JPS58204532A - Formation of pattern - Google Patents

Abstract

PURPOSE:To obtain a resist pattern constituted by parts different in thickness from each other, with a high accuracy, by a method wherein a resist layer constituted by two layers different in sensitivity from each other is exposed so as to be partially varied in intensity of the light applied thereto, and is then developed. CONSTITUTION:A layer 1 to be processed is coated with a photoresist film 2 with a thickness of about 0.3mum, which is pre-baked to lower the sensitivity thereof. A photoresist film 4 of the same material is applied with a thickness of about 0.3mum through a polyethylene chloride thin film 3 and is pre-baked at an oridinary pre-baking temperature so as to maintain an ordinary sensitivity. A selective exposure is effected through a mask 6 having patterns 8 and 7 different in transmittance of light 9 from each other to remove a sensitized region 4' of the film 4 through development. The exposed resin film 3 is removed by plasma ashing. Then, a sensitized region 2' of the film 2 is removed through development, to obtain a stair-shaped resist pattern with a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pattern forming method, and more particularly, the present invention is suitable for forming at least two or more layers of a pattern in a bubble memory element or a semiconductor device. What?
This invention relates to a pattern forming method.

Conventionally, for example, in order to create two types of patterns with different materials and shapes on a substrate, the usual 7 otolithography steps, that is, the vapor deposition of the pattern material and the photo-etching step, are performed twice. I needed to give it back. In response, a method has been proposed that improves the photophosphorography process and creates two types of patterns with different materials and shapes on a substrate using -times of fog light (% 1986-139268
).

In this method, first, a single-layer resist film is exposed to light through a photomask consisting of first and second patterns having partially different light transmittances, and light having partially different light intensities is applied to the resist film. By irradiating and causing a phenomenon, first and second resist patterns having partially different film thicknesses corresponding to the mask patterns are formed. The method is characterized in that the first and second resist patterns are used as masks to produce the resist pattern.

However, since the conventional method described above uses a single-layer resist film, there are problems described below. That is, to explain the case of a positive type photoresist as an example, in the resist, the portion exposed to fog light dissolves, and after development, the unexposed portion remains as a pattern. Therefore, the transmittance is different from each other.
When this is irradiated with light through a photomask composed of a seed pattern, a soluble region and a semi-soluble region are formed, and after development, two patterns with different film thicknesses are formed. The processing conditions for leaving this bovine soluble region as a pattern do not satisfy the original resist properties, so there has been a drawback that stability, reproducibility, and controllability are significantly poor. Therefore, it was extremely difficult to obtain two patterns with different film thicknesses with high accuracy.

The object of the present invention is to solve the above-mentioned conventional problems, and to form two types of resist films with different film thicknesses in -times of exposure. ''/fS/fS By irradiating and developing light with different intensities, resist patterns with partially different thicknesses are formed with commercial accuracy.

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a process diagram showing one embodiment of the present invention. 1st
As shown in FIG.
Coat to a thickness of μm.

The first photoresist group 2 was subjected to a pre-bake for 120 minutes to make it less sensitive.Another method for making the photoresist group 2 less sensitive was, for example, by pre-baking a seed of a photosensitive group.

Next, as the intermediate resin film 3, chlorinated polyethylene was made with a thickness of 150 nm.
Apply to a thickness of . Further, as the second photoresist film 4, AZ150J is applied to a thickness of 0.3 μm.

The temperature for baking at this time was 80C for 20 minutes to achieve normal sensitivity.

As shown in FIG. 1(b), the laminated first and second patterns are interposed through a radiation mask 6 consisting of a first pattern 8 and a second pattern 7 having different transmittances for light 9. The resist film 2.4 is exposed. Regions 4' of the second resist group 4 include transparent parts of the mask 6 and the first
It is exposed to light that has passed through the pattern 8, and is exposed to light. The first resist group 2 is exposed in the same way, but since it has lower sensitivity than the second film 4, the exposed area 2' is exposed to the high intensity light that has passed through the transparent part of the mask 6. The portions irradiated by the weak light that has passed through the first pattern 8 are not exposed to light.

Next, as shown in FIG. 1C, the exposed area 4' of the second resist film 4 is removed by development. The exposed intermediate resin film 3 is removed by a well-known oxygen plasma etching method.

As shown in FIG. 1(d), the exposed area 2' of the first resist film 2 is removed by a development process, and the first and second resist films 2' are removed.
A step-like resist pattern with different thicknesses was obtained using the resist film 2.4.

Although AZ1350J was used as the photoresist in this embodiment, the same pattern can be formed using other photoresists, such as a negative type resist such as OMR-83, but the structure of the pattern is reversed.

The intermediate resin film is used to prevent the first resist film formed below from dissolving when two resist films are laminated. That is, in the above implementation, both the first and second resist films are AZ.
1350J was used, but since both are dissolved in the same solvent, the first resist film is dissolved when the second resist film is applied. Therefore, an intermediate resin film is provided on the wfJl resist a to prevent the first resist film from dissolving. When the first and second resist films have different solvent properties, it is not necessary to provide an intermediate resin film.

Further, it is preferable that the first and second resist films have different sensitivities to irradiation light. For example, when a positive photoresist is used, the sensitivity of the second resist m is higher than that of the first resist film. Preferably high.

As explained above, according to the present invention, Stella C
Good) It is possible to form a bubble-shaped resist pattern with high precision. 1. In magnetic bubble memory elements and semiconductor integrated circuits, patterns with different shapes can be formed in a 111 mL volume.

It is extremely useful for forming structures that

[Brief explanation of drawings]

FIG. 1 is a process diagram showing one embodiment of the present invention. (
'. ) 1... layer to be processed, 2... first resist film,
3... Intermediate resin film, 4... Second resist group, 6...
...Mask, 7...Second (opaque) pattern, 8.
...First (semi-transparent □ (LL) 11 Figure

Claims (1)

[Claims] 1. A pattern forming method including the following steps (1) A step of laminating and depositing a first resist film, a resin film, and a second resist film on the workpiece j-. (2) In desired areas of the first and second resist films,
A process of selectively irradiating light with partially different intensities. (3) Developing the second resist film. (4) A step of removing the exposed portion of the resin film. (5) A step of developing the first resist film to form a resist pattern with partially different thicknesses.