CN-122001334-A - Temperature compensation type surface acoustic wave filter and manufacturing method thereof

CN122001334ACN 122001334 ACN122001334 ACN 122001334ACN-122001334-A

Abstract

The application provides a temperature compensation type surface acoustic wave filter and a manufacturing method thereof, comprising a piezoelectric substrate, an IDT electrode formed on the piezoelectric substrate, the piezoelectric substrate comprises a piezoelectric substrate, a first temperature compensation layer and at least one group of composite layers, wherein the piezoelectric substrate is provided with an IDT electrode, the first temperature compensation layer is formed on the piezoelectric substrate and covers the IDT electrode, and one side of each composite layer, which is far away from the piezoelectric substrate, contains fluorine. According to the application, fluorine element doping is performed in a specific area of the composite layer, so that the problems of large frequency drift, poor performance stability and narrow temperature-domain adaptation core pain point of a single SiO 2 temperature compensation layer in a wide temperature domain of a traditional surface acoustic wave filter are systematically solved, high-precision compensation and depth optimization of TCF (thermal conductivity) of less than or equal to-20 ppm/° C are realized, and meanwhile, the composite layer has cost controllability and large-scale production capacity, and extremely strong technical innovation and industrial application value.

Inventors

ZHANG JINGYING
WANG YUANYUAN
ZHANG SHUMIN

Assignees

左蓝微(江苏)电子技术有限公司

Dates

Publication Date: 20260508
Application Date: 20251226

Claims (14)

1. A temperature-compensated surface acoustic wave filter comprising: a piezoelectric substrate; An IDT electrode on the piezoelectric substrate; The first temperature compensation layer is positioned on the piezoelectric substrate and covers and wraps the IDT electrode; And at least one group of composite layers are positioned on the first temperature compensation layer, and one side of each composite layer, which is far away from the piezoelectric substrate, contains fluorine.
2. The temperature-compensated surface acoustic wave filter according to claim 1, wherein the composite layer comprises a fluorine barrier layer and a second temperature compensation layer stacked in this order from bottom to top, the fluorine element being doped in the second temperature compensation layer.
3. The temperature-compensated surface acoustic wave filter according to claim 2, wherein the content of fluorine element in the second temperature-compensated layer is not more than 10%.
4. The temperature-compensated surface acoustic wave filter of claim 2, wherein the thickness of the second temperature compensation layer on the piezoelectric substrate is greater than the thickness of the first temperature compensation layer on the piezoelectric substrate.
5. The temperature-compensated surface acoustic wave filter according to claim 2, wherein the thickness of the second temperature compensation layer is in a range of 1 to 7 times the thickness of the first temperature compensation layer.
6. The temperature-compensated surface acoustic wave filter of claim 2 wherein the fluorine barrier layer has a thickness in the range of not more than 30nm over the first temperature-compensated layer.
7. The temperature-compensated surface acoustic wave filter according to claim 2, wherein the constituent material of the fluorine barrier layer includes one of silicon nitride, silicon carbide, silicon oxynitride, or aluminum oxide.
8. The temperature-compensated surface acoustic wave filter according to claim 1, wherein a thickness of the first temperature compensation layer on the piezoelectric substrate is not lower than a thickness of the IDT electrode on the piezoelectric substrate.
9. The temperature-compensated surface acoustic wave filter according to claim 2, wherein the number of the composite layers includes a plurality of groups, and a plurality of groups of the composite layers are stacked in order on the first temperature-compensated layer.
10. The temperature-compensated surface acoustic wave filter according to claim 9, wherein fluorine element content in the second temperature-compensated layer in the different composite layers is the same.
11. The temperature-compensated surface acoustic wave filter according to claim 9, wherein fluorine content in the second temperature compensation layer in the different composite layers is different.
12. A method for manufacturing a temperature-compensated surface acoustic wave filter is characterized by comprising the following steps: providing a piezoelectric substrate; Forming an IDT electrode on the piezoelectric substrate; forming a first temperature compensation layer on the piezoelectric substrate, wherein the first temperature compensation layer covers and wraps the IDT electrode; And forming at least one group of composite layers on the first temperature compensation layer, wherein the composite layers comprise a fluorine barrier layer and a second temperature compensation layer which are sequentially stacked from bottom to top, and the second temperature compensation layer contains fluorine element.
13. The method of manufacturing a temperature-compensated surface acoustic wave filter according to claim 12, wherein the step of forming the second temperature-compensated layer on the fluorine barrier layer comprises forming the second temperature-compensated layer by a plasma-enhanced gas chemical vapor deposition method and using silicon fluoride as a fluorine source doped with fluorine.
14. The method of manufacturing a temperature-compensated surface acoustic wave filter according to claim 12, wherein the step of forming at least one set of composite layers on the first temperature-compensated layer comprises: and forming a plurality of groups of composite layers on the first temperature compensation layer, and sequentially stacking the plurality of groups of composite layers to form a stacked body.

Description

Temperature compensation type surface acoustic wave filter and manufacturing method thereof Technical Field The application relates to the technical field of semiconductor production processes, in particular to a temperature compensation type surface acoustic wave filter and a manufacturing method thereof. Background Temperature-compensated surface acoustic wave (Temperature Compensation Surface Acoustic Wave, TC)SAW) devices are used as core components of radio frequency communication systems, and the frequency temperature stability of the SAW devices directly affects the transmission accuracy and reliability of communication signals. The Temperature Compensation (TC) layer of the prior TCSAW device generally adopts a single silicon dioxide (SiO 2) material system, and utilizes the principle that the temperature drift characteristic of the surface acoustic wave in a SiO 2 medium and the temperature response of a substrate wafer are in inverse relation to realize the compensation optimization of the frequency temperature coefficient of the device, thereby improving the frequency temperature coefficient of the common surface acoustic wave device and enhancing the temperature adaptability of the device. However, with the evolution of the 4G/5G communication technology and the development of integration of the radio frequency front end module, the communication terminal and the base station device put higher demands on the performance index of TCSAW devices, especially in terms of frequency temperature stability, the prior art has been difficult to meet the severe demands of the system-level application. In particular, the frequency temperature coefficient achieved by the current TCSAW device based on a single SiO 2 temperature compensation layer cannot be matched with the technical specifications of high-end communication scenes, so that the frequency precision and the long-term reliability of the device under the wide-temperature-range working condition are obviously limited. This bottleneck has become a key obstacle to further application of TCSAW devices in the high-end communication field, and it is highly desirable to realize deep optimization of frequency temperature coefficient through technical improvement. Disclosure of Invention The present application aims to solve at least one of the technical problems in the related art to some extent. Therefore, a first object of the present application is to provide a temperature-compensated surface acoustic wave filter and a method for manufacturing the same, which can improve the frequency temperature coefficient of TCSAW devices to be within-20 ppm/°c, thereby meeting the further application requirements of TCSAW devices in the high-end communication field. To achieve the above object, an embodiment of a first aspect of the present application provides a temperature-compensated surface acoustic wave filter, including: a piezoelectric substrate; An IDT electrode on the piezoelectric substrate; The first temperature compensation layer is positioned on the piezoelectric substrate and covers and wraps the IDT electrode; And at least one group of composite layers are positioned on the first temperature compensation layer, and one side of each composite layer, which is far away from the piezoelectric substrate, contains fluorine. Optionally, the composite layer comprises a fluorine barrier layer and a second temperature compensation layer which are sequentially stacked from bottom to top, and the fluorine element is doped in the second temperature compensation layer. Optionally, the content of the fluorine element in the second temperature compensation layer is not more than 10%. Optionally, the thickness of the second temperature compensation layer on the piezoelectric substrate is greater than the thickness of the first temperature compensation layer on the piezoelectric substrate. Optionally, the thickness range of the second temperature compensation layer is 1-7 times of the thickness of the first temperature compensation layer. Optionally, a thickness of the fluorine barrier layer on the first temperature compensation layer ranges from no more than 30nm. Optionally, the composition material of the fluorine barrier layer includes one of silicon nitride, silicon carbide, silicon oxynitride, or aluminum oxide. Optionally, the thickness of the first temperature compensation layer on the piezoelectric substrate is not lower than the thickness of the IDT electrode on the piezoelectric substrate. Optionally, the number of the composite layers includes a plurality of groups, and the plurality of groups of the composite layers are sequentially stacked on the first temperature compensation layer. Optionally, the fluorine element content in the second temperature compensation layer in the different composite layers is the same. Optionally, the fluorine element content in the second temperature compensation layer in the different composite layers is not the same. In orde