Step-and-repeat alignment and exposure method and apparatus

Abstract

An exposure apparatus usable in the manufacture of semiconductor devices, for transferring a pattern of a reticle onto each of discrete areas of a semiconductor wafer in a step-and-repeat manner. The apparatus has a laser interferometer for precisely measuring the amount of displacement of the wafer and a memory for storing positional errors of the shot areas, relative to respective target positions, established at the time of completion of the stepwise movements of the wafer. In accordance with the stored positional errors and with the result of measurement by the laser interferometer, the amount of stepwise movement of the wafer is corrected, whereby the accuracy of step-feed for the wafer is improved without decreasing the throughput. In another aspect, the exposure apparatus is provided with a TTL detection system for detecting the positional error of each of the shot areas relative to a target or reference shot area established at the time of completion of stepwise movement of the wafer. If a variation component of the positional error detected by way of the TTL detecting system is not less than a predetermined level, the positioning of the wafer is effected for each of the shot areas, by use of the TTL detecting system. If the variation component is less than the predetermined level, the positioning of the wafer or each shot area is effected on the basis of the measurement by the laser interferometer.