电场调制增强型AlGaN/GaN HEMT关键技术研究

In this project, the electric field modulation effect, which had been proposed by the applicant, is applied to the new GaN-based power semiconductor devices for the first time. The novel Enhancement-Mode AlGaN/GaN HEMT is proposed with the electric field modulation effect. There are three innovation researches including of the theory and experiment in this project. Firstly, the novel Enhancement-Mode AlGaN/GaN HEMT with the electric field modulation effect is proposed for the first time, and the physical essence will be analyzed. Secondly, the electric field distribution and breakdown model will be set up to resolve essentially the mechanism of the electric field optimization for AlGaN/GaN HEMT. Thirdly, the key process of the novel Enhancement-Mode AlGaN/GaN HEMT will be explored to fabricate AlGaN/GaN HEMT sample with the electric field modulation effect. The new theories and methods of the terminal technology for AlGaN/GaN HEMT will be obtained by this project. The sample of AlGaN/GaN HEMT will be realized with the breakdown voltage greater than 600V. The basic theory will be founded for the power semiconductors based on GaN material. The key technologies will be provided to break through the design of the new GaN-based power semiconductor devices.

本项目首次将申请者在功率半导体领域提出的电场调制应用于新型GaN基功率半导体器件设计，提出并实现具有电场调制增强型AlGaN/GaN HEMT器件。主要进行三项创新研究：(1) 设计并提出具有电场调制效应新型增强型AlGaN/GaN HEMT器件结构，分析电场调制效应的物理本质 (2) 建立电场调制新型增强型AlGaN/GaN HEMT器件的电场分布模型和耐压模型，从本质上解释新型AlGaN/GaN HEMT器件电场优化的方法和机理 (3) 探索电场调制新型增强型AlGaN/GaN HEMT器件的关键工艺，并制备具有电场调制增强型AlGaN/GaN HEMT器件。通过项目实施，获得GaN基功率器件终端设计的新理论和新方法；获得击穿电压大于600V的自主知识产权器件样品，为我国发展新型GaN基功率器件奠定理论基础，为突破新型GaN基功率器件的关键技术提供支撑。

在功率半导体技术中，AlGaN/GaN HEMTs功率半导体器件是一种备受关注的器件结构。当其应用于高压大功率领域时，击穿电压是一个重要的参数，优化击穿电压和比导通电阻的矛盾关系是实现低功耗系统的关键。本项目首次将申请者在功率半导体领域提出的电场调制应用于新型GaN基功率半导体器件设计，提出并实现了具有电场调制效应新型AlGaN/GaN HEMTs器件。首先提出了一种电场调制阶梯AlGaN/GaN HEMTs器件，这种结构是在栅漏漂移区之间靠近栅边缘处，刻蚀了AlGaN势垒层，AlGaN势垒层的厚度出现差异，形成了阶梯AlGaN势垒层。接着在完全耗尽和不完全耗尽两种情况下，根据Poisson方程，利用合适的边界条件，建立了电场调制阶梯AlGaN/GaN HEMTs器件在击穿时沟道电势电场分布的二维解析模型。通过与仿真结果之间的对比，讨论了参数的变化对阶梯AlGaN/GaN HEMTs器件击穿特性的影响，二者之间的一致性充分证明了该模型的有效性。最后，对电场调制阶梯AlGaN/GaN HEMTs器件进行了实验研究。在高质量样片的基础上，经过台面隔离、源漏电极欧姆接触、栅电极肖特基接触和阶梯AlGaN势垒层刻蚀的工艺流程，成功制备了样品。测试表明，传统AlGaN/GaN HEMTs器件的击穿电压为151 V，输出饱和电流为359 mA/mm。当刻蚀深度为10 nm、长度为7 μm时，刻蚀AlGaN势垒层AlGaN/GaN HEMTs器件的击穿电压为621 V，输出饱和电流为466 mA/mm。可以看出，击穿电压提高了311%，输出饱和电流增加了30%。.通过项目的实施，获得GaN基功率器件终端设计的新理论和新方法；获得击穿电压大于600V的自主知识产权器件样品，为我国发展新型GaN基功率器件奠定理论基础，为突破新型GaN基功率器件的关键技术提供支撑。