hi,

Another good way is to etch by HF.
coat with PMMA / polymer/ scratch 1 mm diameter by scrubber and remove PMMA
and etch it in HF / KOH

Or put a kapton tape on the wafer by punching a 1 mm hole on the tape. and
etch it. It may take more time but it is also a very cheap method.
remember to tape backside also and shake it while etching.

Nabhiraj

On Mon, Dec 6, 2010 at 10:11 PM, Shay Kaplan  wrote:

> The cheapset way is to go to a dentist and ask for a diamond or Ti carbide
> drill. Attach the tip to a Dremel high speed tool. Then using some putty,
> create a bath of water around the place where you want to hole and drill
> using the machine weight only - not force. Make sure to hold the dremel
> vertically, the best is if you have a stand.
>
> shay