METHOD AND APPARATUS FOR REGULATING REFRACTIVE INDEX VARIATIONS OF A LITHOGRAPHIC TOOL

摘要

The present invention provides a method and system for controlling the refractive index of a gas mixture of the projection optical system of the lithography tool. In one embodiment, the present invention is the projection optical system to correct the aberration due to the highly non-atmospheric pressure fluctuations. Furthermore, the present invention provides the ability to discharge the gas from the optical system and the ability to compensate for the capacity, the pressure fluctuation for compensating for the aberration over the control, height variation of the optical system. In an embodiment, at least one gas supply for providing gas for the system is a mixture of the invention, being associated with each of the gas supply, a mixture measuring and controlling the amount of each gas to at least one of and a mass flow controller and the at least one flow meter or a filter device for maintaining a laminar flow in a lithographic apparatus. According to another embodiment of the invention, the system is adding at least one temperature control device for maintaining the at least one temperature of the filter with the mixture for purifying of the gases of each of the gas supply to a predetermined thermal specifications It includes a. ; The refractive index changing apparatus, lithography tools, mass flow controller, a projection optical system, aberrations