Polymer microlens arrays applicable to AlInGaN ultraviolet micro-light-emitting diodes

We report on the fabrication of high-optical-quality microlens arrays based on ultraviolet (UV)-curable polymer adhesive. The lenses are suitable, amongst other applications, for high-transmission and projection of the output of UV micropixellated light-emitting diodes. The microlenses were fabricated using a resist-reflow technique with reactive ion etching. An O/sub 2/--CF/sub 4/ etch-gas chemistry, where atomic fluorine eliminates the carbon-related polymer residue at the etch front effectively, resulted in etch rates of 1.4 /spl mu/m per minute for the polymer. Spherical microlenses of root mean square surface roughness 3 nm were obtained.

[1]  Erdan Gu,et al.  Beam divergence measurements of InGaN / GaN micro-array light-emitting diodes using confocal microscopy , 2005 .

[2]  C. Vallance,et al.  Absolute total electron impact ionization cross-sections for perfluorinated hydrocarbons and small halocarbons , 2001 .

[3]  S. Wolf,et al.  Silicon Processing for the VLSI Era , 1986 .

[4]  Arpad A. Bergh,et al.  Blue laser diode (LD) and light emitting diode (LED) applications , 2004 .

[5]  E. Gu,et al.  High-density matrix-addressable AlInGaN-based 368-nm microarray light-emitting diodes , 2004, IEEE Photonics Technology Letters.

[6]  Hongxing Jiang,et al.  GaN microdisk light emitting diodes , 2000 .

[7]  Yong-Le Pan,et al.  Application of light-emitting diodes for aerosol fluorescence detection. , 2003, Optics letters.

[8]  Larry A. Coldren,et al.  Fabrication of refractive microlenses in semiconductors by mask shape transfer in reactive ion etching , 1997 .

[9]  Michael C. Hutley,et al.  Microlens arrays , 1992, Other Conferences.

[10]  Erdan Gu,et al.  Reflection/transmission confocal microscopy characterization of single-crystal diamond microlens arrays , 2004 .

[11]  M. Dawson,et al.  Mask-free photolithographic exposure using a matrix-addressable micropixellated AlInGaN ultraviolet light-emitting diode , 2005 .

[12]  Grigory Simin,et al.  High-power deep ultraviolet light-emitting diodes basedon a micro-pixel design , 2004 .

[13]  P. Nussbaum,et al.  Design, fabrication and testing of microlens arrays for sensors and microsystems , 1997 .

[14]  S. J. Pearton,et al.  Reduction of sidewall roughness during dry etching of SiO2 , 1992 .

[15]  C. Griffin,et al.  Fluorescence excitation and lifetime measurements using GaN/InGaN micro-LED arrays , 2004, The 17th Annual Meeting of the IEEELasers and Electro-Optics Society, 2004. LEOS 2004..