Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
1997-12-08
2001-12-11
Dang, Thi (Department: 1763)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S725000
Reexamination Certificate
active
06329298
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of treating samples, and particularly to a method of treating samples adapted to corrosion prevention treatment of aluminum-containing wiring materials after they have been subjected to the etching treatment.
2. Description of the Prior Art
According to a conventional method of treating aluminum-containing wiring materials as disclosed in, for example, Japanese Patent Publication No. 41766/1983, a semiconductor wafer on which an aluminum-copper alloy film is formed is set in a reactive sputter-etching apparatus, the aluminum-copper alloy film is patterned using a plasma of such a gas as BCl
3
, CCl
4
, PCl
3
, BBr
3
or the like, a hydrogen plasma is generated in the same apparatus, and the patterned aluminum-copper alloy film is exposed to the hydrogen plasma so as to be anti-corrosion treated.
In the above conventional technology, however, no attention has been given to removing residual or adhered matter after the etching treatment. In carrying out the etching treatment, in general, the aluminum-containing wiring material (hereinafter referred to as “wiring film”) is masked with a photoresist or the like. The wiring film, in this case, may be aluminum-containing films (Al, Al—Si, Al—Cu, Al—Si—Cu, etc.) and laminated wiring films such as aluminum-containing film + barrier metal, cap metal, reflection-preventing film + aluminum-containing film + barrier metal. (The barrier metal is composed of TiW, TiN or the like, and is provided between the silicon substrate and the aluminum-containing film, in order to prevent defective junction due to mutual diffusion of the silicon substrate and the aluminum-containing film and to prevent the wiring resistance from increasing due to the precipitation of silicon in the aluminum-containing film. The cap metal is composed of TiW, TiN, MoSi, or the like, and is used as the uppermost layer of the wiring film of a laminated structure, or is used as the reflection-preventing film. The reflection-preventing film is formed on the aluminum film to suppress the reflection of light at the time of exposure, so that there is formed a resist pattern faithful to the mask.) The etching treatment is effected to treat the wafer on which the wiring film is formed using the plasma of a single gas of the type of halogen such as BCl
3
, Cl
4
, SiCl
4
, HBr, BBr
3
or the like, or a mixture gas thereof. The etching treatment is usually the one that is called reactive ion etching. With the reactive ion etching, the wiring film is etched maintaining a pattern faithful to the mask due to the interaction of radicals and ions in the plasma of the halogen-type gas, and the wiring pattern is obtained.
On the thus etched wiring pattern remains a photoresist (hereinafter referred to as “resist”) which is a masking material. Halogen components in the plasma adhere on the surface of the resist during the etching and halogen components are implanted due to the bombardment of ions. On the side wall of the etched wiring pattern are adhered the halogen components during the etching or the resist components sputtered by the bombardment of ions. Moreover, aluminum component of the once etched wiring film adhere on the side walls again thereby to form a layer that is called side wall. This layer consists of such components as aluminum, chlorine, carbon, hydrogen, etc. that are adhered in a random fashion.
According to the above-mentioned conventional technology, a hydrogen plasma is generated in the apparatus after the etching treatment, and the patterned aluminum-copper film is exposed to the hydrogen plasma so that the aluminum-copper alloy film is anticorrosion-treated. In the treatment with hydrogen plasma, the halogen components adhered to the surfaces between the resist and the wiring pattern or adhered to the portions very close to these surfaces, undergo the reaction with hydrogen in the hydrogen plasma and can be removed as hydrogen chloride (HCl) or hydrogen bromide (HBr). However, the halogen components remaining in the resist and in the side walls are not allowed to come in contact with the hydrogen plasma and cannot be removed. Therefore, corrosion easily takes place in the wiring film due to the local battery action between the wiring film materials (between different metals) of the laminated structure or due to halogen components in the side wall (hereinafter referred to as “residual adhered matter”).
Japanese Patent Laid-Open No. 43132/1987 can be cited as a prior art related to the present invention. This prior art discloses a method of plasma treatment to remove organic film (resist) on the silicon substrate in the plasma of an oxygen gas obtained by adding a compound containing at least carbon or oxygen to the oxygen, e.g., by adding methanol (CH
3
OH) to the oxygen. According to this prior art, the rate of removing resist is increased (relative to the treatment using the oxygen gas plasma) and damage is prevented owing to the treatment with the plasma of a gas obtained by adding methanol (CH
3
OH) to the oxygen (O
2
). However, this prior art is quite silent about the prevention of corrosion of the wiring film (aluminum-containing wiring material).
According to another prior art disclosed in Japanese Patent Publication No. 30268/1987, the aluminum film or the aluminum alloy film is etched using a halogen compound gas, and is then subjected to the anticorrosion treatment using the plasma of a mixture gas consisting of fluorocarbon (CF
4
) and oxygen (O
2
) without taking the aluminum film or the aluminum alloy film out of the container.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method of treating samples which is capable of imparting high corrosion preventing performance to the aluminum-containing wiring materials.
The present invention is concerned with a method of treating samples comprising a step for etching a sample of aluminum-containing wiring material using a halogen-type gas; a step for removing resist using a gas that contains oxygen component; and a step of anticorrosion treatment using a gas that contains hydrogen component. After the etching treatment, the aluminum-containing wiring material is treated with the plasma of a gas that has oxygen component, such that the resist provided on the aluminum-containing wiring material is reacted with oxygen and is removed. The aluminum-containing wiring material is further treated with the plasma of a gas that contains hydrogen component or is treated by liquefying such a gas into droplets thereof on the surface of the sample. Therefore, the halogen components (Cl, Br, etc.) adhered to the aluminum-containing wiring material during the etching treatment undergo the reaction with hydrogen and are effectively removed in the form of hydrogen chloride (HCl) or hydrogen bromide (BBr). Thus, high corrosion prevention performance is imparted to the aluminum-containing wiring material.
REFERENCES:
patent: 4138306 (1979-02-01), Niwa
patent: 4325984 (1982-04-01), Galfo et al.
patent: 4927484 (1990-05-01), Mitomi
patent: 4961820 (1990-10-01), Shinagawa et al.
patent: 4983254 (1991-01-01), Fujimura
patent: 5221424 (1993-06-01), Rhodes
patent: 5545289 (1996-08-01), Chen
patent: 078224 (1983-05-01), None
patent: 140201 (1985-05-01), None
patent: 247603 (1987-12-01), None
patent: 5591842 (1980-07-01), None
patent: 6430225 (1989-02-01), None
patent: 6448421 (1989-02-01), None
Extended Abstracts vol.. 80-2, Oct. 1980 pp. 851-853 Abstract No. 329, Application of plasma etching to multilevel metal structures.
IBM Technical Disclosure Bullentin, vol. 24, No. 113, Apl. 1982-Plasma Corrosion Inhibition (Potts).
Tsukada et al After Corrosion Treatment in Aluminum Alloy Reactive Ion Etching, ElectroChem. Soc. 1983 pp. 341-352.
Fukuyama Ryooji
Kakehi Yutaka
Kawahara Hironobu
Kawaraya Akira
Nawata Makoto
Antonelli Terry Stout & Kraus LLP
Dang Thi
Hitachi , Ltd.
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