Polysilicon production technology under scrutiny
Under observation of the team around Dr. Hartmut Neumann from TÜV Sued Industrieservice GmbH, the hydrochlorination process for thesynthesis of trichlorosilane at the production plant of Schmid Silicon Technology in Saxony, Dresden has been tested for its conversion rate in December 2011.
The study was done under exceptional conditions: The operating parameters were lowered to the minimum settings in order to verify which is the absolute minimum conversion rate for the hydochlorination system under worst operating conditions. Accordingly, the hydrochlorination plant was running at only 50% of its nominal throughput in respect to STC consumption, and the reaction time of the fluidized bed reactor was reduced to 60%. Also, the reaction temperature was set to a minimum.
Considering that the plant has been running with minimal process parameters, an impressive conversion rate of 24.3% was achieved. Jochem Hahn, COO of SST: “We are very proud to prove to the polysilicon world the effectiveness of our low pressure hydrochlorination system. Our state of the art low pressure hydrochlorination serves a lot of advantages to our customers in respect to operation, safety and cost compared to conventional high pressure systems.” Since polysilicon manufacturers need the flexibility to adjust their production output according to the market conditions it’s important for them to know the performance of the plant if running at reduced capacity.
The TÜV experts also confirm in the certificate that operating the hydrochlorination plant at full capacity with normal temperatures and under normal conditions will enhance the conversion rate of STC, and therefore the output of TCS, significantly. Jochem Hahn, COO of SST: “We are able to confirm a 26.8 % conversion rate in production with an even further upside potential.”
With the start of production of the hydrochlorination plant in September 2011, Schmid Silicon Technology within just 4 months successfully completed the commissioning of its own monosilane-based production facility for polysilicon manufacturing. Herewith SST closes the entire production cycle beginning from metallurgical silicon and ending with high-purity, 11N electronic-grade polysilicon.
