JPH06267835A - Patterning method of thin film - Google Patents

Abstract

PURPOSE:To prevent resist from peeling in the cource of patterning, by processing with oxygen plasma the surface of a silicon nitride film or a silicon oxide film before resist coating. CONSTITUTION:A silicon oxide nitride film (Si0N, reflectivity 1.82) is deposited on a silicon single crystal substrate by using plasma CVD. A very thin silicon oxide film (SiO2) layer 7 is formed on the surface of a thin film by an oxygen plasma processing apparatus and spin-coated with positive resist HPR-204D manufactured by Fuji Hunt Co., Ltd. After a line figure having various kinds of stripe width is exposed by using a stepper aligner, development is performed with developer 429E manufactured by Fuji Hunt Co., Ltd. The substrate is dipped in 25:1 (NH4 F:HF) BOF (buffered oxide etcher) for 500min.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a silicon nitride thin film (S
i ₃ N ₄ ) or silicon oxynitride thin film (SiON) can be applied to all devices, but at present, the invention is particularly useful for silicon semiconductor products.

[0002]

2. Description of the Related Art Usually, a silicon nitride thin film (Si ₃ N ₄ )
Alternatively, in a device using a silicon oxynitride thin film (SiON), these thin films are rarely used as they are, and the thin films are often patterned after depositing these thin films. This patterning is usually performed by applying a photoresist on the thin film, exposing and developing the pattern, and then etching the thin film and removing the resist.

[0003]

In the above prior art, since the adhesion between the silicon nitride thin film (Si ₃ N ₄ ) or silicon oxynitride thin film (SiON) and the photoresist is poor, the resist is patterned during patterning. There was a problem that it came off. This problem has been a serious problem especially when wet etching is performed after resist patterning. This is because when wet etching is performed, the lower part of the resist is etched and dug away, and the resist is easily peeled off. This will be described below with reference to the drawings. In FIG. 1A, a silicon oxynitride film 2 is deposited on a substrate 1. After that, the resist 3 is applied to the entire surface, and the state shown in FIG. Next, the resist pattern 4 is left by exposing and developing the pattern. This is the state shown in FIG. Next, this is subjected to wet etching. Resist pattern 4 here
If the adhesion between the silicon oxynitride film 2 and the silicon oxynitride film 2 is poor, the side etching width 5 becomes large, and finally the resist pattern 4 is formed.
Is peeled off. This state is the state shown in FIG. In this case, normal patterning cannot be performed, and the resist 6 that has peeled off becomes dust, resulting in a decrease in yield.

[0004]

The present invention solves the above problems by subjecting the surface of a silicon nitride film (Si ₃ N ₄ ) or a silicon oxynitride film (SiON) to oxygen plasma treatment before resist coating. It is what

[0005]

[Function] By subjecting the surface of the silicon nitride film (Si ₃ N ₄ ) or the silicon oxynitride film (SiON) to oxygen plasma treatment, the surface of the thin film becomes a silicon oxide film (SiO ₂ )
Can be close to. However, since the adhesiveness of the resist to the surface of the silicon oxide film (SiO ₂ ) is good, the resist peeling as shown in FIG. 1E can be prevented. This action will be described below with reference to an embodiment.

[0006]

EXAMPLE A silicon oxynitride film (SiON, refractive index 1.82) is deposited on a silicon single crystal substrate by plasma CVD. This state is shown in FIG. Next to this
By applying the oxygen plasma processing apparatus, an extremely thin silicon oxide film (SiO ₂ ) layer 7 is formed on the surface of the thin film.
In this embodiment, as the oxygen plasma processing apparatus, an apparatus called an asher which is usually used for resist stripping is used. This state is shown in FIG. Thereafter, a positive resist HPR-204D manufactured by Fuji Hunt was spin-coated to obtain the state of FIG. Next, after a line pattern having various line widths was exposed using a stepper exposure device, development was performed with a developer 429E manufactured by Fuji Hunt to obtain the state of FIG. 2 (d). Next, this substrate is changed to 35: 1 (NH ₄ F: H
F) BOE (buffered oxide etcher)
Was soaked for 500 seconds. This state is shown in FIG. The side etching width 5 at this time was 0.5 μm. On the other hand, under the same conditions for film formation and etching, as shown in FIG.
Side etching width when performing the conventional process of 5
Was 2.0 μm.

[0007]

As is readily apparent from the examples, the present invention significantly improves the adhesion between the thin film and the resist. As a result, peeling of the resist can be effectively prevented. This effect is also effective in normal resist patterning, but it brings a great effect particularly when wet etching is performed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a wet etching process according to a conventional technique.

FIG. 2 is a diagram showing a wet etching process according to the present invention.

[Explanation of symbols]

1 Substrate during thin film deposition 2 Silicon oxynitride thin film 3 Applied resist 4 Patterned resist 5 Side etching width during wet etching 6 Resist removed by side etching 7 Silicon oxide film layer formed on the surface by oxygen plasma treatment

Claims (1)

[Claims] 1. When patterning a silicon nitride film (Si ₃ N ₄ ) or a silicon oxynitride film (SiON) using a photoresist, an oxygen plasma treatment is applied to the film surface before applying the resist. Method for patterning thin film.