Model Studies of LCVD of Transition Metals on Silicon: Surface Processes
Investigation of laser- and thermally-induced reactions of refractory metal complexes adsorbed on silicon surfaces is of both technological and fundamental importance. The technical goal of laser-assisted chemical vapor deposition of refractory metal films is to rapidly deposit high conductivity films that adhere well to the semiconductor substrate.1,2 In most work to date refractory metal carbonyls were used as precursors for the deposition process3–10 due to their high volatility and rich gas phase photochemistry. Unfortunately, high quality films have not been fabricated by laser-assisted deposition of refractory metals using the respective metal carbonyls; low conductivity films are formed due to the presence of carbon and/or oxygen impurities and highly porous film morphology. The impurities in the film may be incorporated during the laser deposition process from dissociation of the CO or other ligands trapped on the surface or from secondary surface reactions of molecules present in the ambient background under practical LCVD conditions.11 It is our challenge to determine the origin of the carbon and oxygen contamination and possibly suggest methods for minimizing impurities under conditions suitable for practical LCVD through systematic investigation of the deposition process itself and the reactivity of the laser-deposited films under idealized, ultra-high vacuum conditions. We have employed a combination of surface spectroscopies: multiple internal reflection Fourier transform infrared, temperature programmed desorption/reaction, laser induced desorption, and Auger electron spectroscopies and low energy electron diffraction.
KeywordsRefractory Metal Metal Carbonyl Temperature Program Reaction Ultrahigh Vacuum Condition Multiple Internal Reflection
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- 11.K.A. Singmaster, F.A. Houle, R.J. Wilson, Appl. Phys. Lett. Submitted, 1988. Google Scholar
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