JPS60246634A - Manufacture of elastic surface wave device - Google Patents

Abstract

PURPOSE:To realize the production of high-precision interdigital electrodes by a method wherein the width of a pattern corresponding to equi-distantly arranged interdigital electrodes is caused to be smaller than the distance between the interdigital electrodes. CONSTITUTION:The device of this design is constituted of a piezoelectric substance 1, electrode forming members, resist 3, glass mask 4 and a pattern 8, and the pattern 8 is formed to be smaller in width than the distance between interdigital electrodes. That is, on the glass mask 4, the distance B between interdigital electrodes is formed to be larger than the width A' of the pattern 8. It follows therefore that, when the pattern 8 wherewith the resist 3 is in close contact is exposed to rays 6 projected by a UV illuminator, the quantity of diffracted rays 61 is far smaller than the quantity of rays 6 directly hitting the resist 3 without being diffracted. The resist 3 therefore is exposed to the rays 6 as hatched in the figure (c). The entirety of the resist 3, except the portion corresponding to the pattern 8 and the interdigital electrodes 7, is exposed to the UV energy. A combination of the exposed resist 3 and the piezoelectric substrate 1 is subjected to development and etching, for the formation of the interdigital electrodes 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a surface acoustic wave device, and more particularly to a method of manufacturing a surface acoustic wave device in which equally spaced intersecting finger electrodes are formed with high precision.

(a) Industrial application field Surface acoustic wave elements used in surface acoustic wave devices consist of a substrate that propagates surface acoustic waves and a transducer that converts energy between electricity and acoustic waves, and drives surface acoustic waves. There are various methods for detection, but currently the most commonly used method is to form interdigitated interdigitated electrodes on a piezoelectric substrate, but the quality of the surface acoustic wave device's characteristics depends on the interdigitated electrode It depends on how accurately it is formed.

Formation on this piezoelectric substrate is carried out by photoetching using a glass mask corresponding to the interdigitated finger electrodes, but when the interdigital electrode width is less than 1 μm, the pattern is formed by light diffraction and interference. Since it is difficult to form interdigitated electrodes that match the above, there is a strong demand for an improved manufacturing method that allows the interdigitated electrodes to be formed easily and accurately.

(bl) Conventional technology Figure 2 is for explaining the conventional manufacturing method of a surface acoustic wave device, (8) is a side view of a glass mask, (b) is a side view showing the photosensitive distribution of resist, (C) is a side view after development and etching.

An electrode member 2 made of a metal such as aluminum is deposited on a piezoelectric substrate 1 made of, for example, crystal, and a resist 3 that is sensitive to light is applied onto the electrode member 2. The glass mask 4 has equally spaced (
A) pattern 5 is formed. Then, with the pattern 5 side of the glass mask 4 in close contact with the resist 3 as shown in FIG. It is thought that all of the patterns except the pattern 5 corresponding to the finger electrodes 7 are exposed to light, and when the piezoelectric substrate 1 integrated with the exposed resist 3 is developed and etched, the intersecting finger electrodes 7 corresponding to the patterns 5 are formed. It is being However, due to the gap between the resist 3 and the glass mask 4, the light ray 6 is diffracted and becomes a curved light ray 61, which exposes the resist 3 corresponding to the pattern 5 that should not be exposed, resulting in accurate intersection as shown in Fig. 2 (cl). There was a problem in that it was very difficult to form the finger electrodes 7.

(cl Problems to be Solved by the Invention) In order to solve the above-mentioned conventional problems, the present invention forms the width of the pattern corresponding to the equally spaced intersecting finger electrodes to be narrower than the interval between the intersecting finger electrodes. It is an object of the present invention to provide a novel method for manufacturing a surface acoustic wave device, which makes it possible to easily manufacture interdigitated electrodes with good accuracy while taking into account the effects of diffraction, interference, etc.

fdl Means for Solving Problems The purpose is to provide a method for manufacturing a surface acoustic wave device in which equally spaced comb-shaped interdigitated electrodes are formed on a substrate by photoetching, and to form the equally spaced interdigitated finger electrodes. This is achieved by forming an electrode finger pattern on a glass mask that does not transmit light and is smaller than the spacing between the electrode fingers.

In other words, in the present invention, the width of a pattern formed on a conventional glass mask is made smaller than the electrode finger spacing, thereby producing evenly spaced interdigitated finger electrodes.

ff) Examples Examples of the method for manufacturing a surface acoustic wave device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining an embodiment of the method for manufacturing a surface acoustic wave device according to the present invention (81 is a side view of a glass mask;
(b) is a side view showing the photosensitive distribution of the resist.

(C) is a side view after development and etching. In FIG. 1, the method for manufacturing a surface acoustic wave device of the present invention is composed of a piezoelectric substrate, an electrode member, a resist glass mask, a pattern, etc., as in FIG. 2, but is characterized in that the pattern is improved. . Therefore, parts other than the pattern are given the same reference numerals as in FIG. 2, and explanations of these parts will be omitted here. Pattern 8, which characterizes the present invention, has a width smaller than that of the interdigital electrodes.

In other words, the interval between the interdigital electrodes (B
) is formed in a large size on the glass mask 4.

Thus, when the pattern 8 side of the glass mask 4 is brought into close contact with the resist 3 as shown in FIG. The curved light ray 61, which is a part of the light ray 6, is very weak compared to the light ray 6 that reaches the resist 3, and the resist 3 is exposed to light as indicated by diagonal lines. is exposed to light,
The piezoelectric substrate integrated with the exposed resist 3 is developed.

When etching is performed, interdigitated electrodes 7 as shown in FIG. 1 (cl) are formed.

(3) Effects of the invention As is clear from the above explanation, according to the method for manufacturing a surface acoustic wave device according to the present invention, cross-finger electrodes with good accuracy can be easily manufactured by taking into consideration the effects of light diffraction, interference, etc. This greatly contributes to improving the quality of surface acoustic wave devices.

[Brief Description of the Drawings] Fig. 1 shows a method for manufacturing a surface acoustic wave device according to the present invention.
For explaining the examples, fal is a side view of a glass mask, (b) is a side view of the photosensitive phenomenon, (C) is a side view after development and etching, and Figure 2 is a conventional method for manufacturing a surface acoustic wave device. For explaining, +a) is a side view of the glass mask, (b) is a side view showing the photosensitive distribution of the resist, and (C) is a side view after development and etching. In the figure, 1 is a piezoelectric substrate, 2 is an electrode member, 3 is a l/cyst, 4 is a glass mask, 5.8 is a pattern, 6 is a light beam, 7 is a crossed finger electrode, and 61 is a curved light line. Figure 1 (Q) ・Figure 2 (Q)

Claims (1)

[Claims] A method for manufacturing a surface acoustic wave device in which equally spaced comb-shaped interdigitated finger electrodes are formed on a substrate by photoetching is provided. 1. A method of manufacturing a surface acoustic wave device, characterized in that an electrode finger pattern is formed through which light does not pass through.