200 nm gate-length GaAs-based MHEMT devices by electron beam lithography

GaAs-based metamorphic HEMTs （MHEMT） consist of GaAs substrates and InP-based epitaxial structure, and have the advantages of both InP HEMT＇s excellent performances and GaAs-based HEMT＇s mature processes. GaAs-based MHEMTs were applied to millimeter-wave low-noise, high-power applications and systems. The current gain cut-off frequency （fT） and the maximum oscillation frequency （fmax） are important performance parameter of GaAs-based MHEMTs, and they are limited by the gate-length mainly. Electron beam lithography is one of the lithography technologies which can be used to realize the deep submicron gate-length. The 200 nm gate-length GaAs-based MHEMTs have been fabricated by electron beam lithography. In order to reduce the parasite gate capacitance and gate resistance, a trilayer resist structure was used to pattern the T-gate resist profile. Excellent DC, high frequency and power performances have been obtained. FT and frnax are 105 GHz, 70 GHz respectively. The research is very helpful to obtain higher performance GaAs-based MHEMTso     

基于深紫外激光器的大面积干涉光刻装置研究

搭建了基于266 nm波长深紫外光源的干涉光刻装置，使用平顶光整形器将高斯光整形成平顶光束，在硅基底上制备出面积为8.9 mm×25.4 mm、周期为407 nm的一维光栅结构图形和周期为860 nm的二维孔洞结构。使用扫描电子显微镜（SEM）测量了平顶光产生的一维干涉结构的线宽、周期等参数，并与高斯光产生的一维干涉结构参数进行对比。实验结果表明，加入了平顶光整形器的干涉光刻装置产生的周期性光栅结构图形均匀性提升了21.36％。