| AVS 61st International Symposium & Exhibition | |
| In-Situ Spectroscopy and Microscopy Focus Topic | Thursday Sessions |
| Session IS-ThP |
| Session: | In-Situ Spectroscopy and Microscopy Poster Session |
| Presenter: | SeungYoub Lee, Sungkyunkwan University, Republic of Korea |
| Authors: | S.Y. Lee, Sungkyunkwan University, Republic of Korea C. Jeon, Korea Basic Science Institute, Republic of Korea Y. Kim, Sungkyunkwan University, Republic of Korea J. Lee, Korea Basic Science Institute, Republic of Korea C.-Y. Park, Sungkyunkwan University, Republic of Korea |
| Correspondent: | Click to Email |
Atomic layer deposition (ALD) can be regarded as a special variation of the chemical vapor deposition method for reducing film thickness. ALD is based on sequential self-limiting reactions from the gas phase to produce thin films and over-layers in the nanometer scale with perfect conformality and process controllability. These characteristics make ALD an important film deposition technique for nanoelectronics. Tantalum pentoxide (Ta2O5) has a number of applications in optics and electronics due to its superior properties, such as thermal and chemical stability, high refractive index (>2.0), low absorption in near-UV to IR regions, and high-k. In particular, the dielectric constant of amorphous Ta2O5 is typically close to 25. Accordingly, Ta2O5 has been extensively studied in various electronics such as metal oxide semiconductor field-effect transistors (FET), organic FET, dynamic random access memories (RAM), resistance RAM, etc.
In this experiment, the variations of chemical and interfacial state during the growth of Ta2O5 films on the Si substrate by ALD was investigated using in-situ synchrotron radiation photoemission spectroscopy. A newly synthesized liquid precursor Ta(NtBu)(dmamp)2Me was used as the metal precursor, with Ar as a purging gas and H2O as the oxidant source. The core-level spectra of Si 2p, Ta 4f, and O 1s revealed that Ta suboxide and Si dioxide were formed at the initial stages of Ta2O5 growth. However, the Ta suboxide states almost disappeared as the ALD cycles progressed. Consequently, the Ta5+ state, which corresponds with the stoichiometric Ta2O5, only appeared after 4.0 cycles. Additionally, tantalum silicide was not detected at the interfacial states between Ta2O5 and Si. The measured valence band offset value between Ta2O5 and the Si substrate was 3.08 eV after 2.5 cycles.