基于湿法腐蚀凹槽阳极的低漏电高耐压AlGaN/GaN肖特基二极管  

Low leakage current and high breakdown voltage of AlGaN/GaN Schottky barrier diodes with wet-etching groove anode

作　　者：武鹏[1] 朱宏宇 吴金星 张涛[1] 张进成[1] 郝跃[1] Wu Peng;Zhu Hong-Yu;Wu Jin-Xing;Zhang Tao;Zhang Jin-Cheng;Hao Yue(National Key Laboratory of Wide Band Gap Semiconductor Devices and Integrated Technology,Xidian University,Xi’an 710071,China;Chinese Flight Test Establishment,Xi’an 710089,China)

机构地区：[1]西安电子科技大学,宽禁带半导体器件与集成电路全国重点实验室,西安710071 [2]中国飞行试验研究院,西安710089

出　　处：《物理学报》2023年第17期364-370,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62104185);国家杰出青年科学基金(批准号:61925404);中央高校基本科研业务费(批准号:QTZX23076);青年人才托举工程(批准号:2022QNRC001)资助的课题.

摘　　要：得益于铝镓氮/氮化镓异质结材料较大的禁带宽度、较高的击穿场强以及异质界面存在的高面密度及高迁移率的二维电子气,基于该异质结材料的器件在高压大功率及微波射频方面具有良好的应用前景,尤其是随着大尺寸硅基氮化镓材料外延技术的逐渐成熟,低成本的氮化镓器件在消费电子方面也展现出极大的优势.为了提高铝镓氮/氮化镓肖特基二极管的整流效率,通常要求器件具有较小的开启电压、较低的反向漏电和较高的击穿电压,采用低功函数金属阳极结构能有效降低器件开启电压,但较低的阳极势垒高度使器件易受界面缺陷的影响,导致器件反向漏电增大.本文采用一种新型的基于热氧氧化及氢氧化钾腐蚀的低损伤阳极凹槽制备技术,解决了常规干法刻蚀引入的表面等离子体损伤难题,使凹槽表面粗糙度由0.57 nm降低至0.23 nm,器件阳极反向偏置为-1 kV时的漏电流密度由1.5×10^(-6) A/mm降低至2.6×10^(-7) A/mm,另外,由于热KOH溶液对热氧氧化后的AlGaN势垒层及GaN沟道层具有良好的腐蚀选择比,因此避免了干法刻蚀腔体中由于等离子体分布不均匀导致的边缘刻蚀尖峰问题,使器件反向耐压由-1.28 kV提升至-1.73 kV,器件性能得到极大提升.AlGaN/GaN heterojunction epitaxies with wide bandgap,high critical electric field as well as high density and high mobility two-dimensional electron gas have shown great potential applications in the next-generation high-power and high-frequency devices.Especially,with the development of Si-based GaN epitaxial technique with big size,GaN devices with low cost also show great advantage in consumer electronics.In order to improve the rectification efficiency of AlGaN/GaN Schottky barrier diode(SBD),low leakage current and low turn-on voltage are important.The GaN Schottky barrier diode with low work-function metal as anode is found to be very effective to reduce turn-on voltage.However,the low Schottky barrier height makes the Schottky interface sensitive to damage to groove surface,which leads to a high leakage current.In this work,a novel wet-etching technique with thermal oxygen oxidation and KOH corrosion is used to prepare the anode groove,and the surface roughness of groove decreases from 0.57 to 0.23 nm,compared with that of the dry-etching surface of groove.Meanwhile,the leakage current is suppressed from 1.5×10^(-6) to 2.6×10^(-7) A/mm.Benefiting from the great corrosion selectively of hot KOH solution to AlGaN barrier layer and GaN channel layer after thermal oxygen oxidation,the spikes of the edge of groove region caused by the nonuniform distribution of plasma in the cavity is improved,and the breakdown voltage of the fabricated AlGaN/GaN SBDs is raised from -1.28 to -1.73 kV.

关 键 词：铝镓氮/氮化镓 肖特基二极管 低反向漏电 高击穿电压 

分 类 号：TN311.7[电子电信—物理电子学]