Gigahertz logic gates based on InP-MISFET´s with minimal drain current drift

Three-input AND/NOR logic gates based on 3-µm overlapping gate InP-MISFET technology were fabricated and clocked at 1 GHz. The logic gates showed a propagation delay of ∼500-700 pS/gate for a channel length of 1.5 µm. Such high-speed performance was obtainable as a result of a novel process that was used in the fabrication of the MISFET´s. The process included the saturation of InP surface with phosphorus vapor and growth of a P2OxN1-xinterfacial layer followed by the deposition of an SiO2gate insulator. MISFET´s that were utilized in the logic gates showed a channel mobility of ∼3700 cm²/V.s and less than 3-percent drain current drift.