The use of computer aids in IC technology evolution

Abstract

Computer-aided analysis of integrated circuit devices has played a critical role for more than three decades of technology evolution. In the 1950s and early 1960s simulation was used extensively to characterize the operating principles of both bipolar and MOS devices. Bipolar effects such as base-width modulation and base pushout were characterized as well as MOS phenomena including gradual channel and channel-length modulation effects. During the late 1960s and throughout the 1970s simulation provided critical insight in the scaling of devices leading to the advent of very large scale integration (VLSI). Starting in the mid-1970s the modeling of fabrication technology became an important adjunct to device analysis. The need to control threshold and subthreshold behavior of scaled devices played a significant role in this synergistic coupling. Now in the mid-1980s the role of both device and process analysis have each come to new plateaus of both performance and utility. The scaling of submicrometer channel-length MOS devices poses a new set of constraints and challenges. This paper traces the evolution of computer-aided analysis over the past three decades. Unique aspects of the device physics and the role of device and process analysis at each phase of development will be presented. The progression from device conception towards stabilizing the technologies for large-scale product are presented. Problems of submicrometer technology including both production issues as well as new physical requirements for both process and device modeling will be dealt with, including the opportunity presented with the rapid advances in computer technology and the seemingly inevitable computational bottleneck posed by the growing needs for three-dimensional simulation.