Structure for improving quality of epitaxial layer of gallium nitride device and preparation method thereof

Abstract

The invention discloses a structure for improving the quality of an epitaxial layer of a gallium nitride device and a preparation method thereof, and the problem of poor quality of an epitaxial layerof the existing gallium nitride device is solved. The structure comprises a substrate, an i-GaN layer and a GaN cap layer, the substrate is located at the lowest layer, the GaN cap layer is located atthe topmost layer, an AlN buffer layer is disposed on the upper portion of the substrate, a AlGaN barrier layer is disposed under the GaN cap layer. the i-GaN layer is disposed under the AlGaN barrier layer, a c-GaN layer is arranged at the lower portion of the i-GaN layer, a graded multilayer buffer layer is arranged between the c-GaN layer and the AlN buffer layer, and an AlN spacer layer is disposed between the AlGaN barrier layer and the i-GaN layer. The graded multilayer buffer layer is inserted between the GaN and the AlN by adopting the substrate, the graded multilayer buffer layer isformed by adopting the multi-layer AlGaN structure grown in order to greatly solve the warpage caused by lattice stress, and the internal stress accumulation due to thermal expansion mismatch and forma more stable epitaxial structure.

Description

technical field [0001] The invention relates to the field of gallium nitride devices, in particular to a structure for improving the quality of epitaxial layers of gallium nitride devices. Background technique [0002] The technology of GaN epitaxy on the Si substrate in the internal structure of GaN devices, due to the mismatch of the lattice constant and the thermal expansion coefficient of GaN and the Si substrate, in order to avoid the remelting phenomenon of Ga atoms on the Si substrate, the Si substrate However, the lattice constant mismatch and thermal expansion coefficient mismatch between AlN and Si substrate, and the lattice constant mismatch and thermal expansion coefficient mismatch between GaN and AlN will cause GaN Poor quality of epitaxial layer and warpage of epitaxial wafer. Poor quality of epitaxial layer and high defect density will lead to decreased electron mobility, leakage and poor reliability of electronic devices. Warpage of epitaxial wafer will caus...

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Problems solved by technology

[0002] The technology of GaN epitaxy on the Si substrate in the internal structure of GaN devices, due to the mismatch of the lattice constant and the thermal expansion coefficient of GaN and the Si substrate, in order to avoid the remelting phenomenon of Ga atoms on the Si substrate, the Si substrate However, the lattice constant mismatch and thermal expansion coefficient mismatch between AlN and Si substrate, and the lattice constant mismatch and thermal expansion coefficient mismatch between GaN and AlN will cause GaN Poor quality of epitaxial layer and warpage of epitaxial wafer. Poor quality of epitaxial layer and high defect density will lead to decreased electron mobility, leakage and poor reliability of electronic devices. Warpage of epitaxial wafer will cause problems in the manufacturing process. Problems such as fragile chips and poor exposure yield of yellow light process

[0003] The current solution is to insert an AlGaN buffer layer with an appropriate Al content between GaN and AlN, because its lattice constant and thermal expansion coefficient are both between GaN and AlN, so as to obtain a buffer effect and slow down the effect caused by the lattice constant and thermal expansion coefficient. Disadvantages caused by excessive differences, but with the development of technology, the quality requirements of GaN channels are increasing and the development of large-scale epitaxial wafers, the existing technical solutions no longer meet the needs, and people are also conducting related research

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