A Novel Three-Dimensional Microheater

This letter, for the first time, reports a novel 3-D microheater. A platinum (Pt) heating resistor fabricated by a photoresist-spray-coating-based lift-off process is embedded in a concave dielectric membrane. For thermal isolation, this concave membrane is connected to a bulk silicon chip via two slender beams with a silicon pit formed by anisotropic etching under it. A large active area of 46 960
$\mu \hbox{m}^{2}$
can be heated to 400
$^{\circ}\hbox{C}$
at a power of 30 mW. A low power per active area of
$\hbox{6.39} \times \hbox{10}^{-4}$
has been achieved, which is only half of or less than that in current 2-D microheaters.