On the dependencies of the stochastic patterning-failure cliffs in EUVL lithography

In this paper we will first review the metrology for detecting stochastic printing failures (or defects): which techniques are available and what is their performance in detecting the different failure types in regular L/S or contact arrays, in terms of sensitivity and wafer area they can cover. Although progress is being made, metrology is still a concern: not all types of failures can be detected with the sensitivity and area-inspection capability that will eventually be required for yield sign-off. Next, we look into the progress we have been making in generating empirical correlators (or predictors) that can reproduce observed dependencies of the position of the stochastic cliffs on patterning or structure parameters, such as focus-dose, illumination mode, mask bias and pitch. In this part we focus on the microbridge-cliff on resist wafers, with some initial data on the missing-contact cliff. Especially the pitch-dependency (proximity dependency) of the cliff position is a challenge, as good models for this dependency are crucial for the development of stochastic-hotspot predictors for the OPC Verification flow. In this paper we will present for the first time a reasonable predictor for this pitch dependency; but although these results a promising step forward, they are not yet good enough as a final solution. So, this type of research will need to be continued.