[labnetwork] Oxidation of Si wafers with DRIE passivation polymer

[Aaron Hryciw]

Dear colleagues,

Our facility recently installed a Tystar wet/dry oxidation tube, which has
so far only been used to oxidise virgin Si wafers.  Recently, one of our
users has requested to do a 400–1000 nm wet oxidation at 1100 °C on DRIE
(Bosch) etched Si wafers which still have DRIE passivation polymer on them,
for the dual purpose of removing the polymer and growing an oxide.

Given the tool's excellent performance so far, I am concerned with the
possibility of contaminating the (atmospheric) tube as the polymer is
burned off, adversely affecting subsequent processes.  My priority is to
protect the integrity of the tool, but I also do not want to be needlessly
restrictive if the presence of the polymer does not in fact pose any
problem.  We are a multi-user facility, with academic and industrial users
who primarily do MEMS and microfluidics work (i.e., no CMOS processing).

My initial thought would be to have this user remove the polymer first
using a dry etch (O₂ plasma), only oxidising the wafers once it has been
verified that the polymer is no longer present.

Any advice on this matter would be greatly appreciated.  Many thanks.

Cheers,

  – Aaron Hryciw




Aaron Hryciw, PhD, PEng

Fabrication Group Manager

University of Alberta - nanoFAB

W1-060 ECERF Building

9107 - 116 Street

Edmonton, Alberta

Canada T6G 2V4 Ph: 780-940-7938
www.nanofab.ualberta.ca
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