January, 2007: An announcement by Tokuyama Corp. that a planned 3,000 ton silicon factory using Siemens reactors will be dedicated mainly to production for the semiconductor industry does not mean the Japanese company has given up on its Vapor to Liquid Deposition (VLD) process for low-cost solar-grade silicon, says a company representative.

		© Norbert Michalke / photon-pictures.com
	Still in pilot phase: Tokuyama‘s Tamura says research continues on commercial production of VLD solar-grade silicon.

According to a Dec. 8 press release, a new ¥45 billion ($387.5 million) factory will be completed at the company‘s Higashi plant in Shunan City in spring 2009 with 2,500 tons going to semiconductors and just 500 tons to solar cells once full production capacity is reached. But Naoki Tamura, manager of Tokuyama‘s polysilicon sales department, says the company is continuing its research work on VLD technology.

Tokuyama, which claims that the VLD has a silicon precipitation rate 10 times higher than in Siemens reactors, presented the technology to the public for the first time at PHOTON‘s 1st Solar Silicon Conference in 2004 (see PI 6/2004, p. 36). In 2006, after starting a 200 ton pilot production plant, Tokuyama decided to delay commercial VLD production until late 2008 (see PI 5/2006, p. 26). »The plant capable of 200 tons per year is still in the validation phase for commercial production,« says Tamura. »The results have not yet hit our target.« Tamura would only say that »some issues« still need to be settled, without indicating whether commercial production would still begin as scheduled.

The press release says that since demand for solar cells has led to a tight silicon market, and because »demand for semiconductors is expected to be greater,« Tokuyama has decided to »contribute to a stable supply« by expanding production facilities. The company says when the factory is completed its annual polycrystalline silicon capacity will be 8,200 tons. According to estimates in an April 2006 silicon report by Citigroup, Tokuyama had a total production capacity of 5,200 tons in 2005, increasing to 5,400 in 2006, while the portion dedicated to solar rose from 1,400 tons to 1,560 tons during the same period.