0.15mm In0.4GaAs/In0.4AlAs Metamorphic HEMTís (M-HEMTís) Using A Novel Triple Shaped Gate Stgructure Assisted By PMGI Resist


Dae-Hyun Kim, Suk-Jin Kim, *Jaw-Hak Lee, *Ki-Woong Chung, and Kwang-Seok Seo


ISRC and School of Electrical Engineering and Computer Science (EecS), Seoul National University

San56-1, Shilim-Dong, Kwanak-Ku, 151-741, Seoul, Republic of Korea (ROK)

Phone: +82-2-880-5451(Ext. 237), Fax: +82-2-887-6575, Email, vtsrc3@hanmail.net

*WAVICS. Co. Ltd, F8 Telson Venture Tower, 949-3, Dokok-Dong, Kangnam-Ku, Seoul, Republic of Korea (ROK)


Keywords: M-HEMT, Cutoff-frequency (fT), PMGI, Fringing-capacitance, Triple-Gate


In this paper, a novel gate technology with triple shaped gate structure has proposed and developed in order to suppress unwanted gate fringing capacitance.Because high gate stem height was difficult to fabricate by means of conventional direct electron beam (E-Bean) lithography method, additional PMGI sacrificial layer was utilized in this new scheme.Increasing gate stem height as an amount of PMGI resist thickness and forming T-shaped gate structure on top of the PMGI layer, triple shaped gate structure could be finally obtained.Applying the developed technology to the fabrication to the fabrication of 0.15mm In0.4GaAs/In0.4AlAs metamorphic HEMTís (M-HEMTís) excellent device cutoff frequency (fT)

Performance of 147GHz even with .15mm technology has been shown owing to the remarkable reduction of gate fringing capacitance. In addition, the usage of 40% indium content in barrier layer gave rise to the improvements in Schottky gate characteristics such as gate turn-on voltage (Von) and reverse breakdown voltage (BVGD), which has important meanings in enhancement-mode operation devices.


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