Silicon deposition process

摘要

A step-wise process is disclosed for the efficient deposition of silicon. The process begins by reacting trichlorosilane and hydrogen on a heated substrate to deposit silicon. Silicon deposition efficiency of this reaction is determined by measuring the silicon to chlorine ratio in the deposition reaction effluent. The silicon-bearing effluent from the deposition reaction includes trichlorosilane, dichlorosilane, and silicon tetrachloride. The silicon-bearing effluent is collected in a first accumulator. The deposition reaction is continued using the collected quantity of silicon-bearing effluent together with an additional quantity of trichlorosilane as an input to the continuing reaction. The additional quantity of trichlorosilane is determined to make up the amount of silicon deposited in the previous step. The process is step-wise continued by measuring the silicon to chlorine ratio in the deposition reactor effluent, collecting an additional quantity of silicon-bearing effluent in a second accumulator, and using this silicon bearing effluent together with an additional quantity of trichlorosilane as an input to the reaction. In each step the ratio of silicon to chlorine in the deposition reactor effluent is measured and the amount of additional makeup trichlorosilane added to the recycled silicon bearing effluent is determined to supply a constant rate of silicon as input to the reaction. The step-wise reaction continues until steady state equilibrium is achieved.