Devolopment of high thermal conductivity buried oxide materials for minimizing self-heating effect in SOI substrates.

摘要

The self-heating effect is known to strongly affect the performance of modern silicon-on-insulator (SOI) devices. This study evaluates new high thermal conductivity buried oxide (BOX) layers for minimizing the self-heating effect in next generation SOI technology, particularly for mixed-signal applications. High thermal conductivity dielectrics such as Si3N4, Al2O3, AlN, diamond-like carbon (DLC) and diamond were selected as candidate buried oxide (BOX) materials to replace the conventional SiO2 BOX layer. These candidate BOX materials were characterized in terms of their electrical, physical and thermal properties.;The 3o and transient thermal reflectance (TTR) methods were used to measure the thermal conductivity of various thin films in this study. By applying two independent methods to identical samples, a more reliable thermal analysis was achieved. Among candidate BOX materials, AlN films show the highest thermal conductivity of 7 W/m˙K. All BOX materials under test showed much lower thermal conductivities than their bulk values because phonon scattering near the interface becomes dominant when the film thickness is comparable to the wavelength of the phonon.;Thermal imaging has been introduced as an effective technique to investigate the heat dissipation efficiency through the BOX materials. The highest heat dissipation efficiency of 42% was obtained from 260 nm-thick Diamond films compared to 400 nm-thick SiO2 films. Heat dissipation efficiencies of 34% for 400 nm-thick AlN, 21% for 260 nm-thick Al2O3, 19% for 400 nm-thick Si3N4, and 3.6% for 380 nm-thick DLC were obtained.;Fabrication of high thermal conductivity (HTC) SOI substrates was explored using the ion-cut process. The bondability of each material using corresponding bonding processes was investigated. Thermal imaging on the fabricated AlN-BOX SOI and Si3N4-BOX SOI showed 40 % and 15% better heat reduction compared to conventional SOI, respectively. The results suggest that a high thermal conductivity SOI substrate can significantly reduce the self-heating effect.