|AVS 57th International Symposium & Exhibition|
|Thin Film||Wednesday Sessions|
|Session:||High K Dielectrics for Si Electronics|
|Presenter:||J.C. Lee, Samsung Advanced Institute of Technology, Korea|
|Authors:||J.C. Lee, Samsung Advanced Institute of Technology, Korea
E.H. Lee, Samsung Advanced Institute of Technology, Korea
J.G. Chung, Samsung Advanced Institute of Technology, Korea
B. Anass, Samsung Advanced Institute of Technology, Korea
J.H. Lee, Samsung Advanced Institute of Technology, Korea
J.S. Park, Samsung Advanced Institute of Technology, Korea
M.K. Ryu, Samsung Advanced Institute of Technology, Korea
|Correspondent:||Click to Email|
ZnO based oxide semiconductor is a promising material for thin film transistor which has transparent, high electric mobility, and the advantage of low temperature process. Several kinds of ZnO based oxide semiconductors (InZnO, GaInZnO, HfInZnO, etc.) have been adapted to the active material of thin film transistor. However most of ZnO based oxide semiconductors have very sensitive property to ambient environment. It is essential to prevent the penetration of moisture into ZnO based oxide thin film transistor (TFT). In the purpose of preventing moisture penetration and/or protecting damage from TFT processes, SiNx or SiO2 passivation layer is used frequently.
In this study, we investigated the interface reactions between amorphous HfInZnO (Hf:In:Zn= 10:35:55, 40nm thickness) oxide semiconductor active layer and the passivation layer of SiNx or SiO2 (20 nm thickness). TEM, XPS and SIMS were used to investigate the interface reactions such as atomic diffusion, reduction of HfInZnO, chemical state, microstructure.
According to experimental results, a SiO2 phase and Indium metallic state were observed at the interface between SiNx and HfInZnO active layer. On the other hand, there was not observed Indium metallic state at the interfaces between SiO2 and HaInZnO layers. In the case of SiNx passivation, it is considered that some Si took oxygen from Indium oxide in HfInZnO and oxidized to SiO2. And some of Indium oxide reduced to metallic Indium at the interface. Indium diffusions from HfInZnO layers into passivation layers were observed at the both of SiNx and SiO2 samples. In the case of SiNx passivation, it was a little bit higher diffusion than that of SiO2 passivation. The low binding energy shift was observed at the Zn2p XPS spectra at the both samples. However, there was no distinct difference at the Hf4d spectra.
If there is metallic Indium between passivation and HfInZnO active layers, the metallic Indium may influence the conductance of active layer. The threshold voltage (Vth) shift of thin film transistor (TFT) could be affected by the change of conductance of active layer.
We observed that the Vth negative shift of the TFT used SiNx passivation was higher than that of SiO2 passivation. It may be due to the existence of metallic Indium at the interface.
In this report, it will be described the relationships between interface reactions and the property of HfInZnO oxide TFT in detail.