Low-Temperature Deposition and Material Characterization of Hydrogenated Graphene Oxide Thin Films on Copper...

Graphene-derived films such as graphene oxide (GO) and hydrogenated graphene oxide (HGO) are of interest for energy storage, catalysis, sensing applications, and as low-thermal-budget carbon films; here, we focus on their low-temperature synthesis and material characterization. However, the in-use chemical vapor deposition (CVD) process for HGO requires high-temperature processing (above 1000 °C or 1273 K), which is unsuitable for back-end-of-line (BEOL) Complementary Metal-Oxide-Semiconductor (CMOS) process integration. In this work, we report on an efficient low-temperature (773 K) method and detailed material characterization of synthesizing HGO on a copper substrate using a 2.45 GHz Electron Cyclotron Resonance (ECR) Plasma Enhanced Chemical Vapor Deposition (PECVD) system. At first, we employ a Quadrupole-based Residual Gas Analyzer (QRGA) for analysis of active chemical species during the gaseous-phase reaction at 300 K, 573 K, and 773 K to optimize growth conditions. The findings indicate that at 773 K, the presence of ECR plasma in conjunction with methane as the precursor gas is consistent with the formation of hydrogenated, oxygen-containing graphitic films. Raman spectroscopy further reveals characteristic D, G, and 2D bands at approximately 1343, 1577, and 2843 cm^-1, respectively. The full survey scan of X-ray photoelectron spectroscopy (XPS) shows prominent signals for C 1s and O 1s core levels, where the deconvolution of the C 1s spectra indicates CC (284.2 eV), sp³-type carbon (285.3 eV), C-O (286.2 eV), and CO (287.5 eV) bonding states, while the O 1s spectra confirm CO (530.8 eV) and C-O (532.6 eV) bonds. Finally, we investigate the surface morphology using scanning electron microscopy and Atomic Force Microscopy (AFM) imaging.