Evelyn

E-beam and evap is the same - just using different methods to heat the
material. In evaporation, the material goes in straight lines from the
source (few square cm) to all directions (in that vacuum the mean free path
of the molecules is few meters!). Unless you rotate the substrate around as
is usually done, you get film thickness which is dependent on the cosine of
angle between the substrate and the line of flight. If the angle is zero
i.e. the substrate is perpendicular to the line you get maximum thickness.
In Sputtering, the vacuum is not as good so the mean few path of the
molecules is shorter and also the source and the target are large so the
coverage is theoretically conformal.

In addition, there are some second order effects such as surface diffusion
etc. that can affect sharp step coverage.

shay

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Evelyn B
Sent: Saturday, May 02, 2009 3:43 PM
To: General MEMS discussion; Evelyn Benabe
Subject: [mems-talk] Lift-off Profile

To all,

I am trying to figure out what e-beam, sputtering, and thermal evaporation
metal deposition profiles look like.  I read in Coventorware that the
e-beam's profile is supposed to be conformal but I have heard otherwise from
other sources.  Does anyone have cross sectional views/pictures of a
Substrate/Negative Resist/Metal deposited using either of these methods?  I
am mostly interested in seeing what the wall coverage looks like.  It would
be greatly appreciated.