Iii previous work by Sturtevant et al  it was shown how the use of scatterometry data obtained in real time during the post-expose bake (PEB) step of the photolithography process can improve critical dimension (CD) control. However, it is not obvious that the ad hoc methodology utilized during these experiments conducted at IBM, is the best way to use this valuable information. This paper focuses on the development of more rigorous methods that can incorporate scatterometry data in on-line prediction of the bake time necessary to achieve the target CD. First, a brief description of the system and required tools is given. Then, a model that can relate the measured intensity and the time the wafer has been baked (referred to hereafter as the bake time) is introduced. Then, two theoretical methods that can utilize this model to calculate the bake end point are described. Finally, these two methods are applied to the analysis ofadditional data collected at IBM and operation oftbe complete end point control system is emulated to the extent that is possible.
Keywords: end-point detection, process control, deep-UV lithography, scatterometry, post-exposure bake process