TÜV certifies SST Hydrochlorination

Polysilicon production technology under scrutiny


SCHWARZE PUMPE, SAXONY -- Under observation of the team around Dr. Hartmut Neumann from TÜV Sued Industrieservice GmbH, the hydrochlorination process for the synthesis 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.  



Schmid Silicon Production Reaches Full Operation

With the successful start of production at the hydrochlorination plant for synthesis of trichlorosilane 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 Polysilicon. Jochen Schneider, CEO of SST, is very satisfied with the fast commissioning: „With the production start at the hydrochlorination plant we reached the last important milestone in the commissioning of our production plant after the "first Monosilane out" on May 16, 2011 and "the first Silicon out" on June 12, 2011.  As it was already announced in the press release of August 31,2011, at the same time an outstanding quality of Polysilicon was reached within this short period of time, which by far exceeds the current requirements for solar grade Silicon and even meets the high quality standards of the semiconductors industry".

The SST Monosilane-based Silicon Technology differs from the conventional production methods through its lean, improved process with an extremely low power and raw material consumption. Besides the resulting cost advantage of about 40% as compared to the Siemens technology and the highest product quality this production method is characterized by it’s more advantageous environmental balance. Schmid Polysilicon Production allows Schmid Silicon Technology to implement further improvements and thus creates a platform for development of new innovative Monosilane-based technologies, with some already being in the works.

As compared to the competition, the unique SST Hydrochlorination Technology is distinguished by a number of advantageous features. The Hydrochlorination Reactor is operated at a pressure of about only 10 to 12 bar. This results in a substantially reduced energy consumption required to achieve the pressure stage as well as in advantages when designing different pieces of equipment. At the same time lower pressure allows to significantly reduce deposits of e.g. metal chlorides. The SST Hydrochlorination Technology allows to equally using both silicon tetrachloride and hydrogen chloride gas as feedstock depending on the market situation.

Such intermediates as silicon tetrachloride, hydrogen chloride gas, and hydrogen, which emerge from the conventional Siemens CVD process, can also be directly processed to trichlorosilane and hence recycled in the SST Hydrochlorination.  

The operation of the own 94-strong workforce Polysilicon production plant provides Schmid Silicon Technology with a unique industry advantage.

SST Polysilicon Deposition Shows Outstanding Quality Results

Polysilicon complies with an "electronic grade" specification

Being the dominant raw material of the solar industry, Polysilicon must be of increasingly higher quality to meet the requirements for improvement in efficiency of multi- and monocrystalline solar cells. The demand for higher volume and more cost-effective production technologies has advanced the development of innovative purification methods of metallurgical silicon. 

An especially innovative technology in this field is offered by Schmid Silicon Technology GmbH (SST), which allows producing Polysilicon of the highest quality at a substantially reduced manufacturing cost due to its efficient process and very low power consumption.

Only two months upon the "first Silicon out" SST can now offer at its own production plant in Schwarze Pumpe, Saxony, featuring the Monosilane-based CVD deposition, Polysilicon, which already meets the requirements of the so-called "11N" material.  Herewith, the Polysilicon complies with an "electronic grade" specification and, thus, can be even used in the semiconductors industry.

The fast achievement of this quality provides another clear evidence for the advantage of the SST Monosilane-based technology vs. conventional Polysilicon production methods based on Siemens technology.

According to Jochem Hahn, COO of SST, these results come as no surprise, since through the disproportionation of trichlorosilane to monosilane alone this purification effect can be achieved easily and steadily due to the physical/chemical mechanisms.

Another milestone of this improved Polysilicon production technology is the achievement of the deposition rate on silicon rods of 1mm/h, resulting in low power consumption. Both results strongly confirm expected figures of SST technology, which herewith makes a substantial contribution to the overall cost reduction of up to 40%.