Young Je Jo

Output power enhancement in AlGaN/GaN heterostructure field-effect transistors with multilevel metallization

To improve wafer utilization efficiency and heat dissipation performance, this paper proposes multilevel metallization-structured, lateral-type AlGaN/GaN heterostructure field-effect transistors (HFETs) on a 150 mm Si substrate using photosensitive polyimide (PSPI) as the intermetal dielectric layer. The maximum drain current of the HFETs is 46.3 A, which is 240% higher than that of conventional AlGaN/GaN HFETs with the same die size. Furthermore, the drain current drop of the HFETs under high-bias operation is reduced from 14.07 to 8.09%, as compared to that of conventional HFETs.

Bonding Pad Over Active Structure for Chip Shrinkage of High-Power AlGaN/GaN HFETs

This paper reports a bonding pad over active (BPOA) structure with photosensitive polyimide (PSPI) as the intermetal dielectric layer to reduce the chip size of high-power enhancement-mode AlGaN/GaN heterojunction FETs (HEFTs) on a 150-mm (6-in) Si substrate. The fabricated AlGaN/GaN HFETs with a BPOA structure exhibited a threshold voltage and a maximum current of 0.6 V and 38.6 A, respectively, at VGS of 6 V. The leakage current was 4.3 × 10-5 A at 700 V, which was the same value as that of the AlGaN/GaN HFETs without a BPOA structure. The reliability of the AlGaN/GaN HFETs with the BPOA structure during the packaging process was improved by the PSPI layer and a modified bonding pad structure, which endured the stress during the wedge wire bonding and epoxy molding processes.

In–Ga–Zn–O thin film transistor with HfO{sub 2} gate insulator prepared using various O{sub 2}/(Ar + O{sub 2}) gas ratios

We have investigated the effect of the deposition of an HfO{sub 2} thin film as a gate insulator with different O{sub 2}/(Ar + O{sub 2}) gas ratios using RF magnetron sputtering. The HfO{sub 2} thin film affected the device performance of amorphous indium–gallium–zinc oxide transistors. The performance of the fabricated transistors improved monotonously with increasing O{sub 2}/(Ar + O{sub 2}) gas ratio: at a ratio of 0.35, the field effect mobility of the amorphous InGaZnO thin film transistors was improved to 7.54 cm{sup 2}/(V s). Compared to those prepared with an O{sub 2}/(Ar + O{sub 2}) gas ratio of 0.05, the field effect mobility of the amorphous InGaZnO thin film transistors was increased to 1.64 cm{sup 2}/(V s) at a ratio of 0.35. This enhancement in the field effect mobility was attributed to the reduction of the root mean square roughness of the gate insulator layer, which might result from the trap states and surface scattering of the gate insulator layer at the lower O{sub 2}/(Ar + O{sub 2}) gas ratio.