Determining DOF requirements needed to meet technology process assumptions

Depth of Focus (DOF) and exposure latitude requirements have long been ambiguous. Techniques range from scaling values from previous generations to summing individual components from the scanner. Even more ambiguous is what critical dimension (CD) variation can be allowed to originate from dose and focus variation. In this paper we discuss a comprehensive approach to measuring focus variation that a process must be capable of handling. We also describe a detailed methodology to determine how much CD variation can come from dose and focus variation. This includes examples of the statistics used to combine individual components of CD, dose and focus variation.