Paper PS2-ThM10
Investigation of Micro-Trenching, Bowing and Charge Accumulation on Mask using a Dry Etching Simulator Designed for Low-Pressure High-Density Plasma

Thursday, October 23, 2008, 11:00 am, Room 306

The development of new sub-micron technologies requires a fundamental understanding of device fabrication processes in order to be able to push the technology to its limits. In particular, in the context of plasma etching, the quality of patterning critically depends upon a number of plasma characteristics and on the surface reactivity with respect to the plasma species. Numerical simulation is of great interest for providing insights into the physics underlying various processes and to indentify the etching control mechanism. We developed a cellular Monte-Carlo-based dry etching simulator designed for low-pressure high-density plasma. The simulation code has been validated for various experimental profiles, namely Si, SiO₂, SrTiO₃ and Pt thin films etched in Ar and Ar/Cl₂ plasmas. The observations of both micro-trenching, due to ion scattering on sidewalls, and bowing, due to lateral etching, are well reproduced for various profile widths from 4 μm to 500 nm, which validates the simulation approach. We also investigated the effect of electrical mask charging during Pt etching in Ar plasma. Assuming an electrical field near the mask surface through positive charge accumulation yields the angular deviation of impacting ions. It will be shown that the etching profile obtained by our simulation is in good agreement with that observed from scanning electron microscopy.