基于FinFET结构的GaN基数字电路关键技术研究

Abstract：AlGaN/GaN heterostructures transistors are promising for power and switching applications. To date, the applications of the devices have been extended to digital circuit. The application of FinFET structure has a great progress in resolving short-channel-effect. The key research points of this project focuses on the formation mechanisms and realization methods of the enhancement-mode AlGaN/GaN HEMTs and GaN digital curcuit based on FinFET structure and thin barrier AlGaN. The main research contents include the growth of thin barrier AlGaN/GaN heterostructure adjusted by SiN stress; Designing optimal enhancement-mode AlGaN/GaN HEMTs device structure by FinFET application; Improvement device high-frequency characteristic by nano-size gate-length and selective etching on ohmic electrode; Process and reliability evaluation of E-D mode GaN digital circuit. The formation mechanisms and key technologies of the enhancement-mode AlGaN/GaN HEMTs based on FinFET structure will be investigated by means of I-V and C-V in variable temperature and frequency. Meanwhile, the relationship between temperature stability and threshold voltage will else be investigated. The total solutions on enhancement-mode AlGaN/GaN HEMTs with high performance, high threshold voltage and high stability will be provided, which can offer theory and technology support for high temperature stability enhancement-mode devices in AlGaN/GaN heterostructures transistors applications.

摘要：AlGaN/GaN异质结晶体管在功率器件、开关器件、高温、抗辐射等方面得到了良好的发展，其应用领域逐渐扩展到高稳定性数字电路等领域。FinFET器件结构在解决器件小尺寸效应方面有重大突破。本项重点研究FinFET结构结合薄势垒AlGaN/GaN异质结材料研制增强型器件及电路的实现方法和形成机理，具体研究内容包括：SiN层应力调制的的薄势垒AlGaN/GaN异质结材料研究；FinFET结构应用于AlGaN/GaN异质结增强型器件的器件结构设计优化；纳米量级栅宽的有源区低损伤、陡峭侧墙形貌刻蚀；纳米级栅长的实现以及欧姆区选择性刻蚀减小接触电阻提高频率特性；完整的E-D模兼容GaN数字电路工艺流程以及各类数字电路单元的实现和稳定性评价。采用变温、变频I-V、C-V测量，对器件、电路的形成机理和关键技术进行研究，实现高阈值电压、高稳定性的AlGaN/GaN异质结增强型器件和电路解决方案。

GaN基数字电路在武器、航空、航天等耐高温抗辐射领域，具有非常好的应用前景。本项目提出的三维栅控增强型GaN器件及电路技术，较好的解决了器件阈值电压稳定性问题，为耐高温抗辐射电路应用提供了较好的技术支撑。本项目完成了GaN基FinFET器件结构设计和仿真，GaN基FinFET器件研制和测试分析，GaN基数字电路的研制和测试分析，三个方面的研究内容。创新的提出了新的GaN基FinFET器件结构，并研制出了特性优良的GaN基FinFET器件，最后完成了GaN基数字电路的流片和测试。研制出的GaN基FinFET器件，在VGS-VTH= 2 V时的电流密度为500 mA/mm，跨导峰值达到370 mS/mm，器件的开关比为109，DIBL数值达到2 mV/V，击穿电压为138 V，器件fT达到22 GHz，fmax达到60 GHz。完成的数字电路单元均能实现各项预定的电路功能，倒向器噪声容限达到0.5V。本项目的支持下，发表项目资助论文8篇，获得受理专利2项，申请专利3项，培养研究生8名。本项目研究的基于GaN基FinFET结构的GaN基数字电路，具有阈值电压稳定，能抑制短沟道效应，耐高温抗辐射等特点，具有较好的学术和应用价值。