That brings up a good point.  Chan, what type of DRIE system do you
have?  Is it an ICP-RIE system or of another type (for example,
parallel plate).

I also know it is possible to do DRIE without Ar as our system just
uses SF6, C4F8, and O2, so knowing your species might help people
give further suggestions.

Nik

At 1:04 PM -0400 9/12/06, Isaac Chan wrote:
>
>Some nice explanation of RIE process you have there. But sorry just want
>to clarify some points you made there. Actually reactive ion etching is
>not a technically correct term to describe this etching process because
>ions in capacitively coupled 13.56MHz rf plasma constitute typically less
>than 0.1% of total plasma species in the chamber. So etching should not be
>significantly caused by "reactive ions." If I remember correctly, the term
>was coined before researchers understood what was really going on in an
>RIE process, thus leaving such incorrect name. Ion bombardment "cleans"
>the surface of passivating species, like SxFy and CxFy, as well as
>amorphizing the silicon network to enhance chemisorption of reactive
>neutral species, such as F, onto the surface for chemical reactions.
>Surface silicon atoms seldomly left dangling for a long period of time.
>Thus without this physical ion bombardment, F adsoption rate on Si surface
>is very low, even though the raw Si + F reaction is very exothermic.
>
>Back to that question, increasing rf power and cycling frequency will help
>but more reactive species are also generated if rf power, not ICP, is the
>means to create and sustain the plasma. I read a paper, Journal of Vacuum
>Science and Technology B vo.17 no.6 pp.2768, detailing a bosch-type
>process using SF6/Ar and CF3/Ar gas mixtures. Ar provides the main source
>of ion bombardment. It is definitely worth a read.