A transfer-free wafer-scale CVD graphene fabrication process for MEMS/NEMS sensors

Abstract

In this paper we report a novel transfer-free graphene fabrication process, which does not damage the graphene layer. Uniform graphene layers on 4" silicon wafers were deposited by chemical vapor deposition using the CMOS compatible Mo catalyst. Removal of the Mo layer after graphene deposition results in a transfer-free and controlled placement of the graphene on the underlying SiO 2 . Moreover, pre-patterning the Mo layer allows customizable graphene geometries to be directly obtained, something that has never been achieved before. This process is extremely suitable for the large-scale fabrication of MEMS/NEMS sensors, especially those benefitting from specific properties of graphene, such as gas sensing.

Wafer-scale transfer-free process of multi-layered graphene grown by chemical vapor deposition

“…The average ratio I(D)/I(G) indicates the presence of some defects in the material [43,46,47,49,50]. In this letter, we mostly showed the power of the transfer-free process.…”

“…The growth and target substrate are the same, thus avoiding any transfer from the two substrates, reducing the possibility to degrade the film and enabling the direct integration of graphene-based devices at large scale [42]. This outcome represents a remarkable step forward compared to the method we reported in our previous works [43][44][45][46]. In those papers, we dealt with areas of patterned MLG of hundreds μm 2 which we fabricated using several steps in the lithographic process.…”

Low Temperature CVD Grown Graphene for Highly Selective Gas Sensors Working under Ambient Conditions

“…A thin film of Mo (50 nm) was sputtered from a pure (99.95%) Mo target. Afterwards, dry etching was used to pattern the Mo layer, as described in our previous work [5]. The graphene growth on the patterned Mo catalyst was carried out in an AIXTRON BlackMagic Pro at 850 °C, using Ar/H2/CH4 as feedstock at a pressure of 25 mbar.…”

“…The graphene growth on the patterned Mo catalyst was carried out in an AIXTRON BlackMagic Pro at 850 °C, using Ar/H2/CH4 as feedstock at a pressure of 25 mbar. The Mo catalyst was then etched away following the transfer-free process (TFP) we developed [5] and the graphene film laid on the SiO2. Evaporated Cr/Au (10/100 nm) electrical contacts were defined on the top of graphene film using a lift-off process.…”

“…Here, we present the performances of the gas chemi-resistors based on graphene fabricated through a process specifically developed to lower the growth temperature down to 850 °C. This value is significantly much lower than the 980 °C usually adopted as graphene growth temperature [2,4,5]. The choice to reduce the growth temperature is motivated by the fact that a lower growth temperature can reduce the energy consumption during the graphene growth and facilitate large scale production of these gas sensors.…”