STEPPER ALIGNMENT MARK FORMATION WITH DUAL FIELD OXIDE PROCESS

摘要

The present invention is a semiconductor photomask set for producing wafer alignment accuracy in a semiconductor fabrication process. Alignment marks are used to arrange various mask layers in nearly identical orientation with the underlying semiconductor mask pattern. Their chief function is to prevent mask misalignment. Traditional microchip fabrication methods result in the alignment marks being covered with layers of oxide material making accurate alignment a troublesome process. The photomask set (M1, M3) of the present invention produces an alignement mark (17M) that is accurate for subsequent fabrication after undergoing a dual field oxide fabrication process. The mask set (M1, M3) can be used in conjunction with stepper wafer alignment tools and is especially useful in forming semiconductor memory products capable of permorming block data erasure operations. The exposed alignment marker (17M) facilitates checking and testing mask misalignment during the fabrication process.