| Pb(Zrx,Ti1-x)O3 thin films have important applications in infrared pyroelectric detector, ferroelectric random access memory, optical modulator and capacitors for their excellent ferroelectric, piezoelectric, electric-optical, pyroelectric and other performances, which provide favorable conditions for the miniaturization and integrated in integrated circuits. There are several methods for depositing ferroelectric thin films, among which metal organic chemical vapor deposition (MOCVD) method is widely used in large-scale production, low temperature, high compatibility with silicon integration process and other advantages. According to restriction of gaseous metal-organic source of MOCVD, the author adopts liquid delivery technology and plasma enhancing on MOCVD device to facilitate a successful deposition of PZT ferroelectric thin films.Conventional gaseous source MOCVD requires similar or identical vapor pressures between different compounds, which restrict the choice of metal-organic source and make it hard to deposit the majority of semiconductor films, superconductor thin films and ferroelectric thin films. Based on the principle of MOCVD, the present thesis uses the liquid delivery technology, ultrasonic atomizing technology, plasma enhanced technology to prepare PZT thin film successfully. Meanwhile, the thesis points out that plasma enhanced liquid source MOCVD mainly consists of liquid delivery system, vacuum system, ultrasonic atomizer, plasma enhanced system, temperature control system, automatic control system, exhaust treatment components and so on. After being prepared with the Zr/Ti ratio of 30/70 and lead in excess of 15%, MO precursor is delivered to ultrasonic atomizer and atomize, then the plasma produced by radio-frequency discharge miniaturize the fogdrop and deposit it on the substrate with a certain temperature.Firstly, the TiO2 thin films were deposited by MOCVD to verity the system. TiO2 thin film is measured by ellipsometer, after fitting it is observed that the refractive index is 2.3, extinction efficient is 0.03 and thickness is 359.0 nm. And it is found that thin film shows (101) orientation measured by X-ray diffractometer (XRD), which is the same as what of standard graph. Then the PZT thin films are deposited as well. Optimum processing parameter is obtained by several experiments:flow of Ar and O2 is 200sccm and 400sccm respectively; liquid flow is 0.025ml/min; deposition pressure is 100-150 Pa; deposition temperature is 500-550℃; atomization power is 9-12 W; RF power is 400 W. Then XRD of PZT thin film is measured after heat treatment at 700℃. The result indicates that the film shows a preferred orientation at (110) diffraction peak, and obvious perovskite structure is formed.The pyroelectric detect array structure is designed and also fabricated.2×9 array single point electrode is adopted, and the area of each electrode is 0.04mm2. Ni/Cr is employed as the electrode material, the electrode of sensing unit is prepared by using lithographic process and lift-off technology, which lays a good foundation for the electrical properties testing and application of infrared pyroelectric detector. |
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