RF characteristics of BJT devices with selectively or fully ion-implanted collector

Abstract

A selectively ion-implanted collector (SIC) is implemented in a 0.8 um BiCMOS process to improve the RF characteristics of the BJT devices. The SIC BJT device has better ft and fmax than the FIC (fully ion-implanted collector) BJT device because the extrinsic base-collector capacitance is reduced by the SIC process. The fmax is 9.5GHz and ft is 7.8 GHz for the SIC BJT device while the fmax is 7.2 GHz and fmax is 4.5 GHz for the FIC BJT device when biased at Vce=3.6 V and Jc=0.09 mA/um(2). The nois parameters are the same for both BJT devices but the associated gain is higher for the SIC BJT device.