JPH01140729A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor device of an extremely fine structure by a method wherein a layer of a second substance is formed so as to cover a mask pattern composed of a first substance and a third substance is formed on a substrate by making use of the second substance as a mask. CONSTITUTION:While a substrate 51 is irradiated with a charged particle beam by a required pattern in an atmosphere containing a raw material gas, a mask pattern 52 composed of a first substance as a product from the raw material gas along the pattern is formed. Then, after a layer 53 of a second substance has been formed so as to cover the mask pattern 52, the first substance of the mask pattern 52 is removed selectively. Then, a third substance 53 is formed on the substrate 51 by making use of the layer 53 of the second substance as a mask. By this setup, it is made possible to form an extremely fine pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for forming fine patterns that is applied, for example, to the manufacture of semiconductor devices.

[Summary of the Invention] The present invention provides a method for forming a fine pattern by irradiating a substrate with a charged particle beam in a desired pattern in an atmosphere containing a source gas, thereby forming particles that are products of the source gas along the pattern. Forming a mask pattern made of one substance,
After forming a layer of a second material covering the mask pattern, selectively removing the first material of the mask pattern, and then forming a third material on the substrate using the layer of the second material as a mask, This makes it possible to form extremely fine patterns.

[Conventional technology]

Conventionally, when manufacturing fine structures such as large-scale integrated circuits (LSI), the so-called IJ soger beam technology using light has been mainly used.

However, manufacturing a fine structure the size of 200 people would be an order of magnitude too large even if far infrared rays were used, and it would be difficult even if X-rays were used. In other words, for example, to manufacture the fine structure of 200 people, a resolution lower than that is required, and the wavelength is 2
It is necessary that the thickness be 00 Å or less. This is the area of X-rays, and the current situation is that there are many problems that need to be solved for both the light source and the mask material.

On the other hand, patterning using an electron beam has recently begun to be used as an alternative method. Examples are shown in FIGS. 4 and 5.

Figure 4 shows the case where a positive resist is used, and the substrate (
1) Coat a positive resist (2) on top (see Figure 4C), and apply resist C2 by electron beam exposure (4) and development.
) patterning (see Figure 4C). Next, apply the pattern forming material (3) on the entire surface (see Figure 4C).
, the resist (2) is peeled off (lifted off) together with the pattern forming material (3) thereon to form a pattern forming material (3) in a predetermined pattern on the substrate (1) (see the fourth diagram).

Figure 5 shows the case where a negative resist is used, and the substrate (
11) A pattern forming material (12) is formed on the pattern forming material (12), and a negative resist (13) is further deposited on the pattern forming material (13) (see FIG. 4C), and resist I-(13) is formed by electron beam exposure (14) and development. ) patterning (see Figure 4C). Next, using the resist (13) as a mask, pattern forming material I
t(12) is selectively etched to form a pattern forming material (1
2) is patterned (see FIG. 5C).

Peel off (13) (see diagram 5)
.

[Problem that the invention seeks to solve]

In the above-mentioned patterning method using electron beams, for both positive and negative resists, thousands of resists are applied in advance, and then the resist material is changed using electron beam exposure to obtain the desired pattern. . The starting material for forming a pattern, which is the ultimate goal in this case, is a solid resist, which acts as a multiple scatterer for the incident electron beam. At this time, for example, as shown by Mr. Wilkinson et al. (Superlattices and M.
icrostructures.

Vol. 2 No. 61986), Figures 6 and 7
An unusual trajectory of electrons is expected. Figure 6 shows a 0.3 μm thick L/
The trajectory of 100 scattered electrons after a 50KV electron beam (23) is incident on the cyst layer (22) is shown.
The figure shows the electron trajectory after a 1QkV electron beam (24) is incident on the same sample.

As can be seen from this figure, the original spatial resolution is lost while passing through the resist due to multiple scattering of electrons in the resist. This is especially fatal for negative resists. Additionally, because electrons are backscattered from the substrate, the electrons will also hit the resist elsewhere. The figure shows 81 substrate, but GaAs
This effect is magnified for substrates and the like. Therefore, the areas through which the electrons pass are exposed to light whether we like it or not, and all of these things hinder the production of ultrafine structures.

In addition, as a pattern forming method, a substrate is placed in an atmosphere exposed to a gas containing a constituent material such as a metal or semiconductor, and a desired portion of the surface of the substrate is irradiated with an electron beam to form a desired pattern of metal or semiconductor on the substrate. A method of depositing is known (see Japanese Patent Publication No. 62-42417). Another known method is to place a substrate in a gaseous resist atmosphere and deposit a desired pattern of resist by irradiating the substrate surface with an electron beam (Applied Physics Let
ters, Vol, 29. No, 919765
(See pages 96-598).

In view of the above-mentioned points, the present invention proposes a method for forming a fine pattern that makes it possible to manufacture a semiconductor device or the like having an extremely fine structure.

[Means for solving problems]

In the present invention, by irradiating the substrate (5I) with a charged particle beam (41) such as electrons, positrons, muons, etc. in a required pattern in an atmosphere containing the raw material gas, the raw material gas 37) is emitted along the pattern. Depositing a mask pattern (52) made of a first substance as a product, forming a layer (53) of a second substance covering the mask pattern (52), and forming the mask pattern (52). 1st
A method for forming a fine pattern, comprising the steps of selectively removing a substance, and forming a third substance 'It (55) on a substrate (51) using a second substance (53) as a mask. It is.

[Effect]

The mask pattern (52) made of the first material on the substrate is
It is formed by the product of the raw material gas 37) by irradiating the charged particle beam (41) onto the substrate in the raw material gas atmosphere. In particular, when the first material is a resist, since the starting material is a gas, there is no multiple scattering of electrons in the resist, and the substrate (51
), a mask pattern (52) with good resolution (fine) is formed.

By selecting the beam irradiation conditions, the mask pattern (52) is formed in such a shape that the film thickness becomes narrower upward from the bottom. Then, mask pattern (5
After forming a layer (53) of the second material covering 2),
By selectively removing the first material of the mask pattern, a cavity (54) having an opening in the second material B (53) and in which an eaves portion is formed is formed.

Next, the cavity (5) is formed using the second material layer (53) as a mask.
Since the third material (55) is formed on the substrate in 4), the pattern of this third material (55) is a mask pattern <52).
It becomes even finer than that.

Therefore, it becomes possible to form extremely fine patterns.

〔Example〕

Hereinafter, embodiments of the method for forming a fine pattern according to the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of the apparatus used in this embodiment.

In the figure, (31) is an electron beam irradiation system, (32)
is a sample chamber provided in the chamber (23), (34)
is a substrate serving as a sample placed on the susceptor (35) of the sample chamber (32). (38) is an exhaust system for the chamber (33), and (39) is an exhaust system for the sample chamber (32). The raw material gas (37
) will be introduced.

In this example, a gas containing a negative resist (hydrocarbon) as a constituent material, such as alkylnaphthalene, is used as a raw material gas (37
) and introduced into the sample chamber (32). The chamber (33) and sample chamber (32) are evacuated to a similar high vacuum. Alkylnaphthalene, the raw material gas, is liquid in the atmosphere, but gasifies in vacuum. In addition, this alkylnaphthalene does not interact with the substrate (22) in any way because it has a high vapor pressure or a small adhesion coefficient.The pressure of the raw material gas atmosphere in the sample chamber (22) is 1O-
5 Torr ~IQ-'Torr, typically 10-''
It is about Torr.

The substrate temperature is maintained at an appropriate temperature within the range of room temperature to about -30°C.

Then, for example, the electron beam (41) with an acceleration voltage of 5 kV and a beam current of 20 μ is focused by a converging lens (40) and irradiated for 5 seconds on a desired part of the substrate (34) in the raw material gas atmosphere. A resist is generated from the gas, and a resist film is deposited on the desired portion. As the resist film, a resist film having good acid resistance and RIE resistance and for selective epitaxial use is formed.

Here, the starting material for the resist is a solid (gas), so there is no multiple scattering in the resist, and recoil electrons due to backscatter from the substrate do not have as much of an adverse effect on solid resists, and the blur is not small. In terms of resolution, a so-called line and space (that is, the stripe width when forming a striped resist film and the space width between adjacent stripes, respectively) can be obtained up to about 250 degrees. , it is possible to obtain a resolution of 100 Å or less by optimizing the accelerating voltage of the electron beam (41).

The lower limit of this value is supported by the sum of the blurring of the electron beam (about 40 degrees) and the thick polymerization of the hydrocarbon film (about several dozen degrees). Then, as shown in Figure 3, an electron beam (4
1) by scanning a width of 10 on the surface of the substrate (34).
A resist pattern (42) of 08 or less is directly drawn.

Example 1 A case where the present invention is applied to manufacturing a Schottky barrier type FET will be described.

First, a semiconductor substrate (for example, a GaAs substrate <51) is placed in the apparatus shown in FIG. A resist film (52) is formed on the substrate (51).
) to form. At this time, if the adjustment of the electron beam (41) is optimized to increase the resolution and the electron beam irradiation time is lengthened, the width β of the main base becomes 10 as shown in Figure 1A.
A resist film (52) is formed having a thin serrated portion (52a) on the side of about 000 mm, and has a thickness d such that the width β decreases toward the side of about 4000 mm. .

Next, as shown in FIG. 1B, the film is trimmed by RIE (reactive ion etching) to remove the skirt portion (52a), so that the bottom width l is about 1000 A and the film thickness d2 is 3.
000 resist film (52).

Next, as shown in FIG. 1CI or FIG. 102, an ohmic metal (53) is deposited on the entire surface of the GaAs substrate (51) including the resist film (52).

Next, as shown in the first diagram, ohmic metal (53)
The entire surface of the resist film (52) is etched in the same direction until the upper part of the resist film (52) is partially exposed.

Next, only the resist film (52) is selectively removed by RIE or the like (FIG. 1E). A cavity (54) is formed by removing this resist film (52). The width W of the opening of the cavity (54) formed in this ohmic metal (53) is a fraction of the width β of the base, that is, about 200 degrees.

Next, as shown in Figure 1F, Schottky metal (55)
is deposited on the entire surface. This allows the source electrode (53S) and drain electrode (53P) to be made of ohmic metal.
A gate electrode (55G) made of Schottky metal with a width corresponding to the opening width W is formed on the surface of the GaAs substrate (51) between
is formed. In this way, a Schottky barrier type GaAs FET (56) with a source-drain spacing of less than 1000 Å and a gate length of approximately 200 nm is obtained.

Note that although the present invention is applied to the manufacture of a Schottky barrier type FET in the above example, it can also be applied to the manufacture of other semiconductor devices. or,
It is also possible to use other metals, semiconductors, insulators, etc. in place of ohmic metals and Schottky metals.

〔Effect of the invention〕

According to the present invention described above, a mask pattern of the first material is formed by irradiating the substrate surface with a charged particle reservoir in a source gas atmosphere, and after forming a second material layer covering this mask pattern, the mask pattern is is selectively removed and then the second
By using the material layer as a mask to form a third material on the substrate within the cavity from which the mask pattern has been removed, a third material layer having a very fine pattern can be formed. Therefore, this form is particularly suitable for use in the manufacturing process of semiconductor devices such as large-scale integrated circuits with extremely fine structures.

[Brief explanation of the drawing]

1A to 1F are process diagrams when the present invention is applied to manufacturing a Schottky barrier type FET, FIG. 2 is a block diagram of an apparatus applied to implement the present invention, and FIG. 3 is a diagram of the apparatus shown in FIG. 2. FIGS. 4A-D are process diagrams showing an example of pattern formation using a conventional positive resist, and FIGS. 5A-D are perspective views showing a state in which a mask pattern is formed on a substrate using FIGS. 6 and 7 are process diagrams showing an example of pattern formation using a conventional negative resist, and are diagrams showing the scattering state of electrons when a resist film is exposed to an electron beam, respectively. (31) is the electron beam irradiation system, (32) is the sample chamber, (3
4) is the substrate, (37) is the source gas, (51) is GaAs
The substrate (52) is a resist film, (53) is an ohmic metal, and (55) is a shot metal. The present invention/l Implementation 1: ll As・S device 4 Nose exhalation Figure 2 Honest and end 1 f'l 2 44 L 3 Ko 1 figure 3 Zuji (East fFIA Pattern Vinegar) Song and Gong 41 Figure 4 Figure 5 Procedural Amendment June 27, 1988 Patent Application No. 299405 2, Name of Invention Method for Forming Fine Patterns 3, Relationship with the case of the person making the amendment Patent applicant address No. 6-7-35, Kitashina-yo, Tokyo Parts-Yo-ku Name (2
18) Norio Ohga, Representative Director of Sony Corporation 4, Agent address: 1-8-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo. Location: 03-343-5821ff6 (Shintaku Hill) 6
, the number of inventions increased due to the amendment (in the 11th specification, the 3rd line from the bottom of the 8th line "highly or" was changed to "
Correct to "lower or". (2) Same, 3rd line to 2nd line from the bottom of the same page, change "coefficient is small" to "
The coefficient is large, however.'' (3) Same, page 9, line 13, “no multiple scattering” was changed to “
"There is no multiple scattering in principle." (4) Same page, line 14, ``Also from the substrate'' is corrected to ``Also, because of this, the beam does not spread at the substrate entrance, and from the substrate.'' (5) Same, same page, line 15, ``There is no adverse effect,'' is corrected to ``Because it will not spread.'' (6) Ibid., lines 15-16 of the same page, “not small” is replaced with “
"It's small," he corrected. that's all

Claims (1)

[Claims] By irradiating a substrate with a charged particle beam in a desired pattern in an atmosphere containing a source gas, a mask pattern made of a first substance, which is a product of the source gas, is deposited along the pattern. Step: forming a layer of a second material covering the mask pattern; selectively removing the first material forming the mask pattern; forming a third material on the substrate using the second material as a mask; A method for forming a fine pattern, which consists of the steps of: