Preamorphization Induced Defects and their Effects on the Electrical Properties of Shallow p+/n Junctions

Shallow p⁺/n junctions are obtained by low boron or boron fluorine implantation into n-type silicon preamorphised substrate. Preamorphisation step was carried out by high dose Ge⁺ ion implantation at various energies ranging between 30 and 150 keV. The electrical characteristics of the diodes (reverse current density and noise spectral density) are shown to be strongly dependent on the preamorphisation Ge⁺ ion implantation energy. Combining electrical analysis with transmission electron microscopy allowed us to correlate the diode behaviour with the extended defects distribution induced by the regrowth of the amorphous layers. We report that these defects, usually named End-Of-Range, strongly affect the electrical performance when located within or close to the space charge region.