Uncooled Microbolometer Arrays With High Responsivity Using Meshed Leg Structure

In this letter, a meshed leg structure is proposed for the first time to control the thermal conductivity in the uncooled microbolometer arrays without changing the fill factor. An amorphous silicon-based microbolometer was fabricated with 64 × 64 arrays with a 35 μm pixel pitch to verify the proposed design. The hole in the meshed leg was 0.7 × 0.7 μm². The uniformity of the pixel resistance within the 64 × 64 arrays was below 2%. Self-heating and responsivity under infrared (IR) irradiation were investigated in three leg types: 1) type 1-normal leg structure; 2) type 2-meshed leg structure; and 3) type 3-metal extended leg structure. Comparison of the IR irradiation current showed the responsivity of the proposed structure (type 2) that was improved by four times over type 3. For the thermal noise equivalent temperature difference value, type 2 is 194 mK, which is much better than 384 mK of type 3.