Chemical vapor deposition of Si on chlorosilane-treated SiO2 surfaces. II. Selective deposition in the regions defined by electron-beam irradiation

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Abstract
This article reports a selective-area deposition process using chlorosilane-treated ultrathin SiO 2 masks on which the patterns are directly defined by irradiation of a focused electron beam (EB). Three different chlorosilane gases ( SiH 2 Cl 2 , SiHCl 3 , and SiCl 4 ) were first adsorbed on the SiO 2 surfaces, and the regions with reactive sites were defined by taking advantage of electron-stimulated desorption(ESD) of the surface adsorbates. For the SiHCl 3 - and SiH 2 Cl 2 -treated surfaces, the nucleation density was remarkably high in the EB-irradiated regions. Such nucleation enhancement was less significant for the SiCl 4 -treated surface. For the purpose of direct patterning and selective growth, we conclude that SiHCl 3 is the optimum treatment gas because it effectively suppresses Si nucleation outside of the EB-irradiated patterns. The overall ESD sensitivity of the SiHCl 3 -adsorbed mask was 50 mC/cm2, and a significant nucleation enhancement was observed by irradiation of 7 mC/cm2. We also report an extension of this selective-area processing to window opening through the ultrathin SiO 2 mask layer. The factors limiting the minimum feature size of the grown Si structures and the opened windows are discussed.