Femtosecond versus nanosecond laser micro-machining of InP: a nondestructive three-dimensional analysis of strain

Xu, Lu; Lowney, D.; McNally, Patrick J.; Borowiec, A.; Lankinen, Aapo; Tuomi, T.; Danilewsky, A.N.

doi:10.1088/0268-1242/22/8/024

Cited by 4 publications

(5 citation statements)

References 25 publications

(56 reference statements)

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“…We have evidenced a correlation between the place where damage takes place and the location of the maximal residual retardance around the mitigated site. Then again an extensive work that we will consider in a near future involving local analysis (micro-Raman spectrocopy for instance is well adapted [27]) associated with an accurate metrology of LIDT is needed to understand the potential mechanisms that can be involved. Also, we have developed a thermo-mechanical model of CO 2 laser interaction with fused silica with applications in the optimization of the mitigation of damage growth process.…”

Section: Resultsmentioning

confidence: 99%

Investigation of stress induced by CO2 laser processing of fused silica optics for laser damage growth mitigation

Gallais¹,

Cormont²,

Rullier³

2009

Opt. Express

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Laser damage mitigation' is a process developed to prevent the growth of nanosecond laser-initiated damage sites under successive irradiation. It consists of re-fusing the damage area with a CO2 laser. In this paper we investigate the stress field created around mitigated sites which could have an influence on the efficiency of the process. A numerical model of CO2 laser interaction with fused silica is developed. It takes into account laser energy absorption, heat transfer, thermally induced stress and birefringence. Residual stress near mitigated sites in fused silica samples is characterized with specific photoelastic methods and theoretical data are compared to experiments. The stress distribution and quantitative values of stress levels are obtained for sites treated with the CO2 laser in various conditions of energy deposition (beam size, pulse duration, incident power). The results provided evidence that the presence of birefringence/residual stress around the mitigated sites has an effect on their laser damage resistance.

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Section: Resultsmentioning

confidence: 99%

Investigation of stress induced by CO2 laser processing of fused silica optics for laser damage growth mitigation

Gallais¹,

Cormont²,

Rullier³

2009

Opt. Express

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“…The PSD data clearly indicate that in addition to the fundamental periodicity other periodicities are also present due to a large amount of microroughness in the structures and their magnitudes increase with the number of laser shots. Though we have kept the pulse energy density fixed at 125 mJ cm −2 , the periodicity would vary with increasing energy density for a fixed number of laser pulses [37][38][39][40]. The grating period will increase with energy density for a fixed number of laser shots due to increasing electron concentration and temperature [37] = 2π…”

Section: Resultsmentioning

confidence: 99%

Submicrometre periodic surface structures in InP induced by nanosecond UV laser pulses

Kumar¹,

Soni²

2008

J. Phys. D: Appl. Phys.

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We report fabrication of submicrometre size laser-induced periodic surface structures (ripples) on single crystalline InP by nanosecond (ns) pulsed Nd : YAG laser beam irradiation of fourth harmonic wavelength (266 nm) in HF electrolyte. The ripples are orientated parallel to the laser polarization direction and power spectral density analysis reveals reduction in the spatial period of the ripples with increasing number of laser shots. The formation of periodic structures in the presence of electrolyte is empirically explained on the basis of photoelectrochemical etching and variation of periodicity with refractive index change on laser energy and number of laser pulses. From the analysis of energy dispersive x-ray, photoluminescence (PL) and micro-Raman spectroscopy measurements on the rippled surface we conclude that the ripple structures are capped with a thin layer of In2O3. Further, a blue shift of 0.328 eV compared with the band-edge luminescence of InP is estimated from the PL spectrum of the structure fabricated with 200 laser shots. The blue shift of the PL peak is attributed to the quantum confinement effect in the nanometre size structures in the rippled surface. Micro-Raman spectra show good crystalline quality of the surface at lower number of laser shots and its degradation caused by oxidation at the higher number of shots.

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“…Ultrashort lasers offer high intensity to drill, to modify and to process surfaces cleanly by aggressively driving multiphoton, tunnel ionization and electron-avalanche processes [9,10]. Also, nanosecond lasers are proven to have low power, throughput, threshold fluence and redundant debris and recast layer when compared with femtosecond lasers [11][12][13][14]. Studies in femtosecond laser fabrication have been reported at low power and low repetition rate (<1 kHz) [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias

Tan¹,

Panchatsharam²,

Venkatakrishnan³

2009

J. Phys. D: Appl. Phys.

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Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 µm interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at ∼300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 µm diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions.

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Femtosecond versus nanosecond laser micro-machining of InP: a nondestructive three-dimensional analysis of strain

Cited by 4 publications

References 25 publications

Investigation of stress induced by CO2 laser processing of fused silica optics for laser damage growth mitigation

Investigation of stress induced by CO2 laser processing of fused silica optics for laser damage growth mitigation

Submicrometre periodic surface structures in InP induced by nanosecond UV laser pulses

High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias

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