Enhanced Breakdown Voltage and Charge to Breakdown of Collector Implant-Gate Oxide-Poly Capacitors by Selective Epitaxial Growth

摘要

Poly to collector implant capacitors can be realized in any BiCMOS technology without additional process and mask steps. They are therefore very attraactive elements for mixed signal BiCMOS processes. For thin gate oxides below 150A the poor quality of the oxide grown on the collector due to the implant damage leads to unacceptable defet densities(above 10 cm~(-2)). By applying a thin selective epitaxial growth on the collector areas the crystal quality can be recovered. The improved oxide quality is resulting in low defect densities (better 0.1cm~(-2)) and nearly doubled breakdown voltage for the same specific capacity per unit area in a 90A gate oxide 0.5 um gate length process. The charge to breakdown (QBD) is increased by a factor of 10.