6 inch InP wafers cut device costs

17 Jun 2002

The first ever 6 inch InP wafers have been made by Japanese company Showa Denko.

Courtesy of Compound Semiconductor magazine.

Showa Denko (SDK) of Japan has developed the world's first 6 inch InP wafers, enabling device manufactures to fit twice as many devices on a wafer when compared with conventional 4 inch wafers.

Already shipping sample quantities, SDK plans to start volume production later this year.

SDK makes the 6 inch wafers using a proprietary hot wall liquid encapsulated Czochralski (LEC) method. According to Takayuki Sato, the marketing manager of compound semiconductor materials at SDK, growing 6 inch wafers in this way has posed some fabrication problems.

"There are more difficulties in growing 6 inch boules compared to 4 inch boules and it is very important to maintain thermal stability during crystal growth," he said. "We are continuing to adjust the growth conditions to improve the crystal quality and have achieved dislocation densities of 1 x 105 per sq cm." This is comparable to the dislocation density of currently available wafers.

SDK hopes that its latest wafers will become the material of choice for photodiodes in 40 Gbit/s fiber-optic communication systems and believes that by 2005 the wafers will make up to 10% of its total InP wafer and epiwafer sales.

"Some of our customers have already asked us to provide them with 6 inch wafers," said Sato. "And while we suppose that the volume of wafer demand will be relatively small over the next two years, we expect growth in the future."

Sato also believes that the upgrading of equipment from 4- to 6 inch by chip makers will not hamper demand as many device manufacturers, particularly in the US and Taiwan, already have 6 inch fabrication lines for GaAs devices.

"We have a plan to start volume production by the end of the third quarter of 2002," he concluded. "Production capacity will be around 500 wafers a month and because we have a compatible process between 6- and 4 inch we will be able to adjust the volume of our production according to the customer's demand."

Author
Rebecca Pool is features editor of Compound Semiconductor magazine.