A well concept for field implant free isolation and width independent n-MOSFET threshold and reliability

Boron segregation effects in the p-well during field oxidation can be compensated by splitting the well drive-in into two parts before and after field oxidation. In consequence sufficient field isolation can be achieved without channel stop implants even for moderate well implantation doses, keeping parasitic junction capacitances and body factors low. The smaller doping gradient between field and active areas leads to nearly neutral transistor-width dependence and width independent n-channel degradation.