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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Exploiting the Optical Reflection Matrix for OCT Signal Enhancement
摘要： Electric ?elds can be effectively used to sense, manipulate, and move particles in lab-on-a-chip devices. Nevertheless, the throughput of such devices is a critical issue, which can be effectively improved by increasing the height of the microchannels. For this purpose, vertical electrodes are needed in order to apply electrical stimuli homogeneously over the full height of the channel. In this paper, we propose different fabrication processes based on a conformal coating of 3-D SU-8 structures with metal layers, de?ning vertical electrodes in micro?uidic channels with high aspect ratio and uniform coating of the vertical sidewalls. We describe two different strategies to achieve the patterning of connection lines inside the gaps of the pillar electrodes—one based on liftoff and the other based on dry ?lm resist. We show how the liftoff approach allows for high connection densities and high resolution of the patterning inside the 3-D electrode arrays. Moreover, we highlight how the dry ?lm process provides an ef?cient and low-cost alternative when neither high-density patterning nor high resolution is needed. Standard resistive and impedance measurements show high conductivity of the structures whose fabrication process grants standard photolithographic resolution in the de?nition of the electrode features.
关键词： vertical electrodes,microelectrode arrays,SU-8,3D microelectrodes,SU-8/PDMS bonding
更新于2025-09-19 17:13:59
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Excellent quality microchannels for rapid microdevice prototyping: direct CO2 laser writing with efficient chemical postprocessing
摘要： Rapid, simple microchannel prototyping is critical for the development of modern microfluidic devices and platforms. Laser cutting (ablation) using a commercially available continuous wave (CW) CO2 laser followed by thermal bonding is one of the most common approaches for prototyping in thermoplastics such as polymethyl methacrylate (PMMA). However, this technique suffers from poorly controlled channel quality, inconsistent results from solvent-based post-processing, and inconsistency of thermal bonding. We have overcome these challenges through a systematic study of channel ablation in PMMA using a CW CO2 laser. A new solvent treatment approach results in clearly improved microchannel quality and processing consistency, with negligible residual solvent. Thermal bonding of the processed material showed fourfold increase in bonding strength with full retention of PMMA’s favourable optical clarity. As proof of concept, a high-quality three-layered microfluidic prototype is fabricated with this new method and its performance demonstrated.
关键词： CO2 laser,Microfluidics,Nanofluidics,Thermal bonding,Solvent treatment,PMMA
更新于2025-09-19 17:13:59
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Failure rates among metal brackets cured with two high-intensity LED light-curing lamps: an in vivo study
摘要： The objective of this split-mouth clinical trial was to compare bonding failure rates of metal brackets bonded with two different light-emitting diode (LED) light-curing lamps with different high-intensity power outputs. Forty patients were included for a total of 800 brackets that were randomly bonded (left and right sides in a 1:1 ratio) in maxillary and mandibular arches using two different LED devices. An LED of 3200 mW/cm2 and an LED of 5000 mW/cm2 were used in this split-mouth clinical trial. Bonding failures during the initial 6 months of orthodontic treatment were recorded as maxillary versus mandibular, anterior teeth versus posterior teeth, and left side versus right side. Five dropouts were recorded for discontinuing orthodontic treatment and 700 brackets were analysed in total. The bonding failure rates for 3200 and 5000 mW/cm2 LEDs were 6.0 and 7.4 per cent, respectively (P = 0.450), which were not statistically significantly different. There were no significant differences in bracket survival rates between the LEDs used (P = 0.866). The posterior teeth presented a higher index of bond failures (odds ratio, 3.14; 95% confidence interval, 1.68–5.87; P < 0.001). Similar bonding failures were recorded using both LED devices (3200 and 5000 mW/cm2). Significantly more bonding failures occurred in premolar teeth than in anterior teeth.
关键词： LED light-curing lamps,bonding failure rates,metal brackets,orthodontic treatment
更新于2025-09-19 17:13:59
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Chemical Bonding States and Dopant Redistribution of Heavily Phosphorus-doped Epitaxial Silicon Films: Effects of Millisecond Laser Annealing and Doping Concentration
摘要： We investigated the effect of millisecond (ms) laser annealing and doping concentration on the chemical bonding states and dopant behaviors of P-doped epitaxial Si (Si:P) layers grown on Si (100) substrates using high-resolution X-ray photoelectron spectroscopy (HR-XPS), secondary-ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES) measurements. Our XPS results showed that the intensities of P 2p peaks for Si:P films were increased with P concentration and subsequent laser annealing. From the SIMS and AES measurement results, we found that P atoms were slightly accumulated at the near-surface region of the Si:P film by the laser annealing, while macroscopic P concentration being maintained in the whole Si:P films without significant diffusion of P atoms toward the Si (100) substrate. In addition, we performed ex-situ HF cleaning on the as-grown and laser-annealed Si:P films in order to precisely measure the change in chemical states and dopant distribution at the near-surface region. The intensities of the P 2p peak in the as-grown Si:P films were increased after the HF cleaning due to the removal of native oxide layers from the Si:P films. In contrast, the decrease in P 2p peak intensities was observed in the laser-annealed Si:P films after the HF cleaning, indicating the dopant loss from the near-surface region with native oxide removal.
关键词： Millisecond laser annealing,Dopant redistribution,Chemical bonding states,Phosphorus-doped epitaxial silicon films,Doping concentration
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Las Vegas, NV, USA (2019.5.28-2019.5.31)] 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Vertical Laser Assisted Bonding for Advanced "3.5D" Chip Packaging
摘要： In this work the processes of laser assisted bonding (LAB) is compared to thermal compression bonding (TCB). Their respective advantages and disadvantages regarding the assembly of flip chip stacks are compared. It is found, that the LAB allows for faster processing, negligible compression force and creates less internal stress in the chip stack. The concept of “3.5D” stacking is introduced. This new concept allows for the vertical bonding of chips/semiconductors to the sides of a chip stack. The vertically bonded parts can be used to contact the layers, which eliminates the individual necessity for through silicon vias (TSVs).
关键词： 3D-packaging,Silicon interposer,Thermal compression bonding (TCB),Inter metallic phase (IMC-layer),Laser assisted bonding (LAB),System on Package (SOP),Laser beam modulation,vertical Flip Chip bonding
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Las Vegas, NV, USA (2019.5.28-2019.5.31)] 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Enhanced Performance of Laser-Assisted Bonding with Compression (LABC) Compared with Thermal Compression Bonding (TCB) Technology
摘要： A LABC (Laser-Assisted Bonding with Compression) bonder and NCF (Non-Conductive Film) were developed to increase the productivity of the bonding process for the advanced microelectronic packaging technology. The design features of a LABC make its UPH above 1,000. The NCF was applied to both of LAB and TCB (Thermal Compression Bonding Technology). The 780μm-thick daisy chain top and bottom chips with the minimum pitch of 30μm and bump number of about 27,000 were prepared and tested to verify the LABC and NCF technology. The effects of the laser power on the joints quality after the LABC bonding process were investigated and compared with the joints formed by the TCB technology. Finally, the SAT (Scanning Acoustic Tomography) images of the test vehicles before and after the TCO (Pressurized oven) were observed to check the voids in the NCF after the LABC bonding process.
关键词： thermal compression bonding (TCB),bonding performance,non-conductive film (NCF),throughput,laser-assisted bonding with compression (LABC)
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Dark Current Analysis of Vertical p-i-n Photodetectors on a Germanium-on-Insulator Platform
摘要： Dark current of vertical p-i-n photodetectors on a germanium-on-insulator platform was analyzed. The activation energy was found to be from 0.15 to 0.36 eV under reserve bias. The dark current generation was interpreted by Shockley-Read-Hall and trap-assisted-tunneling effects. This work provides the interpretation on germanium-on-insulator photodetectors and suggests the alternative to suppress the dark current generation for Si-based Ge photodetectors.
关键词： Ge-on-insulator,photodetector,activation energy,direct wafer bonding
更新于2025-09-16 10:30:52
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Synthesis and properties of a novel porphyrin–fullerene triad assembled through donor–acceptor bonding
摘要： Complexation of (hydroxy)(oxo)(5,10,15,20-tetraphenylporphyrinato) molybdenum(v) with 2',5'-di(2-pyridyl)-1'-(3-pyridyl methyl)pyrrolidino[70]fullerene leading to a new donor–acceptor triad is characterized by quantitative description of the equilibrium and the reaction rate. The prospects of the triad as a photosynthetic antenna imitator and an active layer in solar energy conversion devices are substantiated.
关键词： solar energy conversion,porphyrin–fullerene triad,donor–acceptor bonding,photosynthesis
更新于2025-09-16 10:30:52
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Direct fabrication mechanism of pre-sintered Si3N4 ceramic with ultra-high porosity by laser additive manufacturing
摘要： Complex structural Si3N4 ceramics with ultra-high porosity were innovatively formed by selective laser sintering (SLS) technology without any binder. Due to rapid cooling rate, the high temperature phase constituent and microstructure of the SLSed Si3N4 poly hollow microspheres (PHMS) were preserved, thus revealing the bonding mechanism of Si3N4 under the nonequilibrium heat source. Si3N4 PHMS are bonded by microvilli composed of bamboo-structure SiO2 nano?ber clusters, stacked SiO2 nanospheres and smooth α-Si3.72N4 nanowires. Finally, the pre-sintered Si3N4 ceramics with a porosity of 80% are directly fabricated in the atmosphere by SLS, which have the enough strength to satisfy the post-treatment requirements.
关键词： Bonding mechanism,Selective laser sintering,Additive manufacturing,Nanostructure,Silicon nitride
更新于2025-09-16 10:30:52
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Development and Analysis of Wafer-Bonded Four-Junction Solar Cells Based on Antimonides With 42% Efficiency Under Concentration
摘要： The highest solar cell efficiencies today are reached with four-junction devices under concentrated illumination. The optimal bandgap combination for realistic four-junction cells is modelled to be 1.89/1.42/1.05/0.68 eV and indeed promises for efficiencies >50%. We present the development and analysis of a wafer-bonded four-junction solar cell based on GaInP/GaAs/GaInAs//GaInAsSb. This concept allows for the implementation of these ideal bandgaps and exhibits at present an efficiency of 42.0±2.5% at a concentration of 599x AM1.5d. The present loss mechanisms in this device are analyzed, which are dominated by current losses due to mismatched subcell currents and absorbing passive layers. Under the assumption of proper current matching, this device would achieve an efficiency above 44%.
关键词： metal-organic vapour phase epitaxy (MOVPE),multijunction solar cells,wafer bonding,Antimonides,four-junction solar cells
更新于2025-09-16 10:30:52