Interesting article about making SOI wafers

  • Thread starter Thread starter YKhan
  • Start date Start date
johnno said:
Wow. I can see why Intel don't want to use SOI - $1000/wafer vs $300. That
is a massive chunk of wafer cost. Or maybe they were comparing 300mm SOI
wafers with 200mm normal wafers.
Click to expand...

Yeah, that cost sort of surprised me too. However, I don't think that's
the cost of a 300mm wafer, that's probably the cost of 200mm wafers. I
had heard somewhere that the cost of a 300mm wafer is about $5000! And
I'd assume that that means non-SOI 300mm. If the cost of converting
natural to SOI wafers is a fixed cost, then a $5000 wafer would go upto
$5700 (i.e. additional $700). If the cost is proportional to the area
of the wafer, then the cost will go up by $1400 -- 300mm wafers have
double the area of 200mm ones. In either case it looks like the
proportionate cost increase of natural vs. SOI is much lower with 300mm
than with 200mm.

Yousuf Khan
 
Yeah, that cost sort of surprised me too. However, I don't think
that's the cost of a 300mm wafer, that's probably the cost of 200mm
wafers. I had heard somewhere that the cost of a 300mm wafer is about
$5000! And I'd assume that that means non-SOI 300mm. If the cost of
converting natural to SOI wafers is a fixed cost, then a $5000 wafer
would go upto $5700 (i.e. additional $700). If the cost is
proportional to the area of the wafer, then the cost will go up by
$1400 -- 300mm wafers have double the area of 200mm ones. In either
case it looks like the proportionate cost increase of natural vs. SOI
is much lower with 300mm than with 200mm.
Click to expand...

$5000 for a processed 300mm 90nm wafer sounds about right to me, maybe a
bit high, but I'm only familiar with 200mm, and .18um at that.
But we're still looking at either 14% or 28% increase in wafer cost -
either way it makes a big dent in your margins.
 
$5000 for a processed 300mm 90nm wafer sounds about right to me,
maybe a bit high, but I'm only familiar with 200mm, and .18um
at that. But we're still looking at either 14% or 28% increase
in wafer cost - either way it makes a big dent in your margins.
Click to expand...

Some perspective? A 300mm wafer should yield about 500 dice
(100mm2 ea, incl kerf & layout losses). So that's $10/ea, multiplied
by some yield factor. 28% is $2.80/CPU -- say 3% on $100 ASP.

I wouldn't call that a big dent unless your yields are < 60%

-- Robert
 
Back
Top