Product Overlay Control and Analysis Package for Wafer Manufacturing
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Overlay is the displacement of the pattern of one semiconductor level with respect to another and is generally measured by reading verniers. Vernier scales are used on wafers during photolithographic operations to obtain precise alignment of patterns with respect to one another and to the wafer. Overlay data consisting of vernier values is recorded, tracked and analyzed for each level of the photolithographic process to assure conformance to overlay engineering specifications. This is an overlay data collection, control and analysis system using mostly software (BASIC language) for use with an IBM Personal Computer (PC) or compatible equipment. This package includes several features, as follows: (1) Data entry locations are moved easily since PCs are not connected to a host computer or other PCs.