Electron Beam Lithography for Fabrication of Sub 250 nm T Gates for AlGaAs/InGaAs PHEMT Based MMICs
MMICs operating at 40 GHz and above require PHEMTs with T gates of dimensions 250 nm or less. We are presenting here a process to fabricate T gates using single step electron beam lithography process on a bilayer resist stack of PMMA and its methacrylic acid co-polymer P(MMA-MAA). Using this process we have fabricated T gates of dimensions up to 150 nm. One of the PHEMTs fabricated with 250 nm T gate have demonstrated cut off frequency of 53 GHz.
KeywordsT Gate PHEMT
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Authors are thankful to the Monolithic Microwave Integrated Circuit Fabrication Group of Solid State Physics Laboratory for fabricating the PHEMT device with 250 nm T gate whose RF measurement is presented in this work. Authors are also thankful to the Characterization Division of Solid State Physics Laboratory for carrying out the Scanning Electron Microscopy characterization of the samples.
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