A new self-alignment technology for sub-quarter-micron-gate FETsoperating in the Ka-band

A self-alignment technology is proposed that allows fabrication of gates of less than 100 nm using conventional optical lithography. An offset gate structure is realized using this method. The technology is applied to high-power GaAs MESFETs consisting of many individual FETs. The uniformity of the FET characteristics is checked to show reproducibility. The input-output power characteristics of a MESFET with a 3.6-mm gate width were measured at 28 GHz. A linear gain of 4.0 dB and a saturation power of 0.8 W were obtained, demonstrating the overall effectiveness of this technology. It is shown that a 50-nm gate can be fabricated with this technology. A MESFET with a 90-nm gate length that was fabricated and evaluated at high frequency to demonstrate the technology is discussed