Haze Defect And Litho Yield Improvement

Higher precision, more efficiency, larger the wafer size, and more narrow the line width are the most critical factors that the semiconductor industry is continuing pursued. To reduce haze defect becomes one of the most challenge to improve the production yield because the haze defect is more and more serious while the lithography technology coming into 193nm generation. This research, combining the haze defect theory with the analysis of those real data from fab based on the concern of cost, efficiency and effectiveness, provides semiconductor industry a practicable solution to reduce haze defect.From the principle haze defect, it is the integrated product of acid-base reaction which mainly from sulfate, ammonia and other substances in a particular environment. The haze defect has a closely relative with the wafer size, lithography wavelength, lithography process parameters, the mask environment and mask own manufacturing and cleaning processes. It is the semiconductor development for the wafer size magnification, lithography wavelength shorten, mask pattern denseness. And the haze defect solution will be focused on the improvement both for the mask environment and the mask own process.The mask environment could be divided into mask the work environment and storage environments. The gas filter will be installed on the specific location for the entire plant, tool and mask room etc. It is significantly improvement for the mask working environment, but to the limit effect for the haze defect improvement. And overall cost is high. It is the combination of the mask placed box, mask cabinets and mask stocker for the mask storage environment improvement. After modification for the mask placed box, mask cabinets and mask stock, this method will provide and keep the continuous extra cleaning gas to the mask. It will reduce the impact for the external environment. The mask storage environment has reached a large improvement from the test data. It is a large improvement for the haze defect. The cost is lower than previous solution.The traditional mask manufacturing and cleaning process both includes sulfur. It will gradually out of dialysis during the latter part of the use and storage. It is an one of the major source of the haze defect. The nonsulphide mask manufacturing and cleaning process is the important direction of development. It has made some improvement at present. But the relative process still not be perfect.It is a good method to combined with the mask inspection and wafer pattern confirmation. It might not only found early haze defect to reduce the yield impact, but also could effectively reduce costs.