308-nm Excimer Laser Research Articles

Embedded Trench Redistribution Layers at 2– $5~\mu \text{m}$ Width and Space by Excimer Laser Ablation and Surface Planer Processes for 20– $40~\mu \text{m}$ I/O Pitch Interposers

This paper reports on one of the first demonstrations of the formation and metallization of 2–5- $\mu \text{m}$ lines and spaces by an embedded trench method in two dry-film polymer dielectrics, Ajinomoto build-up film and preimidized polyimide, without using chemical mechanical planarization. The trenches and vias in 8–15- $\mu \text{m}$ -thick dry-film dielectrics were formed by 308-nm excimer laser ablation, followed by the metallization of the trenches and vias by copper electrodeposition. A low-cost planarization process was used to remove the copper overburden with a surface planer tool. Using an optimized set of materials and processes, multilayer redistribution layers with 2– $5~\mu \text{m}$ trenches and vias were successfully demonstrated. Although thin film processes on silicon wafers have been able to achieve 40- $\mu \text{m}$ I/O pitch for interposers, the materials and processes integrated in this paper are scalable to large panel fabrication at much higher throughput, for interposers and high-density fan-out packaging at lower cost and higher performance than silicon interposers.

A novel multidose tip and minimal blistering dose protocol for psoriasis with the 308-nm excimer laser

A novel multidose tip and minimal blistering dose protocol for psoriasis with the 308-nm excimer laser

Luminescence of α-quartz crystal and silica glass under excitation of excimer lasers ArF (193 nm), KrF (248 nm)

Luminescence of crystalline α-quartz and silica glass was studied under focused laser excitation. It was found that in crystalline α-quartz the luminescence of self-trapped exciton (STE) is excited in two-photon regime with ArF (193nm) excimer laser. In the case of KrF (248nm) laser excitation mainly luminescence related to near surface area is seen even without laser beam focusing. The near surface luminescence has an emission band similar to that of STE in bulk. Temperature quenching is also similar, therefore this luminescence is attributed to STE created in the area of surface. Luminescence decay kinetic of surface STE is longer than bulk STE decay (tens of ms compared to 1ms at 80K). Electron or/and hole self-trapping near the surface is assumed. Their recombination could provide longer duration of surface STE luminescence. Similar surface luminescence was not excited with ArF (193nm) excimer laser. The nature of absorption for laser 248nm photons at surface is not yet clear.Luminescence of silica glass of III type excited with focused beam of KrF (248nm) laser resembles that of previously studied luminescence of STE in silica.

Al2O3−BaTiO3 nanolaminates fabricated by multistationary target pulsed laser deposition with in situ ellipsometry

Layered oxide materials having alternating repeated layer thicknesses of 10 nm or less are difficult to make, especially with sharp interfaces. Nanostructured thin films having repeated layers of two different oxide materials were obtained by using pulsed laser deposition and two independent stationary targets consisting of Al 2 O 3 and BaTiO 3 . Desired thicknesses were achieved by using a specific number of pulses from a 248-nm KrF excimer laser, at an energy of 450 mJ / pulse , a galvanometer mirror system, and a background pressure of oxygen. Trends in material properties were identified by systematically varying the number of pulses for multiple nanostructured thin films and comparing the resulting properties measured using in-situ spectroscopic ellipsometry and ex-situ capacitance measurements, including relative permittivity and loss. Four films were deposited with a goal of having 0.25-, 1-, 4-, and 10-nm thick layers, and each ∼ 220 nm thick. Ellipsometry data were modeled in situ to calculate thickness, n and k . A representative transmission electron microscopy measurement was also collected for the 10-nm sample with corresponding x-ray photoelectron spectroscopy and energy disperive x-ray spectroscopy. Ellipsometry and capacitance measurements were all performed on each of the samples, with one sample having calculated impedance greater than 30 GOhm at 0.001 Hz.

The impact of oral Polypodium leucotomos extract on ultraviolet B response: A human clinical study

There is a rationale for adding systemic photoprotective agents to the current photoprotection regimen. This study was designed to objectively evaluate the molecular and photobiologic effects of oral administration of Polypodium leucotomos extract (PLE). In all, 22 subjects with Fitzpatrick skin phototype I to III were enrolled. On day 1, subjects were irradiated with visible light, ultraviolet (UV) A1, and UVB (using 308-nm excimer laser). Evaluation was done immediately and 24hours after irradiation. On days 3 and 4, irradiation and evaluation process was repeated after ingestion of PLE. Clinical assessments and colorimetry data showed a decrease in UVB-induced changes in 17 of 22 subjects post-PLE administration; histology findings demonstrated such a decrease in all 22 subjects. Only 2 doses of PLE were given. Furthermore, subjects with skin phototypes I to III only were studied. The results suggest that PLE can potentially be used as an adjunctive agent to lessen the negative photobiologic effects of UVB.

A combination of Yiqiqubai granule and 308-nm excimer laser in treatment of segmental vitiligo: a prospective study of 233 patients

Objective: To study the effect of Yiqiqubai granule combined with 308-nm excimer laser treatment for segmental vitiligo (SV).Methods: A prospective research was performed in 233 patients with SV treated in Shanghai General Hospital from 11 February 2015 to 25 August 2016, they were divided into group A (n = 75), group B (n = 78) and group C (n = 80) according to the random number table. Group A was treated with Yiqiqubai granule, group B treated with 308-nm excimer laser and group C treated with combined treatments. The treatment time lasts for 6 months. The clinical efficacy, color-reverse rate and quality of life of the three groups were assessed.Results: After treatment, the effective rate and markedly effective rate of group C (87.5%, 51.3%) were significantly higher than group A (74.7%, 42.7%) and group B (80.8%, 47.4%) (p < .05). Color-reverse rate of group C (66.5 ± 17.6%) was much higher than group A (47.2 ± 16.4%) and group B (49.9 ± 24.2%) (p < .05). Significant differences were found among three groups after treatment in terms of embarrassment, social and work (p < .05).Conclusions: The combination of 308-nm excimer laser and Yiqiqubai granule in the treatment of SV has good clinical effect.

Unsupervised verification of laser-induced breakdown spectroscopy dataset clustering

Laser-induced breakdown spectroscopy is a versatile, optical technique used in a wide range of qualitative and quantitative analyses conducted with the use of various chemometric techniques. The aim of this research is to demonstrate the possibility of unsupervised clustering of an unknown dataset using K-means clustering algorithm, and verifying its input parameters through investigating generalized eigenvalues derived with linear discriminant analysis. In all the cases, principal component analyses have been applied to reduce data dimensionality and shorten computation time of the whole operation. The experiment was conducted on a dataset collected from twenty four different materials divided into six groups: metals, semiconductors, ceramics, rocks, metal alloys and others with the use of a three-channel spectrometer (298.02–628.73nm overall spectral range) and a UV (248nm) excimer laser. Additionally, two more complex groups containing all specimens and all specimens excluding rocks were created. The resulting spaces of eigenvalues were calculated for every group and three different distances in the multidimensional space (cosine, square Euclidean and L1). As expected, the correct numbers of specimens within groups with small deviations were obtained, and the validity of the unsupervised method has thus been proven.

Online monitoring of nanoparticles formed during nanosecond laser ablation

The particle size distribution of dry aerosol originating from laser ablation of glass material was monitored simultaneously with Laser Ablation – Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis and two aerosol spectrometers – Fast Mobility Particle Sizer (FMPS) and Aerodynamic Particle Sizer (APS). The unique combination of LA-ICP-MS and FMPS offers the possibility of measuring the particle size distribution every 1s of the ablation process in the size range of 5.6–560nm. APS extends the information about particle concentration in the size range 0.54–17μm. Online monitoring of the dry aerosol was performed for two ablation modes (spot and line with a duration of 80s) with a 193nm excimer laser system, using the glass reference material NIST 610 as a sample. Different sizes of laser spot for spot ablation and different scan speeds for line ablation were tested. It was found that the FMPS device is capable of detecting changes in particle size distribution at the first pulses of spot laser ablation and is suitable for laser ablation control simultaneously with LA-ICP-MS analysis. The studied parameters of laser ablation have an influence on the resulting particle size distribution. The line mode of laser ablation produces larger particles during the whole ablation process, while spot ablation produces larger particles only at the beginning, during the ablation of the intact layer of the ablated material. Moreover, spot ablation produces more primary nano-particles (in ultrafine mode size range <100nm) than line ablation. This effect is most probably caused by a reduced amount of large particles released from the spot ablation crater. The larger particles scavenge the ultrafine particles during the line ablation mode.

Treatment of vitiligo with 308-nm excimer laser: our experience from a 2-year follow-up of 979 Chinese patients.

The 308-nm excimer laser had been proved to be a time-efficient and potent therapeutic alternative for the management of vitiligo. Different results had been reported in different ethnic populations. To investigate the efficacy and related contributing factors of 308-nm excimer laser in Chinese vitiligo patients. A total of 979 Chinese patients (3478 lesions) with progressive-stage vitiligo who had received 308-nm excimer laser treatment were recruited from the vitiligo clinic of Shandong Provincial Hospital of Dermatology &Venereology from 2012 to 2014. Efficacy of treatment was evaluated at the end of session by two independent dermatologists based on the before and after images taken. Repigmentation was graded on a 4-point scale: grade 1, poor repigmentation (0-25%); grade 2, moderate repigmentation (26-50%); grade 3, good repigmentation (51-75%); grade 4, excellent repigmentation (76-100%). The mean grade of repigmentation was 2.29, 44.22% showed less than 25% repigmentation, 16.27% showed 26-50% repigmentation, 5.95% showed 51-75% repigmentation and 33.55% showed more than 76% repigmentation. The repigmentation of facial lesions was better than lesions located elsewhere (P < 0.0001), the best response was noted in the periorbital region, while lesions on hands and feet showed poor repigmentation (P < 0.0001). The degree of repigmentation was negatively correlated with disease duration (r = -0.268, P < 0.001), age (r = -0.095, P < 0.001) and shape of lesions (r = -0.114, P < 0.001), whereas it was positively correlated with treatment frequency (r = 0.270, P < 0.001). Lesions with concurrent poliosis were more likely resistant to treatments. 308-nm excimer laser appears to be an effective and safe treatment in Chinese vitiligo patients. The clinical response and treatment efficacy was affected by many factors such as age, affected anatomical area, shape of the lesion, disease duration and treatment frequencies.

Treatment of nevus depigmentosus using the 308-nm excimer laser: A retrospective study of 14 patients

Treatment of nevus depigmentosus using the 308-nm excimer laser: A retrospective study of 14 patients

Effectiveness of the 308-nm excimer laser on hypopigmentation after lichen striatus: A retrospective study of 12 patients

Effectiveness of the 308-nm excimer laser on hypopigmentation after lichen striatus: A retrospective study of 12 patients

Vessel wall perforation mechanism of the excimer laser-assisted non-occlusive anastomosis technique.

The excimer laser assisted non-occlusive anastomosis (ELANA) technique is used to make anastomoses on intracerebral arteries. This end-to-side anastomosis is created without temporary occlusion of the recipient artery using a 308-nm excimer laser with a ring-shaped multi-fiber catheter to punch an opening in the arterial wall. Over 500 patients have received an ELANA bypass. However, the vessel wall perforation mechanism of the laser catheter is not known exactly and not 100 % successful. In this study, we aimed to understand the mechanism of ELANA vessel perforation using specialized imaging techniques to ultimately improve its effectiveness. High-speed imaging, high-contrast imaging, and high-sensitivity thermal imaging were used to study the laser wall perforation mechanism and reveal the mechanical and thermal effects involved. In vitro, rabbit arteries were exposed with the special designed laser catheter in a setup representative for the clinical setting, in which blood was replaced with a transparent UV absorbing liquid for visualization. We observed that laser vessel wall perforation was caused by explosive vapor bubbles tearing through the vessel wall, mostly within the first 20 of the total 200 pulses. Thermal effects were minimal. Unsymmetrical tension in the vessel wall inducing migration of the flap during laser exposure was observed in case of unsuccessful wall perforations. The laser wall perforation mechanism in the ELANA technique is primarily mechanical. Symmetric tension in the recipient vessel wall is essential and should be trained by neurosurgeons.

Granuloma annulare successfully treated with the 308-nm excimer laser

Granuloma annulare successfully treated with the 308-nm excimer laser

Effect of a 308-nm excimer laser on atopic dermatitis-like skin lesions in NC/Nga mice.

Atopic dermatitis (AD) is a common inflammatory skin disease that can affect all age groups. It has a relapsing course, which dramatically affects the quality of life of patients. A 308-nm excimer laser has been reported to be a safe and effective treatment for inflammatory skin diseases, although the range of potential application has not been fully explored. The purpose of this study was to evaluate the therapeutic effects of a 308-nm laser on AD-like skin lesions in NC/Nga mice. Dermatophagoides farinae-exposed NC/Nga mice with a clinical score of 12 were treated with either a 308-nm excimer laser or narrowband-UVB (NB-UVB). The effects of the 308-nm excimer laser were evaluated by dermatitis scores, skin histology, skin barrier function, and immunological parameters, including IgE and Th2-mediated cytokines. The 308-nm excimer laser significantly reduced the severity of skin lesions and decreased the total serum levels of IgE and Th2-mediated cytokines. The excimer laser also significantly reduced the inflammatory cellular infiltrate into AD-induced skin lesions. Moreover, treatment with the 308-nm excimer laser led to recovery of skin barrier function in AD-induced skin lesions. The 308-nm excimer laser can be considered a valid and safe therapeutic option for the treatment of localized AD. Lasers Surg. Med. 48:629-637, 2016. © 2016 Wiley Periodicals, Inc.

Formation of copper tin sulfide films by pulsed laser deposition at 248 and 355 nm

The influence of the laser wavelength on the deposition of copper tin sulfide (CTS) and SnS-rich CTS with a 248-nm KrF excimer laser (pulse length τ = 20 ns) and a 355-nm frequency-tripled Nd:YAG laser (τ = 6 ns) was investigated. A comparative study of the two UV wavelengths shows that the CTS film growth rate per pulse was three to four times lower with the 248-nm laser than the 355-nm laser. SnS-rich CTS is more efficiently ablated than pure CTS. Films deposited at high fluence have submicron and micrometer size droplets, and the size and area density of the droplets do not vary significantly from 248 to 355 nm deposition. Irradiation at low fluence resulted in a non-stoichiometric material transfer with significant Cu deficiency in the as-deposited films. We discuss the transition from a non-stoichiometric material transfer at low fluence to a nearly stoichiometric ablation at high fluence based on a transition from a dominant evaporation regime to an ablation regime.

Novel Laser Ablation Sampling Device for the Rapid Radiocarbon Analysis of Carbonate Samples by Accelerator Mass Spectrometry

AbstractConventional radiocarbon analysis of carbonate records with accelerator mass spectrometry (AMS) is time consuming and the achievable spatial resolution is limited, because individual samples have to be taken and need to be converted to graphite for the measurement. A new laser ablation (LA) in situ sampling technique for rapid online 14C analyses of carbonate records by AMS is presented. By focusing a 193-nm ArF excimer laser on carbonate samples, carbon dioxide is generated and can directly be introduced into the gas ion source of an AMS. A dedicated LA cell for AMS was constructed in a way that combines rapid gas exchange with the capacity to carry sample specimen with maximum dimensions of 15×2.5×1.5 cm3. With the presented setup, negative carbon ion currents up to 20 µA were achieved. A low 14C background of 0.011±0.002 F14C was observed on 14C-free marble and different standard and reference materials could be well reproduced within errors. The novel technique allows scanning carbonate samples continuously over several cm per hour with achievable measurement precisions of less than 1% for modern samples. This approach allows acquiring highly spatially resolved 14C records at a far higher rate than with any currently available method.

Analysis of damage threshold of K9 glass irradiated by 248-nm KrF excimer laser

The theoretical model of K9 glass irradiated by a 248-nm KrF excimer laser was established, and a numerical simulation was performed to calculate temperature and thermal stress fields in the K9 glass sample using the finite element method. The laser-induced damage thresholds were defined and calculated, and the effect of repetition frequency and the number of pulses on the damage threshold were also studied. Furthermore, the experiment research was carried out to confirm the numerical simulation. The damage threshold and damage morphology were analyzed by means of a metallurgical microscope and scanning electron microscopy. The simulation and experimental results indicated that the damage mechanism of K9 glass irradiated by a KrF excimer laser was melting damage and stress damage, and the stress damage first appeared inside the K9 glass sample. The tensile stress damage threshold, the compressive stress damage threshold, and the melting damage threshold were 0.64, 0.76, and 1.05 J/cm2, respectively. The damage threshold decreased with increasing repetition frequency and number of laser pulses. The experimental results indicated that the damage threshold of K9 glass was 2.8 J/cm2.

193 nm Excimer laser processing of Si/Ge/Si(100) micropatterns

193nm Excimer laser assisted growth and crystallization of amorphous Si/Ge bilayer patterns with circular structures of 3μm diameter and around 25nm total thickness, is presented. Amorphous patterns were grown by Laser induced Chemical Vapor Deposition, using nanostencils as shadow masks and then irradiated with the same laser to induce structural and compositional modifications for producing crystalline SiGe alloys through fast melting/solidification cycles. Compositional and structural analyses demonstrated that pulses of 240mJ/cm2 lead to graded SiGe alloys with Si rich discs of 2μm diameter on top, a buried Ge layer, and Ge rich SiGe rings surrounding each feature, as predicted by previous numerical simulation.

Monochromatic excimer light (308 nm) for the treatment of skin diseases

As a kind of monochromatic ultraviolet B, 308-nm monochromatic excimer light (MEL) is one of the first choice treatments for vitiligo. There is no significant difference in the therapeutic effect on vitiligo between 308-nm MEL and 308-nm excimer laser. Recent studies have shown that 308-nm MEL can also serve as the treatment of choice for some other chronic skin diseases, such as psoriasis, palmoplantaris pustulosis and alopecia areata. Furthermore, there have been case reports on the use of 308-nm MEL for the treatment of achromic naevus, mycosis fungoides, CD30 + lymphomatoid papulosis, lichen sclerosus, prurigo nodularis, localized scleroderma, granuloma annulare and plasma cell cheilitis. Compared with conventional phototherapy, 308-nm MEL has the advantages of less cumulative radiation dose and lower risks of skin cancers. The main adverse reaction to 308-nm MEL is transient erythema. The therapeutic mechanism of 308-nm MEL is still unclear. Key words: Skin diseases; Lasers, excimer; Vitiligo; Psoriasis; Alopecia areata

Applications of the Excimer Laser: A Review.

The 308-nm excimer laser has been approved by the Food and Drug Administration for the treatment of psoriasis and vitiligo. Its ability to treat localized areas has led to many studies determining its potential in the treatment of focal diseases with inflammation or hypopigmentation. To review the different applications of the 308-nm excimer laser for treating dermatologic conditions. An extensive literature review was conducted by searching PubMed, MEDLINE, and ClinicalKey to find articles pertaining to dermatologic conditions treated with the 308-nm excimer laser. Articles published that contributed to new applications of the excimer laser were included, as well as initial studies utilizing the excimer laser. The outcomes and results were compiled for different dermatologic conditions treated with the excimer laser. The 308-nm excimer laser has a wide range of uses for focal inflammatory and hypopigmented conditions. Treatment is generally well tolerated, with few adverse reactions. Larger studies and studies evaluating the long-term effects of the 308-nm excimer laser are needed.