Integrated circuit with HV input stage - has switching MOSFET on substrate with insulated gate electrode having gate oxide layer of equal thickness to field oxide layer

摘要

The gate electrode (38) of the switching MOSFET (14) is insulated against the substrate (10) by a thin gate oxide film (36). Under the gate electrode the substrate has implanted ions for adjusting the transistor threshold voltage. The electric leads for the gate, drain, and source electrodes are insulated against the substrate by a field oxide layer (40) of greater thickness. The thickness of the gate oxide film (42) of the MOS input transistor is the same as that of the field oxide layer. The MOS input transistor is formed without ion implantation underneath its thick gate oxide layer. USE/ADVANTAGE - For HV breakdown-resistant input stage, without need for change of the process parameters and mfg. course.