Reliability study of ONO gate film in high speed PTOx-TMOS based on electrical characteristics under high electric field

The purpose of this study is to clarify the more reliable design for ONO Gate insulator film for Trench Gate MOSFET. Partially Thick Oxide Trench Gate MOSFET (PTOx-TMOS) with ONO Gate film can reduce the Ron*Qgd Figure of Merit on easy process and simple structure. However this structure is required the appropriate design to prevent threshold voltage shift originated in charge storage effect. In this study, charge storage mechanism is analyzed experimentally and theoretically with the Fowler-Nordheim and Direct-Tunneling electric conduction behavior in high electric field.