Monolithic bipolar SCR memory cell

摘要

Bipolar memory arrays having lower quiescent leakage and higher switching speed are constructed by using coupled SCRs formed from vertical PNP and NPN devices. Buried collectors for the PNP and NPN devices are provided within the same isolation tub. A P type plug is used to connect the P collector of the PNP to the P base of the NPN in a region where the P base and P collector overlap. A single N epi-region serves as the base of the PNP and the collector of the NPN. The P plug is located within this N epi-region but part of the N epi-region adjacent to or around the P plug is left so that internal connection of the PNP base and NPN collector is not cut off by the P plug. The structure is particularly suited for use in large memory arrays. The method of fabrication is also described.