Nanosecond Laser Processing for Improving the Surface Characteristics of Silicon Wafers Cut Using Wire Electrical Discharge Machining

Panchal, Neelkumar; Narayanan, Vishnu; Marla, Deepak

doi:10.1007/s40516-021-00146-2

Cited by 2 publications

(4 citation statements)

References 20 publications

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“…Finally, the phase shift introduced by the focusing lens (∆t in Equation (A1)) is defined as ∆t = t + r 2 2c(f −z) . In Equation (8) we use somewhat more general initial conditions for generality. These conditions correspond to the dynamics of the Gaussian beam in the paraxial approximation:…”

Section: Disclosuresmentioning

confidence: 99%

“…Fine material processing of semiconductors in general, and silicon in particular is a hot topic both in the scientific community as well as in industry. Up to now a lot of effort has been put into surface processing experiments using mainly nanosecond pulse durations and pulse energies above 1 µJ [1][2][3][4][5][6][7][8]. Processing technology has been well understood both on the practical and theoretical level [7,9].…”

Section: Introduction and State Of The Artmentioning

confidence: 99%

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Nonlinearity and wavelength control in ultrashort-pulse subsurface material processing

Richter¹,

Калашников²,

Sorokina³

2022

Preprint

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The pronounced dependence of the nonlinear parameters of both dielectric and semiconductor materials on the wavelength, and the nonlinear interaction between the ultra-short laser pulse and the material requires precise control of the wavelength of the pulse, in addition to the precise control of the pulse energy, pulse duration and focusing optics. This becomes particularly important for fine sub-wavelength single pulse sub-surface processing. Based on two different numerical models and taking Si as example material, we investigate the spatio-temporal behavior of a pulse propagating through the material while covering a broad range of parameters. The wavelength-dependence of material processing depends on the different contributions of two-and tree-photon absorption in combination with the Kerr effect which results in a particularly sharp nonlinear peak at ≈ 2100 nm. We could show that in silicon this makes processing preferable close to this wavelength. The impact of the nonlinear nonparaxial propagation effects on spatio-temporal beam structure is also investigated. It could be shown that with increasing wavelength and large focusing angles the aberrations at the focal spot can be reduced, and thereby cleaner and more precise processing can be achieved. Finally, we could show that the optimum energy transfer from the pulse to the material is within a narrow window of pulse durations between 600 to 900 fs.

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Section: Disclosuresmentioning

confidence: 99%

Section: Introduction and State Of The Artmentioning

confidence: 99%

Nonlinearity and wavelength control in ultrashort-pulse subsurface material processing

Richter¹,

Калашников²,

Sorokina³

2022

Preprint

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show abstract

“…Compared to the aforementioned techniques, the laser ablation process is a fast, stable, cost-effective, and reliable method. Moreover, laser is widely used in photovoltaic applications such as texturing, 6 annealing, 7 and thin layer deposition. 8 Laser ablation is commonly performed using pulsed lasers with pulse durations in the range of nanoseconds (ns), picoseconds (ps), and femtoseconds (fs).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An experimental study on laser ablation of Ultra-thin SiN_x layer of PERC solar cell

Rana

Khatri

Kottantharayil

et al. 2022

Journal of Micromanufacturing

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In this work, a nanosecond green laser (532 nm) is used to generate narrow openings by removing an ultra-thin (85 nm) SiN x layer that is coated on a silicon substrate for application in the fabrication of Passivated Emitter and Rear Contact (PERC) solar cells. An experimental analysis is presented to identify the optimal range of laser parameters for an efficient ablation with minimal damage to the silicon substrate. The ablated samples were characterized using a 3D profilometer to obtain the surface profiles and scanning electron microscope imaging to observe the surface quality. Further, energy-dispersive X-ray line analysis and atom probe tomography were performed to evaluate the nitrogen content on the surface and along the depth, respectively. The experimental results suggest that the SiN x layer starts to ablate only above a threshold laser fluence of 1.4 J/cm2, while the surface bulged out for laser fluence slightly below the ablation threshold. The central part of the ablated region was clean with a negligible nitrogen concentration at the surface, about ∼0.03% at a fluence of 2.4 J/cm2. Nitrogen concentration reduces continuously and almost becomes zero at 80 nm depth, suggesting complete ablation of the SiN x layer for establishing electrical contacts. The ablation width was close to the laser spot diameter only at lower values of the laser fluence. The lowest value of ablation depth was about 180 nm, suggesting that only about 95 nm layer of the silicon is ablated. The study demonstrates that nanosecond laser ablation is a potential technique for ablation of the SiN x layer of PERC solar cells but requires choosing the optimal parameters.

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Nanosecond Laser Processing for Improving the Surface Characteristics of Silicon Wafers Cut Using Wire Electrical Discharge Machining

Cited by 2 publications

References 20 publications

Nonlinearity and wavelength control in ultrashort-pulse subsurface material processing

Nonlinearity and wavelength control in ultrashort-pulse subsurface material processing

An experimental study on laser ablation of Ultra-thin SiN_x layer of PERC solar cell

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Nanosecond Laser Processing for Improving the Surface Characteristics of Silicon Wafers Cut Using Wire Electrical Discharge Machining

Cited by 2 publications

References 20 publications

Nonlinearity and wavelength control in ultrashort-pulse subsurface material processing

Nonlinearity and wavelength control in ultrashort-pulse subsurface material processing

An experimental study on laser ablation of Ultra-thin SiNx layer of PERC solar cell

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Product

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An experimental study on laser ablation of Ultra-thin SiN_x layer of PERC solar cell