Analysis of line edge roughness using probability process model for chemically amplified resists

Various factors are considered as causes of line edge roughness (LER), such as fluctuation in energy particle density (shot noise), local acid density, solubility of polymer molecules and their size. Most analyses/simulations as for resist patterns assumes resist as continuous matter, and its solubility (dissolution rate) is defined as a continuous function of process condition such as exposure dose. In reality, however, resist pattern is a large cluster of polymer molecules and solubility of each molecule takes only two values (e.g. soluble or insoluble). Macroscopically observed dissolution rate is considered to represent probability of main reaction and developer percolation. In this sense, LER means fluctuation in acid catalyzed (main) reaction to determine molecular solubility combined with developer percolation. Here, the developer percolation also depends on geometrical arrangement of main reaction. In this paper, line edge roughness (LER) in chemically amplified resists (CARs) is analyzed as a fluctuation in acid catalyzed reaction to determine molecular solubility and developer percolation.