A new self-aligned bipolar transistor using vertical nitride mask

A new polysilicon self-aligned bipolar n-p-n transistor structure is proposed, and this device is fabricated with 2.0 um design rules, which can be used in very high speed LSI circuits. The extrinsic base contact width of this n-p-n transistor is precisely controllable below 0.3 um, and it permits this device to have very high speed characteristics, which structure is obtained using vertical nitride mask. The mask has been achieved by the anisotropic plasma etching of nitride layer. Through all the process, the emitter of this device is not damaged, therefor a high performance device is obtained. The experimental circuit of CML ring-oscillator has per-gate minimum propagation delay time of 52 ps at 0.16 mW power consumption condition.