An In-house Rigorous Etching Model for Process Recipe Tuning

As device critical dimensions (CDs) continue to shrink, plasma etching of Si structure, such as shallow trench isolation (STI), requires precise control of ion energy and angular spread. Sophiscated tuning parameters, such as multi-frequency pulsing and cyclic processes, has been introduced to meet the requirments. With the increasing complexity of the etching processes and the large number of process variables, a rigorous etching model becomes attractive as it can not only provide key insights into the fundamental etching and deposition mechanisms but also explore the parameters beyond the existing process window.

In this work, a coupled reactor-feature model is developed in house at TSMC. The reactor model solves the plasma continuity equation with Poisson's equation for density and potential, and electron energy equation for electron temperature. The feature model uses Monte Carlo techniques to simulate the feature evolution of the etching process. The feature model uses ion and neutral fluxes, and energy distribution from the reactor model. The coupled reactor-feature model is used to investigate the etching process and for the recipe tuning.