Influence of substrate-boron concentration on the residual end-of-range defects in 450 °C annealed As+-implanted junctions

Abstract

Evolution of the crystallographic position of As impurities in heavily doped Si crystals as their electrical activity changes Appl.In order to clarify the origin of enhanced leakage currents observed in As ϩ -implanted junctions annealed at a temperature as low as 450°C ͓M. M. Oka, A. Nakada, K. Tomita, T. Shibata, T. Ohmi, and T. Nitta, Jpn. J. Appl. Phys. 34, 796 ͑1995͔͒, two-step implantation/anneal experiments have been conducted and the spatial distribution of end-of-range defects has been investigated. As a result, it has been demonstrated that the residual damage in 450°C annealed junctions is strongly influenced by the doping level of p-type silicon substrate. The defects were found deeply distributing in the substrate, i.e., about 350 nm below the silicon surface when the doping level was 2.5ϫ10 15 cm Ϫ3 . The defect distribution further extends for higher boron doping levels. Taking these experimental results into account, As ϩ -implanted n ϩ p junctions were formed on substrates having varying doping levels. About two orders of magnitude reduction in the leakage current was observed with decrease in the substrate boron concentration from 10 16 to 10 14 cm Ϫ3 . For low boron concentration of 1.6ϫ10 14 cm Ϫ3 , the leakage current level as low as 1.7ϫ10 Ϫ9 A/cm 2 has been achieved by a 450°C postimplantation annealing.

Low Leakage Current and Low Resistivity p+n Diodes on Si(110) Fabricated by Ga+ and B+ Dual Ion Implantation for Low Temperature Source–Drain Activation

“…The principle of source-drain activation by low temperature annealing is a solid phase epitaxial regrowth (SPER) of the amorphous layer fabricated by the ion implantation. [5][6][7][8][9][10] Furthermore, the improvement of metal-oxide-semiconductor field-emission transistors (MOSFETs) current drivability without shrinking is also important in order to improve LSI performance. It has been shown that the current drivability of MOSFET is vastly improved by making the device on Si(110) surface.…”