The defect is a main factor of affecting IC's yield and reliability.Defects can be divided into yield defects (hard faults)

reliability defects (soft faults) and goodness defects based on the difference between the defect's concept and fault's concept.The probability of a defect being a hard fault or a soft fault by the critical area of a defect is given and a more accurate yield model is gotten.A quantitative expression between IC's failure probability and functional yield is obtained by the relationship between the yield defects and reliability defects.IC's failure probability can be estimated by this quantitative expression using this IC manufacturing yield

and the research and development period can be shortened.