High-threshold voltage gallium nitride enhanced transistor structure and preparation method thereof

Abstract

The invention provides a high-threshold voltage gallium nitride enhanced transistor structure and a preparation method thereof and relates to semiconductor technology. The high-threshold voltage gallium nitride enhanced transistor structure comprises a substrate, a GaN layer, an AlGaN layer and an insulating gate dielectric layer from bottom to top and is characterized in that the insulating gate dielectric layer comprises an insulating tunnel layer, a fixed charge layer and an insulating cap layer, wherein the fixed charge layer is arranged above the insulating tunnel layer or is embedded at the upper part of the insulating tunnel layer; the insulating cap layer is arranged above the fixed charge layer; and gate metal is arranged above the insulating cap layer. The high-threshold voltage gallium nitride enhanced transistor structure has the beneficial effects that compared with other technology for manufacturing an enhanced GaN field effect transistor, the controllability of the preparation process is good, and the performance repeatability of researched and developed devices is good; and a researched and developed GaN MlSHEMT device has the advantages of good performance, large threshold voltage, large biggest source leakage saturation current density, small gate current leakage and wide operating voltage range, and the research and development demands of a GaN integrated circuit can be fully satisfied.

Description

technical field [0001] The present invention relates to semiconductor technology. Background technique [0002] Compared with high electron mobility transistors (HEMTs) based on AlGaAs / GaAs (AlGaAs / GaAs) heterojunctions, HEMT devices based on AlGaN / GaN (AlGaN / GaN) heterojunctions have the following advantages: [0003] (1) The two-dimensional electron gas (2DEG) concentration at the AlGaN / GaN heterojunction interface is relatively high (up to 1013cm-2), which is nearly an order of magnitude higher than the 2DEG concentration at the AlGaAs / GaAs heterojunction interface. Therefore, based on AlGaN / GaN heterojunction HEMT will have higher output power density. As a mass-produced product, the power density of HEMT devices based on AlGaN / GaN heterojunction has reached more than 10W / mm, which is nearly 20 times higher than that of GaAs-based HEMT devices. [0004] (2) Since GaN is a wide bandgap semiconductor, its operating temperature is high and can work normally above 500°C, w...

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Problems solved by technology

[0010] The biggest disadvantage of this method is that it cannot achieve compatibility with depletion-mode GaN HEMT devices, that is to say, it is impossible to manufacture both enhancement-mode GaN HEMT devices and depletion-mode GaN HEMT devices on the same piece of material. Therefore, This method cannot meet the development needs of GaN digital logic circuits

[0012] Although this method is effective, its biggest problem is that it is difficult to accurately control the thickness of the AlGaN barrier layer in the gate region due to the difficulty in monitoring the etch rate. Therefore, the performance consistency and repeatability of the fabricated enhancement-mode GaN HEMT devices It is difficult to guarantee the reliability, which is also unacceptable for the development of GaN digital logic circuits

[0014] Although this method avoids the shortcomings of the above two methods, its biggest problem is that the F ion implantation of the AlGaN barrier layer in the gate region will destroy the characteristics of the AlGaN / GaN heterojunction interface and degrade the performance of the GaN enhanced HEMT device. , so that the performance of the developed GaN integrated circuit is poor

Moreover, in order to further increase the threshold voltage, the electrical performance of the device will be more severely degraded.

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