A CMOS-MEMS Thermopile With Low Thermal Conductance and a Near-Perfect Emissivity in the 8–14-$\mu\hbox{m}$ Wavelength Range

A CMOS-MEMS polysilicon/metal thermopile with low thermal conductance and a high emissivity in 8-14 μm is presented in this letter. Instead of a traditional aluminum layer with a high thermal conductivity, a titanium film was compatibly introduced to the CMOS process to highly decrease the solid conductance and enhance the responsivity of the infrared sensor. In addition, the solid conductance was further reduced by adopting the design of line-shaped etching windows to isolate heat flow. Furthermore, a gold-black film was evaporated and patterned in situ as the absorber of the sensor to achieve an almost total absorption of received infrared. The responsivity of the poly/Ti thermopile may be about 6.9 times greater than that of the fully standard CMOS poly/Al thermopile without the line-shaped windows and the gold-black coating.