Authors: M. Kimura, M. Hobara
Affilation: Tohoku Gakuin University, Japan
Pages: 642 - 645
Keywords: infrared absorber, film, porous metal, thermal infrared sensor, silicon
Novel fabrication method of porous chromium (Cr) film for an infrared (IR) absorber is proposed, and total absorption factor above 93% at about 10 micron m of the IR wavelength, which is corresponding to the peak wavelength of our body temperature of 37 ºC, considering the transmissivity T of 0.3% for the IR absorber formed at the substrate temperature Ts=400 ºC is achieved. The porous Cr film is formed on the silicon substrate because of MEMS type thermal IR sensor. Our infrared absorber is composed of porous Cr film remained after chemical etching of co-sputtered copper (Cu) with Cr, and the composition rate of Cu and Cr is varied (graded composition film: Cr:Cu =20:80/ Cr:Cu =50:50 / Ti (underlying metal)) according to essential matters considered for the infrared absorber of the thermal IR sensor, especially for our body temperature measurement. We have found that morphology of crystallized Cr in the co-sputtered Cu depends strongly on the underlying metal of Cr and Ti, and also on the substrate temperature Ts, and that as to the Cr film, mesh-like crystals composed of many needle-like crystals are grown.