SiGeHBTs on bonded wafer substrates

Silicon germanium (SiGe) heterojunction transistors have been fabricated on bonded wafer, silicon-on-insulator (SOI) substrates. The devices have application in low power, radio-frequency electronics. The bonded wafer substrates incorporate poly-Si filled, deep trenches for isolation. A novel selective and non-selective low pressure chemical vapour deposition (LPCVD) growth process was used for the epitaxial layers. Experimental transistors exhibit good uniformity across the wafers and collector currents are seen to be ideal, showing the expected enhancement for the SiGe devices compared to Si. Anomalies in device characteristics at high current levels are investigated. (C) 2001 Elsevier Science B.V. All rights reserved.