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Contenu archivé le 2022-12-23

Hydrogen in silicon

Objectif



The semiconductor material most used for the manufacture of electronic devices is silicon. To make devices operate at higher speeds and consume less power they must be made smaller, and the control of impurities then becomes increasingly stringent. One impurity, which is now recognised as being increasingly important in silicon, is hydrogen. It is easy to contaminate silicon with hydrogen during many stages of processing. Hydrogen may combine with impurities which have been introduced intentionally, such as boron or phosphorus, making them electrically inactive. It can also be used to control the precipitation of oxygen in the process known as intrinsic gettering which is employed to clean metallic impurities out of the important areas of the silicon.

It is important that the properties of hydrogen in silicon are understood. Specifically, it is necessary to know the solubility of hydrogen and its mobility through the crystal. Both solubility and mobility will be affected by the presence of defects in the crystal, since some defects will act as traps for the hydrogen. These traps will stop the hydrogen from moving and will also act as storage points, enabling the solubility of the hydrogen to be increased over the (unknown) value for a perfect crystal. When the crystal is heated, hydrogen will be released from the traps, allowing further reactions in the silicon. The properties of the hydrogen are also likely to be greatly affected by the method by which it entered the crystal. For example, hydrogen which enters from a plasma is likely to be present along with radiation damage centres, in particular vacant lattice sites, with which the hydrogen will complex. In contrast, hydrogen introduced from a gas source may be free of these defects.

The joint research project will bring together three research teams to work on the properties of hydrogen. Each team has its own area of expertise, allowing complementarity in the work. Working contacts have been made in the recent past between the groups in London and Moscow, and between London and Aarhus, so that the foundations for a strong collaboration have been laid.

Specific aims are to study the behaviour of hydrogen in neutron-irradiated silicon, providing a controlled source of vacancies; mapping the distribution of hydrogen-related centres; and comparing different methods of creating hydrogen-related defects.

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Régime de financement

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Coordinateur

KING'S COLLEGE LONDON
Contribution de l’UE
Aucune donnée
Adresse
Strand
LONDON
Royaume-Uni

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Participants (2)