IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Wednesday Sessions
       Session TF-WeM

Paper TF-WeM9
Gas and Surface Reactions of Radicals in Hot Wire CVD of Amorphous Silicon

Wednesday, October 31, 2001, 11:00 am, Room 123

Session: Fundamentals of Deposition
Presenter: H.L. Duan, Stanford University
Authors: H.L. Duan, Stanford University
G.A. Zaharias, Stanford University
S.F. Bent, Stanford University
Correspondent: Click to Email
Hot wire chemical vapor deposition (HW-CVD) is a relatively new growth method that has been shown to produce amorphous and microcrystalline silicon materials of superior quality in comparison to the more conventional plasma enhanced chemical vapor deposit ion (PECVD). By using this technique, the precursor molecule such as silane is dissociated on a metal filament (wire) heated to high temperature. Radical species produced from the filament subsequently either diffuse to the substrate to form the film or react to form secondary products. In this study, a laser-based soft ionization method utilizing the ninth harmonic of a Nd:YAG laser has been applied for the first time to probe various silicon-containing species simultaneously during the growth process. In addition to the detection of gas phase radicals, multiple internal reflection infrared spectroscopy is used to characterize the hydride bonding and film structure. Surface and gas phase species are followed as a function of important growth parameters such as filament temperature, filament material and substrate temperature. It is shown that Si, SiH@sub 3@, and Si@sub 2@H@sub 6@ are the major silicon-containing species evolved upon activating silane with the hot wire. However, even at low gas pressure the filament condition and chamber history are found to influence the radical species produced. Further study of the gas species generated by W and Re filaments at wire temperatures between 1000@super o@C and 2000@super o@ C indicates that heating the fil ament to higher temperatures increases the flux of Si, SiH@sub 3@, and Si@sub 2@H@sub 6@ differently. Above 1800@super o@C, the Si intensity saturates, while SiH@sub 3@ and Si@sub 2@H@sub 6@ show a monotonic increase without saturation up to 2000@super o@C. A growth mechanism consistent with these observations will be discussed.