A quality study on the excimer laser micromachining of electro-thermal-compliant micro devices (original) (raw)
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SN Applied Sciences, 2020
This paper presents the process development and characterization towards microstructural realization using laser micromachining for MEMS. Laser micromachining technique is environmental friendly, fast patterning and able to avoid multi steps in conventional lithography based microfabrication techniques. This research focuses on understanding the dimensional properties of materials of the laser beam on the silicon wafers where microstructures were fabricated. Four main parameters like rectangular variable aperture (RVA-XY) size, number of pulse, stage/table feed rate and laser energy play important role in laser ablation process. The pattern of the microchannel or line with 1 cm length was drawn by AutoCAD software or any CAD software. The pattern in the CAD software is then transferred onto the silicon wafer by using laser micromachining. Finally, high power microscope (HPM) and Stylus Profiler will be used as measurement tools for observing and analysing the width and depth of the microchannel structures fabricated by laser micromachining. When using bigger size of RVA, it will lead to bigger microchannel width. There are a little effects or almost comparable in term of microchannel depth if varying all parameters' value. Surface roughness test also needs to be considered before choosing the best setting for the laser ablation.
Development and Modeling of Laser Micromachining Techniques
Laser micromachining has great potential as a MEMS (micro-electromechanical systems) fabrication technique because of its materials flexibility and 3D capabilities. The machining of deep polymer structures with complex, well-defined surface profiles is particularly relevant to micro-fluidics and micro-optics. This paper presents the use of projection ablation methods to fabricate structures and devices aimed at these application areas. A better understanding of the mechanisms of thermodynamics and heat transfer in MEMS is desired to improve the thermal performance of MEMS due to the importance of these physical processes. Ablation rate of the laser depends on temperature, the material properties and accumulation of heat in the work material. In consequence, to control the laser processing, thermal distribution of the sample has to be determined, which can be made by modeling of laser ablation. By using such modeling tool, proper laser parameters can be determined easier and faster. Geometry of the domain under investigation varies during the simulation, because laser pulses remove material from the sample, thermal effects, photochemical and other phenomena still exist and so the modeling of laser ablation is a specialised problem. A two dimensional finite element model is developed in this work for laser ablation of polymers. Model has been further modified for fabrication of curved sufaces utilized in MEMS applications.
KrF Excimer Laser Micromachining of Silicon for Micro-Cantilever Applications
Proceedings of International Electronic Conference on Sensors and Applications, 2014
The conventional photolithography of crystalline silicon techniques is limited to two-dimensional and structure scaling. This can be overcome by using laser micromachine, a technique capable of producing three-dimensional structure and simultaneously avoiding the needs for photomasks. In this paper, we report on the use of RapidX-250 excimer laser micromachine with 248 nm KrF to create in-time mask design and assisting in the fabrication of micro-cantilever structures. Three parameters of the laser micromachine used to aid the fabrication of the micro-cantilever have been investigated; namely the pulse rate (i.e. number of laser pulses per second), laser energy and laser beam size. Preliminary results show that the 35 um beam size and 15 mJ of energy level is the most effective parameter to structure the desired pattern. The parallel lines spacing of the structure can be reached up to 10 um while cutting, holes drilling and structuring the cantilever using the laser beam can be accomplished to as low as 50 um in dimension.
Characterization of MEMS structure on silicon wafer using KrF excimer laser micromachining
2014 IEEE International Conference on Semiconductor Electronics (ICSE2014), 2014
This paper presents preliminary parametric studies of KrF laser micromachining ablation effects on Silicon. Four parameters are studied, namely laser energy, pulse rate, number of laser pulses, and Rectangular Variable Aperture (RVA) in X and Y direction. At present, the study is focused on the production of microchannels using laser micromachine, in which its dimension is examined and measured. We found that the number of laser pulse is non-linearly proportional with the ablated channel width, with the etching rate of approximately 1 to 5 um for 50 laser pulses. This is similar with the measured depth of the microchannel. The changes in the measured channel width are most significant when the laser energy is increased. Some debris and recast can also be observed around the edge of the microchannel particularly during the variation of the laser pulse frequency. When varying the RVA, it is observed that the surfaces of the ablated microchannels are not smooth with a lot of debris accumulated at the channel edge and a few discolorations. Finally, a microcantilever structure is fabricated with the aim of demonstrating the capability of the laser micromachine.
Laser-assisted micromachining techniques: an overview of principles, processes, and applications
Laser-assisted micro-machining (LAMM) has emerged as a transformative technology in precision manufacturing, enabling the creation of highly intricate micro-features on various materials. This paper provides a foundational overview of LAMM technology, exploring its fundamentals, methods, and applications. The construction of the LAMM temperature field is examined because it is crucial to improve its efficiency and cost-effectiveness. The study delves into the development of industrial femtosecond laser micromachining systems, explores fabrication techniques using LAMM, and discusses its role in the production of ceramics and semiconductors. Furthermore, it examines the capabilities of LAMM in creating 3D microstructures and explores the materials commonly used in laser micromachining. Overall, this paper gives valuable insights into the possible uses of laser-based micromachining technologies in various domains, such as the semiconductor industry, microfluidics, optics, etc. and emphasises the need for additional research to overcome its limitations and increase efficiency and cost-effectiveness.
Theoretical aspects of Laser micro machining and its role in new industrial revolution
CETMIE-2017, 2017
A laser micro machining is becoming popular in the industrial world due to its unique characteristics. Miniaturization has changed the path of machining of various materials. The various properties such as high peak intensity, precision, non-thermal interaction and flexibility make micro-laser machining a well accepted tool of machining. The major advantage of laser micro machining is lower aspect ratio, precise laser cutting zone, flexibility and fast processing. The objective of this review article is to analyze the various laser micromachining techniques, challenges in application, research carried out and their characteristics. This article also depicts the comparison between different laser micro-machining sources which have direct impact on the quality of machined surfaces. A comparison between pico-second, micro-second and nano-second laser has been explained with respect to fluence ablation in the machining zone.
2021
Laser beam micromachining (LBMM) and micro electro-discharge machining (µEDM) based sequential micromachining technique, LBMM-µEDM has drawn signi cant research attention to utilizing the advantages of both methods, i.e. LBMM and µEDM. In this process, a pilot hole is machined by the LBMM and subsequently nishing operation of the hole is carried out by the µEDM. This paper presents an experimental investigation on the stainless steel (type SS304) to observe the effects of laser input parameters (namely laser power, scanning speed, and pulse frequency) on the performance of the nishing technique that is the µEDM in this case. The scope of the work is limited to 1-D machining, i.e. drilling micro holes. It was found that laser input parameters mainly scanning speed and power in uenced the output performance of µEDM signi cantly. Our study suggests that if an increased scanning speed at a lower laser power is used for the pilot hole drilling by the LBMM process, it could result in signi cantly slower µEDM machining time. On the contrary, if the higher laser power is used with even the highest scanning speed for the pilot hole drilling, then µEDM processing time was faster than the previous case. Similarly, µEDM time was also quicker for LBMMed pilot holes machined at low laser power and slow scanning speed. Our study con rms that LBMM-µEDM based sequential machining technique reduces the machining time, tool wear and instability (in terms of short circuit count) by a margin of 2.5 x, 9 x and 40 x respectively in contrast to the pure µEDM process without compromising the quality of the holes.
International Journal of Machine Tools and Manufacture, 2008
Laser-assisted mechanical micromachining (LAMM) is a micro-cutting method that employs highly localized thermal softening of the material by continuous wave laser irradiation focused in front of a miniature cutting tool. However, since it is a heat-assisted process, it can induce a detrimental heat-affected zone (HAZ) in the part. This paper focuses on characterization and prediction of the HAZ produced in a LAMM-based micro-grooving process. The heat-affected zone generated by laser heating of H-13 mold steel (42 HRC) at different laser scanning speeds is analyzed for changes in microstructure and microhardness. A 3-D transient finite element model for a moving Gaussian laser heat source is developed to predict the temperature distribution in the workpiece material. The model prediction error is found to be in the 5-15% range with most values falling within 10% of the measured temperatures. The predicted temperature distribution is correlated with the HAZ and a critical temperature range (840-890 1C) corresponding to the maximum depth of the HAZ is identified using a combination of metallography, hardness testing, and thermal modeling.