Re: SiC Technology

On Sat, 30 Jul 2005 16:43:47 -0700, John Larkin
>>>I've used them, and some GaN parts, too. But it was/is very hard to
>>>make reliable diodes from SiC, and they were actually available years
>>>after they were announced, due to fab problems. Higher-voltage parts,
>>>up to 1400v maybe
>>
>> Didn't you see the 1200 volt parts on that page?
>>
>
>
>Yup, screaming progress. I think they're up to using 2" wafers now.

I think you're being overly pessimistic about them. From their 1999
Annual Report:

"The wafer business was a solid performer this year as worldwide R&D
and production drove sales higher. Also the materials business
targeted for gemstone applications enjoyed a significant year of
development and revenue growth. During this past fiscal year, Cree has
dramatically improved yields of the silicon carbide crystals supplied
to C3. In addition to improving the yields, Cree has been driving to
increase the size of the crystals enabling C3 to potentially increase
the number of moissanite gemstones available for distribution. As a
result of our development of three-inch size crystals, Cree will
gradually migrate to the larger three-inch size wafers for LED
production which will increase the number of LED chips available for
shipment later this fiscal year."

So they were up to 3" wafers a while ago.

>From the 2004 Annual Report:

"Over the past few years, we have continued to expand our product line
of three-inch wafers, which are better suited for the manufacture of
power and microwave devices. We continue to develop SiC wafers that
are larger and of higher quality."

In the 2004 report, they say that sales of wafers were 11%, 9% and 7%
of revenue for 2002, 2003 and 2004, respectively. Sales of LEDs
increased over the same time period.

About 2% of revenue came from sales of bulk SiC crystals for gemstone
use (moissanite).

Sales of LED's represented 78% of revenue in 2004, but power
semiconductor devices only generated 1% of revenue.

So, maybe as the production of 3" wafers increases, we'll see more
power semiconductor devices. I'd like to see a SiC power FET. I
remember a description from them some years ago in one of the IEEE
journals of a power FET that could operate at 350 degrees. It
wouldn't take much of a heat sink to get rid of a lot of heat at that
temperature!

>
>John

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