Trichlorosilane

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Trichlorosilane (TCS) is considered the foundation molecule for the semiconductor industry. It is the raw material that becomes silicon for silicon wafers, which most integrated circuits are built upon. In addition, it is the raw material to produce dichlorosilane (DCS), monochlorosilane (MCS) and silane. These chlorosilanes are, in turn, the primary feedstock to produce aminosilanes, with silane being the raw material for disilane production. 

At a commercial scale, TCS is produced by three methods:

  1. Hydrochlorination (fluidized bed reactor):
    Si + 3SiCl4 + 2H2 → 4HSiCl3

  2. Chlorination (fluidized bed reactor):
    3HCl + Si → HSiCl3 + H2

  3. Hydrogenation (thermal converter):
    SiCl4 + H2 → HSiCl3 + HCl

A single polysilicon production plant can use a combination of these methods to optimize the overall process.  In the fluidized bed processes, metallurgical silicon is reacted with a chlorine source to yield TCS. The process presents unique challenges as the silicon particles are consumed in the chlorosilane environment at elevated temperatures and pressures.  The velocity and internal components (distributors, bubble breakers and cyclones) are optimized to increase conversion, reduce energy consumption and minimize waste.  

The thermal converter technology is a gas phase reactor utilizing advanced heat exchange techniques and graphite parts to optimize the process. State-of-the-art converters are purpose built and have competitive energy usage per kilogram of TCS produced compared to the fluid bed process.  

Ultra-high purity TCS is required for the production of silicon.  Trichlorosilane is purified using a combination of distillation and fixed-bed adsorbers. A properly designed system will produce TCS with ppt levels of boron and phosphorus with carbon levels less than the detection limits. Metals and other contaminants are also typically less than the detection level.

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AMS experience/core competence in the area

AMS has the most advanced technology for TCS production.  Employed in more than ten polysilicon plants, it has been in commercial operation for over a decade. AMS has experience designing, fabricating and operating fluid bed reactors ranging in diameter from 1 m to greater than 4 m.   

AMS’s technology pioneered the use of standalone STC vaporizers and the simultaneous heating of hydrogen and STC.    

We have experience with the design and operation of purification systems processing hundreds of thousands of tons of TCS per year.

AMS Product Offering

AMS offers a full suite of products and services for the production of high purity TCS. We provide a customized approach to meet the needs of our customers.  Solutions can range from basic designs to turnkey heating systems and fluidized bed reactors. With these solutions AMS can provide value to all TCS producers. Patents

Our latest technology produces enough TCS, in a single fluidized bed reactor, to manufacture more than 20,000 metric tons per year of polysilicon making it the largest available in the industry. Our technology has been developed over more than a decade with three generations of reactors in operation:

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  • Generation 1: Designed in 2008 and implemented 2010

  • Generation 2: Designed in 2010 and implemented 2012

  • Generation 3: Designed in 2015 and implemented in 2017

  • Generation 4: Current state-of-the-art

Our advanced trim heater can effectively heat hydrogen and STC to over 580oC in a compact footprint with a high reliability.

We specialize in optimization of existing systems. For example, debottlenecking of Polysilicon plants is often limited by increasing STC conversion/TCS production. Addition of fluidized bed reactors and associated equipment are expensive with long project schedules.

With proven plant data, our thermal converters can convert tens of thousands of tons of silicon tetrachloride per year and can be integrated into existing facilities for efficient debottlenecking. AMS’s thermal converter can be integrated into an existing hydrochlorination facility to increase the capacity of the plant by 60% using less capital compared to adding another fluid bed reactor.