1 / 55

Design of a compact AFM scanner

Design of a compact AFM scanner. Compact, high speed and high accuracy AFM scanner K. J. Kamp June 26, 2013 Committee: Prof . Ir. R.H. Munnig Schmidt Dr. Ir. S. Kuiper Dr. Ir. J. L. Herder Dr. Ir. J. F. L. Goosen. Outline. Introduction to Atomic Force Microscopes (AFM)

Download Presentation

Design of a compact AFM scanner

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Design of a compact AFM scanner Compact, high speed and high accuracy AFM scanner K. J. KampJune 26, 2013 Committee: Prof. Ir. R.H. MunnigSchmidt Dr. Ir. S. Kuiper Dr.Ir. J. L. Herder Dr. Ir. J. F. L. Goosen

  2. K. J. Kamp Design of a compact AFM scanner Outline • Introduction to Atomic Force Microscopes (AFM) • Research questions • Requirements and specifications • Concept 1 • Concept 2 • Detailed Design • Conclusion

  3. K. J. Kamp Design of a compact AFM scanner • Introduction • Research Questions • Requirements specifications • Concept 1 • Concept 2 • Detailed Design • Conclusion Introduction

  4. K. J. Kamp A compact AFM scanner Introduction The atomic force microscope (AFM) • Basic operation principle • Probe tip attached to a cantileveris scanned over a sample • Cantilever deflects due to the atomic forces • The cantilever deflectionmeasures the surface topography

  5. K. J. Kamp A compact AFM scanner Introduction The AFM scannerLateral scanning • Triangularpattern • Constant tip speed x z y

  6. K. J. Kamp A compact AFM scanner Introduction The AFM scannerVertical scanning • Feedback loop • Cantilever deflection signal minimal • The probe tip tracks the topography DOI wafer AFM measurement

  7. K. J. Kamp A compact AFM scanner Introduction AFM system specifications • Surface area (x,y) <15mm x 15mm • Measurement range (x,y,z) >10 x 10 x 2 microns • Imaging time < 1 s • Measurement uncertainty < 1 nm

  8. K. J. Kamp A compact AFM scanner Top View Introduction z y Concept 1:The tripod scanner x Sensor Sensor Actuator 3 u3 Actuator 1 Actuator 2 u2 u1 Sensor

  9. K. J. Kamp A compact AFM scanner • Introduction • Research Questions • Requirements specifications • Concept 1 • Concept 2 • Detailed Design • Conclusion Research Questions

  10. K. J. Kamp A compact AFM scanner Research questions • How do the specifications of the AFM system translate to the requirements of the AFM scanner? • Does the first scanner concept meet the requirements? • Does the second scanner concept meet the requirements? • Is the second scanner concept valid as a real world design?

  11. K. J. Kamp A compact AFM scanner • Introduction • Research Questions • Requirements specifications • Concept 1 • Concept 2 • Detailed Design • Conclusion Requirements

  12. K. J. Kamp A compact AFM scanner Requirements Research question 1:How do the specifications of the AFM system translate to the requirements of the AFM scanner? • Measurement uncertainty < 1 nm  Translate to scanner roll angles • Imaging time < 1 s  Translate to scanner resonance frequencies

  13. K. J. Kamp A compact AFM scanner Requirements Measurement uncertainty to roll angle • Misalignment sensors and probe tip: 0,5 mm • Scanner will rotate (roll angle) → This causes an Abbeerror (measurement uncertainty)

  14. K. J. Kamp A compact AFM scanner Requirements Abbe error • Platform roll angle φ • Sensor offset δ • Abbe error: eabbe = δ tan(φ)Assumptions: δ = 0,5 mmeabbe < 1,0 nm φ < 2 microrad

  15. K. J. Kamp A compact AFM scanner Requirements Imaging time to resonance frequencies • Lateral resonance frequency > 10 kHz Triangular wave frequency content • Vertical resonance frequency > 30 kHzTracking error, scanning speed x z y

  16. K. J. Kamp A compact AFM scanner • Introduction • Research Questions • Requirements specifications • Concept 1 • Concept 2 • Detailed Design • Conclusion Concept 1

  17. Design of a compact AFM scanner Concept 1 Analysis of the tripod concept Kinematics related to scanner stroke Statics related to scanner roll angles (Abbe error) Dynamics related to scanner resonance frequencies

  18. K. J. Kamp A compact AFM scanner Concept 1 z y Kinematics analysis Required stroke: 10 x 10 x 2 microns • Relation is found between x, y, z (platform position) u1, u2, u3 (actuators) x u3 u1 u2

  19. K. J. Kamp A compact AFM scanner Concept 1 Example • Ten scan lines 10 x 10 microns • Actuatordisplacement~ 6 microns • Mechanical amplification 10 / 6 = 1.66

  20. K. J. Kamp A compact AFM scanner Concept 1 z y Scanner roll angle • Hinges are not perfect • Lateral motion will cause the scanner to roll x u3 u1 u2

  21. Titel van de presentatie Concept 1 2D Statics analytical model

  22. K. J. Kamp A compact AFM scanner Concept 1 Main cause of AFM scanner roll • Stiffness ratio between longitudinal and lateral stiffness of a rod Normalized stiffness ratio []

  23. K. J. Kamp A compact AFM scanner Concept 1 Statics • Flexure notch hinges • Increase longitudinal to lateral stiffness ratio • Decreases the roll angle

  24. K. J. Kamp A compact AFM scanner Concept 1 Statics FEM analysis • 3D FEM model

  25. K. J. Kamp A compact AFM scanner Concept 1 Statics FEM results • u1 = 5 microns • x = 5 microns • φ = ~ 460 microrad

  26. K. J. Kamp A compact AFM scanner Concept 1 Statics FEM results • Roll angle is lower • φ = ~ 360 microrad

  27. K. J. Kamp A compact AFM scanner Concept 1 Statics FEM results • Circular notch hinge • Roll angle even lower • φ=~ 60 microrad

  28. K. J. Kamp A compact AFM scanner Concept 1 Dynamics • First four resonances:

  29. K. J. Kamp A compact AFM scanner Concept 1 FEM Modal analysis • Eigenmode results Yaw9,8 kHz Lateral9,3 kHz Roll42 kHz Vertical 48 kHz

  30. K. J. Kamp A compact AFM scanner Concept 1 SummaryCan the requirements be met? • Trade-off low roll angle vs. high resonance frequencies • Low roll angles require a high stiffness ratio (low lateral stiffness) • High resonance frequencies require high stiffness overall Conclusion: The individual requirements can not all be met. Concept 1 is not feasible

  31. K. J. Kamp A compact AFM scanner • Introduction • Research Questions • Requirements specifications • Concept 1 • Concept 2 • Detailed Design • Conclusion Concept 2

  32. K. J. Kamp A compact AFM scanner Concept 2 • Orthogonal scanning conceptLateral motion Side view Top view Probe tip Sensor Sensor Actuator Actuator

  33. K. J. Kamp A compact AFM scanner Concept 2 • Orthogonal scanning conceptVertical motion Side view Top view Probe tip Sensor Sensor Actuator Actuator

  34. K. J. Kamp A compact AFM scanner x Concept 2 Kinematics Lateral stroke:mechanical amplification = lever ratio b to a ulever b a

  35. z K. J. Kamp A compact AFM scanner φ x uφ L ux uφ Concept 2 uz K1 ux uz Statics analysis Analytical model adapted to the orthogonal concept L2 K2 K2 ulever

  36. K. J. Kamp A compact AFM scanner Concept 2 Analytical model and FEM analysis • Pure lateral input (no lever)ux = 5 microns • Analytical model: φ = 21,7 microrad • FEM resultφ = 22,9 microradThe roll angle φ is positive

  37. K. J. Kamp A compact AFM scanner uφ ux uz Concept 2 b a Including the lever • Input uxresults in a positive roll angle • Input uφresults in a negative roll angle ulever positive negative ux uφ

  38. K. J. Kamp A compact AFM scanner Concept 2 • Analytical model and FEM results • The length of the vertical rods is varied: • The roll angle shifts from negative to positive

  39. K. J. Kamp A compact AFM scanner Concept 2 • The analytical model is used to find zero roll angle Vertical rod length [m]

  40. K. J. Kamp A compact AFM scanner Concept 2 Resulting roll angle Final iteration L1 = 3,0 mmL2 = 4,0 mm ulever= 10 microns x = 4,9 microns Roll angleφ = -0,63 microrad

  41. K. J. Kamp A compact AFM scanner Concept 2 Lateral: Dynamics FEM modal results Lateral eigenmodes(x,y):~12,3 kHzVertical mode (z): ~36,5 kHz Vertical:

  42. K. J. Kamp A compact AFM scanner Concept 2 Summary • The orthogonal scanner concept meets all the requirements • The stroke of 10 x 10 x 2 microns can be achieved • The roll angle is ~ 0,64 microrad • The resonance frequencies are 12,3 kHz lateral 43,4 kHz vertical

  43. K. J. Kamp A compact AFM scanner • Introduction • Research Questions • Requirements specifications • Concept 1 • Concept 2 • Detailed Design • Conclusion Detailed design

  44. K. J. Kamp A compact AFM scanner Detailed design Component selection • Piezo actuators • Triangulation sensors • AFM chip holder

  45. K. J. Kamp A compact AFM scanner Detailed design Piezo actuators • PI (PhysikInstrumente) • 5 x 5 x 9 mm for vertical motion • 3 x 3 x 13,5 mm for lateral motion

  46. K. J. Kamp A compact AFM scanner Detailed design Triangulation sensors • Lion Precision capacitive sensors

  47. K. J. Kamp A compact AFM scanner Detailed design AFM chip holderBrukerDAFMCH probe holder Piezo holder measures 4 x 5 mm at the base.

  48. K. J. Kamp A compact AFM scanner Detailed design Probe holder Final design overview • Outer dimensions (x,y): 26 x 26 mm Lever Sensor Piezo actuator

  49. K. J. Kamp A compact AFM scanner Detailed design Cross-section view (no piezo actuators)

  50. K. J. Kamp A compact AFM scanner Detailed design

More Related