High-performance surface acoustic wave filter

Abstract

The utility model discloses a surface acoustic wave filter with high performance, which comprises a substrate layer, a piezoelectric layer and a resonator metal layer, the piezoelectric layer is arranged above the substrate layer, the resonator metal layer is arranged above the piezoelectric layer, and the resonator metal layer is arranged above the piezoelectric layer. The upper surface of an electrode connecting area in the resonator metal layer is further covered with a covering metal layer, a channel cavity is further formed in the portion, below the resonator metal layer, of the substrate layer, and the range of the channel cavity covers the interdigital transducer of the resonator metal layer. The surface acoustic wave filter can obstruct the transmission of body waves and improve the tolerance power at the same time.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of high-performance surface acoustic wave filter, belong to surface acoustic wave filter technical field. BACKGROUND

[0002] In recent years, with the rapid development of mobile communication technology, the number of surface acoustic wave filter (Surface Acoustic Wave) required in electronic products, such as mobile phones, base stations, etc. also increases rapidly, which puts new demands and challenges on the performance of SAW filter. At present, the withstand power and insertion loss of SAW filter still have deficiencies, mainly due to the small size of the filter, the heat dissipation performance is insufficient, and the energy leaks to the substrate due to the body wave. SUMMARY

[0003] The technical problem to be solved by the utility model is to provide a high-performance surface acoustic wave filter that can block the transmission of body waves while improving the withstand power.

[0004] To solve the first technical problem, the technical solution of the utility model is: a high-performance surface acoustic wave filter, comprising a substrate layer, a piezoelectric layer and a resonator metal layer, the piezoelectric layer is arranged above the substrate layer, the resonator metal layer is arranged above the piezoelectric layer, the upper surface of the electrode connection area in the resonator metal layer is also covered with a covering metal layer, and the substrate layer below the resonator metal layer is also provided with a channel cavity, the range of the channel cavity covers the interdigital transducer of the resonator metal layer.

[0005] As a preferred scheme, the bottom of the piezoelectric layer within the range of the channel cavity is provided with an upper heat-conducting metal layer, the two sides of the upper heat-conducting metal layer are supported by the piezoelectric layer, and the upper surface of the upper heat-conducting metal layer is flush with the upper surface of the piezoelectric layer.

[0006] As a preferred scheme, the side wall and bottom wall of the channel cavity are also covered with a side heat-conducting metal layer and a lower heat-conducting metal layer respectively, the bottom of the piezoelectric layer within the range of the channel cavity is provided with an upper heat-conducting metal layer, the two sides of the upper heat-conducting metal layer are supported by the piezoelectric layer, the upper surface of the upper heat-conducting metal layer is flush with the upper surface of the piezoelectric layer, and the upper heat-conducting metal layer is connected with the side heat-conducting metal layer and the lower heat-conducting metal layer.

[0007] As a preferred scheme, the thickness of the upper heat-conducting metal layer and the lower heat-conducting metal layer is the same and greater than or equal to the side heat-conducting metal layer.

[0008] As a preferred scheme, the upper heat-conducting metal layer, the lower heat-conducting metal layer and the side heat-conducting metal layer are made of the same material selected from the group consisting of gold, silver, copper, aluminum, chromium and titanium, or an alloy or a composite layer of the above-mentioned elements.

[0009] As a preferred scheme, the cross section of the channel cavity is an inverted trapezoid.

[0010] As a preferred scheme, the substrate layer comprises a first substrate layer below and a second substrate layer above, and the channel cavity is arranged on the second substrate layer.

[0011] As a preferred scheme, the first substrate layer is a high-resistance silicon layer, and the second substrate layer is one or more of silicon dioxide, silicon nitride and silicon oxynitride.

[0012] After the above technical scheme is adopted, the utility model has the following effects: the upper surface of the electrode connecting area in the resonator metal layer is further covered with a covering metal layer, the cross-sectional area of the electrode connecting area as a whole is relatively large because the covering metal layer does not need to consider the piezoelectric conversion effect, the loss of signal transmission energy in the area is relatively small, and thus the resistivity can be reduced; the channel cavity is further arranged below the resonator metal layer on the substrate layer, the range of the channel cavity covers the interdigital transducer of the resonator metal layer, and the existence of the channel cavity can block the downward transmission of the bulk wave, thereby improving the quality factor of the filter.

[0013] In addition, the bottom of the piezoelectric layer in the range of the channel cavity is provided with an upper heat-conducting metal layer, the two sides of the upper heat-conducting metal layer are supported by the piezoelectric layer, the upper surface of the upper heat-conducting metal layer is flush with the upper surface of the piezoelectric layer, and thus when the resonator metal layer passes through a high-power signal, a large amount of heat is generated, which is transmitted to the surrounding environment, and then transmitted to the upper heat-conducting metal layer after passing through the piezoelectric layer, and the upper heat-conducting metal layer can provide good heat dissipation, thereby increasing the tolerance power of the resonator.

[0014] In addition, the side wall and the bottom wall of the channel cavity are further covered with a side heat-conducting metal layer and a lower heat-conducting metal layer respectively, the bottom of the piezoelectric layer in the range of the channel cavity is provided with an upper heat-conducting metal layer, the two sides of the upper heat-conducting metal layer are supported by the piezoelectric layer, the upper surface of the upper heat-conducting metal layer is flush with the upper surface of the piezoelectric layer, and the upper heat-conducting metal layer is connected with the side heat-conducting metal layer and the lower heat-conducting metal layer, and similarly, the heat generated by the resonator metal layer can be better transmitted to the side heat-conducting metal layer and the lower heat-conducting metal layer through the upper heat-conducting metal layer, and finally transmitted to the substrate layer, thereby improving the heat conduction performance, and the structure has good heat dissipation performance, and the tolerance power of the resonator metal layer is greatly improved.

[0015] And since the cross section of the channel cavity is an inverted trapezoid, the upper part of the channel cavity is wide and the lower part is narrow, so that the width of the upper heat-conducting metal layer is sufficient to cover the resonator metal layer while the channel cavity is not too large. Thus, the support of the overall structure is relatively reliable.

[0016] In addition, the utility model discloses a kind of forming method of high-performance surface acoustic wave filter, which is used to form the high-performance surface acoustic wave filter described above, comprising the following steps:

[0017] S1, provide substrate layer, and form channel cavity by gas deposition or sputtering process;

[0018] S2, fill the sacrificial layer in channel cavity;

[0019] S3, form a layer of metal on the upper surface of the sacrificial layer by gas deposition or sputtering process to form an upper heat-conducting metal layer, and the surface of the upper heat-conducting metal layer is flush with the upper surface of the substrate layer;

[0020] S4, make a through hole in the upper heat-conducting metal layer, and lead out the sacrificial layer in the through hole cavity;

[0021] S5, bond the piezoelectric wafer to the surface of the substrate layer and the upper heat-conducting metal layer by crystal ion implantation stripping technology to form a piezoelectric layer;

[0022] S6, generate resonator metal layer and cover metal layer on the surface of the piezoelectric layer by photolithography process.

[0023] Preferably, step S1 and step S2 are further increased between step S1-2, which is to generate lower heat-conducting metal layer and side heat-conducting metal layer on the surface of the channel cavity by gas deposition or sputtering process.

[0024] After adopting the above technical scheme, the effect of the utility model is that the forming method can block the transmission of bulk waves and improve the power tolerance. BRIEF DESCRIPTION OF DRAWINGS

[0025] The utility model will be further described below in combination with the drawings and examples.

[0026] Figure 1 It is the structure schematic diagram of the utility model embodiment 1;

[0027] Figure 2 It is the structure schematic diagram of the utility model embodiment 1;

[0028] In the drawings: 10, cover metal layer;20, piezoelectric layer;30, second substrate layer;40, first substrate layer;50, channel cavity;60, resonator metal layer;70, upper heat-conducting metal layer;80, side heat-conducting metal layer;90, lower heat-conducting metal layer. Detailed Implementation

[0029] The present invention will be further described in detail below through specific embodiments.

[0030] Example 1

[0031] like Figure 1 As shown, a high-performance surface acoustic wave (SAW) filter includes a substrate, a piezoelectric layer 20, and a resonator metal layer 60. The piezoelectric layer 20 is disposed above the substrate, and the resonator metal layer 60 is disposed above the piezoelectric layer 20. The resonator metal layer 60 includes interdigital transducers and reflective gratings disposed on both sides of the interdigital transducers. The upper surface of the electrode connection region in the resonator metal layer 60 is further covered by a cover metal layer 10, which increases the cross-sectional area of ​​the electrode connection region, thereby reducing resistivity and reducing power transmission loss. A channel cavity 50 is also disposed on the substrate below the resonator metal layer 60, and the channel cavity 50 covers the interdigital transducers of the resonator metal layer 60.

[0032] In this embodiment, the piezoelectric layer 20 is provided with an upper thermally conductive metal layer 70 at the bottom of the channel cavity 50. The upper thermally conductive metal layer 70 is supported on both sides by the piezoelectric layer 20, and the upper surface of the upper thermally conductive metal layer 70 is flush with the upper surface of the piezoelectric layer 20.

[0033] The upper thermally conductive metal layer 70 is selected from gold, silver, copper, aluminum, chromium, and titanium, or an alloy or composite layer of the above-mentioned elements. The piezoelectric layer 20 can be selected from piezoelectric materials such as lithium tantalate and lithium niobate.

[0034] like Figure 1 As shown, in this embodiment, the cross-section of the channel cavity 50 is an inverted trapezoid.

[0035] The substrate layer includes a first substrate layer 40 located below and a second substrate layer 30 located above, and the channel cavity 50 is disposed on the second substrate layer 30. The first substrate layer 40 is a high-resistivity silicon layer, which also has good thermal conductivity. The second substrate layer 30 is one or more of silicon dioxide, silicon nitride, and silicon oxynitride.

[0036] The filter forming method in this embodiment is as follows: S1, a substrate layer is provided, and a channel cavity 50 is formed by vapor deposition or sputtering process; wherein, since the substrate layer includes a first substrate layer 40 and a second substrate layer 30, the channel cavity 50 can be formed by directly forming a second substrate layer on the first substrate layer by vapor deposition or sputtering process, thereby forming the channel cavity 50.

[0037] S2. Fill the channel cavity 50 with a sacrificial layer;

[0038] S3, forming an upper heat-conductive metal layer 70 on the upper surface of the sacrificial layer by a vapor deposition or sputtering process, the surface of the upper heat-conductive metal layer 70 being flush with the upper surface of the substrate layer;

[0039] S4, making a through hole in the upper heat-conductive metal layer 70 and leading out the sacrificial layer in the through hole cavity;

[0040] S5, bonding the piezoelectric wafer to the surface of the substrate layer and the upper heat-conductive metal layer 70 by a crystal ion implantation stripping technique to form the piezoelectric layer 20;

[0041] S6, generating the resonator metal layer 60 and the cover metal layer 10 on the surface of the piezoelectric layer 20 by a photolithography process.

[0042] Among them, the vapor deposition, sputtering process, crystal ion implantation stripping technique and photolithography process are all conventional mature processes of semiconductors, which will not be described in detail.

[0043] Example Two

[0044] The basic structure of this embodiment is the same as that of Example One, except that in this embodiment, the side wall and bottom wall of the channel cavity 50 are further covered with a side heat-conductive metal layer 80 and a lower heat-conductive metal layer 90, respectively, the piezoelectric layer 20 is located at the bottom of the channel cavity 50 within the range of the upper heat-conductive metal layer 70, the two sides of the upper heat-conductive metal layer 70 are supported by the piezoelectric layer 20, the upper surface of the upper heat-conductive metal layer 70 is flush with the upper surface of the piezoelectric layer 20, and the upper heat-conductive metal layer 70 is connected with the side heat-conductive metal layer 80 and the lower heat-conductive metal layer 90.

[0045] Among them, the thickness of the upper heat-conductive metal layer 70 and the lower heat-conductive metal layer 90 is the same and greater than or equal to the side heat-conductive metal layer 80. The materials of the upper heat-conductive metal layer 70, the lower heat-conductive metal layer 90 and the side heat-conductive metal layer 80 are the same and are selected from the group consisting of gold, silver, copper, aluminum, chromium, titanium, or alloys or composite layers of the above-mentioned single elements.

[0046] The forming method in this embodiment is to add a step S1-2 between the step S1 and the step S2 in the forming method of Example One, which is to generate a lower heat-conductive metal layer 90 and a side heat-conductive metal layer 80 on the surface of the channel cavity 50 by a vapor deposition or sputtering process. After the lower heat-conductive metal layer 90 and the side heat-conductive metal layer 80 are formed, the sacrificial layer is filled, and then the subsequent steps are continued to finally form the filter in the Figure 2

[0047] ​The scheme in the utility model has at least the following advantages relative to the conventional filter method: 1. The upper surface of the electrode connecting area is further covered with a covering metal layer 10, so that the thickness of the electrode connecting area is increased, the cross-sectional area is increased, and the resistivity is reduced, so that the transmission loss of power is reduced; 2. The channel cavity 50 is arranged, the transmission of the bulk wave is blocked, and the quality factor of the filter is improved; 3. The upper heat-conducting metal layer 70, the lower heat-conducting metal layer 90 and the side heat-conducting metal layer 80 are arranged, the heat-conducting performance is improved, and the heat dissipation during high-power signal filtering is met.

[0048] The above-described embodiments are only preferred embodiments of the utility model, and do not limit the scope of the utility model. Various modifications and improvements of the technical scheme of the utility model made without departing from the design spirit of the utility model shall fall within the protection scope defined by the claims of the utility model.

Claims

1. A high performance surface acoustic wave filter comprising a substrate layer, a piezoelectric layer disposed above the substrate layer, and a resonator metal layer disposed above the piezoelectric layer, characterized by: The upper surface of the electrode connecting area in the resonator metal layer is further covered with a covering metal layer, and a channel cavity is further arranged on the substrate layer below the resonator metal layer, and the channel cavity covers the interdigital transducer of the resonator metal layer.

2. A high performance surface acoustic wave filter as claimed in claim 1, characterized in that: The bottom of the piezoelectric layer in the range of the channel cavity is provided with an upper heat-conducting metal layer, both sides of the upper heat-conducting metal layer are supported by the piezoelectric layer, and the upper surface of the upper heat-conducting metal layer is flush with the upper surface of the piezoelectric layer.

3. A high performance surface acoustic wave filter as claimed in claim 1, characterized in that: The side wall and the bottom wall of the channel cavity are further covered with a side heat-conducting metal layer and a lower heat-conducting metal layer respectively, the bottom of the piezoelectric layer in the range of the channel cavity is provided with an upper heat-conducting metal layer, both sides of the upper heat-conducting metal layer are supported by the piezoelectric layer, the upper surface of the upper heat-conducting metal layer is flush with the upper surface of the piezoelectric layer, and the upper heat-conducting metal layer is connected with the side heat-conducting metal layer and the lower heat-conducting metal layer.

4. A high performance surface acoustic wave filter as claimed in claim 3, characterized in that: The thickness of the upper heat-conducting metal layer and the lower heat-conducting metal layer is the same and greater than or equal to the thickness of the side heat-conducting metal layer.

5. A high performance surface acoustic wave filter as claimed in claim 4, characterized in that: The upper heat-conducting metal layer, the lower heat-conducting metal layer and the side heat-conducting metal layer are made of the same material selected from the group consisting of gold, silver, copper, aluminum, chromium, titanium, alloys of the above-mentioned elements and composite layers of the above-mentioned elements.

6. A high performance surface acoustic wave filter as claimed in claim 1, characterized in that: The cross section of the channel cavity is an inverted trapezoid.

7. A high performance surface acoustic wave filter as recited in claim 1, wherein: The substrate layer comprises a first substrate layer below and a second substrate layer above, and the channel cavity is arranged on the second substrate layer.

8. A high performance surface acoustic wave filter as claimed in claim 7, characterized in that: The first substrate layer is a high-resistance silicon layer, and the second substrate layer is one or more of silicon dioxide, silicon nitride and silicon oxynitride.

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