Multifold study of volume plasma chemistry in Ar/CF4 and Ar/CHF3 CCP dischargesстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 26 марта 2018 г.
Аннотация:Low-pressure RF plasma in fluorohydrocarbon gas mixtures is widely used in the modern microelectronics, e. g. in etching of materials with low dielectric constant (low-k materials). Multifold experimental and theoretical study of radio frequency capacitively coupled plasma at 81 MHz in Ar/CF<sub>4</sub>/CHF<sub>3</sub> has been carried out at 50 mTorr and 150 mTorr gas pressures. The wide set of experimental diagnostics together with the hybrid PIC MC model calculations was applied to the detailed study of the plasmas. Measurements of F atoms, HF molecules and CF<sub>x</sub> radicals, electron density, electronegativity and positive ion composition were performed. Absolutely calibrated VUV spectrometry was carried out to measure VUV photon fluence towards the electrode. This combined experimental and model approach allowed to establish fundamental mechanisms of charged and neutral species elementary reactions. Dissociative charge transfer reactions and fluoride transfer reactions influence a lot the main ion (CF<sub>3</sub><sup>+</sup>, CHF<sub>2</sub><sup>+</sup>) composition in Ar/CF<sub>4</sub>/CHF<sub>3</sub> plasma. The mechanisms of heavy ions formation in Ar/CHF<sub>3</sub> are also discussed. The important role of additional attachment mechanisms (besides dissociative attachment to feedstock gases, CF<sub>4</sub> , CHF<sub>3</sub>) was analyzed. The catalytic chain mechanism including HF molecules that defines CF<sub>x</sub> kinetics in Ar/CHF<sub>3</sub> plasma was validated.This multifold approach enabled us to determine the complicated plasma chemical composition of active species and the fuxes of VUV photons to the surface of the processed material that is important for understanding of low-k damage.