JPH0334319A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To ravel out a side etching and residue, and to reduce the amount of thinning of the lower insulating film by a method wherein a second high melting point metal film, consisting of the same material as that of a first film, is deposited thicker than the first high melting point metal film, and the flat part of the second high melting point metal film is etched by conducting a reactive ion etching treatment again. CONSTITUTION:An insulating film 2, a first titanium-tungsten film 3 which is a high melting point metal and used as a barrier metal, and an aluminum film 4 are deposited successively on the surface of a silicon substrate 1, and a wiring pattern is formed on a photoresist film 5. Then, an aluminum wiring 4A is formed by etching the aluminum film 4 by conducting a reactive ion etching method using chlorine gas. Then, after the photoresist film 5 has been removed, a second titanium-tungsten film 6 is deposited again. An etching treatment is conducted until the second titanium-tungsten film 6 is removed from its flat part by conducting a reactive ion etching method. At this time, a second titanium-tungsten film 6A is left on the side wall of the aluminum wiring 4A. Then, the first film 3 and the film 6A are etched by conducting an isotropic etching treatment.

Description

Detailed Description of the Invention] Industrial Application Field 1 The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a wiring having a barrier metal.

1. Prior Art j A two-step etching method using dry etching is widely used as a method for forming aluminum interconnections containing barrier metal.

First, as shown in FIG. 2 (a), an insulating film 2, titanium tungsten M3, which is a barrier metal, and an aluminum film Q4 are sequentially deposited on the surface of a silicon substrate 1, and then wiring is formed on a photoresist film 5. form a pattern.

Next, as shown in FIG. 2(b), the aluminum film 4 is etched by reactive ion etching using chlorine-based gas to form an aluminum wiring 4A.

Next, as shown in FIG. 2(c), the titanium-tungsten film 3 is etched by reactive ion etching using fluorine thread or 4i chlorine-based gas to complete the formation of the aluminum wiring 4A.

(Problems to be Solved by the Invention) In the conventional manufacturing method described in the previous section, side etching 7 of the high melting point metal film 3 may occur as shown in FIG. 2(C).

Further, in the case of zero reactive ion etching, the residue 8 that causes an increase in leakage current is likely to remain, and in order to remove the residue 8, over-etching is necessary, which increases the amount of film reduction of the underlying insulating film 2.

An object of the present invention is to eliminate side etching and residue of a high melting point metal film and to reduce the amount of film loss of the underlying insulation layer.

(Means for Solving the Problems) The method for manufacturing a semiconductor device of the present invention includes sequentially depositing an insulating film and a first high melting point metal on the surface of a semiconductor substrate, and then depositing an aluminum 1 model or an aluminum alloy film. Using the photoresist film of the wiring pattern as a mask, the aluminum film or aluminum alloy film is subjected to reactive ion etching, and then the film is removed to the photoresist 1. depositing a second high melting point metal film thicker than the first high melting point metal film;
By etching the flat part of the high melting point metal film (G) again by reactive ion etching, the first film is etched.
The layer is formed by isotropically etching the high melting point metal film and the second high melting point metal film remaining on the side wall of the wiring of the aluminum 1 pattern or aluminum alloy film that has already been patterned.

[Example" Next, the present invention will be explained with reference to the drawings.

First, as shown in FIG. 1(a), an insulating film 2 is formed on the surface of a silicon substrate 1, a first titanium tungsten film 3 (thickness: 0.1 μm), which is a high melting point metal, and an aluminum film 4 (thickness: A wiring pattern is formed on the photoresist film 5 by sequentially depositing 0.8μ+n.

Next, as shown in FIG. 1(b), the aluminum film 4 is etched by reactive ion etching using a chlorine-based gas (for example, BCe or CC!!4) to form an aluminum wiring 4A.

As shown in 1st I21(c),
After removing the resist film 5, a second titanium-tungsten film 6 (thickness: 0.2 μxn) is deposited again. The second titanium tungsten film 6 must be thicker than the first titanium tungsten film 3.

Next, as shown in FIG. 1(d), the second titanium-tungsten film on the flat portion is etched by reactive ion etching using a fluorine thread gas (for example, CF or 5F6) until the second titanium-tungsten film is also completely removed. In the second case, the second titanium-tungsten film 6A remains on the side wall of the aluminum wiring 4A.

Since the first titanium-tungsten film 3!3A must remain at this time, it can be seen that the second titanium-tungsten film 6 must be thicker than the first titanium-tungsten film 1!3A.

-) Next, as shown in FIG. 1(e), the first titanium-tungsten film 3 and the aluminum wiring 4 are etched by isotropic etching (for example, wet etching using H2O2 or plasma etching using CF4+02 gas).
The second titanium tungsten film 6A on the side wall of A is etched.

As the high melting point metal films 3 and 6, it is also possible to replace the titanium tungsten film with a titanium film or a titanium nitride film.

It is also possible to replace the aluminum film used in the first embodiment with an aluminum-plated gold film.

(Effects of the Invention) As explained above, the present invention removes the second titanium tungsten film 6A on the side wall of the aluminum wiring 4A by isotropic etching, thereby eliminating the side etching 7 and the residue 8, and removing the underlying layer. This has the effect of reducing the amount of film loss in the insulating film 2.

[Brief explanation of drawings]

FIGS. 1(a) to <e) are sectional views showing an embodiment of the present invention in the order of steps, and FIGS. 2(a) to 2(C) are sectional views showing the conventional technique in the order of steps. ■...Silicon substrate, 2...Insulating film, 3...Titanium tungsten film, 3A...First titanium tungsten film, 4...Aluminum 1 model, 4A...Aluminum wiring, 5...・F1~Resist film, b...Second titanium tungsten film, 6A...Second titanium tungsten film on side wall, 7...Side etching, 8...
Residue. Acting Patent Attorney Uchihara Mukashidai! figure

Claims (1)

[Claims] After sequentially depositing an insulating film and a first high-melting point metal on the surface of a semiconductor substrate, an aluminum film or an aluminum alloy film is deposited, and then the aluminum film or aluminum alloy film is deposited using a photoresist film of a wiring pattern as a mask. After reactive ion etching, the photoresist film is removed, and a second high melting point metal film made of the same material as the first high melting point metal film is deposited to be thicker than the first high melting point metal film, and then the photoresist film is removed again. By etching the flat part of the second high melting point metal film by reactive ion etching, the remaining portions of the wiring of the first high melting point metal film and the already patterned aluminum film or aluminum alloy film are removed. A method for manufacturing a semiconductor device, comprising isotropically etching a second high melting point metal film.