[labnetwork] Oxidation of Si wafers with DRIE passivation polymer

[Vito Logiudice]

Hi Aaron,

Great comments so far on this topic.

I will add a suggestion that you might want to consider. I assume you typically have two, 24-wafer quartz boats loaded in this furnace at any given time. If you do decide to allow clean, previously processed wafers in this tube in the future together with your usual virgin wafers, perhaps you might want to dedicate the boat closest to the source (ie., the one furthest away from the loading end) to your virgin Si wafers and the tail end of your second boat to the previously processed wafers. The thinking here is that contaminants, if any, would likely tend to diffuse towards the load end of the furnace quartzware over time rather than the source end, thus keeping at least a good portion of the tube as pristine as possible. As an aside, I would not even consider this approach for a CMOS oxidation tube.

Best,
Vito
--
Vito Logiudice  P.Eng.
Director of Operations, Quantum NanoFab
University of Waterloo
Lazaridis QNC 1207
200 University Avenue West
Waterloo, ON           Canada N2L 3G1
Tel.: (519) 888-4567  ext. 38703
Email: vito.logiudice at uwaterloo.ca<mailto:vito.logiudice at uwaterloo.ca>
Website: https://fab.qnc.uwaterloo.ca


From: <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> on behalf of Aaron Hryciw <ahryciw at ualberta.ca<mailto:ahryciw at ualberta.ca>>
Date: Wednesday, August 3, 2016 at 2:34 PM
To: "labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>" <labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>>
Subject: [labnetwork] Oxidation of Si wafers with DRIE passivation polymer

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<http://www.nanofab.ualberta.ca/>

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