B y : B i t e w D i n k e H u g o F e r r e r E n e e 4 1 6 D r . G h o d s s i LIGA LithographyDefinition of LIGA LIGA is a German acronym that stands for Lithographie, Galvanoformung and Abformung. When translated it means lithography, electroplating and molding.Background LIGA is a three stage micromachining technology used to manufacture high aspect ratio microstructures. Originally LIGA technology was researched in Germany in order to be used for the separation of uranium isotopes. Henry Guckel of the University of Wisconsin brought LIGA technology to the USA.Background Two main types of LIGA Technology: X-ray LIGA and Extreme Ultraviolet (EUV) LIGA. X-ray LIGA can fabricate with great precision high aspect ratio microstructures. EUV LIGA can fabricate lower quality microstructures.LIGA Process LIGA is a hybrid fabrication technique The LIGA Process Lithography Electron beam lithography Focused ion beam lithography Optical and exciter laser lithography Deep X-ray lithography using synchrotron radiation Electroplating metalized layer (seed layer) Molding Machining process to remove overplated metal regionFunction of LIGA To produce high aspect ratio To manufacture 3-D microstructures from a wide variety of materials Figure1: 3-D microstructureLithography Deep X-ray lithography Historically chosen as a source for LIGA process superior to optical lithography Utilize short wavelength very large depth of focus Synchrotron Light Source maintains energy anywhere from 106to 109 eV • Figure2: Synchrotron Light Source setupDeep X-ray Lithography techniques Step 1: -Deposition of Adhesion -Seed layer Step 2: -resist coating Step 3: -expose the PMMA resist Step 4: -development of the exposed resistElectroplating and Micro molding techniques Electroplating is a process to fill in the voids between the polymeric features. Step 5: -metal plating Step 6: -removal of the remaining resist Molding is process of machining the overplated region filling the microstructure Step 7: -filling and ejection the microstructureMORE about LIGA Technology Fig. Outline of the LIGA technology. (a) Photoresist patterning, (b) electroplating of metal, (c) resist removal, and (d) molded plastic components.Advantages & Disadvantage Large structural height and sidewall properties. Thickness ranging from 100-1000 μm. Spatial resolution. High aspect ratios. EUV LIGA is a cheaper alternative. X-ray LIGA is expensive due to the equipment required. Slow process. Complicated process. Difficulty transitioning from research to production.Applications MEMS Components Sensors Actuators Trajectory Sensing Devices Mass Spectrometers Microoptical ComponentsQuestions ?References C. K. Malek. V. Saile. (2004). Applications of LIGA Technology to Precision Manufacturing of High-aspect-ratio Micro-components and -systems: a Review. Microelectronics Journal [Online]. Available: http://www.sciencedirect.com/science?_ob=MiamiImageURL&_cid=271437&_user=9 61305&_pii=S0026269203002957&_check=y&_origin=&_coverDate=29-Feb- 2004&view=c&wchp=dGLbVlk- zSkWz&_valck=1&md5=82bfcbfb24453b7ea7383a12725e6a32&ie=/sdarticle J. Zhang. (2002, December). LIGA MOLD INSERT FABRICATION USING SU-8 PHOTORESIST. etd.lsu.edu [Online]. Available: http://etd.lsu.edu/docs/available/etd-1108102-101121/unrestricted/Zhang_thesis.pdf O. O. Sandoval Gonzalez. A Fabrication Technology for High –Aspect Ratio Microstructures. Sandoval-Gonzalez [Online]. Available: http://www.sandoval-gonzalez.com/10_liga.pdf V. Saile. (2009). Introduction: LIGA and Its Application. Verlag GmbH & Co.[Online]. Available:
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