| CPC H01L 21/823412 (2013.01) [H01L 21/30604 (2013.01); H01L 21/823437 (2013.01); H01L 21/823481 (2013.01); H01L 29/0665 (2013.01); H01L 29/42392 (2013.01)] | 20 Claims |

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1. A manufacturing method of a semiconductor device, comprising:
forming a stack of first semiconductor layers and second semiconductor layers alternatively formed on top of one another, wherein a topmost layer of the stack is one of the second semiconductor layers;
forming a patterned mask layer on the topmost layer of the stack;
forming a trench in the stack based on the patterned mask layer to form a fin structure;
forming a cladding layer extending along sidewalls of the fin structure; and
removing the patterned mask layer and a portion of the cladding layer by performing a two-step etching process, wherein the portion of the cladding layer is removed to form cladding spacers having a concave top surface with a recess depth increasing from the sidewalls of the fin structure.
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