Method for fabricating a semiconductor device by high energy ion implantation while minimizing damage within the semiconductor substrate

摘要

A semiconductor device having superior electrical characteristics is fabricated. 50 nm of the surface of a CZ (100) silicon substrate is oxidized to form an oxidized film. Afterwards a first ion implantation of boron ions is conducted to this silicon substrate amounting to 7x1013 cm-2 with acceleration energy of 1.5 MeV. Next, a first annealing in nitrogen ambient at 1050 DEG C. for 40 minutes is conducted. Through this ion implantation process a damaged layer and a dopant layer are formed within the silicon substrate. Boron ions are implanted as a second ion implantation, with a dosage of 7x1013 cm-2, followed by a second implanted annealing in nitrogen ambient at 1050 DEG C. for 40 minutes. Further, as a third ion implantation, boron ions are implanted with a dosage of 6x1013 cm-2 followed by a third annealing in nitrogen ambient at 1050 DEG C. for 40 minutes. In the dopant layer thus formed, through a plurality of repeated high energy ion implantation and subsequent annealing, in order to obtain the desired dopant concentration, density of secondary defect occurrences may be lowered.