Single pulse laser removal of indium tin oxide film on glass and polyethylene terephthalate by nanosecond and femtosecond laser

Chern Yang Leong,Chen Hon Nee,Teck Yong Tou,Siaw Foon Lee,Seong Ling Yap,Teng Sian Ong,Seong Shan Yap,Yoong Tatt Chin,Guang Liang Ong

doi:10.1515/ntrev-2020-0115

Abstract

Abstract Indium tin oxide (ITO) is the most important transparent conducting electrode to date and the candidate for ultrafast signal processing in telecommunication region. ITO is normally selectively removed in a multiple-steps process for device application. In this work, we aimed to study single pulse removal of ITO-coated glass and PET by using a nanosecond (ns) laser (266 nm) and a femtosecond (fs) laser (1,025 nm) where each process is dominated by either linear or nonlinear process. For ns laser, ITO was removed from PET substrate at 0.01 J/cm2. Detachment likely occurred via thermal-induced process because of the high absorption by both ITO and PET and the thermomechanical properties of PET. At higher laser fluence (∼0.04 J/cm2), the ITO films on both substrates were damaged, and at 1.34 J/cm2, ITO was ablated from the glass substrate. For fs laser removal via nonlinear process, ITO was removed from PET substrate at 0.3 J/cm2, but at 0.8 J/cm2, the PET substrate was also modified. ITO layer was partially removed from glass substrate by fs laser pulse at 0.3 J/cm2 and full removal only occurred at 1.7 J/cm2. Thus, the fluence range for single fs pulse removal of ITO/PET was 0.3–0.8 J/cm2 and >1.7 J/cm2 for ITO/glass.

Highlights

Tin-doped indium oxide or indium tin oxide (ITO) is the most important transparent conductive oxide (TCO) as transparent electrodes due to their excellent electrical conductivity and optical transparency in the visible spectrum [1,2]
The results suggest that ablation is to occur because of high nonlinear absorption of ITO
The results show that ITO removal from polyethylene terephthalate (PET) can be achieved by using the 266 nm, ns laser (0.01 J/cm2) because of the high linear absorption of the ns laser pulse and the thermomechanical properties of PET substrates

Summary

Introduction

Tin-doped indium oxide or indium tin oxide (ITO) is the most important transparent conductive oxide (TCO) as transparent electrodes due to their excellent electrical conductivity and optical transparency in the visible spectrum [1,2]. It is used in almost all optoelectronic applications such as displays, touch panels, solar cells, and sensors [3,4]. Another approach for ITO patterning is to utilize lasers in a dry process which offers higher controllability, potentially negating the necessity of masking, reducing the complexity of patterning process [10,11,12,13,14,15]

Objectives

Results

Discussion

Conclusion