Optimization Of A Highly Selective Nitride/Oxide Rie In A Batch Etching Machine By Statistical Analysis

F. N. Hause; H. J. Stocker; R. O. Lynch

doi:10.1117/12.978061

30 January 1990 Optimization Of A Highly Selective Nitride/Oxide Rie In A Batch Etching Machine By Statistical Analysis

F. N. Hause, H. J. Stocker, R. O. Lynch

Proceedings Volume 1185, Dry Processing for Submicrometer Lithography; (1990) https://doi.org/10.1117/12.978061
Event: 1989 Microelectronic Integrated Processing Conferences, 1989, Santa Clara, United States

Abstract

We describe the characterization and optimization of a two step nitride etch process in a hexode reactor by Design of Experiments and Statistical Process Control methods. Through optimization, better process control is achieved thus allowing a more robust process. Response Surface Analysis of a full factorial screening experiment with four factors points towards using a two step process of using first a CHF3-rich CHF3/O2 gas mixture with high nitride to photoresist selectivity but low nitride to oxide selectivity followed by a second step with high nitride to oxide selectivity but low nitride to photoresist selectivity. Further optimization of the nitride etch rate and uniformity through the path of steepest ascent method is investigated. The process recipe thus developed was used for etching gate and source patterns in a 0.9 micron CMOS TWIN TUB technology for 125 and 150 mm wafers in a commercial hexode. Penetration of the thin pad oxide is about 30+ /- 10A. The highest nitride to oxide selectivity for the second step is about 12 to 1 at an approximate 10% CHF3/90% 02 gas mixture. Statistical process control is demonstrated.

Citation Download Citation

F. N. Hause, H. J. Stocker, and R. O. Lynch "Optimization Of A Highly Selective Nitride/Oxide Rie In A Batch Etching Machine By Statistical Analysis", Proc. SPIE 1185, Dry Processing for Submicrometer Lithography, (30 January 1990); https://doi.org/10.1117/12.978061

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