A Finite Element Model for Predicting the Collapse of Short and Large Two-Line Patterns During Drying Process in Photolithography

Photolithography is one of the main mass nano-production processes. Smaller devices are always aimed to save material and energy. Manufacturing small devices by photolithography is a challenge, due to the risk of collapse of patterns during the drying of rinse liquid. One of the main pattern shapes is the two-line parallel. In our previous study, an analytical model was developed for predicting the collapse of large (L/d, LAR>20; see Fig. 1) two-line parallel patterns [1]. This model assumes the rinse interface shape is cylindrical. Knowledge of the rinse interface shape is needed to define the forces contribute to collapse, i.e. Laplace pressure and surface tension force at the three-phase line. In the current study, a Finite Element (FE) model is developed to predict the collapse of short (LAR<20) and large (LAR>20) two-line parallel patterns. Rinse liquid shape and its curvature are found using Surface Evolver (an interactive program for the study of surfaces shaped by surface tension, gravitational and other energies). Another finite element method (i.e. ANSYS 11.0) is used to find the pattern deformation. It was found that the pattern deformation decreases by decreasing the LAR value. It is important as for the cases that due to the design specifications, selection of the pattern material and rinse liquid is restricted, by changing the LAR value one may resolve the collapse problem.