Fabrication of a miniature 8K-bit memory chip using electron-beam exposure

Abstract

A fully-ion-implanted miniature 8192-bit random-access memory chip has been fabricated using electron-beam lithography with minimum linewidth between 1 and 1.5 μm and advanced Si FET technology. Device structure, processing steps, mask transfer, and reactive ion etching processes capable of fabricating device structures in the micrometer and submicrometer dimensions are described. With a minimum linewidth of 1.25 μm, the memory chip occupies an area of 1.1×1.6 mm with an array density of 5 million bits/in.2 (0.8 million bits/cm2). A typical readout access time of 90 ns was measured on a functional chip.