Interaction and balance of mask write time and design RET strategies

Abstract

It has been demonstrated that the write time for 50keV E-beam masks is a function of layout complexity including figure count, vertex count and total line edge. This study is aimed to improve model fitting by utilizing all the variables generated from CATS. A better correlation of R 2 = 0.99 was achieved by including quadratic and interaction terms. The vertex model was then applied to estimate write time of various nano-imprint templates. Accuracy of the vertex model is much better than the numbers generated from E-beam tool software. A 90nm test layout was treated with a mask optimization (MO) algorithm. A 26% write time reduction was observed through shot count reduction. The advanced features of the new generation E-beam writing tool combined with mask layout optimization, allows the same level of mask cost even though the capital cost of the new tool set increased 25%.