Enhancing Si<sub>3</sub>N<sub>4</sub> Selectivity over SiO<sub>2</sub> in Low-RF Power NF<sub>3</sub>–O<sub>2</sub> Reactive Ion Etching: The Effect of NO Surface Reaction
Nguyen Hoang Tung,
Heesoo Lee,
Duy Khoe Dinh,
Dae-Woong Kim,
Jin Young Lee,
Geon Woong Eom,
Hyeong-U Kim,
Woo Seok Kang
Affiliations
Nguyen Hoang Tung
Mechanical Engineering, KIMM Campus, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
Heesoo Lee
Semiconductor Manufacturing Research Center, Korea Institute of Machinery and Materials (KIMM), Daejeon 34103, Republic of Korea
Duy Khoe Dinh
R&D Center, Naieel Technology, Daejeon 34104, Republic of Korea
Dae-Woong Kim
Mechanical Engineering, KIMM Campus, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
Jin Young Lee
Department of Nano-Devices & Display, Korea Institute of Machinery and Materials (KIMM), Daejeon 34103, Republic of Korea
Geon Woong Eom
Semiconductor Manufacturing Research Center, Korea Institute of Machinery and Materials (KIMM), Daejeon 34103, Republic of Korea
Hyeong-U Kim
Semiconductor Manufacturing Research Center, Korea Institute of Machinery and Materials (KIMM), Daejeon 34103, Republic of Korea
Woo Seok Kang
Mechanical Engineering, KIMM Campus, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
Highly selective etching of silicon nitride (Si3N4) and silicon dioxide (SiO2) has received considerable attention from the semiconductor community owing to its precise patterning and cost efficiency. We investigated the etching selectivity of Si3N4 and SiO2 in an NF3/O2 radio-frequency glow discharge. The etch rate linearly depended on the source and bias powers, whereas the etch selectivity was affected by the power and ratio of the gas mixture. We found that the selectivity can be controlled by lowering the power with a suitable gas ratio, which affects the surface reaction during the etching process. X-ray photoelectron spectroscopy of the Si3N4 and QMS measurements support the effect of surface reaction on the selectivity change by surface oxidation and nitrogen reduction with the increasing flow of O2. We suggest that the creation of SiOxNy bonds on the surface by NO oxidation is the key mechanism to change the etch selectivity of Si3N4 over SiO2.
