Electron-Beam Programming and Testing of Complementary Metal-Oxide Semiconductor Systems

摘要

This paper describes the application of a scanning electron beam lithography system (SEBL) to the programming and testing of digital CMOS systems via the direct injection of charge into the integrated circuits. E-beam programmable interconnect structures, using floating-gate FETs,implement customization and fault avoidance techniques. E-beam controlled stimulus/response testing circuits, using substrate diodes, provide access to internal circuit nodes and thereby permit efficient testing procedures for large systems. Two system-level applications are presented-a digital multiplier and a crosspoint switch. In both cases, redundant circuit components and programmable interconnect are used to achieve fault tolerance and yield enhancement. An analysis of a wafer-scale crosspoint switch design indicates that e-beam restructuring techniques could be used to implement an 80x75 element array on a 4-in. wafer with 99% yield. The e-beam programming and testing circuits are shown to be compatible with commercial CMOS foundry services. The precision, speed, and automation of the SEBL system make these techniques practical for large-scale digital systems.