Towards a Theory of VLSI Layout

Abstract

As the complexity of digital systems grew, the need arose for efficient packaging of the system components. Starting in the mid 50’s, individual devices were placed on printed-circuit boards. As the size and the complexity of the modules grew — from individual devices to integrated circuits — the princed-circuit board has preserved to this day its function as a fundamental packaging level in the assembly of digital systems. However, a new layout horizon emerged, represented by the internal structure of the modules themselves (chip complexity). Today, the latter is the predominant problem in system layout: however, in spite of largely different feature sizes, the two environments — VLSI chip and printed-circuit board — are both governed by analogous sets of rules for the layout of wires on a regular grid. The highly structured layout medium and the necessity to cope with problems of increasing size motivated the development of automatic techniques and stimulated the attending research.