Patent ID: 6996492
Filing Date: 2006-02-07
Classification: G01N

Abstract:
1. A method for determining an unknown parameter of a semiconductor specimen using a semiconductor inspection system, the method comprising: scanning a region of interest with an electron beam to cause X-rays to emanate from the region of interest; detecting the X-rays from the region of interest using at least one X-ray detector wherein the detected X-rays are within a certain energy range spectrum and thereby form an experimental X-ray spectrum; selecting a reference spectrum from an X-ray spectrum library based upon a set of inspection system parameters, a set of known semiconductor specimen parameters, and an initial estimated value for the unknown parameter; generating a simulated spectrum using a spectrum simulation algorithm based upon the set of inspection system parameters, the set of known semiconductor specimen parameters, and the initial estimated value for the unknown parameter, wherein the simulated spectrum is generated when an appropriate reference spectrum is not part of the X-ray spectrum library; comparing the experimental X-ray spectrum against either the reference spectrum or the simulated spectrum and determining the degree to which the experimental X-ray spectrum matches either the reference or simulated spectrum; when the experimental X-ray spectrum does not match the reference or simulated spectrum to a satisfactory degree, repeating the selecting, generating, and comparing operations wherein a new estimated value for the unknown parameter is used in place of the initial estimated value for the unknown parameter; and when the experimental X-ray spectrum does match the reference or simulated spectrum to a satisfactory degree, determining that the estimated value for the unknown parameter used to select the reference spectrum or to generate the simulated spectrum is approximately equal to the actual value of the unknown parameter.