JPH0521325A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To simplify an etching process and to enable wiring formation of a contact hole at a low cost by carrying out exposure twice at an exposure amount whose sensitivity is lower than that of a charged particle beam sensitive resist and at a variable formation charged particle beam of large beam edge slope. CONSTITUTION:A positive type electron beam sensitive resist film 3 is applied onto an insulating film 2. The first exposure is carried out by using a first variable formation electron beam of large beam edge slope and an exposure part 8 is formed. An exposure amount in the process is half the sensitivity of the electron beam sensitive resist film 3. Then, the second exposure is carried out by using a second variable formation electron beam of large beam edge slope and an exposure part 9 is formed. An exposure amount in the process is half the sensitivity of the electron beam sensitive resist film 3. The electron beam sensitive resist film 3 is developed, an opening part 10 is formed, a tapered contact hole 7 is formed by etching and good coverage of a wiring material is realized.

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 a resist pattern, and more particularly to a method for forming a resist pattern used as an etching mask for contact holes.

[0002]

2. Description of the Related Art As a conventional method for forming a contact hole in a semiconductor device, a method as shown in process sectional views of FIGS. That is, in this conventional method, first, as shown in FIG. 11, the charged particle beam sensitive resist film 3 formed on the surface of the insulating film 2 covering the semiconductor substrate 1 is patterned to form a contact hole pattern 4. To do. Then, isotropic wet etching is performed through the contact hole pattern 4 to side-etch the upper portion of the insulating film 2 to form a recess 5 as shown in FIG.

Then, anisotropic dry etching is performed through the contact hole pattern 4 to form the recesses 5.
In the lower insulating film 2, a recess 6 having a width substantially the same as that of the contact hole pattern 4 as shown in FIG. 13 is formed.

After that, if the charged particle beam sensitive resist film 3 is removed, a tapered contact hole 7 as shown in FIG. 14 can be formed. The use of the tapered contact hole 7 improves the coverage of the wiring material formed on the contact hole 7 and ensures sufficient electrical continuity with the base.

[0005]

However, in the conventional example as described above, anisotropic dry etching must be performed after isotropic wet etching, and the process becomes complicated. Have

In view of the above points, the present invention has an object to provide a method for forming a resist pattern which simplifies the etching process and enables formation of contact hole wiring at low cost.

[0007]

In order to solve the above problems, a method of forming a resist pattern according to the present invention is a variable shaped charging with an exposure amount lower than the sensitivity of a charged particle beam sensitive resist and a large beam edge slope. The first exposure is performed with a particle beam, and then the exposure is such that the width is narrower than the first pattern and the sum of the first exposure and the first exposure is equal to the sensitivity of the charged particle beam sensitive resist. The second exposure is performed with a variable shaped charged particle beam having a large edge slope.

[0008]

According to the present invention, since the exposure amount reaches the sensitivity of the resist in the central region of the exposed portion of the charged particle beam sensitive resist film by the above-mentioned constitution, the development reaches the bottom portion of the charged particle beam sensitive resist film. An opening is formed up to.
On the other hand, in the peripheral portion of the exposed portion of the charged particle beam sensitive resist film, since the exposure amount does not reach the sensitivity of the resist, only the surface near the surface of the charged particle beam sensitive resist film is opened by developing. Further, since the edge slope of the variable shaped charged particle beam is large, the sectional shape of the charged particle beam sensitive resist film after development is tapered. When the underlying insulating film is dry-etched using such a charged particle beam sensitive resist film as a mask, a contact hole having a tapered shape with a two-step structure can be formed, and the coverage of the wiring material becomes good. Further, the etching process can be simplified because it is one process.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a resist pattern in an embodiment of the present invention will be described in detail below with reference to the drawings.

1 to 8 are sectional views showing steps of a method of forming a resist pattern according to an embodiment of the present invention. In FIG. 1, 1 is a silicon substrate as a semiconductor substrate and 2 is a 1.0 μm thick SiO ₂ film 2 as an insulating film.

In this embodiment, first, as shown in FIG. 1A, a positive type electron beam sensitive resist film 3 having a thickness of 1.2 μm is applied on the SiO ₂ film 2.

Next, as shown in the electron beam intensity profile of FIG. 10, the first exposure is performed using the variable shaped electron beam having the first large beam edge slope, and the first exposure as shown in FIG. The portion 8 is formed in the electron beam sensitive resist film 3. The exposure amount in the first exposure is half the sensitivity of the electron beam sensitive resist film 3.

Next, as shown in the electron beam intensity profile of FIG. 10, the second exposure is performed using the variable shaped electron beam having the second large beam edge slope, and FIG.
As shown in FIG. 3, a second exposed portion 9 having a width narrower than that of the first exposed portion 8 is formed on the electron beam sensitive resist film 3. The sum of the exposure amount in the second exposure and the exposure amount in the first exposure is the sensitivity of the electron beam sensitive resist film 3. That is, in this embodiment, the sensitivity is half the sensitivity of the electron beam sensitive resist film 3.

Next, the electron beam sensitive resist film 3 is developed to form an opening 10 as shown in FIG. At this time, since the first and second exposures are performed using the variable shaped electron beam having a large beam edge slope, a tapered cross-sectional shape of the electron beam sensitive resist film 3 is obtained.

When dry etching is performed using the resist pattern thus formed as a mask, the electron beam sensitive resist film 3 is also etched, and the tapered shape as shown in FIG. 7 is obtained as shown in FIGS. The contact hole 7 is formed in the SiO ₂ film 2.

Next, after removing the electron beam sensitive resist film 3, aluminum 11 is deposited and patterned as a wiring material to form wiring on the contact hole 7 and the SiO ₂ film 2 as shown in FIG. be able to.

In this embodiment, the electron beam exposure is used for description, but charged particle beam exposure such as ion beam exposure may be used.

[0018]

As described above, according to the present invention, the exposure is performed with the first variable shaped charged particle beam having the exposure amount lower than the sensitivity of the charged particle beam sensitive resist and the large beam edge slope, and then the first variable shaped charged particle beam is used. The second variable shaped charged particle beam is narrower than the pattern No. 1 and has an exposure amount whose sum with the first exposure amount is equal to the sensitivity of the charged particle beam sensitive resist and has a large beam edge slope. As a result, a contact hole resist pattern having a two-step tapered shape can be formed. Further, if the insulating film is dry-etched using this resist pattern as a mask, a contact hole having a tapered shape with a two-step structure can be formed, the coverage of the wiring material is improved, and the etching step is simplified to one step. be able to.

[Brief description of drawings]

FIG. 1 is a process sectional view of a method for forming a resist pattern according to an embodiment of the present invention.

FIG. 2 is a process sectional view of a method for forming a resist pattern according to an embodiment of the present invention.

FIG. 3 is a process sectional view of a method for forming a resist pattern in an example of the present invention.

FIG. 4 is a process sectional view of a method for forming a resist pattern in an example of the present invention.

FIG. 5 is a process sectional view of a method for forming a resist pattern in an example of the present invention.

FIG. 6 is a process cross-sectional view of a method for forming a resist pattern in an example of the present invention.

FIG. 7 is a process cross-sectional view of a method for forming a resist pattern according to an example of the present invention.

FIG. 8 is a process sectional view of a method for forming a resist pattern in an example of the present invention.

FIG. 9 is a diagram showing an electron beam intensity profile in a conventional example.

FIG. 10 is a diagram showing an electron beam intensity profile in an electronic example of the present invention.

FIG. 11 is a process sectional view showing a conventional example.

FIG. 12 is a process sectional view showing a conventional example.

FIG. 13 is a process sectional view showing a conventional example.

FIG. 14 is a process sectional view showing a conventional example.

[Explanation of symbols]

1 Silicon substrate as a semiconductor substrate 2 SiO2 film as insulating film 3 Electron beam sensitive resist film 7 contact holes

Claims (2)

[Claims] 1. A variable shaped charged particle beam is used to apply a charged particle beam sensitive resist on a semiconductor substrate, and a first exposure is performed with an exposure amount lower than the sensitivity of the charged particle beam sensitive resist.
Exposure of the second pattern having a width smaller than that of the first pattern, and the sum of the exposure amounts of the second shot and the first shot is equal to the sensitivity of the charged particle beam sensitive resist. A method for forming a resist pattern, which comprises exposing with a light. 2. When exposing the first and second patterns, the shots forming the first and second patterns are exposed by increasing the beam edge slope of the shots. Method of forming resist pattern of.