US Patent 10930545 Method for forming semiconductor structure

A method for forming a semiconductor structure is disclosed. Among a stack of mask layers, any other layers above the lowermost thin film layer are subsequently removed to expose the lowermost thin film layer and then the lowermost thin film layer is separately removed by a dry etching process. This improves an etching uniformity of the lowermost thin film layer and ameliorates the issue of material residues. Moreover, thanks to the anisotropic characteristic of the dry etching process, lateral etching of side walls of a trench isolation structure can be mitigated.