AlGaN_GaN低温无金欧姆接触电极及HEMT器件制备

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1、FabricationofAlGaN/GaNandlowtemperatureAu-freeohmiccontactelectrodeandHEMTDeviceADissertationSubmittedfortheDegreeofMasterCandidate：LiQixinSupervisor：Prof.WangHongSouthChinaUniversityofTechnologyGuangzhou,China摘要AlGaN/GaN异质结高电子迁移率晶体管（highelectronmobilitytransistors,HEMTs）在高压、高频、大功率半导体激光器以及高性能紫

2、外探测器等领域有广泛的应用前景。为降低AlGaN/GaNHEMTs制造成本，必须实现HEMTs与Si-CMOS器件工艺兼容。研究GaN基HEMTs低温无金欧姆接触技术，对提高HEMT器件可靠性和实现Si-CMOS工艺线的大规模制造，具有重要的实际意义。本文对AlGaN/GaN无金（Au-FREE）欧姆接触制备技术进行了深入研究，采用Ti/Al/Ti/TiW作为无金欧姆金属，研究设计了AlGaN/GaNHEMTs无金欧姆接触电极结构和工艺，分析了欧姆前刻槽深度和退火合金条件对Si基AlGaN/GaN异质结无金欧姆接触特性的影响，制备完成了AlGaN/GaN低温无金欧姆接触电极。实验结

3、果表明：当刻槽深度为22nm时，较薄的势垒层厚度和较大的隧穿面积使电子隧穿得到极大的提高，低温退火(600℃)的无金欧姆接触电学特性明显优于无欧姆前刻槽高温退火的无金欧姆接触。低温退火无金欧姆接触的电阻和比接触电阻率ρ-52c(5.44×10Ω·cm)与高温退火的有金(Au-based)欧姆接触相当，而电极退火后的均方根(RMS)表面粗糙度仅为3.69nm。在此基础上制备出无金欧姆接触电极的AlGaN/GaNMIS-HEMTs器件，测试结果表明，器件的源漏饱和电流密度为468.5mA/mm@VG=4V，阈值电压为-8V，具有良好的输出特性和转移特性。低温无金器件样品的击穿电压（10

4、3V）比高温退火的有金器件样品的击穿电压（70V）高。因此，采用无金工艺制备的AlGaN/GaNMIS-HEMTs器件，有助于减少器件由于高温退火等因素引起的漏电，提升器件的击穿电压和可靠性。关键词：AlGaN/GaNHEMTs；无金欧姆接触；低温合金；欧姆前刻槽IABSTRACTAlGaN/GaNheterojunctionhighelectronmobilitytransistorhighelectronmobilitytransistors(HEMTs)hasbeenwidelyusedinhighvoltage,highfrequency,highpowersemicond

5、uctordevicesandhighperformanceultravioletdetectors.InordertoreducethemanufacturingcostsofAlGaN/GaNHEMTs,theprocesscompatibilitybetweenHEMTsandSi-CMOSdevicesmustberealized.Itisofgreatsignificancetostudythelow-temperatureAu-freeohmiccontacttechnologyofGaN-basedHEMTsforimprovingthereliabilityofHE

6、MTdevicesandrealizingthelarge-scalemanufactureofSi-CMOSprocessline.Inthispaper,theAlGaN/GaNAu-freeohmiccontacttechnologyisstudies.UsingTi/Al/Ti/TiWasAu-freeohmicmetal,thestructureandprocessofAlGaN/GaNHEMTsAu-freeohmicelectrodehavebeendesigned.Theeffectsofthedepthofpre-ohmicrecessandtheannealin

7、gconditionontheAu-freeohmiccontactcharacteristicsofSi-AlGaN/GaNheterojunctionwereanalyzed.TheAlGaN/GaNlowtemperatureAu-freeohmiccontactelectrodehasbeenprepared.TheexperimentalresultsshowthatWhenthepre-ohmicdepthis22nm,thethicknessofthin