JPH0350828A - Method of forming gold wiring - Google Patents

Abstract

PURPOSE:To prevent resist from readhering to gold and to prevent the short between wirings by selectively etching a metallic film by reactive ion etching, and etching the gold by ion milling with the metallic film as a mask. CONSTITUTION:Gold 2 is formed on an insulating film 2, and next, for example, tungsten 4 is formed, and by the photoresist 1 to form a metallic film, a wiring pattern is formed. Next, by reactive ion etching, the tungsten is etched, and the photoresist 1a is removed and a tungsten mask 4a is formed. After that, by an ion milling device, gold is etched by ion milling with metallic film as a mask.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming fine interconnections using gold.

Background Art] With the recent increase in the degree of integration of semiconductor devices, the reliability of wiring structures formed on substrates has become increasingly important. Therefore, for applications that require high reliability,
Gold is used as the wiring material. The fine gold wiring is the third
It is formed by the method shown in Figures (a) to (c). The steps will be explained below in order.

As shown in FIG. 3(a), a photoresist 1 is applied to a thickness of about 1 μm on the gold 2 formed on the insulating film 3 to form a wiring pattern. Next, as shown in FIG. 2B, gold 2 is sputter-etched using argon using the photoresist 1 as a mask using an ion milling apparatus. Finally, the same figure (C)
The photoresist 1a was peeled off to form gold wiring as shown in FIG.

[Problem to be solved by the invention]

In the conventional manufacturing method described above, during sputter etching using an ion milling device, gold re-adheres to the side surface of the photoresist pattern 1a as shown in 2b in FIG. The gold that was reattached to the
As shown in FIG. 4(c), there is a problem in that adjacent wirings are short-circuited, significantly reducing the reliability of the semiconductor device.

[Means to solve the problem]

The method for forming gold wiring according to the present invention includes a step of forming gold on an insulating film, a step of forming a metal film, a step of forming a wiring pattern using a resist pattern, and a step of etching the metal film by reactive ion etching. and a step of etching the gold by ion milling using the metal film as a mask after removing the resist.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(d) are cross-sectional views shown in the order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 1(a), gold 2 is deposited on the insulating film 3 at 0.000.
After that, tungsten (4) is formed to have a thickness of 0.15μ, and a wiring pattern is formed using photoresist (1). Next, as shown in the same figure (b), the tungsten was etched for 8 minutes by reactive ion milling using CF gas.
As shown in FIG. 2C, the photoresist 1a is removed to form a tungsten mask 4a. After that, the same figure (d)
As shown in Figure 2, gold is etched using an ion milling device under etching conditions of beam energy of 500 eV and beam current of 1 mA/cf. In this case, since the etching speed is 1400 etching/min for gold and 340 etching/min for tungsten, the optimum etching time is 4 minutes.

When a photoresist with a thickness of about 1 μm is used as a mask for the gold wiring formed in this manner, the problem of peeling off of redeposited gold after the resist is removed does not occur. That is, since a thin tungsten film with a thickness of 0.15 μm is used as the mask material, the amount of gold redeposited onto the mask material is extremely small. Furthermore, since the tungsten used as the mask material is a metal, it can be used as is as a wiring and does not need to be removed unlike photoresist. Therefore, since there is no need for a stripping process, redeposited gold will not be peeled off.

FIGS. 2(a) to 2(e) are longitudinal sections of other embodiments of the present invention. In this example, titanium 15 is grown on the insulating film 3, and gold is further grown thereon.

Titanium 14 is also used as a gold etching mask. The etching rate of titanium in ion milling is about the same as that of tungsten.

In this example, the titanium 14 of the mask material shown in FIG.
The etching is carried out by reactive ion etching using C (14 gas).
The process of etching titanium using a mask can also be easily performed by reactive ion etching using C (14 gas).

Other examples of metal films that can be used as mask materials that can be easily subjected to reactive ion etching include molybdenum, aluminum, chromium, and tantalum, and the present invention can also be implemented using these materials.

〔Effect of the invention〕

As explained above, the present invention can prevent gold from re-adhering to the resist by replacing the mask material from the resist with a metal film that can be subjected to reactive ion etching during ion milling of gold wiring. Short circuits between wires can be prevented, and the reliability of gold wires can be improved.

[Brief explanation of drawings]

1(a) to (d) are process cross-sectional views showing one embodiment of the present invention, FIGS. 2(a) to (e) are process cross-sectional views of another embodiment of the present invention, and FIG. a) to (c) are process cross-sectional views showing a conventional method. 1.1a...Photoresist, 2.2a, 2b
...Gold, 3...Insulating film, 4.4a, 4
b...Tungsten, l 4. 14a,
14 b-titanium, 15° 15a... titanium.

Claims (1)

[Claims] A method for forming a gold wiring includes a step of forming gold on an insulating film, a step of forming a metal film, a step of selectively etching the metal film by reactive ion etching, and a step of using the metal film as a mask. A method for forming a gold wiring, comprising a step of etching the gold by ion milling.