Multi-threshold field MOSFET and multi-threshold field MOSFET unit

Abstract

A multi-threshold field MOSFET and a multi-threshold field MOSFET unit belong to the technical field of metal oxide semiconductor field-effect transistors. The multi-threshold field MOSFET comprises a gate electrode, a gate dielectric layer, a channel region, a source electrode, a drain electrode and a semiconductor substrate, the gate dielectric layer is a shallow trench isolation dielectric layer, the gate electrode is composed on the gate dielectric layer, the gate dielectric layer comprises a first part of gate dielectric layer covered by the gate electrode and a second part of gate dielectric layer uncovered by the gate electrode, the area ratio of the second part of gate dielectric layer to the first part of gate dielectric layer is adjusted by the composition of the gate electrode so as to change unit-area capacitance Cox, thus determining threshold voltage of the multi-threshold field MOSFET. The multi-threshold field MOSFET is characterized by easily changing the threshold voltage. The multi-threshold filed MOSFET unit consisting of a plurality of the multi-threshold field MOSFETs is characterized by different threshold voltages, and has the advantages of simple process and low cost.

Description

technical field [0001] The invention belongs to the technical field of Metal-Oxide-Semiconductor-Field-Effect-Transistor (MOSFET), in particular to a multi-threshold field MOSFET (Multi-Vth Field MOSFET) and a multi-threshold field MOSFET group. In particular, it relates to a multi-threshold field MOSFET whose threshold voltage is determined by patterning and adjusting the pattern of the gate electrode on the STI (Shallow Trench Insulator, shallow trench isolation layer) layer. Background technique [0002] MOSFET is one of the basic components in integrated circuits, and its basic physical principles have been well known by industry technicians. The formula for calculating the threshold voltage (Vth) of the MOSFET is listed in the following formula (1). [0003] [0004] In formula (1), Vth is the threshold voltage, ψ FB is the flat-band voltage, is the Fermi potential difference, N A is the doping concentration of the channel substrate region (this formula is the c...

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Problems solved by technology

Those skilled in the art know that in the above-mentioned doping step, the process is relatively complicated, and an additional mask may be required, and N A It is difficult to control precisely, which makes Vth difficult to control precisely

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