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最近已经证明,在硅片的一个界限明确的小区域内,可以刻蚀出高度均匀的薄层并镀上氧化锌优质压电膜和电极,从而构成高频能陷谐振器。最近的分析工作仅适合于纯厚度振动情况。木文分析了硅复合结构中压电薄膜的主要厚度伸缩能陷模。分析结果表明,在晶片上波数不大的范围内,即使硅在晶片平面上呈显著的各向异性,这个平面的色散方程也是各向同性的。从得到的色散关系,可以求出渐近微分方程和相应的边界条件。这个方程描述了振动在厚度伸缩谐振附近的复合晶片表面的模式形状。由于该模是主要厚度伸缩型的,所以就复合平片的基模来说,在电极区通常不产生能陷。然而,如果适当增加电极区外的硅厚度,就能实现电极区内的基模能陷。此外,对硅片上镀氧化锌的情况来说,只要简单地使氧化锌膜比刻蚀掉的硅厚到一定程度,就能在电极区内产生平片基模的能陷。本文将上述渐近微分方程及边界条件应用于矩形电极能陷谐振器稳态振动的分析,并获得了在谐振附近有效的导纳集总参数表示图。本分析适用于各种厚度伸缩模及其伴生的横向泛音。
It has recently been demonstrated that a highly uniform thin film can be etched and coated with a zinc-oxide-based piezoelectric film and electrode in a well-defined small area of the wafer to form a high-frequency trap. Recent analysis is only suitable for pure thickness vibration. The paper analyzes the main thickness of the piezoelectric thin film in silicon composite structure retractable energy trap. The analysis results show that the dispersion equation of this plane is isotropic even in the case of significant anisotropy of silicon in the wafer plane over a small wavenumber range. From the obtained dispersion relations, asymptotic differential equations and the corresponding boundary conditions can be obtained. This equation describes the mode shape of the surface of the composite wafer vibrating near the thickness stretching resonance. As the mold is the main thickness of the telescopic type, so the complex mode of the flat film, the electrode area is usually not able to trap. However, if the silicon thickness outside the electrode region is properly increased, the fundamental mode in the electrode region can be trapped. In addition, in the case of zinc oxide on a silicon wafer, simply by making the zinc oxide film thicker than the etched silicon, energy sinking in the flat base mode can be generated in the electrode region. In this paper, the above asymptotic differential equations and the boundary conditions are applied to the analysis of the steady state vibration of rectangular electrode trap, and the effective admittance lumped parameter representation near the resonance is obtained. This analysis is applicable to various thickness telescopic modes and their associated lateral overtone.