Integrated non-SO2 underlayer and improved line-edge-roughness dielectric etch process using 193nm bilayer resist

We present an integrated reactive ion etch (RIE) process using bilayer (a top imaging layer and a bottom underlayer) thin film imaging system to push the limits of 193nm wavelength photolithography. Minimizing the line-edge roughness (LER) and maintaining the critical dimension (CD) of the transferred pattern are important in high-resolution RIE. Along with LER and CD issues and shrinking ground rules, deleterious effects of SO2 in the underlayer etch chemistry necessitated the development of non-SO2 chemistry. Thus a N2–H2–CO chemistry was developed and integrated with the etch process of underlying borophosphosilicate glass using Ar–O2–C4F8–CO–CH3F chemistry.