Growth of High Quality Cobalt Metal Thin Film by Low Temperature UV-Assisted Atomic Layer Deposition

ZhengYong Liang^1*, Yung-Chang Lin², Chao-Hui Yeh¹, Jui-Hsiung Liu³, Po-Wen Chiu^1,4

¹Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
²National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
³Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
⁴Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:ZhengYong Liang, email:kenneth942149@hotmail.com

Atomic layer deposition is a potential process for the deposition of various thin films such as diffusion barriers, liner materials and seed layers, which are required for state-of-the-art interconnects. In this study, Co thin film were deposited by UV-assisted atomic layer deposition using Co(CO)3NO as the Co precursor. The deposited Co films possess decent crystallinity and flatness. The UV-assisted process not only lower the deposition temperature, but also enhance the surface chemisorption, leading to an appreciable increase of deposition rate up to 5.1 Å/ cycle. The impurity contents were also minimized when the Co films deposited by remote plasma UV-ALD with hydrogen plasma in the process temperature range of 190-200 °C. From the XPS analysis, the cobalt and oxygen contents were about 98.2% and 1%, respectively, while the carbon and nitrogen residuals amount to less than 1%. In the flatness analysis by AFM, the RMS of the film deposited at 200 °C was observed to be 1.1 nm, while the film deposited at 180 °C has an RMS of 0.6 nm. After annealing at 350 °C for 15 min, the resistivity of the Co film with thickness of 55 nm can reach 1.0E-5 Ωcm.

Keywords: atomic layer deposition, cobalt, thin film, cobalt tricarbonyl nitrosyl, UV