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Reactions in silicon–nitrogen plasma

Kovačević, Goran; Pivac, Branko (2017) Reactions in silicon–nitrogen plasma. Physical Chemistry Chemical Physics, 19 (5). pp. 3826-3836. ISSN 1463-9076

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Abstract

Reaction mechanisms that lead to creation of silicon–nitrogen bonds are studied in detail. These reactions are of fundamental importance for silicon nitride synthesis by plasma enhanced chemical vapour deposition from the gas mixture of silane (SiH4) and ammonia (NH3). All reactions in SiH4 –NH3 plasma can be categorised as some of the basic types of reactions: bond dissociation, neutral nucleophilic substitution, radical neutralisation, neutral–radical addition, silylene addition, silylene rearrangement, radical nucleophilic addition or hydrogen abstraction reaction. Energetics of these reactions is analysed in detail for a great number of reactions belonging to these categories, by using theoretical modelling. Geometry optimisations are carried out with the MP2/aug-cc-pVTZ level of theory and energetics is further determined with high level ab initio calculations at the CASPT2/aug-cc-pVTZ level, which enabled confirmation of relevance of several mechanisms as reactions that lead to silicon nitride growth from plasma enhanced chemical vapour deposition, as well as introduction of new, energetically favourable mechanisms. Besides amine radical assisted eliminative addition and proton transfer reactions, silylene addition reactions are thermodynamically and kinetically favourable since they lack energy barriers. A new reaction pathway for synthesis of silicon nitride from plasma is proposed. This pathway is enabled by the ability of silylene to create two weak dative bonds, which enables silylene–amine complexes to stick to the silicon nitride surface. Upon dissociation of amine from the surface-bound complex, silylene remains on the surface, available for reaction with other reactive species from plasma.

Item Type: Article
Uncontrolled Keywords: plasma; PECVD; ammonia, silane; reactions; reaction mechanisms; reaction enthalpy; CASPT2; silylene; bond dissociation; neutral nucleophilic substitution radical neutralisation, neutral-radical addition, silylene addition, silylene rearrangement, radical nucleophilic addition, hydrogen abstraction
Subjects: NATURAL SCIENCES > Physics > Atomic and Molecular Physics
NATURAL SCIENCES > Chemistry > Physical Chemistry
NATURAL SCIENCES > Chemistry > Theoretical Chemistry
NATURAL SCIENCES > Chemistry > Inorganic Chemistry
Divisions: Division of Materials Physics
Projects:
Project titleProject leaderProject codeProject type
Poluvodičke kvantne strukture za napredne sklopove-QD STRUCTURESBranko PivacIP-11-2013-6135HRZZ
Depositing User: Goran Kovačević
Date Deposited: 20 Jan 2017 08:48
Last Modified: 17 May 2017 14:13
URI: http://fulir.irb.hr/id/eprint/3327
DOI: 10.1039/C6CP05395E

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