Resolution Limits of CA Resists – Low activation Energy ... - IDEMA

Functional Materials for Advanced PatterningRobert D. AllenBusiness Unit or Product NameIBM Almaden Research Center© 2003 IBM Corporation

IBM ResearchResists/Materials for Advanced Patterning• Trends in Lithography and Materials Implications• Chemical Amplification----unlocking the potential of lithography throughmaterials and chemistry• 193nm Lithography---materials challenges, amazing extendibility• Immersion• Extending Immersion (time permitting)– High Index– Double Patterning• Post-immersion lithography candidates– EUV– EB– Nanoimprint• The Potential of Lithography-directed Self AssemblyBob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchCA Resist BasicsHistory of Chemically Amplified (CA) Resists• Ito, Willson and Frechet (IBM San Jose) invented CA resists in theearly 1980s. Initial focus was on very high speed resists for DUV(254nm lamp-based scanners).• TBOC resist was generation 1 (ca. 1984)• First manufacturing in IBM for 4 Mb DRAM in mid 1980s• IBM developed 2 nd generation positive resists (APEX, APEX-E). Stillin use today! (World-wide adoption for 0.25 micron lithography)• Several Generations of DUV Lithography followed (thanks to IBM’sESCAP) (1990’s)—led to acceleration of Moore’s law)• 193nm resists followed (IBM/Fujitsu) (late 90’s)• Extension of 193nm via Immersion lithography (now!)• What is next?Bob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchCA Resist BasicsChemistry of Chemically Amplified Resists—revolutionary change!+SX -hνH +X -exposepost-expose bakeH +( CH -CH )2heat+ + deprotection + CO 2+ H +productsOOxOnonpolar( CH -CH )2OHpolarxdevelopBob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchFunctional Polymers for PatterningESCAP—the prototype in functional materials designxOyOx y zOOHiroshi ItoIBM FellowOH• Dissolution control• Adhesion• etch resistance• high TgOHProperty control knobCA switching groupAcrylic Ester/Phenolic Resist: A breakthrough in resist designSimilar design concepts practiced in 193nm litho, EUV, EBBob Allen - DISKCON© 2006 IBM Corporation

IBM Research193nm Lithography Materials• Alicyclic Acrylic Polymers (nonphenolic)– Etch resistance and developmentproperties were difficult to achieve– Explosion in High PerformanceMaterials and processes helped toextend 193nm lithography to sub-40nmHP resolution.OOOOOO– Materials hybridized from 157nm andDUV lithography helped enableimmersion lithographyORnOF 3 C CF 3OHBob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchImmersion MaterialsResist/topcoat/fluid interfaces in I-lithographybottom elementwaterEvaporationtemp, precipairpermeationparticlesbubblessurface energyaminecontaminationresist componentextractiontopcoatresistintermixingBARCsubstrateMany interfaces, all important, some more than others!Bob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchBase-soluble TopcoatSolutions beyond conventional topcoatsGraded Topcoat*surface-activeadditive in topcoatTopcoat-free Resistsurface-activeadditive in resistTopcoat-free Resistmodified resist +low-leaching PAGBenefits PerformanceResistWaferLow extractionModerate RCAGood performanceWell establishedLow extractionModerate-High RCAHigher CAs possibleLower fluorine content(less expensive)Low extractionVery high RCAFewer process stepsVery high RCAsNo need to modify resistExtraction dependentupon PAG designModerate RCAFewer process stepsOnly one materialLimitationsReceding CA limitedby acidic groupsExtra process stepsReceding CA limitedby acidic groupsExtra process stepsAdditive design crucialfor low defectivityUses specialized PAGsModify resist to increaseRCABob Allen - DISKCON* Same Concept as IBM’s Graded BARC© 2006 IBM Corporation

IBM ResearchAdditive approach is more effective in topcoat-free resistsGraded topcoatTopcoat-free resistTopcoatResistWafer▪ Must dissolve 100+ nm▪ Need many acidic groups for dissolution▫ Increase hysteresis▫ Lower receding contact angle▪ Must dissolve ~2 nm of material▪ Can rely on underlying photoacid to▫ Generate acidic groups where needed▫ After PEB!hνOxOOR fOyOR fxOOOyH +OR fxOHOOyF 3 C CF 3OHSanders et al. Proc. SPIE, 2008.Bob Allen - DISKCONHydrophobicAcidic group for dissolution(exposed regions)© 2006 IBM Corporation

IBM ResearchHFA groups can increase developer wettingxyxyOOOOOOOORR acid-labileF 3 C CF 3R acid-labileF 3 C CF 3OHTilting drop contact anglesWith fluoroalcohol groupsNo fluoroalcohol groupswaterθ recθ adv0.26 N TMAHSanders, Microlithography World, 2007.Fluoroalcohol groups increase hysteresis the least amongst acidic groupsBob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchPotential Successors to 193nm lithography• EUV– Tooling challenges, high speed resists required– Sensitivity, Resolution and LER need to be achievedsimultaneously• EB– Tooling challenges, high speed resists required– Sensitivity, Resolution and LER need to be achievedsimultaneously• Imprint– Tooling challenges, template challenges– Throughput, defectivity, learning requiredBob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchDirected Polymer Self-assembly (DSA)Definition:Use lithographically defined prepatterns to directed polymer self-assemblyLithographicallydefinedprepatternsPolymer self-assemblyChemical patterns+Topographical patterns• Well-defined dimension.• Self-healing.• Compatible with current litho toolingChallenges:Develop materials and process for litho-friendly directed self-assemblyBob Allen - DISKCON© 2006 IBM Corporation

IBM ResearchIntegration Materialsan example of litho-friendlyintegration materialsDSA MethodsTripling QuadruplingP resist= 85 nm P resist= 115 nmxycrosslinkablegroup Provide interface betweenSA and litho materials Compatible with standardlitho process and materialsJ. Y. Cheng, D. P. Sanders, H. -C. Kim, L. K. Sundberg,SPIE Proceeding, 6921, 692127 (2008)P SA= 28.3 nmP SA= 28.8 nmSelf-assembly Materials Materials for scaling Materials for clean up (self-healing)Bob Allen - DISKCON© 2006 IBM Corporation