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Title: Chemical strategies for removal of trace impurities from gases and solvents.
Author: Leggett, Graham
Awarding Body: Queen Mary, University of London
Current Institution: Queen Mary, University of London
Date of Award: 1997
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Several aspects of gas purification for the semiconductor industry are reviewed; these include the production of integrated circuits, semiconductor gases and the impurities found therein, determination of trace impurities, and finally point-of-use purification methods. In the course of work aimed at deducing the potential of aluminium amides as metallo organic purifiers for semiconductor gases three novel compounds were isolated and characterized. The crystal structure of each of these compounds has been determined. The first of these compounds, [AI(i-C4H9)]2[CgH2oN6][AI(i-C4H9)2b was prepared via the reaction of triisobutylaluminium with diethylenetriamine. The second compound" [AICI] [CgH2oN4] [AI(N(CH3)2)CI][AI(N(CH3)2)2] , was isolated from a reaction of [AI(NMe2)3]2 with dimethylethylenediamine. Finally the adamantane-like AI4CI2[N(CH3)2]6(NCH3)O was isolated from a reaction of [AI(NMe2)3]2 with diethylenetriamine and while attempting to prepare [AI(NMe2)2Clh via a reaction of lithium dimethylamide with aluminium trichloride. A new purifier material capable of removing trace moisture from hydrogen chloride has been prepared. The material, based on graphite-supported zirconium tetrachloride, is capable of removing trace moisture from a dynamic nitrogen atmosphere. Nitrogen containing moisture in the single figure ppm range was passed through the purifier whereby the moisture level was reduced to below 50 ppb. A review of graphite intercalation chemistry is included. Similar work with lanthanide chlorides is described. A new technique for the determination of the activity of commercial catalysts towards common trace impurities has been developed. The DSC technique has been used to assist Air Products in choosing an oxidation catalyst for the now commercially successful Built-in-Purifier [BIP]. The production of ultrapure water [UPW] for the semiconductor industry is reviewed; the common contaminants found in UPW, their effect on the production of integrated circuits, and methods used to remove these impurities are described. The potential of organobridged silicate xerogels as purifier materials is discussed and sol-gel chemistry reviewed. An organo-bridged silicate xerogel has been shown to remove trace P AH impurities from water.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available