Film layer structure of temperature-compensated surface acoustic wave filter

Abstract

The utility model discloses a film layer structure of a temperature compensation surface acoustic wave filter, the film layer structure comprises a piezoelectric substrate layer, a temperature compensation layer and a plurality of resonators arranged on the piezoelectric substrate layer, all the resonators comprise a plurality of series resonators and a plurality of parallel resonators, each resonator comprises a plurality of metal finger strips, and the metal finger strips are arranged on the piezoelectric substrate layer. The temperature compensation layer is arranged on the upper surfaces of the resonators and covers the upper surface of the whole piezoelectric substrate layer, and the bandwidth adjusting layer is arranged on the upper surface of the temperature compensation layer corresponding to the metal finger strips of all the series resonators or the parallel resonators, so that the purpose of increasing or reducing the bandwidth of the temperature compensation surface acoustic wave filter is achieved. The film layer structure can effectively increase or reduce the bandwidth of the temperature-compensated surface acoustic wave filter, so that the temperature-compensated surface acoustic wave filter product meets the index requirements of a user, the user requirements are met, and product scrapping or re-tape-out is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of surface acoustic wave, relates to a temperature-compensated surface acoustic wave filter, and particularly relates to a membrane layer structure of the temperature-compensated surface acoustic wave filter. Background Art

[0002] The surface acoustic wave filter is composed of several resonators connected in series and in parallel, and is divided into ordinary surface acoustic wave filters, temperature-compensated surface acoustic wave filters, and high-performance surface acoustic wave filters. The so-called temperature-compensated surface acoustic wave filter reduces the impact of temperature changes on the filter performance through a built-in temperature compensation layer, thereby achieving stable frequency characteristics under different ambient temperatures, and is widely used in the field of communications.

[0003] In the prior art, the temperature compensation layer of a temperature-compensated surface acoustic wave filter is usually a silicon dioxide layer. However, during the testing of the filter products, it was found that the bandwidth that affects the key indicators of the device often exceeds the product specification range, sometimes higher than the user's usage range indicator, and sometimes lower than the user's usage range indicator, thereby failing to meet user needs, resulting in product scrapping, or re-adjusting the process parameters according to the designer's design simulation before tape-out. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a membrane structure of a temperature-compensated surface acoustic wave filter, which can effectively increase or decrease the bandwidth of the temperature-compensated surface acoustic wave filter, so that the temperature-compensated surface acoustic wave filter product meets user index requirements and satisfies user needs, avoiding product scrapping or re-spinning.

[0005] The technical solution of the utility model is achieved in this way:

[0006] A membrane structure of a temperature-compensated surface acoustic wave filter comprises a piezoelectric substrate layer, a temperature compensation layer and a plurality of resonators arranged on the piezoelectric substrate layer, wherein all resonators are composed of a plurality of series resonators and a plurality of parallel resonators, each resonator comprises a plurality of metal fingers, the temperature compensation layer is arranged on the upper surface of the resonator and covers the upper surface of the entire piezoelectric substrate layer, and a bandwidth adjustment layer is arranged on the upper surface of the temperature compensation layer corresponding to the metal fingers of all series resonators or parallel resonators, thereby achieving the purpose of increasing or decreasing the bandwidth of the temperature-compensated surface acoustic wave filter.

[0007] Furthermore, the bandwidth adjustment layer is a silicon nitride layer.

[0008] Furthermore, the bandwidth adjustment layer has a thickness of 5-80 nm.

[0009] Furthermore, the temperature compensation layer is a silicon dioxide layer with a thickness of 25-80 nm.

[0010] Compared with the prior art, the utility model has the following beneficial effects:

[0011] The utility model arranges a silicon nitride layer on the upper surface of the temperature compensation layer corresponding to the metal fingers of all series resonators or parallel resonators of the temperature compensated surface acoustic wave filter, thereby achieving the purpose of increasing or decreasing the bandwidth of the temperature compensated surface acoustic wave filter and avoiding the scrapping or re-spinning of the temperature compensated surface acoustic wave filter product. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 -Structural schematic diagram of the utility model.

[0013] Among them: 1-piezoelectric substrate layer; 2-metal fingers; 3-temperature compensation layer; 4-bandwidth adjustment layer. DETAILED DESCRIPTION

[0014] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0015] See also Figure 1 A membrane structure of a temperature-compensated surface acoustic wave filter, comprising a piezoelectric substrate layer 1, a temperature compensation layer 3 and a plurality of resonators arranged on the piezoelectric substrate layer 1, all resonators comprising a plurality of series resonators and a plurality of parallel resonators, each resonator comprising a plurality of metal fingers 2, the temperature compensation layer 3 being arranged on the upper surface of the resonator and covering the entire upper surface of the piezoelectric substrate layer 1, and a bandwidth adjustment layer 4 being arranged on the upper surface of the temperature compensation layer corresponding to the metal fingers of all series resonators or parallel resonators, thereby achieving the purpose of increasing or decreasing the bandwidth of the temperature-compensated surface acoustic wave filter. The bandwidth adjustment layer is a silicon nitride layer with a thickness of 5 to 80 nm; the temperature compensation layer is a silicon dioxide layer with a thickness of 25 to 80 nm.

[0016] The piezoelectric substrate layer is generally etched with two or more resonators connected in series to form a series resonator group and two or more resonators connected in parallel to form a parallel resonator group. The resonators corresponding to the series resonator group are called series resonators, and the resonators corresponding to the parallel resonator group are called parallel resonators. The number of resonators corresponding to the series resonator group and the parallel resonator group may be the same or different.

[0017] When the performance test of the temperature-compensated surface acoustic wave filter product finds that the bandwidth is less than the user's specification requirement, a silicon nitride layer is set on the upper surface of the temperature compensation layer corresponding to all the metal fingers of the series resonator, so as to increase the bandwidth of the temperature-compensated surface acoustic wave filter and avoid the scrapping or re-spinning of the temperature-compensated surface acoustic wave filter product.

[0018] When the performance test of the temperature-compensated surface acoustic wave filter product finds that the bandwidth is greater than the user's specification requirement, a silicon nitride layer is set on the upper surface of the temperature compensation layer corresponding to the metal fingers of all parallel resonators, thereby achieving the purpose of reducing the bandwidth of the temperature-compensated surface acoustic wave filter and avoiding the scrapping or re-spinning of the temperature-compensated surface acoustic wave filter product.

[0019] As for the thickness of the silicon nitride layer, it can be adjusted as needed.

[0020] The above-mentioned membrane structure is applied to a temperature-compensated surface acoustic wave filter. The useful 1db relative bandwidth of the communication system signal with a spectrum range of 400 to 600MHz is increased from 17Mhz to above 19Mhz, and the 15db relative bandwidth is reduced from 33MHZ to 31MHZ.

[0021] Finally, it should be noted that the above embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes and modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A membrane structure of a temperature-compensated surface acoustic wave filter, comprising a piezoelectric substrate layer, a temperature compensation layer and a plurality of resonators arranged on the piezoelectric substrate layer, wherein all resonators are composed of a plurality of series resonators and a plurality of parallel resonators, each resonator comprises a plurality of metal fingers, the temperature compensation layer is arranged on the upper surface of the resonator and covers the upper surface of the entire piezoelectric substrate layer, characterized in that: A bandwidth adjustment layer is provided on the upper surface of the temperature compensation layer corresponding to the metal fingers of all series resonators or parallel resonators, thereby achieving the purpose of increasing or decreasing the bandwidth of the temperature compensation surface acoustic wave filter.

2. The membrane structure of a temperature-compensated surface acoustic wave filter according to claim 1, characterized in that: The bandwidth adjustment layer is a silicon nitride layer.

3. A membrane structure of a temperature-compensated surface acoustic wave filter according to claim 1 or 2, characterized in that: The bandwidth adjustment layer has a thickness of 5-80 nm.

4. The membrane structure of a temperature-compensated surface acoustic wave filter according to claim 1, characterized in that: The temperature compensation layer is a silicon dioxide layer with a thickness of 25-80 nm.

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