How about using the differential etch rate of doped silicon.  Heavily
phosphorus doped silicon etches faster than non doped.  With a varying
level of dopant, this occurs naturally you can have a varying etch rate
of Silicon.


Bill Moffat, CEO
Yield Engineering Systems, Inc.
2185 Oakland Rd., San Jose, CA  95131
(408) 954-8353

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: Wednesday, April 19, 2006 6:45 PM
To: [email protected]
Subject: [mems-talk] Silicon Ramp Needed

OK Mems people, work with me. This is a real question.  How can I make a
silicon ramp 5um tall on one end and 1um on the other, 250um long, 5um
wide?  I'm starting with a 5um layer of Si on a substrate.  The real
question is how to etch/make a smooth, ramp, type structure.  I feel a
few lith steps of 1um 4 times to build "stairs" and then figure a way to
smooth the 1um steps.  Anyone????