Impact of RSF with variable coefficients for CD variation analysis including OPC

Optical lithographic processing continues to be the mainstream technology for ⩽0.18 μm generations with the development of wavelength resolution (KrF, ArF), resolution enhancement technology (RET) such as off-axis illumination and phase shifting masks. The ULSI manufacturing process faces CD variation as a new issue (Pforr et al., 1995). Two major factors of CD variation are process variation and the optical proximity effect, which depends on the pattern layout. Hence, statistical gate CD control considering the CD variation caused by these two factors is a key issue in the ULSI manufacturing process. In this paper, we describe the RSF with variable coefficients for CD variation analysis, including mask bias OPC (optical proximity correction). The RSF with variable coefficients to lens conditions NA and σ is newly developed, indicating the nonlinear dependence of CD on the focus position. This approach allows CD variation analysis including mask bias OPC, even when the line width comes close to the stepper wavelength