| AVS 63rd International Symposium & Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS-MoM |
| Session: | Advanced FEOL/Gate Etching |
| Presenter: | Sergey Voronin, TEL Technology Center, America, LLC |
| Authors: | S. Voronin, TEL Technology Center, America, LLC J.R. Sporre, International Business Machines – Research Division S. Kanakasabapathy, International Business Machines – Research Division A. Ranjan, TEL Technology Center, America, LLC |
| Correspondent: | Click to Email |
Moore’s law extension in the semiconductor industry requires processing of features at nanometer scale. Approaching sub-10NM technological fabrication we face more stringent requirements to the etch process (high anisotropy and high selectivity to the mask films).
We present peculiarities and new challenges of 3D gate etch processing in halogen-based plasmas. These include by-product -free etching of narrow features, “FIN-Gate” corner residue removal, prevention of merging of the neighboring gates and advanced selectivity control to the FIN oxide. To combine all these in one process, we need multiple unique steps responsible for certain stages of etching. The etching mechanisms and dependence of the etching properties (selectivity, anisotropy and etch rate) on the plasma discharge parameters (electron temperature, ion and radical densities, ion energy) will be described for each step. We have successfully approached the 7NM technological node at aspect ratios and, etch depths up to 6:1 and 160 nm, respectively, with a potential for the next technological generation.
An additional subject of discussion is related to surface-plasma interactions between charged and neutral species in HBr plasmas. Formation and deposition of non-volatile bromine-containing by-products SiBrx (x=1,2) and SiBrxOy can result in clogging of narrow features, etch profile distortion, limited etching depth and residual Si at high aspect ratios. These non-volatile species are accumulated on the process chamber wall, desorb to the gas phase and can re-deposit on the processed wafer for long times – well after the main etch process is over. We demonstrate the importance of the chamber wall chemistry condition and plasma discharge parameters in formation and re-deposition of these species. Chamber wall surface cleaning by fluorine-containing plasmas and lowering the source power resulted in significantly smaller amounts of by-product and can be used as profile control knobs in the process.