Until now phosphorous doping of solar cells had to be done in a non-continuous process in a horizontal tube furnace or in a special conveyor furnace, says the company. The horizontal furnaces need a large footprint and much time for loading and unloading is used. On the other hand, the conveyor furnaces cannot work with doping gas. Additional process steps like printing a doping paste on the wafers and removing it after thermal treatment are necessary.
As the first furnace manufacturer, now Koyo Thermo Systems merged the benefits of both systems and developed a continuous tube furnace which can use POCl3 doping, has a low foot print, high throughput, low energy consumption and reasonable price.
Today Koyo Thermo Systems presented this brand new furnace at the solar exhibition PVJapan 2010 in Yokohama. Koyo expects, that this new model will be a "breakthrough in doping technology". This furnace, continues the company, can help to reduce production costs of crystalline solar cells further and this is a key issue in the development of alternative energies and it can be used also for doping of semiconductor wafers in IC manufacturing.
Koyo had done pioneering work for doping solar cells before already. A modified conveyor furnace with wire transportation system had been developed, which could offer an improved temperature uniformity during doping and same time reduce energy consumption, compared to the conventional mesh belt transportation furnace.
