Effects of O 2 Feed Gas Impurity on Cl2 Based Plasma Etching of Polysilicon
| Autor: | Gavin C. H. Zau, Herbert H. Sawin |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Plasma etching
Silicon Renewable Energy Sustainability and the Environment fungi technology industry and agriculture Oxide Analytical chemistry chemistry.chemical_element macromolecular substances Plasma Photoresist Condensed Matter Physics Surfaces Coatings and Films Electronic Optical and Magnetic Materials chemistry.chemical_compound stomatognathic system chemistry Impurity Etching Materials Chemistry Electrochemistry Reactive-ion etching |
| Zdroj: | Journal of The Electrochemical Society. 139:250-256 |
| ISSN: | 1945-7111 0013-4651 |
| Popis: | The effect of low level, between 0.001 and 10%, addition on based plasma etching of polysilicon in a parallel‐plate etcher was investigated. Three strong effects on the etching rate of unmasked polysilicon were observed. Low level addition, 0.1–2%, enhanced the etching rate up to 4 times that of the pristine system. High level addition, ≥6%, stopped the etching altogether. Pure plasma etching rates were enhanced by previous runs with addition; a hysteresis effect. The hysteresis was reduced by subsequent system plasma exposure. Running a plasma after addition runs cleaned the system and returned it to its pristine state. The stopping of etching at high levels was attributed to plasma oxidation of the polysilicon surface; since plasmas are very selective with respect to oxide, the etching is stopped by the surface oxide. Both the low level etching rate enhancement and the hysteresis effect can be attributed to the deposition of an oxychloride film on the etcher surfaces. The oxychloride film, formed by reaction between the etching products and the added , passivates the interior etcher surfaces against Cl surface recombination, and, therefore, reduces the major Cl loss mechanism. The gas‐phase Cl concentration increases, which in turn increases the polysilicon etching rate. These results demonstrate the importance of etcher surface condition and of the etching product deposition. Photoresist masked polysilicon films etched in the same configuration showed similar addition dependencies as unmasked polysilicon films. The main difference is that the addition effect thresholds are higher with the photoresist mask due to the consumption of the added by photoresist etching. Unmasked polysilicon film etched in a commercial etcher, Applied Materials Precision 5000, under magnetically enhanced reactive ion etching configuration, exhibited the same trends as in the parallel‐plate research etcher. This indicates that results obtained from the parallel‐plate research etcher can be generalized to other configurations. |
| Databáze: | OpenAIRE |
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