Method for suppressing lattice defects in a semiconductor substrate

Abstract

A method for suppressing the formation of leakage-promoting defects in a crystal lattice following dopant implantation in the lattice. The process provides a compressive layer of atoms, these atoms having a size greater than that of the lattice member atoms. The lattice is then annealed for a time sufficient for interstitial defect atoms to be emitted from the compressive layer, and in that manner energetically stable defects are formed in the lattice at a distance from the compressive layer.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to the field of semiconductor fabrication. In particular, it relates to the fabrication of field effect transistors (FETs), involving the formation of semiconductor materials of selected conductivity, carried on by implantation of dopants.[0002]Fabrication of metal oxide semiconductor (MOS) FETs requires the formation of source and drain regions in a substrate of generally pure silicon (Si). The Si is provided in the form of a wafer, grown as a single crystal. Zones of the Si lattice are converted into regions of N or P conductivity by the addition of donor-type dopants, such as arsenic, for N regions, and acceptor-type dopants, such as boron, for P regions. These dopants are generally introduced by ion bombardment, in which ionized dopant atoms are energized and fired at the lattice, penetrating the crystal structure to a depth largely dependent on the bombardment energy and the ion mass.[0003]It can be immediately gath...

AI Technical Summary

Benefits of technology

[0004]An aspect of the claimed invention is a method for suppressing the formation of leakage-promoting defects in a crystal lattice following dopant implantation in the lattice. The process provides a compressive layer of atoms, these atoms having a size greater than that of the lattice member atoms. The lattice is then annealed for a time sufficient for interstitial defect atoms to be emitted from the compressive layer, and in that manner energetically stable defects are formed in the lattice at a distance from the compressive layer.

Problems solved by technology

It can be immediately gathered that such bombardment introduces crystal damage, in which lattice atoms are knocked out of lattice sites, while at the same time a certain number of the newly-introduced atoms will likewise come to rest in positions outside the lattice positions.

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