Patent ID: 6215896
Filing Date: 2001-04-10
Classification: G03F,H01L

Abstract:
A system for enabling the real-time detection of a focus-related defect induced in a semiconductor wafer during a photolithographic process, said wafer including a plurality of cells, the system comprising:a photolithography stepper for transferring an image to each cell of said wafer, said photolithography stepper outputting focus data, including z-height data, for each cell;a fault detection module electrically connected to said photolithography stepper for receiving the focus data output for each cell and, in response to said focus data for all the cells of said wafer, for calculating a mean and standard deviation directly from the focus data for all of the cells on the wafer and comparing the calculated standard deviation to the mean .+-.3.sigma., representative of a completely flat wafer having no hotspots or other focus abnormalities thereon; andwherein in response to a determination that the calculated standard deviation does not fall within said mean .+-.3.sigma., said fault detection module halts operations of said photolithography stepper.