基于铁电薄膜HfZrO/Al2O3叠层栅介质的增强型GaN基MFS-HEMT器件研究

The project mainly focuses on the fabrication and modeling of enhanced GaN-based MFS-HEMT devices based on ferroelectric thin film HfZrO/Al2O3 stacked gate dielectrics. Develop the growth mechanism of ferroelectric thin film HfZrO/Al2O3 deposition by plasma enhanced atomic layer device (PEALD), the interface defects of ferroelectric thin films and III-V semiconductors, and the mechanism of depolarization, and finally improve the ferroelectric thin film and III-V semiconductor interface quality. By studying the influence of polarization characteristics of ferroelectric thin films on the polarization characteristics of GaN heterojunction, the ferroelectric thin film growth process is optimized, and a ferroelectric thin film with a specific polarization direction and polarization strength is obtained. From the aspects of material physics, device structure and device mechanics, the effects of the negative capacitance effect, electrical hysteresis curve, and interface charge on the polarization electric field of ferroelectric thin films and GaN heterojunctions in GaN MFS-HEMT devices are established. physical models is established that accurately describe different structures of ferroelectric materials and GaN device devices. To overcome the key processes of gate trench etching and ohmic contact of devices and develope a complete process for GaN MFS-HEMT devices.

项目开展基于铁电薄膜HfZrO/Al2O3叠层栅介质的增强型GaN金属-铁电材料介质-半导体-高电子迁移率晶体管（GaN MFS-HEMT）制备和模型等研究。开展等离子体增强原子层设备沉积铁电薄膜HfZrO/Al2O3的生长机制，铁电薄膜与III-V族半导体界面缺陷以及退极化的产生机理，以及改善铁电薄膜与III-V族半导体界面质量等方面的研究。通过研究铁电薄膜的极化特性对GaN异质结本身的极化特性的影响，优化铁电薄膜生长工艺，获得特定极化方向和极化强度的铁电薄膜。从材料物理、器件结构以及器件机理等多方面入手，通过研究GaN MFS-HEMT器件的负电容效应、电滞回曲线以及界面电荷对铁电薄膜和GaN异质结极化效应的影响，建立准确描述不同结构的铁电材料与GaN材料器件器件的物理模型。攻克器件的栅槽刻蚀、欧姆接触等关键工艺，开发出GaN MFS-HEMT器件的完整工艺。

本项目对铁电薄膜HfZrO/Al2O3栅介质GaN金属铁电介质半导体结构高电子迁移率晶体管(MFSHEMT)铁电极化、模型和制备工艺开展了相关的研究，分别研究了HfZrO铁电薄膜的不同组分、不同厚度、退火条件以及等离子体钝化等方面对HfZrO铁电薄膜极化特性和电学特性的影响。通过优化设计HfZrO/Al2O3铁电薄膜的结构，生长出高剩余极化、高介电常数、稳定可靠的10 nm Hf0.5Zr0.5O2/1.7 nm Al2O3铁电薄膜，在常温下测试剩余极化值2Pr达到46.2 µC/cm2，相比于10 nm Hf0.5Zr0.5O2提升了约21%。采用氮等离子体处理HfZrO薄膜的TiN金属电极，使HfZrO薄膜电容界面氧空位降低了27 %，从而抑制了HfZrO薄膜的唤醒效应和疲劳效应。通过研究GaN MFSHEMT中AlxGa1-xN势垒层厚度和Al组分结构对HfZrO/Al2O3/AlGaN/GaN MFSHEMT极化特性和电学性能的影响，建立了MFSHEMT器件的铁电极化理论以及物理模型。优化AlxGa1-xN势垒层厚度和Al组分结构，改善了AlGaN/GaN极化效应对HfZrO/Al2O3铁电极化的钉扎效应，提高了GaN MFSHEMT的铁电极化和二维电子气密度。开展了GaN MFSHEMT器件制备关键工艺的研究。基于Ti/Al/Ti/Au欧姆接触系统在GaN MFSHEMT器件制备中的应用研究，在850 ℃/30 s的合金条件下，得到了1.01×10-5 Ω·cm2的低欧姆接触电阻率。开发了HfZrO/Al2O3/AlGaN/GaN MFSHEMT器件完整工艺流程，制备了12 nm Hf0.5Zr0.5O2/1.7 nm Al2O3栅介质GaN HEMT器件，测试与分析了器件的性能。与8 nm Al2O3栅介质 GaN MISHEMT器件相比，12 nm Hf0.5Zr0.5O2/1.7 nm Al2O3栅介质GaN MFSHEMT器件的驱动电流、开关电流比和跨导分别提高了15 %，27 %和8 %。此项成果可以为低功耗GaN器件集成芯片提供必要的创新思路、理论基础和技术储备。