Roughening of resist-masked Si in buffered HF solutions

HF-based buffered oxide etch (BOE) solutions are commonly used in semiconductor
processing for etching SiO2 selectively to Si in the presence of photoresist masks. This paper reports on an anomalously severe roughening reaction that can occur at Si/resist interfaces when n-type Si is etched in 50:1 BOE solutions (1 wt% HF and 39.5 wt% NH4F in H2O) in the presence of certain organic resists. This effect is seen to a very much lesser extent in 9:1 BOE solutions (5 wt% HF and 36 wt% NH4F in H2O), and not seen at all in dilute HF solutions (100:1 and 10:1 with 0.5 wt% and 5 wt% HF). The species responsible for the roughening reaction is not identified, but it appears to be related to
a breakdown product of the resist. We show that the roughening can be eliminated with the use of a diamond-like-carbon interposer layer under the resist.

By: Katherine L. Saenger, Sharee J. McNab, Steven J. Koester

Published in: RC22843 in 2003


This Research Report is available. This report has been submitted for publication outside of IBM and will probably be copyrighted if accepted for publication. It has been issued as a Research Report for early dissemination of its contents. In view of the transfer of copyright to the outside publisher, its distribution outside of IBM prior to publication should be limited to peer communications and specific requests. After outside publication, requests should be filled only by reprints or legally obtained copies of the article (e.g., payment of royalties). I have read and understand this notice and am a member of the scientific community outside or inside of IBM seeking a single copy only.


Questions about this service can be mailed to .