Designing of Bridges on Stencils: Calculation and Simulation

This project focused on optimizing bridge parameters to minimize bending of stencils in stencil lithography. The study focused on a stencil with U-shaped openings. Initial theoretical analysis was conducted to understand the mechanical behavior of the stencil post-deposition, establishing crucial formulas. Utilizing COMSOL simulation software, a study of bridge parameters, including width, length, number, and placement, was undertaken. This investigation provided valuable insights into how these parameters influence structural stability and optimization. The study identified that corner bridges effectively reduce deflection at the tip and lower stress concentration in bridges. Wider bridges were found to reduce deflection at the beam tip and distribute the load more uniformly, minimizing overall deflection and stress concentrations. Optimizing bridge length was found crucial; while decreasing length enhanced stability and reduced x-axis deflection, it also managed stress concentrations in the SiN film. An optimal length balanced flexibility and stiffness to minimize deflection and stress. The number and placement of bridges were also critical. Placing bridges closer to the tip and increasing their number reduced deflection and stress along the bridges length. The study, conducted solely through simulation, suggests the need for experimental validation to confirm results in real-life conditions. Future research directions include exploring alternative material depositions, varying thicknesses of deposited material, and investigating alternative stencil opening shapes to further enhance understanding in the use of stencil for stencil lithography.