Dissertations / Theses on the topic 'Susceptores'

Microwave tempering experiments were conducted on frozen blocks of shrimp (FSB) and the results were used to help determine if microwave tempering of FSB is an improved thawing method over the current, traditional method, water immersion. Results of the microwave tempering experiments were also used to help determine which microwave tempering method amongst those explored by this study is most effective. Complete thawing of a FSB in a microwave oven was found to be impractical; however, using a combination of microwave tempering followed by water immersion can successfully thaw a FSB. After a microwave tempering experiment was conducted, the final stages of thawing were completed by using the traditional water immersion method. The amount of time to complete the thawing was recorded and is referred to as the additional thawing time. The amount of shrimp cooked during microwave tempering was also recorded and calculated as a percent. The additional thawing time and the percentage of shrimp cooked were used as criteria to compare microwave tempering experiments and also to compare microwave tempering experiments with the current method. The first set of microwave tempering experiments explored the advantages of freezing a microwave susceptive material within the FSB before microwave tempering. FSBs with susceptors and FSBs without susceptors were tempered in a microwave oven. The FSBs were tempered in a 2450 MHz microwave oven at 255 W for 35 minutes and at 406 W for 22 minutes. The results showed that the addition of susceptors does improve the microwave tempering process. The percentage of cooked shrimp and the additional thawing time was less for FSBs with susceptors than for FSBs without susceptors. The susceptors seem to help distribute the microwave energy more evenly, which reduces runaway heating and in turn reduces the amount of shrimp cooked. When compared to the current method, microwave tempering with susceptors reduced the total thawing time by 45% while microwave tempering without susceptors reduced the total thawing time by 43%. Both microwave tempering methods, with and without susceptors, are an improvement over the current method. The addition of susceptors does improve the microwave tempering process; however, the improvements are not significant enough to justify its recommendation. The second set of microwave tempering experiments explored the advantages of pulse microwave tempering. During pulsed microwave tempering the microwave oven was set to a high power level and was turned ON for a period of time and then OFF for a period of time. The ON/OFF pattern was repeated throughout the microwave tempering process. Several pulsed tempering experiments were conducted at a microwave power level of 848 W and at a microwave power level of 993 W. The results showed that there is no significant advantage to using pulsed microwave energy during tempering as opposed to continuous, fixed microwave energy. The results showed that fixed microwave tempering is more effective than pulsed microwave tempering. The percentage of cooked shrimp was lower for fixed experiments than for pulsed experiments and the additional thawing time was slightly less for fixed experiments than for pulsed experiments. A mathematical model was developed to help predict he temperature profiles of a FSB during microwave tempering. Experimental temperature data were collected at four locations within the FSB during microwave tempering by using four Luxtron Fluoroptic temperature probes and a Luxtron Fluoroptic thermometer. Overall, the temperatures predicted by the model were within 2 oC of the experimental temperatures. After the first 500 seconds or so of microwave tempering, the temperatures predicted by the model were consistently less than the experimental temperatures. From this study it was determined that the most effective microwave tempering method, amongst those conducted in this study, of a 2.2 kg (5 lb) frozen block of shrimp was accomplished by setting the power output to 255 W and the microwave cooking (tempering) time to 35 minutes. As previously mentioned, the addition of susceptors does improve the process but the improvements are not significant enough to justify its recommendation. Pulse tempering is not an improved method over fixed tempering.<br>Master of Science

The coupling efficiency of carbon nanotubes with near infrared laser radiation at 940nm wavelength was investigated. Nanotubes treated with different post processing methods were irradiated at different laser power intensities as dry samples and suspensions in water or ethanol. The interaction with the laser beam was measured and quantified based on the temperature increase in the samples as well as the amount of energy transmitted through them. Parallel experiments using carbon black revealed better performance of carbon nanotubes in terms of coupling efficiency and heat dissipation to their surroundings. It was found that most of the incident radiation on an individual carbon nanotube is absorbed, resulting in extreme local temperature increases proportional to the laser intensity, which can lead to instant tube oxidation in air. Such high heats are efficiently transferred to the material in immediate contact with the nanotubes, increasing its temperature very rapidly. The most intriguing results were obtained in the presence of water where the observations suggested, disintegration of carbon nanotubes with each laser pulse. It is shown that extremely high local temperatures vaporise the water in the immediate vicinity of a carbon nanotube and result in a water-gas reaction. It is further postulated that such effects can be achieved with laser beams at power intensities near the skin tissue's safe exposure thresholds, and therefore can potentially be used as a method of removing nanotubes from living tissue. This has advantages in providing an exit route for nanotubes whether introduced on purpose for reasons of medicine or therapy, or possibly, as a result of inadvertent exposure. Further studies on laser heating and transmission through different dry samples, highlighted that more crystalline structures such as that of a heat-treated nanotube, are more effective in causing extinction of the laser beam and a reduction in the transmitted beam intensity, however the tubes with more defects or with a length comparable to the radiation wavelength are very effective in converting the absorbed laser energy to heat. This effect is exacerbated when the laser beam is polarised parallel to the long axis of the carbon nanotubes. These heating effects were exploited to create welds in high density polyethylene using through transmission laser welding. The resultant welds showed better than or equal mechanical performance to welds made using industrial absorbers such as carbon black or Clearweld®.

Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia<br>With the problems of the economical crisis there was an increase in the consumption of bread. To increase the supply of convenience bread to be used by the consumer, innovations related to the area of baking become extremely important, making companies more competitive. This study intended to develop a formulation of frozen bread in advanced stages of cooking, left a few minutes in the microwave, it is presented to the consumer as freshly baked. Cooking with microwave technology presents problems that can be overcome with technological adjuvants or enhancers. The enhancer used in the baking test samples was the Fermaid® MW, developed by Lallemand Baking Solutions Boulangerie, DK, in order to provide a good dough stability and good texture of the final product. The Fermaid® MW incorporation and the cooking time period in micro-waves, were determined by the Response Surface Methodology (RSM). The studied samples, were cooked in the micro-wave oven, involved in a semi-discontinued aluminum susceptor, a special packaged with the intention that the cooking could be made from the outside to the inside of the bread, inducing the browning of the bread crust. After cooking, the samples were cooled for 5 minutes and the hardness of both the crust and the crumb were analyzed by penetration and compression tests and Texture Profile Analysis (TPA), carried out in the texturómeter. The results were not very conclusive, because the variability of the samples was very high and the susceptor applied did not work as intended, but it was clear that the presence of the enhancer decreased the hardness of the breads, however the formulation that was closer to standard values was the formulation of the central point of the experimental design, with concentration of 1.5% Fermaid® MW and 6 minute heating in microwave oven, with a mean weight of 68.9g.

Microfluidic systems are being used in more and more areas and the demand for such systems is growing every day. To meet such high volume market needs, a cheap and rapid method for sealing these microfluidic platforms which is viable for mass manufacture is highly desirable. In this work low frequency induction heating (LFIH) is introduced as the potential basis of a cost-effective, rapid production method for polymer microfluidic device sealing. Thin metal layers or structured metal features are introduced between the device s substrates and heated inductively. The surrounding material melts and forms a bond when cooling. During the bonding process it is important to effectively manage the heat dissipation to prevent distortion of the microfluidic platform. The size of the heat affected zone (HAZ), and the area melted, must be controlled to avoid blockage of the microfluidic channels or altering the channels wall characteristics. The effects of susceptor shape and area, bonding pressure, heating time, etc, on the heating rate have been investigated to provide a basis for process optimisation and design rules. It was found that the maximum temperature is proportional to the square of the susceptor area and that round shaped susceptors heat most efficiently. As a result of the investigations higher bonding pressure was identified as increasing bond strength and allowing the reduction of heating time and thus the reduction of melt zone width. The use of heating pulses instead of continuous heating also reduced the dimensions of melt zones while maintaining good bond strength. The size of the HAZ was found to be negligible. An analytical model, which can be used to predict the heating rate, was derived. In validating the model by numeric models and experiments it was found that it cannot be used to calculate exact temperatures but it does correctly describe the effect of different heating parameters. Over the temperature range needed to bond polymer substrates, cooling effects were found not to have a significant impact on the heating rate. The two susceptor concepts using thin metal layers (metal-plastic bonds) or structured metal features (plastic-plastic bonds) were tested and compared. While the metal-plastic bonds turned out to be too weak to be useful, the bonds formed using structured susceptors showed good strength and high leakage pressure. Based on the knowledge gained during the investigations a microfluidic device was designed. Different samples were manufactured and tested. During the tests minor leaks were observed but it was found that this was mainly due to debris which occurred during laser machining of the channels. It was concluded that induction bonding can be used to seal plastic microfluidic devices. The following guidelines can be drawn up for the design of susceptors and process optimisation: Materials with low resistivity perform better; For very thin susceptors the effect of permeability on the heating rate is negligible; The cross-sectional area of the susceptor should be as large as possible to reduce resistance; The thickness of the susceptor should be of similar dimensions to the penetration depth or smaller to increase homogeneity of heat dissipation; The shape of the susceptor should follow the shape of the inductor coil, or vice-versa, to increase homogeneity of heat dissipation; The susceptor should form a closed circuit; Higher bonding pressure leads to stronger bonds and allows reduced heating times; Pulsed heating performs better than continuous heating in terms of limited melt area and good bond strength. The drawbacks of the technique are explained as well: introducing additional materials leads to additional process steps. Also the structuring and placement of the susceptor was identified to be problematic. In this project the structured susceptor was placed manually but that is not feasible for mass manufacture. To be able to use the technique efficiently a concept of manufacturing the susceptor has to be found to allow precise alignment of complex designs.

[EN] The objective of the present Doctoral Thesis consist of developing polypropylene (PP) nanocomposites able to be effectively heated and processed by microwave heating. Unpolar polymers like polypropylene are transparent to microwave radiation. Two types of carbonous nanoparticles were studied aiming to increase the capacity of polypropylene to absorb microwave radiation: Carbon nanotubes (CNT) and multilayer graphene (MLG). Nanoparticles were incorporated into polypropylene matrix by melt compounding in co-rotative twin screw extruder. The first phase of the experimental work consisted of evaluating the influence of the processing conditions on the dispersion of susceptor nanoparticles into the polypropylene matrix (PP). The dispersion was evaluated based on the morphology studies and the rheological properties of the nanocomposites with a CNT and MLG content of 1% w/w. The optimum processing conditions were selected for PP/MLG and PP/CNT systems. These conditions were based on the nanoparticles incorporation by means of masterbatch dilution, employment of high shear screw configuration and high extrusion speed (800 rpm). Nanocomposites with different content of MLG and CNT were prepared with the optimum processing conditions. These nanocomposites showed an increase in the mechanical rigidity and higher thermal stability compared to virgin PP. Storage modulus increase in a 125% with respect to the PP with a nanoparticle content of 1% w/w for both nanocomposite systems. MLG showed a lubricant effect similar to graphite when it was incorporated at low percentages. Electrical and dielectric properties analysis determined that the electrical percolation limit for PP/CNT nanocomposite was set around 1% w/w of CNT, while 10% w/w was the percolation limit for PP/MLG systems. Nanocomposites based on CNT showed an increase on the dielectric constant and the loss factor with the CNT content. Therefore, CNT nanocomposites are able to absorb microwave radiation and transform this energy into heat. Nevertheless, dielectric properties of MLG nanocomposites were very low and barely increase with MLG content. The influence of the dispersion degree on the microwave heating effectiveness was analyzed for the nanocomposites with 1% w/w of MLG and CNT. PP/MLG nanocomposites did not show microwave susceptor behaviour with MLG content of 1% w/w. Nonetheless, nanocomposites with 1%w/w of CNT increased the temperature when exposed to microwave radiation. The dispersion grade of CNT in the PP matrix was a very influencing factor. The maximum reached temperature was increased in 230% by varying the processing conditions. Nanocomposites with high content of CNT showed very different values of the mean reached temperature in the microwave due to the higher presence of agglomerates which act as hot spots. Nanocomposites with 1% w/w of CNT showed a very homogeneous heating. For that reason, the nanocomposite of PP with 1% w/w of CNT was selected to develop a prototype produced with microwave heating. The aim of producing a prototype was to validate the heating technique and the performance of the nanocomposite selected as microwave susceptor. A shin-guard was produced with self-reinforced polymers (PP reinforced with PP/CNT fibre) in which the susceptor nanocomposite also acts as mechanical reinforcement.<br>[ES] El objetivo de la presente Tesis Doctoral consiste en el desarrollo de nanocompuestos de polipropileno (PP) capaces de ser calentados y procesados de manera efectiva mediante radiación microondas. Los polímeros apolares como el polipropileno son transparentes a la radiación microondas. Con el fin de aumentar la capacidad del polipropileno para absorber radiación microondas se emplearon dos tipos de nanopartículas carbonosas: nanotubos de carbono (NTC) y grafeno multicapa (GMC). Las nanopartículas se incorporaron en la matriz de polipropileno por mezclado en fundido en extrusora co-rotativa de doble husillo. La primera fase del experimental consistió en evaluar la influencia de las condiciones de procesado en la dispersión de las nanopartículas susceptoras en la matriz de polipropileno (PP). La dispersión fue evaluada en base a la morfología y propiedades reológicas de los nanocompuestos con un contenido del 1% en peso de NTC y GMC. De esta primera fase se seleccionaron las condiciones de procesado más adecuadas para los sistemas PP/GMC y PP/NTC, y que para ambos sistemas coincidieron en la incorporación de las nanopartículas mediante dilución de un masterbatch, el empleo de una configuración de husillo de alta cizalla y la aplicación de velocidades de extrusión altas (800 rpm). Los estudios llevados a cabo en los sistemas nanocompuestos PP/NTC y PP/GMC preparados en las condiciones seleccionadas mostraron un aumento de la rigidez mecánica y de la estabilidad térmica con el incremento del contenido de nanocarga. Se obtuvo un aumento del módulo de almacenamiento del 125% para ambos sistemas con un porcentaje de aditivación en peso del 1%.bEl GMC mostró un efecto lubricante semejante al grafito cuando se incorporó en bajos porcentajes. Del análisis de las propiedades eléctricas y dieléctricas se determinó que el límite de percolación eléctrica para los nanocompuestos de PP/NTC se encuentra alrededor del 1% de NTC, mientras que para los nanocompuestos PP/GMC este límite está alrededor del 10% de GMC. Los nanocompuestos de NTC mostraron un aumento de la constante dieléctrica y del factor de pérdidas con el contenido de NTC. Por lo tanto, los nanocompuestos basados en NTC son capaces de absorber radiación microondas y transformar esta energía en calor. Sin embargo, las propiedades dieléctricas del GMC fueron muy bajas y apenas aumentaron con el contenido de GMC. Se estudió la influencia del grado de dispersión en la efectividad de calentamiento por microondas de los diferentes sistemas nanocompuestos desarrollados con 1% de GMC y NTC. Los nanocompuestos PP/GMC no reflejaron ningún comportamiento susceptor de radiación microondas con contenidos de GMC del 1% en peso. Sin embargo, los nanocompuestos con 1% de NTC (alrededor del umbral de percolación) aumentaron la temperatura al someterse a radiación microondas. El grado de dispersión de los NTC en la matriz de PP mostró ser un factor de gran influencia, pudiendo aumentar la temperatura de calentamiento en un 230% al variar las condiciones de procesado del nanocompuesto. Los valores de temperatura registrados durante el calentamiento por microondas de nanocompuestos PP/NTC con altos porcentajes de carga mostraron una gran disparidad, debido a la presencia de un mayor número de aglomerados que actúan como "hot spots" o puntos calientes. Sin embargo, los nanocompuestos con 1% de NTC mostraron un calentamiento mucho más homogéneo Por ello, en la fase última de este trabajo se seleccionó el nanocompuesto PP/NTC con 1% carga para el desarrollo de un prototipo fabricado mediante calentamiento por microondas, con el fin de validar tanto el nanocompuesto susceptor, como la técnica de calentamiento. Se fabricó de forma exitosa una espinillera para protección deportiva a partir de polímeros auto-reforzados (PP reforzado con fibras de PP+1%NTC) en la que el nanocompuesto susceptor actuaba también de refuerzo mecánico.<br>[CAT] L'objecte d'aquesta tesi doctoral consisteix en el desenvolupament de nanocompostos de polipropilè (PP) capaços d'ésser escalfats i processats de forma efectiva mitjançant radiació microones. Els polímers apolars como el polipropilè són transparents a la radiació microones. Amb la finalitat d'augmentar la capacitat del polipropilè per absorbir radiació microones s'han utilitzat dos tipus de nanopartícules carbonoses: nanotubs de carboni (NTC) i grafè multicapa (GMC). Les nanopartícules s'han incorporat a la matriu de polipropilé mitjançant mesclat en fos amb extrusora co-rotativa de doble cargol. La primera fase de l'experimental va consistir en avaluar la influència de les condicions de processat en la dispersió de les nanopartícules susceptores dins de la matriu de polipropilé (PP). La dispersió va ser avaluada en base a la morfologia i propietats reològiques dels nanocompostos amb un contingut del 1% en pes de NTC y GMC. D'aquesta primera fase es van seleccionar les condicions de processat més adequades per als sistemes PP/GMC i PP/NTC, i que als dos casos es van basar en la incorporació de les nanopartícules mitjançant dilució d'un masterbatch, l'ús d'una configuració d'un cargol d'alta cisalla i l'aplicació de velocitats d'extrusió elevades (800 rpm). Els estudis realitzats als sistemes nanocompostos PP/NTC y PP/GMC preparats en les condicions seleccionades van mostrar un augment de la rigidesa mecànica i de l'estabilitat tèrmica amb l'increment del contingut de nanocàrrega. S'ha obtingut un augment del mòdul d'emmagatzematge del 125% per als dos sistemes amb un percentatge d'additivació en pes de l'1%. El GMC va mostrar un efecte lubricant semblant al grafit quan en va incorporar en baixos percentatges. De l'anàlisi de les propietats elèctriques i dielèctriques es va determinar que el límit de percolació elèctrica per als nanocompostos de PP/NTC es troba al voltant de l'1% de NTC, mentre que per als nanocompostos PP/GMC eixe límit està al voltant del 10% de GMC. Els nanocompostos de NTC van mostrar un augment de la constant elèctrica i del factor de pèrdues amb el contingut de NTC. En conseqüència, els nanocompostos basats en NTC són capaços d'absorbir radiació microones i transformar aquesta energia en calor. No obstant això, les propietats dielèctriques del GMC van ser molt baixes i quasi no van augmentar amb el contingut de GMC. Es va estudiar la influència del grau de dispersió en l'efectivitat de l'escalfament per microones dels diferents sistemes nanocompostos desenvolupats amb 1% de GMC y NTC. Els nanocompostos PP/ GMC no van reflectir cap comportament susceptor de radiació microones amb continguts de GMC del 1% en pes. No obstant això, els nanocompostos amb 1% de NTC (al voltant del llindar de percolació) van augmentar la temperatura al sotmetre's a radiació microones. El grau de dispersió dels NTC a la matriu de PP va mostrar ésser un factor de gran influència i va poder augmentar la temperatura d'escalfament en un 230% al variar les condicions de processat del nanocompost. Els valors de temperatura registrats al llarg de l'escalfament per microones de nanocompostos PP/NTC amb elevats percentatges de càrrega van mostrar una gran disparitat, a causa de la presència d'un major nombre d'aglomerats que actuen com "hot spots" o punts calents. No obstant això, els nanocompostos amb 1% de NTC van mostrar un escalfament molt més homogeni. Com a conseqüència de tot això, a l'última fase d'aquest treball es va escollir el nanocompost PP/NTC amb 1% de càrrega per al desenvolupament d'un prototipus fabricat mitjançant escalfament per microones, amb l'objectiu de validar tant el nanocompost susceptor, como la tècnica d'escalfament. Es va fabricar de forma exitosa una canyellera de protecció esportiva utilitzant polímers autoreforçats (PP reforçat amb fibres de PP+1%NTC) en la qual el nanocompost susceptor actuava també de reforç mecànic.<br>Galindo Galiana, B. (2016). Estudio del comportamiento susceptor de microondas de nanotubos de carbono y grafeno multicapa para su aplicación en el calentamiento de polímeros [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/65615<br>TESIS

碩士<br>國立交通大學<br>機械工程系所<br>102<br>Among all the manufacture process of LED epitaxial growth, MOCVD (Metal-organic Chemical Vapor Deposition) equipment is the mainstream in industry. There are the most common reactors: CCS (Close Coupled Showerhead) and Planetary system of Aixtron; TurboDisc system of Veeco. In which Planetary reactor has the advantage that as the wafer size increases, the capacity increases outstandingly. The key technology of Planetary reactor is the design of the bearing recess flow channel under the substrate holder, but there is no intensive study in Taiwan so far. This study intends to explore the relationship between Planetary substrate holder movement and the hydrogen flow rate, and propose new way to reach same function using the same or less gas consumption.

碩士<br>國立中央大學<br>機械工程學系<br>106<br>Solar energy not only reduces the use of petrochemical energy and emissions of carbon dioxide, but also contributes to the ecological environment and sustainable development. Stability and mass production are the most important consideration for producing high-quality thin-film solar panels. Metal organic chemical vapor deposition (MOCVD) is widely used in depositing large-area and high-quality thin-film solar cells. The aim of this study is using finite element method (FEM) to develop a computer aided engineering (CAE) technique for simulating and analyzing temperature distributions in a low-pressure MOCVD reactor for epitaxial growth of thin films used in solar cells. Temperature at selected positions in certain components is experimentally measured to validate the FEM modeling. An FEM model is constructed based on the design of a commercial low-pressure MOCVD reactor. Simplified components and proper assumptions are applied in the FEM modeling for saving computational time. For practical purpose, the heat transfer settings and thermal boundary conditions in the FEM model are assumed in a way similar to those employed in operation of the given MOCVD reactor. Temperature distributions are calculated for all components and those in heating plates and glass panels are analyzed and compared with the experimental measurements. The difference in the temperature of each measured point on heating plates between experiment and simulation is less than 3.3%. With regard to the temperature uniformity on the top surface of glass panels, the temperature difference measured in experiment is 3.7°C (1.9%) while it is 8°C (4.2%) in the FEM simulation with consideration of a gap between tray and glass panels, for a target temperature of 190°C. The difference between simulation and experiment is attributed to the simplification of transportation components and relevant boundary conditions. Effectiveness of the constructed FEM model is validated by the agreement of overall temperature distributions between simulations and experimental measurements. Therefore, the CAE developed in this study is applicable for effectively designing an MOCVD reactor or optimizing the operational settings for a given MOCVD process. A modified design of heating plates is also considered in this study. Simulation results show that the modified design of heating plates can reduce the temperature difference on glass panels and improve the temperature uniformity.

abstract: This thesis discusses the use of low temperature microwave anneal as an alternative technique to recrystallize materials damaged or amorphized due to implantation techniques. The work focuses on the annealing of high-Z doped Si wafers that are incapable of attaining high temperatures required for recrystallizing the damaged implanted layers by microwave absorption The increasing necessity for quicker and more efficient processing techniques motivates study of the use of a single frequency applicator microwave cavity along with a Fe2O3 infused SiC-alumina susceptor/applicator as an alternative post implantation process. Arsenic implanted Si samples of different dopant concentrations and implantation energies were studied pre and post microwave annealing. A set of as-implanted Si samples were also used to assess the effect of inactive dopants against presence of electrically active dopants on the recrystallization mechanisms. The extent of damage repair and Si recrystallization of the damage caused by arsenic and Si implantation of Si is determined by cross-section transmission electron microscopy and Raman spectroscopy. Dopant activation is evaluated for the As implanted Si by sheet resistance measurements. For the same, secondary ion mass spectroscopy analysis is used to compare the extent of diffusion that results from such microwave annealing with that experienced when using conventional rapid thermal annealing (RTA). Results show that compared to susceptor assisted microwave annealing, RTA caused undesired dopant diffusion. The SiC-alumina susceptor plays a predominant role in supplying heat to the Si substrate, and acts as an assistor that helps a high-Z dopant like arsenic to absorb the microwave energy using a microwave loss mechanism which is a combination of ionic and dipole losses. Comparisons of annealing of the samples were done with and without the use of the susceptor, and confirm the role played by the susceptor, since the samples donot recrystallize when the surface heating mechanism provided by the susceptor is not incorporated. Variable frequency microwave annealing was also performed over the as-implanted Si samples for durations and temperatures higher than the single frequency microwave anneal, but only partial recrystallization of the damaged layer was achieved.<br>Dissertation/Thesis<br>M.S. Materials Science and Engineering 2011

碩士<br>國立中央大學<br>機械工程學系<br>104<br>Metal organic chemical vapor deposition (MOCVD) process is a technology in fabrication of GaN-based optoelectronic devices, such as LEDs. The substrate for growing GaN thin film is usually sapphire. Temperature distribution on the substrate surface is affected by the component and heater configuration in the MOCVD reaction chamber. In addition, wafer warpage is an issue in MOCVD process. The aim of this work is using finite element method (FEM) to systematically calculate the temperature distribution on the surface of susceptor and wafer substrate. Wafer warpage induced by mismatch in coefficient of thermal expansion between substrate and thin film is also investigated. Temperature distribution on the surface of susceptor and wafer substrate in a given MOCVD reactor is calculated by FEM simulation and measured in experiment. According to the temperature distribution on the wafer substrate placed on an original, plain susceptor, designed grooves are made on the back side of susceptor and on the bottom surface of wafer pockets to improve temperature uniformity on the wafer substrate by changing heat transfer conditions in the susceptor and between susceptor and wafer substrate. By doing so, it is expected to produce a better-quality film. Temperature difference in percentage between simulations and experimental results is less than 5%. Effectiveness of the constructed FEM model is validated by such a good agreement between simulations and experimental measurements. Warpage of wafer placed on plain susceptor and on grooved susceptor is also investigated in this study. Simulation results indicate the wafer warpage is effectively reduced by improving temperature uniformity on the wafer substrate through the groove design in susceptor.

碩士<br>國立成功大學<br>航空太空工程學系碩博士班<br>91<br>In this work, we simulate the heat transfer phenomenon in a RTP equipment developed by CSIST. Most of our work focus on the temperature distribution on the wafer, which is heated by lamps from 300K to 1300K in 10 seconds. Effects of the susceptor, including its materials, positions, and height, are thoroughly investigated. Convective heat transfer in the chamber is not taken into consideration, because it is very small compared to the radiative heat transfer during the heating process. According to our investigation, high thermal diffusivity of the susceptor induces high temperature in itself, and absorbs large amount of heat from the wafer. If the heat capacity of the susceptor is large, the heat loss is even worse. Thus, the thermal diffusivity and heat capacity of the susceptor are crucial for the temperature uniformity on the wafer.

碩士<br>國立中央大學<br>機械工程學系<br>105<br>Metal-organic Chemical Vapor Deposition (MOCVD) is a chemical vapor deposition method used for production of single or polycrystalline thin films. In order to improve the growth uniformity of thin film, a robust rotating spindle of the process equipment is essential. The spindle must not only work with high revolution speed and in the high temperature and vacuum environment, but also ensure the stability of the spindle and wafer susceptor. Therefore, a suitable cooling system is required to enhance heat dissipation and life time of the components. Meanwhile, the related design of the spindle must also be able to reduce the axial deflection and vibration of the susceptor to prevent the adverse effects on the flow field over the susceptor surface and the optical measurement of the thin film. The main purpose of the paper is to design a new version of the spindle, to establish a heat transfer analysis FEM model and to conduct an experimental analysis for validation of the FEM model and the performance of the spindle. The spindles are installed in two separate MOCVD experiment chambers. The external of the bearing cooling channel is improved by using a spiral cooling channel to increase the cooling effect. A new rotary joint for the spindle cooling is also designed to ensure sealing of the cooling water during the rotation of the spindle at high speeds. In order to to ensure the cooling of the bearings and magnetic rotary feedthrough against overheating and failure due to the intense heat of the heater, the heat transfer conditions of the spindle must be obtained. In this study, finite element analysis software is used to analyze the cooling performance of each channel of the spindle by using fluid-solid interaction simulation. The analysis results are also compared with the experiment results. The results show that the maximum difference is about 7%, which shows a good agreement of the FEM model with the experiment. The axial deflection of the graphite susceptor and the vibration of the spindle measurements under the high-speed rotation are also measured with all result values within the reasonable range. On the other hand, in order to reduce the axial deflection of the susceptor furthermore, new concepts for susceptor holder mechanism are also proposed in the study by using the Gyroscopic effect. The feasibility of the concept is validated by a running experiment with two prototypes. The results shows that the susceptor can be self-balanced under high rotation speed.

碩士<br>國立中央大學<br>能源工程研究所<br>103<br>MOCVD is the main process for LED. Because of its high temperature environment, the temperature distribution on the surface of susceptor and the flow field of chamber are different with commercial case. The temperature distribution on the surface of susceptor requires high uniformity under Epitaxy process. And the effect of thermal and flow field generated is closely related due to it influences extremely the uniformity of the deposited process, growth rate of film, the lattice quality and the material utilization. Therefore, the analysis of thermal flow field inside the chamber is necessary. Because it can make a decision on the pros and cons of a LED device, and the analyses of the thermal field on the susceptor, the area of epitaxy, heater and the chamber of reactor are very important. In addition, we analyzes the effect of the various flow parameters such as mass flow rate and rotation rate in the chamber. Finally, we couple the distribution of thermal and flow field in the chamber to investigate the uniformity of temperature distribution on the surface of susceptor. Because the graphite susceptor has a disadvantage such as short lifetime. However, with using silicon carbide coating, it not only rises the lifetime but also improves the total thermal conductivity. As the results of these reasons, the analysis of thermal flow field on the heterogeneoussilicon carbide coated surface is necessary. Consequently, we built a high temperature verification chamber and use this chamber to verify the result of simulation on their high accuracy.

碩士<br>國立成功大學<br>機械工程學系<br>89<br>ABSTRACT In low-pressure rapid thermal processing, the heat conduction by the rarefied gas between wafer and susceptor has a significant contribution to the overall heat transfer between wafer and susceptor. In this work, we apply the direct simulation Monte Carlo to compute the one- and two-dimensional heat conduction by the rarefied gas. The results show that the temperature jump at gas-solid interfaces becomes significant, as the gas becomes more rarefied. The thermal conductivity increases with the increasing temperature difference between wafer and susceptor, and also increases with the increase of the accommodation coefficient. The results of two-dimensional simulation show that the temperature around the dent is higher.

碩士<br>國立中央大學<br>能源工程研究所<br>102<br>This study uses the numerical analysis to simulate the high frequency RF induction heating for MOCVD susceptor, the phenomenon of electromagnetic induction heating and distribution of temperature on the susceptor are investigated. Using numerical analysis calculates the 2D axisymmetric model with phenomenon of electromagnetic induction heating in MOCVD susceptor, the research indicates the temperature difference is decreased with increasing space of coil turns and the temperature difference will decrease with the distance between coil and susceptor, and then the space of coil turn is fixed at 0.8 cm with adjusting the distance between coil and susceptor in order to find the uniform temperature distribution on the deposition area of wafer. In this summary, it obtains the temperature difference is only 2.2 K on the deposition area of susceptor with the distance between individual coil and susceptor are 0.5cm, 0.7cm, 0.8cm, 0.5cm, 0.6cm and 0.7cm. Following the 2D axisymmetric model, the research further compares 2D model with 3D model in electromagnetic induction heating. In the 3D model, the result discovers that by twining coil mode which will result in different current density distribution in different positions of susceptor. The current density distribution decides the distribution of heat source. Because of the different distribution of heat source that will result in different temperature distribution on the susceptor. Consequently, by using the optimized arrangement of coil in 2D model and improving the arrangement of coil that the distance between individual coil and susceptor are 0.5cm, 0.5cm, 0.6cm, 0.6cm, 0.7cm and 0.8cm for obtaining the fine temperature distribution on the susceptor.

博士<br>國立交通大學<br>電子物理系所<br>107<br>Recently years, it requires the higher operation speed and lower power consumption was fabricated of nano-scale MOSFETs. Although there has high effectivity dopant activation on source and drain regions that the lower sheet resistance was obtained by the conventional rapid thermal annealing process. But the doping diffusion depth increasing with high thermal budget annealing technologies was enhancing the short channel effect of MOSFETs. In this thesis, we investigated the high activation on dopant source and drain region of fabrication by microwave annealing technology. The annealing temperature by MWA is lower than that by the conventional thermal process. However, the detailed kinetics and mechanisms of MWA are far from well understood. In this study, different impurities implanted in Si substrates to form junction after MWA process were investigated. Secondary ion mass spectrometry (SIMS) and spreading resistance profiling (SRP) were used to analyze the distributions of impurities and dopant activation after MWA and RTA process. In addition, sheet resistance (Rs) measurement by four-point-probe. Solid-phase epitaxial growth (SPEG) and regrowth mechanism of the amorphous Si layer through MWA was observed by cross-section transmission electron microscopy (TEM) with different MWA time. The highly efficient dopant activity and better anneal uniformity can be obtained during the microwave annealing process because the coupling effect was formed on microwave process chamber. The coupling effect has mainly used the quartz to place up the side and bottom side on the sample, based on the coupling effect that the dopant implanted of the sample can be achieved lower sheet resistance and lower leakage rate approximated to 128 ohm/square and 134uA/cm2 current leakage. Then, the simulations of the impact of dielectric susceptors for the electric field distribution in the microwave chamber by fixed frequency (2.45GHz) microwave generator is investigated using the High-Frequency Structure Simulator (HFSS). In addition, we integrate three annealing conditions: (1) reduced distance of quartz pillar, (2) high dielectric constants susceptor, and (3) distribution of transverses wave mode and longitudinal wave mode introduced in this experiment. As those results, we could obtain the lower sheet resistance and better uniformity that there are 146.3 ohms/square and 0.165 %, respectively. Then, we investigate solid phase epitaxy regrowth technologies and phenomenon from the different annealing time by microwave process technology, in the different impurity ions such as 31P, As, BF2, and B with different dopant concentrations such as 1 x 1015 ions/cm2 and 5 x 1015 ions/cm2. Solid-phase epitaxial growth (SPEG) and regrowth mechanism of the amorphous Si layer through MWA was observed by cross-section transmission electron microscopy (TEM) for different MWA time. The average solid phase epitaxy regrowth rate of 0.33nm/s, 0.15nm/s, 0.11nm/s, and 0.07nm/s were distinguish dopant impurity ions 31P, As, BF2, and B with concentrations 5 x 1015 ions/cm2 by the annealing time 100 second. In addition, the solid phase epitaxy regrowth rate and sheet resistance were investigated under the pre-amorphized implantation process. Phase transformation in HZO films was affected by treatment temperature. Here, we proved that compare with RTA the process temperature of the MWA technique was in the range of 600oC and 700oC, besides the formation of orthorhombic phase could be obtained by MWA technique. In addition, the defects and outdiffusion were no significant observed with different thickness of HZO films after MWA. Therefore, the MWA is an effective technique to enhance the orthorhombic phase that indicates the high quality of ferroelectricity films. Finally, on the basis of results in previous chapters, the dopant implanted of the sample can be obtained high activation and suppress dopant diffusion by the low thermal budget of microwave annealing technique. In conclusion, the microwave annealing technique is proposed in this study indicate a great promise for low standby power circuit, low sheet resistance and shallow junctions applications on nano-scale MOSFETs, and monolithic three-dimensional integrated circuits in the future.

碩士<br>國立臺灣大學<br>電機工程學系<br>85<br>As the dimension of devices in ULSI shrinks, in order to minimize the dopantredistribution or grow thin gate oxides, rapid-thermal processing(RTP) become amore and more important technology nowadays based on rapid heating of wafers using high energy light source. However, RTP industrial application is limited by temperaturenonuniformity problem. The temperature nonuniformity may be caused by nonuniformwafer radiation heat loss, convection cooling, and inappropriate lamp position design.In this thesis, we list the conventional temperature compensation methods published so far, and briefly introduce RTP system in chapter 1. In chapter 2, we consider the effects of susceptor,oxidation time, convection, guardring, and wafer etching on the oxide thickness distribution in our RTP system, Bydiscussing the oxide growth mechanism ,we try to find the best oxide growth conditionin our work. A new temperature compensation method for RTP having nonuniform temperature distribution was proposed in chapter 3. We use concentric Si rings with differnet diameters as patterned susceptor between planar susceptor and monitor wafer to compensate the temperature nonuniformity across the processed wafer. By properlyarranging Si rings on the planar quartz or silicon susceptor, we can effectively improvethe oxide thickness uniformity. Temperature gradient from the center to the edge of monitor wafer in RTP can induce thermal stress and slip dislocatioin which are considered to be harmful to theoxide''s electricla properties. In chapter 4, the relation between electrical characteristicsand thickness uniformity is studied. Finally, the conclusion of the works in this thesis is given i chapter 5.

碩士<br>國立中央大學<br>機械工程學系<br>102<br>The aim of this work is using finite element analysis (FEM) to study the effects of thermal load and rotation speed on the structural integrity of a substrate holder module in an MOCVD reaction chamber. Several loading conditions are considered, including thermal load alone and thermal load plus rotation speeds of 10 rpm, 100 rpm, 500 rpm, 1000 rpm, and 1500 rpm. In addition, the wafer bow and residual stress of GaN growth on silicon or sapphire are systematically studied for various scenarios. The effects of size and material of wafer, thickness of film and substrate, buffer layer, and temperature gradient are characterized. Moreover, in order to validate the FEM model constructed in the current study, experimental results of a previous study are applied to assessing the credibility of the numerical methods by comparison of the simulation results with the experimental measurements of wafer bow. The variation trends of wafer bow and curvature radius in simulation agree well with those in experiment such that the constructed model is validated. Therefore, the constructed model is effective in assessing the effect of various parameters acting on a film-substrate system. As the calculated critical stress is less than the strength of material, no structural failure is predicted for all the components in the given substrate holder module under all of the given loading conditions. The variation of critical stress with rotation speed in all of the components is small. Given a similar heat source in the MOCVD reaction chamber, temperature of the upper components such as susceptor, substrate holders, and wafers is higher in the case of sapphire wafer than that in the case of silicon wafer. The temperature gradient of upper components is greater for the silicon wafer case. A greater temperature gradient in the film-substrate system generates a greater wafer bow and residual stress. Therefore, the temperature uniformity is an important parameter for the epitaxial process. The sign of residual stress is different between a GaN film grown on a sapphire wafer and a silicon wafer (compressive for sapphire wafer and tensile for silicon wafer). For growing a GaN thin film, GaN thin film, sapphire wafer is better than silicon wafer in terms of lessening cracking in film. No matter GaN is grown on sapphire wafer or silicon wafer, wafer bow increases and residual stress in the film decreases with an increase in thickness of film. Increasing the thickness of wafer can effectively reduce wafer bow, which is also a method commonly used in industry, but the residual stress in the film is increased. Given a wafer thickness, the size of bow is increased with wafer diameter, which is one of the major challenges in growth of a large-size epitaxial wafer. The magnitude of residual stress in a thin film can be reduced when a thick buffer layer is added between film and wafer. For a lower residual stress, the reliability of a thin film can be improved by the addition of buffer layer.