Low Temperature High Quality Growth of Silicon-Dioxide Using Oxygenation of Hydrogenation-Assisted Nano-Structured Silicon Thin Films

Rouhi, Nima; Esfandyarpour, B.; Mohajerzadeh, S.; Hashemi, Pouya; Hekmatshoar, B.; Robertson, M.

doi:10.1557/proc-0989-a05-08

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…2, the embossed lines (made of silicon oxide) can be generated consistently on a silicon surface with carefully controlled laser parameters. Generally in the silicon oxidation process, the final silicon oxide layer is approximately 54% above and 46% below the original silicon surface which is because of the difference in densities between Si and SiO 2 [36]. Figure 3(a) represents optical microscope topography images of the induced areas after irradiation.…”

Section: Resultsmentioning

confidence: 99%

Maskless lithography using silicon oxide etch-stop layer induced by megahertz repetition femtosecond laser pulses

Kiani¹,

Venkatakrishnan²,

Tan³

et al. 2011

Opt. Express

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In this study we report a new method for maskless lithography fabrication process by a combination of direct silicon oxide etch-stop layer patterning and wet alkaline etching. A thin layer of etch-stop silicon oxide of predetermined pattern was first generated by irradiation with high repetition (MHz) ultrafast (femtosecond) laser pulses in air and at atmospheric pressure. The induced thin layer of silicon oxide is used as an etch stop during etching process in alkaline etchants such as KOH. Our proposed method has the potential to enable low-cost, flexible, high quality patterning for a wide variety of application in the field of micro- and nanotechnology, this technique can be leading to a promising solution for maskless lithography technique. A Scanning Electron Microscope (SEM), optical microscopy, Micro-Raman, Energy Dispersive X-ray (EDX) and X-ray diffraction spectroscopy were used to analyze the silicon oxide layer induced by laser pulses.

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Section: Resultsmentioning

confidence: 99%

Maskless lithography using silicon oxide etch-stop layer induced by megahertz repetition femtosecond laser pulses

Kiani¹,

Venkatakrishnan²,

Tan³

et al. 2011

Opt. Express

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“…Moreover, a hump was observed at the wavenumber of 954 cm −1 indicating the existence of silicon oxide [51,55]. (See Figure 4.4b).…”

Section: Resultsmentioning

confidence: 99%

“…can be generated consistently on a silicon surface with carefully controlled laser parameters. Generally in the silicon oxidation process, the final silicon oxide layer is approximately 54% above and 46% below the original silicon surface which is because of the difference in densities between Si and SiO 2 [55]. Raman spectroscopy was dominated by the signal at wavenumber of 519 cm −1 which is the characteristic peak of silicon (Figure 7.5).…”

Section: Maskless Lithography Using Oxidized/amorphorized Silicon Etch-stop Layer Induced By Mega Hertz Repetition Femtosecond Laser Pulsmentioning

confidence: 99%

Micro/Nano Amorphization/Oxidation Of Silicon Induced By High Repetition Femtosecond Laser Pulses

Kiani¹

2021

Preprint

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The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication. Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses. The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization. The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication.Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses.The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization.The amorphous silicon and silicon oxide can act as an etch stop. Therefore, maskless lithography iis possible with the direct patterning (amorphization and oxidation) of crystalline silicon. Experimental results have proved the feasibility of the proposed concepts. The thin-film of amorphous silicon generated on the silicon substrate has a potential for use in photovoltaic devices and solar cell fabrication. In comparison with previous methods, the direct oxidation/amorphization of silicon induced by the femtosecond laser is a maskless single-step technique which offers a higher flexibility and reduced processing time.

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Convex grid-patterned microstructures on silicon induced by femtosecond laser assisted with chemical etching

Wang

Tian

Luo

et al. 2019

Optics & Laser Technology

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Low Temperature High Quality Growth of Silicon-Dioxide Using Oxygenation of Hydrogenation-Assisted Nano-Structured Silicon Thin Films

Cited by 4 publications

References 10 publications

Maskless lithography using silicon oxide etch-stop layer induced by megahertz repetition femtosecond laser pulses

Maskless lithography using silicon oxide etch-stop layer induced by megahertz repetition femtosecond laser pulses

Micro/Nano Amorphization/Oxidation Of Silicon Induced By High Repetition Femtosecond Laser Pulses

Convex grid-patterned microstructures on silicon induced by femtosecond laser assisted with chemical etching

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