US Patent 7579590 Method of measuring thin layers using SIMS

A method for measuring the thickness of a layer is provided, comprising (a) providing a structure (101) comprising a first layer disposed on a second layer; (b) impinging (103) the structure with a first ion beam comprising a first isotope, thereby sputtering off a portion of the first layer which contains a second isotope and exposing a portion of the second layer; and (c) determining (105) the thickness of the first layer by measuring the amount of the second isotope which is sputtered off.