LAYERED-OXIDE-ISOLATION (LOXI) METAL-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR (MESFET) FOR LOW PARASITIC SOURCE-DRAIN CAPACITANCE

We proposed and successfully fabricated a novel metal-semiconductor fi eld effect transistor (MESFET) which is called as layered-oxide-isolat ion (LOXI) MESFET. In this structure, the channel is isolated from the semi-insulating (SI) GaAs substrate by a low dielectric constant (eps ilon) material such as silicon dioxide. In order to realize this struc ture, we used a low-temperature wafer-bonding technique. Using this te chnique, it was possible for two 3-inch-diameter wafers to bond with e ach other at a temperature lower than 300 degrees C. Thermal stability was kept at temperature higher than 420 degrees C. In fabricated 0.5 mu m-gate-length LOXI-MESFETs, transconductance g(m) of 135 mS/mm, whi ch is same as that for a conventional MESFET, and good pinch-off chara cteristics were obtained, demonstrating the feasibility of the fabrica tion process.