Etching Away HSQ

Holzwarth, Charles W charles.w.holzwarth at
Mon Oct 10 08:41:42 PDT 2011


HSQ is basically a very low quality SiOx after ebeam pattering so HF works great to remove it.  In my previous work in Si photonics this was complicated by the fact that the BOX layer of the SOI wafer was exposed when the HSQ was to be removed.  I found that an SC-1 clean followed by a 4 min dip in 0.125% solution of HF was enough to remove my HSQ etch mask without significantly etching the BOX.

How easy it is to remove the HSQ can vary significantly depending on the e-beam dose used and other processes the HSQ will see.  For example annealing the HSQ after development will make it significantly harder to remove.  My HSQ for the process above was exposed with a dose of 1500uC/cm^2 developed by 25% TMAH and used as an etch mask during RIE using HBr as the etch gas before I removed it.

Best regards,

From: robertatx at [mailto:robertatx at] On Behalf Of Robert Chen
Sent: Sunday, October 09, 2011 6:43 PM
To: labmembers at
Subject: Etching Away HSQ

Hi Labmembers,

Does anyone have experience etching away HSQ masks patterned using e-beam? Looking for recipes, etch rates, and general considerations.


Robert Chen
Electrical Engineering Ph.D. Candidate
Harris MBE Group, Stanford University
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the labmembers mailing list