电子束实现210 nm栅长115 GHz GaAs基mHEMT器件

210 nm T-gates of GaAs-based HEMT with f_(max)=115 GHz by one-step E-beam lithography approach

为了获得T型栅应变高电子迁移率晶体管(m HEMT)器件,利用电子束(Electron beam,E-beam)光刻技术制备了210 nm栅长,减小m HEMT器件栅极的寄生电容和寄生电阻。采用PMMA A4/PMMA-MMA/PMMA A2三层胶电子束直写的方法定义了210 nm栅长T型栅极。In Al As/In Ga As异质结Ga As-m HEMT器件的直流特性和高频特性分别通过Agilent B1500半导体参数分析仪和Agilent 360 B矢量网络分析仪测试。直流测试结果显示,210 nm栅长In Al As/In Ga As沟道Ga As-m HEMT单指器件的最大有效输出跨导(gm:max)为195 m S/mm,器件最大沟道电流160 m A/mm。射频测试结果显示,电流增益截至频率(fT)和最高振荡频率(fmax)分别为46 GHz和115 GHz。同时欧姆电极特性和栅极漏电特性也被表征,其中栅极最大饱和漏电流密度小于1×10-8 A/μm。

A conventional tri-layer resist structure which consists of PMMA A4/PMMA-MMA/PMMA A2 is adopted to pattern the 210 nm T-gate resist profile in a single lithographic step and a single development step,in order to fabricate the T-shaped gate InAlAs/InGaAs metamorphic High Electron Mobility Transistors(mHEMTs)on a GaAs substrate.The DC and microwave performance of the device are characterized on wafer by an Agilent B1500 semiconductor parameter analyzer and an Agilent 360 B Vector Network Analyzer under room temperature,respectively.The mHEMT device shows the DC output characteristics having an extrinsic maximum transconductance g m:max of 195 mS/mm and the full channel current of 160 mA/mm.The cut-off frequency f T and the maximum oscillation frequency f max for the mHEMT device with gate width of 50μm are 46 GHz and 115 GHz,respectively.Meanwhile,work has also been carried out to determine the quality of the Ti/Pt/Au Schottky contact to InAlAs with remarkably small gate leakage current in the order of 1×10-8 A/μm,which is extremely useful for the reduction of shot noise and the LNA applications.