Patent ID: 7973909
Filing Date: 2011-07-05
Classification: G03B,G03F

Abstract:
1. An extreme ultraviolet lithography (EUVL) system, comprising: a synchrotron which is used as a source of extreme ultraviolet radiation, wherein the source's energy decreases with time; a stepper which uses a step-and-repeat process to transfer patterns from a reticle onto a wafer, wherein the stepper uses the reticle to expose a region of the wafer, and after exposing the region, the stepper moves the wafer to a new location so that the stepper can expose another region on the wafer, and wherein each region of the wafer is desired to be exposed to a substantially constant dose; a computer, which includes a processor and a memory, wherein the memory stores instructions that when executed by the processor cause the computer to: wherein the EUVL system is calibrated to determine a proportionality constant k, wherein the substantially constant dose, D, the synchrotron current, I, and the stepper's exposure duration, T, are related by D=k·I·T.