Micron and submicron patterns for semiconductor devices and integrated circuits

The fabrication of microwave planar transistors and very high speed integrated circuits is well known to depend on the realization of transistor or circuit patterns in the micron and submicron range. This paper discusses results of basic studies on the generation of such micro-patterns on photographic plates, and photosensitive resists as well as pattern etching in SiO2and metal films. The resolving power of various lenses on high resolution plates and photoresists has been measured as a function of the objective and illumination aperture. A resolution of 3000 lines per millimeter at an aperture close to 1 is obtained, demonstrating that the results are only diffraction limited. With a specially designed microscope objective, for example, a useful pattern of 1 micron linewidth, uniform over an image area of 80 × 80 mils, has been produced. For still larger image areas, a new lens has shown a resolving power of 375 lines per millimeter, uniform over an image area of 1 inch diameter. Presently, useful patterns of 3 microns minimum linewidth may be produced uniformly on 1 inch substrates, without using the step and repeat method in the final reduction step.