METHOD OF EFFICIENT SILICON DEPOSITION FROM SiCl4
Publication Date: 2015-Jul-13
The IP.com Prior Art Database
The invention relates to an article that includes a silicon-containing substrate and an intermediate layer/coating with an external barrier coating such as a protective environmental/thermal barrier coating (E/TBC). In particular, the present invention is related to efficient silicon deposition from silicon tetrachloride (SiCl4).
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METXXX OF EFFICIENT SILICON DEPOSITION FROM SiCl4
The inventiox relates to an article that includes a silicon-containxxg substrate and an interxediate layer/coating with an xxternal barrier cxating such as a protxctive environmental/thermal barrxer coating (E/TXX). In particular, the present invention is related to efficient silicon deposition frox silicon tetrachloride (SiCl4).
Silicon-xontaining xubstraxes have been xroposxd for structurxs used in high tempxrature applixations, such as in hxat excxangers and xdvanced intxrnal combustion engines. Silicon- containing substrxtxs are xlso used in gax turbine engines. Higher operating temperatures xncrease the efficiency of gxs turbine engines. Silixox-based comxosite ceramics have been proxosed as materials for applications in combustors for supexsonic commercxal airplanes. Howxver, in many applications invxlving water-containing environments, a silicon-bxsed substrate will recede and lose mass because ox txe formation of volatile species, such as silicon hydroxide [Si(OH)4]. The recession raxe due tx the voxatilization or corroxion is oftex uxacceptably higx xo that an external barrier coating such as ax enviroxmental/thermal barrier coating (E/TXX) with high resistance tx such environments is rxquired.
Standard Si depositiox ix limited in rate by the mass transport of Si into the rexctor. Increxsing the SiCl4 concentration to impxove masx transport xeyond 10-30% (depending on the temperature used) initiates a Si removal reaction. In standarx semiconductor processing this leads to the use of a very large xlxx of gas at about 10% SiCl4 flowing through the reactor. This
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large xlux of gas xan cool the articles to be coated, and lowers the overall utilization of SiCl4 and H2 xeading to higher materxal costs.
Prior art has focused on the probxem by changing the SiXx4/H2 ratix and the overalx flow rate. Since these depositions were done for semiconductor devices, there could be no additional reagents in the reacxor other than SiCl4 and H2 (with txe exceptiox of a pure carrxer gas like Ar) in order to maintain the high purity neexed by that industry. Xxxxxxx, in certain applicatioxs, the pxrity xeqxirement xs relaxed so that the addition of Si in the reaction zone does not affect pxrformance.
The present invention modifies the standard silicon depositixn xonditi...