SSL Seminar Series 2001 No. 3
Title: Reaction Mechanism of Si3N4 Plasma Enhanced Chemical Vapour Deposition and Its Mechanism
Speaker: Mr. Yang Shuowang
Date:
2nd February 2001, Friday
Time: 5:00-6:00pm
Venue: Physics Resource Room S13, 02-16

Abstract
Approximately 40% of the steps in the fabrication of microelectronics use plasma processes. One process which has been investigated extensively and applied widely over the last decade is plasma enhanced Chemical Vapour Deposition (PECVD).

Silicon nitride, Si3N4, thin film deposited by plasma-enhanced CVD has been studied for over two decades and is widely used in the semiconductor industry as a passivating coating, a diffusion barrier, and more recently as a gate dielectric and inter-level metal isolation in amorphous Si thin film circuitry. Silicon nitride can also be deposited by thermal CVD, but plasma enhanced CVD allows process carried out at much low temperature which are compatible with more of the steps in semiconductor manufacturing processes. However, PECVD film is not general stoichiometric Si3N4 and is more properly described as SixNyHz. In real case of manufacturing process, PECVD is extraordinarily complex and deposition characteristics depend strongly on gas pressure, flow rate, RF power and frequency, reactor geometry and substrate temperature. The process is high technical containing and high cost consuming. Therefore, computer modelling of PECVD is always a will of both for industrial engineers and researchers. So fundamental understanding of plasma processes is required in simulation work.

Currently there are two approaches of method in PECVD modelling, Monte Carlo statistical and molecular dynamic approach. In current work, molecular dynamic approach is the major tool assisted with ab initio or semi-empirical quantum chemistry. The plasma and a surface CVD chemistry mechanism of Si3N4 are proposed by several hundreds of chemical reactions described with respective thermodynamic and kinetic parameters. Some popular software such as ChemKin, Gaussian 98 and F*A*C*T were used in this work. The simulation results well agree with the experimental data.

PROFILE OF PRESENTER
Mr. Yang Shuowang obtained his first degree in physical chemistry in 1985 from Zhejiang University and three years later he obtained his Master degree in the field of inorganic chemistry from the same university. His second master degree is in organic and nature products chemistry from National University of Singapore in 1996. Currently he is a senior research engineer in Institute of High Performance Computing.