Fogging effect compensation technique for photomask making

We investigated a new method for decrease of CD disparity due to fogging effect at photomask making, utilizing side- wall-angle-dependence of CD loss through descum process. We demonstrated this method could be valid for less than half- micron. This method can be effective on condition of anisotropic descum, no 'foot' at post-descum, and just- or under-development. Using this method, we obtained CD uniformity of 18.6 over fogging and non-fogging field, including process error.