| AVS 64th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Wednesday Sessions |
| Session PS-WeA |
| Session: | Modeling of Plasmas |
| Presenter: | Guillaume Le Dain, STMicroelectronics / CNRS-IMN, France |
| Authors: | G. Le Dain, STMicroelectronics / CNRS-IMN, France A. Rhallabi, Cnrs - Imn, France S. Elidrissi, University of Nantes C. Cardinaud, Cnrs - Imn, France A. Girard, Cnrs - Imn, France F. Roqueta, STMicroelectronics, France M. Boufnichel, STMicroelectronics, France |
| Correspondent: | Click to Email |
Bosch process is currently used for semi-conductors devices manufacturing. This technique performs high aspect ratio features by alternating SF6 and C4F8 plasma pulses. These features are needed for some micrometric scale systems such as Microelectromechanical Systems (MEMS) and System in Package (SiP). One of the problem encountered in silicon etching under Bosch process is the difficulty to minimize the scalloping effect characterized by the propagation of the ripples along the sidewall and to maintain a high etch rate.
Usually, a pure SF6 plasma pulse for etching step and pure C4F8 plasma pulse for deposition step are used in silicon Bosch process. The aims of our study are to analyze the effect of oxygen addition to both SF6 and C4F8 plasmas pulse on the silicon etching profile evolution and to understand how the oxygen could improve the etching anisotropy and minimize the scalloping effect. Indeed, previous works reveal that the addition of oxygen to SF6 plasma for silicon etching under cryogenic process contributes to the sidewall passivation of etched silicon and thus to the improvement of the anisotropy [1]. In this context, we have added O2 gas to our SF6 and C4F8 plasmas module as well as sheath and surface modules of silicon etching simulator. This is to investigate its effect on the silicon etching profile evolution under Bosch process [2]. Our etching simulator is composed of three modules: 0D plasma kinetic module, 2D sheath module and 2D surface module. It allows the prediction of the silicon etching profile evolution as a function of the operating conditions such as power, pressure, flow rate, plasmas pulses times and bias.
The effects of %O2 on the electrical and kinetic properties of plasmas are analyzed. Moreover, its impact on the silicon etching profile evolution under the mask is presented.
Comparisons between the simulation and the experiments give satisfactory agreements for both plasma discharges and silicon etching profiles.
[1] R Dussart, T Tillocher, P Lefaucheux and M BoufnichelJ. Phys. D: Appl. Phys.47 123001 (2014)
[2] G. Le Dain, A. Rhallabi, M. C. Fernandez, M. Boufnichel and F. RoquetaJ. Vac. Sci. Technol. A35 (3), May/Jun 2017 (To be published)