In many atmospheric plasmas utilized for various industrial applications, gases such as argon and oxygen are often introduced for assisting stable plasma generation and particular processes. In this thesis, characteristics of Ar plasmas are studied, and effects of Ar and O2 mixing on an atmospheric plasma produced in the ambient air are discussed. In addition, surface treatment and PR ashing were attempted for the applications of atmospheric plasma.
Breakdown voltage and rotational temperature of the argon plasma were investigated based on electrical and optical measurements. The breakdown voltage of Ar plasma was 420 V (at Ar 10 lpm, 3mm bottom gap) and rotational temperature was 470 K (at 300 W). In the case of Ar and $O_2$ mixing, it was shown that the breakdown voltage was increased from 435 V to 450 V (at Ar 10plm fixed, $O_2$ 0sccm ~ 10 sccm) due to additional electron energy loss channels wuch as bivrationally-and rotationally- excited states, molecular dissocation etc. The rotational temperature increased from 490 K to 570 K (at 300 W). Excessive addition of $O_2$, however, reduced the plasma uniformity and stability due to the large electron affinity of oxygen molecules.
Atmospheric Argon plasmas enhanced the wettability of material surfaces such as paper, glass, Si wafer. As an increase of plasma exposure time and amount of oxygen addition, the PR ashing rate was increased. The increase of $O_2$ addition for enhancing ashing rate caused higher breakdown voltage, rotational temperature, and lower uniformity and stability. Therefore, a proper mixing fraction is required for any particular application.
상압 플라즈마를 안정적으로 발생시키고, 응용을 위해 주로 사용되는 기체는 아르곤과 산소이다. 본 논문에서는 아르곤 플라즈마의 특성과 아르곤과 산소의 혼합에 따른 플라즈마의 특성변화에 대해서 살펴보고, 응용으로 표면처리와 PR 애싱에 대해서 연구하였다. 아르곤(10 lpm) 플라즈마는 420 V 의 전리전압과 470 K 의 회전온도(300 W)를 가지는데, 산소의 혼합에 따라(0 ~ 10 sccm) 전리전압은 435 V 에서 450 V 로, 회전온도는 490 K 에서 570 K 로 증가하였다. 지나친 산소의 혼합(10 sccm 이상)은 우수한 전자친화력으로 플라즈마의 공간 균일도를 감소시킨다. 아르곤 플라즈마를 이용하여 다양한 물질의 표면을 처리하면 친수성으로 변화하였고, 아르곤에 산소의 혼합량이 증가함에 따라 PR 애싱률이 증가하였다. 하지만 산소량의 증가는 전리전압과 회전온도를 증가시키고, 균일도를 감소시킨다. 따라서 특정한 응용을 위해서는 아르곤과 산소의 적절한 혼합이 요구된다.
