The formation of multilayer resist mask for transistor T-gates fabrication using electron-beam lithography

The processes of T-gate fabrication with gate “foot” length up to 150 nm using multilayer resist mask were investigated in the paper. The possibility of production of required gate shape using two-layer resist stack 950K PMMA/EL-11, tri-layer resist stack PMMA/LOR 5B/495 PMMA that was used to improve a “lift-off” quality and also four-layer resist stack EL-6/ PMMA 950K/ LOR 5B/ PMMA 495K that was used to produce transistors with wide recess in the same lithographic process with gate fabrication was studied. The patterns, optimal exposure doses, developers and development conditions were chosen for all masks.