| AVS 54th International Symposium | |
| Plasma Science and Technology | Monday Sessions |
| Session PS1-MoM |
| Session: | Plasma Modeling |
| Presenter: | G. Wenig, Qimonda, Germany |
| Authors: | G. Wenig, Qimonda, Germany A. Kersch, Qimonda, Germany W. Jacobs, Qimonda, Germany S. Barth, Qimonda, Germany A. Henke, Qimonda, Germany J. Sobe, Qimonda, Germany A. Steinbach, Qimonda, Germany S. Wege, Qimonda, Germany M. Reinicke, Dresden University of Technology, Germany |
| Correspondent: | Click to Email |
Silicon etching based on a HBr/O2/NF3 plasma generated in a dual (2 and 60MHz) frequency capacitively coupled MERIE plasma reactor is used to fabricate DRAM trench capacitors. To maintain a constant capacitance per memory cell an optimum aspect ratio and trench shape with respect to capacitance and cost has to be achieved. In this contribution a high aspect ratio silicon etch selective to an oxide mask is studied with respect to the influence of pulsing the rf sources on the ion energy and angular distributions. Particle-in-cell and efficient hybrid fluid-kinetic simulations are used to investigate the consequences of source and bias pulsing. Both methods use identical ion-neutral collision models. The required differential cross sections have been computed ab initio. Charge exchange processes are treated with a constant charge exchange probability. The resulting ion and neutral distributions are used as input for a Monte Carlo simulation of particle transport in the trench. Pulsing frequencies, duty cycles, and phase shifts are varied separately. Modeling results and experimental data show the beneficial effects of pulsing on etch results.