Etch proximity correction for dense array patterns

As critical dimension (CD) shrinks, the spec of CD uniformity (CDU) is getting tighter. To ensure CDU requirement, OPC team is making great efforts on etch proximity correction (EPC) than ever. For a long time, EPC only considers aperture effect which is usually simplified as a width and space rule table. However, astechnical nodes ever-shrinking, microloading effect plays a much more import role than aperture effect and rule table is not suitable any more. As in microloading effect pattern density is the key factor, we studied the density effect on dense array patterns with fixed CD and pitch in this paper. Firstly we designed a series of test pattern for calibrating an etch model, then we refined a simplified density rule table from the good fit (R2 >0.94) etch model. Contrast to traditional width/space rule table and complicated etch model, this approach is convenient and effective on dense array patterns EPC.