Gate-current injection and surface impact ionization in MOSFET's with a gate induced virtual drain

In this paper, gate current injection into the gate oxide of MOSFET's with a split-gate (virtual drain) structure is examined. The split-gate structure is commonly employed in flash EEPROM and CCD's. 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). We present new experimental data of the ratio phi /sub b// phi /sub i/ measured at relatively constant vertical and lateral electric fields. Using a novel triple-gate MOSFET, the vertical field, the lateral field, and the drain current of the MOSFET can be independently controlled using proper biases. The measured phi /sub b// phi /sub i/ ranged from 2.6 to 3.2 depending on gate and drain biases, and gate geometry.<
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