Michael,
Try one of the following:
(1) Ultrasonic machining (Bullen Ultrasonics)
(2) Diamond bit drilling (Mindrum Precision)

-Shivalik

----- Original Message -----
From: "Alderete, Michael"
Subject: [mems-talk] Mechanically machining thick [~4 mm] Silicon.

> Does anyone have experience with the mechanical machining of thick
> [approximately 4 mm thick] Silicon?
>