Exposure wavelengths have shortened remarkably as device design rules have become increasingly minute. The switch over from KrF to ArF exposure and the development of techniques to use an even shorter wavelength of 157 nm have led to various problems related to the exposure process and changes in the resist materials. In this paper, we focus on 157-nm exposure, which will require thinner resist coatings and new resist materials to deal with the effects of light absorption and solvent transparency. We expect the structure and characteristic of future resist materials to be greatly improved compared to those of the current model. Despite the use of new resist materials, the need to lower the number of defects occurring during the lithography and finer design rules will make environmental control increasingly important as regards critical dimension control. Our knowledge of what environmental control will be needed is incomplete, though, and so we examine some of the environmental factors that will affect lithography with 157-nm exposure in this report.