Duplexer, preparation and improvement process thereof

Abstract

The invention discloses a duplexer and a preparation and improvement process thereof, and belongs to the field of filter devices, the isolation degree of a product is improved by adjusting the thickness difference of an insulating film in a Tx / Rx region of the duplexer, so that waste is turned into wealth, and the output rate is improved; meanwhile, according to the isolation requirement, duplexers meeting different frequency and power requirements can be produced, the problem of insufficient isolation does not need to be worried about, and the communication efficiency and stability are effectively guaranteed. And in the aspect of isolation, the output demand of zero waste is really realized.

Description

Technical Field

[0001] The present invention belongs to the field of filter devices, and in particular relates to a duplexer, a preparation method thereof and an improvement process thereof. Background Art

[0002] A duplexer is a specialized bidirectional three-terminal filter. It must couple weak receive signals while also delivering high transmit power to the antenna, each requiring its own functionality without interfering with the other. Traditional duplexers have a uniform insulating film thickness in both the Tx and Rx regions.

[0003] Traditional duplexers mainly use the following methods to improve the isolation of duplexers: 1. Adjust the thickness or film quality of the temperature supplementary layer SiO2; 2. Adjust the IDT film thickness / CD; 3. Change the device design, etc. Summary of the Invention

[0004] This invention addresses the temperature drift problem of existing surface acoustic wave filters by proposing a duplexer, its fabrication, and its improved process. By adjusting the difference in insulating film thickness between the Tx and Rx regions of the duplexer—that is, adjusting the frequency difference between them—this invention not only "turns waste into treasure," saving costs, but also reduces isolation differences between products.

[0005] In order to achieve the above-mentioned objectives, the present invention is implemented through the following technical solutions: a duplexer, comprising a substrate layer, an interdigitated electrode layer, a temperature compensation layer, an electrode layer and an insulating film layer, the interdigitated electrode layer is located above the substrate, the temperature compensation layer covers the interdigitated electrode layer, the suspended metal layer is located above the temperature compensation layer, the electrode layer is connected to the interdigitated electrode layer and the surface is exposed outside the temperature compensation layer, the insulating film layer covers the electrode layer and the suspended metal layer, the insulating film layer is divided into an Rx insulating film layer area and a Tx insulating film layer area, and the thickness of the Rx insulating film layer area is greater than or less than the thickness of the Tx insulating film layer area.

[0006] Furthermore, the difference between the thickness of the Rx insulating film layer region and the thickness of the Tx insulating film layer region is 2-50 nm.

[0007] Another technical solution protected by the present invention is: a process for preparing a duplexer, which is carried out according to the following steps: Step S1, prepare lithium niobate LN substrate material and clean it; Step S2, preparation of interdigitated electrode layer: coating, exposing and developing photoresist according to the interdigitated electrode pattern, so that the photoresist presents the corresponding interdigitated morphology, and then vacuum coating the interdigitated metal using a lift-off process to finally form the interdigitated electrode layer; Step S3, preparing a temperature compensation layer: preparing a temperature compensation layer by using a physical vapor deposition process; Step S4, preparation of suspended metal layer: according to the position and pattern of the suspended metal layer, photoresist coating, exposure, and development are performed to make the photoresist present the corresponding morphology; suspended metal vacuum coating is performed using a lift-off process to finally form a suspended metal layer; Step S5, electrode layer preparation: coating, exposing, and developing the photoresist of the electrode layer, so that the photoresist presents a corresponding morphology; vacuum coating the electrode metal using a lift-off process to finally form the electrode layer; Step S6, Tx insulating film layer area: photoresist coating, exposure, and development, exposing the Tx insulating film layer area to the outside, and forming the Tx insulating film layer by physical vapor deposition; Step S7, Rx insulating film layer area: photoresist coating, exposure, and development, exposing the Rx insulating film layer area to the outside, and preparing the Rx insulating film layer by physical vapor deposition.

[0008] Another technical solution protected by the present invention is a process for improving a duplexer, characterized by being carried out in accordance with the following steps: Step S1, duplexer after sputtering of insulating film layer; Step S2: coating, exposing, and developing photoresist, exposing the Tx or Rx region of the chip, and wrapping the Rx or Tx insulating film region with photoresist; Step S3: using dry etching to reduce the thickness of the Tx or Rx insulating film layer area; Step S4: remove the photoresist in the Rx or Tx insulating film layer area, and clean and dry it.

[0009] Compared with the existing technology, the beneficial effects of the present invention are as follows: the core innovation of the present invention lies in the use of insulating film layers of different thicknesses in the Tx area and the Rx area, so that the frequency difference between Tx and Rx can be adjusted, providing a way to improve the isolation of the duplexer design. For duplexers with higher isolation requirements, the isolation of the duplexer can be improved by using existing processes.

[0010] Furthermore, this method can also be applied to improving duplexer yield. After traditional duplexer manufacturing, some products have to be scrapped because their isolation doesn't meet established requirements, wasting costs and resulting in a loss of yield. However, the process of the present invention, by adjusting the difference in insulating film thickness between the Tx and Rx regions of the duplexer—that is, adjusting the frequency difference between the two—can not only "turn waste into treasure" and save costs, but also reduce the isolation differences between products. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the structure of the duplexer of the present invention.

[0012] Figure 2The figure is a comparison of Tx / Rx before and after improvement by the process of the present invention.

[0013] Figure 3 This is a comparison diagram of isolation before and after improvement using the process of the present invention. DETAILED DESCRIPTION

[0014] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings and examples, so as to fully understand and implement the process of how the present invention applies technical means to solve technical problems and achieve technical effects.

[0015] like Figure 1 As shown, a duplexer includes a substrate layer, an interdigitated electrode layer, a temperature compensation layer, an electrode layer, and an insulating film layer. The interdigitated electrode layer is located above the substrate, the temperature compensation layer covers the interdigitated electrode layer, the suspended metal layer is located above the temperature compensation layer, the electrode layer is connected to the interdigitated electrode layer and the surface is exposed outside the temperature compensation layer, the insulating film layer covers the electrode layer and the suspended metal layer, and the insulating film layer is divided into an Rx insulating film layer region and a Tx insulating film layer region. The thickness of the Rx insulating film layer region is greater than or less than the thickness of the Tx insulating film layer region.

[0016] There is a strong positive correlation between the thickness of the insulating layer and the Tx / Rx frequency of the filter. By adjusting the thickness difference of the Tx / Rx insulating film, the frequency difference between Tx / Rx can be adjusted in disguise, so the filter isolation can be adjusted.

[0017] The thickness difference between the Rx and Tx insulating film regions is typically 2 to 50 nm (the specific thickness difference depends on the device's design and performance). This thickness difference should not be too large, as it can lead to uneven heat dissipation and poor frequency stability, which in turn affects the device's filtering performance.

[0018] The structure and principle of the duplexer of the present invention are briefly introduced above. The preparation process of the duplexer is described in detail below. A preparation process of the duplexer is carried out according to the following steps: Step S1, prepare lithium niobate LN substrate material and clean it; Step S2, preparation of interdigitated electrode layer: coating, exposing and developing photoresist according to the interdigitated electrode pattern, so that the photoresist presents the corresponding interdigitated morphology, and then vacuum coating the interdigitated metal using a lift-off process to finally form the interdigitated electrode layer; Step S3, preparing a temperature compensation layer: preparing a temperature compensation layer by using a physical vapor deposition process; Step S4, preparation of suspended metal layer: according to the position and pattern of the suspended metal layer, photoresist coating, exposure, and development are performed to make the photoresist present the corresponding morphology; suspended metal vacuum coating is performed using a lift-off process to finally form a suspended metal layer; Step S5, electrode layer preparation: coating, exposing, and developing the photoresist of the electrode layer, so that the photoresist presents a corresponding morphology; vacuum coating the electrode metal using a lift-off process to finally form the electrode layer; Step S6, Tx insulating film layer area: photoresist coating, exposure, and development, exposing the Tx insulating film layer area to the outside, and forming the Tx insulating film layer by physical vapor deposition; Step S7, Rx insulating film layer area: photoresist coating, exposure, and development, exposing the Rx insulating film layer area to the outside, and preparing the Rx insulating film layer by physical vapor deposition.

[0019] The duplexer fabrication process of the present invention is slightly more complex than traditional duplexer fabrication processes, primarily due to the preparation of the insulating film layer, which requires two steps: first preparing the Tx insulating film layer region and then the Rx insulating film layer region. While this process increases the number of steps, it significantly improves the duplexer's isolation. This invention is suitable for duplexer fabrication processes requiring high isolation. By adding the present invention's process of varying the thickness of the insulating film layers in the Tx and Rx regions, in addition to existing processes for improving duplexer isolation, it further improves duplexer isolation.

[0020] In addition to being applied to the preparation of new duplexers, the innovation of the present invention can also be applied to the improvement of defective existing duplexers. A duplexer improvement process is performed according to the following steps: Step S1, duplexer after sputtering of insulating film layer; Step S2: coating, exposing, and developing photoresist, exposing the Tx (or Rx) region of the chip, and wrapping the Rx (or Tx) insulating film region with photoresist; Step S3: using dry etching to reduce the thickness of the Tx (or Rx) insulating film layer area; Step S4: remove the photoresist in the Rx (or Tx) insulating film layer area, and clean and dry it.

[0021] like Figure 3 As shown, after using the improved process of the present invention, the isolation of the duplexer is significantly improved, and the ISO is improved by about 10 MHz.

[0022] This invention improves product isolation by adjusting the thickness difference of the insulating film in the Tx / Rx regions of the duplexer, thereby turning waste into treasure and increasing output. Furthermore, duplexers can be produced to suit different frequencies and power requirements, eliminating the need for isolation issues and effectively ensuring efficient and stable communications. This truly achieves zero-waste output in terms of isolation.

[0023] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A duplexer, characterized in that: It includes a substrate layer, an interdigitated electrode layer, a temperature compensation layer, an electrode layer and an insulating film layer. The interdigitated electrode layer is located above the substrate, the temperature compensation layer covers the interdigitated electrode layer, the suspended metal layer is located above the temperature compensation layer, the electrode layer is connected to the interdigitated electrode layer and the surface is exposed outside the temperature compensation layer, the insulating film layer covers the electrode layer and the suspended metal layer, and the insulating film layer is divided into an Rx insulating film layer area and a Tx insulating film layer area. The thickness of the Rx insulating film layer area is greater than or less than the thickness of the Tx insulating film layer area.

2. The duplexer according to claim 1, wherein: The difference between the thickness of the Rx insulating film layer region and the thickness of the Tx insulating film layer region is 2-50 nm.

3. A process for preparing a duplexer, characterized in that: Follow these steps: Step S1, prepare lithium niobate LN substrate material and clean it; Step S2, preparation of interdigitated electrode layer: coating, exposing and developing photoresist according to the interdigitated electrode pattern, so that the photoresist presents the corresponding interdigitated morphology, and then vacuum coating the interdigitated metal using a lift-off process to finally form the interdigitated electrode layer; Step S3, preparing a temperature compensation layer: preparing a temperature compensation layer by using a physical vapor deposition process; Step S4, preparation of the suspended metal layer: performing photoresist coating, exposure, and development according to the position and pattern of the suspended metal layer, so that the photoresist presents a corresponding morphology; Suspended metal vacuum coating uses lift-off process to finally suspend the metal layer; Step S5, electrode layer preparation: coating, exposing, and developing the photoresist of the electrode layer, so that the photoresist presents a corresponding morphology; Electrode metal vacuum coating, using lift-off process, ultimately forms the electrode layer; Step S6, Tx insulating film layer area: photoresist coating, exposure, and development, exposing the Tx insulating film layer area to the outside, and forming the Tx insulating film layer by physical vapor deposition; Step S7, Rx insulating film layer area: photoresist coating, exposure, and development, exposing the Rx insulating film layer area to the outside, and preparing the Rx insulating film layer by physical vapor deposition.

4. A process for improving a duplexer, characterized in that: Follow these steps: Step S1, duplexer after sputtering of insulating film layer; Step S2: coating, exposing, and developing photoresist, exposing the Tx or Rx region of the chip, and wrapping the Rx or Tx insulating film region with photoresist; Step S3: using dry etching to reduce the thickness of the Tx or Rx insulating film layer area; Step S4: remove the photoresist in the Rx or Tx insulating film layer area, and clean and dry it.

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