The present invention describes a processes that builds an acoustic cavity, a
chamber, and vent openings for acoustically connecting the chamber with the acoustic
cavity. The dry etch processes may include reactive ion etches, which include traditional
parallel plate RIE dry etch processes, advanced deep and inductively coupled plasma
RIE processes. Three embodiments for connecting the chamber to the cavity from
the top side of the substrate, e.g. by using pilot openings formed using at least
a portion of the mesh as an etch mask, by forming the vent openings using at least
a portion of the mesh as an etch mask, or by having the chamber intersect the vent
openings as the chamber is being formed, illustrate how the disclosed process may
be modified. By forming the cavity on the back side of the substrate, the depth
of the vent holes is decreased. Additionally, using at least a portion of the micro-machined
mesh as an etch mask for the vent holes makes the process self-aligning.