Method and apparatus for precision determination of phase-shift in a phase-shifted reticle

摘要

An attenuating phase metrology cell on a reticle comprising an attenuating feature and a binary feature. The metrology cell is used to determine amount of focal shift associated with the attenuating phase-shifting material. A dimension of an image of the attenuating feature is measured at a number of focal distances from the reticle. Thereafter a first relationship between the measurements of the attenuating feature and the focal distance is determined. A dimension of an aerial image of the binary feature is also measured at a number of focal distances from the reticle. The relationship between the measurements of the binary feature and focal distance is determined. An amount of focal shift is then determined based upon the first and second relationships. The attenuating metrology pattern can thus be included on an attenuating phase-shifting reticle, such that the focal shift of the attenuating phase-shifting reticle can be determined.