Paper PS-ThP2
Multidimensional Plasma Simulations of an SF₆/O₂ Etch

Thursday, November 12, 2009, 6:00 pm, Room Hall 3

Sulfur Hexafluoride (SF₆) is the plasma processing gas that is used industry-wide in a range of processes for the dry etching of silicon. However, the performance and efficiency of different processes and machines can vary widely. Through simulation we can gain significant insight into the optimization problem and provide a low cost means for further development.

SF₆ is also very bad for the environment with a Greenhouse Warming Potential that is 22,000 times that of CO₂. Therefore it is vital that SF₆ is used sparingly and efficiently in every process. Here, simulation can help to find ways of remediating harmful waste gases and optimize the process for typical processing goals (e.g. etch rate, uniformity) as well as improving SF₆ consumption efficiency and other environmental measures.

Here we present an full chamber 2D simulation of an SF₆/O₂ silicon etch process, building upon previous calculations of SF₆ plasma chemistries using Quantemol-P [1]. Etch rate, pressure and power trends along with chamber wide contour plots of gas-phase species concentrations and fundamental plasma properties are considered.

To perform these calculations and build this model a new software tool is being constructed and will be demonstrated. The plasma simulation itself is run using a set of algorithms and codes based on HPEM [2]. The new code will integrate with outputs from Quantemol-N [3], which provides data on molecular processes, and Quantemol-P. It will provide

a set of design and specification tools, along with an expert system for running HPEM and a design of experiments (DOE) type calculation system.

[1] J.J. Munro and J. Tennyson, J. Vacuum Sci. Tech. A, 26, 865 (2008)

[2] R.J. Hoekstra, Michael J. Grapperhaus and M.J. Kushner, J. Vacuum Sci. Tech. A, 15, 1913 (1997).