Nitriding method of substrate and preparation method of gallium nitride buffer layer

Abstract

The substrate nitriding method and the gallium nitride buffer layer preparation method provided by the present invention are used to use inductively coupled plasma before the epitaxial growth of the gallium nitride buffer layer and after the pattern etching of the substrate is completed The processing equipment performs nitriding treatment on the surface of the substrate, including the following steps: feeding nitriding gas into the reaction chamber, and turning on the power supply of the upper electrode and the lower electrode, so as to form a nitride layer on the surface of the substrate. The nitriding method of the substrate provided by the invention can expand the nitriding window to form a sufficient and uniform nitrided layer on the surface of the substrate, thereby reducing buffer layer defects.

Description

technical field [0001] The invention relates to the technical field of microelectronics, in particular to a method for nitriding a substrate and a method for preparing a gallium nitride buffer layer. Background technique [0002] Sapphire (A1 2 o 3 ) has become a commonly used substrate material for GaN epitaxy technology because of its mature preparation process, heat resistance, easy surface treatment, and good stability at high temperatures. However, since Al 2 o 3 There is a large lattice constant mismatch with GaN, resulting in high dislocation density in the GaN epitaxial film, so in A1 2 o 3 There will be stress in the epitaxially grown GaN film on the substrate, which will cause more dislocations and defects, and seriously affect the crystal quality of the GaN film. [0003] For this reason, the usual method for preparing GaN thin films is to etch the sapphire substrate using ICP (Inductively Coupled Plasma) etching technology, and after removing the mask, use ...

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Problems solved by technology

[0009] Although the above preparation method can be used to obtain a relatively smooth GaN buffer layer, however, due to the 2 o 3 The substrate has good stability, and it is difficult to break the Al-O bond when nitriding is carried out at low temperature, which leads to uneven nitriding of the substrate surface and increases buffer layer defects

However, nitriding under high temperature conditions will lead to poor growth direction of the subsequent buffer layer, which cannot effectively release stress and reduce defects.

In addition, during the epitaxial process using MOCVD equipment, a large flow of carrier gas needs to be introduced into the reaction chamber, resulting in high chamber pressure, which will increase the number of collisions of molecules and reduce the free path of molecules, thereby Inhomogeneous nitriding results in deterioration of the optical and electrical properties of the epitaxial layer

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