Method for manufacturing metal oxide semiconductor transistor in semiconductor substrate, involves removing additional upper portion of silicon oxide layer and upper portion of silicon nitride layer by etching plasma offset

摘要

The method involves forming a provisional grate (5) of polycrystalline silicon on a surface of a substrate (1). The provisional grate and the substrate are coated by a stack of a silicon nitride layer (13) and a silicon oxide layer (15). Top of the stack is flattened by removing an upper portion of the silicon oxide layer by chemical mechanical polishing. An additional upper portion of the silicon oxide layer and an upper portion of the silicon nitride layer are removed by etching plasma offset, where the etching is terminated when an upper face of the grate is formed.