JPH0552076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of etching a thin film pattern formed on a substrate, particularly wet etching using a resist film.

(Prior Art) Conventionally, for example, when forming a heating element of a thermal head, a light emitting diode (LDE), etc.
When forming a bonding recognition mark for a printer head (light emitting diode), a minute pattern having a minute opening area is formed in a thin film on a substrate. When forming micropatterns, it is common practice to sequentially etch a plurality of thin films in order to reduce the number of steps in the photolithography process. Such minute patterns are
Plasma etching and RIE (Reactive Ion)
According to a dry etching method such as Etching), it can be formed relatively easily.

However, since the dry etching method is an etching method using physical means, the resist film used for forming the openings is seriously damaged, making it difficult to peel off the resist film after etching is completed. There is also a method of using the upper thin film in place of the resist film without using the resist film, but in this case, the upper thin film may react with the gas used during dry etching and the properties of the upper thin film may be damaged. .

A wet etching method is available as a method for avoiding the above-mentioned disadvantages of the dry etching method. This wet etching method uses an etching solution to remove portions of the thin film that are not covered by the resist film.

Conventionally, as a method of etching a thin film pattern by this type of wet etching, methods as shown in FIGS. 2 to 4 have been used.

2 is a plan view of the substrate before etching, FIG. 3 is a sectional view taken along the line A--A in FIG. 2, and FIG. 4 is a sectional view of the substrate in FIG. 3 after etching.

In FIGS. 2 and 3, a first layer thin film 2 is formed on a substrate 1, a second layer thin film 3 is further formed thereon, and then a resist film 4 is formed on the second layer thin film 3. . Next, an opening pattern 5 and a micro pattern 6 having a predetermined opening area are formed in the resist film 4. This minute pattern 6 is for forming the bonding recognition mark, etc., and has a minute opening area compared to the opening area of the opening pattern 5.

Next, by performing wet etching using an etching solution, an opening pattern 5 is formed as shown in FIG.
Then, the second layer thin film 3 exposed to the micro pattern 6 and the first layer thin film 2 below it are removed.

(Problems to be Solved by the Invention) However, the above-mentioned thin film pattern etching method has the following problems.

(1) The second layer thin film 3 exposed to the micro pattern 6 is
If the resist film 4 is thin, for example, about 5 μm, it can be easily etched. However, the first
When the layer thin film 2 is successively etched, the surface to be etched has a step with respect to the surface of the resist film 4 corresponding to the film thickness of the resist film 4 and the second layer thin film 3. Since this level difference is too large relative to the opening area of the micropattern 6, it becomes difficult for the etching solution to penetrate.

Furthermore, when a highly viscous etching liquid such as phosphoric acid is used, the surface tension of the liquid surface is large, making it even more difficult for the micropattern 6 to penetrate into the surface to be etched.

In this way, if the etching liquid is insufficiently permeated into the surface to be etched of the micro pattern 6,
This results in quality and reliability problems such as an increase in etching defects and a decrease in etching accuracy.

(2) In order to prevent the above-mentioned problem from occurring, there is a method of etching that takes a sufficient amount of time, but in this case, etching is performed over a larger area than necessary in the part of the opening pattern 5 to be etched. , there was a risk that so-called over-etching would occur.

The present invention solves the problems of the prior art described above, such as an increase in etching defects and a decrease in etching accuracy at the etched portions of the micro pattern 6, or a risk of over-etching at the etched portions of the opening pattern 5. The present invention provides a thin film pattern etching method that solves certain problems.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a step of applying a resist to the surface of a thin film formed on a substrate to form a resist film, and a step of forming a resist film on the surface of a thin film formed on a substrate. forming an opening pattern having a predetermined opening area and a minute pattern having an opening area smaller than the opening pattern; and after forming the opening pattern and the minute pattern, performing wet etching on the thin film using an etching solution. In the method for etching a thin film pattern, the method includes forming a connection pattern in the resist film that connects the opening pattern and the micropattern through an opening, and guiding the etching solution from the opening pattern to the micropattern through the connection pattern. This is how it was done.

(Function) According to the present invention, since the thin film pattern etching method is configured as described above, the connected pattern serves as a channel for guiding the etching solution of the opening pattern to the minute pattern, and the connected pattern serves as a channel for guiding the etching solution of the opening pattern to the minute pattern to be etched. It works to ensure that the target is reached. Furthermore, it prevents the etching solution from stagnation and promotes its flow, so that quick and reliable etching can be performed.
Due to the operation of such a connected pattern, there is no need to spend a long time on etching, and there is no risk of over-etching in the opening pattern. Therefore, the above problem can be eliminated.

(Example) Figure 1 shows an example of the present invention. Figure 5 is a plan view of a substrate on which a thin film and a resist film are formed before etching. Figure 5 shows the substrate in Figure 1 cut along line B-B. FIG. 6 is a perspective view of the substrate of FIG. 5 after etching.

The method for etching a thin film pattern will be explained below for each step.

(A) First step In FIGS. 1 and 5, a first layer thin film 12 is formed on the surface of a substrate 11 made of, for example, silicon or alumina. On top of that, a second layer thin film 13
After forming, a resist film 14 is formed on the second layer thin film 13.

This resist film 14 is made by dissolving a resist made of, for example, a photosensitive organic substance in an organic solvent, dropping a small amount of this onto the second layer thin film 13, and rotating the substrate 11 at high speed to coat the entire surface of the second layer thin film 13 with the resist. It can be formed by coating it in different ways.

(B) Second step After forming the resist film 14, for example, irradiating ultraviolet light through a photographic plate with a predetermined pattern,
When immersed in a developer, only the exposed portions are left and the rest are removed, resulting in a desired pattern on the resist film 14. When forming a pattern on the resist film 14 in this way, an opening pattern 15 and a micro pattern 16 are formed, and a connecting pattern 17 connecting these through the opening is formed.

(C) Third step Predetermined patterns 15, 1 are formed on the resist film 14.
After forming 6 and 17, if etching treatment is performed using an etching solution such as hydrochloric acid, the second thin film layer 13 of the opening pattern 15, minute pattern 16 and connection pattern 17 that is not covered by the resist film 14 is etched. The first thin film layer 12 is then etched.

At this time, the minute pattern 16 is connected to the connected pattern 1.
Since the etching liquid is connected to the opening pattern 15 by the connecting pattern 17, the etching liquid is guided by the connecting pattern 17 and quickly flows into the micro pattern 16. In addition, the etching solution is prevented from staying in the micropattern 16 and its flow is promoted, so etching in the depth direction from the second thin film layer 13 to the first thin film layer 12 is performed reliably and quickly. .

When the etching is completed in this way, the sixth
As shown in the figure, the second
As with the shape of the thin film layer 13 and the first thin film layer 12 under the opening pattern 15, desired highly accurate shapes can be obtained.

Thereafter, the remaining resist film 14 is removed using an organic solvent, oxidation, or the like.

In this embodiment, since the etching method is used to form the connection pattern 17 on the resist film 14, there is an advantage that the etching under the minute pattern 16 can be performed efficiently, reliably, and with high precision. Therefore, for example, it becomes easy to form a heating element for a thermal head, a bonding recognition mark for an LED printer head, etc., and also improve the yield and reliability. Further, since the etching under the minute pattern 16 and under the aperture pattern 15 is performed substantially equally at the same time, there is no risk of over-etching at the portion to be etched under the aperture pattern 15.

Note that the present invention is not limited to the illustrated embodiment and can be modified in various ways, such as the following modifications.

(i) In FIGS. 5 and 6, the layers to be etched are two layers, the first thin film 12 and the second thin film 13, but the invention is not limited thereto. For example, it may be one layer, or it may be three or more layers.

(ii) During the etching process, the resist film 14
Thereafter, the entire resist film 14 may be immersed in the etching solution, or the resist film 14 may be coated with the etching solution.

(iii) The number of connected patterns 17 to be formed is not limited to one per minute pattern 16, for example, two.
Can be individually formed.

(iv) The materials of the substrate 11, resist film 14, etching solution, etc. are not limited to those shown in the above embodiments. Furthermore, the shapes, numbers, etc. of the opening pattern 15, minute pattern 16, connection pattern 17, etc. are not limited to those shown in the drawings, and can be modified in any manner.

(Effects of the Invention) As described above in detail, according to the present invention, the etching method forms a connection pattern connecting the opening pattern and the micropattern in the resist film, so that the etching location under the micropattern can be quickly and easily etched. A reliable etching process can be performed.
Therefore, it is possible to improve yield and pattern accuracy, and to manufacture highly reliable thin film etched substrates.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention; FIG. 2 is a plan view of a substrate on which a thin film and a resist film are formed before etching; FIG. 2 is a plan view of a conventional substrate before etching; FIG. FIG. 4 is a sectional view of the substrate shown in FIG. 3 after etching, FIG. 5 is a perspective view of the substrate shown in FIG. 1 taken along line B-B, and FIG. 6 is a perspective view of the substrate of FIG. 5 after etching; FIG. 11... Substrate, 12... First layer thin film, 13...
2nd layer thin film, 14...resist film, 15...opening pattern, 16...micro pattern, 17...connection pattern.

Claims (1)

[Claims] 1. A step of forming a resist film by applying a resist to the surface of a thin film formed on a substrate, an opening pattern having a predetermined opening area in the resist film, and a comparison with the opening pattern. A method for etching a thin film pattern, comprising: forming a micropattern having a small opening area; and performing wet etching on the thin film using an etching solution after forming the opening pattern and the micropattern, 1. A method for etching a thin film pattern, comprising forming a connection pattern that connects an opening pattern and a micropattern through an opening, and guiding the etching solution from the opening pattern to the micropattern through the connection pattern.