Semiconductor device manufacturing: process – Making device or circuit responsive to nonelectrical signal – Responsive to electromagnetic radiation
Reexamination Certificate
2001-07-18
2003-03-04
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Making device or circuit responsive to nonelectrical signal
Responsive to electromagnetic radiation
C438S954000
Reexamination Certificate
active
06528341
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a method of forming an antireflection film of silicon oxynitride (SiON) on a surface of a semiconductor substrate and more particularly to an SiON antireflection film which is noncontaminating with respect to photoresists and more specifically deep-ultraviolet or chemical-amplification photoresists used during the process of fabricating semiconductor devices such as integrated circuits.
2. Description of the Related Art
The continual trend in the semiconductor industry toward fabricating integrated circuits with ever-decreasing geometry has led to an increase in problems associated with the formation of the photoresist masks for photolithographically etching the circuits.
Spurious reflections due to the underlying materials cause distortion of the resulting photoresist patterns.
This problem is exacerbated in the case of technologies smaller than 0.25 &mgr;m in which deep-UV radiation (wavelengths of 248 nm or less) and deep-UV or chemical-amplification photoresists (DUV photoresists) are used for the photolithographic etching.
To remedy this problem of spurious reflections, an antireflection film is disposed between the surface of the substrate to be photolithographically etched and the layer of photoresist.
Various materials, such as Si
3
N
4
and silicon oxynitride, have been proposed for making the antireflection films.
Unfortunately, when carrying out deep-UV photolithography using a deep-UV or chemical-amplification photoresist on an antireflection film, for example made of silicon oxynitride, a “stub” appears the interface between the photoresist and the silicon oxynitride film due to interaction between the photoresist and the nitrogen contained in the film. The appearance of this “stub” impairs the subsequent etching step and control of the dimensions of the etched feature.
To help overcome this drawback, it has been proposed to form a thin silicon oxide layer on the silicon oxynitride antireflection film using an oxygen plasma.
The silicon oxide layer must be as thin a possible so that the optical properties of the antireflection film are not degraded and the film can be easily removed during subsequent photolithographic etching steps.
Moreover, creating the oxygen plasma in situ (i.e. in the same reactor chamber as that in which the SiON antireflection film was deposited) results in the formation of particles on the substrates subsequently introduced into the reactor chamber. This contamination of the substrates impairs the quality of the semiconductor devices produced.
The present invention therefore provides a method of forming a silicon oxynitride antireflection film on a semiconductor substrate, which film is noncontaminating with respect to photoresists, in particular for deep-UV photolithographic etching, and avoids the contamination of silicon oxynitride antireflection coatings deposited on substrates successively introduced into the same reactor.
REFERENCES:
patent: 5710067 (1998-01-01), Foote et al.
patent: 6004850 (1999-12-01), Lucas et al.
patent: 6013582 (2000-01-01), Ionov et al.
patent: 6326231 (2001-12-01), Subramanian et al.
Gaillard Frederic
Schiavone Patrick
France Telecom
Meyertons Eric B.
Meyertons Hood Kivlin Kowert & Goetzel P.C.
Nelms David
Nhu David
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