1.4 Nanocmos device, circuit and system simulations

Co-authors:

Key concepts

• Use of 3D simulations to understand statistical fluctuations across devices
• Infrastructure to address security issues
• Results and progress in the management of device variability

Introduction

The increasing variability present in modern CMOS devices demands revolutionary changes in the design methodology, algorithms and tools used to produce integrated circuits and systems. Progressive scaling of CMOS transistors has driven the success of the global semiconductor industry, as captured by the reknowned Moore’s Law which stipulates an exponential increase of the number of transistors in chips, with some modern chips now comprising several billion transistors. Until recently the transistors in silicon chips were assumed to be of uniform design, having identical physical properties and characteristics. However as illustrated in Figure 1, as transistor dimensions approach the nanometer scale this assumption no longer holds true with microscopic differences in atomic structure, doping configuration and material granularity producing differences in the macroscopic behaviour of individual devices.

As a result Moore’s Law as tracked by the International Technology Roadmap for Semiconductors (ITRS) is now reaching the physical, atomistic limits of silicon and radical new approaches are needed that encompass this atomistic variability. To address this problem, it is now widely recognized that a paradigm shift must happen in circuit and system design. Strong links have to be established between system, circuit and fundamental device technology research in order to allow modern integrated circuits to cope with the statistically varying behaviour of individual transistors on a chip. Design methods must evolve to accommodate the increasing statistical variability of transistors and absorb the impact that this can have on circuit and system performance. The nanoCMOS project confronts these engineering challenges. This chapter introduces the project in detail and concludes with a brief look at future work in this area.

The nanocmos project: innovative engineering

Changing design rules for new device architectures and device variability adds significant complexity to the design process, requiring the orchestration of a broad spectrum of tools by geographically distributed teams of device experts, circuit and system designers. In the nanoCMOS project the challenges that this working method presents are being addressed by embedding e-Science technology and know-how in the device modeling and design groups and changing the ways in which these disparate groups currently work. The nanoCMOS project was funded for 4 years and started in October 2006. It involves collaboration between world leading device modelling and circuit and system design research groups at the universities of Glasgow, Edinburgh, Manchester, Southampton and York. This academic grouping is enhanced by strong links and collaboration with industrial partners including leading semiconductor, EDA tool vendors and design companies such as Freescale, Fujitsu, National Semiconductor, Synopsis, ARM, Wolfson Microelectronics amongst others. The project will provide valuable insights for industry on the challenges faced in the nanoCMOS domain and how the global semiconductor industry can address them.