Filament Production System

Filaments and Their Role in the Polysilicon Plant

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

The filaments, either square or round, are long slender silicon rods. 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 on the CVD baseplate. Each pair of filaments are connected by an additional silicon 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, forming a polysilicon U-rod.

Filament Production Processes

Silicon filaments can be produced typically by three different methods:

• In the first process, 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.
• In the second process, filaments are sawn (cut) from large polysilicon rods, deposited in a CVD reactor.
• In the third process, filaments are cut from large diameter, long silicon ingots grown in Czochralski (CZ) crystal growth furnace pullers using chunk polysilicon.

In all three techniques, filaments can be doped or undoped.

What PPP Offers

Poly Plant Project, Inc. offers a seamlessly integrated solution for filament production meeting your plant’s annual demand for polysilicon production. PPP’s offering includes the following:

• Fully integrated technology package, providing complete engineering, design and process information required 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 work with you to supply filaments if you do not wish to invest in the construction of an in-house filament production facility.

Why Work with PPP

• PPP offers fully integrated, one-stop solution for all your filament production needs
• PPP’s equipment and technology ensure timely and cost effective filament production, reducing downtime and production cost
• PPP’s production process and advanced equipment ensure production of filaments of the purest quality, without contamination related issues
• PPP offers technology for doping filaments
• PPPP’s automated filament handling machines produce straight and robust filament with minimal incidence of breakage, kerf loss, and material wastage. Thereby ensuring efficient polysilicon production while reducing overall production costs