This book describes means in improving the technology of LSI/VLSI ICs production. It does so by concentrating on improvements of manufacturing yield and quality of the products by detecting weak points which should be eliminated on the way up the learning curve. The book presents a systematic approach to the problem, covering primarily methods based on the use of test patterns measurements, in both mass production and in research and development activities. The main groups of defects found in IC chips and ways to detect them using test structures are discussed in detail.