Thickness measuring structure and measuring method for aluminum-gallium-nitrogen barrier layer

Abstract

The invention discloses an aluminum gallium nitride barrier layer thickness measurement structure and a measurement method. The measurement structure comprises a substrate; the heterojunction is located on the substrate and comprises a gallium nitride channel layer and an aluminum-gallium-nitrogen barrier layer, and two-dimensional electron gas is formed at the interface of the gallium nitride channel layer and the aluminum-gallium-nitrogen barrier layer; the first metal layer is located on the heterojunction, and the first metal layer is electrically connected with the two-dimensional electron gas; the passivation layer is located on the first metal layer and the heterojunction; and the second metal layer comprises a first metal pole plate and a second metal pole plate, wherein the first metal pole plate is completely or partially positioned in an area above the first metal layer, and the second metal pole plate is completely or partially positioned in an area above the two-dimensional electron gas. According to the measurement structure, the first parallel plate capacitor not containing the aluminum gallium nitrogen barrier layer and the second parallel plate capacitor containing the aluminum gallium nitrogen barrier layer can be formed, and the thickness of the aluminum gallium nitrogen barrier layer can be finally obtained based on a voltage-capacitance characteristic test and a parallel plate capacitor capacitance formula.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and in particular relates to an aluminum gallium nitrogen barrier layer thickness measurement structure and a measurement method. Background technique [0002] A high concentration of two-dimensional electron gas (Two-dimensional electron gas, 2DEG) will be formed at the interface of AlGaN / GaN heterojunction due to material polarization, and it has high carrier saturation mobility It can be said that the AlGaN / GaN heterojunction structure is the cornerstone of the GaN-based high electron mobility transistor (HMET). [0003] In epitaxial growth, the concentration of two-dimensional electron gas directly depends on the thickness of the AlGaN barrier layer and the content of Al composition, which will ultimately affect the current characteristics of the device. The thickness of the AlGaN barrier layer or the Al component content can be measured by some means, such as: scanning electron micro...

AI Technical Summary

Problems solved by technology

The capacitance value C in the above formula is obtained from actual measurement, and the vacuum dielectric constant ε 0 =8.854187817E-12F / m, the plate area S is the process design value, the dielectric constant ε of the AlGaN barrier layer can be obtained according to the empirical formula ε=9.5-0.5x, x is the proportion of the Al component in the AlGaN barrier layer, Therefore, the premise of using this method to measure the thickness of the AlGaN barrier layer is to know the proportion of Al composition in AlGaN. However, the actual situation is that when the thickness of the AlGaN barrier layer is not known, the proportion of Al composition is often unknown.

In addition, if the quality of the AlGaN barrier layer is low and there is a large leakage, or the Schottky contact is poor, the error of the result calculated by the above method will also be large

Images