Patent ID: 8133760

Claim:
A system for accessing circuitry on a silicon device, comprising: a flip chip circuit device comprising active circuitry and full-thickness bulk silicon; a moveable surface for supporting and locating the circuit device in a plane; an infrared (IR) imaging device located at a defined perpendicular distance from a surface of the bulk silicon, the surface of the bulk silicon parallel to the plane; a milling chamber configured to direct an etchant and a focused ion beam to the surface of the bulk silicon, the etchant and the focused ion beam capable of creating a milled cavity in the bulk silicon; an IR reflective material located at a base of the cavity; and wherein the circuit device is located within a field of view of the IR imaging device such that the IR reflective material is brought into focus by moving the IR imaging device an adjustable distance perpendicular to the surface of the bulk silicon, and where the adjustable perpendicular distance is indicative of a depth of the cavity.