Gate oxide structure and preparation method

Abstract

The invention relates to a gate oxide structure and a preparation method in the technical field of semiconductors, the gate oxide structure comprises a SiC substrate layer, an oxide layer, an Al2O3 layer and a high dielectric material layer, the oxide layer is arranged on the SiC substrate layer of the gate oxide structure and the preparation method, the Al2O3 layer is arranged on the oxide layer of the gate oxide structure and the preparation method, and the high dielectric material layer is arranged on the high dielectric material layer. According to the gate-oxide structure and the preparation method, the high-dielectric material layer is arranged on one side, far away from the oxide layer, of the Al2O3 layer, so that the gate-oxide structure has the advantages of high channel mobility and small gate energy loss, and breaks through the bottleneck that the gate of the traditional gate-oxide structure is easy to leak current.

Description

technical field [0001] The present application relates to the field of semiconductor technology, in particular to a gate oxide structure and a preparation method. Background technique [0002] SiC-based power devices benefit from the superior physical properties of SiC materials such as wide bandgap, high breakdown field strength, and high thermal conductivity. The field has great prospects. In the preparation process of SiC power devices, especially Metal-Oxide-Semiconductor Field-Effect Transistors (Metal-Oxide-Semiconductor Field-Effect Transistors, MOSFETs), lower quality gate interface oxides have greatly limited performance of power devices. [0003] The gate oxide used in the current stage is often SiO 2 materials, which are usually grown by direct thermal oxidation of SiC, but for thermal oxygen grown SiO 2 layer, more interface defects will inevitably appear at the interface, resulting in a sharp drop in channel mobility, which is far from the theoretical electro...

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Problems solved by technology

[0002] SiC-based power devices benefit from the superior physical properties of SiC materials such as wide bandgap, high breakdown field strength, and high thermal conductivity. The field has great prospects. In the preparation process of SiC power devices, especially Metal-Oxide-Semiconductor Field-Effect Transistors (Metal-Oxide-Semiconductor Field-Effect Transistors, MOSFETs), lower quality gate interface oxides have greatly limited Performance of power devices

[0003] The gate oxide used in the current stage is often SiO 2 materials, which are usually grown by direct thermal oxidation of SiC, but for thermal oxygen grown SiO 2 layer, more interface defects will inevitably appear at the interface, resulting in a sharp drop in channel mobility, which is far from the theoretical electron mobility of SiC. In addition, due to SiO 2 The dielectric constant is only 3.9, which will increase the electric field at the gate oxide material, which poses a big problem for its reliability

[0004] as SiO 2 material substitution to Al 2 o 3 , HfO 2 Gate oxide materials represented by high dielectric constant materials have been widely studied in recent years. However, compared with SiO 2 , the bandgap width is often narrow, so that under the action of the gate voltage, due to the matching of the high dielectric constant material and SiC, the gap between the conduction band and the valence band is small, so that electrons can easily cross the potential barrier, resulting in a larger Large tunneling current, resulting in large energy loss at the gate

[0005] On the other hand, the traditional gate oxide structure by SiO 2 Set Al on 2 o 3 layer, although it can further widen the carrier barrier at the gate oxide, thereby reducing the tunneling current, but due to Al 2 o 3 There are many crystal phases in the material, and in the process of heating and cooling, various crystal phase structures will transform each other, and it is easy to produce grain boundaries, so that under the action of the gate voltage, the Al 2 o 3 The material is prone to gate leakage current, and then it is easy to break down under high field strength, resulting in great difficulties in practical applications

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