Feature-size reduction of photopolymerized structures by femtosecond optical curing of SU-8

The universal scaling of a width of photopolymerized line on the exposure dose was observed in polymerization by direct laser writing using tightly focused femtosecond pulses in SU-8 resist. This scaling can be explained as the photopolymerization by a blackbody-type emission. A spectrally broad thermal emission of electrons heated up to temperatures approximately Te∼103K coincides with an IR-absorption band of SU-8 centered at the 2.9μm and had caused polymerization by a cumulative direct absorption. Three-dimensional photonic crystal templates with approximately twice reduced feature size were fabricated with stop band at the fiber communication wavelength of 1.3μm.

[1]  Quintin Johnson,et al.  First X-Ray Diffraction Evidence for a Phase Transition during Shock-Wave Compression , 1972 .

[2]  Saulius Juodkazis,et al.  Three‐Dimensional Spiral‐Architecture Photonic Crystals Obtained By Direct Laser Writing , 2005 .

[3]  B J Schwartz,et al.  Single-shot two-photon exposure of commercial photoresist for the production of three-dimensional structures. , 1998, Optics letters.

[4]  Saulius Juodkazis,et al.  Two-photon lithography of nanorods in SU-8 photoresist , 2005 .

[5]  Saulius Juodkazis,et al.  Reduction of capillary force for high-aspect ratio nanofabrication , 2005 .

[6]  Saulius Juodkazis,et al.  Control over the Crystalline State of Sapphire , 2006 .

[7]  M. Wegener,et al.  Direct laser writing of three-dimensional photonic-crystal templates for telecommunications , 2004, Nature materials.

[8]  Saulius Juodkazis,et al.  Recording and reading of three-dimensional optical memory in glasses , 2003 .

[9]  Raymond C Rumpf,et al.  Fully three-dimensional modeling of the fabrication and behavior of photonic crystals formed by holographic lithography. , 2004, Journal of the Optical Society of America. A, Optics, image science, and vision.

[10]  Steven J. Holmes,et al.  Negative photoresists for optical lithography , 1997, IBM J. Res. Dev..

[11]  J. Crivello.  Photoinitiated Cationic Polymerization , 1983 .

[12]  Jane M. Shaw,et al.  Micromachining applications of a high resolution ultrathick photoresist , 1995 .

[13]  M. Wegener,et al.  Direct laser writing and characterization of “Slanted Pore” Photonic Crystals , 2004 .

[14]  J. P. Callan,et al.  Three-dimensional optical storage inside transparent materials. , 1996, Optics letters.

[15]  Xiaocong Yuan,et al.  Photothermally enabled lithography for refractive-index modulation in SU-8 photoresist. , 2006, Optics letters.

[16]  B. Luther-Davies,et al.  Ablation of solids by femtosecond lasers: ablation mechanism and ablation thresholds for metals and dielectrics , 2002 .