Non-linear absorption of femtosecond laser pulses in a SiN  layer—influence of silicon doping type

Heinrich, G.; Lawerenz, A.

doi:10.1016/j.solmat.2013.05.004

Cited by 10 publications

(15 citation statements)

References 18 publications

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“…The reported results show a "SiN x island" formation within the lift-off area (Ref. 26 and Figure 1, left side). The "SiN x island" indicates that no complete layer lift-off occurred in that area.…”

mentioning

confidence: 77%

“…26 Further experiments with this laser system served as basis for the TEM steady-state investigations in this article. The pump-probe microscopy setup included laser system 1 as light source with comparable center wavelength k 1 , pulse duration s p1 , and spot radius w 0 .…”

Section: Methodsmentioning

confidence: 99%

“…25 Recently reported results show that besides the lift-off a partial direct ablation of dielectric silicon nitride (SiN x ) layers with IR laser pulses is feasible at fluences well above threshold. 26 In that work, the ablation of thin SiN x layers was investigated for IR laser pulses with pulse durations in the hundred femtosecond regime and fluences from 600 mJ/cm 2 to about 1500 mJ/cm 2 . The reported results show a "SiN x island" formation within the lift-off area (Ref.…”

mentioning

confidence: 99%

“…27 We explained the possible underlying absorption process which leads to the direct SiN x ablation as avalanche ionization with seed electrons from silicon. 26 Thereby, a high amount of excited electrons (N e % 10 22 cm À3 , Ref. 28) is generated in silicon within the first femtoseconds of the laser pulse while the SiN x layer is transparent.…”

mentioning

confidence: 99%

“…Therefore, the SiN x layer is directly ablated because the high electron concentration leads to high nonlinear absorption, strongly localized heating and consequently vaporization of a few ten nm thick part of the SiN x layer. 26 This direct ablation process could provide a possibility to ablate dielectric layers, for example of a solar cell without damaging the underlying silicon crystal and thus improving the electrical properties like the contact resistance. 7 To verify the assumption of a direct laser ablation in the spot center as well as to prove the presented absorption model "avalanche ionization with seed electrons from silicon" following issues will be addressed in this article:…”

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confidence: 99%

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Physical mechanisms of SiNx layer structuring with ultrafast lasers by direct and confined laser ablation

Rapp

Heinrich

Wollgarten

et al. 2015

Journal of Applied Physics

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In the production process of silicon microelectronic devices and high efficiency silicon solar cells, local contact openings in thin dielectric layers are required. Instead of photolithography, these openings can be selectively structured with ultra-short laser pulses by confined laser ablation in a fast and efficient lift off production step. Thereby, the ultrafast laser pulse is transmitted by the dielectric layer and absorbed at the substrate surface leading to a selective layer removal in the nanosecond time domain. Thermal damage in the substrate due to absorption is an unwanted side effect. The aim of this work is to obtain a deeper understanding of the physical laser-material interaction with the goal of finding a damage-free ablation mechanism. For this, thin silicon nitride (SiN x ) layers on planar silicon (Si) wafers are processed with infrared fs-laser pulses. Two ablation types can be distinguished: The known confined ablation at fluences below 300 mJ/cm 2 and a combined partial confined and partial direct ablation at higher fluences. The partial direct ablation process is caused by nonlinear absorption in the SiN x layer in the center of the applied Gaussian shaped laser pulses. Pump-probe investigations of the central area show ultra-fast reflectivity changes typical for direct laser ablation. Transmission electron microscopy results demonstrate that the Si surface under the remaining SiN x island is not damaged by the laser ablation process. At optimized process parameters, the method of direct laser ablation could be a good candidate for damage-free selective structuring of dielectric layers on absorbing substrates. V C 2015 AIP Publishing LLC.

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mentioning

confidence: 77%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Physical mechanisms of SiNx layer structuring with ultrafast lasers by direct and confined laser ablation

Rapp

Heinrich

Wollgarten

et al. 2015

Journal of Applied Physics

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Investigating the Application and Impact of Laser Etching Technology in the Fabrication of Solar Cells

Wang,

Cheng,

Wang

et al. 2024

Physica Status Solidi (a)

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The most crucial initial step in the metallization process of electroplating is the local contact openings in dielectric layers. In this article, an ultraviolet picosecond laser (UV‐ps), is used to open the front and back dielectric layer of the precursor of n‐TOPCon solar cells. By changing the laser parameters and spot overlap rate, the surface morphology of laser etching under different conditions is obtained and characterized by optical microscope and scanning electron microscope. The results indicate that there are three separate laser shock zones in the dielectric layer under the action of Gaussian light spot, and the corresponding ablation mechanisms are proposed. The longitudinal distribution of B element is characterized by secondary ion mass spectrometry to explore the effect of laser on its pn junction. In addition, the electrical characterization of lifetime photoluminescence is measured and calibrated using WCT120, and this indicates that the majority of the amorphous silicon is recrystallized when applying a fast firing oven process, and this hence improve the minority carrier lifetime and implied open‐circuit voltage. The laser damage to the emitter at the laser‐ablated regions is investigated using the emitter saturation current density, J0laser extracted by WCT120.

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Selective femtosecond laser structuring of dielectric thin films with different band gaps: a time-resolved study of ablation mechanisms

2016

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Non-linear absorption of femtosecond laser pulses in a SiN layer—influence of silicon doping type

Cited by 10 publications

References 18 publications

Physical mechanisms of SiNx layer structuring with ultrafast lasers by direct and confined laser ablation

Physical mechanisms of SiNx layer structuring with ultrafast lasers by direct and confined laser ablation

Investigating the Application and Impact of Laser Etching Technology in the Fabrication of Solar Cells

Selective femtosecond laser structuring of dielectric thin films with different band gaps: a time-resolved study of ablation mechanisms

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