Experimental results on three-phase Polysilicon CCD's with a TCE-SiO2/Si3N4gate insulator

A three-phase charge-coupled device (CCD) technology with three levels of polysilicon and trichloroethylene (TCE) oxide-silicon nitride gate, having a good processing yield and taking full advantage of the self-aligning property of silicon gate transistors, is presented. The use of a TCE gate oxide results in a storage time between 3-4 min, measured on the CCD itself. The presence of the silicon nitride requires a suitable combination of low-and high-temperature anneals in order to decrease the density of fast surface states. A reliability problem observed at high clock voltages is attributed to trapping of injected hot carriers in the gate insulator.