High-temperature adaptive through-silicon via with pyrolyzed carbon via-sealing plates for packaging 3D carbon nanostructure-based devices fabricated using C-MEMS

Abstract

Through-silicon via (TSV) is a key packaging technology that facilitates the 2.5D/3D integration of microelectromechanical system (MEMS) devices. Among various MEMS technologies, C-MEMS enables micro/nanoscale 3D carbon structure manufacturing using high-temperature (600-1200 degrees C) pyrolysis. These hightemperature conditions limit the application of conventional TSV technologies to C-MEMS devices. This study presents a novel TSV with carbon via-sealing plates that are adaptable to C-MEMS device packaging. Via holes are drilled before integrating the MEMS device to protect the delicate micro/nanoscale structures. Moreover, the topside via inlet is sealed with a thin conductive pyrolyzed carbon plate to prevent the contamination of the via interior during the C-MEMS process and ensure an electrical connection between the devices and the vias. After integrating the C-MEMS devices, TSV fabrication is completed by coating the via inside with a metal layer from the wafer's bottom side, achieving a conductance per unit area of approximately 327 S/mm2 (via diameter = 33 mu m, length = 100 mu m). The applicability of the proposed wafer-level TSV technology to C-MEMS devices is then verified through the implementation of a suspended carbon nanowire-based gas sensor integrated with the developed TSV, which exhibits excellent signal transmission. Furthermore, the proposed TSV packaging technology can be applied to various micro/nanofabrication technologies because of its high-temperature/wetprocess compatibility and cost-effective fabrication.