Growth of ultra-thin SiO₂by laser-induced oxidation

Abstract

Pulsed laser-induced oxidation (LIO) has been suggested as an emerging technique to grow SiO 2 at room temperature. LIO of silicon in a mixture of oxygen and nitrogen under different proportions has been studied in detail. The effect of the partial pressure of oxygen and nitrogen gases on the quality as well as the thickness of the oxide grown has been studied. Also, the oxidation has been carried out in the presence of dc discharge inside the growth chamber and its effect on the oxide properties has been discussed. Higher values of ramped breakdown field strength, characteristic life-time and lower leakage current have been obtained for oxide grown in the presence of dc discharge. However, LIO without dc discharge offers a significant advantage in terms of the thickness of the oxide grown. The optimized LIO process has been used to grow ultra-thin (<1 nm) oxide on silicon with good control and the electrical characteristics of the resulting MIS structure have been studied in detail.

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“…Figure shows scanning electron microscope (SEM) micrographs of the cross‐section of locally laser‐oxidized samples. While the poly‐Si in the nonlasered region is removed during the KOH etching (see Figure B), the lasered regions are protected by a thin SiO 2 . The remaining poly‐Si is roughened and has a thickness between 90 and 190 nm, but nevertheless is still intact (see Figure C).…”