In semiconductor manufacturing, run-to-run (RtR) control is paid moreand more attention. In this paper a set-valuedRtR control scheme is introduced. Different from conventional RtR controlmethods, the set-valued method first calculates the feasibleparameter set at the beginning of each run, then estimates the modelparameters within this set. Compared to other RtR control schemes, itdoes not assume any statistical property of the noises. In simulation itwas shown that it is robust tomodel and sensor errors, and it has the potential to be applied tohighly nonlinear processes. Furthermore the set-valued method can beapplied to other fields such as signal processing and chemical processes.