Hiroyuki Okuno

Study of adhesion and chemical bonds in the reaction layer formed at Cu-Mn interconnection/SiO2 interface

In this study, adhesion of the Cu/Cu-Mn stacked interconnections to glass (SiO2) substrates was evaluated and the results were correlated with a detailed analysis of the reaction layer between the Cu-Mn and the chemical vapour deposited SiO2. When the Mn concentrations were varied, an abrupt change in the adhesion properties was observed; the practical adhesion properties were obtained in the Cu/Cu-Mn interconnections with Mn concentrations at 8% and higher. To clarify the chemical nature and the microstructure of the reaction layer at the interface between the Cu-x Mn (x = 4, 10 at. %) and the SiO2 layers was analysed using angle-resolved x-ray photoelectron spectroscopy and transmission electron microscope-electron energy loss spectroscopy. These observations indicated that the cross-sectional structure along the reaction layer of the Cu–10 at. % Mn sample can be divided into two regions: in the high Mn region, the Mn-Si complex oxide and the SiO2 mixture phase are preferable due to a decrease in the ox...

Electrical Conduction across the Direct Contact between Indium–Tin Oxide and Al–Ni Alloy Layers

The electrical conduction across direct contacts between indium–tin oxide (ITO) and the newly developed Al–Ni alloys, used for amorphous silicon thin-film transistors (a-Si TFTs) in liquid crystal displays (LCDs), has been studied. The ITO/Al–Ni alloy interfaces were examined by both electrical measurements using nanoprobes and cross-sectional transmission electron microscopy (XTEM). It was found that the major conduction path across the ITO/Al–Ni alloy interface was via Al3Ni precipitates, and that the resistivity of the ITO/Al–Ni alloy contact strongly depended on the conditions of the Al–Ni alloy surface. It was thus concluded that the generation of non-oxidized Al3Ni precipitates after photoresist stripping is important for high-quality direct contacts. The present results on the Al–Ni alloy compositions and ITO/Al–Ni alloy interfaces have already been considered in the actual production of a-Si TFTs for LCDs.

Low driving voltage indium–tin oxide/Al–Ni–Cu–La anode electrodes for top-emission organic light-emitting diodes

We have developed indium–tin oxide (ITO)/Al–Ni–Cu–La anode electrodes for cost-effective large top-emission organic light-emitting diode (OLED) displays. By combining alkaline cleaning with thermal annealing, the driving voltage of the OLED devices containing Al–Ni–Cu–La thin films was effectively reduced, becoming comparable to that for conventional Ag alloy thin films. Cross-sectional transmission electron microscopy (XTEM) observation revealed that the grains in the Al matrix and the precipitates on the Al–Ni–Cu–La surface were small, resulting in a low driving voltage and a high optical reflectivity. The Al–Ni–Cu–La thin films overcome the oxidation issues that cause an increase in contact resistance due to the formation of AlO x between the Al alloy and the ITO thin films, and could replace conventional anode electrodes having an ITO/Ag/ITO structure.