Nucleation and diffusion during growth of ternary Co1−xNixSi2 thin films studied by complementary techniques in <i>real time</i>

Smeets, Dries; Demeulemeester, Jelle; Keyser, K. De; Deduytsche, Davy; Detavernier, Christophe; Comrie, C.M.; Theron, C.C.; Lavoie, C.; Vantomme, André

doi:10.1063/1.3013449

Cited by 14 publications

(11 citation statements)

References 38 publications

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“…NiSi 2 , is the enhanced formation of the disilicide Co 1-x Ni x Si 2 from a CoSi/NiSi mixture and the delayed nucleation of NiSi 2 from a Ni 1-x Pt x Si solid solution. [5][6][7] The presence of the isomorphous phases NiSi 2 and CoSi 2 on the one hand and NiSi and PtSi on the other hand is crucial to allow solid solubility and, consequently, to affect the sign of DS. As NiSi and PtSi, PdSi also shares the same crystal structure and alloying Ni with Pd has been shown to delay NiSi 2 nucleation.…”

Section: Introductionmentioning

confidence: 99%

On the nucleation of PdSi and NiSi2 during the ternary Ni(Pd)/Si(100) reaction

Schrauwen

Demeulemeester

Kumar

et al. 2013

Journal of Applied Physics

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During the solid phase reaction of a Ni(Pd) alloy with Si(100), phase separation of binary Ni-and Pd-silicides occurs. The PdSi monosilicide nucleates at temperatures significantly below the widely accepted nucleation temperature of the binary system. The decrease in nucleation temperature originates from the presence of the isomorphous NiSi, lowering the interface energy for PdSi nucleation. Despite the mutual solubility of NiSi and PdSi, the two binaries coexist in a temperature window of 100 C. Only above 700 C a Ni 1-x Pd x Si solid solution is formed, which in turn postpones the NiSi 2 formation to a higher temperature due to entropy of mixing. Our findings highlight the overall importance of the interface energy for nucleation in ternary systems. V C 2013 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 99%

On the nucleation of PdSi and NiSi2 during the ternary Ni(Pd)/Si(100) reaction

Schrauwen

Demeulemeester

Kumar

et al. 2013

Journal of Applied Physics

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“…The leading side of silicidation shows a composition of Ni 50 Co 10 Si 40 , a metal rich composition Me 3 Si 2 , similar to the results in Figure 3. In addition, the trailing side has a composition of Ni 40 Si 40 Si 20 , also same as in Figure 3, i.e. Me 4 Si.…”

Section: Resultsmentioning

confidence: 87%

“…21,24,[37][38][39][40][41][42][43][44] Although the interest was later shifted to the nickel monosilicide for that application, the ternary silicide was then of interest as alternative to CoSi 2 because the addition of Ni improves the nucleation of Co disilicide and reduces the silicide roughness and Si consumption. Therefore, not only all those studies 21,24,[37][38][39][40][41][42][43][44] were based on vacuum deposited extremely thin films but also most of them focused on the disilicide formation from Co rich alloys at high temperatures above 500…”

Section: Resultsmentioning

confidence: 99%

A Study on the Electrodeposition and Silicidation of Nickel-Cobalt Alloys for Silicon Photovoltaic Cell Metallization

Huang¹

2015

ECS J. Solid State Sci. Technol.

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Metallization of silicon solar cells using electroplating is of interest recently as a cheaper replacement of silver screen printing. Light assisted electroplating of Nickel-Cobalt (NiCo) alloys were studied on crystalline silicon (Si) solar cells in this paper. The effect of illumination was investigated in conjunction with the light absorption properties of the plating solution, emission spectrum of the light source as well as the plating current. A solution dependent threshold light intensity was observed, beyond which the solar cells were under reverse bias during electroplating. The detailed compositional depth profiles of the silicide layer were studied along the silicidation reaction using microscopic energy dispersive X-ray spectrum (EDS). A significant improvement in the performance degradation at high temperature thermal stress was observed for solar cells metalized with the ternary silicide. The cost of solar energy compared with fossil fuel is one of the key determining parameters in its adoption by the market. Therefore, ways of saving the manufacturing cost of silicon solar cells are of great interest. The current manufacturing process involves a screenprinting process to metalize the front side with silver paste. While the screen-printing process has been integrated into the process flow with standard tooling, it typically suffers from conversion loss due to the low conductivity of the paste and low line height-width aspect ratio. In addition, the high price of silver potentially limits the cost reduction of the solar cell.Replacing the screen-printed Ag with electroplated high aspect ratio Cu grids has been proposed decades ago.1,2 This method has recently gained more attention due to the high price of Ag and the easy integration of Cu electroplating with laser patterning. The selective emitter formed by the in-situ doping during laser patterning 3-5 further eases the process control for metallization and has the potential to improve the conversion efficiency of the solar cell.Different Cu metallization schemes involving electroplating have been reported. [6][7][8][9][10][11][12][13][14][15][16][17] Most of these schemes involve the formation of Ni silicide either from electroless or electrolytic deposited Ni. [8][9][10][11][12][15][16][17] The electrolytic deposition process in these reports typically involves light, so called light induced or light assisted electrodeposition. The formation of silicide lowers the contact resistance between the metal and Si 18 and thus improves the solar cell performance. Ni and Co silicidation has been extensively studied for the application in complementary metal oxide semiconductor (CMOS) contacts.18-23 The Ni silicidation starts at as low as 300• C for metal rich phases, followed by monosilicide phases around 400• C and silicon rich phases above 800• C. 18 Co silicidation follows a similar phase evolution but at a higher temperature. 24 While the low resistive Co disilicide was originally used in CMOS it suffers from poor nucleation rate and interface roughne...

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“…6 and 51.2 , respectively, and CoSi 2 (220) at 47. 9 . The ramped thermal anneals from room temperature to 900…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…6 While the formation temperature for binary CoSi 2 is reasonably well defined, it has been shown that the onset temperature can be raised or lowered by alloying Co with elements such as Ni, Fe, Ti, and W (Refs. [7][8][9] or by the insertion of an Au or Ti layer. [10][11][12] Another interesting feature of CoSi 2 is its cubic CaF 2 structure with a lattice constant which differs from that of Si by only À1.2% making is possible, in principle, for CoSi 2 to grow epitaxially on silicon single crystal substrates.…”

Section: Introductionmentioning

confidence: 99%

Effect of high temperature deposition on CoSi2 phase formation

Comrie

Ahmed

Smeets

et al. 2013

Journal of Applied Physics

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This paper discusses the nucleation behaviour of the CoSi to CoSi 2 transformation from cobalt silicide thin films grown by deposition at elevated substrate temperatures ranging from 375 C to 600 C. A combination of channelling, real-time Rutherford backscattering spectrometry, real-time x-ray diffraction, and transmission electron microscopy was used to investigate the effect of the deposition temperature on the subsequent formation temperature of CoSi 2 , its growth behaviour, and the epitaxial quality of the CoSi 2 thus formed. The temperature at which deposition took place was observed to exert a significant and systematic influence on both the formation temperature of CoSi 2 and its growth mechanism. CoSi films grown at the lowest temperatures were found to increase the CoSi 2 nucleation temperature above that of CoSi 2 grown by conventional solid phase reaction, whereas the higher deposition temperatures reduced the nucleation temperature significantly. In addition, a systematic change in growth mechanism of the subsequent CoSi 2 growth occurs as a function of deposition temperature. First, the CoSi 2 growth rate from films grown at the lower reactive deposition temperatures is substantially lower than that grown at higher reactive deposition temperatures, even though the onset of growth occurs at a higher temperature, Second, for deposition temperatures below 450 C, the growth appears columnar, indicating nucleation controlled growth. Elevated deposition temperatures, on the other hand, render the CoSi 2 formation process layer-by-layer which indicates enhanced nucleation of the CoSi 2 and diffusion controlled growth. Our results further indicate that this observed trend is most likely related to stress and changes in microstructure introduced during reactive deposition of the CoSi film. The deposition temperature therefore provides a handle to tune the CoSi 2 growth mechanism. V C 2013 AIP Publishing LLC. [http://dx

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Nucleation and diffusion during growth of ternary Co1−xNixSi2 thin films studied by complementary techniques in real time

Cited by 14 publications

References 38 publications

On the nucleation of PdSi and NiSi2 during the ternary Ni(Pd)/Si(100) reaction

On the nucleation of PdSi and NiSi2 during the ternary Ni(Pd)/Si(100) reaction

A Study on the Electrodeposition and Silicidation of Nickel-Cobalt Alloys for Silicon Photovoltaic Cell Metallization

Effect of high temperature deposition on CoSi2 phase formation

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