Low-complexity full-melt laser-anneal process for fabrication of low-leakage implanted ultrashallow junctions

Good-quality ultrashallow n ⁺p junctions are formed using 5-keV amorphizing As ⁺ implantations followed by a single-shot excimer laser anneal for dopant activation. By using an implant that is self-aligned to the contact windows etched in an oxide isolation layer, straightforward processing of the diodes is achieved with postimplantation processing temperatures kept below 400°C. A possible source of junction leakage at the perimeter caused by dip-etch enlargement of the contact window, also confirmed by transmission electron microscopy (TEM) analysis, is identified, and diode performance is improved by increasing the junction/contact window overlap. The optimum performance in terms of low leakage, shallow junctions, and low resistivity is achieved for 30°tilted implants and by applying a thin laser-reflective aluminum layer. This work isolates the minimum requirements for achieving low-leakage diode characteristics.