1. Overview of the Production of Silicon William Dulaney CMEN 413
2. Polysilicon, which is used by the semi-conductor industry, is an extremely high purity silicon (impurities in the ppb-ppt range). At least 60% of the polysilicone produced is by the Siemens process. This batchwise process was developed in the 1950’s, and is based on the thermal decomposition of trichlorosilane, 2SiHCl3, at very high temperatures. The Silicon is deposited on to a rod inside of a deposition chamber. Production of Polysilicon Luque, A., & Hegedus, S. (2003). Handbook of Photovoltaic Science and Engineering. Hoboken: John Wiley & Sons.
3. The feed for the Siemens process is: MG-Si, Metallurgical Grade Silicon Dry HCl 3 separation processes 2 simultaneous distillations (purification of TCS) 1 Gas recovery separation and purification 2 reactions processes Hydrochlorination of Si in fluidised bed reactor Pyrolysis in Siemens reactor Production of Polysilicon Luque, A., & Hegedus, S. (2003). Handbook of Photovoltaic Science and Engineering. Hoboken: John Wiley & Sons. TCS: Trichlorosilane TET: Tetrachlorosilane
4. Production of Polysilicon Luque, A., & Hegedus, S. (2003). Handbook of Photovoltaic Science and Engineering. Hoboken: John Wiley & Sons. TCS: Trichlorosilane TET: Tetrachlorosilane
Editor's Notes
Polysilicon, which is used by the semi-conductor industry, is an extremely high purity silicon (impurities in the ppb-ppt range).At least 60% of the polysilicone produced is by the Siemens process.This batchwise process was developed in the 1950’s, and is based on the thermal decomposition of trichlorosilane, 2SiHCl3, at very high temperatures.The Silicon is deposited on to a rod inside of a deposition chamber.
The feed for the Siemens process is:MG-Si, Metallurgical Grade SiliconDry HCl3 separation processes2 simultaneous distillations (purification of TCS)1 Gas recovery separation and purification2 reactions processesHydrochlorination of Si in fluidised bed reactorPyrolysis in Siemens reactor
First, MG-Si and dry HCl are fed into a fluidized bed reactor. The product of this step is TCS with a byproduct of TET. Since TET is not wanted, a separation process is used to separate the two components. Distillation is the method used to separate TET and TCS, and it is done twice consecutively. The product stream after two separate distillations is called “Hyper-Pure TCS”. The pure TCS is then fed into the Siemens reactor along with H2 gas. Pure polysilicon is deposited onto a rod inside of the reactor, while the gas mixture is taken away for recovery and purification.
