FTO 필름 식각액에 관한 융합연구

Convergence Study on FTO Film Etchant

Abstract

완전 수입에 의존하는 ITO를 대체할 수 있는 FTO 필름에 회로를 형성시킬 수 있는 식각액을 제조하였다. 이 식각액은 불화물 1 ~ 30량%, 산 1 ~ 20량%, 계면활성제 0.5 ~ 5 중량%, 용매제 5 ~ 20 량%, 부식억제제 0.5 ~ 10중량%, 나머지는 물로 이루어진다. 이 식각액은 드라이필름을 이용한 식각공정이 가능하여 비용을 절감할 수 있으며, 식각액의 거품발생 및 찌꺼기가 발생하지 않는 특징이 있다. 식각액의 특성은 100nm 두께의 FTO를 2분 만에 식각할 수 있었고 이때 $50^{\circ}C$의 식각액 온도를 유지하였다. 2분 식각액에 넣었을 때 -0.00364%의 언더컷을 얻었다. Cd, Pb, Hg, Cr 성분 등의 환경유해물질은 측정되지 않았다. 희토류가 나지 않는 우리나라에서 FTO를 활용하면 국산화 및 수입대체효과를 이룩할 수 있다.

An etchant capable of forming a circuit in an FTO film that can replace ITO, which depends on full imports, was prepared. The etching solution is composed of 1 to 30% by weight of fluoride, 1 to 20% by weight of acid, 0.5 to 5% by weight of surfactant, 5 to 20% by weight of solvent, 0.5 to 10% by weight of corrosion inhibitor and the balance of water. This etchant can be etched using a dry film, thereby reducing the cost, and is free from bubbles and residue of the etchant. The characteristics of the etchant were etched in a time of 2 minute with a 100 nm thick FTO, and the etchant temperature was maintained at $50^{\circ}C$. An undercut of -0.00364% was obtained when put into a 2 minute etching solution. No harmful substances such as Cd, Pb, Hg and Cr components were measured. The use of FTO in Korea where rare earths do not exist can achieve localization and import substitution effect.

Fig. 1. Etching Speed according to fluorine compounds

Fig. 2. Etching Speed according to Acid Type

Fig. 3. Etching Speed according to fluorine compound content

Fig. 4. Etching Speed according to Acid Content

Fig. 5. Surface tension test according to surfactant content

Fig. 6. Confirmation of pattern formation(L: before etching, R: after etching)

Fig. 7. Testing flow chart for RoHS: Cd/Pb/Hg/Cr⁶⁺ testing

Fig. 8. Wet etching pretreatment process

Fig. 9. FIB measurement result.(1st angle)

Fig. 10. FIB measurement result.(2nd angle)

Fig. 11. Before etching

Fig. 12. Etching After 90seconds

Fig. 13. Etching After 120seconds

Fig. 14. Sn content for dipping time

Fig. 15. Ingradient analysis(SEM/EDS)

Table 1. Surface tension according to surfactant content

Table 2. Etchig Condition Result

Table 3. Hazardous substance inspection

Table 4. Undercut result