A novel, silicon microfabricated infrared video bolometer

We report on a new type of infrared video bolometer (IRVB) recently developed at the National Institute of Standards and Technology (NIST). Using standard silicon microfabrication processes, we have made a 40 mm x 40 mm prototype IRVB with none of the disadvantages associated with metal foils such as: pin-hole defects, thickness variation, and lateral (in-plane) heat spreading. Instead, a pin-hole free, thin film metal with less than 2% thickness non-uniformity across a 150 mm diameter is lithographically defined into individual pixels thereby minimizing lateral heat spreading. The metal pixels are further thermally decoupled from the silicon substrate by supporting them on a low thermal conductivity silicon nitride membrane. Finally, vertically aligned carbon nanotubes are grown at 800 C on both sides of the IRVB for broadband absorption of radiation as well as near unity emissivity for temperature measurement. We will discuss in detail the advantages of a silicon microfabricated IRVB and present initial measurement data on key performance metrics such as temperature responsivity and thermal time constants of individually measured pixels.