In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2020-02, No. 23 ( 2020-11-23), p. 1663-1663
Kurzfassung:
Copper is widely used in the semiconductor industry as interconnects due to its low resistivity, high resistance to electromigration, low temperature coefficient of resistance, and good thermal stability (1). As advanced nanoelectronics has moved towards the sub-5 nm node technology and beyond, the back-end of line interconnects process is scaled down to smaller pitch sizes with a lot of challenges (2,3). Recently, area-selective atomic layer deposition (AS-ALD) by locally passivating the surface has garnered attention as it can lead to a paradigm shift from today’s top-down VLSI fabrication by not only reducing the number of processing steps but also by alleviating key challenges associated with lithography and layer alignment at the sub-5 nm node (4). However, there are still several challenging factors to implement them in the process node successfully. Despite the enormous scientific effort in recent years, lack of surface science during cleaning and passivation of Cu surfaces impede the development of AS-ALD. Specifically, the initial surface condition of Cu films can affect not only a cleaning surface (i.e., adventitious contaminants and Cu x O) but also further passivation process using a self-assembled monolayer (SAMs). Recently, the reduction of the Cu surface using vapor-phase N 2 H 4 has been reported due to its higher reduction capability (4,5). Herein, the effect of the initial surface condition of Cu samples on both cleaning and passivation of the surfaces was investigated. Electroplated Cu films were pretreated using anhydrous N 2 H 4 for vapor phase surface cleaning. Reflectance absorption infrared spectroscopy (RAIRS) with ALD capability was employed to elucidate the surface chemistry. During surface cleaning, N 2 H 4 reduces the surface oxide (Cu 2 O) to metallic copper as well as remove adventitious surface contaminants (e.g., –CH x , –CO 3 , and –OH). In the case of cleaning with CH 3 COOH, the Cu surface reduces the surface oxide (Cu 2 O) to metallic copper, importantly the copper acetate which might be the intermediate material was formed after cleaning. After pretreatment, each Cu sample was immersed into 1 mM octadecanethiols (ODTs) in ethanol for 20 hours, then ALD of AlO x using TMA and H 2 O was performed at 120 o C. The N 2 H 4 -treated Cu sample shows better physical and chemical stability during ALD process, resulting in good selectivity compared to the SAMs on the as-is Cu. The detailed experimental results will be presented. This work is supported by Rasirc Inc. by providing the anhydrous N 2 H 4 . This work was also partly supported by the Fostering Global Talents for Innovative Growth Program (No. P0008750) through KIAT and MOTIE. J. Ahn and J. Kim also acknowledge partial financial supports by Brain Pool Program through National Research Foundation by the Ministry of Science and ICT in Korea (Grant #: 2019H1D3A2A01101691). R. P. Chaukulkar, N. F. W. Thissen, V. R. Rai, and S. Agarwal, J. Vac. Sci. Technol. A , 32 , 01A108 (2014). L. F. Pena, J. F. Veyan, M. A. Todd, A. Derecskei-Kovacs, and Y. J. Chabal, ACS Appl. Mater. Interfaces , 10 , 38610–38620 (2018). M. He et al., J. Electrochem. Soc. , 160 , D3040–D3044 (2013). D. M. Littrell, D. H. Bowers, and B. J. Tatarchuk, J. Chem. Soc. Faraday Trans. 1 Phys. Chem. Condens. Phases , 83 , 3271–3282 (1987). S. M. Hwang et al., ECS Trans. , 92 , 265–271 (2019). Figure 1
Materialart:
Online-Ressource
ISSN:
2151-2043
DOI:
10.1149/MA2020-02231663mtgabs
Sprache:
Unbekannt
Verlag:
The Electrochemical Society
Publikationsdatum:
2020
ZDB Id:
2438749-6
