ANALYSIS OF THERMAL EFFECT ON THE INTERFACIAL OXIDE BETWEEN POLYSILICON AND SILICON FOR POLYSILICON BIPOLAR-TRANSISTORS BY CAPACITANCE AND CONTACT RESISTANCE MEASUREMENTS

Thermal effect on the interfacial oxide between polysilicon and silico n doped with arsenic was analyzed by capacitance and contact resistanc e-measurements. The annealing temperature was varied from 850 degrees C to 1000 degrees C and, with the increase of annealing temperature, t he oxide breakup was enhanced and the contact resistance decreased. It is shown for the first time that the capacitance also decreased with the increase oi annealing temperature. This suggests that the interfac ial area of the oxide layer decreases and the oxide layer thickness in creases due to the oxide breakup. Capacitance characteristics are also compared with bipolar transistor characteristics.