JPH0210357A - Fine pattern forming material and method therefor - Google Patents

Abstract

PURPOSE:To make possible to exactly form the fine pattern having a vertical section of the title material, without generating the charge up phenomenon of the material by incorporating a specified inorg. polymer compd. in the pattern forming material. CONSTITUTION:A polyphosphagen inorg. compd. shown by formula I is incorporated in the pattern forming material. In the formula, R1 and R2 are each a fluorine contg. alkyl or alkyl group, etc., (n) is a positive integer. The compd. shown by the formula is composed of a compd. shown by formula II, etc. An org. polymer film 11 as an under layer film, a film 12 composed of a compd. shown by the formula, and a film 13 composed of poly methyl methacrylate, etc., are applied on a semiconductor substrate 1, in this order, and then, the obtd. substrate is selectively exposed with electron beams 14, followed by developing the obtd. substrate to form a resist pattern 15. Subsequently, the film 12 is dry-etched using the resist pattern 15 as a mask, and the film 11 is etched to form a fine resist pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fine pattern forming material used in patterning and fabricating semiconductor elements and integrated circuits using electron beams, and a fine pattern forming material using the same material. This relates to a forming method.

2. Description of the Related Art Conventionally, in the manufacture of ICs, LSIs, etc., patterns have been formed by photolithography using ultraviolet rays. With the miniaturization of elements, higher NA of stepper lenses and the use of shorter wavelength light sources are being promoted, but this has the disadvantage that the depth of focus becomes shallower. Furthermore, with the miniaturization of pattern dimensions of LSI elements, the manufacture of ASICs, etc., electron beam lithography has come to be used. Electron beam lithography has drawbacks such as poor dry etching resistance of the electron beam resist, deterioration of pattern accuracy due to the proximity effect of forward scattering and back scattering of electrons, and charge-up due to exposed electrons. In order to overcome these drawbacks, a multilayer resist process in which the functions of the resist are divided into a photosensitive layer and a planarization layer is an effective method. FIG. 3 is a diagram illustrating a multilayer resist process in electron beam lithography.

In order to suppress the proximity effect, an organic film with a thickness of 2 to 3 μm is applied as the lower layer 21, and an inorganic film such as Si02 or 5OG (spin-on glass) is applied as the intermediate layer 22.
An electron beam resist 23 is applied to the upper layer, and an aluminum layer 24 of approximately 100 layers is placed on top of this to prevent charge-up (FIG. 3(a)). After exposure, the aluminum layer is removed with an alkaline aqueous solution, and then developed (see FIG. 3). Next, the intermediate layer 22 is dry-etched using this resist pattern as a mask (FIG. 3(C)), and then the lower film 21 is dry-etched using the intermediate layer 22 as a mask (FIG. 3(d)). .

By using the multilayer resist process as described above, fine patterns can be formed with a high aspect ratio. However, a multilayer resist in which an aluminum layer or an 8102 layer is vapor-deposited is not practical because the process is more complicated and there are problems such as contamination.

Among electron beam resists, polymethyl methacrylate) (
PMMA) is known to have the best resolution, but its drawback is low sensitivity.

Therefore, in recent years, many reports have been made to improve the sensitivity of positive electron beam resists. Positive electron beam resists have been published, such as a copolymer of methyl methacrylate and isobutylene, polybutene-1-sulfone, polyisopropenyl ketone, and fluorine-containing polymethacrylate. All of these resists are 1. This is a resist whose main chain is easily cleaved by an electron beam by introducing an electron-withdrawing group into the side chain or a degradable bond into the main chain, and is aimed at high sensitivity. However, there are problems such as poor dry etch resistance and charge-up effects due to insulation.

In addition, polysiloxane and polysilsesquioxane resists are available as resists for double-layer resists with high dry etch resistance (1/'>), but they do not have sufficient sensitivity or resolution.
Additionally, there is the problem of light influence due to charge-up due to insulation.

Problems to be Solved by the Invention As mentioned above, the multilayer resist process with an aluminum layer is an effective method, but there are problems such as complicated steps and aluminum contamination. Furthermore, a multilayer resist process in which the aluminum layer is removed has the problem of charge-up. Charge-up is a phenomenon in which exposed electrons accumulate in the resist, intermediate layer, or underlying layer, which is an insulator.

This charge-up effect causes major problems in electron beam lithography, such as field putting and deterioration of alignment accuracy. Furthermore, this charge-up phenomenon is also observed in single-layer resists, leading to deterioration in field putting and alignment accuracy, as in the case of three-layer resists.

That is, in electron beam lithography, exposed electrons scatter through the resist without losing energy and stop at a depth of 1-1.5 μm from the resist surface, and charges accumulate in that region.

This accumulated charge bends the electron beam,
It was thought that this would cause a deterioration in field putting and alignment accuracy.

Furthermore, conventional resists for two-layer resins have insufficient sensitivity and resolution, and because they are insulating films, they have the problem of causing charge-up.

In order to solve these problems, the present inventors used conductive inorganic polymers as electron beam resists and completed a method for forming fine patterns using them.

A means for solving the problem, that is, the present invention, (wherein R1 and R2 are the same or different fluorine-containing alkyl groups, an alkyl group, or an alkoxy group, and n is a positive integer) It is an attempt to solve the above-mentioned problems by using a polyphosphazene-based conductive inorganic polymer represented by .) as an electron beam resist. This polymeric material has a conjugated double bond in its main chain, exhibits high electrical conductivity, and can prevent charge-up due to electrons. Furthermore, by introducing fluorine into the side chain, it can be used as a highly sensitive positive resist. Furthermore, since the main chain is composed only of P and N, it has high dry etch resistance and can be used as an upper layer resist of a two-layer resist.

In addition, even if it does not act as a resist, by using this conductive inorganic polymer as an intermediate layer of a three-layer resist, a multilayer resist can be easily formed, and field batting collisions caused by charge up can be easily formed. −
, it is possible to form an accurate fine resist pattern without misalignment.

Function The present invention provides the above-mentioned conductive inorganic polymer resist, and
A resist process using this allows formation of accurate fine patterns that do not easily cause charge-up. There is no need to deposit an aluminum layer, there is no problem of contamination, the process can be simplified, charge-up by electrons can be prevented, and accurate fine patterns can be formed. Therefore, by using the present invention, it is possible to effectively form accurate, high-resolution fine patterns.

Examples Example 1 The polyphosphazene shown above was dissolved in chlorobenzene, and the insoluble matter was filtered off to obtain a resist solution. This resist solution was dropped onto the semiconductor substrate, and
Spin coat at 2°C.

Baking was performed for 30 minutes to form a resist film with a thickness of 1.2 μm. Acceleration WE2oKv,
After performing electron beam exposure at a dose of 1×10 C/d,
When development was performed with a mixed solution of methyl isobutyl ketone (MIBK) and isopropyl alcohol (IPA), an accurate resist pattern without field or batting errors due to charge-up could be obtained.

(Example 2) A second example of the present invention is shown in FIG. A polymeric organic film 2 is coated as a lower layer film on a semiconductor substrate 1, and heated at 220°C.
Baking was performed for 30 minutes. On top of this, the polyphosphazene inorganic film 3 obtained in Example 1 was applied and heated to 200°C.
After baking for 20 minutes, an inorganic film having a thickness of 0.6 μm was obtained (see FIG. 1(&)). Second, acceleration tE 20
When electron beam exposure was performed at KV, irradiation dose 1x 1o-5C/cd, and development was performed with a mixed solution of MI BK and IPA, an accurate fine resist pattern was obtained (Figure 1 (b)).
. charge up nyorfield batting
I couldn't see any errors. Using this resist pattern as a mask, the underlying polymeric organic film was etched to form an accurate and vertical fine resist pattern (FIG. 1(C)).

(Example 3) A third example of the present invention is shown in FIG. A polymeric organic film 11 is coated as a lower layer film on a semiconductor substrate 1, and heated at 2oO°C.
Baking was performed for 30 minutes.

A polyphosphazene inorganic film 12 shown below was applied thereon and baked at 20° C. for 20 minutes.

Further, pMMA was coated on this as an electron beam resist 13, and baked at 100° C. for 20 minutes (
Figure 2(a)). An accelerating voltage of 20 Kv was applied to this resist film.
Electron beam exposure was performed at a dose of 1×1O-4C/cd, and M
When development was performed with a mixed solution of IBK and IPA, an accurate fine resist pattern without field putting errors due to charge-up could be formed (FIG. 2, 03)). Dry etching of the inorganic film 12 is performed using this resist pattern as a mask (Fig. 2 (C)
)) Next, the polymer film 11 was etched using the inorganic film as a mask (FIG. 2(d)). In this way, an accurate and vertical fine resist pattern could be obtained.

As described in detail, according to the present invention, a resist pattern with high sensitivity and high resolution can be formed by using a polyphosphazene polymer, which is a conductive inorganic polymer, as an electron beam resist. . By using these resists, the influence of charge-up due to exposure electrons can be eliminated, and field batting and alignment accuracy can be improved. Also. Since the dry etch resistance is sufficiently high, it can be used as an upper layer resist of a two-layer resist.

In addition, by coating it as an intermediate layer in a three-layer resist, charge-up can be easily prevented and accurate and vertical fine resist patterns can be formed, greatly contributing to the production of ultra-high-density integrated circuits. can do.

[Brief explanation of the drawing]

FIG. 1 is a process sectional view of an embodiment of the present invention, FIG. 2 is a process sectional view of the same embodiment, and FIG. 3 is a process sectional view of a conventional multilayer resist method. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 11... Polymer organic film, 12... Inorganic film, 13... Electron beam resist. Name of agent: Patent attorney Toshio Nakao and one other person Figure 2

Claims (2)

[Claims] (1) General formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1 and R_2 represent the same or different fluorine-containing alkyl groups, and n represents a positive integer.) Polyphosphazene represented by A fine pattern forming material characterized by being made of a type of inorganic polymer. (2) After coating and heat-treating a polymeric organic film on a semiconductor substrate, a general formula: ▲Mathematical formula, chemical formula, table, etc.▼ (However, R_1 and R_2 are the same or different. represents an alkyl group or an alkoxy group, and n represents a positive integer.
It is characterized by comprising a step of heat treatment, a step of applying a resist on the inorganic polymer film, and a step of developing after drawing the pattern and etching the inorganic polymer film and the polymer organic film using the resist pattern as a mask. A method for forming fine patterns.