JPH02133927A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an electrode whose width is narrower by a method wherein a first photoresist is formed on a substrate, a second photoresist is formed thereon, a first opening is formed in the second photoresist, the first photoresist is etched from the opening, a second taper-shaped opening which is widened with a distance from the substrate is formed and a metal film is formed on the substrate from the opening. CONSTITUTION:A first photoresist 2 is formed on a substrate 1; a second photoresist 3 is formed on the first photoresist 2. A first opening 4 is formed in the second photoresist 3 by using a deep UV light source. Then, the first photoresist 2 is etched by an ion beam using an Ar ion from a direction nearly perpendicular to the first photoresist 2 by making use of the second photoresist 3 as a mask; a second taper-shaped opening 5 is formed; thereby, a width, on the side of the substrate, of this hole becomes shorter than a width of the first hole 4. Then, the substrate 1 is wet-etched from the first opening 4; a recess part 6 is formed; in succession, a gate metal film 7 of Al or the like is deposited by evaporation by making use of the first photoresist 2 and the second photoresist 3 as a mask; a gate electrode 8 is formed by a lift-off method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming electrodes and wiring lines with fine line widths.

(b) Conventional technology Lift-off is a method for selectively forming electrodes and wiring in semiconductor devices. This method involves coating the entire surface of a substrate with a photoresist, selectively exposing the entire photoresist to light, developing it, and photoresist. By opening a resist, completely depositing an electrode material thereon, and removing the photoresist and the electrode material on the photoresist, the entire electrode is formed on the substrate using only the opening of one photoresist.

Generally, selective exposure of photoresist is performed using a mask. The minimum line width that can be realized by forming nine electrodes using a photoresist with holes opened by exposure to ultraviolet rays or deep ultraviolet rays as a mask is about 0.5 μm. This
The line below @? Examples of methods for obtaining the photoresist include exposure to X-rays, exposure to an excimer laser, or direct writing with a photoresist t-electron beam without using a mask.

However, in the case of X-ray exposure, it is difficult to manufacture a mask for X1m exposure, and many steps are required, resulting in high manufacturing costs.

In the case of excimer laser exposure, the exposure source is not suitable for use, etc.
Exposure equipment has not been established. Also, when drawing directly with an electron beam, the drawing time is very long, so the manufacturing efficiency is extremely low and it is not suitable for mass production. have. These technologies are 5solid 5tate
8chnology/Japanese version/August 1986
P52~59rHigh JGaAS FET microlithography technology" 0 Field effect transistor (FETJ, special [GaAs S 庖・Used white")
FETs based on Tokiat and HEMTs using high-mobility electrons accumulated at the heterojunction interface, especially GaAS/AjG
To aAS? IEMTs (with CI junctions) have high electron mobility and are therefore used as ultra-high frequency devices. FET
In order to improve the microwave characteristics of a HEMT or a HEMT (particularly to reduce the noise figure), a return wire of the gate length is necessary.

←1 Problems to be Solved by the Invention As mentioned above, although it is necessary to shorten the gate length in order to improve the microwave characteristics of FET, )lft:MT, the line M is not connected to the mask pattern. It was limited by the openings in the photoresist obtained by the transfer of the photoresist. Furthermore, the techniques for direct drawing using X-ray exposure, excimer laser exposure, or electron beams have not yet been established, and the productivity is poor, making them unsuitable for mass production.

The present invention is not limited to the conventional &I brocade obtained by transferring a master pattern to a photoresist by exposure using ultraviolet rays or deep ultraviolet rays, but aims to form electrodes with more narrow edges. It is.

1+1 Lesson Ut-Means for Solving the Problem The present invention includes a step of forming a first photoresist on a substrate, and a step of forming a first photoresist on a substrate, and
a step of forming a second photoresist on the FV cyst, a step of forming a first hole in the second photoresist, and a step of forming a first hole from the first hole. The method includes the steps of etching the photoresist to form a tapered second opening that widens as the amount of electricity is applied from the substrate, and forming gold IR@lr on the substrate from the second opening. As shown in FIG. Therefore, the incident angle of the first photoresist is 90 DI! After ILI, under appropriate conditions (such as setting the vacuum f' lower than normal), the ion beam etching causes diffuse reflection of the ions, forming a second tapered opening that widens as it gets farther away from the substrate. can (e.g. J, Vac, sci, 'rechni)
, , VOl, 12. NO, 1.

Jan, /Feb, 1975 P28-35 #sho)Q
If a metal film is deposited using this opening, a gate electrode can be formed from the first opening.

(F) Embodiment An embodiment of the present invention is shown in FIGS. And wavelength ~ 260 nm (7) Dee3 ptJ
0.5μ onto the second photoresist 13+ using a v light source.
Forming the first opening 141 (Fig. The entire opening can be formed only in the second photoresist 131.

The conditions for ion beam etching are gas flow @
o sc am, gas pressure crab (v4X10T.

rr, FIF'a force 3 (JOY, acceleration voltage 200v. The position of the second opening 15+ on the substrate side is the same as that of the first opening 1.
Even if the brocade of No. 41 is 0.5 μm, it becomes about 0.15 μm.

A film J11 is formed on this first photoresist 121.
．． 5pm of a second photoresist (e.g. containing a photosensitizer)
The entire recessed portion 16 is formed by fusuma etching.

Subsequently, a gate metal such as At (gold j
! 11111) (7) Fully evaporated (Figure c in Figure 1), gate electrode (8) is completely formed by lift-off method (Figure C6 in Figure 1)
) ) 0(g(＠Effect of Akira) As is clear from the above explanation, the width of the second opening on the substrate side is narrower than that of the first opening. It is possible to obtain a gate electrode with a gate length seven times longer than the #1 width that can be achieved with photoetching, and
Significant improvement in HEMT characteristics? can be achieved.

[Brief explanation of the drawing]

Fig. 1 [al to +81] is a diagram showing the prescribed process costs for explaining the method of the present invention; II...Substrate%121...First photoresist,
+31...second photoresist, +41...first
f[L, +51...second opening, Ifi l...
Recess evil, f7+... gold R model.

Claims (1)

[Claims] 1. Forming a first photoresist on the substrate;
forming a second photoresist on the first photoresist; forming a first hole in the second photoresist; forming a tapered second opening that widens as it moves away from the substrate; forming a metal film on the substrate from the second opening;
A method for manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, wherein the etching is ion beam etching.