Design and Fabrication of a Multifunctional Scanning Probe

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2008 ASPE Annual Meeting

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Design and Fabrication of a Multifunctional Scanning Probe

  1. 1. DESIGN AND FABRICATION OF A MULTIFUNCTIONAL SCANNING PROBE WITH INTEGRATED TIP CHANGER FOR FULLY AUTOMATED NANOFABRICATION Curtis R. Taylor1 and Kam K. Leang2 1Department of Mechanical and Aerospace Engineering University of Florida, Gainesville, FL 2Department of Mechanical Engineering University of Nevada-Reno, Reno, NV 23rd ASPE Annual Meeting October 19-24, 2008, Portland, Oregon
  2. 2. Outline 1. Need for Probe-based Nanoscale Tools • Challenges for nanoscale fabrication • Advantages of probe-based tools • Limitations and challenges of probe-based tools 2. Automated Tip Changing System Concept • MEMS Thermally-Actuated Gripper and Integrated Proximity Sensor • Advantages/Benefits/Novelty • Key Applications Enabled by System 3. Design, Modeling, and Fabrication Results • Cantilever Design • Dynamic Modeling • Coupled Electro-Thermo-Mechanical Modeling • Fabrication Process • Fabrication of Prototype 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 2
  3. 3. Nanoscale Fabrication Tools • TOP DOWN Fab Tools Non-Planar Surface Features – Mesas, Trench, Line and Hole FIB geometries via: – E-beam lithography – FIB sculpting – Micromachining/fabrication • BOTTOM UP Fab Processes Strain and Chemical Surface Modification MicroFab – Heteroepitaxial Strain – Ion Implantation – Self-Assembly Self-Assembly Expensive Tools require large fabs/cleanrooms Complex Processes 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 3
  4. 4. Advantages of Fabrication Via Probe Tip Tools IBM’s Probe-based Memory Technology >1 Tb/in2 T. Kenny, 2007 Arrays of 1,000s of probes can be used to: manipulate, pattern, machine, scribe, write, deposit, and engineer material surfaces Mirkin et. al., at the nanoscale with: Angew. Chem. , 2006 (45), 7720 <1 nm resolution on diverse materials without costly cleanroom processes 55,000 replicas (88 million nanofeatures) over 1 cm2 in less than 30 minutes 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 4
  5. 5. Limitations and Challenges for Probe Tip NanoManufacturing 1. Tip Wear 1. 2. Cross-contamination 3. Throughput • single tip • > 5 minutes to change tip new tip worn tip 3. nanolithography tip 2. fouled tip nanomachining tip 10 um debris r ~ 10 nm • 50+ different probe tips and microscopy modes - no integrated platform/ manual tip change produces slow throughput 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 5
  6. 6. Probe Tip Changer For Fully Automated Nanofabrication Funded by NSF CMMI Grant #0726778 To address the critical issues of throughput, tip wear, APPLICATIONS: repeatability, scalability, and limited functionality of probe-based nanofabrication • Nanoscale Rapid Prototyping • Desktop Nanofactory • Enhance throughput • Hybrid Printing of Nanostructures • Expand functionality • Enable fully automated nanofabrication • Provide method for scalability and robust fabrication 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 6
  7. 7. Tip Changing System Concept 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 7
  8. 8. Cantilever Design Specifications • Design Specs and Requirements – compatible with existing AFMs – actuation – stiffness – resonant frequency – gripping force and tip stability • Thermally-Actuated Gripper – High current density in smaller arm results in higher heating and thermal expansion. 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 8
  9. 9. Thermally-Actuated Cantilever Design Concepts V-flexure flexures Single Flexure Multiple Flexure V-Flexure High current density in smaller arm results in higher heating and thermal expansion 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 9
  10. 10. Static/Dynamic Modeling 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 10
  11. 11. Analytical Model of Cantilever Thermal-Actuation Huang et. al., J. Micromech. Microeng., 9 (1999) 64-70  dT  2  dT  T − Ts −kA   + J ρ AΔx = −k p A   + SΔxw  dx  x  dx  x + Δx RT joule heating conductive heat transfer ( ΔL = α L T − Tref ) δ deflection 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 11
  12. 12. FEA Electro-Thermal-Mechanical Model COMSOL Q T δ Multiphysics joule heating temperature deflection electric potential distribution, conduction, thermal strain, Hooke’s current density convection heat law, deflection transfer, temperature r r h σ = Dε Governing J = σE Equation r r −∇gk∇T ) = Q + ( (Text − T ) dA −∇g = F σ Jg = Q E Constants V, ρ(T ) k, h α ,Ε B.C.s V (0) = 0 T (0) = T (L) = 298K δ (0) = δ (L) = 0 V (L) = V0 heat flux on other boundaries 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 12
  13. 13. Comparison of FEA and Analytical Model Same dimensions and parameters used in Huang model Results of ‘multiphysics’ FEA model in agreement with analytical model *Note: FEA model includes convective contribution 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 13
  14. 14. Application of FEA Model to Design of Cantilevers Q T joule heating temperature δ deflection electric potential conduction, thermal strain, distribution, current convection heat Hooke’s law, density transfer, temperature deflection 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 14
  15. 15. FEA Modeling of Design Concepts V-flex fails by contact of hot arms max ~ 3 um 1200 K = thermal max ~ failure 2V single multiple flex flex 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 15
  16. 16. Fabrication of Prototype • 3 mask, SOI process 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 16
  17. 17. Prototype Fabrication • Rapid Prototyping of Cantilever concept has been performed • Prototype of Silicon probe fabricated Future Work • Testing • Optimization • Modular Tip Design and Fab 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 17
  18. 18. Summary 1. Need for Probe-based Nanoscale Tools • Sub 1 nm resolution • Low cost versus energetic beam tools and bottom up processes 2. Automated Tip Changing System Concept • Addresses key issues of tip wear, cross-contamination, and throughput • MEMS Thermally-Actuated Gripper and Integrated Proximity Sensor • Key Applications Enabled by System • Nanoscale Rapid Prototyping • Nanofactory 3. Design, Modeling, and Fabrication Results • Prototype cantilever designed • Coupled Electro-Thermo-Mechanical model developed and validated • Fabrication of prototype 23rd ASPE Annual Meeting, Oct. 19-24, 2008 Slide 18

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