Projecting Wafer Probe Yields for Products Fabricated in New Technologies

摘要

It is desirable to be able to forecast wafer probe yields for new products to be fabricated using the next generation technology. This is advantageous to assess the cost effectiveness of developing new technologies as well as to be able to plan wafer starts for these products. This paper will illustrate two methods for calculating yields for these new products. The first is a relatively simple method using the relative feature sizes of the new technology compared to the previous generation. This will give a good estimate assuming overall defect densities and defect size distributions are known for the previous technology. The second method is more detailed and accurate and also requires more detailed information regarding defect densities at various critical layers of the process. This method utilizes critical area analysis (CAA) and therefore cannot be performed until the actual product layout is complete. Also, the method for assessing the return on investment of developing the new technology will be explained. It will be shown that, for typical defect density size distributions, it is definitely cost effective and profitable to develop next generation technologies.