Surface micromachining and characterization of a pyroelectric infrared ray focal plane array utilizing SiO₂as the IR absorbing layer

Abstract

The development of a surface micromachined infrared ray (IR) focal plane array (FPA), in which a single SiO2 layer functions as an IR absorbing plate and a Pb(Zr0.3Ti0.7)O3 thin film serves as a thermally sensitive material is described. The advantages of using SiO2 as an IR absorbing layer include the fact that it has good IR absorbance within the 8–12 µm spectral range. In this case, about 60% of the incident IR spectrum in this range was absorbed. Another important advantage of SiO2, when applied to the top of the Pt/PZT/Pt stack, is that it functions as a supporting membrane. Consequently, the IR absorbing layer forms as one body on the membrane structure, which simplifies the overall MEMS process and provides a robust structure.

Great enhancement of pyroelectric properties for Ba0.65Sr0.35TiO3 films on Pt–Si substrates by inserting a self-buffered layer

“…The measured detectivity was about 1 ϫ 10 7 cm Hz 1/2 W −1 . 13 Our result of NiCr/ BST/ Pt/ Ti/ SiO 2 is comparable with the abovementioned values. In our work, only 500 nm SiO 2 films underneath the BST film capacitors was adopted serving as thermal isolation layer, whose thermal isolation performance is quite poor than that of micromachined devices due to its relatively high thermal conduction and small film thickness.…”

“…2,4,13 For example, it was reported by Hashimoto et al 4 that the D ‫ء‬ was 2.9 ϫ 10 8 cm Hz 1 W −1 for BST film capacitor on 1 m thick Si membrane, where BST film has a pyroelectric coefficient of 1.8ϫ 10 3 C m −2 K −1 . Rye and Cho developed a 64ϫ 64 array based on Pb͑Zr 0.3 Ti 0.7 ͒O 3 pyroelectric films having 4 ϫ 10 2 C m −2 K −1 pyroelectric coefficient.…”