The chemical vapor deposition method using hydrogen radicals excited by microwave plasma has been applied to obtain silicon nitride (SiN) films of low hydrogen content. In this method, silane and monomethylamine were used as source gases. Various properties of deposited films such as the composition of SiN, the residual contents of carbon and oxygen, and the deposition rate were influenced by growth conditions. In the growth conditions, the distance between the center of the waveguide and the substrate was the most critical parameter because the distribution of the H radical strongly depended upon it in our experiment. For a suitable substrate position, carbon and oxygen contents could be reduced to a small value. On the other hand, residual hydrogen content was less than ∼1×1022 cm-3. This value was a quarter of that in the films grown by silane and ammonia gases under similar conditions.
Single crystalline 3C-SiC films were grown on a Si substrate by molecular beam epitaxy (MBE) using SiHCl3 and C2H4 gases. The optimal growth conditions were achieved at a growth temperature (Tsub ) of 1000 °C and a gas pressure ratio (PSiHCl3 /PC2H4 ) of 1/3 at PSiHCl3 =1×10−5 Torr. Prior to the essential growth of SiC, a carbonization process was performed with C2H4 gas only. A continuous observation by reflection high-energy electron diffraction (RHEED) was performed throughout the process of crystal growth. A series of RHEED patterns revealed that carbonization film could be grown at 750 °C and the lattice mismatch between Si and SiC crystals was satisfactorily relaxed. All processes of crystal growth were performed at a relatively low temperature.
Using the carbonization process, single-crystalline SiC films were grown at substrate temperature (Tsub) in the range of 750–1050 °C by the gas-source molecular-beam epitaxial method. This process was performed by using C2H4 gas and a special growth method in which the temperature was raised at a predetermined rate (RT) during growth. To realize the growth of single-crystalline carbonized films, it was found that a C2H4 gas pressure PC2H4=8×10−5 Torr and rising rate RT=25–25/3 °C/min were necessary. After the carbonization process, essential growth of SiC films using SiHCl3 and C2H4 gases in the range of gas pressure ratios PSiHCl3/PC2H4= (1)/(3) –5 (PSiHCl3=1–5×10−5 Torr) at Tsub=1000 °C was performed. In these all experimental ranges, single-crystalline 3C-SiC films could be grown.
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