JPH04250624A - Pattern formation - Google Patents

Abstract

PURPOSE:To prevent the change in dimension of the SiO2 pattern after the resist patterning and etching with completely coinsided both patterns. CONSTITUTION:After a resist film 12 containing Si is formed on a semiconductor substrate 11, it is patterned. Then, the patterned resist film 12a containing Si is changed into a SiO2 film with a O2 plasma irradiation 13.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming patterns of semiconductor devices such as VLSIs, and in particular to patterning of oxide films.

0002

2. Description of the Related Art FIG. 2 is a diagram showing an example of a conventional pattern forming method for a semiconductor device. In Figure 2, Si, GaA
A SiO2 film 2 for forming a pattern is formed on a semiconductor substrate (hereinafter referred to as "substrate") 1 of approximately 3,000 to 10,000 Å by sputtering or vapor deposition.

Furthermore, on the SiO2 film 2, a resist film 3 with a thickness of approximately 2,000 to 15,000
A is formed. (FIG. 2(a)) Next, the resist film 3 is formed by photolithography, which transfers the pattern using ultraviolet light or deep ultraviolet light through a mask not shown in FIG. 2, or by directly drawing pattern data on the resist film 3. The resist pattern 3a is formed by forming an insoluble part and a soluble part in the phenomenon liquid in accordance with the pattern data using a direct electron beam drawing method or the like, and then performing a development process. (Figure 2(b))
Next, using the formed resist pattern 3a as a mask, S
By etching the iO2 film 2 with an etching gas such as CHF3, the pattern of the resist pattern 3a is transferred to the SiO2 film 2, thereby forming the SiO2 pattern 2.
a is formed. (FIG. 2(c)) Finally, the pattern 3a formed of the unnecessary resist film is removed by irradiation with O2 plasma or immersion in sulfuric acid peroxide.

In this way, Si is finally deposited on the substrate 1.
Only the pattern 2a made of the O2 film remains. (Figure 2(d))

[0005]

However, as the capacity of VLSIs increases in recent years, it is desired to form finer patterns, but as the number of transfers such as etching increases, the following problems arise.

That is, when etching a film to be processed such as a SiO2 film, if the aspect ratio of the resist pattern (the ratio of the length and width of the pattern) is high, the etching gas will not reach the film to be processed, and the etching gas will not reach the film to be processed. As a result, SiO2
The resist pattern is not transferred accurately to the film.
There is a problem in that it ultimately causes deterioration in shape and dimensions.

Furthermore, the etching selectivity between the SiO2 film and the resist film changes depending on the etching conditions such as the mixing ratio of the etching gas and the degree of vacuum, which causes a significant difference between the dimensions of the resist pattern and the dimensions of the SiO2 pattern after etching. There is a problem.

In order to prevent the dimensions of the resist pattern described above and the SiO2 pattern after etching from changing, and to maintain the shape of the SiO2 pattern in the same shape as the resist pattern, the present invention includes the steps of forming a SiO2 film pattern.
An object of the present invention is to provide a pattern forming method that does not require an etching process.

[0009]

[Means for Solving the Problems] The present invention is directed to forming a SiO2 film on a substrate without forming an SiO2 film by conventional sputtering or vapor deposition in the process of patterning the SiO2 film.
After applying a resist containing .

0010

[Operation] In the above formation method, the pattern of the Si-containing resist is converted to SiO2 when the lower resist layer is etched by O2 plasma irradiation. At this time, the resist is S
Since it is easy to convert into iO2 and has excellent resolution and adhesion, it is possible to accurately form a SiO2 film pattern in one step.

[0011]

Embodiment FIG. 1 shows an embodiment of the present invention.

[0012] On the substrate 11 is a Si-containing negative resist P.
A Si-containing resist film 12 with a thickness of about 2000 to 5000 Å is formed by rotating ACS (Oki Electric: Shin-Etsu Silicon) at 1000 to 3000 rpm using a spin coating method and heat-treating it on a hot plate at 80° C. for about 60 to 120 seconds.
form. (Fig. 1(a)) Next, the electron beam is scanned over the Si-containing resist according to the pattern data at an acceleration voltage of 20 kV and a dose of about 1 to 10 μc/cm2. The DMF
A Si-containing resist pattern 12a is formed on the substrate 11 by developing for about 10 to 60 seconds with a developer prepared by diluting (dimethylformamide) with MIBK (methyl isobutyl ketone), and then rinsing with IPA (isopropyl alcohol). . (FIG. 1(b)) After that, O2 plasma 13 is irradiated with 100 to 200 W for about 60 to 300 seconds in a 1 Torr O2 atmosphere, for example. (Figure 1
(c)) In this way, SiO is finally deposited on the substrate 11.
2 pattern 12b is formed. (Figure 1(d)
) Conventionally, Si-containing resists have been used as upper resists in two-layer resist structures. In this case, the lower layer includes OFP
When etching the lower layer resist with O2 plasma using a novolac resist with excellent plasma resistance such as R8900 (Tokyo Ohka), S
It is used to simultaneously convert the i-containing resist surface into SiO2 and provide dry etching resistance. Therefore, the resist is easily converted into SiO2, and since the Si-containing resist has excellent resolution and adhesion, it is possible to form an excellent pattern.

Furthermore, according to the present invention, if the Si-containing resist pattern is converted to SiO2, it will have excellent resistance to chemicals such as sulfuric acid and hydrogen peroxide, and will also exhibit excellent resistance to etching and chemical immersion in the next step.

[0014]

As described above in detail, according to the present invention, a pattern with good resolution is formed using a Si-containing resist, and then the pattern is converted into SiO2 using O2 plasma. Therefore, after forming the SiO2 film as in the conventional method,
A resist pattern is formed by lithography, and then the SiO2 film is etched using the resist pattern as a mask.

Furthermore, SiO
2 It is possible to form patterns, so SiO2 has excellent patterns and accurate dimensions according to the data.
Pattern formation is possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a pattern forming method according to the present invention.

FIG. 2 is a diagram showing a conventional pattern forming method.

[Explanation of symbols]

11 Semiconductor substrate 12 Si-containing resist film 12a Patterned Si-containing resist film 1
3 Plasma irradiation

Claims (1)

[Claims] 1. (a) forming a Si-containing resist film on a semiconductor substrate; (b) patterning the Si-containing resist film to form a Si-containing resist pattern; and (c) forming a Si-containing resist film on a semiconductor substrate. A pattern forming method comprising the step of irradiating a resist pattern with O2 plasma to form a SiO2 pattern.