These days, uncooled IR image sensors utilizing MEMS technologies have been widely studied for night vision
and temperature sensing. Compared with other uncooled IR image sensor, uncooled IR image sensor utilizing p-n
junction diode detector has merits of good CMOS compatibility, better mass-production, and better detecting
uniformity. In this paper, we proposed a novel uncooled IR sensor based on lateral polysilicon p-n junction diode.
In the CMOS process, p-type polysilicon is used for PMOS gate electrode material, while n-type polysilicon is
used for NMOS gate electrode material. Due to that polysilicon diode is adopted for sensing, the silicon substrate
under the microstructure can be completely removed, and a better thermal isolation and a small thermal mass
can be achieved. By using the FEM software Ansys, 3D models of the silicon diode and polysilicon diode have
been built for thermal simulation. Simulation results verify that a better thermal isolation can be achieved for
polysilicon diode. The device was fabricated by standard CMOS process and a XeF2 post-CMOS maskless dry
etching step. Measurement results of the fabricated lateral polysilicon p-n junction diode is also reported.