Process optimization for shallow trench isolation etch using computational models

In today’s advanced semiconductor process manufacturing, critical dimensions of device features have decreased to a few nanometers while the aspect ratios have increased beyond 100. The cost of process development has significantly increased and the performance of the lithography and plasma etch patterning processes are critical to the success of ramping a new technology node toward profitable high-volume manufacturing. In this paper, a three-dimensional Monte Carlo-based feature scale model, ProETCH®, has been developed for modeling etch process with the capability of optimizing the process by solving forward and inverse problems. The shallow trench isolation etch process in self-aligned double patterning was investigated. The mechanism of silicon etch by Ar/Cl2 plasma was developed with experimental data as a reference. The developed model captures the trends and has quantitative accuracy in comparison to the experimental data, and can be used to identify the different fundamental pathways which contribute to the profile metrics. The developed model was then used to solve the forward problem, which is to predict profiles at different process conditions, and the inverse problem, which is to search for the process conditions (e.g, power and pressure) which could result in desirable profiles.