> To: labnetwork@mtl.mit.edu
> We are looking for noncontaminating alternatives for ceramic jacketed T/C's
> used in an 800 degree C. nitride process.....
> (clip)
> Scott Blondell
> Facilities Manager
> Microelectronic Engineering Dept.
> Rochester Institute of Technology
The UC Berkeley Microlab has operated silicon nitride furnaces for more than
20 years. Our present tube configurations have been in use for 14 years. Our
thermocouples are type R which are sheathed in quartz and enter the tube
through a rear tubulation for internal thermocouple control. We operate one
3-point controlled tube and one 5-point controlled tube.
Silicon nitride tubes are not routinely cleaned. Our tubes operate for more
than two years without breakage even though we deposit thick nitride films.
Our nitride tubes survive temperature cycling following a power failure
(our thick poly tubes, with equivalent depositions do not). Thermocouple
sheaths remain intact throughout operations. Reasons we do not routinely
clean out nitride tubes are:
1) We do not have particle problems throughout the lifetime of the tube
from stoiciometric or non-stoichiometric deposition. Films are adherent
and do not flake. Low-stress films are routinely tested for incoroporated
particles using KOH etch.
2) There is no convenient selective etch for silicon nitride vs. fused silica
to clean tubes.
Particles found in nitride films often result from post tube depostions of
process residues. The high vapor pressure of these deposits result in chemical
vapor deposition of particles onto clean wafers during loading. Control
of these post tube residues is the key to low particle counts in silicon
nitride films.
Bob Hamilton
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| University of California at Berkeley |
| Department of Electrical Engineering and Computer Sciences |
| Bob Hamilton bob@eecs.berkeley.edu |
| Senior Development Engineer fax: 510 642-2916 |
| Microlab Manager phone: 510 642-2716 |
| EECS/ERL Microfabrication Laboratory page: 510 442-4397 |
| 406 Cory Hall # 1770 preference: e-mail |
| Berkeley, CA 94720-1770 http://www-microlab.eecs.berkeley.edu |
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