The Rational Photomask Layout Design of Vias for Application in Double Patterning UV Photolithography

Due to the optical diffraction limit, the resolution of conventional UV photolithography is around ~1 micron, which hinders its potential in sub-micron patterning for broader applications. Efforts have been made to overcome the diffraction limit, such as double/multiple patterning photolithography. Recently, a derivative of UV photolithography called dual-layer photolithography was reported can generate sub-micron linear patterns. In addition to linear patterns, here, we report a double patterning method to get via patterns using dual-layer photolithography. The photomask design rule for double patterning dual-layer photolithography is studied and presented in this work. For demonstration purpose, an example GDSII via file from practical application contains> 10,000 vias was used. The vias with original size of 4 μm would be reduced to 300 nm after the double patterning process.