1) Field of the Invention
This invention relates generally to fabrication of semiconductor devices and more particularly to the fabrication of an oxynitride layer for use as an anti-reflective coating (ARC) or as a stop layer having low leakage current.
2) Description of the Prior Art
The semiconductor industry's continuing drive toward integrated circuits with ever decreasing geometries, coupled with its pervasive use of highly reflective materials, such as polysilicon, aluminum and metal silicides, has led to increased photolithographic patterning problems. Unwanted reflections from these underlying materials during the photoresist patterning process cause the resulting photoresist pattern to be distorted. The use of an anti-reflective coating (ARC) has become popular in the semiconductor industry to prevent distortion of photoresist patterns. An Anti-Reflection Coating (ARC) is a layer of electiomagnetic energy absorbing material formed subjacent to a photoresist layer to minimize pattern distortion caused by reflection. Oxynitride can be used to form anti-reflective coatings.
Importantly, the inventors have found that to increase manufacturing efficiency, it would be advantageous in the semiconductor industry to use an ARC as a dielectric in subsequently defined semiconductor devices. However, the inventor's have found that oxynitride ARCs exhibit leakage currents that prevent their use as a dielectric in a semiconductor device.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering the following patents.
U.S. Pat. No. 5,639,687 (Roman et al.) discloses a process of making a Si-rich silicon oxynitride layer.
U.S. Pat. No. 5,365,104 (Godinho et al.) shows a SiON process for making a silicon oxynitride passivation layer.
U.S. Pat. No. 4,717,631 (Kaganowicz et al.) shows a method for making SiON having a specific low Hydrogen % range.