Patent ID: 7700444

Claim:
A tilted anisotropic plasma etching process comprising: a. A hard-mask layer with high etching selectivity to a substrate is put on top of the substrate, and first semi-dense features are printed with a standard lithographic process and etched into the hard-mask layer wherein the size of lines is three times of the size of spaces wherein the spaces have a first centerline; b. a resist is spun on the hard-mask layer and exposed again to print a second pattern of semi-dense features with its position shifted by a distance approximately equal to the space size such that the second features have a centerline that have a misalignment with the centerline of the first spaces underneath; c. the misalignment is measured right after the second lithographic step, based on which calculations of the needed tilting direction and etching angle to correct the misalignment; d. the calculations are used to determine the required shadow effect in an anisotropic plasma etching will be applied to correct the resultant misalignment wherein the etching direction is tilted and the due to the shadow effect, the tilted etching can produce dense structures in the first features with equal or nearly equal bottom width in the first semi-dense features.