Mr Yan,

    Sorry. The dimension calculation in last message is wrong.

    From my understanding, undercut refers to the difference betweeen oxide and
silicon. That is, if the silicon hole size is 10um, then the oxide hole size
will be 10+1.8*2=13.6 um.

                                          Matthew King



> Hi everyone,
>
> For the inertial sensors, we usually need to perforate the
> suspended
> structure to release the structure with wet etching
> process.
> -But how to know if the holes are big or dense enough to
> release the structure
> completely?
>
> For example, in the SOIMUMPs process, the oxide layer is 1
> microm, the
> structure layer is about 25 micron, undercut is 1.8 micron
> per side by  HF
> vapor etching,
> -Does this mean that  the distance between edges of  two
> adjacent etched
> holes must be less the 1.8*2 micron if i need  to release
> the structure
> completely?