Fig. 4: Molecular dynamics simulations of photoresist polymers in liquid films.
From: Cryo-electron tomography reconstructs polymer in liquid film for fab-compatible lithography
a Typical structural changes from poly(methacrylate) to poly(methacrylic acid) in chemical amplified resist occur after ultraviolet exposure and post exposure baking. b Simulation showing a poly(methacrylic acid) molecule (u = v = w = 10) diffuses to gas-liquid interface from solution interior. c z-direction distribution functions of poly(methacrylic acid) (red) and water (purple) extracted from (b). d Potential of mean force of poly(methacrylic acid) derived from the z-direction distribution function in (c). e-f MD simulations showing two separated poly(methacrylic acid) molecules diffuse to gas-liquid interface and exhibit cohesional entanglement. g Energies of different states of poly(methacrylic acid) molecules. The cohesional entanglement between two poly(methacrylic acid) molecules leads to a decrease in energy. Water molecules are depicted as cyan triangles, and the C, O, and H atoms in poly(methacrylic acid) are colored black, red, and white, respectively.
