The Preparation Of High Performance Uncooled Pyroelectric Infrared Detectors

Polyvinylidene fluoride(PVDF) and some copolymer based on PVDF have drawn great attention due to their excellent piezoelectric property, ferroelectric characteristics, pyroelectricity, high electrical strength, chemically inert behavior, and durability and so on. Because of that, it can be used for the preparation of large area integrated infrared focal plane array. In this study, the P(VDF-TrFE) ferroelectric thin films were prepared by the method of sol-gel, both the crystallinity and the pyroelectric property were good. Then the relationship between active field and temperature of P(VDF-TrFE) were discussed, after that we focused on the preparation of high performance uncooled pyroelecyric infrared detectors. In order to improve the absorption efficiency of P(VDF-TrFE) ferroelectric thin film devices in infrared band, we introduced surface plasma resonance technology in the production process, and used grating structure as its excitation mode. And then we explored the production processes of infrared focal plane preliminary, which contains the preparation of indium bumps and the choice of transition layer metal in flip chip bonded process. The main results are listed as the following:(1) Through analyzing the pyroelectric property of P(VDF-TrFE) ferroelectric thin films, we acquired that pyroelectric coefficient went up as temperature rising. The value was between20.8and33.1μC/m2K, which indicated that the P(VDF-TrFE)’s pyroelectric property is good. The temperature dependence of activation field may reflect the evolution of the molecule conformation, which can provide useful information to design and optimize the structure of the devices based on P(VDF-TrFE)(2) Through the experiment, we got the parameters about how to make the small sizes grating structure, and manufactured a series of grating structure devices successfully whose periods were6μm,8μm,10μm,16μm,24μm and32μm. The absorption rate of all the grating structure devices is all bigger than the one which has the same area but without the grating structure, which means the grating structure is good for the increasing of the infrared absorption.(3) We prepared the indium bumps through thermal evaporation technology, the height of the bump is more than5μm and the diameter is20μm, they are all suited to the fild-chip. In order to enhance adhesion reliability between indium columns and metal electrodes and prevented interdiffusion, we added the Ti/Pt/Au multilayer metal films(UBM), which did a good job. All of the work laid the foundation for the production of infrared focal plane and made some innovative and meaningful results.