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Filament Production System

Filaments and Their Role in the Polysilicon Plant

The silicon filament is one of the key components required in the production of polysilicon. Electrically heated silicon filaments are used in the Chemical Vapor Deposition (CVD) reactors as the starting material (seed) for the trichlorosilane (TCS) decomposition process.

The filaments are long slender silicon rods that can either be square or round cross section. The filaments are loaded into a CVD Reactor by securing one end of each filament into a graphite chuck which sits atop an electrode mounted in the Reactor’s baseplate. Each pair of filaments is connected by an additional filament section called a bridge. A pair of filaments joined by a bridge is called a U-rod.

During the deposition process, the TCS gas is decomposed uniformly around the filaments, which grow into polysilicon U-rods.

Filament Production Processes

Silicon filaments are typically produced by one of these three methods:

  • Growth Method - Small diameter crystalline rods (slim rods) are grown from polysilicon rods (source rods) in specially designed float zone crystal growth furnaces. Several slim rods can be grown from one source rod.
  • Cut Method - Filaments are sawn (cut) from large polysilicon rods, deposited in a CVD reactor.
  • Puller Method - Filaments are cut from large diameter, long silicon ingots grown in Czochralski (CZ) crystal growth furnace pullers using chunk polysilicon.

In all three of these methods the filaments can either be doped or undoped.

What PPP Offers

Poly Plant Project offers a seamlessly integrated solution for filament production enabling plants to meet their annual demand for polysilicon production:

  • Fully integrated technology package providing complete engineering, design and process information to produce polysilicon filaments and bridges for polysilicon production
  • Complete plant and equipment layout design
  • Supply of all major equipment including Czochralski pullers, polysilicon rod cropping machine, filament cutting machine, filament and bridge grinding machines, etching/cleaning bench, annealing furnace and other associated equipment
  • Equipment installation support
  • Commissioning, startup and training support
  • Equipment servicing and maintenance

PPP can also supply filaments if you do not wish to invest in an in-house filament production facility.

Why Work with PPP

  • Fully integrated, one-stop solution for our customers’ filament production needs
  • Equipment and technology delivering cost effective filament production, while reducing downtime and production costs
  • Production processes and advanced equipment ensure high-purity and no contamination issues
  • Process technology for doping filaments
  • Automated filament handling machines produce straight and robust filaments with minimal incidence of breakage, kerf loss, and material waste.

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