Structure Simulation And Technology Of BST Ferroelectric Films Phase Shifter

Compared with others, the ferroelectric films based phase shifter has many better advantages, such as low cost, small valume, anti-radiation, small drive power, high reliability and so on, and it has attracted much more attention especially in military radar field in recent years. In this dissertation, we have done some theoretical research and experimental fabrication of interdigital capacitor loading on the CPW, designed CPW-MS transition structure which makes CPW matching with external microstrip circuit, and discussed the improvement of double periodic structure. At last, the unit structure of single periodic and double periodic phase shifter is fabricated successfully using semiconductor technology, introduced testing solution of the phase shifter.The effection to device performence of interdigital capacitor structure parameters including the width and length of interdigital electrode, the width between interdigital electrode is analyzed using HFSS software. According to result analyzed, it is difficult to obtain large phase shift and small loss simultaneously, and the parameters chosen need to compromise according to actual situation.The phase shifter model with CPW-MS transformation structure is simulated by using HFSS software and when the width of microstrip is a fixed value, the larger the angle of CPW-MS, namely the smaller the length of CPW-MS, the smaller the loss, but the phase shift of device can not change significantly unless the length of CPW-MS is large enough. The different distances of adjacent interdigital capacitor of double periodic structure are discussed, and got the optimal length of the L1 and L2 that lead to impedance matching in wider band; moreover as a result, the loss of some single frequency point can be reduced, optimize the performance of device.The final design parameters is derived by relevant conclusions of this paper and experimental group as width of signal line is 40μm to 60μm, the width of slot is 10μm to 20μm without interdigital electrodes, otherwise is 70μm, the length of interdigital electrode is 40μm to 60μm, the width of interdigital electrode is 4μm to 8μm, the width between interdigital electrode is 8μm to 12μm; the substrate can be Sapphire or Si; electrode materials can be Al,Cu and Pt; The thickness of BST thin films is 0.3μm to 0.8μm, the thickness of Al and Cu is over 1.152μm and 0.934μm respectively.The unit structures of single and double periodic phase shifter are fabricated successfully using lift-off technology, the graphics are complete and clear and the fabrication effect is good. At last, on-chip test technology which can be used for analysis of device performence is proposed.