I have recently started working on application of SiC technology in VLSI application, but unfortunately I couldn't find much literature avilable on internet. It would be grateful if any one can help me out on finding them or giving me guidence.
Is that even possible? The defect density of SiC is so high it's hard to make reliable diodes out of the stuff.
John
You haven't been keeping up, John. Cree research has an ad on page 12 of the June issue of Power Electronics for their Schottky diodes. Very nice specs:
June issue
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, have been in the labs and journals for years but are still not commercially feasible.
Infineon has a few nice parts, high voltage but low junction capacitance.
Some people are starting to make SiC fets, too. They're more like tubes, high-voltage, depletion mode, huge pinchoff voltages. Leaky as hell.
John
the June issue
Didn't you see the 1200 volt parts on that page?
the June issue
Yup, screaming progress. I think they're up to using 2" wafers now.
John
On Sat, 30 Jul 2005 16:43:47 -0700, John Larkin
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!
Oh, don't get me wrong, I've been eagerly waiting for kilovolt SiC schottkies and high-voltage mesfets (dare I hope for phemts?) for years now... many years now. It's just that deliveries have lacked promises by 10 years on average, which slows down the design cycle some. I designed in some hv SiC schottkies about 5 years before I actually got any that would work (we based our designs on Motorola and Microsemi datasheets, none of which became real parts.) We're currently using three Infineon 400 volt SiC schottkies in series to get the high voltage and low capacitance we need.
TI sampled us some wonderful SOT-89 mesfets, Idss = 7 amps, but bailed on production. It must be tough working with compound semiconductors.
The specs I've seen on SiC and GaN mesfets have been discouraging, too. Huge pinchoff voltages, high capacitances, stuff like that.
Oh well, in another 10 years...
We're very lucky that silicon exists.
John
How long has it been since you got those parts? The Infineon web site
Given how long it has taken to get real SiC parts, how long till we get diamond Schottkies? :-)
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