Shallow angle cut along a longitudinal direction of a feature in a semiconductor wafer

Abstract

A cut of a longitudinal feature (such as a trench in a semiconductor wafer), is made not perpendicular to or parallel to the feature, but instead at an angle to the longitudinal direction of the feature. Specifically, if the longitudinal feature is oriented along an X axis, then several embodiments cut the feature along a shallow angle θ relative to the X axis, to form a cross-section of the feature that is substantially elongated. The amount of elongation of the cross-section depends on the shallowness of angle θ. Specifically, the shallower the angle θ, the more elongated the cross-section. Such an elongated cross-section is evaluated by a tool whose resolution limit has been reached and which tool cannot be used to evaluate a normal cross-section of the feature. Therefore resolution-limited tools have an extended life by use of shallow angle cuts as device geometries shrink below their resolution limits.

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