Process optimization for a complementary bipolar IC technology with 5.5-GHz fT pnp transistors

A complementary bipolar IC process has been developed featuring 9.0-GHz f_T npn and 5.5-GHz f_T pnp transistors. Process conditions for emitter, base, and collector of pnp transistors are optimized in order to achieve the best performance trade-off between current gain, early voltage, and cut-off frequency. With the optimized process conditions, the H_FE × V_A of the pnp transistor is 350 V with f_T of 5.5 GHz and f_max of 8.5 GHz. These high performance pnp transistors are integrated into an existing 9.0-GHz f_T npn bipolar process without introducing excessive additional process complexity or manufacturing cost. In addition, Schottky diodes, p-channel JFETs, and laser wafer trimmable precision NiCr resistors are integrated into the process to enhance analog circuit design capability