COBALT MICROSTRUCTURE BY DC MAGNETRON SPUTTERING

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COBALT MICROSTRUCTURES ARE PREPARED BY DC MAGNETRON SPUTTERING FOLLOWED BY LASER BEAM WRITING AND ION BEAM ETCHING

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COBALT MICROSTRUCTURE BY DC MAGNETRON SPUTTERING

  1. 1. LITHOGRAPHICALLY PATTERNED COBALT MICROSTRUCTURES AND ITS CHARACTERISTICS RAJEEV R. PILLAI   Register No: 071605100010 M.Tech Nano Technology Biotechnology Centre, Department of Nano Technology Anna University
  2. 2. INTRODUCTION <ul><li>Spintronics Laboratory </li></ul><ul><li>Indian Institute of Science </li></ul><ul><li>Bangalore Guide </li></ul><ul><li>Dr. P. S. Anil Kumar </li></ul><ul><li>Assistant Professor </li></ul><ul><li>Department of Physics </li></ul>
  3. 3. Thin Film <ul><li>Thin material layers ranging from fractions of a nanometer to several micrometers in thickness. </li></ul><ul><li>Mechanical strength </li></ul><ul><li>Carrier transportation </li></ul><ul><li>Super conducting transitions </li></ul><ul><li>Magnetic properties </li></ul><ul><li>Optical Properties </li></ul>
  4. 4. Applications <ul><li>Electrical Conductor films </li></ul><ul><li>Optical films </li></ul><ul><li>Decorative films </li></ul><ul><li>Wear resistant coating </li></ul><ul><li>Corrosion resistant films </li></ul><ul><li>Dry film lubricants </li></ul><ul><li>Magnetic films for recording </li></ul>
  5. 5. Thin Film deposition process
  6. 6. PROJECT <ul><li>FABRICATION OF COBALT MICROSTRUCTURE </li></ul><ul><li>& </li></ul><ul><li>CHARECTERISATION </li></ul>
  7. 7. Desired Microstructure
  8. 8. Attractiveness of Cobalt Thin Film <ul><li>It is Ferro magnetic in nature </li></ul><ul><li>Apt for spin-based studies </li></ul><ul><li>Research areas includes spintronics, leading to higher capacity memory devices </li></ul>
  9. 9. Process Involved <ul><li>DC Magnetron Sputtering </li></ul><ul><li>Direct Laser beam writing </li></ul><ul><li>Ion Beam etching </li></ul><ul><li>Atomic Force Microscopy </li></ul><ul><li>MR Measurements </li></ul>
  10. 10. DC Magnetron Sputtering <ul><li>It consist of the following: </li></ul><ul><li>Vacuum system </li></ul><ul><li>Vacuum chambers </li></ul><ul><li>Vacuum pumps </li></ul>Load Lock Spherical Cylindrical Rotary Pump TSP
  11. 11. Experimental Set Up – Cont… <ul><li>Control Unit </li></ul><ul><li>Pressure Gauges </li></ul><ul><li>Transporter Rod </li></ul><ul><li>Targets </li></ul><ul><li>Gas System </li></ul><ul><li>Thickness Monitor </li></ul><ul><li>Substrate (Silicon) </li></ul>Pirani Micro Ion Argon Nitrogen
  12. 12. DC Magnetron sputtering <ul><li>Advantages </li></ul><ul><ul><li>Lower voltage needed to strike plasma. </li></ul></ul><ul><ul><li>Controls uniformity. </li></ul></ul><ul><ul><li>Reduce wafer heating from electron bombardment. </li></ul></ul><ul><ul><li>Increased deposition rate </li></ul></ul>
  13. 13. Sputtering Unit at IIsc
  14. 14.
  15. 15.
  16. 16.
  17. 17. Direct Laser Beam Writing <ul><li>Spin Coating </li></ul><ul><li>Pre-baking </li></ul><ul><li>Laser Writing </li></ul><ul><li>Developing </li></ul><ul><li>Post-baking </li></ul>
  18. 18.
  19. 19.
  20. 20. Ion Beam etching Base Pressure 3.6E-6mbar (250 Hz) Pressure with Argon = 2.6E-4mbar (183 Hz) Cathode filament current 3.19A Beam Voltage 400V Acceleration Voltage 200V Neutraliser filament current 2.79A Discharge Voltage 38V Discharge current = 0.16A Neutraliser emission current 16mA Beam current = 9mA Acceleration current 1mA
  21. 21.
  22. 22.
  23. 23. Atomic Force Microscopy <ul><li>Non – contact mode </li></ul><ul><li>Approach </li></ul><ul><li>Advanced </li></ul><ul><li>Height Profile </li></ul><ul><li>3D scanning </li></ul>
  24. 24.
  25. 25.
  26. 26. MR Measurements <ul><li>The sample is placed on a glass slide and connections are made on the contact pads in the structure using copper wires </li></ul><ul><li>The wires are attached to the sample using silver paste. </li></ul><ul><li>The sample is now loaded on sample holder and connections are made </li></ul>
  27. 27. <ul><li>The sample holder is loaded into the vacuum chamber and using a rotary pump the chamber is evacuated. </li></ul><ul><li>The four connections are labeled as: 1---I+ </li></ul><ul><li>2--I- </li></ul><ul><li>3---V- </li></ul><ul><li>4---V+ </li></ul>
  28. 28. <ul><li>Load the vacuum chamber (with sample inside) in between electromagnets </li></ul><ul><li>Power the electromagnets and give 300 Oe magnetic field to the sample and a constant current of 1m A is applied to it </li></ul><ul><li>Now switch ON the lab view software system display on the computer and set the number of scans =10 and the average time for each scan as 5min </li></ul>
  29. 29. <ul><li>The magnetic field and electric field are parallel to each other and the angle between them is 0  (deg) </li></ul><ul><li>Now increase the magnetic field values and record the change in resistance of the sample using the scanning lab view software. </li></ul><ul><li>Similarly do the scanning for the different angles starting from 0  to 360  . </li></ul>
  30. 30. <ul><li>Plot the different data points in the scanned data using origin graph software. </li></ul><ul><li>Now calculate the %MR (magneto resistance) values for each angle from the scan plot. </li></ul><ul><li>Finally plot a graph between angle between the magnetic field and electric current (  ) and the %MR obtained for each value of (  ) using origin software. </li></ul><ul><li>Thus AMR of the Cobalt microstructure can be observed from the graph. </li></ul>
  31. 31.
  32. 32. RESULTS: Co target - before & after sputtering
  33. 33. Cobalt microstructure Cobalt microstructure
  34. 34.
  35. 35.
  36. 36.
  37. 37. Result & Conclusion <ul><li>A thin film of cobalt was deposited on a silicon substrate by DC magnetron sputtering technique and a microstructure of cobalt with our desired dimensions was fabricated on this thin film using Direct laser beam technique followed by ion beam etching. The microstructure’s structural characterization was done by optical and atomic force microscopy. </li></ul>
  38. 38. <ul><li>Finally, its magnetoresistive properties were studied and its resistance was found to be varying with the angle between magnetic field and current and have maximum values of MR when both the current and magnetic field are in same direction confirming it to be showing AMR. </li></ul>
  39. 39. Thank You

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