硅基PZT热释电厚膜红外探测器的研制

Preparation of Si-based PZT pyroelectric thick film infrared detector

在(100)单晶Si衬底上,采用MEMS工艺和丝网印刷方法制作了锆钛酸铅(PZT)厚膜热释电红外探测器,深入研究了PZT厚膜材料的制备方法与器件加工工艺。采用四甲基氢氧化铵(TMAH)溶液腐蚀Si衬底制备硅杯结构。为防止Pb和Si相互扩散,在Pt底电极与SiO2/Si衬底之间通过射频反应溅射制备了Al2O3薄膜阻挡层。采用丝网印刷在硅杯中制备了30μm厚的PZT材料,并用冷等静压技术提高厚膜的致密度,实现了PZT厚膜在850℃的低温烧结。PZT厚膜在1 kHz、25℃下的相对介电常数与损耗角正切分别为210和0.017,动态法测得热释电系数为1.5×10-8Ccm-2K-1。最后制备了敏感元为3 mm×3 mm的单元红外探测器,使用由斩波器调制的黑体辐射,在调制频率为112.9 Hz时测得器件的探测率达到最大值7.4×107cmHz1/2W-1。

Lead zirconate titanate（PbZr0.3Ti0.7O3） thick films and single element detectors for pyroelectric applications were fabricated on Si（100） substrates by MEMS and screen-printing technology.The preparation method and device processing technology were studied in detail.Firstly,the silicon-cup was etched by tetra-methyl ammonium hydroxide（TMAH） solution.Secondly,the Al2O3 barrier layer was prepared to prevent Si diffusion between PZT/ Si through reactive radio frequency（RF） sputtering.Cool isostatic pressing experiments were conducted in order to increase the density of PZT thick films.Finally,the PZT ceramic thick films about 30 μm were achieved at a low sintering temperature about 850 ℃.The dielectric permittivity and loss angle tangent tested at 1 kHz under 25 ℃ were 210 and 0.017 respectively.By using dynamic current method,pyroelectric coefficient of the PZT thick film was determined to be 1.5×10-8 Ccm-2K-1.The detectivity of detector with 3 mm×3 mm area was measured by mechanically chopped blackbody radiation as the function of frequency.The results show that the single element detector obtains its maximum detectivity 7.4×107 cmHz1/2W-1 at 112.9 Hz.