Study And Implementation Of Spatial Filtering Technology For Resolution Enhancement In Optical Lithography

As the technology node of IC(integrated circuits) manufacturing came into the VDSM(Very Deep Sub-micron) era, the so-called Sub-Wavelength Lithography has been widely used. However, Optical Proximity Effect(OPE) happens when the feature and spacing dimension are shorter than half of the wavelength of lithography light source. OPE will result in the sharp difference between the wafer and the original layout, which will make the circuits invalid and effect the yield. Resolution Enhancement Technology(RET) has been developed to solve the problem. Being used widely, RETs have become the focus of the research in the global IC industry. Spatial filtering technologies including Off Axis Illumination(OAI) and Pupil filtering(PF) are new RETs. These technologies can enhance the resolution of lithography by changing the distribution of the object's spectrum in and out of the pupil, and then decreasing the object's lower frequency parts and increasing higher frequency parts.Modeling of the lithography is essential to the RETs. The main research of this paper focuses on the uses of spatial filtering technologies in improving the performance of the lithography models. The manufacturing processes of the IC and lithography technologies are introduced in this paper. Also, the paper presents a new lithography simulation tool called Litholab which provide a research platform of lithography modeling. Optimization strategies of illumination model and pupil function are introduced. And a new source model with continuous representation and a new pupil function with consideration of lens aberrations are presented as well. The results of experiments prove that new models provide higher precision than normal models.