Gate dielectric thin film transistor for SiC-based field effect transistor and preparation method of gate dielectric thin film transistor

Abstract

The invention relates to a gate dielectric thin film transistor for a SiC-based field effect transistor and a preparation method of the gate dielectric thin film transistor. The preparation method comprises the following steps: providing a cleaned SiC substrate; a CaF2 thin film is deposited on the cleaned SiC substrate, and a CaF2 / SiC substrate is formed; evaporating a metal film on one side of the silicon carbide on the CaF2 / SiC substrate to serve as a gate electrode; the two-dimensional material is transferred to the CaF2 / SiC substrate; evaporating metal on the two-dimensional material to respectively obtain a source electrode and a drain electrode; and annealing by using inert gas to complete the preparation of the transistor. The transistor structurally comprises a gate electrode / SiC / CaF2 / two-dimensional material / source and drain electrodes from bottom to top. The gate dielectric film CaF2 prepared by the invention has the advantages of high air stability, no surface dangling bond, high dielectric constant, large forbidden bandwidth, low interface state density and the like.

Description

technical field [0001] The invention belongs to the field of gate dielectric layer growth and device application, and in particular relates to a gate dielectric thin film transistor used in a SiC-based field effect transistor and a preparation method thereof. Background technique [0002] As a popular semiconductor material for power devices, silicon carbide is one of the third-generation wide-bandgap semiconductors with a band gap between 2.3-3.3eV. It not only has a large electron saturation drift speed, high breakdown field strength, and radiation resistance It has the advantages of high chemical stability, high thermal conductivity, excellent physical and chemical stability, strong radiation resistance and mechanical strength. Based on these advantages, silicon carbide can be used to fabricate high-frequency, high-power devices for use in extreme environments. However, domestic and foreign silicon carbide-based MOSFETs, IGBTs, and SBD devices have encountered great chal...

AI Technical Summary

Problems solved by technology

However, silicon carbide-based MOSFETs, IGBTs, and SBD devices at home and abroad have encountered great challenges in terms of gate dielectric layer reliability and electron mobility, because the dielectric constant of SiC (9.7) is almost the same The dielectric constant (3.9) of the silicon dioxide layer formed at the bottom is three times that of silicon dioxide, and the internal electric field concentration effect of silicon dioxide is very obvious. Therefore, the operation of the transistor is very susceptible to the danger of the breakdown of the silicon dioxide dielectric, and it is difficult to play the role of silicon carbide. superiority

Importantly, the accumulation of element C in the process of thermally oxidizing SiC substrates to form SiO2 leads to a high defect density at the SiO2 / SiC interface, which enhances the scattering effect and greatly reduces the The mobility of

In addition, the technical threshold of silicon carbide homoepitaxial semi-insulating silicon carbide layer is high, the growth process is complex, the growth rate is slow, and the repeatability is low, making its cost high

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