Seung Hoon Sung

Experimental observation and physics of “negative” capacitance and steeper than 40mV/decade subthreshold swing in Al 0.83 In 0.17 N/AlN/GaN MOS-HEMT on SiC substrate

GaN is a promising material for LED lighting [1], high voltage power electronics [2] and high power RF applications [3]. GaN HEMT and MOS-HEMT with AlGaN [4] or AlInN [5] polarization layer have been widely studied. In this work we investigate the effects of Al_0.83In_0.17N polarization layer thickness scaling on the device characteristics of Al_0.83In_0.17N/AlN/GaN MOS-HEMTs on SiC substrates. We have experimentally observed “negative” capacitance and subthreshold swing (SS) steeper than 40 mV/dec in GaN MOS-HEMTs with thin Al_0.83In_0.17N polarization layer, where composition modulation of Al% and In% is observed.

Resistance and electromigration performance of 6 nm wires

A process to achieve 6 nm minimum dimension interconnect wires is realized using standard 193 nm lithography. Various metals including copper are optimized to gap fill features, and tested for electrical performance and reliability. Measurements showing line electrical resistance and electromigration as functions of material, conducting area, and interfaces are presented.

High-performance low-leakage enhancement-mode high-K dielectric GaN MOSHEMTs for energy-efficient, compact voltage regulators and RF power amplifiers for low-power mobile SoCs

We have fabricated L_G=90nm high-K dielectric enhancement-mode (e-mode) GaN MOS-HEMT which shows low I_OFF=70nA/μm (V_D=3.5V, V_G=0V), low R_ON=490Ω-μm, high I_D,max=1.4mA/μm, and excellent power-added efficiency (PAE) of 80% at RF output power density (RF Pout) of 0.55W/mm (V_D=3.5V, f=2.0GHz). These results represent (i) >3.6X lower RON at equivalent breakdown voltage (BV_D) than industry-standard Si voltage regulator (VR) transistors, and (ii) >10% better PAE at matched RF Pout or >50% higher RF Pout at matched PAE than industry-standard GaAs RF power amplifier (PA) transistors, all at mobile SoC-compatible voltages. These results make GaN MOS-HEMTs attractive for realizing energy-efficient, compact voltage regulators and RF power amplifiers for mobile SoC. This work shows, for the first time, that the application space of GaN electronics can be expanded beyond the existing high-voltage power and RF electronics (e.g. automobile, power conversion, base-station, radar) to include low-power mobile SoCs.

Simple test vehicle for metal fill and resistance of sub-8nm nanowire

Assessing metal gap fill capability and electrical behavior in patterned features ahead of full integration is valuable in interconnect process development as feature sizes scale beyond the 14 nm technology node. In this work a simple device is fabricated with existing silicon patterning recipes to achieve an electrical test vehicle that can test a range of metal candidates for interconnects. The vehicle is characterized using electron microscopy and electrical measurements.

Nickel silicide for interconnects

Nickel silicide is an attractive option for interconnects at small dimensions because of its short electron mean free path and good electromigration behavior. Nickel silicide interconnects can be integrated using either a subtractive or damascene process. Precise control of final metal composition ratio is important for obtaining low resistivity, as shown in thin-film and patterned structure measurements.