JPS5892224A - Pattern formation - Google Patents

Abstract

PURPOSE:To form a sharp and fine pattern by a method wherein a positive-type resist is applied after applying one or more-layer resin film on a predetermined substrate and the resin thin film is eliminated by using plasma etching after exposing and developing a predetermined figure on the positive-type resist. CONSTITUTION:A silicon substrate is used as a substrate 1, and PBS is used as a resin thin film 6 and after applying the film 6 on the Si substrate, prebaking is performed, followed by the prebaking again by applying AZ2400. Litht exposure is performed by using a predetermined mask. Next, the AZ2400 is developed and then etching is done with the aid of a facing electrode-type plasma etching device. Loss of the AZ2400 film hardly exists in this process and a fine pattern can be formed. The PBS just under a window section is etched by executing etching with the aid of a cylindrical plasma etching device and it was possible to form a pattern shape suitable for lift off.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a pattern suitable for lift-off and a method of forming a fine pattern on a predetermined substrate using a resin film and a positive resist.

2. Description of the Related Art As semiconductor devices become more integrated, the need to form finer patterns becomes more complex. In order to form a thin pattern, it is necessary to thin the resist layer applied to the substrate. However, when the 1/cyst layer is made thinner, problems such as pinholes are more likely to occur or uneven substrates are insufficiently covered. Therefore, there is a limit to how thin the resist layer can be made, and this has limited the ability to make patterns finer. still,
When forming a pattern using electron beam exposure, electrons that are backscattered from the substrate and returned to the resist contribute to the exposure, so the amount of exposure in the resist layer closer to the substrate is stronger, and the exposure in this resist is increased. Changes in the amount hindered resist miniaturization.

On the other hand, in order to form a predetermined metal figure on the substrate, the rift 1-
A method called off is often used.

In this lift-off method, pattern formation is performed through the process shown in FIG. That is, as shown in FIG. 1(d),
After coating a resist film 2 on a predetermined substrate 1, exposure and development are performed to form a predetermined window pattern 3 [FIG. 1(b)].Furthermore, a metal film 4 is deposited on this to form a predetermined window pattern 3 (FIG. 1(b)). By obtaining the substrate structure shown in C) and then removing the resist film 2,
The metal film on this is removed at the same time, and a predetermined metal film figure 5 is formed.
[Fig. 1(d)].

By the way, the cross-sectional shape of the resist pattern that is actually formed is not as shown in FIG. 1, but is usually as shown in FIG.
), it has an inverted trapezoidal shape. Therefore, when the metal film 4 is deposited on the substrate on which the pattern of the resist film is formed, as shown in FIG. There was an inconvenience that the metal figures 6 were connected to each other, making it difficult to form a predetermined metal figure 6 by lift-off.

The present invention involves coating a predetermined substrate with one or more resin films, then coating a positive resist, exposing and developing a predetermined pattern on the positive resist, and then removing the resin thin film using plasma etching. According to the present invention, two problems can be solved, and fine patterns can be formed using plasma etching, which strongly etches in the direction perpendicular to the substrate. By performing isotropic plasma etching, a pattern suitable for lift-off can be formed.

The present invention will be explained in detail below with reference to FIG.

First, as shown in FIG. 3(a), a resin thin film 6 is applied onto a predetermined substrate 1, prebaked, and then a resist film 2 is applied and prebaked again. Note that the resin thin film 6 described above may be a resist or a non-photosensitive resin.

Next, a predetermined pattern is exposed and developed to form a window 3 in the resist film 2 as shown in FIG. 3(b). By using the resin thin film 6 that is insoluble in this developer, the resin thin film 6 remains as it is. Here, the exposure may be light exposure or electron beam lightning, but X-ray exposure or ion beam exposure may also be used.

Thereafter, the thin resin film 6 exposed within the window 3 is etched using a counter-electrode type plasma etching device to form a pattern as shown in FIG. 3(c). The pattern formed through the above process becomes extremely fine. Although a single layer resin thin film has been described here, it is also possible to form a multilayer resin thin film.

Next, when the thin resin film 6 is subjected to an isotropic etching process using a cylindrical plasma etching apparatus, the thin resin film 6 is etched as shown in FIG. 3(d). This shape is suitable for lift-off in which the resist film 2 protrudes like a ridge.

FIG. 3 (6) is a diagram showing the state after a metal film is formed on the substrate which has undergone the above-mentioned treatment.As shown in the figure, the metal film 4 on the resin film and the metal film on the substrate 1 The figure 6 is completely separated. Therefore, by removing the resist film 2, the metal film 4 thereon can be removed at the same time, and the metal film figure 6 can be removed.

Next, a specific example will be explained based on FIG.

A silicon (Sl) substrate is used as the basic 1, and a resin thin film 6 is used.
PBS, also known as positive electron beam resin
(Polypuran Sulfone) and AZ 2400 as resist layer 2. After applying PBS to a thickness of 1 μm on the 81 substrate, a 160G prebaking was performed for 10 minutes. Apply AZ2400 to a thickness of 0.571 m and
Pre-bake again at 0'C for 10 minutes. Light exposure is performed using a predetermined mask.

Next, develop AZ2400 using KAZ2401 developer. After that, using a facing electrode type plasma etching device, the RF output was 200W, the pressure was 0.3Tovr,
Etching is performed for 30 seconds under the condition of etching gas O2. In this process, there is almost no film periphery of AZ 2400, and a fine pattern with a minimum spacing of 0.5 μm can be formed.

A cylindrical plasma etching device is used to form a pattern suitable for lift-off.

By etching for 6 minutes under the conditions of RF output 200 W, pressure 2 T□vr, and etching gas 02, the PBS directly under the window was etched, and by side etching, a pattern shape suitable for lift-off could be formed. .

As detailed above, according to the present invention, even if the substrate is uneven, by applying a resin thin film, the unevenness can be alleviated and made flat, and the occurrence of pinholes can be eliminated. Therefore, a positive resist layer can be applied thinly, and since the resist is finally removed by plasma etching, no resist residue is generated, and a fine pattern with good sharpness can be formed. However, by using isodirectional plasma etching, the resin thin film is side-etched, and a pattern with a shape suitable for lift-off can be formed.

[Brief explanation of the drawing]

Figures 1 (IL) to (d) are process cross-sectional views explaining lift-off, Figures 2 (2L) and (b) are cross-sectional views of conventional lift-off processes, and Figures 3 (IL) to (el) are FIG. 2 is a cross-sectional view illustrating a method of forming a fine pattern and a method of forming a pattern suitable for lift-off according to an embodiment of the invention. 1...Substrate, 2...Bong-type sinuto,
3... Window, 4... Metal film, 6...
...Metal film figure, 6...Resin thin film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 (C) [d) [ε)
5

Claims (1)

[Claims] After applying one or more layers of resin film on a predetermined substrate, applying a positive resist, exposing and developing a predetermined pattern on the positive resist, and then removing the resin thin film using plasma etching. Characteristic pattern formation method.