0.15-µm T-Shaped Gate MODFETs Using BCB as Low-k Spacer

Yoshiharu ANDA  Katsuhiko KAWASHIMA  Mitsuru NISHITSUJI  Tsuyoshi TANAKA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E84-C    No.10    pp.1323-1327
Publication Date: 2001/10/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Joint Special Issue on Heterostructure Microelectronics with TWHM 2000 (Topical Workshop on Heterostructure Microelectronics 2000))
Category: Hetero-FETs & Their Integrated Circuits
Keyword: 
GaAs,  MODFET,  BCB,  millimeter wave,  low-k,  

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Summary: 
We report 0.15-µm T-shaped gate MODFETs using BCB (Benzocyclobutene) as low-k spacer dielectric material. The RF performance of pseudomorphic MODFET was improved by reducing the gate fringing capacitance using low-k material. The BCB film was deposited by plasma CVD technique at 100C and was patterned by lift-off technique. The dielectric constant of BCB film deposited by plasma CVD was confirmed 2.7, which is equal to that of spin-coated BCB, and is 35% lower than that of conventional SiO2. The leakage current was 4.710-5 A/cm2 at 3.6 MV/cm and was low enough for spacer material. 0.15-µm T-shaped gate MODFETs were fabricated by using BCB spacer and phase-shift lithography technique. More than 20 GHz increase of fmax was obtained in comparison with conventional SiO2 spacer by reducing the gate fringing capacitance.