Characterization of assist features on impact of mask error enhancement factors for sub-0.13 um technology

Abstract

Resolution enhancement techniques, such as phase shifting, OPC and assist features were greatly used to enable sub-wavelength features printing using 248 nm lithography due to the delay of 193 nm lithography. Assist features, also known as scattering bars, was utilized to improve the image quality for isolate lines for the sub-wavelength features as well as to improve the overlapping process latitude. In this study, MEEF was fully characterized with assist features. Great improvement in MEEF was observed by applying assist features to the sub-0.13 um technologies. The effect of mask error enhancement by the deviation from the designed line width of the image line with different sets of placement and width sizes of the assist features was been studied. The impact of MEEF by different placement of the assist features was observed. In addition, a simulation program had been used for the study of the deviation in the placement of the scattering bars as well as its size. It was shown that simulation aerial image results were quite matching with imperial results. The effect of annular illumination had also been examined as compared to conventional illuminations.