Analysis of a TEOS/Oxygen Plasma: Influence of Energy and Particle Flux on the Deposition Parameters
- PDF / 1,264,347 Bytes
- 6 Pages / 412.2 x 633.6 pts Page_size
- 84 Downloads / 237 Views
ABSTRACT In this work we looked at deposition parameters such as rate and film microstructure during the plasma enhanced CVD processing of TEOS {Si (OCH 2 CH 3 )4) + 02. This is a multicomponent oxide due to the inevitable accidental inclusion of carbonatious contaminants. We decided to characterize the plasma parameters, namely the electron energy (from 50 to 600 eV), and the flux of the reactive species. The deposition chamber was modified by the introduction of a stainless steel tubular ring between the electrodes, such that when a positive bias is applied it is possible to inject electrons into the plasma. A dual role for the tubular ring is the transport of oxygen to different locations in the plasma, and to monitor the influence of the oxygen flux on deposition. The experimental results showed that by increasing the voltage bias on the ring from 0 to 600 V, the oxide deposition rate is enhanced. For low precursor concentration (TEOS), the deposited films shows micro-structural improvement as evidenced by FTIR spectroscopy. We monitored the formation of carbon compounds by their RAMAN signature, and one can see that for small ring bias, the concentration of carbon contaminants is large and it decreases with increasing electron energy. A reaction model consistent with our experimental results must consider the need of oxygen ions in the oxidation of the precursor. Since an increase in the electron flux hinders the formation of oxygen ions, a pressure decrease must be utilized to improve the chemical properties of the film such as the formation of carbonatious contaminants. The inescapable conclusion is that higher density plasmas favor the processing of organosilicates. INTRODUCTION Oxide films deposition utilizing an oxygen plasma and e organosilicate such as TEOS, is a common practice in micro-electronics and micro-fabrication [1-3]. This oxide precursor is particularly utilized for its good step coverage [4-5] an essential characteristic for interconnections and multi-level technology. Even though TEOS technological importance may be high, its reaction mechanisms during plasma deposition are not yet well understood. Previous studies show that carbon compounds incorporation in the film are possible and that these compounds degrade the film electrical characteristics as well as preventing the complete oxidation of the precursor molecule [6-9]. These studies do not usually consider the electron energy effects on the chemical reactions, particularly its effect on the multiple ion / molecule interactions that occur during deposition[ 10-12]. This article reports our findings characterizing the main features of the films when two of the most important plasma parameters are systematically modified, namely the electrons energy and the gas flowing into the plasma chamber, in particular oxygen.
63 Mat. Res. Soc. Symp. Proc. Vol. 606 ©2000 Materials Research Society
EXPERIMENTAL Set-up and Instrumentation The experimental set-up has been previously described elsewhere [7]. It is fundamentally a home built multi-cham
Data Loading...
