Etching of Si 3 N 4 by SF 6 /H 2 and SF 6 /D 2 plasmas

• Published in: Journal of physics. Conference series 2020-12, Vol.1697 (1), p.12222
• Main Authors: Pankratiev, P A, Barsukov, Yu V, Kobelev, A A, Vinogradov, A Ya, Miroshnikov, I V, Smirnov, A S
• Format: Article
• Language: English
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1697/1/012222

Selective plasma etching of silicon nitride (Si 3 N 4 ) over silicon oxide (SiO 2 ) is one of critical steps in the nanofabrication processes, where a direct plasma etching of Si 3 N 4 is required for some applications. It was reported recently that Si3N4 etching by remote plasma source can be initiated by the vibrationally excited HF(v) molecules at the low concentration of atomic fluorine. Generally, the main source of HF(v) in plasma is reaction of atomic fluorine with H2 molecule. Due to this fact, the kinetic isotope effect should be observed during Si3N4 etching if replace the H 2 source gas on deuterium gas (D 2 ). The data presented here are the Si 3 N 4 and SiO 2 etching by the SF 6 /H 2 and SF 6 /D 2 plasmas. A different amount of H 2 and D 2 have been added to the SF 6 discharge during the Si 3 N 4 and SiO 2 etching. It was shown that at low H 2 /D 2 flow rate the Si 3 N 4 etch rate is lower in the SF 6 /D 2 discharge. This one confirms the hypothesis about Si 3 N 4 etching by HF(v) and indicates on the fact that HF(v) gives contribution to Si 3 N 4 etching by the direct plasma (not only by the remote plasma) at relatively high concentration of atomic fluorine.