Pt and ALD
mcvittie at snf.stanford.edu
Thu Jan 26 09:39:25 PST 2006
The ALD system was put together to deposit gate dielectric materials. As such,
it has to be clean enough to allow exiting wafers into tool, such as LPCVD poly
Si and the 4108 RTA, without cleaning. Note HF removes Al2O3. A tremendous
effort was made by me to clean up the Ald system to the point that it is a
clean tool. In particular, every line, valve and surface coming in contact
with the process gases where either chemically cleaned or replaced. Since this
cleaning, all questionable wafers to be run in the tool have gone through
surface analysis so we could see what trace metals were on them. Metals, such
as Pt, Pd and W, are not a big concern since they do have deep levels. Trace
metals, such as Cu, Na, K, Mn, Au, etc, are of concern.
We should have the same rules for the Ald system as we have for other clean
tools as to when we require surface analysis for wafers from the outside.
Ed Myers wrote:
> SpecMat members,
> I have done some searching regarding the request from Phil Barth to run Pt
> through the ALD system. The communications I found do not show Intel
> running metals through the system. I did find a series of request for
> running Pd-Si-O in some of our clean equipment. If we do allow Phil to run
> Pt in the ALD, it most likely will be the first SemicleanB material in the
> I looked up the deep levels for Pt. They are similar to W, which is one of
> our 3 acceptable metals (Al, Ti and W). The deep levels are:
> 0.25 and 0.39, acceptors and 0.18 and 0.30, donors
> Tungsten is: 0.22, 0.30, 0.37, 0.55, acceptors and 0.31 and 0.34, donors.
> (of course these values depend on which data you use)
> My recommendation is we allow noble metals such as Pt and Pd (not gold) in
> to the ALD.
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