Manufacturing method of semiconductor structure

Abstract

A method includes forming a plurality of semiconductor nanostructures, and forming a hard mask comprising a top portion over the plurality of semiconductor nanostructures, inner portions between the plurality of semiconductor nanostructures, and sidewall portions on sidewalls of the plurality of semiconductor nanostructures. The method further includes etching the sidewall portions of the hard mask, with at least a top portion of the hard mask remaining, performing a first oxidation process to oxidize sidewall portions of the semiconductor nanostructures to form first oxide layers, removing the top portion and the inner portions of the hard mask, and performing a second oxidation process to oxidize top portions and the bottom portions of the semiconductor nanostructures to form second oxide layers. The second oxide layers comprise the first oxide layers. The second oxide layers encircle remaining portions of the plurality of semiconductor nanostructures.

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