Low Temperature High Density Highly Uniform Si3N4 Technology for Passive and Active Devices in MMMIC Applications

In this work a novel, high quality, high-density, 100% yield, deposited at room temperature ultra thin 5nm Si3N4 Metal Insulator Metal (MIM) capacitor process for Monolithic Millimetre-wave Integrated Circuits (MMMICs) applications is demonstrated using inductively coupled plasma enhanced chemical vapor deposition technique (ICP-CVD). Capacitance of 6.7fF/μm and a breakdown electric field of more than 3x10Vcm were achieved. RF characterisation and equivalent circuits models were extracted which showed an increase in capacitance per area by more than thirteen fold and reduction in RF loss as silicon nitride thickness reduced from 120nm to 5nm. Comparison with high temperature conventional 300°C PECVD Si3N4 was also investigated, a comparable breakdown voltage, and leakage current was observed. We also present DC and RF results on 70nm T-gate SiGe MIS gate MODFETs using novel Si3N4 deposited at 22°C and lift-off techniques gate dielectric contact and its performance compared with devices made on the same chip using standard Schottky contact. This 5 nm Si3N4 gate dielectric enhanced the performance of gate leakage current and breakdown voltage.