Physics:Thermal scanning probe lithography

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File:Thermal polymer decomp.tiff Thermal scanning probe lithography (t-SPL) is a form of scanning probe lithography[1] (SPL) whereby material is structured on the nanoscale using scanning probes, primarily through the application of thermal energy.

Related fields are thermo-mechanical SPL (see also Millipede memory), thermochemical SPL[2][3] (or thermochemical nanolithography) where the goal is to influence the local chemistry, and thermal dip-pen lithography[4] as an additive technique.

History

Scientists around Daniel Rugar and John Mamin at the IBM research laboratories in Almaden have been the pioneers in using heated AFM (atomic force microscope) probes for the modification of surfaces. In 1992, they used microsecond laser pulses to heat AFM tips to write indents as small as 150 nm into the polymer PMMA at rates of 100 kHz.[5] In the following years, they developed cantilevers with resonance frequencies above 4 MHz and integrated resistive heaters and piezoresistive sensors for writing and reading of data.[6][7] This thermo-mechanical data storage concept formed the basis of the Millipede project which was initialized by Peter Vettiger and Gerd Binnig at the IBM Research laboratories Zurich in 1995. It was an example of a memory storage device with a large array of parallel probes, which was however never commercialized due to growing competition from non-volatile memory such as flash memory. The storage medium of the Millipede memory consisted of polymers with shape memory functionality, like e.g. cross-linked polystyrene,[8] in order to allow to write data indents by plastic deformation and erasing of the data again by heating. However, evaporation instead of plastic deformation was necessary for nanolithography applications to be able to create any pattern in the resist. Such local evaporation of resist induced by a heated tip could be achieved for several materials like pentaerythritol tetranitrate,[9] cross-linked polycarbonates,[10] and Diels-Alder polymers.[11] Significant progress in the choice of resist material was made in 2010 at IBM Research in Zurich, leading to high resolution and precise 3D-relief patterning[12] with the use of the self-amplified depolymerization polymer polyphthalaldehyde (PPA)[12][13] and molecular glasses[14] as resist, where the polymer decomposes into volatile monomers upon heating with the tip without the application of mechanical force and without pile-up or residues of the resist.

Working principle

The thermal cantilevers are fabricated from silicon wafers using bulk – and surface micro-machining processes. Probes have a radius of curvatures below 5 nm, enabling sub-10 nm resolution in the resist.[15] The resistive heating is carried out by integrated micro-heaters in the cantilever legs which are created by different levels of doping. The time constant of the heaters lies between 5 μs to 100 μs.[16][17] Electromigration limits the longterm sustainable heater temperature to 700–800 °C.[17] The integrated heaters enable in-situ metrology of the written patterns, allowing feedback control,[18] field stitching without the use of alignment markers[19] and using pre-patterned structures as reference for sub-5 nm overlay.[20] Pattern transfer for semiconductor device fabrication including reactive ion etching and metal lift-off has been demonstrated with sub-20 nm resolution.[21]

Comparison to other lithographic techniques

Due to the ablative nature of the patterning process, no development step (as in: selective removal of either the exposed or non-exposed regions of the resist as for e-beam and optical lithography) is needed, neither are optical proximity corrections. Maximum linear writing speeds of up to 20 mm/s have been shown[22] with throughputs in the 104 – 105 μm2 h−1 range[1] which is comparable to single-column, Gaussian-shaped e-beam using HSQ as resist.[23] The resolution of t-SPL is determined by the probe tip shape and not limited by the diffraction limit or by the focal spot size of beam approaches, however, tip-sample interactions during the in-situ metrology process create tip wear,[24] limiting the lifetime of the probes. In order to extend the lifetime of the probe tips, Ultrananocrystalline diamond (UNCD)[25] and Silicon-Carbide (SiC)-coated[24] tips or wear-less floating contact imaging methods[26] have been demonstrated. No electron damage or charging is caused to the patterned surfaces due to the absence of electron or ion beams.[21]

References

  1. 1.0 1.1 Garcia, Ricardo; Knoll, Armin W.; Riedo, Elisa (August 2014). "Advanced scanning probe lithography". Nature Nanotechnology 9 (8): 577–587. doi:10.1038/nnano.2014.157. ISSN 1748-3387. PMID 25091447. Bibcode2014NatNa...9..577G. 
  2. Szoszkiewicz, Robert; Okada, Takashi; Jones, Simon C.; Li, Tai-De; King, William P.; Marder, Seth R.; Riedo, Elisa (2007-04-01). "High-Speed, Sub-15 nm Feature Size Thermochemical Nanolithography". Nano Letters 7 (4): 1064–1069. doi:10.1021/nl070300f. ISSN 1530-6984. PMID 17385937. Bibcode2007NanoL...7.1064S. 
  3. Fenwick, Oliver; Bozec, Laurent; Credgington, Dan; Hammiche, Azzedine; Lazzerini, Giovanni Mattia; Silberberg, Yaron R.; Cacialli, Franco (October 2009). "Thermochemical nanopatterning of organic semiconductors". Nature Nanotechnology 4 (10): 664–668. doi:10.1038/nnano.2009.254. ISSN 1748-3387. PMID 19809458. Bibcode2009NatNa...4..664F. 
  4. Nelson, B. A.; King, W. P.; Laracuente, A. R.; Sheehan, P. E.; Whitman, L. J. (2006-01-16). "Direct deposition of continuous metal nanostructures by thermal dip-pen nanolithography". Applied Physics Letters 88 (3): 033104. doi:10.1063/1.2164394. ISSN 0003-6951. Bibcode2006ApPhL..88c3104N. 
  5. Mamin, H. J.; Rugar, D. (1992-08-24). "Thermomechanical writing with an atomic force microscope tip". Applied Physics Letters 61 (8): 1003–1005. doi:10.1063/1.108460. ISSN 0003-6951. Bibcode1992ApPhL..61.1003M. 
  6. Mamin, H.J.; Ried, R.P.; Terris, B.D.; Rugar, D. (June 1999). "High-density data storage based on the atomic force microscope". Proceedings of the IEEE 87 (6): 1014–1027. doi:10.1109/5.763314. ISSN 0018-9219. 
  7. Chui, B. W.; Stowe, T. D.; Kenny, T. W.; Mamin, H. J.; Terris, B. D.; Rugar, D. (1996-10-28). "Low‐stiffness silicon cantilevers for thermal writing and piezoresistive readback with the atomic force microscope". Applied Physics Letters 69 (18): 2767–2769. doi:10.1063/1.117669. ISSN 0003-6951. Bibcode1996ApPhL..69.2767C. 
  8. T. Altebaeumer, B. Gotsmann , H. Pozidis , A. Knoll and U. Duerig, T.; Gotsmann, B.; Pozidis, H.; Knoll, A.; Duerig, U. (2008). "Nanoscale Shape-Memory Function in Highly Cross-Linked Polymers". Nano Letters 8 (12): 4398–403. doi:10.1021/nl8022737. PMID 19367970. Bibcode2008NanoL...8.4398A. 
  9. King, William P.; Saxena, Shubham; Nelson, Brent A.; Weeks, Brandon L.; Pitchimani, Rajasekar (September 1, 2006). "Nanoscale Thermal Analysis of an Energetic Material". Nano Letters 6 (9): 2145–2149. doi:10.1021/nl061196p. ISSN 1530-6984. PMID 16968041. Bibcode2006NanoL...6.2145K. 
  10. Saxena, Shubham (2007). "Nanoscale thermal lithography by local polymer decomposition using a heated atomic force microscope cantilever tip". Journal of Micro/Nanolithography, MEMS, and MOEMS 6 (2): 023012. doi:10.1117/1.2743374. 
  11. Gotsmann, B.; Duerig, U.; Frommer, J.; Hawker, C. J. (2006). "Exploiting Chemical Switching in a Diels–Alder Polymer for Nanoscale Probe Lithography and Data Storage". Advanced Functional Materials 16 (11): 1499. doi:10.1002/adfm.200500724. 
  12. 12.0 12.1 Knoll, Armin W.; Pires, David; Coulembier, Olivier; Dubois, Philippe; Hedrick, James L.; Frommer, Jane; Duerig, Urs (2010). "Probe-Based 3-D Nanolithography Using Self-Amplified Depolymerization Polymers". Advanced Materials 22 (31): 3361–5. doi:10.1002/adma.200904386. PMID 20419710. 
  13. Coulembier, Olivier; Knoll, Armin; Pires, David; Gotsmann, Bernd; Duerig, Urs; Frommer, Jane; Miller, Robert D.; Dubois, Philippe et al. (January 12, 2010). "Probe-Based Nanolithography: Self-Amplified Depolymerization Media for Dry Lithography". Macromolecules 43 (1): 572–574. doi:10.1021/ma9019152. ISSN 0024-9297. Bibcode2010MaMol..43..572C. 
  14. Pires, David; Hedrick, James L.; Silva, Anuja De; Frommer, Jane; Gotsmann, Bernd; Wolf, Heiko; Despont, Michel; Duerig, Urs et al. (2010). "Nanoscale Three-Dimensional Patterning of Molecular Resists by Scanning Probes". Science 328 (5979): 732–735. doi:10.1126/science.1187851. ISSN 0036-8075. PMID 20413457. Bibcode2010Sci...328..732P. 
  15. Cheong, Lin Lee; Paul, Philip; Holzner, Felix; Despont, Michel; Coady, Daniel J.; Hedrick, James L.; Allen, Robert; Knoll, Armin W. et al. (September 11, 2013). "Thermal Probe Maskless Lithography for 27.5 nm Half-Pitch Si Technology". Nano Letters 13 (9): 4485–4491. doi:10.1021/nl4024066. ISSN 1530-6984. PMID 23965001. Bibcode2013NanoL..13.4485C. 
  16. King, William P.; Bhatia, Bikramjit; Felts, Jonathan R.; Kim, Hoe Joon; Kwon, Beomjin; Lee, Byeonghee; Somnath, Suhas; Rosenberger, Matthew (2013). "Heated Atomic Force Microscope Cantilevers and Their Applications". Annual Review of Heat Transfer 16: 287–326. doi:10.1615/AnnualRevHeatTransfer.v16.100. 
  17. 17.0 17.1 Mamin, H. J. (1996-07-15). "Thermal writing using a heated atomic force microscope tip". Applied Physics Letters 69 (3): 433–435. doi:10.1063/1.118085. ISSN 0003-6951. Bibcode1996ApPhL..69..433M. 
  18. "European Patent Register: Scanning probe nanolithography system and method". https://register.epo.org/application?number=EP13184651&tab=main. 
  19. Paul, Ph; Knoll, A. W.; Holzner, F.; Duerig, U. (2012-09-28). "Field stitching in thermal probe lithography by means of surface roughness correlation". Nanotechnology 23 (38): 385307. doi:10.1088/0957-4484/23/38/385307. ISSN 0957-4484. PMID 22948486. Bibcode2012Nanot..23L5307P. 
  20. Rawlings, C.; Duerig, U.; Hedrick, J.; Coady, D.; Knoll, A. (July 2014). "Nanometer control of the markerless overlay process using thermal scanning probe lithography". 2014 IEEE/ASME International Conference on Advanced Intelligent Mechatronics. pp. 1670–1675. doi:10.1109/AIM.2014.6878324. ISBN 978-1-4799-5736-1. 
  21. 21.0 21.1 Wolf, Heiko; Rawlings, Colin; Mensch, Philipp; Hedrick, James L.; Coady, Daniel J.; Duerig, Urs; Knoll, Armin W. (2015-03-01). "Sub-20 nm silicon patterning and metal lift-off using thermal scanning probe lithography". Journal of Vacuum Science & Technology B 33 (2): 02B102. doi:10.1116/1.4901413. ISSN 2166-2746. 
  22. Paul, Philip; Knoll, Armin W; Holzner, Felix; Despont, Michel; Duerig, Urs (2011). "Rapid turnaround scanning probe nanolithography". Nanotechnology 22 (27): 275306. doi:10.1088/0957-4484/22/27/275306. PMID 21602616. Bibcode2011Nanot..22A5306P. 
  23. Grigorescu, A.E.; Van Der Krogt, M.C.; Hagen, C.W.; Kruit, P. (2007). "10nm lines and spaces written in HSQ, using electron beam lithography". Microelectronic Engineering 84 (5–8): 822–824. doi:10.1016/j.mee.2007.01.022. 
  24. 24.0 24.1 Lantz, Mark A.; Gotsmann, Bernd; Jaroenapibal, Papot; Jacobs, Tevis D. B.; O'Connor, Sean D.; Sridharan, Kumar; Carpick, Robert W. (2012). "Wear-Resistant Nanoscale Silicon Carbide Tips for Scanning Probe Applications". Advanced Functional Materials 22 (8): 1639. doi:10.1002/adfm.201102383. 
  25. Fletcher, Patrick C.; Felts, Jonathan R.; Dai, Zhenting; Jacobs, Tevis D.; Zeng, Hongjun; Lee, Woo; Sheehan, Paul E.; Carlisle, John A. et al. (2010). "Wear-Resistant Diamond Nanoprobe Tips with Integrated Silicon Heater for Tip-Based Nanomanufacturing". ACS Nano 4 (6): 3338–44. doi:10.1021/nn100203d. PMID 20481445. 
  26. Knoll, A; Rothuizen, H; Gotsmann, B; Duerig, U (7 May 2010). "Wear-less floating contact imaging of polymer surfaces". Nanotechnology 21 (18): 185701. doi:10.1088/0957-4484/21/18/185701. PMID 20378942. Bibcode2010Nanot..21r5701K. 

See also