SUBSTRATE PROCESSING METHOD FOR FORMING INNER SPACERS IN A NANO-SHEET DEVICE

A method including depositing a dielectric film on a substrate including stacked structures with recessed portions formed on side surfaces of each of the stacked structures, wherein the dielectric film is deposited so that the stacked structures are covered at a thickness which is equal to or less than half a width of the recessed portions; filling a trench or trenches that are located between the stacked structures with a sacrificial film; etching the sacrificial film along the stacked structures; etching the dielectric film so that the dielectric film is etched more than the sacrificial film; removing the sacrificial film; after the removing of the sacrificial film, depositing a dielectric film to a thickness equal to or less than half the width of the recessed portions; and etching the deposited dielectric film, on a condition that the deposited dielectric film remains in the recessed portions.