A Combined Spin Coating and Lift-Off Process (CSLOP) to Realize Thick Silver Microstructures with a High Aspect Ratio for IoT Applications

This paper presents a new manufacturing technology, i.e., combined spin coating and lift-off process (CSLOP), for the fabrication of Ag interconnects and microstructures such as interconnect lines, interdigitated capacitors and spiral inductors with a high aspect ratio of thickness vs. width. For the interconnect fabrication using the thin film CSLOP, Ag lines with a width range from 10 to 100 can be realized with an electrical resistivity of 2.36Omega\cdot \cm, only 1.48 × higher than that of bulk silver (1.59Omega\cdot \cm), which is the lowest resistive Ag line ever reported. For high performance on-chip flexible passive fabrication using the thick film CSLOP, the interdigitated capacitors with an electrode thickness of 70 can exhibit a capacitance of 0.502pF@10 kHz and the 5-turn, 70 thick spiral inductor can have high Q performance with a highest inductance density up to 9.7 nH/mm2. Because the process scheme can be applied using other metal/metal oxide nanoparticles, the CSLOP can facilitate the realization of highly sensitive sensors and excellent heterogeneous integration for IOT applications.