System and method using in situ scatterometry to detect photoresist pattern integrity during the photolithography process

Abstract

The present invention uses in situ scatterometry to determine if a defect (e.g., photoresist erosion, photoresist bending and pattern collapse) is present on a wafer. In one embodiment, in situ scatterometry is used to detect a pattern integrity defect associated with the layer of photoresist. In situ scatterometry produces diffraction data associated with the thickness of the photoresist patterned mask. This data is compared to a model of diffraction data associated with a suitable photoresist thickness. If the measured diffraction data is within an acceptable range, the next step of the photolithography process is carried out. However, if the measured thickness is outside of the suitable range, a defect is detected, and the wafer may be sent for re-working or re-patterned prior to main etch, thereby preventing unnecessary wafer scrap. Another aspect of the present invention allows for a feedback control mechanism to alter a physical parameter of the photolithographic process based upon the in situ scatterometry measurements.