High Yield, Highly Scalable, High Voltage GaInP/GaAs HBT Technology

Based on a power high-voltage (HV) HBT technology the successful down scaling towards low-power devices for mixed signal integrated circuits is described. Stress effects and mechanical stability issues required processing adaptations. High yields of 99.8 % for 3x30 μm 2 and 99.0% for 2x10 μm 2 HV-HBTs were achieved. This allows for fabrication of complex integrated circuits with several hundreds of transistors monolithically combining power and digital circuit parts. INTRODUCTION GaAs-based heterojunction bipolar transistors (HBTs) have been used for a wide range of microwave applications. Especially, the potential of GaAs HBTs with regard to power amplifiers for levels beyond 10 W has been verified, e.g. for application in base stations. This requires highly linear HBT power cells, which can be operated at collectoremitter voltages around 26V. Due to its superior reliability high performance HBT power cells provide specific solutions until new wide-band-gap technologies become really available [1]. We have developed GaInP/GaAs HBTs matching such high bias requirements (high-voltage HBT: HV-HBT) as already reported in [2, 3]. Currently, a mature high-voltage HBT processing is available at FBH: devices with 3μm GaAs collector and breakdown voltages BVCBO higher than 70 V are suitable for applications in the 1 3 GHz frequency range. Proprietary flip-chip mounted unit power cells with an emitter area of 4000 μm2 deliver output power levels higher than 10 W at 26 V with 12 dB gain and high efficiency (PAE > 60%) at 2 GHz [3]. The high reliability of HV-HBTs was proven by accelerated lifetime measurements as shown in fig.1. For a novel base station amplifier approach it was necessary to combine the power HV-HBTs with a digital circuit part. In order to avoid hybrid mounting we decided to use the HV-HBT technology for digital circuits, too. 0 50