[labnetwork] Bosch etch foreline and pump powder residue question...

[John Shott]

Bob:

This is a good point that reminds me of minor etch modifications that 
our etch guru Jim McVittie made me aware of:

> John,
>
> The STS process engineer from the factory who trained me on STS2 said that they gone to adding some O2 to the etch steps on there old tools to solve the vacuum line deposition problem. We never went that way because it meant that we would have to recharacterize our processes on the STS1 and no one wantd to do it. The Berkeley folks published a paper on adding O2.  Jim
I'm hopeful that someone from Berkeley can provide a better reference 
and comment on this approach, but I believe that folks have found that 
adding modest oxygen flow (~10%, as I recall) during the etch step helps 
to reduce polymer buildup without significantly affecting etch rates and 
other process parameters.

Thanks,

John


On 11/5/2013 2:16 PM, Bob Henderson wrote:
> Has anyone considered using an oxygen/fluorine plasma for removal of 
> the polymer. Since most DRIE systems have an ICP source a fair amount 
> of O/F will be generated that can be used to etch away the carbon rich 
> polymer maybe as far as the gate valve and turbopump. The reactive 
> species probably won't have a lifetime that will extend very far down 
> the foreline but I have seen downstream plasmas that will go a few 
> feet into the foreline before extinguishing. Bob Henderson

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