초록 ▼

The inventive "Substrate Effect Model" represents an improvement over the "Ebel Model," a conventional XPS-based methodology for determining carbonaceous overlayer thickness. The Ebel Model generally predicts a higher value than the measured value for the ratio of the carbon's C1s electron emission

The inventive "Substrate Effect Model" represents an improvement over the "Ebel Model," a conventional XPS-based methodology for determining carbonaceous overlayer thickness. The Ebel Model generally predicts a higher value than the measured value for the ratio of the carbon's C1s electron emission peak to the carbon's CKVV electron emission peak. The invention recognizes the existence and influence of the "Substrate Effect," whereby photoelectrons from the underlying substrate cause additional core-level ionizations in the carbon layer. The failure of the Ebel Model to account for the Substrate Effect is responsible for the variance between Ebel Model prediction and actual x-ray photoelectron spectroscopic measurement. In essence, the invention "corrects" the Ebel Model by accounting for the Substrate Effect. The inventive methodology is applicable not just to carbon but to a diversity of elements which may be found to be included by an overlayer which exists upon a substrate.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method for determining the thickness of an overlayer which is present on a substrate, said method comprising:effectuating x-ray photoelectron spectroscopy with respect to said overlayer, wherein said effectuating includes:measuring the intensity of an Auger electron e

[ What is claimed is:] [1.]1. A method for determining the thickness of an overlayer which is present on a substrate, said method comprising:effectuating x-ray photoelectron spectroscopy with respect to said overlayer, wherein said effectuating includes:measuring the intensity of an Auger electron emission peak with respect to an element in said overlayer; andmeasuring the intensity of a non-Auger electron emission peak with respect to said element; andevaluating the ratio of the measured intensity of said Auger electron emission peak to the measured intensity of said non-Auger electron emission peak, wherein said evaluating includes considering said Auger electron emission peak to be attributable to the combination of:direct x-ray excitation of said substrate; andx-ray excitation of photoelectrons from said substrate;wherein said evaluating includes solving for d in the equationZ represents said element;Z(A) is said Auger electron emission peak;Znl is said non-Auger electron emission peak;I.sub.Z(A) is the intensity of said Auger electron emission peak;I.sub.Znl is the intensity of said non-Auger electron emission peak;d is said thickness of said overlayer;.lambda..sub.Z (E.sub.Z(A)) is the inelastic mean free path of the Auger electrons in said element;.lambda..sub.Z (E.sub.Znl) is the inelastic mean free path of the nl photoelectrons in said element;.theta. is the angle of emission of photoelectrons with respect to the plane defined by said substrate;K is a constant which is equal to the measured I.sub.Znl /I.sub.Z(A) for an infinitely thick elemental sample;I.sub.Z(A).sup.x is a first portion of said intensity of said Auger electron emission peak, said first portion corresponding to direct x-ray excitation of said substrate;I.sub.Z(A).sup.e is a second portion of said intensity of said Auger electron emission peak, said second portion corresponding to photoelectron excitation from said substrate;[I.sub.Z(A).sup.e /I.sub.Z(A).sup.x ] equals [.pi.N.sub.s.sigma..sub.s.sup.i (h.nu.).lambda..sub.s (E.sub.s.sup.i).sigma..sub.Z(A) (E.sub.s.sup.i)] divided by [.sigma..sub.Z(A) (h.nu.)];N.sub.s is the number of atoms/cm.sup.3 in said substrate;.sigma..sub.s.sup.i (h.nu.) is the cross-section for photoelectron emission from the ith core level of said substrate;.lambda..sub.s (E.sub.s.sup.i) is the inelastic mean free path of substrate photoelectrons in said substrate;.sigma..sub.Z(A) (E.sub.s.sup.i) is the cross-section for Auger emission upon bombardment by electrons from the ith core level of said substrate; and.sigma..sub.Z(A) (h.nu.) is the cross-section for Auger emission by x-ray excitation.