Patent ID: 6466308
Filing Date: 2002-10-15
Classification: G01L,G01N

Abstract:
A method for measuring a thermal expansion coefficient of a thin film deposited on a substrate by phase shifting interferometry comprising the following steps:a) measuring a phase function of a target surface of a first substrate at a first measuring temperature; b) depositing a thin film on said target surface of said first substrate; c) measuring a phase function of said thin film by using the same conditions as those in step a); d) calculating one or more relative heights of one or more points with respect to a central point of said substrate prior to and after the deposition in step b) by using the phase functions obtained in steps a) and c, respectively, and calculating a difference of the relative heights at a savie point prior to and after the deposition in step b) for each of said one or more points; e) calculating a stress of said thin film for each of said one or more points by using said difference from step d) and calculating an average stress of said thin film therefrom; f) obtaining another on or more average stresses of said thin film of another one or more measuring temperatures by repeating steps a), c), d) and e) except that said first measuring temperature is replaced by said another one or more temperatures, and obtaining a first set of data of said average stresses versus said measuring temperatures with respect to said first substrate; g) measuring a phase function of a target surface of a second substrate at a second measuring temperature, wherein the second substrate has a thermal expansion coefficient different from that of said first substrate; h) depositing a thin film on said target surface of said second substrate with the conditions same as those in step b); i) measuring a phase function of said thin film in step h) by using the same conditions as those in step g); j) calculating one or more relative heights of one or more points with respect to a central point of said substrate prior to and after the deposition in step h) by using the phase functions obtained in steps g) and i), respectively, and calculating a difference of the relative heights at a same point prior to and after the deposition in step h) for each of said one or more points; k) calculating a stress of said thin film of step h) for each of said one or more points by using said difference from step j) and calculating an average stress of said thin film of step h) therefrom; l) obtaining another one or more average stresses of said thin film of step h) of another one or more measuring temperatures by repeating steps g), i), j) and k) except that said second measuring temperature is replaced by said another one or more temperatures, and obtaining a second set of data of said average stresses versus said measuring temperatures with respect to said second substrate; and m) calculating a thermal expansion coefficient, &agr;f, of said thin film by using said first set data and said second set data.