Gate current injection in MOSFET's with a split-gate (virtual drain) structure

Gate current injection into the gate oxide of MOSFETs with a split-gate (virtual drain) structure is examined. The split-gate structure is commonly encountered in flash EEPROM and CCDs. An important parameter characterizing the gate current injection is the ratio phi /sub b// phi /sub i/ (where phi /sub b/ is the effective energy barrier for electron injection into gate oxide, and phi /sub i/, is the impact ionization energy). Measurements of phi /sub b// phi /sub i/ at relatively constant vertical and lateral electric fields are reported. Through the use of a novel triple-gate MOSFET, the drain current as well as the lateral and vertical electric field at the point of injection were independently controlled during the measurements. The measured phi /sub b// phi /sub i/ showed a dependence on gate and drain biases not reported previously.<
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