Abstract
Laser-assisted direct imprinting (LADI) technique has been proposed to utilize an excimer laser to irradiate and heat up the substrate surface through a highly-transparent quartz mold preloaded on this substrate for micro- to nano-scaled structure fabrications. While the melting depth and molten duration are key issues to achieve a satisfactory imprinting pattern transfer, many material property issues such as crystalline phase alteration, grain size change and induced film stress variation are strongly affected by transient thermal response. With one-dimensional simplification as a model for the LADI technique, the present paper has successfully derived an analytical solution for the arbitrary laser pulse distribution to predict the relevant imprinting parameters during the laser induced melting and solidification processes. The analytical results agree quite well with the experimental data in the literature and hence can be employed to further investigate the effects of LADI technique from laser characteristics (wavelength, fluence and pulse duration) and substrate materials (silicon and copper) on the molten duration, molten depth and temperature distributions. Three kinds of excimer laser sources, ArF (193 nm), KrF (248 nm) and XeCl (308 nm) were investigated in this study. For the silicon substrate, the melting duration and depth were significantly dictated by the wavelength of laser used, indicating that employing the XeCl excimer laser with longer pulse duration (30 ns in the present study) will achieve the longest molten duration and deepest melting depth. As for the copper substrate, the melting duration and depth are mainly affected by the laser pulse duration; however, the wavelength of laser still plays an insignificant role in LADI processing. Meanwhile, the laser fluence should properly be chosen, less than 1.4 J/cm2 herein, so as to avoid the substrate temperature exceeding the softening point of the quartz mold (~1950 K) and to make sure that the mold can still maintain the original features.
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References
Bogaerts A, Chen Z, Gijbels R, Vertes A (2003) Laser ablation for analytical sampling: what can we learn from modeling? Spectrochimica Acta Part B 58:1867–1893
Ameer-Beg S, Perrie W, Rathbone S, Wright J, Weaver W, Champoux H (1998) Femtosecond laser microstructuring of materials. Appl Surface Sci 127–129:875–880
Marcinkevicius A, Juodkazis S, Watanabe M, Miwa M, Matsuo S, Misawa H, Nishii J (2001) Femtosecond laser-assisted three-dimensional microfabrication in silica. Opt Lett 26:277–279
Chrisey DB, Hubler GK (eds) (1994) Pulsed Laser Deposition of Thin Films. Wiley, New York
Becker MF, Brock JR, Cai H, Henneke DE, Keto JW, Lee J, Nichols WT, Glicksman HD (1998) Metal nanoparticles generated by laser ablation. Nanostructured Mater 10(5):853–863
Hertel IV, Stoian R, Ashkenasi D, Rosenfeld A, Campbell EEB (2001) On the physics of material processing with femtosecond lasers. Riken Rev 32:23–30
Rudolph P, Brzezinka K-W, Wasche R, Kautek W (2003) Physical chemistry of the femtosecond and nanosecond laser–material interaction with SiC and a SiC–TiC–TiB2 composite ceramic compound. Appl Surface Sci 208–209:285–291
Xu X, Song KH (2000) Phase change phenomena during high power laser-materials interaction. Mater Sci Eng A 292:162–168
Craciun V, Craciun D, Bunescu MC, Dabu R, Boyd IW (1999) Scanning electron microscopy investigation of laser ablated oxide targets. J Phys D 32:1306–1312
Kitahara K, Suga K, Hara A, Nakajima K (1996) Phase variation of amorphous-Si and poly-Si thin films with excimer laser irradiation. Japanese J of Appl Phys 35:L1473–L1475
Watanabe H, Miki H, Sugai S, Kawasaki K, Kioka T (1994) Crystallization process of polycrystalline silicon by KrF excimer Laser Annealing. Japanese J Appl Phys 33:4491–4498
Ulrych I, Cernik M, El-Kader KMA, Prikryl P, Cerny R, Chvoj Z, Chab V (1996) Time resolved reflectivity studies of phase transitions in polycrystalline Si induced by excimer laser irradiation. Solid State Phenomena 51–52:173–178
Kitahara K, Yamazaki R, Kurosawa T, Nakajima K, Moritani A (2002) Analysis of stress in laser-crystallized polysilicon thin films by Raman scattering spectroscopy. Japanese J Appl Phys 41:5055–5059
Lee CW, Ko MK, Woo SL, Oh HW, Gho SJ, Lee JY (1998) Comparison of the stress between rapid thermal annealed and excimer laser annealed polycrystalline silicon thin films. Solid State Communications 105(12):777–781
Wang J, Weaver RL, Sottos NR (2002) A parametric study of laser induced thin film spallation. Exp Mech 42:74–83
Pecora A, Mariucci L, Carluccio R, Fortunato G, Legagneux P, Plais F, Reita C, Pribat D, Stoemenos J (1998) Combined solid phase crystallization and excimer laser annealing process for polysilicon thin-film transistors. Physica Status Solidi (a) 166:707–714
Chou SY, Krauss PR Renstrom PJ (1996) Imprint lithography with 25-nanometer resolution. Sci 272(5258):85–87
Guo L, Krauss PR, Chou SY (1997) Nanoscale silicon field effect transistors fabricated using imprint lithography. Appl Phys Letters 71(13):1881–1883
Chou SY, Krauss PR (1997) Imprint lithography with sub-10 nm feature size and high throughput. Microelectronic Eng 35(1–4):237–240
Zhang W, Chou SY (2003) Fabrication of 60-nm transistors on 4-in. wafer using nanoimprint at all lithography levels. Appl Phys Letters 83(8):1632–1634
Wu W, Gu J, Ge H, Keimel C, Chou SY (2003) Room-temperature Si single-electron memory fabricated by nanoimprint lithography. Appl Phys Letters 83(11):2268–2270
Chou SY, Keimei C, Gu J (2002) Ultrafast and direct imprint of nanostructures in silicon. Nature 417:835–837
Heavens OS (1965) Optical Properties of Thin Solid Films. Dover Publications, New York
Guenther RD (1990) Modern Optics. John and Wiley & Sons, New York
Tokarev VN, Kaplan AFH (1999) An analytical modeling of time dependent pulsed laser melting. J Appl Phys 86(5):2836–2846
Lide DR (2003) CRC Handbook of chemistry and physics. 84rd ed., CRC Press
Bejan A (1993) Heat Transfer. John Wiley & Sons, Inc., New York
Rubenstein LI (1971) The Stefan problem, Vol. 27. of AMS Translations of Mathematical Monographs. American Mathematical Society, Providence, R.I.
Tsu R, Hodgson RT, Tan TY, Baglin JE (1979) Order-disorder transition in single-crystal silicon induced by pulsed uv laser irradiation. Phys Rev Lett 42(20):1356–1358
Cullis AG, Webber HC, Chew NG, Poate JM, Baeri P (1982) Transitions to defective cystal and the amorphous state induced in elemental Si by laser quenching. Phys Rev Lett 49(3):219–222
Cerny R, Chab V, Prikryl P (1998) Nonequilibrium model of laser-induced phase change processes in amorphous silicon thin films. Phys Rev B 57(1):194–202
Jellison GE, Jr, Lowndes DH, Mashburn DN, Wood RF (1986) Time-resolved reflectivity measurements on silicon and germanium using a pulsed excimer KrF laser heating beam. Phys Rev B 34(4):2407–2415
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Hsiao, F.B., Jen, C.P., Wang, D.B. et al. An analytical modeling of heat transfer for laser-assisted nanoimprinting processes. Comput Mech 37, 173–181 (2006). https://doi.org/10.1007/s00466-005-0688-z
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DOI: https://doi.org/10.1007/s00466-005-0688-z