| 摘要 |
PURPOSE:To increase attenuation at the outside of a band, by providing one thin film layer made of SiO2 and Si3N4 insulating material between a silicon thin film doping a boron with a high concentration and a piezoelectric thin film, and giving a partial electrode at the boundary between this insulating material and the piezoelectric thin film. CONSTITUTION:On the surface of (100) silicon substrate 1, a silicon layer 3 having 1X10<20>/cm<3> boron density is grown by 2mum thickness, and an SiO2 thin film 4 having 3,000Angstrom thickness is formed on the layer 3 by the sputtering method and on the SiO2 thin film, Au is vapor-deposited by 2,000Angstrom thickness by taking Cr as a background to constitute a desired ground electrode pattern 5 with the photolithography, and then a ZnO thin film 6 having 11mum thickness is formed with the sputtering method and an Al electrode 7 is formed on the ZnO thin film with the lift-off. Finally, etching is carried out from the back side of the substrate with an aq. solution of KOH by taking an Si3N4 formed on the silicon as a mask to form the vacant hole of oscillating part. |
