To improve the etch rate of Si3N4 thin film, H2SiF6 is added to increase etching rate by more than two times. SiO3H2 is gradually added to obtain a selectivity of 170: 1 at 600 ppm. Moreover, when SiO3H2 is added, the etching rate of the SiO2 thin film increases in proportion to the radius of the wafer. In Si3N4 thin film, there is no difference in the etching rate according to the position. However, in the SiO2 thin film, the etching rate increases in proportion to the radius. At the center of the wafer, the re-growth phenomenon is confirmed at a specific concentration or above. The difference in etch rates of SiO2 thin films and the reason for regrowth at these positions are interpreted as the result of the flow rate of the chemical solution replaced with fresh solution.

Abstract
 1. 서 론
 2. 실험 방법
 3. 실험 결과
 4. 결 론
 References

• 이승훈(㈜제우스) | Seunghoon Lee (ZEUS) Corresponding author
• 모성원(㈜제우스) | Sungwon Mo (ZEUS)
• 이양호(㈜제우스) | Yangho Lee (ZEUS)
• 배정현(㈜제우스) | JeongHyun Bae (ZEUS)