Postioning accuracy issues for 0.35 micron critical dimension microlithography

This paper addresses the effect of blank material topography on positioning accuracy due to design variance of the mask holders of any two pieces of equipment, and it highlights positioning accuracy issues seen on wafers resulting from mask holders and alignment methodology differences. If manufacturers primarily concern themselves with equipment-error budgeting, it is unlikely position accuracy goals can be attained. The mask and blank manufacturers must study different surface topography effects on all related tools. The writing tool and the stepper manufacturers must include the difference effects in their performance study. The metrology tool manufacturer must study not only the P/T (precision/tolerance) ratio to minimize the effects of the uncertainty of the measurement but also study the difference between the writing tool and stepper tool metrology. They must then define the best method and work with all the suppliers to carry it out.