Patent ID: 6350626
Filing Date: 2002-02-26
Classification: G01R

Abstract:
A method of testing EM lifetime used for estimating the EM lifetime of a metal at an used temperature (Tuse), wherein the metal has a critical line-width (WC), a critical temperature (TC), a lattice diffusion activation energy (QL) and a grain boundary diffusion activation (QGB), which method comprises:performing an isothermal EM test step at a test temperature (Ttest) to obtain a first EM lifetime (ttest), wherein the test temperature (Ttest) is higher than the critical temperature (TC); and substituting the used temperature (Tuse), the lattice diffusion activation energy (QL), the test temperature (Ttest) and the first EM lifetime (ttest) into equation (1a) to obtain a real EM lifetime (tuse) if the metal has a real line width (W) larger than the critical line width (WC) and the used temperature (Tuse) is higher than the critical temperature (TC); substituting the critical temperature (TC), the lattice diffusion activation energy (QL), the test temperature (Ttest), the grain boundary diffusion activation energy (QGB), the used temperature (Tuse) and the first EM lifetime (ttest) into equation (1c) to obtain a real EM lifetime (tuse) if the metal has a real line width (W) larger than the critical line width (WC) and a used temperature (Tuse) lower than the critical temperature (TC); substituting the critical temperature (TC), the lattice diffusion activation energy (QL), the test temperature (Ttest), the used temperature (Tuse) and the first EM lifetime (ttest) into equation (2) to obtain a real EM lifetime (tuse) if the metal has a real line width (W) smaller than the critical line width (WC); wherein equations (1a),(1c) and (2) are shown as follows: t50&it;use=ttest&af;(jusejtest)-n&it;exp&af;(QLk&it;(1Tuse-1Ttest))&it;&NewLine;&it;for&it;â€ƒ&it;T>TC&it;â€ƒ&it;and&it;â€ƒ&it;W>WC;(1a)t50&it;use=ttest&af;(jusejtest)-n&it;exp&af;(QGBk&it;(1Tuse-1TC)-QLk&it;(1TC-1Ttest))&it;&NewLine;&it;for&it;â€ƒ&it;T<TC&it;â€ƒ&it;and&it;â€ƒ&it;W>WC;(1c)t50&it;use=ttest&af;(jusejtest)-n&it;exp&af;(QLk&it;(1Tuse-1Ttest))&it;&NewLine;&it;for&it;â€ƒ&it;W&leq;WC;(2)wherein j is a current density, n is a constant.