Thermal Stability of Copper–Nickel and Copper–Nickel Silicide Contacts for Crystalline Silicon

Journal Article · 16 May 2018 · ACS Applied Energy Materials

DOI: https://doi.org/10.1021/acsaem.8b00488 · OSTI ID:1479870

Nemeth, William M. ^[1]; Perkins, Craig ^[1]; Young, David L. ^[1]; Stradins, Paul ^[1]; Marshall, Alexander ^[2]; Florent, Karine ^[2]; Kurinec, Santosh K. ^[2]; Agarwal, Sumit ^[3]; Kale, Abhijit ^[3]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
2. Rochester Inst. of Technology, NY (United States)
3. Colorado School of Mines, Golden, CO (United States)

Copper is a low-cost, low-damage alternative to Ag paste for front-side metallization of crystalline Si (c-Si) solar cells, but requires conductive diffusion barriers like Ni or NiSi. Thermal stability of these barriers during postmetallization anneal is critical for performance. In this study, we address the structural and chemical stability of Cu contacts with both Ni and NiSi barrier layers, identifying interfacial reactions responsible for their degradation. Superior thermal and chemical stability of single-phase NiSi barrier as compared to Ni is made evident by XRD, Auger, and Raman spectroscopies. Moreover, the commonly used Cu-Ni-Si contact stack does not convert to more stable Cu-NiSi-Si stack upon thermal treatment. Instead, Cu readily alloys with the Ni layer and reacts with the underlying c-Si to form Cu₃Si, with no evidence for the formation of NixSi phases. Also, even the superior NiSi barrier slowly dissolves into Cu at elevated temperatures.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1479870
• Report Number(s): NREL/JA--5900-71509
• Journal Information: ACS Applied Energy Materials, Journal Name: ACS Applied Energy Materials Journal Issue: 6 Vol. 1; ISSN 2574-0962
• Publisher: American Chemical Society (ACS)Copyright Statement
• Country of Publication: United States
• Language: English