Hi all,

Does anyone use RIE silicon etching for features under 200nm dimension?

I'm using evaporated Aluminum as mask and silicon substrate. The width of
desired features ranges from 100nm to 200nm. I've been trying SemiGroup RIE
(recipe: SF6 15sccm; O2 7.5sccm; 30mTorr; 100W) and Trion RIE (recipe: CF4
25sccm; ICP Power 300W; RIE Power 90W; 20mTorr). However, I always
experience terrible transfer from mask to substrate. For example, for a
200nm wide slot pattern with straight edges, after RIE, the edges become no
straight anymore. What even worse is certain parts of the substrate have
been successfully etched away, others are not. The depth of the etch may
range from 20nm to 80nm. If the slot width is less than 200nm, like 150nm,
the substrate barely got etched.

The lab manager told me the dimensions I'm trying to etch may be challenging
for this equipment. I'm just wondering if this problem is a recipe-related
issue or just because the regular RIE equipment is incapable in etching such
small features. Actually, I have couple AFM images that might be helpful to
better illustrate the problem. I'm happy to share it with you via email.

Any thoughts would be highly appreciated!

Thanks,
Li

--
Li. Zhang
---------
Graduate Research Assistant
Edward P. Fitts Department of Industrial and Systems Engineering
North Carolina State University
416, 111 Lampe Dr., Daniels Hall
Raleigh, NC 27695-7906
USA
TEL: (919) 413-5459
Email: lzhang13@ncsu.edu
Web:  http://www.ise.ncsu.edu
          http://www.nnf.ncsu.edu