Hi,

I had the same troubles with ICP etching and grease. The first idea was to
carefully clean the substrates with hot piranha, in some case it works.

You can also get rid of the grease and stick your wafer directly on the
carrier one using the photoresit and try to lower the backside
temperature. I had also tried not to stick the two wafers, but simply put
them into conctact, if you are not afraid about opening your chamber to
take back the wafers in case of sliding.

Alexandre



> Hello all,
>
> Some colleagues of mine have been doing some ICP silicon etching and
> have come across a major issue.
>
> They use small substrates which have to be attached to a 4 inch silicon
> carrier wafer. The following structure is used (from top to bottom):
>
> Patterned AZ4562 photomask
> Silicon substrate (this will be etched)
> Cool grease used to provide thermal contact between carrier wafer and
> substrate
> AZ4562 ~ 6 um thick spun onto Carrier Wafer
> 4 inch Carrier wafer
>
> They have found that after the etch the back of the silicon substrate
> (i.e. side which is not etched) has some carbon looking deposits which
> cannot be removed in O2 plasma or solvent. Does anyone have any idea
> where this carbon is coming from?
>
> I myself do a lot of ICP etching and have not seen this before so am at
> a loss to explain it.

--
Alexandre BOE
Post-doctoral researcher

UCL - EMIC
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