Contact Window Metrology Using The Photocleave Technique

Application of the nondestructive Photocleave Technique for determining the shape and size of sub-micron contact windows defined in photoresist is described. Stepper-based printing in positive photoresist is assumed. Following conventional exposure of the contact windows in pass 1, the stepper is programmed to immediately execute pass 2, with an appropriate pass-shift, to expose a linear feature that sections the latent images of the contact windows. After development, a fast turn around SEM is used to determine the contact window parameters with an enhanced level of certainty as a result of using the Photocleave Technique.