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CN-121690106-B - Acoustic filter and method for manufacturing the same

CN121690106BCN 121690106 BCN121690106 BCN 121690106BCN-121690106-B

Abstract

The invention relates to the technical field of wireless communication, and provides an acoustic filter and a preparation method thereof, wherein the preparation method comprises the following steps of S1, providing a substrate, forming an acoustic layer on the surface of the substrate, and forming an effective acoustic structure by utilizing the acoustic layer; the method comprises the steps of firstly, forming a separation layer on one side, far away from a substrate, of an effective acoustic structure, enabling the separation layer to completely cover the acoustic structure, etching an electric connection window penetrating through the separation layer, and secondly, forming a connection layer on one side, far away from the effective acoustic structure, of the separation layer, enabling the connection layer to completely cover the separation layer, enabling the connection layer to penetrate through the electric connection window and then be connected with the annular grounding end of the acoustic layer, and obtaining the acoustic filter, wherein the thickness of the connection layer is identical with that of the acoustic layer. The acoustic filter has low manufacturing cost and is miniaturized as a whole.

Inventors

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Assignees

  • 深圳飞骧科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260212

Claims (10)

  1. 1. A method of manufacturing an acoustic filter, the method comprising the steps of: S1, providing a substrate, forming an acoustic layer on the surface of the substrate, and forming an effective acoustic structure by utilizing the acoustic layer, wherein the effective acoustic structure comprises an acoustic resonance structure, an input end part, an output end part and an annular grounding end, the input end part and the output end part are respectively connected to opposite ends of the acoustic resonance structure, and the annular grounding end is arranged around the acoustic resonance structure; s2, forming a separation layer on one side of the effective acoustic structure, which is far away from the substrate, so that the separation layer completely covers the effective acoustic structure, and etching an electric connection window penetrating through the separation layer, wherein the thickness of the separation layer is 5-25 nm; S3, forming a connecting layer on one side of the separation layer far away from the effective acoustic structure, enabling the connecting layer to completely cover the separation layer, enabling the connecting layer to pass through the electric connection window and then be connected with the annular grounding end of the acoustic layer, and obtaining the acoustic filter, wherein the thickness of the connecting layer is the same as that of the acoustic layer.
  2. 2. The method of manufacturing an acoustic filter according to claim 1, wherein in the step S1, the acoustic layer is made of aluminum or copper-aluminum alloy material.
  3. 3. The method of claim 1, wherein the active acoustic structure is formed by metal deposition and patterning.
  4. 4. The method according to claim 1, wherein in the step S2, the etching process of the electrical connection window is performed by dry etching or wet etching.
  5. 5. The method of manufacturing an acoustic filter according to claim 1, wherein the thickness of the separation layer is 20nm.
  6. 6. The method of manufacturing an acoustic filter according to claim 1, wherein in the step S2, the separation layer is manufactured by chemical vapor deposition or physical vapor deposition process.
  7. 7. The method of manufacturing an acoustic filter according to claim 1, wherein in the step S3, the connection layer and the annular ground terminal are connected by direct contact with each other through a metal.
  8. 8. The method of manufacturing an acoustic filter of claim 1, wherein the patterned structure of the connection layer corresponds to a position of the electrical connection window.
  9. 9. The method of manufacturing an acoustic filter according to claim 1, wherein the substrate is made of a piezoelectric material.
  10. 10. An acoustic filter produced by the method of producing an acoustic filter according to any one of claims 1 to 9.

Description

Acoustic filter and method for manufacturing the same Technical Field The invention relates to the technical field of wireless communication, in particular to an acoustic filter and a preparation method thereof. Background With the explosive growth of the full-scale commercial and internet of things equipment of the fifth generation mobile communication technology, the modern wireless communication system is rapidly evolving towards high frequency, integration and multi-modeling. As a key frequency control element in the radio frequency front end module, the surface acoustic wave filter plays an irreplaceable role in signal selection, interference suppression, and the like. However, the physical size of the conventional Surface Acoustic wave filter (Surface Acoustic wave filter WAVE FILTER, SAW) has become one of the main bottlenecks that restrict the further miniaturization and high performance of the entire rf module. This challenge stems primarily from two fundamental driving forces, first, the hard constraint of "limited space". In order to support a plurality of frequency bands (such as n77, n78 and n79 frequency bands of 5G Sub-6 GHz), tens of or hundreds of filters must be integrated on a single main board to form a complex filter bank. The size of conventional saw filters has made it difficult to meet the demands for high density integration, forcing the industry to move to smaller package solutions. Second, is an inherent requirement of "system performance". The filter size is directly related to the acoustic wavelength of its resonator, and a decrease in size may lead to a decrease in Quality Factor (Q value), an increase in insertion loss, and a narrowing of bandwidth, which is contrary to the requirements of the system for high selectivity and low loss. In the related art, in order to realize a core technology path with a reduced size, a long-term focus is on improving the operating frequency and the energy-binding capability of the device. Conventional approaches include using higher acoustic velocity piezoelectric substrate materials (e.g., higher order cuts of lithium tantalate, lithium niobate) or shrinking electrode linewidths of interdigital transducers. However, these approaches all suffer from significant bottlenecks, namely, the high acoustic speed material tends to be accompanied by the reduction of the electromechanical coupling coefficient, so that the bandwidth is limited, and after the line width of the electrode enters submicron level, the limit of the traditional photoetching process is faced, the electrode resistance is caused to be increased sharply, so that the insertion loss is deteriorated, and the power tolerance is reduced. In addition, conventional SAW energy concentrates on the surface, limiting its performance in higher frequency bands, and it is also difficult to achieve high performance resonance in smaller areas. Accordingly, the industry continues to explore breakthrough technology such as very high longitudinal wave surface acoustic wave (Incredible High Performance Surface Acoustic Wave, IHP-SAW) and transverse bulk wave resonator (LATERALLY EXCITED BULK ACOUSTIC RESONATOR, XBAR) based thin film substrates, which achieves superior performance at higher frequencies by exciting and confining acoustic energy in a multilayer thin film. The development of the technologies marks that the miniaturization of the surface acoustic wave filter is scaled from a simple geometric dimension and enters a deep innovation stage based on the collaborative design of a new material system, a new acoustic mode and a three-dimensional micro-nano structure. Under the background, how to comprehensively optimize core performance indexes such as insertion loss, bandwidth, out-of-band rejection, power capacity and the like of a filter while breaking through the size limit becomes the focus of research and development and patent layout of the current technology. However, under the limited chip area, in order to realize the wiring and interconnection of the multilayer metal, the conventional surface acoustic wave filter often uses a bypass structure, and the structure can lead to the increase of the layout size of the surface acoustic wave device requiring the multilayer metal wiring, so that the material cost is increased intangibly, and meanwhile, the effective chip area of the acoustic device is occupied, and the improvement of the filter performance is affected. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a preparation method of an acoustic filter, which aims to solve the problems of high manufacturing cost, large whole occupied area and poor performance of the existing acoustic filter. In order to solve the technical problems, the invention adopts the following technical scheme: in a first aspect, an embodiment of the present invention provides a method for preparing an acoustic filter, including the steps of: S1, providing a substrate, forming a