High quality shallow p/sup +/-n junction formation by employing BF/sub 2//low energy /sup 11/B mixed ion implant process

BF/sub 2//low energy /sup 11/B mixed ion implantation has been investigated as a new method of forming high quality shallow p/sup +/-n junctions and compared with other methods such as conventional BF/sub 2/ ion implantation and /sup 73/Ge pre amorphization prior to /sup 11/B or BF/sub 2/ implantation. The mixed ion implantation produced significantly lower junction leakage current than the conventional BF/sub 2/ ion implantation and the /sup 73/Ge preamorphization process, which is attributed to reduction of implantation-induced damage while maintaining the advantage of BF/sub 2/ ion implantation. In addition, the sheet resistance of p/sup +/-n junction and saturation current of a short channel PMOSFET were improved without causing any other deteriorative effect on transistor performance.