Fly's-Eye Lens Technique for Generating Semiconductor Device Fabrication Masks

This Communication describes an improved method for fabricating multiple-image photographic masks of high quality. Photographic masks are commonly used in the fabrication of silicon transistors and diodes. Such masks are needed in sets of five, ten, or even twenty, each being used for one of the steps in the photoengraving-type fabrication process. Arrays of many devices are made at one time on a silicon wafer. The photographic masks are the corresponding arrays of microscopic images. Figure 1 shows a portion of two representative transistor masks. The center-to-center distance between the devices may typically be 0.020″, 0.025″ or 0.030″, with a total of perhaps 1000 devices in the array.