High Speed Polycrystaline Silicon Photoconductors for on-Chip Pulsing and Gating

摘要

Photoconductor based time-domain measurement techniques for testing silicon integrated circuits are the focus of this research. The objective is to produce a very high speed sampling system which may be integrated using standard integrated circuit (IC) processing technology and provide for on-chip characterization at frequencies higher than current measurement systems allow. Integrated photoconductors constructed on silicon wafers of 6 to 70 ohm-cm resistivity from annealed polycrystaline silicon and damaged by ion-beam irradiation are reported. They are used in an optoelectronic sampling system to perform high frequency measurements of picosecond pulse propagation in IC microstrip interconnections. Optoelectronic correlation measurements of photoconductor pulses and photoconductor sampling gates are used to characterize both the photoconductors and the IC interconnections. A subpicosecond pulsed laser system is used to excite the photoconductors to generate and sample the high frequency pulses. Photoconductors processed as fast pulsers produced approx. 20 mV peak magnitude, 3 picosecond Full W idth at Half Magnitude (FWHM) pulses while photoconductors processed as large-signal step pulsers produced approx. 200 mV peak magnitude, 6 picosecond risetime pulses of fifty picosecond duration.