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P‐166: Microstructural Characterization of the Interface between IZO and Mo/Al/Mo Metal Line Used in TFT‐LCDs
Author(s) -
Choi Sunglak,
Hwang SeongYong,
Oh Weon Sik,
Kim Miyang
Publication year - 2005
Publication title -
sid symposium digest of technical papers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.351
H-Index - 44
eISSN - 2168-0159
pISSN - 0097-966X
DOI - 10.1889/1.2036439
Subject(s) - materials science , amorphous solid , layer (electronics) , annealing (glass) , passivation , oxide , alloy , diffusion barrier , metal , hillock , barrier layer , metallurgy , composite material , crystallography , chemistry
Mo layer is used as a protective layer of Al metal line causing problems such as hillock and oxidation in TFT‐LCDs. When the insulating SiNx and passivation layer is etched to form a contact hole in Mo/Al/Mo trilayered metal line, the upper Mo layer is also removed due to the lack of selectivity of the dry etching process. As a result, IZO layer appear to contact to Al directly, possibly resulting in the formation of Al 2 O 3 increasing the contact resistivity. However, detailed investigation by TEM revealed that there are two amorphous layers, inner and outer layers, preventing the direct contact of IZO to Al layer. The inner layer was enriched with Mo, while the outer layer was enriched with Al and oxygen. Oxygen concentration was considerably reduced in front of the inner layer, indicating the Mo‐rich inner layer as a barrier layer against oxygen diffusion. On the other hand, Al concentration was still higher and decreasing continuously across the inner layer, exhibiting fast Al diffusion through the inner layer. It was shown that Al‐Mo alloy is able to form an amorphous phase at the interface during deposition because of large difference in melting point between Al and Mo. Based on the observed details, the interfacial amorphous layers are considered to produce thermodynamically stable phase, oxide and intermetallic compound, upon further annealing.