JPS62137856A - Formation of conductor pattern - Google Patents

Abstract

PURPOSE:To prevent attachment of unnecessary conductor metal to the edge of a conductor pattern, by quickly performing osmosis of peeling liquid into a resist film, and shortening a peeling time, when the resist film is removed after the conductor metal is evaporated in a lift-off method. CONSTITUTION:At first, a first resist film 14 is formed on a piezoelectric substrate 14. By using a mask 15, which is obtained by reversing a pattern having about the equal width as that a desired conductor pattern, exposure is performed to ultraviolet rays. A fusible part corresponding to the conductor pattern is dissolved and fused with developing liquid. Then an Al evaporated film 16 is formed on the surface of a substrate 13. A second resist film 17 is formed on the film 16. Thereafter, by using a second mask 18, which has the pattern equal to the desired conductor pattern, exposure is performed to the ultraviolet rays. A fusible part corresponding to the conductor pattern and the reversed pattern are formed. Thereafter the fusible part of the film 17 is dissolved and removed. The device is immersed in etching liquid. The film 16 formed on the side surface of the film 14 is removed. Thereafter, the remaining films 14 and 17 are dissolved and removed by a peeling liquid together with the film 16 remaining on the film 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of forming a conductor pattern using a lift-off method.

[Technical background of the invention and its problems] Conventionally, for example, in la of a surface acoustic wave element, a conductor pattern such as a comb-teeth electrode 2.2 is placed on a piezoelectric substrate 1, as shown in FIG. When forming, generally the fourth
This is done by the method shown in the figure.

As shown in the figure, first, aluminum (
(hereinafter referred to as A°C) to form a vaporized film 4 (Figure 4-A),
A resist film 5 is formed on this (FIG. 4-B).

Thereafter, an unexposed portion 5a corresponding to the pattern is formed on the resist film 5 by exposure using a mask 6 having a pattern equal to the desired conductor pattern.
C) The exposed portion 5b of this resist film 5 is dissolved and removed (FIG. 4-D).

And exposed A! The portion 4a of the deposited film is etched (FIG. 4-F), and then the unexposed pattern 5 of the resist film 5 is etched.
This is done by removing a (FIG. 4-F).

However, in this method, for example, L! When using a piezoelectric substrate such as 2B407, the piezoelectric substrate is eroded by the etching solution, so a conductor pattern is formed on the piezoelectric substrate by a riff 1-off method.

FIG. 5 is a diagram showing a process of forming a conductor pattern using the conventional lift-off method.

In this method, first, a positive resist film 8 (hereinafter simply referred to as a resist film) is formed using a photosensitive resist or the like on the piezoelectric substrate 7 (Fig. 5-8), and then a pattern that is inverted from the desired conductor pattern is formed. The resist film 8 is exposed using the mask 9 (FIG. 5-B).

Thereafter, the exposed portion 8a of the resist film 8 is dissolved and removed using a developer to form an inverted pattern 8b on the piezoelectric substrate 7 (FIG. 5-○). After that, β evaporation is carried out on this inverted pattern 8b. The film 10 is formed (FIG. 5-D), and the unexposed pattern 8b is removed together with the AA vaporized film 10a formed thereon using a stripping solution to form a desired conductor pattern 10b on the piezoelectric substrate 7.
(Fig. 5 (>.

However, in the conventional 1-noft-off method described above, the 6th
As shown enlarged in the figure, in the process of forming the A° C. vapor deposited film 10, an Affl vapor deposited film 10a is also formed on the side surface (edge portion) of the unexposed pattern 8b.

In other words, the stripping liquid of the unexposed pattern 8b penetrates from the edge portion of the unexposed pattern 8b where the A.degree. C. vapor deposited film 10a is thin and has cracks.
A vapor deposited film 10a is formed. Therefore, it takes time for the stripping solution to penetrate, and stripping becomes extremely difficult, especially when the edge portion of the unexposed pattern 8b has a gentle slope.

Also, as in surface acoustic wave devices, as the frequency increases, the electrode line width becomes thinner, resulting in a more precise conductor pattern 10.
When it is necessary to form a conductor pattern 10b, the β vapor deposited film 10a deposited on the edge portion of the unexposed pattern 8b remains attached to the edge portion of the conductor pattern 10b after peeling off, as shown in FIG.

As a result, the shape of the conductor pattern 10b becomes irregular, which in turn reduces the precision of the conductor pattern 10b, causing deterioration of characteristics.

As a method for solving this problem, as shown in FIG. 8, the unexposed pattern 11b is formed into a shape like an "inverted trapezoid" and then the AJ2 vapor deposited film 12 is formed on the unexposed pattern 11b. It is conceivable that the A.degree. C. vapor-deposited film 12 is not formed on the edge portions.

However, the above-mentioned unexposed pattern 11b is shaped like an "inverted trapezoid".
Although it is possible to form a shape like this by a multilayer resist method, a chlorobenzene treatment method, etc., it is not reproducible and is extremely difficult to put into practical use.

[Object of the Invention] The present invention has been made to solve the problems of the conventional lift-off method. Penetration can be carried out quickly, thereby shortening the peeling time. It also prevents unnecessary bending of the conductor from adhering to the edges of the conductor pattern and making the shape irregular, making it possible to create precise conductor patterns. It is an object of the present invention to provide a method for forming a conductor pattern that can be formed.

[Summary of the invention].

That is, the method for forming a conductive pattern of the present invention involves forming a first resist film on a substrate, exposing the resist film to light using a first mask having a pattern that is inverse to the desired conductive pattern, and A portion of the resist film corresponding to the exposed portion is dissolved and removed, a metal vapor deposition film is formed on the surface of the substrate from which the first resist film has been dissolved and removed, and a metal vapor deposition film is formed on the surface of the substrate on which the metal vapor deposition film is formed. A second resist film is formed, exposed using a second mask having a pattern equal to the desired conductor pattern, and a portion of the second resist film corresponding to the exposed portion is dissolved and removed. By removing the metal vapor deposited film on the resist film and further removing the remaining first resist film and second resist film together with the metal vapor deposited film remaining on the first resist film, the stripping time is shortened. Moreover, it is possible to form a precise conductor pattern.

[Embodiment 1 of the Invention] Hereinafter, an example in which a conductor pattern of a surface acoustic wave resonator is formed on a piezoelectric substrate by the process of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the steps of the present invention.

As shown in FIG. 1, in this embodiment, a positive type photosensitive resist is first applied on the piezoelectric substrate 13 and baked to form a first resist film 14 (FIG. 1-A).

Next, this first resist film 14 is exposed to ultraviolet light using a mask 15 with an inverted pattern having a width approximately equal to that of the desired conductor pattern (as per the design value) (FIG. 1-B).
.

The solubilized portion corresponding to the conductor pattern is dissolved and removed using a developer (FIG. 1-○), and then Af! , a vapor deposited film 16 is formed (FIG. 1-D).

A high viscosity positive type photosensitive resist is roughly coated on this to a thickness sufficient to cover the level difference caused by the above process and baked to form a second resist film 17 (see Fig. 1). -F).

- Thereafter, a second mask 18 having a pattern equal to the desired conductor pattern is used to expose to ultraviolet light to form a solubilized portion corresponding to the reverse pattern of the conductor pattern (FIG. 1-F). Thereafter, the solubilized portion of the second resist film 17 is dissolved and removed using a developer (FIG. 1-G).

Then, the Affl vapor deposited film 16 formed on the side surface of the first resist film 14 is removed by immersing it in an etching solution (FIG. 1-H).

Thereafter, the remaining first resist film 14 and second resist film 17 are dissolved and removed together with the λ vapor deposited film 16 remaining on the first resist film 14 using a stripping solution (FIG. 1-■).

However, at that time, the A2 vapor deposited film 16 on the side surface of the first resist film 14 is removed by the process shown in FIG. 1-H.

As a result, the stripping solution flows from this part to the first resist film 1.
4 and is quickly peeled off together with the remaining A.degree. C. deposited film 16, and a desired conductor pattern can be precisely obtained without unnecessary A.degree. C. being deposited on the edges of the conductor pattern.

Note that although the above-described embodiments form a conductive pattern on a piezoelectric substrate, the present invention is not limited thereto. That is, as shown in FIG.
When forming the bonding butt part 21 on the conductor pattern 20 of one F-band surface acoustic wave resonator by eight β, so-called two-layer deposition can also be performed.

That is, since the film thickness of the conductor pattern 20 of one U l-(F band surface acoustic wave resonator is thin), when the A°C wire for wiring is bonded onto this, the λ wire and the conductor pattern 20 are bonded to this wiring. The adhesion becomes poor.

Therefore, after forming the conductor pattern 20, the wiring AJ2
By using the lift-off method of the present invention to increase the β film thickness of the portion where the wire is bonded, that is, the bonding pad portion 21, bonding performance can be improved.

In the actual experiment, the first resist film was 0.5μ
m, the second resist film was 2 μm thick, and the β-evaporated film was 0.3 μm thick. As a result, unnecessary A°C,
It was possible to obtain a precise desired conductor pattern without any adhesion. [Effects of the Invention] As explained above, according to the method for forming a conductor pattern of the present invention, when forming a conductor pattern by the lift-off method, a desired conductor pattern is formed on the surface of a substrate on which a metal vapor deposited film is formed. A second resist pattern having an equal pattern is formed, and the sidewall gold-deposited film of the resist pattern on the resist film of Section 1 is removed, and then the remaining first resist film and second resist film are removed. Since the resist film is removed together with the metal vapor deposited film remaining on the first resist film, the stripping solution easily penetrates into the first resist film, and the resist film can be removed by the stripping solution in a short time. Moreover, a precise conductor pattern can be formed without unnecessary conductor metal adhering to the edges of the conductor pattern.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the present invention in detail, Fig. 2 is a diagram for explaining the invention in detail, Fig. 3 is a partial perspective view showing a surface acoustic wave resonator, and Figs. FIG. 8 is a diagram for explaining a conventional method of forming a conductor pattern. 13...Piezoelectric substrate 14...First resist film 15...
...First mask 16...AJ2. Vapor deposited film 17...
...Second resist film 18...Second
Mask Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] (b) A step of forming a first positive resist film (hereinafter simply referred to as a resist film) on the substrate and exposing the resist film to light using a first mask having a pattern that is inverse to the desired conductor pattern; (b) dissolving and removing a portion of the first resist film corresponding to the exposed portion; (c)
a step of forming a metal vapor deposition film on the surface of the substrate from which the first resist film has been dissolved and removed, and (d) a step of forming a second resist film on the surface of the substrate on which the metal vapor deposition film is formed. (e) a step of exposing using a second mask having a pattern equal to the desired conductor pattern; (f) a step of dissolving and removing a portion of the second resist film corresponding to the exposed portion; g) removing the metal vapor deposited film on the first resist film; and (h) removing the remaining first resist film and second resist film from the metal vapor deposited film remaining on the first resist film; A method for forming a conductor pattern, comprising the steps of: