Polysilicon Production Process: From Raw Materials to High-Purity Silicon

Polycrystalline silicon, also known as polysilicon, is a purified form of silicon. It is extracted from a rock called quartzite. It takes several raw material workflows to get to manufacturing polysilicon.

The global polysilicon market size is expected to reach USD 23.1 Billion by 2033, as per a Coherent Market Insights report. It is projected to scale rapidly at 8.4% CAGR over the forecast period (2026-2033). The purity of silicon is highly sought after by the IT sector due to its objective of attaining artificial super intelligence.

In this article, we look at the manufacturing process of polysilicon. We also take an in-depth look at the Siemens process, fluidized bed reactor (FBR) technology, and other polysilicon purification techniques.

Raw Materials and Initial Processing

Metallurgical-grade silicon (or silicon metal) or MG-Si is made from heating quartz (silicon dioxide) with a reactant that has access to carbon sources such as coal, wood, or charcoal in an electric arc furnace. The process extracts silicon dioxide, but the material produced is impure and inappropriate for high-tech applications.

Beyond the manufacturing process, developments in semiconductor fabrication are also influencing demand for polysilicon.

The high investment in the regionalization of semiconductor fabrication plants is expected to be a major driver of the polysilicon market. The potential of 5G and AI can drive the demand for polysilicon significantly. However, the high operating costs and large upfront capital required for its maintenance carries a huge risk.

Siemens Process: The Industry Standard

The most common polysilicon production method is called the Siemens process polysilicon method, in which sand-type silicon (Si) is sent to a fluidized bed reactor and reacted with hydrogen chloride to form trichlorosilane (SiHCl3), before being deposited as polysilicon. They are heated to 1,150 degrees Celsius until they are grown to polysilicon rods. This step is called chemical vapor deposition (CVD). These silicon rods are crushed into rocks or granules to be used in various applications.

The manufacture of consumer electronic devices such as smartphones and TVs requires polysilicon to produce chips. The high purity and electrical properties of semiconductors can drive its demand across high-technology sectors, providing an impetus to the polysilicon market till 2033.

Steps in the Siemens Process:

• Gas Production: In a high temperature process, metallurgical-grade silicon reacts with hydrogen chloride to produce trichlorosilane.
• Purity: Stripped of any foreign contaminant in the process, it reaches ultra-high levels of purity (over 99.9999%).
• Deposition: The purified trichlorosilane flows into a reactor where it is deposited layer by layer as heated rods initiate the deposition of silicon.
• Harvesting and Processing: When the rods have reached the correct diameter of thickness, they are harvested, crushed, and made ready for wafer production.

The Siemens process is energy-intensive, requiring large amounts of electricity and generating significant heat.

Fluidized Bed Reactor (FBR) Technology: A More Efficient Alternative

The fluidized bed reactor polysilicon process has attempted at reducing energy consumption. While the Siemens process requires rotating rods, FBR technology utilizes a small bed of silicon seed particles that are constantly fluidized by a stream of silane gas. The gas breaks down, and silicon materials deposits on the seed particles, gradually making them bigger.

The types of polysilicon grades produced are semiconductor grade polysilicon, solar grade polysilicon, metallurgical grade polysilicon, and others. By type, the semiconductor grade polysilicon segment is expected to account for 69.0% share of the market in 2026. The demand for advanced packaging for chips less than 10 nm in size can drive segment growth over the forecast period.

Advantages of FBR Technology:

• Use Less Energy: Need up to 90% less energy than the Siemen process.
• Production Efficiency: Unlike the batch processes, it can run continuously and lower operational expenses.
• Reduced Energy Efficiency: Lessens total costs as a result of enhanced energy effectiveness.

These efficiency benefits are also relevant as manufacturers face growing environmental requirements and demand from photovoltaic applications.

Compliance with environmental regulations to reduce carbon levels and improving the yield ratio of polysilicon chips can bode well for fab production hubs. By application, the photovoltaic segment is expected to lead the polysilicon market over the forecast period. The inclination towards renewable energy sources and government subsidies for bringing about a change in customer habits can bode well for the market.

Methods of Polysilicon Purification

The polysilicon these US producers plan to extract is highly pure and will be used for semiconductors and solar applications. Alongside chemical vapor deposition, which is applied inside Siemens and FBR methods, manufacturers have several polysilicon purification techniques;

• Directional Solidification: Controls crystallization and hence helps remove impurities
• Zone Refining: apply heating to separate and expel interfering elements.
• The second is the chemical etching which is used to remove surface contaminant layers from the finished polysilicon.

In addition to improving production efficiency, manufacturers use several purification techniques to achieve the required polysilicon quality.

By purification level, the ultra-high purity polysilicon segment is expected to dominate the market in 2026. The demand for microchips and the expanding electric sector is expected to provide new growth avenues.

Environmental considerations and energy consumption

Electricity usage for polysilicon manufacturing is a key concern especially as the world transitions to sustainable energy. Siemens process requires energy from 100-200 kWh/kg polysilicon.

Environmental issues include the following:

• High Carbon Footprint: In some regions, traditional polysilicon production depends on fossil-fuel-based energy.
• Toxic Byproducts: The process produces byproducts such as silicon tetrachloride, which must be carefully disposed of to avoid pollution.
• Water and Raw Materials Needs: Production requires a high consumption of water and raw materials.

Alongside these environmental considerations, regional policies and investments are also shaping the polysilicon market

The U.S. is expected to be a high growth region for the polysilicon market over the forecast period. Supportive government policies like the Inflation Reduction Act and state incentives to encourage fab production can bode well for the market. The demand for skilled craft workers and investment in advanced manufacturing methods can bode well for the market.

New Polysilicon Production Techniques

New technology enhances efficiency and sustainability in the polysilicon manufacturing process:

• Silicon waste recycling: Others retread silicon scrap to reduce waste.
• Integrating Renewable Energy-Solar and hydroelectric power are being adopted by more manufacturers.
• Novel Chemical Processes: New methods to lower harmful emissions and purify.

Tokuyama Corporation, GCL-Poly Energy Holdings Limited, Wacker Chemie AG, Hanwha Q CELLS, LONGi Green Energy Technology Co., Ltd., Daqo New Energy Corp, Hemlock Semiconductor Group, REC Silicon, SunEdison, JinkoSolar Holding Co., Ltd., and OCI Company Ltd are major players of the polysilicon market. New approaches to optimize costs of advanced material packaging and sourcing of raw materials at economical costs can bode well for market players in the long run.

Conclusion

It is a multifaceted process, a necessary step in the solar and semiconductor manufacturing process. Though the Siemens process continued to be the industrial standard, polysilicon technology with fluidized bed reactors was looking to make a name for itself with lower energy requirements. Ongoing innovations in polysilicon purification techniques and sustainability initiatives are positioning the industry for a cleaner, cheaper future.

The global polysilicon market is expected to thrive owing the adoption of new consumer electronic devices and advances in electronic engineering. The potential of microchips in medical, automotive, and renewable energy sectors can bode well for the market. Nearshoring or reshoring of the logistics of rare earths and minerals required in lowering raw material costs will be a key part of reassessment strategy of major players.