Laser Direct Etching Research Articles

Optimization of Electrode Patterns for an ITO-Based Digital Microfluidic through the Finite Element Simulation.

Indium tin oxide (ITO)-based digital microfluidics (DMF) with unique optical and electrical properties are promising in the development of integrated, automatic and portable analytical systems. The fabrication technique using laser direct etching (LDE) on ITO glass has the advantages of being rapid, low cost and convenient. However, the fabrication resolution of LDE limits the minimum line width for patterns on ITO glasses, leading to a related wider lead wire for the actuating electrodes of DMF compared with photolithography. Therefore, the lead wire of electrodes could affect the droplet motion on the digital microfluidic chip due to the increased contact line with the droplet. Herein, we developed a finite element model of a DMF with improved efficiency to investigate the effect of the lead wire. An optimized electrode pattern was then designed based on a theoretical analysis and validated by a simulation, which significantly decreased the deformation of the droplets down to 0.012 mm. The performance of the optimized electrode was also verified in an experiment. The proposed simulation method could be further extended to other DMF systems or applications to provide an efficient approach for the design and optimization of DMF chips.

One-step in-situ low damage etching of SiC/SiC composites by high-temperature chemical-assisted laser processing

SiC/SiC composites have a promising application prospect in the fields of aero-engine turbine blades and other hot-end components due to their excellent properties. It is difficult to machine SiC/SiC composites by traditional mechanical processing because of the ultra-high hardness and anisotropic character. The routinely laser direct processing in the air produce thermal effect damage, resulting in heat-affected zones and microcracks. Here high-temperature chemical-assisted nanosecond laser processing was investigated to realize one-step in-situ fast etching without causing damage to the structure of SiC/SiC composites. Firstly, the chemical wet etching only occurred in the laser-induced local high-temperature region. There was no additional etching damage to the substrate material in the region where the temperature was relatively low. Secondly, chemical liquid served as a transparent constraint layer, the ablation pressure on the material increased in a liquid confined environment. In comparison with laser direct etching in the air, the exposed fiber was not a needle-like structure and tubular structure but turned into a thin and flat tongue-like structure. The etching behavior of 0° fiber layer, 90° fiber layer, and crossing regions of fibers of different directions at low and high laser intensities were studied. Further, the hardness and friction coefficient of SiC/SiC composites after laser direct etching in the air and high-temperature chemical-assisted laser etching were compared. The chemical elementary composition before and after etching was measured to reveal the oxidized and carbonized characteristics. It was concluded that the action mechanism was the combined result of high-temperature decomposition, laser-induced ablation pressure in the liquid confined region, and local chemical wet etching. The results demonstrate that high-temperature chemical-assisted laser etching has some advantages over traditional laser beam machining and is a potential processing method for SiC/SiC composites.

Fabrication of ZnSe Microlens Array for a Wide Infrared Spectral Region

The infrared (IR) is a strategically important band for numerous applications from environment to biochemical imaging. Here a novel IR optical component integrates more than 2000 plano-concave microlenses on the zinc selenide (ZnSe) surface within a footprint of 5×5mm 2 is proposed by a combined method of femtosecond laser direct irradiation and chemical wet etching. Microlenses with diameter from 15 to 30 μm are realized by controlling the laser power and etching time. The uniform close-packed microlens arrays (MLAs) with minimized volume and high transparency at wavelengths of 0.76~22μm are realized. The MLAs have relatively good topography and surface quality. The modulation transfer function (MTF), imaging test and optical-focusing test confirm the outstanding IR imaging. Owing to the merits of micro-size, light weight, high integration and excellent IR imaging performance, the as-fabricated MLA is promising in cutting-edge mid-IR and far-IR application, such as IR sensing system, imaging system, and so on.

A Study on the Laser Direct Etching of Indium-Tin-Oxide-Graphene Multilayer on Glass Substrate

A Study on the Laser Direct Etching of Indium-Tin-Oxide-Graphene Multilayer on Glass Substrate

355 nm全固态紫外激光直写刻蚀硼硅玻璃微通道

355 nm全固态紫外激光直写刻蚀硼硅玻璃微通道

Phase Analysis of Laser Direct Etching and Water Assisted Laser Combined Etching of SiC Ceramics

In this study, to discover the etching mechanism of SiC ceramics under laser direct etching and water-jet assisted laser combined etching, the phenomena of substance change on the etched surface were investigated. Also, the rules of substance transfer in etching are discussed. The elemental content change and the phase change of the etching products on the etched surface were analyzed by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. These studies showed a high amount of carbon black on the etched surface, because of the decomposition of SiC ceramics under the high-power-density laser irradiation. SiC decomposed to Si under the laser irradiation, and the subsequent chemical reaction of Si and O2 easily produced SiO2. The SiO2 on the etched surface melted and vaporized, whereas most of SiO2 was removed through splashing, changing the chemical composition of the etched surface. Following the water jet introduction, an increased amount of O existed on the combined etching surface, because the chemical reaction of SiC and H2O easily produced SiO2 under the high-power-density laser irradiation.

플렉서블 기판 전/후면에서의 레이저를 이용한 ITO/Ag/ITO 전극층의 식각 특성

ITO/Ag/ITO conductive films on PET (polyethylene terephthalate) was etched by a Q-switched diode-pumped neodymiun-doped yttrium vanadate (Nd:YVO4, <TEX>${\lambda}=1064nm$</TEX>) laser. During the laser direct etching, the laser beam was incident on the two different directions of PET and the etching patterns were investigated and analyzed. At a lower repetition rate of laser pulse, the larger laser etched patterns were obtained by laser beam incident on reverse side of PET substrate. On the contrary, at a higher repetition rate, it was possible to find the larger etched patterns in case of the laser beam incidence on forward side of PET substrate. For the laser beam incidence on reverse side, the laser beam is expected to be transferred and scattered through the PET substrate and the laser beam energy is thought to be dependent on the etch laser pulse beam energy.

Silicon-Based Suspended Structure Fabricated by Femtosecond Laser Direct Writing and Wet Etching

Suspended structures have attracted a great deal of attention in the field of micro-technology and nanotechnology for their important functions. However, the fabrication of the suspended structures is typically cumbersome and time-consuming and requires complicated processes, such as multiple deposition, photolithography, and etching. Here, we report a new method of fabricating flexible suspended structures by femtosecond laser direct writing followed by wet chemical alkaline (KOH) etching. Our proposed method will enable convenient and flexible fabrication of suspended structures for a wide variety of applications in the field of micro-technology and nanotechnology.

Sapphire-Based Fresnel Zone Plate Fabricated by Femtosecond Laser Direct Writing and Wet Etching

Here, we report a sapphire-based Fresnel zone plate (FZP), which is fabricated by femtosecond laser direct writing assisted with subsequent wet etching. With this method, we solved the problem of high surface roughness caused by ultrafast femtosecond laser processing. We have obtained $\sim 12$ -nm average surface roughness smaller than 1/25 of the optical working wavelength. As-formed sapphire FZP also exhibited a well-defined geometry. More importantly, ultraviolet (UV) light focusing and imaging can be easily achieved. Due to the high material hardness, thermal and chemical stabilities of sapphire, such sapphire FZP, may have great potential in UV imaging and focusing under some harsh environments.

Experimental Study of Laser Etching on Al2O3-SiC Composite Ceramics

Analyze the composition of micro area of the laser etched surface via X-Ray Energy Dispersive Spectrometer, and by analyzing the elemental change rule of Al2O3-SiC composite ceramics, study the removal mechanism of laser direct etching on Al2O3-SiC composite ceramics, and compare with composite etching of water jet and laser. The results show that: In the process of laser direct etching, Al2O3 mainly happens the molten removal, a large number of tiny molten particles concentrate the etched surface, so the content of aluminum is increased, but for SiC, because of the decomposition needs a more laser energy, so the SiC has a little decomposition. In the process of composite etching of water jet and laser, water jet with certain pressure can wash a lot of molten particles of Al2O3, reducing the accumulation of molten particles of Al2O3, the content of aluminum is decrease, the content of silicon is increased relatively.

Study of the surface morphology of laser etching on engineering ceramics

For the different compositions of Al2O3 ceramics and Al2O3–SiC composite ceramics, studying the effects of ceramic compositions on the surface morphology of laser direct etching, and discussing the impacts of the complex etching of water jet and laser on Al2O3 ceramics and Al2O3–SiC composite ceramics. The results show that: In the process of laser etching, Al2O3 ceramics melt evenly because of the high purity, but for Al2O3–SiC composite ceramics, Al2O3 achieves the melt firstly, SiC is difficult to decompose because of the high decomposing temperature, so it is observed that the powdered SiC without decomposing covers the surface of groove in the SEM; In the process of the composite etching of water jet and laser, water jet can wash a lot of slag covered on the surface of groove and improve the surface morphology of laser etching significantly.

Fabrication of concave spherical microlenses on silicon by femtosecond laser irradiation and mixed acid etching.

All-silicon plano-concave microlens arrays with spherical profiles and good image performance were obtained using femtosecond laser direct irradiation and mixed acid etching. A femtosecond laser was employed to produce microhole arrays on silicon, and the microholes were expanded and smoothed by the mixed acid to form concave microlenses. The effects of the etching time, laser power, and pulse number on the microlens morphology were investigated. This method has potential applications in the fabrication of all-silicon plano-concave microlenses for use in infrared devices.

PC 기판상에 스퍼터링된 투명전도 산화막의 레이저 식각 특성

As a method of simple patterning of transparent conductive oxide (TCO) films deposited on flexible substrates, laser direct etching was carried out on TCO films sputtered on polycarbonate (PC) substrates. As a result of different binding energies in TCO films, indium tin oxide (ITO) and indium gallium zinc oxide (IGZO) were more easily etched than zinc oxide with different <TEX>$Nd:YVO_4$</TEX> laser beam conditions.

Analysis of stress-etching quality based on nanosecond pulse laser electrochemical machining

Nanosecond pulse laser electrochemical etching can remove the electrolytic products of laser irradiated region and so improve the processing stability and processing efficiency. The stress-etching characteristics and the material removal mechanism for aluminum alloy workpiece were investigated theoretically and experimentally by the use of a laser electrochemical machining system. For comparison of processing topography between laser direct etching in air and laser electrochemical machining, the scanning electron microscopy and the optical profilometry were used to detect and analyze etching morphological characteristics of machining areas. Based on the principle of mechanics and electrochemistry, stress-etching principles of laser electrochemical machining were studied. In this study, the effects of processing parameters and machining method on machining quality were explored, and a complex microstructure was processed successfully with reasonable processing parameters. The results show that laser electrochemical machining with better stability can reduce surface roughness and improve machining quality effectively.

The study of the solution concentration influencing on laser-induced electrochemical etching silicon

The laser electrochemical etching process, which combines the laser direct etching process and the electrochemical etching process, is a compound etching technique. In order to further understand the solution concentration influencing on the laser-induced electrochemical etching of silicon; a 248 nm excimer laser as a light source and KOH solution as an electrolyte were adopted in this study. The experiments of micromachining silicon by laser-induced electrochemical etching were carried out. On the basis of the experiments results, the solution concentration influencing on the etching rates in the process of laser electrochemical etching of silicon was researched. The reasons of the etching phenomena were analyzed in detail. The experimental results indicate that the solution concentration influencing on the etching process is mainly rooted in the absorption of different concentration solutions to laser. In general, less absorption and low solution concentration are good for the etching role in the process of laser electrochemical etching.

Rapid fabrication of patterned high-performance conductor poly (vinylidene fluoride) surfaces using a 248nm excimer laser

This work describes a method for rapidly and conveniently fabricating high-performance conductive patterns on poly (vinylidene fluoride) substrates using a 248 nm excimer laser. It shows that the artificial active centre, created by laser direct etching technique, could facilely control the formation of modified layer, avoiding the laser threshold in processing. Using the etching lines to structure the nonconductive paths, the controllable patterns can be formed in selective areas through the designed photo-mask when 248nm laser irradiation. The modified layer exhibits a high-grade electrical conductivity of 2.80 Ω(-1)cm(-1) increased by 13 orders of magnitude, and the considerable improvement in conductivity could be attributed to the carbon enrichment, especially the structural formation of C-C.

A new laser direct etching method of indium tin oxide electrode for application to alternative current plasma display panel

For cost effective fabrication and time of alternative current plasma display panels (AC PDPs), an indium tin oxide (ITO) layer was patterned directly with a Q-switched diode pumped Nd:YVO 4 laser ( λ = 1064 nm). As experimental results, 500 mm/s scan speed with 40 kHz repetition rate was suitable for the application to AC PDP ITO electrode. In comparison with the chemically wet-etched ITO patterns by photolithography method, laser-ablated ITO patterns showed the formation of shoulders at the edge of the ITO lines and a ripple-like structure of the etched bottom. By dipping the laser-ablated ITO films in the chemical etching solution for 30 s at 50 °C, the shoulders were effectively removed without affecting the discharging properties of AC PDP.

Laser direct writing on structured substrates

Laser direct writing has been used to pattern silicon masking layers on highly structured substrates. Laser direct etching of silicon in chlorine and laser-induced local oxidation of hydrogen-passivated silicon have been applied to write the patterns into the silicon layer which served as an etch mask for wet and dry etching processes.

Fast three-dimensional laser micromachining of silicon for microsystems

The application of laser direct etching of silicon in developing and processing devices for microelectromechanical systems is discussed. The direct write system presented in this paper features high writing speed, high resolution and large access range. Direct micromachining of truly three-dimensional structures, rapid prototyping, processing on non-planar substrates, deep structuring such as drilling and cutting, and complementary processing and post-processing through laser direct etching are demonstrated. Examples include prototypes of micromachined diffuser/nozzle elements, illustrating the potential for microfluidic devices, lens arrays and structures cut out of a membrane, showing the high flexibility of this process.

Laser direct etching of silicon on oxide for rapid prototyping

Structures have been etched in poly-silicon and amorphous silicon deposited on silicon oxide by laser direct writing. These patterns can be written with a high resolution and transferred to the underlying material via reactive ion etching. Three-dimensional structures can be obtained by multiple exposure of the silicon mask. Due to the fast turnaround time of direct writing processes, this technique can be applied for rapid prototyping of large-scale structures.