Abstract:
A semiconductor device including a MOS field effect transistor formed on a single silicon crystal substrate having source and drain diffused regions of reduced depth. In order to avoid penetration of aluminum from the aluminum connector through the diffused region into the substrate, the diffused region is formed by double diffusion of at least two types of impurities of the same conductive type, but having different diffusion coefficients with respect to each other.
Abstract:
A SUBCOLLECTOR WINDOW IS OPENED IN AN OXIDE COVERED P- SIALICON SUBSTRATE. TWO N DOPANTS OF DIFFERENT DIFFUSION RATES (ARSENIC AND PHOSPHOROUS) ARE DIFFUSED THROUGH THE WINDOW INTO THE SUBSTRATE. THE OXIDE COVERING IS REMOVED AND A P- SILICON EPITAXIAL LAYER IS DEPOSITED ON THE SUBSTRATE AND REOXIDIZED. DURING THE REOXIDATION CYCLE, THE PHSOPHOROUS AND ARSENIC ARE OUT-DIFFUSED, THE PHOSPHORUS REACHING THE TOP SURFACE OF THE EPITAXIAL LAYER TO PRODUCE AN N POCKET IN THE P- EPITAXIAL LAYER AND SUBSTRATE, THE POCKET HAVING A HEAVILY DOPED N+ REGION ADJACENT THE
EPITAXIAL LAYER-SUBSTRATE INTERFACE. BASE AND EMITTER DIFFUSIONS ARE MADE WITHIN THE N POCKET TO FORM A TRANSISTOR.