1. Sample Devices for NAIL Thermal Imaging and Nanowire Projects Design and Fabrication Mead Mišić Selim Ünlü

2. Boston University Outline The NAIL and Nanowire Projects NAIL Microscopy and Applications Nanowire Research Objectives Sample Requirements Sample Design and Mask Fabrication Process of Sample Device Manufacturing Conclusion Questions

3. Boston University Problem with the imaging of the Si ICs Metal layer on top of the ICs often make imaging from the substrate an easier option

4. Boston University Conventional Optical Microscopy Refraction reduces sin θ a by a factor of n, so maximum θ a= θ c Total internal reflection θ c = sin -1 (1/n) Resolution Diminished

5. Boston University NAIL Microscopy Using a silicon lens as a coupler Maximum θ a = π/2 Reflection loss at interfaces is minimized. Evanescent wave coupling between the NAIL and substrate Resolution Improved

6. Boston University NAIL Thermal Imaging Tests Imaging test with aluminum wires Without NAIL With NAIL

7. Boston University NAIL Thermal Imaging Resolution No actual real device-like sample imaged yet

8. Boston University The Nanowire Project The goal is to research the conductivity of polymer nanowires for possible integrated sensing applications Drawing of the previous nanowire sample Metal Au Silicon Substrate Nanowire Conductor

9. Boston University Nanowire Sample Proposal Drawing of the proposed device for high throughput measurements of the transport properties of conducting polymer nanowires. Metal Oxide Metal Oxide n+ or p+ Nanowire Conductor

10. Boston University Sample Device Requirements NAIL Requirements Emission lines ranging from 0.8um - 5.0um Width of the spaces between the emission lines ranging from 0.8um - 5.0um To generate a sufficient amount of emission Nanowire Project Requirements Space between implant areas varying Conducting areas to be flat (implanted) Samples to be manufactured on silicon substrate Samples to be manufactured using the same masks

11. Boston University Design Constraints and Decisions 4 inch platform Large metal contact areas P-type pre-doped wafers All ion implants to be n-type Leakage prevention (isolation implant or etch) Leave room for error

12. Boston University The Wafer Mask Layout The picture shows the layout of the devices in CAD using all 5 masks. The masks were manufactured at EPFL in Switzerland.

13. Boston University A Die Layout

14. Boston University Basic Device Dimensions The dimensions indicated are identical in all the devices. 3500um 1500um 1600um 400um 1500 um 100um

15. Boston University NAIL – Periodic Devices Each Device contains 3 implant sections like the one above, with each section containing two samples Samples consist of lines and spaces of equal thicknesses The thicknesses are: 0.8, 1.0, 1.2, 1.5, 2.0, 5.0 um Metal Line Isolation Implant Line

16. Boston University NAIL – Aperiodic Devices Each device contains 3 implant sections like the one above with each section containing 2 samples Samples consist of lines of constant width and variable spacing. The spacing widths are: 0.8, 1.0, 1.2, 1.5, 2.0, 5.0um Metal Line Isolation Implant Line

17. Boston University NAIL - Variable Width Device Device to be used for NAIL Qualification 100um x 100um metal to implant contact Line thicknesses: 0.8,0.9,1.0,1.2,1.5,2.0,3.0 um Spacing between the lines 10um constant Metal Line Isolation Implant Line

18. Boston University NAIL – Parallel Devices There are two separate Parallel Devices 0.8-1.2 um parallel device 1.5-3.0 um parallel device Each device contains 3 samples, and each sample has lines of variable width and constant spacing in between Metal Line Isolation Implant Line

19. Boston University Nanowire Devices Similar size and dimensions as in NAIL devices Large metal contacts for easy activation Implant areas a varying space apart for nanowire lines to be drawn

20. Boston University Nanowire Devices There are 2 different nanowire devices with 3 samples on each device. Separation distances between the implant areas are: 1, 2, 3, 5, 10, and 20um

21. Boston University Sample Device Fabrication 5 Masks manufactured, 4 being used 4 inch wafer platform 5 p-type lightly doped wafers Implants used all n-type Using BU ECE semiconductor manufacturing lab equipment, ion implanters from Implant Sciences, and potentially other tools.

22. Boston University Fabrication – Silicon Wafers Lightly P-doped Silicon Wafers 5 Pieces One side polished Si 22 ohm*cm Boron (p-) doped wafer

23. Boston University Phase 1 – Photoresist Application PR Shipley S1813 Photoresist 4000 RPM for 30 Seconds Uniform 1.5um thickness Development Photoresist S1813, Thickness=1.5um Si 22 ohm*cm Boron (p-) doped wafer

24. Boston University Phase 1 - Mask 1 Exposure UV Exposure using S. Microtek Expose at 8mW for 12sec Mask 1 Si 22 ohm*cm Boron (p-) doped wafer

25. Boston University Phase 1 - Etching into Silicon Etch 700nm into Silicon Isolation Trench and Aligner Markers Easier Navigation while Processing Si 22 ohm*cm Boron (p-) doped wafer

26. Boston University Phase 1 – PR Removal and Cleaning PR Removal using Acetone, Methanol, and DI Water Particle Removal using RIE Asher Si 22 ohm*cm Boron (p-) doped wafer

27. Boston University Phase 2 – P+_130keV Simulation

28. Boston University Phase 2 - Photoresist Application PR S1813 Photoresist 5000 RPM for 60 Seconds Uniform 1.0um thickness Development Photoresist S1813, Thickness=1.0um Si 22 ohm*cm Boron (p-) doped wafer

29. Boston University Phase 2 - Mask 3 Exposure UV Exposure using S. Microtek Expose at 8mW for 12sec Si 22 ohm*cm Boron (p-) doped wafer Mask 3

30. Boston University Phase 2 - P+_130keV Implant Phosphorus Ion Implant at 130keV with 1e15 ions/cm^2 and 7 degree θ angle done at Implant Sciences P+ Si 22 ohm*cm B- doped wafer

31. Boston University Phase 2 - PR Removal and Cleaning PR Removal using Acetone, Methanol, and DI Water Using HTEA recipe on Fusion Asher Si 22 ohm*cm Boron (p-) doped wafer P+

32. Boston University Phase 2 – Ion Implant Anneal 3 minute anneal at 1050C Longer anneal expands the implanted area and activates it fully This implant will create a pn-junction preventing any leakage between the metal contacts. Si 22 ohm*cm B- doped wafer P+

33. Boston University Phase 3 – As+_30keV Simulation

34. Boston University Phase 3 – Photoresist Application PR S1813 Photoresist 6000 RPM for 90 Seconds Uniform sub-1.0um thickness Development Photoresist S1813, Thickness <1.0um Si 22 ohm*cm Boron (p-) doped wafer P+

35. Boston University Phase 3 - Mask 4 Exposure UV Exposure using S. Microtek Expose at 8mW for 12sec Si 22 ohm*cm Boron (p-) doped wafer Mask 3 Mask 4 P+

36. Boston University Phase 3 - As+_30keV Implant Arsenic Ion Implant at 30keV with 1e15 ions/cm^2 and 7 degree θ angle done at Implant Sciences Si 22 ohm*cm B- doped wafer As+ P+

37. Boston University Phase 3 – PR Removal and Cleaning PR Removal using Acetone, Methanol, and DI Water Using Fusion Asher HTEA recipe Si 22 ohm*cm Boron (p-) doped wafer P+ As+

38. Boston University Phase 3 – Ion Implant Anneal 30 second anneal at 1100C Short anneal time prevents the implanted area from expanding Si 22 ohm*cm Boron (p-) doped wafer P+ As+

39. Boston University Phase 4 – Photoresist Application PR S1813 Photoresist 4000 RPM for 30 Seconds Uniform 1.5um thickness Development Photoresist S1813, Thickness=1.5um Si 22 ohm*cm Boron (p-) doped wafer P+ As+

40. Boston University Phase 4 - Mask 5 Exposure UV Exposure using S. Microtek Expose at 8mW for 12sec Si 22 ohm*cm Boron (p-) doped wafer Mask 3 Mask 5 P+ As+

41. Boston University Phase 4 – Aluminum Sputtering Aluminum deposition via evaporation P+ As+

42. Boston University Phase 4 – Aluminum Liftoff and PR Removal Al Liftoff to remove the extra aluminum PR removal using Acetone, Methanol and DI Water P+ As+

43. Boston University Conclusion To provide samples for NAIL thermal imaging and Nanowire projects NAIL: Provide various 0.8um-5.0um features for imaging in various configurations Nanowire: Provide samples with implanted areas connected to large metal contacts A sufficient amount of samples Leave a foundation for simpler future sample device manufacturing

44. Boston University Questions?