Diebold A.C. (Ed.) Handbook of Silicon Semiconductor Metrology

Marcel Dekker, 2001. — 890 p. — ISBN: 0-8247-0506-8.The Handbook of Silicon Semiconductor Metrology is designed to serve as a reference to both the metrology and processing communities. The volume is intended for a broad audience, from research to development and manufacturing. Whenever possible, chapter authors have provided a description of the science of the measurement along with applications to the most recent materials and processes. Another appropriate title for this book would be The Science and Technology of Silicon IC Metrology. The more one knows about the science behind measurement technology, the better one is able to ensure that a given metrology method will provide useful and correct information. It can serve as an advanced reference and text for those studying the processes used in silicon integrated circuit (IC) manufacturing.
Metrology itself is a wide-ranging field. An overview is provided in the introductory chapter. Trends in the logistics of measurement technology such as integrated metrology are also covered in the introduction. The introduction conveys the following philosophy: Measurement data becomes a value for a physical parameter such as thickness only after a model is applied to the data and to the measurement instrument.
Most of us think of metrology as measurement and its connection to process control. As the silicon wafer proceeds through the fabrication facility (FAB), metrology is used to ensure that the wafer has features that fall within a range of parameters that will result in ICs that have a specified set of electrical properties such as clock speed. When one looks at a generic process flow, the three most used measurements are overlay, critical dimension measurement, and defect detection. Equally critical measurements are done to ensure implant dose, the thickness of the gate dielectric, and thickness of the barrier layer for interconnect metal lines, among others. Whenever possible, the latest methods for measuring these properties have been included.
It is interesting to note that the industry has long emphasized precision over accuracy. This has changed, and an international viewpoint is one that emphasizes both aspects of a measurement. The increased need for accuracy can be traced to the shrinking of device size and the trend toward transfer of processes from process tool supplier to IC manufacturer. Integrated circuit manufacturers have traditionally found insightful ways to transfer processes from development to manufacture, including the use of golden wafers. The contributors to this book were asked to discuss measurement calibration and precision. Several chapters discuss calibration methods, including one chapter that is specific to the calibration of defect and particle sizes.
Measurement data becomes useful when it is turned into information. This topic is covered in chapters that describe data management for all measurements and the use of electrical test structures for statistical metrology. Another chapter on manufacturing sensitivity describes how the variation of the physical parameters, which metrology tools typically measure, is related to the variation of electrical properties of transistors.
The final part of this volume contains chapters describing reference measurements and the physics of optical measurements. In addition, the new area of ultraviolet (UV) ellipsometry is covered. This section should prove very useful to those seeking to calibrate their metrology tools, especially when reference materials are not available.