Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1644038
E. Lemaire, P. Duysinx, V. Rochus, J. Golinval
The present work is dedicated to the application of topology optimization in the multiphysics field of MEMS. Precisely, it describes how it is possible to maximize pull-in voltage of an electromechanical microsystem for which the optimization domain is insulated from the electric field. The electromechanical coupling is modeled by the use of a monolithic analysis. The optimization task is completed with the help of a sequential convex linear approximation schemes (CONLIN)
{"title":"Topology optimization of electromechanical microsystems against pull-in voltage","authors":"E. Lemaire, P. Duysinx, V. Rochus, J. Golinval","doi":"10.1109/ESIME.2006.1644038","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1644038","url":null,"abstract":"The present work is dedicated to the application of topology optimization in the multiphysics field of MEMS. Precisely, it describes how it is possible to maximize pull-in voltage of an electromechanical microsystem for which the optimization domain is insulated from the electric field. The electromechanical coupling is modeled by the use of a monolithic analysis. The optimization task is completed with the help of a sequential convex linear approximation schemes (CONLIN)","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"24 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79434183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1644032
M. Novotný, L. Jakubka, P. Cejtchaml, I. Szendiuch
This paper describes recent developments made to the finite element modeling of solar cells, extending its capability to handle viscoplastic behavior. It also presents the validation of this approach and results obtained for an interconnection of solar cells. Lifetime predictions are made using the creep strain energy based models of Darveaux. This study discusses the analysis methodologies as implemented in the ANSYS finite element simulation software tool. The aim of this paper is to improve reliability interconnection of solar cells and to increase durability of these structures. Three-dimensional finite element analysis has been applied to determine the independence on different types of substrates and solder pastes. The interpretations of results are divided into two parts. The first part of evaluation discusses the stress distribution in solder joints depend on material properties. Determining a place in the solder with the maximal stress values and determining the stress is distributed for interconnection of solar cells are the result of this investigation. The possible danger solder joint crack is in the place with the maximal stress value. The second part of evaluation discusses the plastic work (DeltaWave ) (Zahn, 2005), where "DeltaWave" is the element volumetric average of the stabilized change in plastic work within the controlled solder element thickness, the number of cycles to crack initiation, the crack propagation rate and giving the total number of cycles to 63.2% sample failure
{"title":"Thermomechanical stressing of solar cells","authors":"M. Novotný, L. Jakubka, P. Cejtchaml, I. Szendiuch","doi":"10.1109/ESIME.2006.1644032","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1644032","url":null,"abstract":"This paper describes recent developments made to the finite element modeling of solar cells, extending its capability to handle viscoplastic behavior. It also presents the validation of this approach and results obtained for an interconnection of solar cells. Lifetime predictions are made using the creep strain energy based models of Darveaux. This study discusses the analysis methodologies as implemented in the ANSYS finite element simulation software tool. The aim of this paper is to improve reliability interconnection of solar cells and to increase durability of these structures. Three-dimensional finite element analysis has been applied to determine the independence on different types of substrates and solder pastes. The interpretations of results are divided into two parts. The first part of evaluation discusses the stress distribution in solder joints depend on material properties. Determining a place in the solder with the maximal stress values and determining the stress is distributed for interconnection of solar cells are the result of this investigation. The possible danger solder joint crack is in the place with the maximal stress value. The second part of evaluation discusses the plastic work (DeltaWave ) (Zahn, 2005), where \"DeltaWave\" is the element volumetric average of the stabilized change in plastic work within the controlled solder element thickness, the number of cycles to crack initiation, the crack propagation rate and giving the total number of cycles to 63.2% sample failure","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"34 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73508128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1644065
A. Dasgupta
The computational engineering community is facing new modeling challenges because the advent of nanotechnology is clearly demonstrating the limitations of classical continuum mechanics. The discrete nature of matter leads to nonlinear and scale-dependent phenomena at the nanoscale, which cannot be captured in simple homogenization schemes such as those used in classical continuum mechanics. Discrete molecular or atomistic modeling clearly indicates the reasons for the inadequacies of classical continuum mechanics. However, discrete modeling still requires intense computational investment that limits its use to problems of very small length scales (sub-microns) and very short time scales (nanoseconds). Thus, although discrete modeling is a valuable technique to gain fundamental scientific insights into nanoscale phenomena, it is not a feasible strategy over length scales and time scales that are important in nanoscale problems of engineering significance. For example, it is still computationally infeasible to construct a discrete atomistic model of a complete nano-electronic device for design optimization purposes. It is equally difficult to develop a discrete molecular description of the construction of a nano-bio sensor that is based on the self-assembly of hundreds of protein molecules onto a functionalized gold substrate. As a final example, consider the difficulty of developing a discrete molecular model of a composite nanodielectric consisting of hundreds of nanoparticles embedded in a continuous matrix material. Clearly, a formal framework is needed to bridge between discrete molecular modeling and classical continuum modeling, for nano-engineering problems
{"title":"Computational Challenges for Reliability Assessment of Next-Generation Micro & Nano Systems","authors":"A. Dasgupta","doi":"10.1109/ESIME.2006.1644065","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1644065","url":null,"abstract":"The computational engineering community is facing new modeling challenges because the advent of nanotechnology is clearly demonstrating the limitations of classical continuum mechanics. The discrete nature of matter leads to nonlinear and scale-dependent phenomena at the nanoscale, which cannot be captured in simple homogenization schemes such as those used in classical continuum mechanics. Discrete molecular or atomistic modeling clearly indicates the reasons for the inadequacies of classical continuum mechanics. However, discrete modeling still requires intense computational investment that limits its use to problems of very small length scales (sub-microns) and very short time scales (nanoseconds). Thus, although discrete modeling is a valuable technique to gain fundamental scientific insights into nanoscale phenomena, it is not a feasible strategy over length scales and time scales that are important in nanoscale problems of engineering significance. For example, it is still computationally infeasible to construct a discrete atomistic model of a complete nano-electronic device for design optimization purposes. It is equally difficult to develop a discrete molecular description of the construction of a nano-bio sensor that is based on the self-assembly of hundreds of protein molecules onto a functionalized gold substrate. As a final example, consider the difficulty of developing a discrete molecular model of a composite nanodielectric consisting of hundreds of nanoparticles embedded in a continuous matrix material. Clearly, a formal framework is needed to bridge between discrete molecular modeling and classical continuum modeling, for nano-engineering problems","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"23 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74929393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1643955
A. Ptchelintsev
This paper describes first results of an ongoing research project on development of an automated procedure of fatigue life assessment of flexible printed circuits (FPCs) by finite element simulation combined with optimization analysis. The methodology is implemented as a plug-in for ABAQUS/CAE. Issues related to fatigue analysis of FPCs are discussed. Initial results of sensitivity analysis are also presented
{"title":"Automated Modeling and Fatigue Analysis of Flexible Printed Circuits","authors":"A. Ptchelintsev","doi":"10.1109/ESIME.2006.1643955","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1643955","url":null,"abstract":"This paper describes first results of an ongoing research project on development of an automated procedure of fatigue life assessment of flexible printed circuits (FPCs) by finite element simulation combined with optimization analysis. The methodology is implemented as a plug-in for ABAQUS/CAE. Issues related to fatigue analysis of FPCs are discussed. Initial results of sensitivity analysis are also presented","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"74 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76553221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1644067
B. Vigna
Micro-electro-mechanical-systems (MEMS) are three-dimensional structures manufactured through silicon micromachining technologies. They made their first appearance in semiconductor fabs in the sixties. Our daily life is full of micromachined products. When we awake in the morning we step in the car to drive to office and many active and passive safety systems, like vehicle dynamic control and air bag, using acceleration and yaw rate sensors, protect our lives. Moreover, car gasoline consumption is very low also thanks to the use of pressure sensors in engine manifolds and fuel lines. When we arrive in the office, most of times we have to print a document, thus using a cheap and fast inkjet printhead, where hundreds of micromachined chambers eject the ink on the paper. Then, we attend a meeting, where a small and compact video-projector, using millions of micromachined mirrors, displays on the wall a shiny and sharp image. But our unconscious interaction with micromachiend products doesn't stop here, it goes on all the day along. MEMS are manufactured in semiconductor fab like the transistors we find in the electronic chips sold every year, but in this case not only electrons are moving. Membranes, cantilever and fluids are the the main moving actors. And thus MEMS reliability assessment methodology has to take into account additional potential failures modes of moving parts. MEMS compete with non-semiconductor based solutions in price and performances. But miniaturization is definitely another big advantages they bring to the consumer market. And this explains why in the last few years we saw the raise of MEMS "consumerization wave"
{"title":"Future of MEMS: An industry point of view","authors":"B. Vigna","doi":"10.1109/ESIME.2006.1644067","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1644067","url":null,"abstract":"Micro-electro-mechanical-systems (MEMS) are three-dimensional structures manufactured through silicon micromachining technologies. They made their first appearance in semiconductor fabs in the sixties. Our daily life is full of micromachined products. When we awake in the morning we step in the car to drive to office and many active and passive safety systems, like vehicle dynamic control and air bag, using acceleration and yaw rate sensors, protect our lives. Moreover, car gasoline consumption is very low also thanks to the use of pressure sensors in engine manifolds and fuel lines. When we arrive in the office, most of times we have to print a document, thus using a cheap and fast inkjet printhead, where hundreds of micromachined chambers eject the ink on the paper. Then, we attend a meeting, where a small and compact video-projector, using millions of micromachined mirrors, displays on the wall a shiny and sharp image. But our unconscious interaction with micromachiend products doesn't stop here, it goes on all the day along. MEMS are manufactured in semiconductor fab like the transistors we find in the electronic chips sold every year, but in this case not only electrons are moving. Membranes, cantilever and fluids are the the main moving actors. And thus MEMS reliability assessment methodology has to take into account additional potential failures modes of moving parts. MEMS compete with non-semiconductor based solutions in price and performances. But miniaturization is definitely another big advantages they bring to the consumer market. And this explains why in the last few years we saw the raise of MEMS \"consumerization wave\"","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"49 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73837357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1644020
S. Mijalkovic
Model-order reduction (MOR) aims at automatic creation of compact and sufficiently accurate approximations of large-scale simulation models for efficient system design and optimization. While MOR is reaching the maturity in the area of linear system, nonlinear MOR applications are still quite sparse. Most of the existing nonlinear MOR approaches employ polynomial approximation of the nonlinear model operator that limits the applicability of the resulting reduced models. The objective of this paper is to introduce a class of truly nonlinear MOR techniques that do not alter the original nonlinear model formulation in the process of MOR subspace projection. The existing and new techniques for the accurate subspace creation and efficient nonlinear projection are discussed separately
{"title":"Truly Nonlinear Model-Order Reduction Techniques","authors":"S. Mijalkovic","doi":"10.1109/ESIME.2006.1644020","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1644020","url":null,"abstract":"Model-order reduction (MOR) aims at automatic creation of compact and sufficiently accurate approximations of large-scale simulation models for efficient system design and optimization. While MOR is reaching the maturity in the area of linear system, nonlinear MOR applications are still quite sparse. Most of the existing nonlinear MOR approaches employ polynomial approximation of the nonlinear model operator that limits the applicability of the resulting reduced models. The objective of this paper is to introduce a class of truly nonlinear MOR techniques that do not alter the original nonlinear model formulation in the process of MOR subspace projection. The existing and new techniques for the accurate subspace creation and efficient nonlinear projection are discussed separately","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"204 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80300800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1643986
R. Gusmeroli, A. Spinelli
We performed 2D quantum-mechanical simulations of double-gate devices with drift-diffusion and ballistic transport models, investigating the performance improvement that may derive from a scattering-free transport. Device performance and trade-offs are analyzed for channel length from 30 to 8 nm
{"title":"Performance Improvement of Ballistic Double-Gate Devices and Design Trade-Offs","authors":"R. Gusmeroli, A. Spinelli","doi":"10.1109/ESIME.2006.1643986","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1643986","url":null,"abstract":"We performed 2D quantum-mechanical simulations of double-gate devices with drift-diffusion and ballistic transport models, investigating the performance improvement that may derive from a scattering-free transport. Device performance and trade-offs are analyzed for channel length from 30 to 8 nm","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"6 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80329409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1643983
J. Urbánek, K. Dušek
The knowledge of actual value of surface tension is important for the understanding to several soldering aspects, such as wetting, joint shape, fluxing action and particularly, for the quantification of solderability testing. High surface tension is required for wave soldering. Values of surface tension are mainly caused by measurement conditions (temperature, ambient-air, inert atmosphere of the different composition etc.). For our measurement we used one of the solderability evaluation methods known as the wetting balance method, which is used to measure wetting force. Wettability tester (sometimes called a meniscograph) was placed in the box with the possibility to reduce oxygen concentration. The measurement was carried out on two different types of solders (lead and lead free) and on non-wetting measurement specimen (teflon, nonstick cylinder). We have measured influence of the temperature and reduced oxygen concentration on the wetting force. The change of the wetting force is related to the change of the surface tension
{"title":"Measurements of the solders surface tension values","authors":"J. Urbánek, K. Dušek","doi":"10.1109/ESIME.2006.1643983","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1643983","url":null,"abstract":"The knowledge of actual value of surface tension is important for the understanding to several soldering aspects, such as wetting, joint shape, fluxing action and particularly, for the quantification of solderability testing. High surface tension is required for wave soldering. Values of surface tension are mainly caused by measurement conditions (temperature, ambient-air, inert atmosphere of the different composition etc.). For our measurement we used one of the solderability evaluation methods known as the wetting balance method, which is used to measure wetting force. Wettability tester (sometimes called a meniscograph) was placed in the box with the possibility to reduce oxygen concentration. The measurement was carried out on two different types of solders (lead and lead free) and on non-wetting measurement specimen (teflon, nonstick cylinder). We have measured influence of the temperature and reduced oxygen concentration on the wetting force. The change of the wetting force is related to the change of the surface tension","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"22 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77880837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1643964
H. Frémont, W. Horaud, K. Weide-Zaage
Studies made by PCB material suppliers concerning the behaviour of PCB towards moisture are mainly done on "raw" material. They don't take into account the presence and repartition of other materials for instance conductive layers. To get knowledge of the behaviour of the actual PCB's with humidity, different measurements were carried out. The desorption during baking at temperatures from 80deg to 120degC, the absorption curves in ambient air (23degC/45%RH), as well as in dry pack storage conditions, and forced absorption under controlled atmosphere (85degC/85%RH) were measured. The absorption and the adsorption were determined by weighting. The saturation concentration at 85%RH/85degC for pure FR4 samples was 11,600 ppm. The moisture ingress depends on the internal track repartition, and thus cannot be directly assessed by measurements. The use of FE-simulations can give information about the moisture distribution in the structures. Under the assumption that the uptake of humidity and the desorption, in composites follow more or less a Fick's law, the measured diffusivities were used as input parameters for FE-simulations. A very good agreement between measurement and simulation for absorption as well as desorption was found for the different temperatures. From the FE-simulations it was found that 8 hours of baking to achieve a dryness of 800 ppm at T=120degC are only sufficient for pure FR4. For samples with copper layers, the baking must be longer. This result proves that copper layers act as blocking planes regarding moisture absorption or desorption. Delamination risks are also investigated. With this simplified model, an easy and fast determination of the diffusion process in actual PCB's, including the conductive layers, is possible
{"title":"Measurements and FE-Simulations of Moisture Distribution in FR4 based Printed Circuit Boards","authors":"H. Frémont, W. Horaud, K. Weide-Zaage","doi":"10.1109/ESIME.2006.1643964","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1643964","url":null,"abstract":"Studies made by PCB material suppliers concerning the behaviour of PCB towards moisture are mainly done on \"raw\" material. They don't take into account the presence and repartition of other materials for instance conductive layers. To get knowledge of the behaviour of the actual PCB's with humidity, different measurements were carried out. The desorption during baking at temperatures from 80deg to 120degC, the absorption curves in ambient air (23degC/45%RH), as well as in dry pack storage conditions, and forced absorption under controlled atmosphere (85degC/85%RH) were measured. The absorption and the adsorption were determined by weighting. The saturation concentration at 85%RH/85degC for pure FR4 samples was 11,600 ppm. The moisture ingress depends on the internal track repartition, and thus cannot be directly assessed by measurements. The use of FE-simulations can give information about the moisture distribution in the structures. Under the assumption that the uptake of humidity and the desorption, in composites follow more or less a Fick's law, the measured diffusivities were used as input parameters for FE-simulations. A very good agreement between measurement and simulation for absorption as well as desorption was found for the different temperatures. From the FE-simulations it was found that 8 hours of baking to achieve a dryness of 800 ppm at T=120degC are only sufficient for pure FR4. For samples with copper layers, the baking must be longer. This result proves that copper layers act as blocking planes regarding moisture absorption or desorption. Delamination risks are also investigated. With this simplified model, an easy and fast determination of the diffusion process in actual PCB's, including the conductive layers, is possible","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"44 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77933632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-24DOI: 10.1109/ESIME.2006.1644045
S. Schonfelder, M. Ebert, J. Bagdahn
The market share of thin semiconductors has continuously increased in microelectronical, micromechanical as well as in the solar industries in the recent years, e.g. due to required flexibility for RFIDs or cost reduction of solar cells. However thin wafers are difficult to handle, because of the increasing flexibility and increasing sensitivity to mechanical, thermal and intrinsic loads in manufacturing and use. Therefore the mechanical properties, especially strength, have to be investigated in order to optimize manufacturing steps with regard to the reliability. In the semiconductor industry one can find a lot of reports about the decreasing strength of thin silicon devices. The small thickness seems to be responsible for early fracture in manufacturing. In this work, the strength of thin silicon is investigated. For the investigation (3times3)mm2-dies with a thickness between 200mum and 48mum made from (100) single crystalline silicon were investigated using the ball on ring test. All specimens were thinned back by grinding and wet-chemical spin-etching for stress relief. The front side was not treated by an additional process. In ball on ring tests the maximum principle stress occurs at the surface at the center of the specimen. Since the stress at the edge of the sample is significantly smaller than the stress at the sample center the fracture starts in the center of the sample. Thus the influence of the back thinning technology can be characterized and the dicing process does not influence the test results. For statistical evaluation 40 specimen of each thickness were tested. The front side was also tested as reference. Weibull theory, based on the weakest link model, was chosen for statistical evaluation. Due to the small thicknesses of the samples the force-displacement curves show a nonlinear relationship. Hence the finite element method in consideration of large deflection (geometric nonlinearity) was applied to calculate the fracture stress from the fracture force of each specimen. Additional the contact behavior (structural nonlinearity) between ball and specimen was modeled to consider the changing boundary conditions in large deflection. The influence of the chip thickness on the characteristic fracture stress is shown. It can be seen, that the strength is increasing with decreasing sample thickness for both front and back side. The fracture stress increases very strongly in the range of 50...100mum. It has to be kept in mind that all samples were treated with same process steps. Thus it can be assumed that all samples show the same flaw size and flaw distribution. Hence it can be concluded, that the strength of identical manufactured samples depends on the sample thickness for small thicknesses. In the case of very small sample thickness (less than 20mum), some specimen showed buckling in ball on ring test, caused by large deflection. In order to derive reliable stress values in numerical calculation this process of instability ha
{"title":"Influence of the Thickness of Silicon Dies on Strength","authors":"S. Schonfelder, M. Ebert, J. Bagdahn","doi":"10.1109/ESIME.2006.1644045","DOIUrl":"https://doi.org/10.1109/ESIME.2006.1644045","url":null,"abstract":"The market share of thin semiconductors has continuously increased in microelectronical, micromechanical as well as in the solar industries in the recent years, e.g. due to required flexibility for RFIDs or cost reduction of solar cells. However thin wafers are difficult to handle, because of the increasing flexibility and increasing sensitivity to mechanical, thermal and intrinsic loads in manufacturing and use. Therefore the mechanical properties, especially strength, have to be investigated in order to optimize manufacturing steps with regard to the reliability. In the semiconductor industry one can find a lot of reports about the decreasing strength of thin silicon devices. The small thickness seems to be responsible for early fracture in manufacturing. In this work, the strength of thin silicon is investigated. For the investigation (3times3)mm2-dies with a thickness between 200mum and 48mum made from (100) single crystalline silicon were investigated using the ball on ring test. All specimens were thinned back by grinding and wet-chemical spin-etching for stress relief. The front side was not treated by an additional process. In ball on ring tests the maximum principle stress occurs at the surface at the center of the specimen. Since the stress at the edge of the sample is significantly smaller than the stress at the sample center the fracture starts in the center of the sample. Thus the influence of the back thinning technology can be characterized and the dicing process does not influence the test results. For statistical evaluation 40 specimen of each thickness were tested. The front side was also tested as reference. Weibull theory, based on the weakest link model, was chosen for statistical evaluation. Due to the small thicknesses of the samples the force-displacement curves show a nonlinear relationship. Hence the finite element method in consideration of large deflection (geometric nonlinearity) was applied to calculate the fracture stress from the fracture force of each specimen. Additional the contact behavior (structural nonlinearity) between ball and specimen was modeled to consider the changing boundary conditions in large deflection. The influence of the chip thickness on the characteristic fracture stress is shown. It can be seen, that the strength is increasing with decreasing sample thickness for both front and back side. The fracture stress increases very strongly in the range of 50...100mum. It has to be kept in mind that all samples were treated with same process steps. Thus it can be assumed that all samples show the same flaw size and flaw distribution. Hence it can be concluded, that the strength of identical manufactured samples depends on the sample thickness for small thicknesses. In the case of very small sample thickness (less than 20mum), some specimen showed buckling in ball on ring test, caused by large deflection. In order to derive reliable stress values in numerical calculation this process of instability ha","PeriodicalId":60796,"journal":{"name":"微纳电子与智能制造","volume":"1 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2006-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86424017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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