Properties of Chemical Vapor Deposited Tungsten Silicide Films Using Reaction of  WF 6 and Si2 H 6

Abstract

Tungsten silicide films were formed by the chemical vapor deposition method using the reaction WF6 and Si2H6 . The deposition rate, resistivity, composition, stress, crystal structure, and content of impurities were studied and compared with tungsten silicide films deposited by reaction of WF6 and SiH4 . The tungsten silicide films made using Si2H6 have a higher deposition rate and higher Si concentration than those made by using SiH4 at the same substrate temperature. For these reasons, the tungsten silicide films made by using Si2H6 were found to have a resistivity that is a little higher and, after annealing, a stress that is smaller than that made by SiH4 . Also, the resistance of tungsten silicide to peeling is larger than that of the film made by using SiH4 . The crystal structure of the WSix films made by Si2H6 is almost the same as that made by SiH4 ; however, a tetragonal W5Si3 structure easily forms even in Si‐rich films of WSi2.6 . Content of fluorine in films made by Si2H6 is smaller than that in films made by SiH4 .

Low Temperature Chemical Vapor Deposition of Silicon-rich Tungsten Silicide Films from Tungsten Hexafluoride - Disilane Pre-activated Mixtures

“…Figure 7 shows x of WSi x determined with RBS vs. T s . The Si content in Si-rich WSi x films increased with increasing T s when conventional heating was used, similar to the results reported by Shioya et al (Shioya et al 1987b). For 80 < T s < 150°C the Si content of their films was independent of T s , and increased for T s > 180°C.…”

“…The WF 6 /SiH 4 gas system can be used to produce WSi x films at relatively low temperatures compared with the WF 6 /SiH 2 Cl 2 system. High concentrations of residual fluorine atoms and poor step coverage of films are major drawbacks of this gas system (Shioya et al 1985, Togei 1986, Shioya et al 1986a, Shioya et al 1987a, Shioya et al 1986b, Hara et al 1984, Shioya et al 1987b, Shioya et al 1987c, Hara et al 1987, Joshi et al 1988, Fujimura et al 1989,Kobayashi et al 1989, Shenai et al 1991. In the CVD from WF 6 and SiH 2 Cl 2 , erosion by halogens is severe and the uniformity of film thickness and resistivity are poorer than those in the CVD from WF 6 and SiH 4 (Wu et al 1988, Hara et al 1989, Hara et al 1990, Raupp et al 1990, Washidzu et al 1991, Telford et al 1993a, Telford et al 1993b.…”

Annealing Behaviour of WSix Films Prepared By CVD

“…Often these parameters are ignored when designing an annealing process for films with different structures and compositions, as a result we find most reports using a standard annealing process without considering the differences in the films. Shioya et al have studied the effect of first three parameters on the annealing behaviour of silicide films deposited by CVD technique [5,6]. In this paper we demonstrate how reactivity of substrate changes the phase transformation kinetics of WSi x films.…”

Atomic Layer Deposition of Cobalt Silicide Thin Films Studied by in Situ Infrared Spectroscopy

“…For direct silicide deposition, different techniques are used, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). Although PVD is most commonly used, it suffers from limited step coverage, leading to poor conformality, especially in deep contact holes. ,, CVD has also been used for some materials (e.g., WSi 2 ), , but the conformality of CoSi 2 films is necessary to minimize the consumption of Si and avoid the degradation of pn junctions and still cannot be achieved with CVD. Consequently, atomic layer deposition (ALD), through its sequential and self-limiting surface reactions, is most attractive to deposit silicides due to its simplicity, reproducibility, and the high conformality of the resulting films .…”