The fabrication of T-gate structures using a bilayer resist scheme of PMMA 495K molecular weight (4% solids) and PMMA 950K molecular weight (3~ solids) for use with electron beam exposure was investigated. The 1.18 sensitivity ratio between these resists was found to be insufficient to adequately provide the resist cavity necessary for fabrication of T-gate aluminum structures.
Lehner, Eric A.
"Fabrication of T-Gate Structures Using Double Layer E-Beam Lithography,"
Journal of the Microelectronic Engineering Conference: Vol. 5
, Article 14.
Available at: http://scholarworks.rit.edu/ritamec/vol5/iss1/14