Wafer-Scale, Sub-5 nm Junction Formation by Monolayer Doping and Conventional Spike Annealing

TL;DR

This paper demonstrates a wafer-scale method for creating ultrashallow sub-5 nm junctions in silicon using monolayer doping combined with conventional spike annealing, achieving high dopant activation and minimal leakage.

Contribution

It introduces a novel monolayer doping technique for ultrashallow junctions that is scalable and does not induce defects, with detailed characterization and process insights.

Findings

70% dopant activation efficiency

Minimal junction leakage currents (<1 uA/cm2)

Wafer-scale uniformity limited by annealing temperature homogeneity

Abstract

We report the formation of sub-5 nm ultrashallow junctions in 4 inch Si wafers enabled by the molecular monolayer doping of phosphorous and boron atoms and the use of conventional spike annealing. The junctions are characterized by secondary ion mass spectrometry and non-contact sheet resistance measurements. It is found that the majority (~70%) of the incorporated dopants are electrically active, therefore, enabling a low sheet resistance for a given dopant areal dose. The wafer-scale uniformity is investigated and found to be limited by the temperature homogeneity of the spike anneal tool used in the experiments. Notably, minimal junction leakage currents (<1 uA/cm2) are observed which highlights the quality of the junctions formed by this process. The results clearly demonstrate the versatility and potency of the monolayer doping approach for enabling controlled, molecular-scale ultrashallow junction formation without introducing defects in the semiconductor.