OPTICAL RULE CHECKING FOR DETECTING AT RISK STRUCTURES FOR OVERLAY ISSUES

摘要

A method and system is provided for detecting at risk structures due to mask overlay that occur during lithography processes. The method can be implemented in a computer infrastructure having computer executable code tangibly embodied on a computer readable storage medium having programming instructions. The programming instructions are operable to obtain a simulation of a metal layer and a via, and determine a probability that an arbitrary point (x, y) on the metal layer is covered by the via by calculating a statistical coverage area metric followed by mathematical approximations of a summing function.

主权项

1. A method implemented in a computer infrastructure having computer executable code tangibly embodied on a computer readable storage medium having programming instructions operable to:
determine a probability that an arbitrary point (x, y) on a metal layer is covered by a via by calculating a statistical coverage area metric followed by a summing function; and detect at risk structures of a semiconductor device during lithography based on the determined probability, wherein determining the probability that the arbitrary point (x, y) on the metal layer is covered by the via comprises: determining that the metal layer is inside the via by calculating:Pin(viacovers[x,y])=1-P(Ox≤-x&Oy≤-y)=1-P(Ox≤-x)P(Oy≤-y)=1-14P(Ox≥x)P(Oy≥y)(equation1) wherein:
Pin is representative of a probability that the via covers the metal layer, at the arbitrary point; determining that the metal layer is outside the via by calculating:Pout(viacovers[x,y])=P(Ox≥(Rv-x)&Oy≥(Rv-y))=P(Ox≥(Rv-x))P(Oy≥(Rv-y))Equation(2) wherein:
Pout is representative of the probability that the via covers the metal layer, at the arbitrary point outside the nominal via shape; andOx and Oy follows Gaussian distributions to calculate for the Pin and Pout;Rv represents the radius of the nominal via shape, wherein the arbitrary point (x, y) is defined by an x coordinate and a y coordinate in a cartesian coordinate system, wherein P is a probability, and Ox and Oy is an overlay in an x direction and a y direction, respectively.