 The primary challenge in fabricating such structures is achieving satisfactory self-alignment between the upper and lower gates.20 years after the MOSFET was first demonstrated by Mohamed Atalla and Dawon Kahng of Bell Labs in 1960, the concept of a double-gate MOSFET was proposed by Toshihiro Sekigawa of the Electrotechnical Laboratory (ETL) in a 1980 patent describing the planar XMOS transistor.Sekigawa fabricated the XMOS transistor with Yutaka Hayashi at the ETL in 1984.