Study of nickel silicide as a copper diffusion barrier in monocrystalline silicon solar cells

Kale, Abhijit S.; Beese, Emily; Saenz, Theresa E.; Warren, Emily L.; Nemeth, William; Young, David L.; Marshall, Alexander; Florent, Karine; Kurinec, Santosh; Agarwal, Sumit; Stradins, Pauls

doi:10.1109/pvsc.2016.7750190

Cited by 6 publications

(11 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The intermediate nickel silicide layer reduces the ohmic contact resistance and enhances the extraction of the photo generated carriers. The Ni–Si equilibrium phase diagram predicts the formation of six stable intermetallic compounds such as Ni 3 Si, Ni 31 Si 12 , Ni 2 Si, Ni 3 Si 2 , NiSi, and NiSi 2 . The formation of the phase depends on the amount of Ni and Si available for the reactions, the annealing temperature, and the impurities present in the nickel seed layer.…”

Section: Resultssupporting

confidence: 91%

“…The Ni−Si equilibrium phase diagram predicts the formation of six stable intermetallic compounds such as Ni 3 Si, Ni 31 Si 12 , Ni 2 Si, Ni 3 Si 2 , NiSi, and NiSi 2 . 33 The formation of the phase depends on the amount of Ni and Si available for the reactions, the annealing temperature, and the impurities present in the nickel seed layer. Among the intermetallic Ni− Si compounds, NiSi has a resistivity in the range of 5−18 μΩ cm 2 .…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Realization of Micropatterned, Narrow Line-Width Ni–Cu–Sn Front Contact Grid Pattern Using Maskless Direct-Write Lithography for Industrial Silicon Solar Cells

Aleem

Vishnuraj

Krishnan

et al. 2021

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

An industry-ready strategic process for the fabrication of cost-effective, micropatterned Ni–Cu–Sn front contact metallization has been demonstrated using maskless direct-write lithography, which could effectively reduce the shadow loss and thereby enhance the efficiency of silicon solar cells by increasing the active area. This investigation also addresses the challenging issues in Ni–Cu–Sn metallization, such as adhesion of the seed layer, low-ohmic contact formation, background plating, and cell processing complications. An eco-friendly aluminum paste with a sheet resistivity of 35 mΩ/cm2 has been developed to fabricate the rear contact on silicon solar cells. A front contact metallization grid with an optimal narrow finger width of 20 μm with an interfinger spacing of 1000 μm has been micropatterned using maskless direct-write lithography for the metallization process. To improve the electrical and mechanical properties of the nickel seed layer, the thickness was optimized as ∼100 nm with a contact resistivity of 6.87 μΩ cm2, which exhibited an adhesion strength of 2.5 N/mm. A low ohmic contact intermediate silicide layer has been created at the Ni–Si interface by the rapid thermal annealing process at 420 °C for 90 s with subsequent copper and tin electroplating to form the Ni–Cu–Sn contacts. An average cell efficiency of 18.5% is achieved for silicon solar cells with a micropatterned Ni–Cu–Sn-based narrow line-width front contact grid design, which could exhibit an ∼1% cell efficiency enhancement as compared to commercial Ag screen-printed solar cells. An ∼6% improvement in cell performance is achieved by reducing the shadow loss with the Ni–Cu–Sn-based front contact metallization as compared to the commercial Ag screen-printed metallization.

show abstract

Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Realization of Micropatterned, Narrow Line-Width Ni–Cu–Sn Front Contact Grid Pattern Using Maskless Direct-Write Lithography for Industrial Silicon Solar Cells

Aleem

Vishnuraj

Krishnan

et al. 2021

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

show abstract

“…As such behavior was not observed with Cu-joining, Ni is expected to play an important part in this electromigration process. It is carried by the current from the electrode to the sample, but it acts as a diffusion barrier to Cu when the diffusion happens in the opposite direction of the current flow 55 . In fact, Ni, but also metallic silicide materials (Ni-Si in this case) are known to be good barriers to Cu diffusion 53,[56][57] Annealing experiments were carried out at 450°C during one week for Cu joining to study the thermal stability and the development of .…”

Section: Discussionmentioning

confidence: 99%

“…It is carried by the current from the electrode to the sample, but it acts as a diffusion barrier to Cu when the diffusion happens in the opposite direction of the current flow. 55 In fact, Ni, but also metallic silicide materials (Ni−Si in this case) are known to be good barriers to Cu diffusion. 53,56,57 The difference in joining temperatures with Cu and Ni 45 Cu 55 (600 °C and 550 °C, respectively) is another possible explanation that cannot be excluded.…”

Section: Discussionmentioning

confidence: 99%

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes

Ayachi

Hernández

Pham

et al. 2019

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Magnesium silicides can be used for thermoelectric energy conversion, as high values of figure of merit zT were obtained for n-type (1.4 at 500 °C) and p-type (0.55 at 350 °C) materials. This, however, needs to be complemented by low resistive and stable contacting to ensure long-term thermogenerator operation and minimize losses. In this study, we selected Cu and Ni 45 Cu 55 as contacting electrodes for their high electrical conductivity, similar coefficient of thermal expansion (CTE) and good adhesion to Mg 2 (Si,Sn). Both electrodes were joined to Mg 2 Si 0.3 Sn 0.7 pellets by hot pressing in a current-assisted press. Microstructural changes near the interface were analyzed using SEM/EDX analysis, and the specific electrical contact resistance r c was estimated using a travelling potential probe combined with local Seebeck scanning. Good contacting was observed with both electrode materials. Results show low r c with Cu, suitable for application, for both n-type and p-type silicides (< 10 µΩ•cm 2 ), with the occurrence of wide, highly conductive diffusion regions. Ni 45 Cu 55 joining also showed relatively low r c values (~ 30 µΩcm 2 ) for n-and p-type, but had a less inhomogeneous reaction layer. We also performed annealing experiments with Cu-joined samples at 450 °C for one week to investigate the evolution of the contact regions under working temperatures. r c values increased (up to ~ 100 µΩcm 2 ) for annealed n-type samples, but remained low (< 10 µΩcm 2 ) for p-type. Therefore, Cu is a good contacting solution for p-type Mg 2 (Si,Sn), and a potential one for n-type if the diffusion causing contact property degradation can be prevented.

show abstract

“…27 These studies involve the use of solutionbased Ni plating processes where certain impurities can be incorporated, which can lead to erroneous results. 28,29 We further speculate that the above-mentioned contradictory results have been obtained most likely due to the test devices being subjected to high-temperature thermal stress conditions for accelerated reliability determination, which affects film integrity. However, high-temperature thermal processing steps may be required in actual cell manufacturing, and this can be a serious reliability issue if these steps affect the integrity of Cu/ Ni-based contacts.…”

Section: Introductionmentioning

confidence: 99%

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

Kale

Nemeth

Perkins

et al. 2018

ACS Appl. Energy Mater.

Self Cite

View full text Add to dashboard Cite

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 Cu 3 Si, with no evidence for the formation of Ni x Si phases. Also, even the superior NiSi barrier slowly dissolves into Cu at elevated temperatures.

show abstract

Study of nickel silicide as a copper diffusion barrier in monocrystalline silicon solar cells

Abstract: The information contained in this poster is subject to a government license.

Cited by 6 publications

References 9 publications

Realization of Micropatterned, Narrow Line-Width Ni–Cu–Sn Front Contact Grid Pattern Using Maskless Direct-Write Lithography for Industrial Silicon Solar Cells

Realization of Micropatterned, Narrow Line-Width Ni–Cu–Sn Front Contact Grid Pattern Using Maskless Direct-Write Lithography for Industrial Silicon Solar Cells

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes

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

Contact Info

Product

Resources

About

Study of nickel silicide as a copper diffusion barrier in monocrystalline silicon solar cells

Abstract: The information contained in this poster is subject to a government license.

Cited by 6 publications

References 9 publications

Realization of Micropatterned, Narrow Line-Width Ni–Cu–Sn Front Contact Grid Pattern Using Maskless Direct-Write Lithography for Industrial Silicon Solar Cells

Realization of Micropatterned, Narrow Line-Width Ni–Cu–Sn Front Contact Grid Pattern Using Maskless Direct-Write Lithography for Industrial Silicon Solar Cells

Developing Contacting Solutions for Mg2Si1–xSnx-Based Thermoelectric Generators: Cu and Ni45Cu55 as Potential Contacting Electrodes

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

Contact Info

Product

Resources

About

Developing Contacting Solutions for Mg₂Si_1–xSn_x-Based Thermoelectric Generators: Cu and Ni₄₅Cu₅₅ as Potential Contacting Electrodes