The theme of this research is an investigation into the problems of laying out three-dimensional integrated circuits and the potential benefits of such layouts. The effects of varying different physical parameters on the total signal length of a wide selection of circuit types are investigated, and the results are reported in depth. The circuits investigated include the Cambridge Fast Ring. The general conclusion of the research is that the proposed layout techniques will be suitable when the problems of poor yield of multilayer fabrication can be solved. Problems of cooling are also briefly discussed. Designers with an interest in this field should read at least the conclusion (chapter 9), which clearly and succinctly presents some interesting results. For the immediate future we cannot expect more than two active layers, but developers of future automated layout CAD systems are given signposts to methods of three-dimensional layout with many active layers.
This book originated as a doctoral dissertation. Its purposes, which it achieves well, are threefold: to give greater visibility to research work being carried out in the United Kingdom; to provide a model for other doctoral students in computer science; and to serve as a textbook for designers and hardware engineers.
The details of the experiments are reported clearly, and the results and conclusions are easily available in chapters 7 and 8. These chapters will be a good reference for designers and hardware engineers involved in the development of practical three-dimensional integrated circuits. Methods of routing using special cells within the active layers, as well as using interconnect layers between the active layers, are discussed.
The early introductory chapters are perhaps less relevant to the practicing engineer. As an introduction to VLSI techniques, however, they are generally good except for a few minor omissions. They also set the scene for the later chapters, in particular with good descriptions of modern technologies. Three-dimensional tessellations are described from basic principles, without reference to the extensive literature in this field.
The nine pages of references are suitable for a doctoral thesis and will be useful for workers in the field. One interesting aspect of this book is that the work was selected as a distinguished dissertation in computer science. It is a report on the engineering of the hardware of VLSI, a topic that some people might argue lies outside the realm of computer science. In a sense, therefore, it may help to define, at least in the U.K., the breadth of topics that should be considered part of computer science.
The book is well structured and will serve as an excellent example of good, succinct writing for future doctoral students, as well as demonstrating the author’s depth of study of the subject. More than that, it gives visibility to British research and is a good book for designers and hardware engineers who want answers to many questions relating to three-dimensional circuit layout. The designers of future CAD layout systems will use the results of this work.