JPH0282535A - Manufacture of electrode for transistor gate - Google Patents

Abstract

PURPOSE:To form simultaneously a thin gate electrode part and a rather thick gate electrode pattern part by forming a thin slit pattern on the first substance and etching a substrate to the prescribed amount to produce a recessed part after removing the second substance, thereby performing a lift-off process after depositing a substance to form a gate electrode. CONSTITUTION:After patterning the first substance (deposited SiO2 film 24 and resist 23) only to a part corresponding to a channel, a resist is applied. Patterning of a gate part (a) is performed on the first substance and patterning of a gate pad part (b) located on a gate pad is performed on a part that is lacking in the first substance. Then the second substance (Al film 27) is subjected to vacuum deposition at an angle that is tilted from verticality with respect to the substrate 21 and the first substance is treated with anisotropic dry etching by using the second substance as a mask and then, a thin slit pattern of the first substance is formed. Subsequently, the substrate 21 is etched to the prescribed amount to produce a recessed part after removing the second substance and a lift-off process is performed after depositing a substance to form a gate electrode. In this way, a thin gate electrode part 28 and a gate pad part 29 to form a thick gate electrode pad are formed simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of manufacturing a gate electrode of a transistor, and particularly relates to a method of forming an extremely short gate electrode of a microwave band transistor using a compound semiconductor or the like. It is something.

(Prior Art) Conventionally, there have been technologies in this field, such as those shown below.

The configuration will be explained below using figures.

FIG. 2 is a sectional view of the manufacturing process of the gate electrode of such a conventional transistor, and particularly shows the process of forming an extremely short gate electrode of a microwave band transistor.

First, a resist 2 is applied onto a base (semi-insulating gallium arsenide substrate) 1, and a substance 3 is formed thereon by a vacuum evaporation method or the like. As the substance 3, a dry-etchable metal or the like is often used. Next, after applying resist 4,
A fine pattern is formed by an electron beam exposure method or the like [see FIG. 2(a)].

Next, the material 3 is processed by dry etching using this resist pattern as a mask [see FIG. 2(b)].

Next, 0. The resist 2 is etched by dry etching. At this time, the resist 4 is etched at the same time (see FIG. 2(c)).

Next, the substrate 1 is recessed by a predetermined amount using the two-layer material pattern consisting of the material 3 and the resist 2 as a mask [see FIG. 2(d)].

Next, a fine pattern of metal 5 is formed on the recess-etched substrate l by vapor deposition and lift-off.
See figure (e)].

(Problem H to be solved by the invention) However, according to the above-mentioned prior art, not only is an expensive device such as an electron beam exposure device required, but even if such an electron beam exposure device is used, .1 μm
It takes a very long time to draw such a fine pattern that it is impractical.

Furthermore, it is more difficult to form not only fine patterns but also thicker patterns such as pads at the same time.

The main object of the present invention is to provide a method for manufacturing a transistor gate electrode that employs a conventionally commonly used light exposure method and that can efficiently form a fine metal pattern of about 0.1 μm. It is to be.

A further object of the present invention is to provide a method for manufacturing a transistor gate electrode, in which not only fine patterns but also thicker patterns such as pads can be simultaneously formed in a method for forming fine metal patterns. .

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a gate electrode of a transistor provided on a substrate. after patterning the material, applying a resist, patterning a gate on the first material, and patterning a portion corresponding to a gate pad on a portion without the first material; A second material is vacuum-deposited from an angle tilted from perpendicular to the plane, and the first material is processed by anisotropic dry etching using the second material as a mask to form a thin slit pattern in the first material. and (c) after removing the second material, recess-etching the base by a predetermined amount, and depositing and lifting off a material that will become the gate electrode, thereby forming a thin gate electrode part and a thinner gate electrode part. This method includes a step of simultaneously forming a portion that will become a thick gate electrode pattern.

(Function) According to the present invention, as shown in FIG. 1, in the step of forming the gate electrode of the transistor on the substrate 21, the first material [evaporated in FIG. After patterning [5ift film 24 and resist 23], a resist is applied, and the gate part a is patterned on the first material, and the gate pad part on the gate pad is patterned on the part where there is no first material. Perform patterning [see FIG. 1(d) 30] Next, a second material [An film 27 in FIG. 1(e)] is vacuum-deposited at an angle inclined from perpendicular to the substrate 21 [see FIG. 1(d)]. See (e)]
Using the second material as a mask, the first material is processed by anisotropic dry etching to form a fine slit pattern of the first material [see FIG. 1(f)].

Next, the second material is removed and the base 21 is recess-etched by a predetermined amount (see FIG. 1(g)), and a material that will become the gate electrode is evaporated and lifted off (see FIG. 1(h)).
)], for fine gates! The pole portion 28 and the gate pad portion 29, which becomes a thicker gate electrode pad, can be formed at the same time.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of the manufacturing process of a gate electrode of a transistor showing an embodiment of the present invention.

First, a SiN film 22 is deposited on a substrate (semi-insulating gallium arsenide substrate) 21 by plasma chemical vapor deposition.
Next, a resist 23 is applied, and a film 24 of evaporated Sin is deposited by a vacuum evaporation method (see FIG. 1(a)).

Next, after forming a resist 25, patterning is performed [
See Figure 1(b)].

Next, reactive ion etching (RIIE)! Using a sulfur hexafluoride gas 111H, the deposited sio, I] 124 and the resist 23 are sequentially etched away using a sulfur hexafluoride gas 111H and a resist 23 deposited with OfIIIE. In this case, the resist 25 is completely removed by etching the resist 23 [see FIG. 1(c)].

Next, after forming the resist 26, the resist 26 is patterned so that a slit having an inversely tapered shape is formed. As a result, a gate portion a of the field effect transistor is formed on the left side, and a gate pad portion for wiring the gate is formed on the right side. Furthermore, using the resist 26 as a mask, the SiN film 22 on the gate pad portion is removed by etching with sulfur hexafluoride gas RIB [see FIG. 1(d)].
At this time, the thicknesses of the vapor-deposited SiO□ film 24 and the SiN film 22 are selected such that the vapor-deposited SiOzM424 on the gate portion a is hardly etched, and the etching selectivity of 5t (h and SiN) is selected. Choose etching conditions that will give you a large amount of .

Next, AI! from a direction that makes an angle of θ with the vertical direction! .

A film 27 is deposited [see FIG. 1(e)].

Next, sulfur hexafluoride gas RIB was used to deposit 540°8
24, the resist 23 by 0□ RIE, and the SiN film 22 by sulfur hexafluoride gas R1E (see FIG. 1(f)).

Next, after removing the 172 film 27 by wet etching, the base 21 is recessed by a predetermined amount [see FIG. 1(g)].

Next, on the recess-etched base 21, a gate electrode for the transistor is formed! The electrode 2829 is formed by vapor deposition and lift-off [see FIG. 1(h)].

In addition, in the above process, the SiNM2 shown in FIG. 1(f)
2 RIE and subsequent etching of the film 27 are as follows:
It is also possible to change the order. In addition, evaporated SiO
The □ film 24 may be 5iOzll formed by another method, such as sputtering, or may be any other material as long as it satisfies the etching selectivity described above.

Furthermore, the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, the following effects can be achieved.

(1) A thin gate electrode of about 0.1 μm, which is quite difficult to form even with an electron beam exposure device, can be formed relatively easily.

(2) It does not require expensive equipment such as electron beam exposure equipment, and pattern formation does not require much time.
Excellent for mass production.

(3) Since the gate length is determined only by the angle of oblique evaporation of 111g as a mask material and the thickness of the resist having an inversely tapered shape, a highly accurate gate length can be achieved.

(4) Since a very fine metal pattern and a wider pattern such as a pad can be formed at the same time, it is particularly practical for forming gate electrodes of field effect transistors.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the manufacturing process of a gate electrode of a transistor showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the manufacturing process of a conventional gate electrode of a transistor. 21...Substrate, 22...SiN II! , 23.2
5.26...Resist, 24...Vapour-deposited Si0g film,
27...An film, 28. 29...2 electrodes (transistor gate electrode). Patent applicant Oki Electric Industry Co., Ltd. Agent Patent attorney Mamoru Shimizu (1 other person) Fig.

Claims (1)

[Claims] In a method for manufacturing a gate electrode of a transistor provided on a substrate, (a) after patterning a first material only in a portion corresponding to a channel on the substrate, applying a resist; (b) vacuum evaporation of a second material from an angle inclined from perpendicular to the substrate; The first material is processed by anisotropic dry etching using the second material as a mask.
(c) After removing the second material, recess-etching the substrate by a predetermined amount and depositing a material that will become the gate electrode.
By lifting off, the thin gate electrode part and
A method for manufacturing a gate electrode for a transistor, which method includes the step of simultaneously forming a portion that will become a thicker gate electrode pattern.