Bulk acoustic wave resonator, preparation method, filter and preparation method

Abstract

The invention discloses a bulk acoustic wave resonator, a preparation method, a filter and a preparation method. The preparation method of the bulk acoustic wave resonator comprises the steps that a substrate is provided, and the surface or the interior of the substrate is provided with an acoustic reflection structure; sequentially forming a lower electrode and a piezoelectric layer on the substrate; a mask layer is formed on the surface, away from the lower electrode, of the piezoelectric layer, the mask layer is provided with a microstructure window, and the microstructure window comprises a protruding structure window; a convex structure film layer is formed, the convex structure film layer is located on the surface of the mask layer and in the convex structure window on the piezoelectric layer, and the part, located in the convex structure window on the piezoelectric layer, of the convex structure film layer is of a convex structure; removing the mask layer and the convex structure film layer on the surface of the mask layer; and forming an upper electrode, wherein the upper electrode covers the convex structure and the piezoelectric layer. According to the technical scheme provided by the embodiment of the invention, the preparation process of the bulk acoustic wave resonator is simplified, and the manufacturing cost is reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a bulk acoustic wave resonator, a preparation method, a filter, and a preparation method. Background technique [0002] In recent years, with the development of communication technology, BAW resonators have played an important role in the field of wireless communication due to their small size, high operating frequency, low power consumption, high quality factor, and compatibility with CMOS technology. [0003] Among them, the sandwich structure composed of the lower electrode, the piezoelectric layer and the upper electrode is used as the resonance unit of the bulk acoustic wave resonator. In order to improve the quality factor of the bulk acoustic wave resonator, in the prior art, microstructures such as protruding structures and concave structures are usually arranged under the upper electrode to avoid the loss of acoustic wave energy. The whole film layer of the struc...

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Problems solved by technology

In order to improve the quality factor of the bulk acoustic wave resonator, microstructures such as convex structures and concave structures are usually arranged under the upper electrode in the prior art to avoid the loss of acoustic wave energy, but in the prior art, the protrusions need to be formed first The entire film layer of the structure, and then perform the first photolithography and etching on the entire film layer to obtain the raised structure; then form the recessed structure, and in the process of forming the recessed structure, it is necessary to carry out the second photolithography on the film layer where the recessed structure is located. In the photolithography and etching process, since one side of the concave structure in the microstructure needs to be aligned with one side of the raised structure, there are strict requirements on the position of the first and second photolithography and etching, but in the It is easy to deviate during the alignment process between the position of the second photolithography and etching process and the position of the first photolithography and etching process, so that the relative position between the recessed structure and the raised structure and the preset The relative position does not match, which leads to low yield of bulk acoustic wave resonator

In addition, the multiple etching process also makes the preparation process of the existing bulk acoustic wave resonator too cumbersome

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