Details

Autor(en) / Beteiligte

• SEAWARD, KAREN L

Titel

SPUTTERING SILICON-CARBIDE THIN FILMS WITH SURFACE MOBILITY ENHANCEMENT (SEMICONDUCTOR, SINGLE-CRYSTAL, HIGH TEMPERATURE)

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

1984

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Silicon carbide is a wide band gap semiconductor and the cubic zincblende form (beta-SiC) is of interest for high power, high temperature microelectronic applications. Synthesis of device quality SiC has been difficult, primarily because its decomposition temperature is 2700(DEGREES)C. Good epitaxy (generally a condition for single-crystal growth) is usually achieved above 0.65Tm, which for SiC would be 1930(DEGREES)C. In this work, a low temperature approach was taken by way of magnetron sputtering at 800(DEGREES)C onto silicon and sapphire. After comparing epitaxial systems of noble metals, refractory metals and semiconductors, one limitation for epitaxy of high temperature semiconductors was found to be low surface diffusivity of atoms. In order to synthesize single-crystal SiC thin films, methods were pursued to increase the mobility of species arriving at the deposition surface. The major focus was on the use of an adsorbed layer to enhance the surface mobility of diffusing atoms. This phenomenon has been demonstrated in numerous adsorbed-metal/metal systems which have been studied by field ion and electron microscopies and by grain boundary grooving. Tin was chosen as the material for the mobile adsorption layer to be generated either by cosputtering or by evaporation during the sputter deposition of SiC. Relative tin-to-SiC deposition rates were investigated over the range 0.2 - 6.8. For deposition at 800(DEGREES)C, cosputtered tin (i) increased the crystalline perfection of SiC sputtered onto (111) silicon; (ii) changed the orientation from (111) to (110), increased the degree of orientation and decreased the grain size of SiC on (1(')102) sapphire; and (iii) had no effect on the structural nature of depositions onto (0001) sapphire, which were of the highest perfection. This dependence on substrate was related to the deposition surface which was (i) nonuniformly converted to SiC in the silicon case; (ii) of improper symmetry in the (1(')102) sapphire case; and (iii) of correct symmetry with (0001) sapphire, since beta-SiC (111) texture is energetically favored. Evaporation of tin while sputtering decreased the crystalline perfection of SiC depositions and this was attributed to an increase in contamination from the evaporation source. In the best cases, single-crystal thin films of SiC containing low angle mosaic boundaries were formed on (0001) sapphire with sheet resistivities in the 200 ohm-cm range.