An optical lithography exposure apparatus which may be a stepper or a scanner, provides a wafer chuck that retains a wafer and at least one opaque exposure shield that extends over a discrete peripheral edge portion of the wafer thereby preventing illumination from exposing the portion of the wafer beneath the exposure shield. In a positive photoresist system, the portions of the wafer blocked from exposure by the shields, include alignment marks and the unexposed photoresist remains over the alignment marks thereby protecting the alignment marks from destruction or damage during subsequent patterning operations used to form patterns in the film being patterned.