Optical MTF evaluation for the photolitographic technology

Measurements of the modulation transfer function (MTF) for different photolithographic exposure tools, such as contact, proximity, and projection printers have been made by the Fourier analysis of an exposed and developed positive photoresist profile. Through the obtained MTF data, the optical performance of the tools is presented concerning linewidth accuracy, reduction in developed photoresist thickness, and linewidth variations at steps. The general conclusion is that hard contact printers are superior to commercially available projection printers at present in the trend toward smaller pattern geometries.