JP2980427B2 - Manufacturing method of surface acoustic wave device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a surface acoustic wave device.
About the method .

[0002]

2. Description of the Related Art In the manufacture of electronic components such as semiconductor integrated circuits and surface acoustic wave filters which have become indispensable in electronic circuits in recent years, light-shielding patterns corresponding to wiring patterns of electronic components are formed in advance. A process of transferring a wiring pattern or the like from a glass mask to a substrate material of an electronic component by light exposure is used. In particular, recent large-capacity semiconductor memories require sub-micron wiring, and a light exposure method using a phase shift method has been proposed as one method for achieving this with good reproducibility.

Hereinafter, a light exposure method using this phase shift method will be described with reference to FIG.

FIGS. 2A to 2C show a conventional light exposure method which does not use the phase shift method. FIG. 2A is a cross-sectional view of a conventional glass mask used for transferring a wiring pattern onto a substrate material of an electronic component by performing light exposure. A conventional glass mask includes a glass substrate 1 and a light-shielding pattern 2 formed of a thin film of a metal such as chromium (Cr) and an oxide film thereof.

The light that has passed through the glass mask shown in FIG. 2A is focused on the substrate material of the electronic component to be focused, as shown in FIG.
Is shown. FIG. 2 (b) and FIG.
The horizontal axis of (c) corresponds to the horizontal position in the glass mask of FIG.

FIG. 2 (c) shows the light intensity distribution, which is almost the same as that shown in FIG. 2 (b). When the wiring pattern is a submicron pattern, the distribution shown in FIG.
Since the light reaches the portion where the light intensity should be zero by the light shielding pattern 2 in FIG.
It does not become 0. Therefore, the contrast of the light pattern transferred onto the substrate of the electronic component does not increase.

On the other hand, FIGS. 2D to 2F show a light exposure method using a phase shift method for improving contrast. FIG. 2D is a cross-sectional view of a glass mask using the phase shift method. The glass mask is a glass substrate 1, a light-shielding pattern 2 formed of a metal such as chromium (Cr) and a thin film of an oxide film thereof, and a shifter 3. It is composed of The shifter 3 is formed of a light transmissive thin film such as SiO _2, and is provided at every other light transmitting portion between the light shielding patterns 2.

The amplitude of light passing through the glass mask shown in FIG. 2D and focusing on the substrate material of the electronic component has a distribution shown in FIG. 2E. The wavelength of light used for light exposure is λ, and the refractive index of the light transmitting material used for the shifter 3 is n.
, The thickness d of the shifter 3 is λ / {2 (n−1)}.
The phase of light passing through the glass mask differs by 180 ° between passing through a portion with a shifter and passing through a portion without a shifter. For this reason,
Even in the case where light is diffracted, the amplitude of light in a region corresponding to a portion having a light-shielding pattern crosses 0, and as a result, FIG.
As shown in (f), the light intensity becomes 0 and the contrast of the light pattern transferred onto the substrate of the electronic component increases.

[0009]

However, if the conventional phase shift method is used for light exposure of a surface acoustic wave device having a comb-shaped electrode pattern, the following problems occur.

FIG. 3A shows a glass mask when performing light exposure of a surface acoustic wave device using a conventional phase shift method.

The shifter 3 is arranged so as to overlap the intersecting comb-shaped light-shielding patterns 4 and 5 with respect to the intersecting comb-shaped light-shielding patterns 4 and 5.

When light exposure is performed on a substrate of an electronic component using a glass mask as shown in FIG. 3A, the intensity pattern distribution of light focused on the substrate is as shown in FIG. 3B. . In FIG. 3B, a hatched portion corresponds to a portion not exposed to light. In this case, the comb-shaped light shielding pattern 4
Area 6 which bridges and shorts the pattern corresponding to 5 and 5
Can be done. The reason will be described with reference to FIG.

FIG. 4A is a sectional view corresponding to AA or BB of the glass mask shown in FIG. 3A. FIG. 4A is a sectional view of the glass substrate 1 of the glass mask and the shifter 3 formed of a SiO ₂ thin film or the like. Become. The film thickness of the shifter 3 is such that the wavelength of light used for light exposure is λ, and the refractive index of the material used for the shifter 3 is n.
Then, it is normal to set λ / {2 (n−1)}.

Therefore, the amplitude of the light passing through the glass mask and focusing on the substrate material of the electronic component is shown in FIG.
The phase of light is rotated exactly 180 ° between the region with the shifter and the region without the shifter. Therefore, a portion where the amplitude of light becomes 0 occurs at the boundary portion 7 between the region with the shifter and the region without the shifter, and the distribution of the light intensity is as shown in FIG.

In this boundary portion 7, since the resist film applied on the substrate material of the electronic component is not exposed,
In the boundary portion between the region with the shifter and the region without the shifter in the glass mask (b), the short-circuit region 6 remains even after the development,
There will be a short-circuit region between the comb-shaped light-shielding patterns 4 and 5. This is an obstacle in manufacturing the surface acoustic wave device using the phase shift method. Therefore, it is difficult to use the phase shift method for a glass mask for manufacturing a surface acoustic wave device having a comb-shaped electrode, and it is not possible to form a finer comb-shaped electrode. Could not be manufactured.

The present invention is applicable to a comb-shaped electrode of a surface acoustic wave device even when a short-circuit region 6 not exposed to a resist, such as a boundary portion between a region with a shifter and a region without a shifter in FIG. It is an object of the present invention to provide a comb-shaped light-shielding film pattern and a shifter pattern in a glass mask that does not short-circuit.

[0017]

A surface acoustic wave device according to the present invention.
The method of manufacturing is a light shielding pattern for a comb tooth
Glass with a shifter at a position
Exposure using a mask to form a comb electrode pattern on the substrate
It is characterized by the following .

In the present invention, a comb-shaped light-shielding pattern composed of a rectangular light-shielding pattern and a common electrode part light-shielding pattern has a shape that blocks light formed on a transparent glass substrate. This shape can also be formed with a metal thin film on a transparent glass substrate.

In the glass mask for light exposure of the present invention, the translucent thin film serves as a shifter.

The translucent thin film serving as a shifter is formed for each set of light-shielding patterns as described above. Therefore, the lengths of the rectangles of one set of light-shielding patterns must be the same, but the lengths of all the sets need not be the same.

[0021]

When a substrate of an electronic component is exposed to light using the glass mask for light exposure of the present invention, light is applied to the end of the light-shielding pattern, which is a set of two, on the side opposite to the connection with the common electrode. There is a region where the intensity becomes zero, and a short circuit portion of the pattern occurs at the boundary of the shifter film.

However, since the two comb electrodes are connected by the same common electrode, even if a short circuit occurs at a portion corresponding to the boundary of the shifter film, the operation of the surface acoustic wave device is not affected. No inconvenience occurs.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a surface acoustic wave device will be described below with reference to the drawings.

FIG. 1A shows a comb-shaped light-shielding pattern of a glass mask for light exposure using the phase shift method of the present invention.

A set of two light-shielding patterns 8 or 9 having a width of about d and a length of l is provided at an interval of about d in the width direction, and one set of light-shielding patterns is arranged at an interval of about 5d. The comb-shaped light-shielding pattern connected to the common electrode light-shielding pattern 10 or 11 at the end of the pattern 8 or 9 and orthogonal to the common electrode part light-shielding pattern 10 or 11 is set such that the distance between the light-shielding pattern 8 and the light-shielding pattern 9 becomes substantially d. At least one set of light-shielding patterns, and a width starting from substantially the center of the width of one light-shielding pattern of one set of light-shielding patterns and ending at substantially the center of the width of the other light-shielding pattern; Or 11 has a length that starts from at least the inside of the end face on the connection portion side and ends at substantially the other end of the common electrode light-shielding pattern 10 or 11 of the set of light-shielding patterns. The light of the thin film 12 was formed on each pair of the light-shielding pattern. In addition, a translucent thin film 1 serving as a shifter
The film thickness of 2 was set to λ / {2 (n−1)}, where λ is the wavelength of light used for light exposure and n is the refractive index of the light-transmitting thin film 12.

The substrate of the electronic component was exposed to light using the glass mask of FIG.

As a result, a light intensity pattern of the interdigital electrode focusing on the substrate as shown in FIG. 1B was obtained. In this case, a pattern 13 that short-circuits the patterns 14 or 15 corresponding to one set of electrodes is formed.

However, the pattern 14 or 15 corresponding to one set of electrodes is the first pattern corresponding to the common electrode.
Since the connection is made by 6 or 17, even if the patterns 14 or 15 corresponding to one set of electrodes are short-circuited, the intersecting comb-shaped electrodes are not short-circuited, which causes a problem in the operation of the surface acoustic wave device. There is no.

Further, the contrast of the light pattern when transferred onto the substrate was increased, and a finer tooth-shaped electrode could be formed.

[0030]

According to the glass mask for light exposure of the present invention, a rectangular light-shielding pattern having a width of substantially d is formed as a set of two light-shielding patterns having the same length in parallel in the width direction at intervals of substantially d. At least two sets of the one set of light-shielding patterns are arranged in parallel at intervals of about 5d, and the light-shielding patterns are connected to a common electrode part light-shielding pattern at an end of the light-shielding pattern and at a position orthogonal to the common electrode part. A light-exposing light-shielding pattern formed by intersecting a comb-shaped light-shielding pattern such that the interval between the light-shielding patterns is substantially d, starting from substantially the center of the width of one light-shielding pattern of the set of light-shielding patterns. A width ending substantially at the center of the width of the other light-shielding pattern; A light-transmitting thin film having a length ending at the other end of the pair of light-shielding patterns to be connected is formed for each of the pair of light-shielding patterns, and the wavelength of light used for light exposure is set to λ. When the refractive index of the transparent thin film is n, the thickness of the transparent thin film is λ / ｛2
Since (n-1)｝, a light-shielding film pattern and a shifter pattern in a glass mask which did not short-circuit the interdigital electrode were obtained.

Therefore, the phase shift method can be used for a glass mask for manufacturing a surface acoustic wave device having a comb-shaped electrode, and a finer comb-shaped electrode can be formed. Wave devices can be manufactured. In addition, the present invention can be applied to semiconductors and the like, so that a finer semiconductor integrated circuit can be manufactured.

[Brief description of the drawings]

FIG. 1A is a diagram showing a glass mask using the phase shift method of the present invention, and FIG. 1B is a diagram showing light focused on a substrate of an electronic component when light exposure is performed using the glass mask. It is a figure showing an intensity pattern.

FIGS. 2A to 2C are diagrams showing a light exposure method when a phase shift method is not used, and FIGS. 2D to 2F show light exposure methods when a phase shift method is used. FIG.

3A is a diagram showing a glass mask when performing light exposure of a surface acoustic wave device using a conventional phase shift method, and FIG. 3B is a diagram illustrating a case where light exposure is performed using this glass mask. FIG. 3 is a diagram illustrating a light intensity pattern focused on a substrate of an electronic component.

4A is a cross-sectional view corresponding to AA or BB of the glass mask of FIG. 3A, and FIG. 4B is a diagram illustrating a distribution of the amplitude of light focused on a substrate material. FIG.
(C) is a diagram showing the distribution of the light intensity focused on the substrate material.

[Explanation of symbols]

1 ... glass substrate, 2 ... light-shielding pattern, 3 ... shifter, 4 and 5 ... comb-shaped light-shielding pattern, 6 ... short-circuit area, 7 ... boundary part of shifter, 8 and 9 ... light-shielding pattern, 10 and 11: common electrode part light-shielding pattern,
12: translucent thin film, 13: short circuit pattern, 14 and 15: light intensity pattern corresponding to one set of electrodes, 1
6 and 17: Light intensity patterns corresponding to the common electrode.

Claims (1)

(57) [Claims] 1. A light-shielding pattern for a comb-shaped electrode in which two pieces constitute one set.
Glass with a shifter at a position
Exposure using a mask to form a comb electrode pattern on the substrate
A method for manufacturing a surface acoustic wave device.