Micro structures in silicon are applied in different fields of industry, medicine and research. Examples are micro mechanical sensors for car security systems, nozzle plates for printer, and optical elements for X-ray...
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ISBN:
(纸本)081944376X
Micro structures in silicon are applied in different fields of industry, medicine and research. Examples are micro mechanical sensors for car security systems, nozzle plates for printer, and optical elements for X-ray beam splitting. Wherever the accuracy of etched silicon structures is not required, laser processes with short pulses and small wave length can be an option with the advantage of shorter process time High quality cutting and drilling of silicon can be achieved by application of diode pumped q-switched Nd:YAG-lasers and harmonics generation. The short pulses (15 ns) and the UV wave length (355 nm) of the Gator UV from Lambda Physik AG, for example, allow a reduction of thermal effects like deposition of molten material and heat effected zones at the edges. Especially in the case of deep structures the ablation plasma causes powerful heating of the walls. An reduction of the plasma temperatures and so the heat influence on the walls can be realized by a small laser wave length with low plasma absorption. Short laser pulse durations are necessary to reduce the heat effected depth or melting due to heat flow from the ablation area into the bulk material. Also the duration and intensity of plasma heating is reduced by short laser pulses. In this contribution the possibilities and limits of laser machining of Si by diode pumped Nd:YAG-lasers with harmonics generation will be presented by means of structures processed by application of a scanner with f-theta-optic. The results will be discussed concerning the experimental setup and the laser parameters.
Recently, the semiconductor substrates for integrated circuits (ICs) have been required to become as thin as 50 pin, because the many electronic devices are strongly demanded to be miniaturized and light-weighted. Mac...
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ISBN:
(纸本)081944376X
Recently, the semiconductor substrates for integrated circuits (ICs) have been required to become as thin as 50 pin, because the many electronic devices are strongly demanded to be miniaturized and light-weighted. Machining of such thin substrates with conventional dicing techniques is very difficult. Therefore, we have proposed to process them using femtosecond laser ablation, expecting advantage of efficient etching without undesirable mechanical and thermal damages such as cracking and melting is expected. In this work, we have investigated the influence of the laser conditions such as pulse duration and fluence on the cutting depth and diameter in order to develop a new photo-dicing technique for very thin ICs. Within the range of pulse energy used in the present experiments, the dependence of the pulse duration did not seem to be significant. It was also found that the lower energy of the laser pulses, the smaller and the deeper, i.e., the sharper holes were formed. The typical cutting depth and diameter for 0.20 mJ/pulse and 5 shots were 17 mum and 40 mum, respectively. These values are very promising for the practical dicing applications.
We performed ablation studies on multi-layer systems at different wavelength - pulse duration combinations. The multi-layer systems of interest, 150 nm thin indium tin oxide (ITO), 200 nm thin polyaniline (PANI) on 1 ...
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ISBN:
(纸本)081944376X
We performed ablation studies on multi-layer systems at different wavelength - pulse duration combinations. The multi-layer systems of interest, 150 nm thin indium tin oxide (ITO), 200 nm thin polyaniline (PANI) on 1 mum thick photo resist, and 280 nm PPV/pedot layer-combination on 150 nm thin ITO are optically transparent and used for a variety of industrial applications. One important goal of the study was to determine the possible process window for a complete removal of only the top layer, leaving the remaining layer basically unharmed. The investigations were conducted with the following wavelength - pulse duration combinations: 800 nm. and 180 fs, 800 nm and 5 ps, 266 nm and 150 fs, 266 nm and 5 ns, 532 nm and 5 ns. We generated micro dots, lines and areas to determine the damage threshold, the processing quality and the processing speed for the specified application of selective layer removal. The structures were analyzed by means of optical and atomic force microscopy. In some cases, we observed a strong pulse duration dependence in the ablation threshold, an indication for the observed difficulties using laser pulses in the ns range. Comparative studies at different wavelengths demonstrate that laser pulses in the UV are not necessarily always a first choice to achieve a precise removal of the optically transparent top layer.
Laser welding of polymers using high power diode lasers offers specific process advantages over conventional technologies, such as short process times while providing optically and qualitatively valuable weld seams, c...
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ISBN:
(纸本)081944376X
Laser welding of polymers using high power diode lasers offers specific process advantages over conventional technologies, such as short process times while providing optically and qualitatively valuable weld seams, contactless yielding of the joining energy, absence of process induced vibrations, imposing minimal thermal stress and avoiding particle generation. Furthermore this method exhibits high integration capabilities and automatization potential. Moreover, because of the current favorable cost development within the high power diode laser market laser welding of polymers has become more and more an industrially accepted joining method. This novel technology permits both, reliable high quality joining of mechanically and electronically highly sensitive micro components and hermetic sealing of macro components. There are different welding strategies available, which are adaptable to the current application. Within the frame of this discourse scientific and also application oriented results concerning laser transmission welding of polymers using preferably diode lasers are presented. Besides the used laser systems the fundamental process strategies as well as decisive process parameters are illustrated. The importance of optical, thermal and mechanical properties is discussed. Applications at real technical components will be presented, demonstrating the industrial implementation capability and the advantages of a novel technology.
This paper presents an overview of our study on the subject that we categorically termed "VLSI (very large scale integration) microphotonics". We examine the scientific and technological issues and challenge...
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ISBN:
(纸本)0819443913
This paper presents an overview of our study on the subject that we categorically termed "VLSI (very large scale integration) microphotonics". We examine the scientific and technological issues and challenges concerning three essential steps in this technology: miniaturization, interconnection, and integration of microphotonic devices, circuits and systems in micron or submicron scale. In miniaturization, the issues on the size effect, proximity effect, energy confinement effect, microcavitiy effect, single photon effect, optical interference effect, high field effect, nonlinear effect, noise effect, quantum optical effect, and chaotic noise effect should be addressed. In interconnection, the issues of connecting identical devices (homogeneous interconnection) or non-identical devices (heterogeneous interconnection) have to be examined. Optical alignment between micron-scale devices, minimizing interconnection losses, and maintaining optical modes between devices, are to be considered. In integration, the issues of interfacing same kind of devices, two different kinds of devices, and several or many different kinds of devices have to be addressed. Other issues include the design and packaging of the integrated devices and circuits as a system for reliable function and operation. In the course of this study, we closely follow the experiences of "VLSI microelectronics" so that they can provide lessons, learnings, and insights that microphotonics can benefit from. Similarities, dissimilarities, advantages, and disadvantages of the two technologies are explored in such a way that they can be more effectively utilized by mutual support and complement. Directions for future studies are also discussed.
This paper presents an overview of our study on the subject that is categorically termed >. microelectronics, as we define it here, is an area of scientific and technological study concerning the miniaturization, i...
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ISBN:
(纸本)0819443107
This paper presents an overview of our study on the subject that is categorically termed <photonics>>. microelectronics, as we define it here, is an area of scientific and technological study concerning the miniaturization, interconnection, and integration of photonic devices, circuits, and systems in micron or submicron scale. We examine the scientific and technological issues relating to these matters and discuss the challenges that the microphotonics faces toward the information technology in the 21st century. In the course of this study, we closely follow the experiences of microelectronics side by side, so that they can provide lessons, learnings, and insights that microphotonics can rightfully benefit from in a complementary form. Similarities, dissimilarities, advantages, and disadvantages, merits and demerits of the two technologies are explored in such a way that they can be more effectively utilized by mutual support. Directions for future studies are also discussed with particular emphasis on information technology.
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