Moisture barrier properties of single-layer graphene deposited on Cu films for Cu metallization

Abstract

The moisture barrier properties of large-grain single-layer graphene (SLG) deposited on a Cu(111)/sapphire substrate are demonstrated by comparing with the bare Cu(111) surface under an accelerated degradation test (ADT) at 85 °C and 85% relative humidity (RH) for various durations. The change in surface color and the formation of Cu oxide are investigated by optical microscopy (OM) and X-ray photoelectron spectroscopy (XPS), respectively. First-principle simulation is performed to understand the mechanisms underlying the barrier properties of SLG against O diffusion. The correlation between Cu oxide thickness and SLG quality are also analyzed by spectroscopic ellipsometry (SE) measured on a non-uniform SLG film. SLG with large grains shows high performance in preventing the Cu oxidation due to moisture during ADT.

A novel graphene barrier against moisture by multiple stacking large-grain graphene

“…4b−d). The color change of SLG-coated Cu surface was qualitatively similar to the previous report 20 , but the dark color areas were relatively larger in this study probably due to the higher density of defects. In contrast, the DLG- and TLG-coated surfaces exhibited large shiny areas after THS testing.…”

“…Regarding the previous report of moisture barrier properties of SLG-coated Cu surface 20 , we reproduce this experiment again, and then found that some areas of Cu surface were oxidized after 100 h of THS testing, as shown in the relative O/Cu atomic concentration ratios investigated by XPS (Fig. 1).…”

“…We reported that CVD-grown single-layer graphene (SLG) can serve as an efficient impermeable film to prevent the diffusion of moisture. However, some areas of the Cu surface were oxidized 20 . The oxidized areas were speculated as the grain-boundaries or defective areas in the previous work.…”

Advances in multilayer graphene processes for metallization and high-frequency devices

“…3. 31,32) Figure 3 shows the surface photos from an optical microscope with a scale bar of 20 μm after temperature and humidity stress (THS) tests at 85 °C/85 % relative humidity for 200 h, the X-ray photoemission spectroscopy (XPS) Cu 2p spectra before and after the THS tests, and the schematic structures for (a) without a graphene cap (the schematic structure is not shown), (b) with SLG, (c) with BLG and (d) with triple-layer graphene (TLG), respectively. In the case of Cu surface without any cap, the surface color became uniformly dark, and the Cu + Cu 2 O peak, which indicates that it is metallic and a lower oxidation state of Cu, decreased and the CuO peak, which indicates a higher oxidation state of Cu, increased in the XPS Cu 2p spectra after the THS, as shown in Fig.…”

Structural analysis of graphene-capped copper by spectroscopic ellipsometry for humidity reliability assessment

“…15) Gr cap has other advantages, such as higher heat conduction to lower the interconnect temperature and higher humidity reliability. 12,17,18) Moreover, it was reported that Gr cap can reduce the resistance of Ru film. 19) To realize a manufacturing method that guarantees high reliability, it is essential to evaluate the quality and thickness of Gr film capped on the Cu surface.…”