JPH01187827A - Forming method for resist pattern - Google Patents

Abstract

PURPOSE:To form a desired semiconductor layer with good controllability by radiating a charged particle beam into an atmosphere containing material gas thereby to form a resist pattern, and then so etching as to selectively remove the pattern. CONSTITUTION:A substrate 1 is disposed on a susceptor 3, and electron beams 7 are radiated from two directions to the substrate 1 while supplying material gas 4 such as, for example, alkylnaphthalene gas to a sample chamber 5 thereby to deposit a resist, thereby forming a resist pattern 8. In case of the radiation, the beam 7 is inclined or the substrate 1 is inclined to differentiate the direction of the beam 7, thereby performing twice the similar radiation. The formed pattern 8 is widened from its lower part 8a to its upper part 8b. Then, with the pattern 8 as a mask A Schottky metal is selectively removed by wet etching, thereby forming a gate electrode 15.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for forming a resist pattern.

[Summary of the invention]

The present invention is a method for forming a resist pattern, in which a resist pattern is formed by irradiating a charged particle beam in an atmosphere containing a source gas.
After a resist pattern is formed, a semiconductor layer having a desired shape can be formed with good controllability by, for example, lift-off by selectively etching the resist pattern.

[Conventional technology]

In recent years, in photolithography for forming fine structures of semiconductor devices, a method has been adopted in which a resist is formed into a desired pattern using an electron beam instead of conventional light. That is, according to this method, after a negative resist layer is formed on the entire surface of the layer to be etched, only the portions of the etching layer that are to be left are selectively irradiated with an electron beam to harden them, and then developed to remove the unexposed portions. A resist pattern is formed by removing a portion of the resist. Furthermore, when a positive resist is used, only the portion of the resist layer to be removed is selectively irradiated with an electron beam to be solubilized, and then developed to form a desired resist pattern. However, according to photolithography using this electron beam,
Since three steps are required: a resist coating step, an electron beam irradiation step, and a development step, there are problems in that the manufacturing method is complicated and the yield is reduced. Therefore, as a method that can solve such problems, for example, the substrate (
A method has been proposed in which a desired resist pattern is formed by depositing a resist by irradiating an electron beam along a desired pattern onto the etched layer (see Japanese Patent Application No. 62-299405).

[Problem to be solved by the invention]

When attempting to form a desired resist pattern by depositing a resist by irradiating an electron beam in an atmosphere containing the above-mentioned source gas, and using this resist pattern to form a desired semiconductor layer by lift-off, Although the resist pattern must be removed with good controllability, there has been no suitable etching method for this purpose.

The present invention provides a resist pattern forming method that can solve the above problems.

[Means to solve the problem]

The method for forming the resist pattern (8) according to the present invention is to irradiate the layer to be etched (2) with a charged particle beam (7) in a desired pattern in an atmosphere containing source gas.
A step of depositing resist along this pattern to form a resist pattern (8);
8) as a mask to etch the layer to be etched (2), and a step of etching under conditions in which the resist pattern (8) is selectively etched.

Selective etching of the resist pattern (8), that is, isotropic etching, is performed under pressure > (3X 10/L) Pa
, and by performing reactive ion etching under the conditions of power > Q and 3 W/eII. However, L is the distance between the electrodes.

[For production]

A third example shows a case where a resist pattern (8) as shown in FIG. 4 is formed according to the means for solving the problem, and then isotropic etching is performed on the resist pattern (8) under the above conditions. As shown in the figure.

In the reactive ion etching apparatus used in this example, the area of the opposing electrodes was 300 cd, and the distance between the electrodes was lQc+m. Then, 5CC% of CFa (CCIlzFx etc. can also be used) is added to this device.
Etching was performed by enclosing 45 cc of ``e'' for lowering the degree of vacuum and scattering electrons, and applying a power of 300 W. That is, in this case, the pressure is 9 Pa and the power density is IW/c+J. In addition, if this pressure is rewritten into a general formula that does not depend on the device, it becomes 9 XIO (am
) / L (cm) Pa. L is the distance between the electrodes. When reactive ion etching is performed on the resist pattern (8) under these conditions, the height H (song!!A) is
At the same time, the width W (curve B) also decreases significantly over time, indicating that the etching is isotropic.

〔Example〕

An embodiment in which the present invention is applied to the manufacture of a Shontokey barrier type FET will be described.

First, as shown in FIG. 1A, a Schottky metal N is deposited on the entire surface of a GaAs substrate (11).
(2) is formed.

Next, as shown in FIG. 1B, this substrate (11) is placed on a susceptor (3) in an apparatus for forming a resist pattern (see FIG. 2), and a raw material gas (4) such as an alkyl By irradiating the substrate +11 with electron beams (7) from two directions while supplying naphthalene gas to the sample chamber (5), a resist is deposited and a resist pattern (8) is formed. , By tilting the electron beam (7) or by tilting the substrate (11), the same beam irradiation is performed twice with different irradiation directions of the electron beam (7).As shown in the figure, the resist pattern after formation is (8) is wider at the upper part (8b) than at the lower part (8a).

In Figure 2, (9) is the electron beam irradiation system, α[ is the converging lens, αυ is the exhaust system of the chamber sub-chamber, and α1 is the sample chamber (
In the exhaust system 5), the zero line is the supply pipe for the raw material gas (4).

Next, as shown in FIG. 1C, this resist pattern (8
) by performing wet etching as a mask to selectively remove the Schottky metal and form the gate electrode α.
form one.

Next, as shown in the first diagram, an ohmic metal layer OQ is formed by vapor-depositing an ohmic metal over the entire surface, thereby forming a source electrode αη and a drain electrode α.

Next, as shown in FIG. 1E, this substrate (1) is placed in a reactive ion etching device (not shown), and 5 cc of CF and 45 cc of He are sealed in this, and the area is 300 cc.
By etching the resist pattern (8) by applying 300 W between the opposing electrodes (distance: 10 mm), the resist pattern (8) and the ohmic metal 1101 on it are removed, resulting in a gate length of several hundreds. A human-sized Schottky barrier type GaAs FET Qω is obtained. That is, in this case, the resist pattern (8) was subjected to reactive ion etching under the conditions of a pressure of 9 Pa and a power density of IW/-.

In addition, in the above embodiment, the present invention is applied to a Schottky barrier type FE.
Although the description has been made for the case of manufacturing T, the present invention can be similarly applied to the case of manufacturing other semiconductor devices.

〔Effect of the invention〕

According to the present invention, after a resist pattern is formed by irradiating a charged particle beam in an atmosphere containing source gas, etching can be performed so that the resist pattern is selectively removed. It becomes possible to form a desired semiconductor layer with good controllability.

[Brief explanation of the drawing]

Fig. 1 is a process diagram of an example, Fig. 2 is a configuration diagram of an apparatus used in the present invention, and Fig. 3 is an isotropic process. FIG. 4 is a graph showing the tinging, and is a cross-sectional view of the resist pattern. fil is a GaAs substrate, (2) is a Schottky metal layer, (4) is a source gas, (7) is an electron beam, and (8) is a resist pattern. 7--＼ l 7 electric) beam,
7() ＼ Figure 1: 1 Sword Process Diagram `` Figure 1 Present Invention 1 Near;,・t12 flight m1 immersion structure diagram 4-v
A to τ1 Etsutenda time? 'Jl (min) Graph showing 1 tsunang of stem orientation

Claims (1)

[Claims] A step of forming a resist pattern by depositing a resist along the pattern by irradiating the layer to be etched with a charged particle beam in a desired pattern in an atmosphere containing source gas; A method for forming a resist pattern, comprising: etching the layer to be etched using the resist pattern as a mask; and etching under conditions where the resist pattern is selectively etched.