currently I use H3PO4 at 150 degree C to etch nitride layer. The nitride layer
can be etched at etch rate of 3-5 nm/min and standard AZ photoresist can be used
as mask. The problem is that the resist pattern can not protect the nitride
lying underneath the photoresist hence reduce the resolution. does anyone  know
how to improve this etching method ?

thanks

Dr. Jumril Yunas
Institute of Microengineering and Nanoelectronics (IMEN)
Universiti Kebangsaan Malaysia
43600 Bangi, Selangor - Malaysia
http://slim.ukm.my/tfolio/jumrilyunas.aspx   or
http://www.vlsi.eng.ukm.my/imen