A proposal for the contact hole assist feature printing checker in IML

Interference Mapping Lithography (IML) is the latest innovation to extend optical imaging solutions to contact hole printing. This approach optimizes the placement of assist features to enhance the process window of the contact hole layer. However, the printing of assist features is a concern of the IML technology. This study presents a checking scheme to analyze the assist feature printing using the aerial image simulation. If the checking method confirms the assist feature printing, the adjustment algorithm optimizes the assist feature design. An example of a 5x5 array pattern is employed to demonstrate the methodologies; which avoid assist feature printing yet still improve the process window by adding the appropriate assist feature design.