Bulk Micromachiningmicromachining
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PEE-5740 "Tópicos de Fabricação de Microestruturas" Prof.Prof. Dr.Dr. PatrickPatrick B.B. VerdonckVerdonck Programação Preliminar de aulas de PEE-5740 3o Período de 2004 (13/09) 1o aula: Introdução : Organização, conceitos básicos – Mario Gongora. (20/09) 2o aula: Química da corrosão úmida de silício : Malu + Humber Furlan (27/09) 3o aula: Materiais e processos utilizados na fabricação de microestruturas e de microsensores, Conceitos de fabricação de microestruturas em substratos e em superfície. (04/10) 4o aula: Materiais para fabricação de microestruturas em superfícies : Nilton Morimoto (11/10) 5o aula: Técnicas de fabricação de microestruturas em substratos, (18/10) 6o aula: Técnicas de fabricação de microestruturas em superfícies (25/10) 7o aula: Simulação de microestruturas : Eliphas W. Simões (08/11) 8o aula: Encapsulamento de microestruturas : Mario Gongora (22/11) 9o aula: Processo LIGA e outros processos avançados. (29/11) 10o aula: Prova (06/12) 11o aula: Apresentação dos trabalhos Conceitos Média=Média= 0,2*(Nota0,2*(Nota dede Trabalho)+0.2*(NotaTrabalho)+0.2*(Nota dede Listas)+0.6*(NotaListas)+0.6*(Nota dede Prova)Prova) BIBLIOGRAFIA: 1) M. Madou, Fundamentals of Microfabrication, CRC Press (Boca Raton - New York) (1997) 2) J.N.Zemel and R.Furlan, Microfluidics, capítulo 12 do Handbook of Chemical and Biological Sensors, editado por J.S.Schulz, Inst. of Phys Publishing Inc. (Bristol), (1996). 3) Sensor technology and devices, editado por Ljubisa Ristic, Artech House (Boston), (1994). 4) Semiconductor sensors, editado por S.M Sze, J. Wiley (New York) (1994). 5) Microsensor: principles and applications, editado por J.W.Gardner, J.Wiley (New York) 1994. 6) M. Elwenspoek, H.V. Jansen " Silicon Micromachining", Cambridge University Press, (Cambridge) (1998) 7) Y.X.Li, Plasma etching for integrated silicon sensor appliations, Tese de doutoramento, Delft University, The Netherlands, 1995. 8) Micromachining and Micropackaging of Transducers, editado por C.D. Fung, P.W. Cheung, W.H.Ko, and D.G.Fleming, Elsevier Science Publishers B.V., (Amsterdam) (1985). 9) Artigos relacionados com a disciplina. MEMS evolved from the Microelectronics Revolution IC Industry Timeline 1947 1958 1999 single transistor first IC 10 million transistors So what exactly is MEMS? Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common substrate through the utilization of microfabrication technology or “microtechnology”. Microtechnology Classifications MEMS System MEMS Design Flow Technology Trends TheThe OpportunityOpportunity ofof MEMSMEMS TechnologyTechnology General MEMS Advantages BatchBatch fabricationfabrication ReducedReduced costcost ReducedReduced sizesize IsIs everythingeverything betterbetter smaller?smaller? ReducedReduced powerpower HighHigh precisionprecision NewNew capabilities?capabilities? ImprovedImproved performance?performance? MEMSMEMS ExamplesExamples pressure sensors accelerometers flow sensors inkjet printers deformable mirror devices gas sensors micromotors microgears lab-on-a-chip systems MEMS Applications in Automotive Industry MEMS Applications in Biomedicine MEMS Timeline 1980 1999 Bulk micromachined pressure sensor 2030 ?? TI DMD (1.3 million micro-mirrors) TheThe MicroTechnologyMicroTechnology/MEMS/MEMS ToolTool SetSet Cleanroom plus microfab processes + Micromachining Processes StandardStandard IntegratedIntegrated CircuitCircuit (IC)(IC) ProcessesProcesses IdenticalIdentical toto thosethose usedused inin ICIC fabricationfabrication GenerallyGenerally usedused forfor surfacesurface micromachiningmicromachining SurfaceSurface MicromachiningMicromachining AdditiveAdditive processesprocesses BulkBulk MicromachiningMicromachining SubractiveSubractive ProcessProcess DividingDividing lineline cancan becomebecome veryvery blurryblurry StandardStandard ICIC ProcessesProcesses Source: CWRU Source: Jaeger StandardStandard ICIC ProcessesProcesses Source: Photolithography Jaeger StandardStandard ICIC ProcessesProcesses 1) Deposit/Grow Thin Films • Sputtering • Evaporation • Thermal Oxidation • CVD • Spinning • Epitaxy StandardStandard ICIC ProcessesProcesses 2) Pattern Thin Films • Lithography • Etching Techniques (wet, dry, RIE) StandardStandard ICIC ProcessesProcesses 3) Introduce Dopants (to form electrically-active regions for diodes, transistors, etc.) • Thermal Diffusion • Ion Implantation MicromachiningMicromachining ProcessesProcesses Bulk Micromachining • wet vs dry • isotropic vs anisotropic • subtractive process Bulk Micromachining MicromachiningMicromachining ProcessesProcesses Bulk Micromachining Source: Madou Source: Maluf Source: Maluf MicromachiningMicromachining ProcessesProcesses Deep Reactive Ion Etching (DRIE) • high density ICP plasma • high aspect ratio Si structures • cost: $500K Source: LucasNova Source: STS Source: STS Source: AMMI MicromachiningMicromachining ProcessesProcesses Wafer-Level Bonding • glass-Si anodic bonding • Si-Si fusion bonding • eutectic bonding • low temp glass bonding Source: Maluf Source: EV MEMSMEMS ExamplesExamples Pressure Sensor (conventional) Source: NovaSensor 60 ) 50 V (m 40 e g a t l 30 o V t 20 tpu u O 10 0 0 20 40 60 80 100 120 Source: UofL Pressure (PSI) MicromachiningMicromachining ProcessesProcesses Surface Micromachining • additive process • structural & sacrificial layers Source: Sandia MUMPS Process (Micromotor) MicromachiningMicromachining ProcessesProcesses LIGA (lithographie, galvanoformung, abformtechnik) • uses x-ray lithography (PMMA), electrodeposition and molding to produce very high aspect ratio (>100) micro- structures up to 1000 um tall (1986) Source: Madou Source: Kovacs LIGA MEMSMEMS ExamplesExamples Micro-structures using LIGA Source: UW MicromachiningMicromachining ProcessesProcesses Poor Man’s LIGA • uses optical epoxy negative-resist (SU-8) developed by IBM to produce high aspect ratio micro-structures (1995) UofL Micro-reaction wells: 150 um wide, 120 um tall, 50 um wall thickness Source: Maluf MEMSMEMS ExamplesExamples Micromotors Source: MIT and Berkeley MEMSMEMS ExamplesExamples Optical MEMS (MOEMS) Source: NIST, Simon Fraser, UCLA, and MCNC MEMSMEMS ExamplesExamples Pressure Sensor (ultra-miniature) Source: NovaSensor MEMSMEMS ExamplesExamples Lab-on-a-Chip Systems • separation • dilution • mixing and dispensing • analysis Source: Caliper MEMSMEMS ExamplesExamples Micromachined Tips for FEDs and AFMs Source: Micron (?) Source: IBM MEMSMEMS ExamplesExamples Neural Probes Source: Mich (K. Wise) MEMSMEMS ExamplesExamples Neural Interface Chip Source: Stanford MEMSMEMS ExamplesExamples Micro-Grippers Source: Berkeley MEMSMEMS ExamplesExamples Micro-Tweezers Source: MEMS Precision Instruments MEMSMEMS ExamplesExamples Optical MEMS (MOEMS) Source: IMC (Sweden), Maluf and TI MEMSMEMS ExamplesExamples Accelerometers Sources: Analog Devices, Lucas NovaSensor, and EG&G IC Sensors MEMSMEMS ExamplesExamples Channels, Nozzles, Flow Structures, and Load Cells Source: EG&G IC Sensors Relative tolerances: Si µ-machining is not good precision machining Scaling in MEMS Linear extrapolation of length comes easy to us We are quickly at a loss though when considering the implications that shrinking of length has on surface area to volume ratios (S/V) and on the relative strength of external forces (actuator mechanisms) Some examples of effects of S/V: Both very large and very small mamals (i.e. animals with constant body T) have difficulty surviving :i.e. there are few niches for the large animals and there is too much heat loss for small animals (heat loss ~ L2 and heat generation (through eating) is ~ L3)---insects avoid this problem by being cold blooded 3 1 3 Capillary tubes (L vs. L ): weight scales as L and surface tension as L Scaling Laws Nature seems to favor small e.g. Insects are very well adapted: As the scale of structures decreases so does the importance of phenomena that vary with the largest power of the linear dimension –Insects walk on water (surface tension supports their mass m) Insects jumps very far (E~mh and muscle for that work is ~m so h is a constant) Faster cooling and heating (cold blooded) Small thermal stresses (Small Biot number i.e. little thermal stress) Scaling Effects Scaling Laws AA MatrixMatrix formalismformalism isis usedused toto describedescribe thethe scalingscaling lawslaws.. ThisThis nomenclaturenomenclature showsshows aa numbernumber ofof differentdifferent forceforce lawslaws inin aa singlesingle equationequation.. InIn thisthis notationnotation,, thethe sizesize ofof thethe systemsystem isis representedrepresented byby aa singlesingle scalescale variablevariable,, L,L, whichwhich representsrepresents thethe linearlinear scalescale ofof thethe systemsystem.. TheThe choicechoice ofof LL forfor aa systemsystem isis aa bitbit arbitraryarbitrary.. TheThe LL couldcould bebe thethe separationseparation betweenbetween thethe platesplates ofof aa capacitor,capacitor, oror itit couldcould bebe thethe lengthlength ofof oneone edgeedge ofof thethe capacitor.capacitor. OnceOnce chosenchosen,, howeverhowever,, itit isis assumedassumed thatthat allall dimensionsdimensions ofof thethe systemsystem areare equallyequally scaledscaled downdown inin sizesize asas LL isis decreaseddecreased ((isometricisometric scalingscaling).). Force Scaling Laws For example, nominally L= 1; if L is then changed to 0.1, all the dimensions of the system are decreased by a factor of ten. A number of different cases are shown in one equation. For example: shows four