A NOVEL SIMULATION METHODOLOGY FOR ISOTROPIC GAS PHASE ETCHING
Behraad Bahreyni and C. Shafai
Keywords: MEMS, Simulation, Etching, Xenon Difluoride
A novel methodology for the simulation of isotropic gas phase etching of a substrate is presented. In this method, individual substrate atoms are removed upon physical impingement of etchant gas molecules.
The effects of different etch mechanisms are included in a few simulation parameters; namely, the mean free path (MFP) of the etchant gas molecule, the reaction probability, and a scaling factor. This method reduces the complexity of the simulation algorithm to a large degree by not involving the chemistry behind the reactions. This algorithm can easily be used for simulation of isotropic gas phase etching of different materials.
Although computationally more intensive, the simulation program can accurately predict complicated profiles for different sizes of mask openings. Good agreement was found between experimental measurements and predicted profiles. The experimental data was taken with a profilometer from silicon samples etched by xenon difluoride.
Etch anisotropy can be introduced by restricting the motion of etchant gas molecules to a certain direction. This will enable simulation of common anisotropic gas phase etching processes such as RIE.
NSTI Nanotech 2003 Conference Technical Program Abstract