Wet and Dry Etching湿法和干法刻蚀.ppt

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1、NANO-MASTER,INC.WetandDryEtching湿法和干法刻蚀NANO-MASTER那诺-马斯特中国有限公司吴运祥2017年8月16日NANO-MASTER,INC.各向同性和各向异性Whenamaterialisattackedbyaliquidorvaporetchant,itisremovedisotropically(uniformlyinalldirections)oranisotropicetching(uniformityinverticaldirection).Thedifferencebetweenisotro

2、picetchingandanisotropicetchingisshowninFigure1.Materialremovalrateforwet-etchingisusuallyfasterthantheratesformanydryetchingprocessesandcaneasilybechangedbyvaryingtemperatureortheconcentrationofactivespecies.NANO-MASTER,INC.湿法刻蚀Synonyms:chemicaletching,liquidetching湿法刻蚀定义：W

3、etetchingisamaterialremovalprocessthatusesliquidchemicalsoretchantstoremovematerialsfromawafer.Thespecificpattersaredefinedbymasksonthewafer.Materialsthatarenotprotectedbythemasksareetchedawaybyliquidchemicals.Thesemasksaredepositedandpatternedonthewafersinapriorfabrications

4、tepusinglithography.[2]Awetetchingprocessinvolvesmultiplechemicalreactionsthatconsumetheoriginalreactantsandproducenewreactants.Thewetetchprocesscanbedescribedbythreebasicsteps.(1)NANO-MASTER,INC.湿法刻蚀Diffusionoftheliquidetchanttothestructurethatistoberemoved.(2)Thereactionbe

5、tweentheliquidetchantandthematerialbeingetchedaway.Areduction-oxidation(redox)reactionusuallyoccurs.Thisreactionentailstheoxidationofthematerialthendissolvingtheoxidizedmaterial.(3)Diffusionofthebyproductsinthereactionfromthereactedsurface.各向异性的湿法刻蚀：Liquidetchantsetchcrystal

6、linematerialsatdifferentratesdependinguponwhichcrystalfaceisexposedtotheetchant.Thereisalargedifferenceintheetchratedependingonthesiliconcrystallineplane.NANO-MASTER,INC.湿法刻蚀Inmaterialssuchassilicon,thiseffectcanallowforveryhighanisotropy.Someoftheanisotropicwetetchingagents

7、forsiliconarepotassiumhydroxide(KOH),ethylenediaminepyrocatechol(EDP),ortetramethylammoniumhydroxide(TMAH).Etchinga(100)siliconwaferwouldresultinapyramidshapedetchpitasshowninFigure2a.Theetchedwallwillbeflatandangled.Theangletothesurfaceofthewaferis54.7o.Figure2c-ddepictssca

8、nningelectronmicrographsof(110)-orientedtwo-dimensionalsiliconwallswithmicr