[labnetwork] Oxidation of Si wafers with DRIE passivation polymer

[Noah Clay]

Aaron,

We have a rather high power density oxygen barrel asher that removes Bosch polymer.  If you cross-section a test device, there’s an observable difference in SEM sidewall charging pre- and post barrel ashing.  You may also note the change in polymer mushrooming at the tops of features.  Definitely, use low keV SEM imaging.  

It’s been our experience that oxide will not burn off during furnace oxidation; rather, O2 will diffuse through the remaining carbonized layer.

Wet process alternative: EKC 265 from DuPont.  http://www.dupont.com/content/dam/dupont/products-and-services/electronic-and-electrical-materials/documents/ekc/EKC265.pdf

Best of Luck,
Noah

Noah Clay
Director, Quattrone Nanofabrication Facility
School of Engineering & Applied Science
University of Pennsylvania
Philadelphia, PA

(215) 898-9308
nclay at upenn.edu <mailto:nclay at upenn.edu>
LinkedIn Profile <https://www.linkedin.com/in/noah-clay-5073b3?trk=hp-identity-name>
> On Aug 3, 2016, at 2:34 PM, Aaron Hryciw <ahryciw at ualberta.ca> wrote:
> 
> 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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