Pushing ArF Dry Scanner Beyond Limitation

ArF dry scanner contact hole printing capability was successfully driven down from 120nm to 100nm, exceeding Acceptance Test specification (ATP) contact printing capability. The improved 100nm printing capability showed good process margin, Critical Dimension (CD) uniformity and wafer-to-wafer repeatability. Phase Shifting Mask (PSM) showed better performance than binary mark. Larger mask bias demonstrated better printability. PSM with 40nm mask bias resulted in most rounded hole profiles with no formation of side-lobe. Conventional illumination with high partial coherence factor produced the least iso-dense bias. usable Depth of Focus (uDOF), Exposure Latitude (EL), CD Uniformity (CDU) and Wafer-to-Wafer (WTW) repeatability were quantified and established.