Patent ID: 6825938
Filing Date: 2004-11-30
Classification: G01B

Abstract:
A film thickness measuring method comprising:preparing a wafer with a film to be measured, which is made in such a manner that a multilayer metal wiring structure is formed on a base wafer, said multilayer metal wiring structure including a metal wiring and an interlayer insulating film, and said film to be measured is formed on said multilayer metal wiring structure; preparing a reference sample of the same wafer as said wafer including said multilayer metal wiring structure formed on said base wafer and without said film to be measured; projecting white light onto said wafer with said film to be measured and sensing a first reflected light intensity from said wafer for each wavelength; determining a value of said sensed first reflected light intensity for each wavelength in a form of a first light intensity profile with wavelength as an abscissa axis and light intensity as an ordinate axis; projecting said white light onto said reference sample and sensing a second reflected light intensity from said reference sample for each wavelength; determining a value of said second reflected light intensity for each wavelength in a form of a second light intensity profile with wavelength as the abscissa axis and light intensity as the ordinate axis; calculating a normalized light intensity profile by dividing said first light intensity profile by said second light intensity profile; and calculating a film thickness of said film to be measured from said normalized light intensity profile, wherein, by regarding said reference sample including said multilayer metal wiring structure as a single substrate, a theoretical light intensity profile for said single substrate is calculated using a theoretical film thickness as a parameter, and by comparing said theoretical light intensity profile with said normalized light intensity profile, a theoretical film thickness at which a difference between said theoretical light intensity profile and said normalized light intensity profile becomes smallest is identified as said film thickness of said film to be measured.