Production Technology Co-Development
of Chisso Solar-grade Silicon

Chisso Corporation

Nippon Mining Holdings,Inc.

Toho Titanium Co.,Ltd.

 

 

 

Chisso Corporation (Headquarters: Otemachi, Chiyoda-Ku, Tokyo; President/COO: Shun'ichi Okada,) Nippon Mining Holdings, Inc. (Headquarters: Toranomon, Minato-ku, Tokyo; President/Representative Director: Mitsunori Takahagi,) and Toho Titanium Co., Ltd. (Headquarters: Chigasaki, Chigasaki City, Kanagawa; Corporate Officer: Kazuharu Nogami) have agreed to conduct a study together that will establish the technology for the production of polysilicon for photovoltaic power generation by zinc-reduction method (Chisso Solar-grade Silicon Technology, hereinafter referred to as "CSS".)

The companies will further deliberate upon the conclusion of the joint venture contract for the establishment and launch of a new company.

 

CSS transacts business in chlorination, reduction and electrolytic reaction. In this technology, silicon tetrachloride produced by the chlorination reaction of metal silicon is reduced by zinc to produce 6N grade polysilicon (99.9999%). The polysilicon specified for the photovoltaic generation purpose is used as the raw material of Crystalline Silicon Solar Cells.

 

Chisso Corporation and New Energy and Industrial Technology Development Organization (NEDO) have been engaged with the research and development of CSS since 2002.  Upgrade from the bench-scale laboratory to a pilot plant is currently scheduled at Minamata Research Center (Minamata City, Kumamoto.)  The chlorosilane production technology that is applied in the chloridation process is currently operated by Chisso.  It follows the legacy of Japan's first high purity silicon technology for the semiconductor purpose that was offered by Chisso in the 1960s.　

The core technology developed by Chisso will be fused with the electrolytic technology for the metal titanium production that Toho Titanium has accumulated over the years and the high purity metal technology of Nippon Mining Holdings Group.

 

CSS also employs a closed loop system.  It cyclically utilizes zinc chloride, which is a side-effect of the reduction process, to reduce costs and to enhance the production of high quality polysilicon while greatly reducing the by-products.