Molecular Dynamics simulations of the etching process with ReaxFF

Within the FreeMe project, IDENER is exploring etching processes between various substrates and Piranha solution. One substrate of particular interest, ABS, has successfully undergone simulated etching with piranha solution.

Their most promising simulation method, the “molecular gun”, involves several key steps. First, they generate and stabilise an ABS block within a simulation box. Molecules of piranha solution are then “fired” from a designated volume above the block, with randomised x, y, and z coordinates. This approach enables the piranha solution to impact the ABS block under various concentrations. Four different sulfuric acid to hydrogen peroxide ratios were tested to determine the most effective composition for etching. The goal was to observe penetration depth, mean square displacement (MSD), diffusion rates, ABS mass variation, and species formation over time.

Key achievements so far include:

• Developing a functional “molecular gun” that allows flexible concentration adjustments and accurate piranha solution deposition onto the ABS block.
• Identifying optimal launch energies that ensure effective penetration without excessively piercing the block.
• Logging and analysing the resulting chemical species, as well as tracking changes in the ABS block’s mass over time.

This approach provides valuable insights into the ideal conditions for ABS etching and lays the groundwork for further exploration of substrate-piranha interactions.