ELECTRO-OPTIC PROBES FOR ON-WAFER TESTING OF GAAS MMICS

IN THE PROPOSED RESEARCH, LIGHTWAVE ELECTRONICS WILL INVESTIGATE MAKING SEPARATE OFF-SUBSTRATE MICROPROBES FOR GALLIUM ARSENIDE (GAAS) MONOLITHIC MICROWAVE INTEGRATED CIRCUITS (MMICS) BASED UPON THE ELECTRO-OPTIC SAMPLING TECHNIQUE. THESE PROBES WILL BE OF A SUFFICIENTLY SMALL SIZE SO THAT WHEN THEY ARE PLACED NEXT TO OR IN CONTACT WITH THE CIRCUIT OR DEVICE TO BE TESTED THEY WOULD NOT LOAD OR PERTURB IT. THIS TECHNIQUE MEASURES BOTH THE MAGNITUDE AND PHASE OF VOLTAGE WAVEFORMS AT PRECISE POINTS WITHIN THE MMICS, BUT IT DOES NOT REQUIRE POLISHED SURFACES OR A CLEAR OPTICAL PATH INTO THE DEVICE SUBSTRATE AT THE MEASUREMENT POINT AS IS THE CASE WHEN PROBING DIRECTLY IN THE SEMICONDUCTOR SUBSTRATE.