| dc.description.abstract | This study aims to fabricate deep sub-micron AlInGaN/AlN/GaN high electron mobility transistors grown on silicon substrate using i-line optical lithography processes. Using an i-line stepper from Taiwan Semiconductor Research Center and plasma-enhanced chemical vapor deposition (PECVD) SiNx backfill process, devices with gate length of 0.25 μm or less are fabricated for the application in millimeter wave power amplifiers.
The fabrication process of the 0.25 μm T-gate devices is described as the following. The original 0.7 μm gate foot is successfully shrunk to 0.25 μm by etching the backfilled SiNx, which not only has the function of scaling gate length, but also supporting the gate head to avoid yield loss. Drain current under zero-gate bias (Idss) of 537 mA/mm, maximum transconductance (gm,max) of 439 mS/mm, and current gain cutoff frequency (fT) up to 58 GHz, and power gain cutoff frequency (fmax) of 73 GHz, have been achieved. At 28 GHz and 6 GHz, output power density (Pout) of 0.68 W/mm and 1.78 W/mm, and power added efficiency (PAE) of 5.92 % and 26.93 %, have also been demonstrated, respectively.
This thesis also details the method of using ICCAP and ADS software to construct the small signal model of the devices with factors, such as device processing, layout design, epitaxial structure and effect of substrate, considered in the equivalent circuit. The correlation between device high frequency characteristics and the extracted parameters is analyzed. | en_US |