# Polysilicon: Production route

Hot rods versus floating granules: the race to cut power

Source page: https://www.materialinsights.org/chemicals/polysilicon/routes/

What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.

All routes start from metallurgical silicon and end with silicon above nine nines. The modified Siemens process, which grows rods from trichlorosilane in bell-jar reactors, makes about three-quarters of supply and all semiconductor grade. Fluidised-bed reactors (FBR) grow granules from silane or TCS with far less power and now make about a quarter of China's output, led by GCL. Upgraded metallurgical silicon is a cheaper, lower-purity route that faded. Semiconductor grade is a Siemens product with extra purification.

#### Routes compared

| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| **Modified Siemens process (rod polysilicon)** | about 76% of China's output (H1 2025, remainder after 24% granular) and nearly all output outside China | about 1.1 t silicon metal (indicative), 48-55 MWh electricity, about 8 t water and 2.3 t steam per t (industry average, 2025) | Tongwei over 900 kt, Xinte 300 kt, Daqo 350 kt capacity (2025) | not published | silicon tetrachloride (recycled), HCl | leading rod makers RMB 30-35/kg cash; Xinte RMB 26/kg; Daqo cash $4.46/kg (Q4 2025) |
| **Fluidised-bed reactor (granular polysilicon)** | about 24% of China's output (H1 2025), up from under 10% five years earlier; forecast 35% by 2030 | about 11-20 MWh electricity, 3-5 t water, 1.2-1.8 t steam per t | GCL 480 kt in Xuzhou, Leshan and Baotou; produced 269 kt in 2024 | over 97% total yield (H1 2025) | silicon fines, hydrogen | GCL cash cost RMB 25.31/kg (Q2 2025), the lowest reported |
| **Semiconductor-grade polysilicon** | about 3% by volume (derived); Wacker about 35% of the market | as Siemens, with more purification (indicative) | Wacker 20 kt; Hemlock (Michigan) about 20 kt (2025) | not published | off-spec material sold as solar grade | several times solar grade (indicative) |
| **Upgraded metallurgical-grade silicon (UMG)** | negligible today (indicative) | silicon metal and power (indicative) | small | not published | slag | low (indicative) |

#### How each route works
**Modified Siemens process (rod polysilicon)**

Ultra-pure TCS and hydrogen flow into bell-jar reactors where electrically heated silicon rods at about 1,100 C grow as silicon deposits on them over days. Off-gases are recovered and silicon tetrachloride is converted back to TCS. Rods are broken into chunks.

Proven, all purities; energy-intensive, leaders reach under 40 kWh/kg with a ceiling near 35.
 China Polysilicon 2026 report **Fluidised-bed reactor (granular polysilicon)**

Small silicon seed particles are suspended in silane (or TCS) and hydrogen in a heated reactor; silicon deposits on them as free-flowing granules. Granules suit continuous Czochralski recharging. GCL switched fully to FBR and exited Siemens in 2025.

About a third to a half the power of Siemens and lowest cost; purity concerns largely solved (over 96% meets n-type grade); REC Silicon exited FBR in late 2024.
 China Polysilicon 2026 report; PV Tech (Apr 2025) **Semiconductor-grade polysilicon**

A Siemens process with tighter distillation, cleaner reactors and etching to reach 10-11 nines and very low surface metals. Sold to wafer makers such as Shin-Etsu, SUMCO, Siltronic and GlobalWafers.

High margin, few qualified suppliers outside China; tiny volume.
 China Polysilicon 2026 report **Upgraded metallurgical-grade silicon (UMG)**

Silicon metal is refined directly by slag treatment, directional solidification and vacuum refining, skipping the chlorosilane step.

Cheap and low energy; purity too low for modern n-type cells.
 Indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.

## Other sections

- [Summary](https://www.materialinsights.org/chemicals/polysilicon/index.md)
- [Overview](https://www.materialinsights.org/chemicals/polysilicon/overview/index.md)
- [Correlation](https://www.materialinsights.org/chemicals/polysilicon/correlation/index.md)
- [Production](https://www.materialinsights.org/chemicals/polysilicon/production/index.md)
- [Feedstocks](https://www.materialinsights.org/chemicals/polysilicon/feedstocks/index.md)
- [Cycles](https://www.materialinsights.org/chemicals/polysilicon/cycles/index.md)
- [Trading](https://www.materialinsights.org/chemicals/polysilicon/trading/index.md)
- [Movement](https://www.materialinsights.org/chemicals/polysilicon/movement/index.md)
- [Regulation](https://www.materialinsights.org/chemicals/polysilicon/regulation/index.md)
- [Characteristics](https://www.materialinsights.org/chemicals/polysilicon/characteristics/index.md)
- [Emissions](https://www.materialinsights.org/chemicals/polysilicon/emissions/index.md)
- [Relationships](https://www.materialinsights.org/chemicals/polysilicon/links/index.md)