Patent ID: 6288769
Filing Date: 2001-09-11
Classification: G02B,G03F

Abstract:
An exposing method for irradiating a mask with an illuminating light and transferring a pattern on the mask onto a substrate through a projection optical system, said method comprising the steps of:supplying a gas having a lower capability of absorbing the illuminating light to each of plural chambers each being formed between plural optical elements disposed in a barrel;floating a contaminating substance attached to a surface of each of the plural optical elements in the gas by irradiating the plural optical elements with a light for removing the contaminating substance in a state in which the gas is supplied;exhausting the gas, in which the contaminating substance is floating in each of the chambers, from the barrel;supplying each of the plural chambers with further gas after exhausting the gas in which the contaminating substance is floating; andtransferring the pattern onto the substrate.