Recent high-speed bipolar technologies based on SICOS (Sidewall Base Contact Structure) transistors are reviewed. Bipolar device structures that include polysilicon are key technologies for improving circuit characteristics. As the characteristics of the upward operated SICOS transistors are close to those of downward transistors, they can easily be applied in memory cells which have near-perfect soft-error-immunity. Newly developed process technologies for making shallow base and emitter junctions to improve circuit performance are also reviewed. Finally, complementary bipolar technology for low-power and high-speed circuits using pnp transistors, and a quasi-drift base transistor structure suitable for below 0.1 µm emitters are discussed.