Sensor Technology and Devices

This book deals with a subject that is highly important and has many technological implications and industrial applications. The material offers an insight into different aspects of the manufacturing and characterization of (almost exclusively) silicon sensors, devices that, without doubt, are the most widely used in the sensor arena, although other emerging materials and compounds are being increasingly employed. In spite of having been published in 1994, and considering the fast evolution of microelectronics, the book is a suitable reference for all those interested in silicon microsensors, complementing in some aspects the extensive literature on the topic. The book is by a group of authors with much experience, not only in academic areas but also in the manufacturing and application of sensing devices. People working in industry, research and universities contribute to the book, covering the subject from different points of view. The contribution of professionals from an important semiconductor company is remarkable, giving many details about the technology involved in the fabrication of the devices. Although the manufacturing procedures are similar to the well-known ones used in microelectronics, there are substantial differences, depending on the application, which are well explained throughout the book. The authors succeed in their attempt to help the reader to understand the basic methodology employed to manufacture the most popular silicon sensors, which is an important feature for professionals interested in acquiring knowledge of the performance limits of the sensors and their relationships with the fabrication processes. At the same time, these chapters constitute a good starting point for people who are preparing for their future work in the field. The first half of the book introduces the technological aspects of the manufacturing of silicon sensors, beginning with the basis of modelling, following with the different methods of fabrication (bulk/surface micromachining, wafer bonding) and ending with a description of packaging technologies (an important issue in the application area). These chapters can be considered as the core of the book and are written clearly, introducing the inexpert reader to the fascinating world of silicon microsensor technology. The remainder of the book deals with several kinds of sensors used widely in industry: magnetotransistors, thermal sensors, photosensors, CCDs and mechanical sensors (accelerometers, pressure and others), while the final chapter explains an electronic technique based on oscillators suitable for reading the information from some sensors (resistive and capacitive). The reader will not find a complete description of the usage methodologies, but only a brief introduction with details about some configurations familiar to the authors. For instance, pressure and acceleration sensors are mentioned in several chapters (even duplicating part of the material) while other important sensors (chemical, humidity, ultrasonic) are omitted, perhaps partly justified considering the space limitations of a single book. In summary, this book constitutes a good introduction for those interested in silicon microsensors, who will find many details concerning the technological aspects of their manufacture. On the other hand, the book fails to give a clear picture of the practical applicability of the sensors discussed and the associated electronics is restricted to the oscillator. Its easy style and the great number of references make it a suitable textbook for a graduate course in silicon microsensors. P Olmos