Ju-Liang He^1,2, Ping-Yen Hsieh^1,2, Ying-Hung Chen^1,2, Tzu-Hou Chan³, Yao-Kuang Yang³, Thomas Schütte⁴, Ralf Bandorf^2,5
1Feng Chia University, Taichung City, Taiwan
²Fraunhofer Innovation Platform for Surface and Production Engineering for Optical and Electrical Systems at the Feng Chia University (FIP-SPE@FCU), Taichung City, Taiwan
³Dah Young Vacuum Equipment Co., Ltd., Taiwan
⁴PLASUS GmbH, Mering, Germany
⁵Fraunhofer Institute for Surface Engineering and Thin Films IST, Braunschweig, Germany
Real-time film deposition control in industrial roll-to-roll (R2R) PVD coaters is critical for managing production costs and ensuring long-term operational stability. Among the various control techniques, optical emission spectroscopy (OES) stands out for its ability to monitor in-situ changes in plasma species, which play a vital role in achieving successful film deposition. In this study, OES was integrated into an R2R HiPIMS coater to enable real-time correction of plasma spatial distribution and long-term operational stability through active feedback control.
The experimental setup utilized a drum-type R2R HiPIMS coater for copper deposition, featuring a web width of 660 mm and a copper sputter cathode length of 1050 mm. Three collimators, spaced 250 mm apart, were positioned along the cathode. By optimizing the argon gas flow distribution across the sputter cathode and actively controlling the HiPIMS output average power during a continuous 5-hour operation, the difference in the OES signal intensity ratio of CuII/(CuI+CuII) among the three collimators was reduced to less than 5%. This adjustment significantly improved both the spatial and temporal uniformity of the plasma. The HiPIMS-Cu coating on a flexible PET polymer web was systematically evaluated at 20 sampling points: two points distributed across the 660 mm web width at 500 mm intervals, and ten points along the 500 m web length at 50 m intervals. Results revealed that variations in both film thickness and sheet resistance remained within 10% across all sampling points, confirming excellent film uniformity and quality. Furthermore, for HiPIMS-Cu coatings with thicknesses below 50 nm, the sheet resistance was consistently less than 2 Ω/□. These findings demonstrate that the use of active feedback control in R2R HiPIMS coaters substantially enhances long-term stability, enabling high-quality, large-scale mass production of coatings with uniform properties and reliable performance.