Enhanced thermal performance of lifted AlGaAs HBT's bonded onto natural diamond substrates

Abstract

The IC industry lias rcaclicd tlic tlircsliold wlicrc tlic device pcrformance is limitcd by traditional packaging concepts. For instance, tlie trend toward higher frequcncy operation of GaAs/AlGaAs Iieterqjunction bipolar transistors (HBT) lias manifested itself in the ever increasing nced for ncw packaging systems in ordcr to lower tlie thermal resistance ’I?. In particular. devices grown on semi-insulating GaAs substrates suffer to ii grcalcr cstcnt due to the poor thermal conductivity of 111-V compounds. In Silicon IC technology, liowevcr. llicse limitations are not as severe. due to the approsinlately 2.7 tiines larger thermal conductivity of Si respect to GaAs. Nevertheless, recent developments in thin film handling and processing technology have created new vistas for inovative packaging solutions. For esamplc, using tlie epitasial liftoff (ELO) technique ’. active layers of clcctronic circuitry can be isolated from their substrates on which they were synthesized and hrtl ier mounted onto diffcrcnt substratcs with suitable thermal properties.