A rapid thermal anneal (RTA) process has been investigated in detail for the applications of emitter diffusion and TiSi2 anneals in an advanced double-polysilicon bipolar process. The significance of thin oxide at the emitter-polysilicon-to-silicon interface for a low thermal budget process using RTA is presented in this paper. A change in wafer loading temperature from 400 to 600-degrees-C at emitter polysilicon deposition increased the emitter resistance from 30 to 700 OMEGA for emitter diffusion using RTA at 1025-degrees-C for 30 s. In contrast, emitter resistance of wafers that went through diffusion in a furnace at 1000-degrees-C for 15 min was insensitive to the wafer loading temperature at emitter polysilicon deposition. Such a large increase in emitter resistance for the RTA process is attributed to oxidation of the silicon surface during wafer loading at elevated temperatures at the emitter polysilicon deposition step. The interaction of RTA and subsequent heat cycles on the heavily doped polysilicon sheet resistance is discussed in the second section. Sheet resistance of arsenic- and boron-doped polysilicon increased by more than 50% when the wafers were annealed in a furnace at 800-degrees-C after the RTA emitter diffusion at 1050-degrees-C for 30 min. The reverse annealing was explained by the dopant deactivation from (i) segregation to grain boundaries and (ii) return to equilibrium concentration from supersaturation and dopant precipitation. The bipolar process employs an RTA heat cycle at 850-degrees-C for 10 s to transform the C49 phase of TiSi2 to the low resistivity C54 phase. The short RTA cycle resulted in superior silicide morphology and low contact resistance at the interface between TiSi2 and n+ polysilicon layers compared to a furnace anneal process.