Novel optical probing and micromachining techniques for silicon debug of flip chip packaged microprocessors

Methods and techniques for micromachining and probing C4 packaged microproc essors from the silicon backside are described. The micromachining techniqu e is based on using a combination of Laser Chemical Etching and Focused Ion Beam milling to open precision probe holes and perform circuit editing fro m the backside. A method to optically probe flip chip packaged CMOS micropr ocessors is also described. The optical probing technique utilizes an infra red laser to probe diffusions directly through the silicon backside without the need to mill probe holes.