Growing a thick oxide (1000A or more) will smooth out rough features on
silicon after stripping in HF. A polishing etch might also do the same job,
but you're going to lose some silicon either way.

A gray-scale photomask would allow you to develop photoresist in a gradient
like the ramp.

You could also deposit your silicon at an angle onto your substrate then
etch away what you don't need.

Last suggestion would be to ion mill the structure, but I don't have any
experience with that personally. I think Sandia National Labs has a tool,
but I don't know of anyone else.

Mike

x1927
[email protected]

-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Wednesday, April 19, 2006 9:45 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????

Brent