METHOD AND APPARATUS FOR EXPOSING MULTI-LEVEL REGISTERED PATTERNS INTERCHANGEABLY BETWEEN STATIONS OF A MULTI-STATION ELECTRON-BEAM ARRAY LITHOGRAPHY (EBAL) SYSTEM

摘要

A B S T R A C TAn electron-beam array lithography (EBAL) system and method ofoperation is described, employing an electron beam column of the array opticstype having an array lens assembly, an array fine deflector assembly and acoarse deflector assembly for selectively directing an electron beam to adesired element of the array of lenslets and its associated element of thearray of fine deflectors, where one or more of the lenslets in the array may beflawed. The method and system further comprises deriving fiducial markingsignals from a lenslet stitching grid of fiducial elements, formed on a stan-dard stitching target, for calibrating the boundaries of the fields of view ofthe respective elements of the array of lenslets. The fiducial marking sig-nals are used to stitch together the individual fields of view of the elementsin the array of lenslets in order to cover a desired area of a workpiece sur-face to be subsequently exposed to the electron beam, for example, the surfaceof a semiconductor wafer upon which a plurality of integrated circuit chips areto be formed. In the event of flawed lenslets in the array lens, the locationsof those parts of the exposed area which were subject to the fields of view offlawed lenslets in the array lens assembly are mapped in a computer memory andthis information is used to blank the electron beam during any period that thecoarse deflector might be directing the beam to a flawed lenslet. The systemand method then physically permutes the position of the exposed target area toa net physical position subject to the field of view of a different array oflenslets. Appropriate coarse and fine deflection signals are then obtainedfrom the flawed lenslets, and the electron beam is then caused to retrace overthese areas in accordance with the master pattern specifications for this areaan the target surface whereby increased yield from the EBAL system is obtained.