-shaped recess (8) should be formed across the thickness direction of each layer (5), (4), (3), and (2). I can do it.

After that, as shown in FIG. 4, an etching resist film (6
), a microprism original plate (9) having the desired cone-shaped irregularities formed on its surface can be obtained.

In addition, in the above-mentioned example, the first to fourth films (2) to (
5) are each formed by a S102 film by CVD method, but for example, phosphor silicate glass or boron silicate glass in which phosphorus P and boron B are doped in this 5i02 film can also be used.
Each layer (2) ~ not only by VD method but also by vapor deposition, sputtering, etc.
(5) can also be formed, and these films (2) can also be formed.
~(5), for example, 513N by plasma CVD method
It can also be formed by four films. In this case, the etching for forming the recesses (8) is not limited to so-called wet etching using an etching solution, but a plasma etching method or the like may also be applied.

In addition, in the above example, the film forming the recessed portion by etching has a four-layer structure of the first to fourth films (2) to (5), but it is also possible to use two or more layers, or any layer as necessary. It can be a number. In addition, in the above example, the first to
This is a case where the heat treatment conditions are changed to create a difference in etching rate for the fourth layers (2) to (5). It is also possible to adopt a configuration in which the etching rate is changed by changing the concentration in the thickness direction.

The present invention will be described in detail with reference to FIGS. 5 and 6.

In this example, as shown in FIG.
1), and by thermally oxidizing the surface thereof, for example, a first etching target 5tO having a thickness of 5750× is formed.
2 film (6) is formed, and on top of this, this SiO2 film (6) is formed.
) A second silicate glass layer α3 to be etched is doped to a thickness of 1000× with a film P whose etching speed is faster than that of the etching solution used for etching. Formed by CVD method. Then, a mask layer (6) such as a photoresist which becomes an etching resist is deposited on this. In this case, the film α of the photoresist (6) is formed.
For example, a 5102 film α, which has excellent adhesion with photoresist because of its low adhesion strength against ), exposed and developed to form a large number of windows (7) with the required shape and size at 8 intervals, and then the film αQ-α→ - (Etching for L-build.

In this way, as described above, since the etching speed of the upper layer film (α) is faster than that of the lower layer film (12), the concave portion (8) that spreads upward is formed as shown by the chain line in FIG. In this case as well, each layer (etching from the force collides υ
If the etching is stopped at the point where they are aligned, the cone-shaped recess (8) will be completely formed. Thereafter, by washing with water, the photoresist film (6) lifted up by etching is removed, resulting in a prism original plate (9) with cone-shaped irregularities formed on its surface, as shown in Figure 6. . Incidentally, the inclination angle θ of the recessed portion (8) thus obtained is 5.
It was 9°.

Note that in the examples explained in FIGS. 1 to 4, the fifth
Also in the example explained in Fig. 6 and Fig. 6, the recess (8)
When selecting the thickness of each film to be etched so that it exists in the film (2) or the film to be etched above the surface of the substrate (1), the bottom (apex angle) of ◇ Effects of the Invention As mentioned above, in the present invention, two different types of etching properties are used.
Since cone-shaped unevenness is formed by etching by forming more than one layer on a substrate, a conical cone having a desired inclination angle θ can be arbitrarily selected by appropriately selecting a change in etching speed. If it's possible,
In reality, as mentioned above, this θ is around 7° or less, which is 5.9
It was possible to form the angle at a small angle of °.

In this way, in the present invention, it is possible to easily form the unevenness having the required angle of inclination, so this original plate (9)
This makes it suitable for use in obtaining a microprism for a condensing lens system in a solid-state image pickup body or a focus plate for an optical finder as described above.

[Brief explanation of drawings]

FIGS. 1 to 4 are enlarged sectional views of each step in one example of the method for manufacturing a microprism original plate according to the present invention, and FIGS. 5 and 6 are enlarged sectional views of each step in other examples. It is. (9) is the original plate according to the present invention, (1) is its substrate, (2)
~(5). (To) (B) is a film to be etched, (6) is a mask layer as an etching resist, (7) is an etching window thereof, and (8) is a recessed portion due to etching. Figure 1 Figure 1 Figure 5 Figure 6 Procedural amendment March 24, 1980 Kazuo Wakasugi, Commissioner of the Patent Office (Chief Judge of the Patent Office) 1. Indication of the case Patent Application No. 14181 of 1988 Bishi fourri
N Shigenban Seizoku Hoku Hoku 2 Invention name 'rfr Manufacturing method of micro prism element original plate 3, relationship with the case of the person making the amendment Patent applicant address 6-7-35, Kitashina, Tokyo Parts Ward Name (21
8) Sony Corporation Representative Director Norio Ohga 4, Agent 1-8-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo (
Shinjuku Building) 6. The number of inventions will increase due to correction, lie! -,,,\ (2) Amend the claims in the specification as in the attached sheet. (3) Same, page 1, lines 14-15, ``Relates to use...'' to ``Relates to the method of manufacturing a micro-optical original plate for obtaining micro-optical elements such as micro-lenses and micro-prisms to be used.'' I am corrected. (4) Same, page 2, line 14, ``this species'' is corrected to ``this species.'' (5) Same, page 3, line 6, ``Unobtainable'' is corrected to ``Hard to obtain.'' (6) Same page, lines 11-12 have F6°...
``Manufacturing method'' has been corrected to ``A manufacturing method for a microscopic optical element original plate that can obtain a microscopic optical element (microprism, microlens, etc.) having an angle of 6°.'' (7) Same, page 12, line 1, "micro prism" is corrected to "micro optical element." (8) Same, same page, lines 4-5 “for microprism” changed to “
"Micro optical element" is corrected. The above claims are characterized in that a multilayer film of two or more layers is formed on a substrate, the etching speed of the upper layer film being higher than the etching speed of the lower layer film, and etching is performed to form cone-shaped irregularities. A method for manufacturing a micro prism element original plate.

Claims (1)

[Claims] A master plate for a microprism, characterized in that a multilayer film of two or more layers is formed on a substrate, and the etching speed of the upper layer film is higher than that of the lower layer film, and etching is performed to form cone-shaped irregularities. Production method.