Selective enhancement of phosphorus diffusion by implanting halogen ions

摘要

An improved method of making bipolar monolithic integrated circuits by successive diffusions of boron and phosphorus. Selective halogen ion implantation is used to locally specifically enhance phosphorus diffusion. The halogen implant is performed prior to the boron diffusion. Enhanced local phosphorus diffusion provides selected transistors in the circuit with a narrower base width than others, and a corresponding higher current gain than others. Analogously, higher value pinch resistors can be selectively produced in the circuit.