The technology of purification of solar grade polysilicon can be classified into two methods: the chemical method and the physical method. For chemical method it is necessary for silicon to be converted into an intermediate product of silicon compounds in the purification process of silicon. And then silicon compounds are converted to high-purity polysilicon using pyrolysis or oxidation-reduction reaction.

Physical method is also known as physical metallurgy method. In this method impurities are removed by the use of physical or chemical methods in the condition of not changing the nature of the metallurgical grade silicon. Although chemical reaction are still involved, its response objects are boron, phosphorus and other impurities and silicon does not change its chemical nature. Due to its low cost purification of physical purity is considered as a rising star to replace the high-purity polysilicon though has its limits.

However because chemical method involves cumbersome control and processing of intermediate products , high technical difficulty, and various costs according to different sources of technology has higher cost than the physical way in general though it can produce high purity polysilicon. Most of the chemical methods are subject to the use of metallurgical grade silicon as raw material for silicon compounds, and few are prepared for direct use of silica-silicon compounds.

In chemical methods, Siemens process is widely used for the early production of semiconductor grade polysilicon in the industry. It is a mature technology but the cost was relatively  high. In addition to Siemens process, there are ASiMi method, fluid bed reactor method and tubular deposition method, etc.

ASiMi method, developed by Advanced Silicon Material (ASiMi) Company ,is a technology of producing  high purity polycrystalline silicon  using silane / SiH4 as the raw material . In 2005 ，ASiMi announced its withdrawal from polysilicon market and the majority of the stock was purchased by Norway's REC (Renewable Energy Corp), so this technology is still conducting in REC currently.

As ASiMi method, fluid bed reactor method also uses the silicon methane as raw material. This method can reduced nearly 30% of electricity consumption because of low reaction temperature. And this method solves the problems of slow deposition in ASiMi method as large reactions area of silicon and faster air flow in the reactor. Fluid bed reactor is superior to Bell-shaped Siemens reactor due to its using for continuous production.

Tubular deposition method, as a polysilicon production technology used by Joint Solar Silicon GmbH (JSSI), is built on the same principle and requires the same raw materials as fluid-bed reaction which generates polysilicon by running thermal decomposition of silane/SiH4and hydrogen gas. JSSI declared that this method consumed one tenth of electricity of the traditional Siemens method and the conversion rate was up to 95 ~ 98%.There have already been the production records.

Physical metallurgy method for generating solar polysilicon was first applied in 2008 with a small amount of output. Purification of solar-grade silicon by this method also requires metallurgical grade silicon with low impurity as raw material, and then goes through several processes to complete.

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In addition, some companies employ other methods of purification for mass production which are still in research and development stage, such as sodium reduction and thermal carbon reduction method. Without having the process of metallurgical grade silicon, its raw materials such as sodium fluoride is a by-product of fertilizer, while the sodium silicate can be directly derived from the chemical reaction of silica.

Overall, for successful mass production main approach of purification of solar grade polysilicon at present are Siemens process, fluid-bed reaction, tubular deposition method and the ASiMi method. Although physical metallurgy method has a small amount of output in 2008, the quality is still unstable and the entire technology still has room for improvement.  It has been officially listed as one of the options of the source of solar energy materials. In recent years, many companies claimed to use other methods for mass-production. Without consistent quality, strict evaluation in recording relevant mass-production is needed when it comes to whether to put investment to the relevant technologies or to use products in large-scale.