Advanced SOI MOSFETs with buried alumina and ground plane: self-heating and short-channel effects

摘要

SOI circuits exhibit excellent performance and scalability but suffer from self-heating. This critical problem is systematically analyzed by using an equivalent thermal circuit and 2-D simulations. We demonstrate that the thermal dissipation and self-heating in SOI MOSFETs can dramatically be improved by modifying the generic SOI Structure: replacement of the buried oxide with buried alumina. However, alumina is a high-K dielectric which also affects the electrical properties: the drain-to-substrate fringing fields are enhanced, leading to more severe short-channel effects. The trade-off between the thermal and electrical performance of very advanced SOI transistors (10-100 nm long, 5-100 nm thick) is examined by comparing various SOI materials and MOS architectures. The optimum solution consists of a ground plane located underneath a relatively thin buried alumina.