Sub-0.10 μm Lithography technology with resolution enhancement technique

Abstract

Reduction of feature sizes in semiconductor circuits has pushed photolithography to print features below the wavelength of the light source. However, severe optical proximity effects and small depth of focus for isolated lines have brought challenges to sub-wavelength lithography for application to 0.10 μm technology using 248 nm and 193 nm scanners. Resolution Enhancement Technique (RET) is applied extensively for 0.10 μm technology. The use of attenuated phase shift masks to improve the process latitude is well known from literature, however higher transmission attPSM is limited by side-lobe printing. In order to achieve desired critical dimension control, OPC is necessary needed with PSM. Although off-axis illumination improves resolution for dense features, it degrades exposure latitude and depth of focus for sparse features. Applying scattering bars (SB), also called assisting features, to an isolated line can modify the diffraction pattern similar to that generated by dense lines. A comprehensive study on how scattering bars could affect the performance of isolated and dense lines by adjusting the bar size and placement to the main feature edges as well as changing the illumination condition and exposure energy are performed. It is showed that SB is able to increase the depth of focus for isolated line and an acceptable 0.10 μm patterning process is achieved. Furthermore, SB-OPC helps minimize the negative impact due to lens aberration on isolated features. The results demonstrate that SB-OPC is one of the most manufacturable solutions for sub-0.10 μm line patterning using current DUV lithography.