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Superconformal Film Growth

Superconformal Film Growth. T.P. Moffat, D. Wheeler, C. H. Lee, D. Josell Materials Science and Engineering Laboratory. Superconformal electrodeposition. Objective:

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Superconformal Film Growth

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  1. Superconformal Film Growth T.P. Moffat, D. Wheeler, C. H. Lee, D. Josell Materials Science and Engineering Laboratory

  2. Superconformal electrodeposition Objective: Void and seam-free filling of recessed surface features with metals and alloys for passive 3-D conductors or active magnetic elements. Advantages: Build interconnected or isolated 3D structures that are easily integrated with existing platforms associated with CMOS, MEMS, etc New avenue for device manufacture & the possibility of novel architectures otherwise unavailable with existing processes

  3. Superconformalor “Bottom-up” Filling of Submicron Features As a function of TIME As a function of ASPECT RATIO

  4. ????? How does superconformal film growth occur ????? ?? How general is the phenomenon ?? 1.Curvature Enhanced Accelerator Coverage Model Quantitatively Explains Superfilling of Submicrometer Features Electrodeposition of Copper, Silver and Gold Chemical Vapor Deposition of Copper Quantitative Model of “Brightening” 2. Transient Inhibition Breakdown Model Explains Superfilling of Nickel and related Ni-Co-Fe alloys

  5. The Important Role of Surface Chemistry: Competitive and co-adsorption of specific surfactants can lead to strong acceleration or inhibition of the metal deposition rate. No copper deposition on Au-S-(CH2)3-CH3 Catalyzed copper deposition on Au-S-(CH2)3-SO3- 10 mm

  6. Curvature Enhanced Accelerator Coverage Mechanism • Dilute catalyst “floats” on the surface during metal deposition. • Local catalyst coverage increases as local area decreases. • Converse also true. • Local metal deposition rate increases with catalyst coverage. CEAC is most important when changes in adsorbate coverage due to area change dominates adsorption or consumption processes!!

  7. Superfilling Trenches with Copper CEAC Simulation and Experiment 70 s 50 s 40 s 35 s 30 s Copper deposition in an electrolyte containing 6 uM SPS 88 uM PEG 1mM NaCl 25 s

  8. Ag has a higher conductivity than Cu Ag Superfilling from a KSeCN-KAg(CN)2-KCN Electrolyte Deposition Time AR Derivitization Time: 10 s (fixed amount of adsorbed catalyst)

  9. Au is the metallization of choice in GaAs technology Pb catalyzed Au superfilling from a KAu(CN)2-KCN-KOH

  10. 3-D metallization for ULSI and MEMS NIST offers measurements and metrology for understanding and optimizing superconformal electrodeposition of Cu, Ag and Au for use as conductors. ITRS 10

  11. What about “active” magnetic materials? • Applications of ferromagnetic materials (Ni, Co, Fe) - Magnetic recording heads and recording media - Magnetic sensors, actuators, motors for MEMS devices - Memory devices (MRAM, race track memories) and bio-medical systems • However conventional fabrication of magnetic structures uses a inherently 2-D process that is difficult to combine with CMOS LIGA process for building 3-D structures. • NIST has developed a deposition process that allows void-free filling of recessed features with nickel and related iron group alloys that can be easily integrated with existing Damascene processes and related tool sets. Electrodeposition 11

  12. Superfilling of Ferromagnetic Materials - Easy to realize various 3-D magnetic structures - Suitable for integrationwith existing CMOS fabrication processes • Damascene process for ferromagnetic structures 12

  13. Collaboration Opportunities • NIST has developed a wide range of measurements and modeling capabilities for exploring and optimizing superfilling processes. • Intellectual Property: “Superconformal Electrodeposition of Ni-Fe-Co Magnetic Alloys” Provisional Patent Application filed 1/25/2008 Serial # 61/023,593 “Superconformal Metal Deposition Using Derivatized Substrates” Provisional Patent Application filed 5/23/2003 Serial # 10/444,060

  14. For further information please contact: Thomas P. Moffat Materials Science and Engineering Laboratory National Institute of Standards and Technology Bldg 224, B166 Mail Stop 8551 Gaithersburg, Md 20899 thomas.moffat@nist.gov

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