Optical Integrated Circuit Probing Method and Apparatus
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
By scanning a focussed broadband infrared light beam through the backside of a thinned integrated circuit (IC) while simultaneously exercising the circuit electronically, electrical state of discrete devices in the illuminated area are identified by a change in device power characteristics caused by induced free carriers. Synchronously scanning and electronically exercising two ICs speeds and enhances detection of differences between "good" and "bad" devices. Referring to the figure, a light source 2 having a level of infrared in its spectral output is collimated to strike beam splitter 4. Half of the input light energy goes through transfer lense system 6 and is reflected by mirror 8 into microscope A. The other half of the input light goes through adjustable neutral density filter wheel 10 and into microscope B.