Thermoelectric-based infrared detector having a cavity and a MEMS structure defined by BEOL metals lines

Device and method of forming a device are disclosed. The device includes a substrate with a transistor component disposed in a transistor region and a micro-electrical mechanical system (MEMS) component disposed on a membrane over a lower sensor cavity in a hybrid region. The MEMS component serves as thermoelectric-based infrared sensor, a thermopile line structure which includes an absorber layer disposed over a portion of oppositely doped first and second line segments. A back-end-of-line (BEOL) dielectric is disposed on the substrate having a plurality of inter layer dielectric (ILD) layers with metal and via levels. The ILD layers include metal lines and via contacts for interconnecting the components of the device. The metal lines in the metal levels are configured to define a BEOL or an upper sensor cavity over the lower sensor cavity, and metal lines of a first metal level of the BEOL dielectric are configured to define a geometry of the MEMS component.