Wafer-scale integration of in-situ grown carbon nanotube membranes: a platform to study electrical properties

H. Le Poche, H. Guerin, A. Fournier, R. Ramos, M. Fayolle, M. Delaunay, J. Dijon, A.M. Ionescu
CEA LITEN, FR

Keywords: carbon nanotubes, membranes, in-situ growth, wafer-scale integration, electronic devices, electrical characterizations

Summary:

Dense arrays of horizontal carbon nanotubes (CNTs) connected between two metallic electrodes and either supported on a silicon dioxide layer or suspended above a third gate electrode constitute a basic building block to achieve CNT-based electronic devices such as sensors, interconnect lines or micro-electromechanical systems. Despite the recognized potential of CNTs, their adoption as alternative materials is postponed mainly due to integration issues at wafer-scale. A reliable integration scheme, based on in-situ CNT growth by chemical vapor deposition (CVD), totally compatible with full wafer processing was previously proposed by our team to manufacture multi-criteria resistive and resonating gas sensors. Resistive sensors were fabricated via the successful integration of supported, dense horizontal few-walled CNT membranes on 100 mm wafers. Here, the suspension of the membranes is experimentally demonstrated by etching the under-lying silicon dioxide in a buffered HF solution followed by a critical point drying. Moreover, the elaboration of a huge number of similar CNT membranes at the wafer-scale constitutes a real asset to study and optimize the impact of post-growth processes on the CNT electrical performances: top metallization, encapsulation and suspension processes are investigated as critical steps for CNT-based device fabrication.