JP2018110379A - Method for fabricating bulk acoustic wave resonator with mass adjustment structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for fabricating a bulk acoustic wave resonator which enables the decrease in spurious mode.SOLUTION: A method for fabricating a bulk acoustic wave resonator 1 with a mass adjustment structure comprises the steps of: forming a sacrificial mesa structure on a substrate 10; etching the sacrificial mesa structure such that any two adjacent parts of the sacrificial mesa structure have different heights, and a top surface of a highest part of the sacrificial structure mesa is coincident with a mesa top extending plane; forming an insulating layer 11 on the sacrificial mesa structure and the substrate; polishing the insulating layer to form a polished surface 41; forming, on the polished surface, a bulk acoustic wave resonance structure 300 including a top electrode 32, a piezoelectric layer 31 and a bottom electrode layer 30; and etching the sacrificial mesa structure to form a cavity. In the method, the insulating layer between the polished surface and the mesa top extending plane forms a frequency tuning structure, and the insulating layer between the mesa top extending plane and the cavity forms the mass adjustment structure.SELECTED DRAWING: Figure 6C

Description

  The present application relates to a method of manufacturing a bulk acoustic wave resonance device with a mass adjustment structure. In particular, the present invention relates to a method of manufacturing a bulk acoustic wave resonance device with a mass adjustment structure and a frequency adjustment structure.

  Please refer to FIG. This is a drawing for explaining an embodiment of an existing bulk acoustic wave resonator. The resonance device includes a substrate 90, a bottom electrode 91, a piezoelectric layer 92, an upper electrode 93, a hole 94, and an annular piezoelectric layer groove 95. The bottom electrode 91 is formed on the substrate 90. The piezoelectric layer 92 is formed on the bottom electrode 91. The upper electrode 93 is formed on the piezoelectric layer 92. The holes 94 are formed above the substrate 90 and below the bottom electrode 91. A resonance film of the bulk acoustic wave resonance device is formed by the overlapping portion of the upper electrode 93, the piezoelectric layer 92, and the bottom electrode 91. The annular piezoelectric layer groove 95 is formed by removing the members constituting the piezoelectric layer 92 along the periphery of the resonant film of the bulk acoustic wave resonator. By forming the annular piezoelectric layer groove 95, the boundary condition around the resonant film of the bulk acoustic wave resonator changes. Since the boundary condition of the periphery of the resonant film of the bulk acoustic wave resonator is changed, when the incident acoustic wave is reflected by the peripheral portion of the resonant film of the bulk acoustic wave resonator, the ratio of the reflected acoustic wave to the incident acoustic wave is adjusted. Can do. Therefore, by designing and fine-tuning the width and depth of the annular piezoelectric layer groove 95, the Q factor of the bulk acoustic wave resonator can be enhanced by adjusting the ratio of the reflected acoustic wave and the incident acoustic wave.

  Usually, the width of the resonance film of the bulk acoustic wave resonator is formed by the upper electrode 93, the piezoelectric layer 92 and the bottom electrode 91, and the width is much larger than the depth of the hole 94. In particular, since the upper electrode 93 and the bottom electrode 91 are made of metal, when stress is applied, the resonant film of the bulk acoustic wave resonator is bent downward. Thus, there is a risk that the bottom of the bottom electrode 91 touches the substrate 90 (the bottom of the hole 94) and the characteristics of the bulk acoustic wave resonance device are affected. Further, by removing the member of the piezoelectric layer 92 in the vicinity of the periphery of the resonance film of the bulk acoustic wave resonance device that forms the annular piezoelectric layer groove 95, the mechanical structure strength of the resonance film of the bulk acoustic wave resonance device is impaired and stress is reduced. This makes it easier for the resonant film to bend downward. Furthermore, if the mechanical structure strength of the resonance film of the bulk acoustic wave resonator is insufficient, the resonance film may be collapsed.

  Since the acoustic wave travels in the resonance film of the bulk acoustic wave resonator and resonates, the overall flatness of the top electrode 93, the piezoelectric layer 92, and the bottom electrode 91 of the resonance film directly affects the characteristics of the bulk acoustic wave resonator. Affect. In another embodiment of the prior art bulk acoustic wave resonator, a raised structure is formed along the top surface edge of the bottom electrode 91. By forming such a raised structure, the boundary condition of the periphery of the resonant film of the bulk acoustic wave resonator changes, and the ratio of the reflected acoustic wave to the incident acoustic wave can be adjusted. Thus, by designing and adjusting the raised structure, the ratio of the reflected acoustic wave to the incident acoustic wave can be adjusted, and the Q factor of the bulk acoustic wave resonance device is enhanced. However, the formation of the raised structure along the edge of the upper surface of the bottom electrode 91 may impair the flatness of the piezoelectric layer 92 and may affect the flatness of the entire resonant film of the bulk acoustic wave resonator. is there. Thus, the characteristics of the acoustic wave traveling through the resonant film of the bulk acoustic wave resonator will be affected, and the characteristics of the bulk acoustic wave resonator will be adversely affected.

Therefore, the present application has developed a new structure that avoids the above-described drawbacks, greatly improves device characteristics, and takes into account economic efficiency. Therefore, the present invention is proposed here.

  The main technical problem to be solved by the present application is to improve the mechanical strength of the resonance film of the bulk acoustic wave resonance device, eliminate the influence on the flattening of the entire surface of the resonance film, and as a result, spurious of the bulk acoustic wave resonance device. To reduce the mode.

In order to solve the above problems and obtain an expected effect, the present application provides a method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure, which includes the following steps.
Step D1: A sacrificial mesa structure divided into a plurality of parts is formed on a substrate.
Step D2: Etch the mesa structure such that any two adjacent portions of the sacrificial mesa structure have different heights. Here, the uppermost portion of the sacrificial mesa structure has the highest mesa upper surface. The top surface of the highest mesa coincides with the top of the entire mesa.
Step D3: forming an insulating layer on the sacrificial mesa structure and the substrate.
Step D4: The insulating layer is polished by a chemical mechanical planarization process to form a polished surface.
Step D5: forming a bulk acoustic wave resonance structure on the polished surface. However, the bulk acoustic wave resonance structure is located on the sacrificial mesa structure. Further, this step D5 comprises the following steps.
Step D51: forming a bottom electrode layer on the polished surface.
Step D52: forming a piezoelectric layer on the bottom electrode layer.
Step D53: forming an upper electrode layer on the piezoelectric layer.
Step D6: Etching the sacrificial mesa structure to form holes. However, the hole is located under the bulk acoustic wave resonance structure, in the step D4,
(1) The insulating layer is polished so that the sacrificial mesa structure is not exposed. However, the insulating layer located under the bulk acoustic wave resonance structure, above the pores, and between the polished surface and the upper part of the entire mesa forms a frequency adjustment structure, and the bulk acoustic wave resonance structure The insulating layer located below and between the entire upper surface of the mesa and the holes forms a mass adjustment structure.
Alternatively, (2) the insulating layer is polished so that the sacrificial mesa structure is exposed. However, the insulating layer located under the bulk acoustic wave resonance structure and between the polishing surface and the voids forms a mass adjustment structure.

  In one embodiment, after step D4, the plurality of portions of the sacrificial mesa structure have a geometric configuration. The geometric configuration of the sacrificial mesa structure is related to the geometric configuration of the mass tuning structure, and by adjusting the geometric configuration of the sacrificial mesa structure, a Q factor of the bulk acoustic wave resonator is obtained. Adjust the geometric configuration of the mass adjustment structure to enhance.

  In one embodiment, the substrate is a semiconductor substrate and the sacrificial mesa structure is made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures.

In one embodiment, the substrate is a compound semiconductor substrate, and the step D1 includes the following steps.
Step D11: forming a sacrificial structure on the substrate.
Step D12: Etching the sacrificial structure to form the sacrificial mesa structure.

  In one embodiment, (1) the substrate is made of GaAs and the sacrificial structure is made of a GaAs layer. Alternatively, (2) the substrate is made of InP, and the sacrificial structure is made of an InGaAs layer.

  In certain embodiments, the present application further includes the following steps. A bottom etching stop layer is formed on the substrate, and the sacrificial structure is formed on the bottom etching stop layer. Here, (1) the bottom etching stop layer is made of InGaP. Alternatively, (2) the bottom etching stop layer is made of InP.

Furthermore, the present application provides a method of manufacturing a bulk acoustic wave resonant structure with a mass adjusting structure. The method includes the following steps.
Step E1: A sacrificial mesa structure is formed on a substrate.
Step E2: forming an insulating layer on the sacrificial mesa structure and the substrate.
Step E3: A pre-polished surface is formed by polishing the insulating layer by a chemical mechanical planarization process so that the sacrificial mesa structure is exposed. However, the sacrificial mesa structure is divided into a plurality of parts.
Step E4: Etching the sacrificial mesa structure such that any two adjacent portions of the sacrificial mesa structure have different heights. Here, the uppermost portion of the sacrificial mesa structure has the highest mesa upper surface. The top surface of the highest mesa coincides with the top of the entire mesa.
Step E5: A bulk acoustic wave resonance structure is formed. However, the bulk acoustic wave resonance structure is located above the sacrificial mesa structure, and the step E5 further includes the following steps.
Step E51: forming a second polishing layer on the sacrificial mesa structure and the insulating layer. However, the second polishing layer is made of an insulator.
Step E52: Using a chemical mechanical planarization process, the second polishing layer is polished to the extent that the sacrificial mesa structure is not exposed to form a polished surface.
Step E53: forming a bottom electrode layer on the polished surface.
Step E54: forming a piezoelectric layer on the bottom electrode layer.
Step E55: An upper electrode is formed on the piezoelectric layer.
Step E6: Etching the sacrificial mesa structure to form holes. However, the holes are located below the bulk acoustic wave resonance structure.
The second polishing layer located below the bulk acoustic wave resonance structure, above the vacancies, and between the polishing surface and the upper part of the entire mesa forms a frequency adjustment structure. The second polishing layer located below the bulk acoustic wave resonance structure and between the upper part of the entire mesa and between the holes forms a mass adjustment structure.

  In one embodiment, after step E52, the plurality of portions of the sacrificial mesa structure have a geometric configuration. The geometric configuration of the sacrificial mesa structure is related to the geometric configuration of the mass tuning structure, and by adjusting the geometric configuration of the sacrificial mesa structure, a Q factor of the bulk acoustic wave resonator is obtained. Adjust the geometric configuration of the mass adjustment structure to enhance.

  In one embodiment, the substrate is a semiconductor substrate and the sacrificial mesa structure is made of at least one material selected from the group of metals, alloys, and epitaxial structures.

In one embodiment, the substrate is a compound semiconductor substrate, and the step E1 includes the following steps.
Step E11: forming a sacrificial structure on the substrate.
Step E12: The sacrificial structure is etched to form the sacrificial mesa structure.

  In one embodiment, (1) the substrate is made of GaAs and the sacrificial structure is made of a GaAs layer. Alternatively, (2) the substrate is made of InP, and the sacrificial structure is made of an InGaAs layer.

  In certain embodiments, the present application further includes the following steps. A bottom etching stop layer is formed on the substrate, and the sacrificial structure is formed on the bottom etching stop layer. Here, (1) the bottom etching stop layer is made of InGaP. Alternatively, (2) the bottom etching stop layer is made of InP.

Furthermore, the present application provides a method of manufacturing a bulk acoustic wave resonant structure with a mass adjusting structure. The method includes the following steps.
Step F1: A sacrificial mesa structure is formed on a substrate.
Step F2: forming an insulating layer on the sacrificial mesa structure and the substrate.
Step F3: A pre-polishing layer is formed by polishing the insulating layer by a prior chemical mechanical planarization process so that the sacrificial mesa structure is exposed. However, the sacrificial mesa structure is divided into a plurality of parts.
Step F4: Etch the sacrificial mesa structure so that any two adjacent portions of the sacrificial mesa structure have different heights. Here, the uppermost portion of the sacrificial mesa structure has the highest mesa upper surface. The top surface of the highest mesa coincides with the top of the entire mesa.
Step F5: A bulk acoustic wave resonance structure is formed. However, the bulk acoustic wave resonance structure is located above the sacrificial mesa structure, and the step F5 further includes the following steps.
Step F51: forming a second polishing layer on the sacrificial mesa structure and the insulating layer. However, the second polishing layer is made of at least one material selected from the group consisting of metals and alloys.
Step F52: Using a chemical mechanical planarization process, the second polishing layer is polished to the extent that the sacrificial mesa structure is not exposed to form a polished surface.
Step F53: Patterning the second polishing layer.
Step F54: forming a piezoelectric layer on the polishing surface of the second polishing layer and the preliminary polishing surface of the insulating layer.
Step F55: forming an upper electrode on the piezoelectric layer.
Step F6: Etching the sacrificial mesa structure to form holes. However, the holes are located below the bulk acoustic wave resonance structure.
The second polishing layer located below the piezoelectric layer, above the vacancies, and between the polishing surface and the upper part of the entire mesa forms the bottom electrode layer of the bulk acoustic wave resonance structure. The second polishing layer located below the bulk acoustic wave resonance structure and between the upper part of the entire mesa and between the holes forms a mass adjustment structure.

  In one embodiment, after step F52, the plurality of portions of the sacrificial mesa structure have a geometric configuration. The geometric configuration of the sacrificial mesa structure is related to the geometric configuration of the mass tuning structure, and by adjusting the geometric configuration of the sacrificial mesa structure, a Q factor of the bulk acoustic wave resonator is obtained. Adjust the geometric configuration of the mass adjustment structure to enhance.

  In one embodiment, the substrate is a semiconductor substrate and the sacrificial mesa structure is made of at least one material selected from metals, alloys and epitaxial structures.

In one embodiment, the substrate is a compound semiconductor substrate, and the step F1 includes the following steps.
Step F11: forming a sacrificial structure on the substrate.
Step E12: The sacrificial structure is etched to form the sacrificial mesa structure.

  In one embodiment, (1) the substrate is made of GaAs and the sacrificial structure is made of a GaAs layer. Alternatively, (2) the substrate is made of InP, and the sacrificial structure is made of an InGaAs layer.

  In certain embodiments, the present application further includes the following steps. A bottom etching stop layer is formed on the substrate, and the sacrificial structure is formed on the bottom etching stop layer. Here, (1) the bottom etching stop layer is made of InGaP. Alternatively, (2) the bottom etching stop layer is made of InP.

  Hereinafter, in order to further understand the features and effects of the present application, some preferred embodiments will be described in more detail with reference to the drawings.

FIG. 1A is a cross-sectional view illustrating steps of one embodiment of a method for forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1B is a cross-sectional view illustrating the steps of one embodiment of a method for forming vacancies in the bulk acoustic wave resonator of the present application. FIG. 1C is a cross-sectional view illustrating steps of one embodiment of a method for forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1D is a cross-sectional view illustrating the steps of one embodiment of a method for forming vacancies in the bulk acoustic wave resonator of the present application. FIG. 1E is a cross-sectional view illustrating steps of one embodiment of a method for forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1F is a cross-sectional view illustrating steps of one embodiment of a method for forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1G is a cross-sectional view illustrating steps of another embodiment of a method of forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1H is a cross-sectional view illustrating steps of another embodiment of a method for forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1I is a cross-sectional view showing an epitaxial structure of an embodiment of a method for forming vacancies in the bulk acoustic wave resonator of the present application. FIG. 1J is a cross-sectional view illustrating steps of another embodiment of a method for forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1K is a cross-sectional view illustrating steps of another embodiment of a method for forming a hole in a bulk acoustic wave resonator of the present application. FIG. 1L is a cross-sectional view illustrating an embodiment of a method for forming holes in the bulk acoustic wave resonator of the present application. FIG. 2A is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 2B is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 2C is a cross-sectional view illustrating steps of an embodiment of a frequency adjustment method for a bulk acoustic wave resonator of the bulk acoustic wave filter of the present application. FIG. 2D is a cross-sectional view illustrating the steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 2E is a cross-sectional view illustrating the steps of one embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 2F is a cross-sectional view illustrating steps of an embodiment of a frequency adjustment method for a bulk acoustic wave resonator of the bulk acoustic wave filter of the present application. FIG. 2G is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 2H is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 2I is a cross-sectional view showing two embodiments of the frequency adjustment method for the bulk acoustic wave resonance device of the bulk acoustic wave filter of the present application. FIG. 2J is a cross-sectional view showing two embodiments of the frequency adjustment method for the bulk acoustic wave resonance device of the bulk acoustic wave filter of the present application. FIG. 2K is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 2L is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 2M is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 2N is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3A is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3B is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3C is a cross-sectional view illustrating steps of an embodiment of a frequency adjustment method for a bulk acoustic wave resonator of the bulk acoustic wave filter of the present application. FIG. 3D is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3E is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3F is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of the bulk acoustic wave filter of the present application. FIG. 3G is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonance device of a bulk acoustic wave filter of the present application. FIG. 3H is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3I is a cross-sectional view illustrating steps of another embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3J is a cross-sectional view illustrating steps of another embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3K is a cross-sectional view illustrating steps of another embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 3L is a cross-sectional view showing another embodiment of the frequency adjustment method for the bulk acoustic wave resonance device of the bulk acoustic wave filter of the present application. FIG. 4A is a cross-sectional view illustrating steps of an embodiment of a frequency adjustment method for a bulk acoustic wave resonance device of a bulk acoustic wave filter of the present application. FIG. 4B is a cross-sectional view illustrating steps of an embodiment of a frequency adjustment method for a bulk acoustic wave resonator of the bulk acoustic wave filter of the present application. FIG. 4C is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 4D is a cross-sectional view illustrating steps of one embodiment of a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 4E is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 4F is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 4G is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 4H is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 4I is a cross-sectional view showing another embodiment of the frequency adjustment method for the bulk acoustic wave resonance device of the bulk acoustic wave filter of the present application. FIG. 4J is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 4K is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. FIG. 4L is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 4M is a cross-sectional view illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. FIG. 5 is a cross-sectional view of another embodiment of a method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure of the present application. FIG. 6A is a series of cross-sectional views illustrating an embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6B is a series of cross-sectional views illustrating an embodiment of a method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure of the present application. FIG. 6C is a series of cross-sectional views illustrating an embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6D is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6E is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6F is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6G is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6H is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6I is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjusting structure of the present application. FIG. 6J is a series of cross-sectional views for explaining another embodiment of the method of manufacturing the bulk acoustic wave resonance device with a mass adjusting structure of the present application. FIG. 6K is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6L is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6M is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6N is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6O is a series of cross-sectional views illustrating another embodiment of a method for manufacturing a bulk acoustic wave resonator with a mass adjustment structure of the present application. FIG. 6P is a series of cross-sectional views for explaining another embodiment of the method for manufacturing the bulk acoustic wave resonance device with a mass adjusting structure of the present application. FIG. 6Q is a series of cross-sectional views for explaining another embodiment of the method of manufacturing the bulk acoustic wave resonance device with a mass adjusting structure of the present application. FIG. 6R is a cross-sectional view illustrating an embodiment of a method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure of the present application. FIG. 6S is a top electrode view showing an embodiment of a method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure of the present application. FIG. 7 is a diagram showing an example of a conventional bulk acoustic wave resonance device.

Reference is made to FIGS. 1A to 1F, which are cross-sectional views illustrating the steps of one embodiment of a method for forming vacancies in a bulk acoustic wave resonator of the present application. The method for forming the holes of the bulk acoustic wave resonator of the present application includes the following steps.
Step A1: (See FIG. 1B) A sacrificial epitaxial mesa structure 60 is formed on the compound semiconductor substrate 13. The forming steps are as follows. (See FIG. 1A) A sacrificial epitaxial structure 28 is formed on the compound semiconductor substrate 13. (See FIG. 1B) The sacrificial epitaxial structure 28 is etched to form the sacrificial epitaxial mesa structure 60.
Step A2: (See FIG. 1C) The insulating layer 11 is formed on the sacrificial epitaxial mesa structure 60 and the compound semiconductor substrate 13. However, the insulating layer 11 is made of at least one material selected from the group consisting of silicon nitride (SiNx), silicon oxide (SiO2), and polymer.
Step A3: (See FIG. 1D) The insulating layer 11 is polished using a chemical mechanical polishing process to form a polished surface 41.
Step A4: (See FIG. 1E) The bulk acoustic wave resonance structure 3 is formed on the polishing surface 41. However, the bulk acoustic wave resonance structure 3 is located on the sacrificial epitaxial mesa structure 60.
The step A4 further includes the following steps.
Step A41: The bottom electrode layer 30 is formed on the polishing surface 41. A piezoelectric layer 31 is formed on the bottom electrode layer 30. An upper electrode layer 32 is formed on the piezoelectric layer 31.
Step A5: (See FIG. 1F) The sacrificial epitaxial mesa structure 60 is etched to form vacancies 40. However, the hole 40 is located under the bulk acoustic wave resonance structure 3.
In step A3, the insulating layer 11 is polished to such an extent that the sacrificial epitaxial mesa structure 60 is not exposed (it remains hidden under the insulating layer 11). However, the insulating film 11 between the bottom electrode layer 30 and the sacrificial epitaxial mesa structure 60 forms a frequency adjustment structure 50, the frequency adjustment layer 50 has a constant film thickness T, and the bulk acoustic wave resonance structure 3 is By adjusting the film thickness T of the resonance adjustment structure 50 having the resonance frequency F, the resonance frequency F of the bulk acoustic wave resonance structure 3 can be tuned. As the film thickness T of the frequency adjustment structure 50 increases, the resonance frequency F of the bulk acoustic wave resonance structure 3 decreases. Conversely, as the film thickness T of the frequency adjustment structure 50 decreases, the resonance frequency F of the bulk acoustic wave resonance structure 3 increases. The main feature of the method for forming vacancies in the bulk acoustic wave resonator of the present application is that the sacrificial epitaxial structure 28 is formed as a sacrificial layer using the compound semiconductor substrate 13, and then the insulating layer 11 is polished by a chemical mechanical polishing process. That is. The advantage is that it is easy to accurately adjust the film thickness T of the frequency adjustment structure 50. In addition, the frequency F of the bulk acoustic wave resonance structure 3 is easily tuned accurately. However, if the film thickness T of the frequency adjustment structure 50 is too high, the resonance state of the bulk acoustic wave resonance structure 3 is affected. Therefore, the film thickness T of the frequency adjustment structure 50 is required to be 1000 nanometers or less. In some preferred embodiments, the thickness T of the frequency adjustment structure 50 is 300 nanometers or less.

  Reference is made to FIGS. 1G and 1H, which are cross-sectional views illustrating steps of another embodiment of a method for forming vacancies in a bulk acoustic wave resonator of the present application. The main method of forming the embodiment seen in FIG. 1H is basically the same as the method of forming the embodiment seen in FIG. 1F. However, in step A3, the insulating layer 11 is polished until the sacrificial epitaxial mesa structure 60 is exposed. (See FIG. 1G). Subsequently, the bulk acoustic wave resonance structure 3 is formed on the polished surface 41, and the sacrificial epitaxial mesa structure 60 is etched to form the holes 40. (See FIG. 1H). In this embodiment, the bulk acoustic wave resonance structure 3 does not have the frequency adjustment structure 50 as seen in the embodiment of FIG. 1F.

  Reference is made to FIG. 1I, which is a cross-sectional view illustrating an epitaxial structure of one embodiment of a method for forming vacancies in a bulk acoustic wave resonator of the present application. The main structure of the epitaxial structure of the embodiment of FIG. 1I is basically the same as the embodiment of FIG. 1A. However, the difference is that an etching prevention layer 12 is further formed on the back surface of the compound semiconductor substrate 13. The role of the etching prevention layer 12 protects the back surface of the compound semiconductor substrate 13 and protects the back surface of the compound semiconductor substrate 13 from damage caused by etching (especially etching by an etchant of wet etching) during the etching process during the manufacturing process. That is. The etching prevention layer 12 is made of at least one material selected from the group consisting of silicon nitride (SiNx), silicon oxide (SiO2), aluminum nitride (AlN), and photoresist. A preferred material for the etch stop layer 12 is silicon nitride. Usually, the etching prevention layer 12 is removed after step A5 in order to perform the substrate thinning process. In all other embodiments of the present application, the substrate may be a semiconductor substrate or a compound semiconductor substrate. In order to protect the back surface of the substrate, the etching prevention layer 12 may be formed on the back surface of the semiconductor substrate or may be formed on the back surface of the compound semiconductor substrate.

  Reference is made to FIGS. 1J and 1K, which are cross-sectional views illustrating the steps of another embodiment of the method of forming vacancies in the bulk acoustic wave resonator of the present application. The main structure of the epitaxial structure of the embodiment of FIG. 1J is basically the same as that of the embodiment of FIG. 1A. However, the difference is that a bottom etching stop layer 20 is further formed on the compound semiconductor substrate 13 and a sacrificial epitaxial structure 28 is formed thereon. When the sacrificial epitaxial structure 28 is etched to form the sacrificial epitaxial mesa structure 60, if the sacrificial epitaxial structure 28 around the sacrificial epitaxial mesa structure 60 is etched, the etching stops at the bottom etching stop layer 20. Under the sacrificial epitaxial mesa structure 60, the bottom etching stop layer 20 remains. The bulk acoustic wave resonator embodiment seen in FIG. 1K is formed from the epitaxial structure of the embodiment seen in FIG. 1J. The main structure of the embodiment of FIG. 1K is basically the same as that of the embodiment of FIG. 1F. However, the difference is that the bottom etching stop layer 20 is further formed on the compound semiconductor substrate 13. In step A2, an insulating layer 11 is formed on the sacrificial epitaxial mesa structure 60 and the bottom etch stop layer 20. Therefore, after the sacrificial epitaxial mesa structure 60 is etched in step A5, holes 40 are formed on the bottom etching stop layer 20. In some embodiments, compound semiconductor substrate 13 comprises GaAs, sacrificial epitaxial structure 28 comprises a sacrificial epitaxial layer, and the sacrificial epitaxial layer comprises GaAs. However, the sacrificial epitaxial layer has a constant film thickness between 50 nanometers and 5000 nanometers. The bottom etching stop layer 20 is made of InGaP having a constant film thickness between 20 nanometers and 500 nanometers. In some other embodiments, the compound semiconductor substrate 13 comprises InP, the sacrificial epitaxial structure 28 comprises a sacrificial epitaxial layer, and the sacrificial epitaxial layer comprises InGaAs. However, the sacrificial epitaxial layer has a constant film thickness between 50 nanometers and 5000 nanometers. The bottom etching stop layer 20 is made of InP having a constant film thickness between 20 nanometers and 500 nanometers.

  Reference is made to FIG. 1L, which is a cross-sectional view illustrating one embodiment of a method for forming vacancies in the bulk acoustic wave resonator of the present application. The embodiment of the bulk acoustic wave resonator device seen in FIG. 1L is also formed from the epitaxial structure of the embodiment seen in FIG. 1J. The main structure of the embodiment of FIG. 1L is basically the same as that of the embodiment of FIG. 1K. However, in step A3, the insulating layer 11 is polished so that the sacrificial epitaxial mesa structure 60 is exposed, and then the bulk acoustic wave resonance structure 3 is formed on the polished surface 41, and the sacrificial epitaxial mesa structure 60 is etched to be emptied. The difference is that the hole 40 is formed. (Similar to FIGS. 1G and 1H). Therefore, the bulk acoustic wave resonance structure 3 does not have the frequency adjustment structure 50 as in the embodiment shown in FIG. 1K.

In addition, refer to FIGS. 2A through 2F, which are cross-sectional views illustrating steps of one embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. As shown in FIG. 2F, the structure of this embodiment includes at least one first bulk acoustic wave resonator 1 and at least one second bulk acoustic wave resonator 1 ′ formed on a substrate 10, respectively. Have. In the present embodiment, at least one first bulk acoustic wave resonance device 1 is a series resonance device, and at least one second bulk acoustic wave resonance device 1 ′ is a shunt resonance device. The at least one first bulk acoustic wave resonance device 1 includes at least one first bulk acoustic wave resonance structure 3, a first frequency adjustment structure 50, and at least one first hole 40. The at least one first bulk acoustic wave resonance device 1 ′ includes at least one second bulk acoustic wave resonance structure 3 ′, a second frequency adjustment structure 50 ′, and at least one second hole 40 ′. Is done. The frequency adjustment method for the bulk acoustic wave resonance device of the bulk acoustic wave filter of the present application includes the following steps. Step B1: (See FIG. 2B) A plurality of sacrificial mesas are formed on the substrate 10. However, the plurality of sacrificial mesas are composed of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′. Here, the height of at least one first sacrificial mesa structure 6 is larger than the height of at least one second sacrificial mesa structure 6 ′, and both have a first height difference HD1. In the present embodiment, the substrate 10 is a semiconductor substrate. The plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys and epitaxial structures. Step B2: (See FIG. 2C) An insulating layer 11 is formed on the sacrificial mesa structure and the substrate 10. However, the insulating layer 11 is made of at least one material selected from the group consisting of silicon nitride (SiNx), silicon oxide (SiO2) and polymer. Step B3: (see FIG. 2D) The insulating layer 11 is polished by a chemical mechanical polishing process to form a polished surface 41.
Step B4: (see FIG. 2E) A plurality of bulk acoustic wave resonance structures are formed on the polishing surface 41. (In all embodiments of the bulk acoustic wave filter of the present application, the plurality of bulk acoustic wave resonance structures are all formed on the extended surface 43. In this embodiment, the extended surface 43 is the same as the polished surface 41.) The plurality of bulk acoustic wave resonance structures include at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′. The at least one first bulk acoustic wave resonant structure 3 and the at least one second bulk acoustic wave resonant structure 3 'are respectively at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa. Located on top of structure 6 '.
Step B4 includes the following steps.
Step B41: The bottom electrode layer 30 is formed on the polishing surface 41.
Step B42: The piezoelectric layer 31 is formed on the bottom electrode layer 30.
Step B43: The upper electrode layer 32 is formed on the piezoelectric layer 31.
Step B5: (See FIG. 2F) A plurality of sacrificial mesas are etched to form a plurality of vacancies. However, the plurality of holes are respectively located under the plurality of bulk acoustic wave resonance structures. The plurality of holes includes at least one first hole 40 and at least one second hole 40 ′. These at least one first hole 40 and at least one second hole 40 'are respectively the at least one first acoustic wave resonance structure 3 and the at least one first acoustic wave resonance structure 3'. Located below.
In step B3, the insulating layer 11 is polished to such an extent that the at least one first sacrificial mesa structure 6 and the at least one first sacrificial mesa structure 6 ′ are not exposed (hidden under the insulating layer 11). Thus, under the polishing surface 41, the insulating layers 11 located under the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ each have at least one A first frequency adjustment structure 50 of the first bulk acoustic wave resonance structure 3 and a second frequency adjustment structure 50 ′ of at least one second bulk acoustic wave resonance structure 3 ′ are formed. However, the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ have a first film thickness difference TD1, which is equal to the first height difference HD1. The first resonance frequency F 1 of at least one first bulk acoustic wave resonance structure 3 is tuned by the first frequency adjustment structure 50. On the other hand, the second resonance frequency F2 of at least one second bulk acoustic wave resonance structure 3 ′ is tuned by the second frequency adjustment structure 50 ′. Since the film thickness of the second frequency adjustment structure 50 ′ is larger than the film thickness of the first frequency adjustment structure 50, the second resonance frequency F2 of the at least one second acoustic wave resonance structure 3 ′ is at least one. The first acoustic wave resonance structure 3 is tuned so as to be lower than the first resonance frequency F1. Therefore, at least one first acoustic wave resonance structure 3 and at least one second acoustic wave resonance structure 3 ′ have a first resonance frequency difference FD1. However, this FD1 correlates with the first film thickness difference TD1 of the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′. That is, the first resonance frequency difference FD1 correlates with the first height difference HD1 of at least one first sacrificial mesa structure 6 and at least one first sacrificial mesa structure 6 ′. Thus, by adjusting the first height difference HD1, the first resonance frequency difference FD1 between the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ is set. It becomes possible to adjust. Since the size of the substrate 10 is much larger than the size of the bulk acoustic wave resonator, when the insulating layer 11 is polished in the chemical mechanical polishing process, the polishing depth of the insulating layer 11 near the center of the substrate 10 is usually from the center of the substrate 10. It is not the same as the polishing depth of the insulating layer 11 at a remote location. However, the polishing depth of the insulating film 11 should be substantially the same in adjacent bulk acoustic wave resonators, particularly a plurality of bulk acoustic wave resonators having the same bulk acoustic wave filter. One of the features of the present application is that the first film thickness difference TD1 between the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ of the same bulk acoustic wave filter is separated from the vicinity of the center of the substrate 10 and from the center. It will not change in different places. That is, the first resonance frequency difference FD1 of at least one first acoustic wave resonance structure 3 and at least one second acoustic wave resonance structure 3 ′ of the same bulk acoustic wave filter is the vicinity of the center of the substrate 10 and the center. It doesn't change in the place away from In the same bulk acoustic wave filter, the first resonance frequency difference FD1 of at least one first acoustic wave resonance structure 3 and at least one second acoustic wave resonance structure 3 ′ is at least one first frequency adjustment structure. 50 and the first film thickness difference TD1 of at least one second frequency tuning structure 50 ′, and the first of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′. And the material of the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′. At least one first bulk acoustic wave resonance structure by adjusting the first height difference HD1 or by selecting different types of materials for the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′. 3 and at least one second bulk acoustic wave resonant structure 3 ′ can be adjusted for the first resonant frequency difference FD1. Further, in the present application, the first resonance frequency difference FD1 between the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ is separated from the center of the substrate 10 and away from the center. It doesn't change in place. This is one of the main features of the present application and greatly assists in the subsequent trimming process. If the same bulk acoustic wave filter is used in any region on the wafer, the first resonant frequency difference FD1 of at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ' Is controlled accurately and is location independent, thus significantly reducing the time cost of the trimming process. In some embodiments, the substrate 10 comprises a compound semiconductor substrate. The plurality of sacrificial mesas are made of an epitaxial structure.
Step B1 consists of the following steps.
Step B11: (See FIG. 2A) A sacrificial structure 21 is formed on the substrate 10.
Step B12: The sacrificial structure 21 is etched to form a plurality of sacrificial mesas. However, the plurality of sacrificial metastructures are composed of at least one first sacrificial mesa structure 6 (21) and at least one second sacrificial mesa structure 6 ′ (21). Here, the plurality of sacrifice mesa structures have the same height.
Step B13: (See FIG. 2B) At least one first sacrificial mesa such that at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. Etch structure 6 and at least one second sacrificial mesa structure 6 ', or etch at least one second sacrificial mesa structure 6'.

  Reference is made to FIGS. 2G and 2H, which are cross-sectional views illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the present embodiment, the substrate 10 is a semiconductor substrate, and the plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures. The main steps forming the embodiment found in FIG. 2H are basically the same as the steps forming the embodiment found in FIG. 2F. However, in step B3, at least one first sacrificial mesa structure 6 is exposed and at least one second sacrificial mesa structure 6 ′ is not exposed (hidden under the insulating layer 11). Layer 11 is polished. (See FIG. 2G) Therefore, under the polishing surface 41 (expansion surface 43), the insulating layer 11 located under the at least one second bulk acoustic wave resonance structure 3 ′ has at least one second bulk. A second frequency adjustment structure 50 ′ of the acoustic wave resonance structure 3 ′ is formed. As seen in FIG. 2H, the second frequency adjustment structure 50 'has a film thickness T2, which is the same as the first height difference HD1. In this embodiment, there is no first frequency adjustment structure 50 as seen in the embodiment of FIG. 2F. Therefore, the first resonance frequency difference FD1 of the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ is the film thickness of the second frequency adjustment structure 50 ′. Correlate with T2. That is, the first resonance frequency difference FD1 correlates with the first height difference HD1 of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 '. Thus, by adjusting the first height difference HD1, the first resonance frequency difference FD1 of at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′ is obtained. It becomes possible to adjust.

  Reference is made to FIG. 2I, which is a cross-sectional view illustrating another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. The main structure of the embodiment of FIG. 2I is basically the same as that of the embodiment of FIG. 2F. However, the difference is that a bottom etching stop layer 20 is further formed on the substrate 10 and an insulating layer 11 is formed thereon. At least one first hole 40 and at least one second hole 40 ′ are located on the bottom etch stop layer 20. The main method of forming the embodiment found in FIG. 2I is basically the same as that of the method of forming the embodiment found in FIG. 2F. However, the difference is that the following step is further included before step B11. A bottom etching stop layer 20 is formed on the substrate 10. However, in step B11, the sacrificial structure 21 is formed thereon. In step B 2, the insulating layer 11 is formed on the plurality of sacrificial mesa structures and the bottom etching stop layer 20. In the present embodiment, the substrate 10 is a compound semiconductor substrate, and the plurality of sacrificial mesas (sacrificial structures 21) are epitaxial structures. In some embodiments, the substrate 10 is GaAs and the sacrificial structure 21 comprises a sacrificial epitaxial layer. However, the sacrificial epitaxial structure 21 is made of GaAs, and the sacrificial epitaxial layer has a constant film thickness between 50 nanometers and 5000 nanometers. The bottom etching stop layer 20 is made of InGaP. Here, the bottom etching stop layer 20 has a constant film thickness of 20 nanometers to 500 nanometers. In some other embodiments, the substrate 10 is InP and the sacrificial structure 21 comprises a sacrificial epitaxial layer. However, the sacrificial epitaxial layer is made of InGaAs and has a constant film thickness between 50 nanometers and 5000 nanometers. The bottom etching stop layer 20 is made of InP. However, the bottom etch stop layer 20 has a constant thickness between 20 nanometers and 500 nanometers.

  Reference is made to FIG. 2J, which is a cross-sectional view illustrating another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. The substrate 10 is a compound semiconductor substrate, and the plurality of sacrificial mesas are epitaxial structures. The main structure of the embodiment of FIG. 2J is basically the same as that of the embodiment of FIG. 2I. However, in step B3, at least one first sacrificial mesa structure 6 is exposed (as in FIG. 2G), and at least one second sacrificial mesa structure 6 ′ is not exposed (of the insulating layer 11). The insulating layer 11 is polished to such an extent that it is hidden underneath. Thus, the insulating layer 11 positioned below the at least one second bulk acoustic wave resonance structure 3 ′ under the polishing surface 41 (expansion surface 43) becomes at least one second bulk acoustic wave resonance structure 3 ′. The second frequency adjustment structure 50 ′ is formed.

  Reference is made to FIGS. 2K to 2N, which are cross-sectional views illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the embodiment of FIG. 2K, the substrate 10 is a compound semiconductor substrate and the sacrificial structure 21 comprises an epitaxial layer. The main structure of the epitaxial structure of the embodiment of FIG. 2K is basically the same as that of the embodiment of FIG. 2A. However, the sacrificial structure 21 is composed of the epitaxial layer 27, the first etching stop layer 22, and the first fine adjustment layer 23, and the sacrificial epitaxial layer 27 is formed on the substrate 10, and the first etching is performed thereon. A stop layer 22 is formed, and a first fine adjustment layer 23 is further formed thereon. As seen in FIG. 2L, the sacrificial structure 21 is etched to form a plurality of sacrificial mesas. However, the plurality of sacrificial mesas are composed of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 '. However, the plurality of sacrifice mesa structures have the same height (step B12). As seen in FIG. 2M, the first fine adjustment layer 23 has a film thickness FT1. The fine-tuning layer 23 of at least one second sacrificial mesa structure 6 ′ so that at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. Is etched (step B13). FIG. 2N shows the results after step B2, step B3 and step B4. The result after etching (step B5) at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 'of FIG. 2N is identical to the embodiment of FIG. 2F. This serves to accurately tune the first resonant frequency difference FD1 of at least one first bulk acoustic wave resonator 3 and at least one second bulk acoustic wave resonator 3 '. In some embodiments, the substrate 10 is GaAs, the sacrificial epitaxial layer 27 is GaAs, and the first etch stop layer 22 is made of AlAs or InGaP and is a constant film between 1 nanometer and 50 nanometers. Have a thickness. The first fine adjustment layer 23 is made of GaAs, and its film thickness FT1 is between 1 nanometer and 300 nanometers. In some other embodiments, the substrate 10 is comprised of InP, the sacrificial epitaxial layer 27 is comprised of InGaAs, and the first etch stop layer 22 is comprised of InP, and a constant film between 1 nanometer and 50 nanometers. Have a thickness. The first fine adjustment layer 23 is made of InGaAs, and its film thickness FT1 is between 1 nanometer and 300 nanometers.

Reference is made to FIGS. 3A to 3G, which are cross-sectional views illustrating steps of one embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. Using the frequency adjustment method for a bulk acoustic wave resonator of the bulk acoustic wave filter of the present application, at least one first bulk acoustic wave resonator 1 and at least one second bulk acoustic wave resonator 1 ′ (FIG. To form 3G), there are the following steps:
Step C1: Form a plurality of sacrificial mesas on the substrate 10. However, the plurality of sacrificial mesas have the same height and are composed of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′. In this embodiment, the substrate 10 is a semiconductor substrate, and the plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures.
Step C2: (See FIG. 3A) An insulating layer 11 is formed on the plurality of sacrificial mesas and the substrate.
Step C3: (FIG. 3B) The pretreatment polishing surface 42 is formed by polishing the substrate 11 in the pretreatment chemical mechanical polishing step so that the plurality of sacrificial mesas are exposed.
Step C4: (See FIG. 3C) At least one second sacrificial mesa such that at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. Etch structure 6 '. However, the height of at least one first sacrificial mesa structure 6 is greater than the height of at least one second sacrificial mesa structure 6 ′.
Step C5: (See FIGS. 3D to 3F) A plurality of bulk acoustic wave resonance structures are formed. However, the plurality of bulk acoustic wave resonance structures include at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′. The at least one first bulk acoustic wave resonant structure 3 and the at least one second bulk acoustic wave resonant structure 3 'are respectively at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure. Located on 6 '.
Step C5 includes the following steps.
Step C51: A second polishing layer 51 is formed on the plurality of sacrificial mesas and the insulating layer 11. However, the second polishing layer 51 is made of an insulator, and the insulator is made of a group consisting of silicon nitride (SiNx), silicon oxide (SiO2), aluminum nitride, and zinc oxide (ZnO). At least one material selected.
Step 52: In a chemical mechanical polishing process, at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ are not exposed (hidden under the second polishing layer 51). The second polishing layer 51 is polished to form the polishing surface 41. Thus, under the polishing surface 41, the second polishing layer 51, which is located under the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′, respectively, A first frequency adjustment structure 50 of one first bulk acoustic wave resonance structure 3 and a first frequency adjustment structure 50 ′ of at least one second bulk acoustic wave resonance structure 3 ′ are formed. However, the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ have a first film thickness difference TD1, which is equal to the first height difference HD1.
Step C53: The bottom electrode layer 30 is formed on the polishing surface 41. (As described above, a plurality of bulk acoustic wave resonance structures are formed on the extended surface 43. In this embodiment, the extended surface 43 is the same as the polished surface 41.)
Step C54: The piezoelectric layer 31 is formed on the bottom electrode layer 30.
Step C55: The upper electrode 32 is formed on the piezoelectric layer 31.
Step C6: (See FIG. 3G) Etch a plurality of sacrificial mesas to form a plurality of vacancies. However, each of these holes is located under a plurality of bulk acoustic wave resonators. The plurality of holes are composed of at least one first hole 40 and at least one second hole 40 ′. At least one first bulk acoustic wave resonator 3 and at least one second bulk acoustic wave resonator 3 ′ have a first resonant frequency FD1, which is the first resonant frequency adjustment structure 50 and This is correlated with the first film thickness difference TD1 of the second resonance frequency adjusting structure 50 ′. That is, the first resonance frequency difference FD1 correlates with the first height difference HD1.
In this way, by adjusting the first height difference HD1, the first resonance frequency difference FD1 of at least one first bulk acoustic wave resonator 3 and at least one second bulk acoustic wave resonator 3 ′ is obtained. It becomes possible to tune. In some embodiments, the substrate 10 is a compound semiconductor and the plurality of sacrificial mesas are composed of epitaxial structures. Here, step C1 comprises the following steps.
Step C11: A sacrificial structure 21 is formed on the substrate 10.
Step C12: The sacrificial structure 21 is etched to form a plurality of sacrificial mesas. However, these multiple sacrificial mesas have the same height.

  Reference is made to FIGS. 3H and 3I, which are cross-sectional views illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the present embodiment, the substrate 10 is a semiconductor substrate, and the plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures. The main steps for forming the embodiment found in FIG. 3I are basically the same as those for forming the embodiment found in FIG. 3G. However, in step C52, at least one first sacrificial mesa structure 6 is exposed and at least one second sacrificial mesa structure 6 ′ is not exposed (hidden under the second polishing layer 51). The second polishing layer 51 is polished. (See FIG. 3H) Thus, under the polishing surface 41 (expansion surface 43), the second polishing layer 51 located under the at least one second bulk acoustic wave resonance structure 3 ′ has at least one first A second frequency adjustment structure 50 'of the second bulk acoustic wave resonance structure 3' is formed. However, the second frequency adjustment structure 50 'has a film thickness T2. This T2 is equal to the first height difference HD1. In this embodiment, there is no first frequency adjustment structure 50 as seen in the embodiment of FIG. 3G. Therefore, the first resonance frequency difference FD1 of the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ is the film thickness of the second frequency adjustment structure 50 ′. Correlates with T2. That is, the first resonance frequency difference FD1 correlates with the first height difference HD1 of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 '. Thus, by adjusting the first height difference HD1, the first resonance frequency difference FD1 of at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′ is tuned. It becomes possible to do. In the present embodiment, the second polishing layer 51 is made of at least one material selected from the group consisting of metals, alloys and insulators.

Reference is made to FIGS. 3J and 3K, which are cross-sectional views illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the present embodiment, the substrate 10 is a semiconductor substrate, and the plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures. The main steps for forming the embodiment found in FIG. 3K are basically the same as those for forming the embodiment found in FIG. 3G. However, in step C5, a plurality of bulk acoustic wave resonance structures are formed on the extended surface 43, and the extended surface 43 is the same as the pretreated polishing surface 42. Here, step C5 includes the following steps.
Step C51 ′: (see FIG. 3D) The second polishing layer 51 is formed on the plurality of sacrificial mesas and the insulating layer 11. However, the second polishing layer 51 is made of at least one material selected from the group consisting of metals and alloys. In a preferred embodiment, the second polishing layer 51 is made of at least one material selected from the group consisting of Ru, Ti, Mo, Pt, Au, Al, and W.
Step C52 ′: (see FIG. 3E) The second polishing layer 51 is polished by a chemical mechanical polishing step so that the plurality of sacrificial mesas are not exposed (hidden under the second polishing layer 51).
Step C53 ′: (see FIG. 3J) The second polishing layer 51 is patterned.
Step C54 ′: The piezoelectric layer 31 is formed on the polished surface 41.
Step C55 ′: The upper electrode layer 32 is formed on the piezoelectric layer 31. After step C6 of etching a plurality of sacrificial mesas, the embodiment of FIG. 3K is formed. In step C4, at least one second sacrificial mesa structure 6 'is etched. However, the second polishing layer 51 on the pretreatment polishing surface 42 (expansion surface 43) located under the polishing surface 41 and under the at least one first bulk acoustic wave resonance structure 3 has at least one The bottom electrode layer 30 of the first bulk acoustic wave resonance structure 3 is formed. Here, the second polishing layer 51 on the pretreatment polishing surface 42 (expansion surface 43) located under the polishing surface 41 and below the at least one second bulk acoustic wave resonance structure 3 ′ has at least The bottom electrode layer 30 of one second bulk acoustic wave resonance structure 3 ′ is formed. Under the pretreatment polishing surface 42 (expansion surface 43), the second polishing layer 51 located under the at least one second bulk acoustic wave resonance structure 3 ′ has at least one second bulk acoustic wave resonance. A second frequency tuning structure 50 'of structure 3' is formed. However, the second frequency adjustment structure 50 ′ has a film thickness T2, and the film thickness T2 of the second frequency adjustment structure 50 ′ is equal to the first height difference HD1.
Thus, by adjusting the first height difference HD1, the first resonance frequency difference FD1 between the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ is obtained. It becomes possible to tune.

Reference is made to FIG. 3L, which is a cross-sectional view illustrating another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the present application, the substrate 10 is a semiconductor substrate. The plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys and epitaxial structures. The main steps for forming the embodiment found in FIG. 3L are basically the same as those for forming the embodiment found in FIG. 3G. However, the difference is that step C5 comprises the following steps.
Step C51 ″: (see FIG. 3D) The second polishing layer 51 is formed on the plurality of sacrificial mesas and the insulating layer 11. However, the second polishing layer 51 is made of at least one material selected from the group consisting of metals, alloys, and insulating films.
Step C52 ″: (see FIG. 3E) At least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ are not exposed (hidden under the second polishing layer 51) In addition, the second polishing layer 51 is polished in a chemical mechanical polishing step to form the polishing surface 41.
Step C53 ″: (see FIG. 3J) The second polishing layer 51 is patterned.
Step C54 ″: The bottom electrode layer 30 is formed on the polishing surface 41 (extended surface 43).
Step C55 ″: The piezoelectric layer 31 is formed on the bottom electrode layer 30.
Step C56 ″: The upper electrode layer 32 is formed on the piezoelectric layer 31. The embodiment of FIG. 3L is formed after step C6.
Thus, under the polishing layer 41, the second polishing layer 51, which is located under the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′, respectively, The first frequency adjustment structure 50 of at least one first bulk acoustic wave resonance structure 3 and the second frequency adjustment structure 50 ′ of at least one second bulk acoustic wave resonance structure 3 ′ are formed. However, the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ have a first film thickness difference TD1, which is equal to the first height difference HD1. Thus, by adjusting the first height difference HD1, the first resonance frequency difference FD1 between the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ is set. It becomes possible to tune.

  In the embodiment of FIGS. 3G and 3I, in step C2 (see FIG. 3A), a very thick insulating layer 11 is first formed. Here, the film thickness of the insulating layer 11 must be higher than the height of the plurality of sacrificial mesas. In step C3 (see FIG. 3B), the chemical mechanical polishing step must polish the insulating layer 11 so that the thickness of the insulating layer 11 after polishing is at least equal to or higher than the height of the plurality of sacrificial mesas. Don't be. However, the chemical mechanical polishing process also has drawbacks. That is, if the required polishing depth is too deep, the uniformity of the polishing surface is impaired. In the present embodiment, since the required polishing depth of the insulating layer 11 is very deep, the uniformity of the pretreated polishing surface 42 is impaired after polishing. However, the required polishing depth of the second polishing layer 51 formed in the later step C51 is very thin compared to the required polishing depth of the insulating layer 11. The polishing depth of the second polishing layer 51 simply needs to be thicker than the first height difference HD1. Therefore, the uniformity of the polishing surface 41 formed after polishing the second polishing layer 51 in the chemical mechanical polishing step of Step C52 is not impaired. Here, forming the bottom electrode layer 30 of the at least one first bulk acoustic wave resonator 1 and the at least one second bulk acoustic wave resonator 1 ′ on the polishing surface 41 includes at least one This is useful for improving the resonance characteristics of the first bulk acoustic wave resonator 1 and the at least one second bulk acoustic wave resonator 1 ′. This situation is the same in the embodiment of FIG. 3L. Even in the embodiment of FIG. 3K, the piezoelectric layers of at least one first bulk acoustic wave resonator 1 and at least one second bulk acoustic wave resonator 1 ′ may be formed on the polishing surface 41, This is useful for improving the resonance characteristics of one first bulk acoustic wave resonator 1 and at least one second bulk acoustic wave resonator 1 ′.

  The embodiments of FIGS. 3G, 3I, 3K, and 3L are formed from a sacrificial structure similar to that of FIG. 2K. However, the substrate 10 is a compound semiconductor. Here, the sacrificial structure 21 includes a sacrificial epitaxial layer 27, a first etching stop layer 22, and a first fine adjustment layer 23. However, the sacrificial epitaxial layer 27 is formed on the substrate 10. The first etching stop layer 22 is formed on the sacrificial epitaxial layer 27. The first fine adjustment layer 23 is formed on the first etching stop layer 22. However, the first fine adjustment layer 23 has a film thickness FT1. In step C4, at least one second sacrificial mesa structure 6 ′ and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. The fine adjustment layer 23 is etched. Thus, the first height difference HD1 is determined by the film thickness FT1 of the first fine adjustment layer 23. Therefore, it is possible to accurately adjust the first height difference HD1. It is also possible to accurately tune the first resonance frequency difference FD1 between at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 '.

  Reference is made to FIGS. 4A to 4D, which are cross-sectional views illustrating steps of one embodiment of a frequency tuning method for a bulk acoustic wave resonator of the present bulk acoustic wave filter. The main steps for forming the embodiment seen in FIG. 4D are basically the same as those for forming the embodiment seen in FIG. 3G. However, in step C4 (see FIG. 4A), at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. The sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 '. However, the height of at least one first sacrificial mesa structure 6 is greater than the height of at least one second sacrificial mesa structure 6 '. The embodiment of FIG. 4D is formed after step C51 (see FIG. 4B), step C52 (FIG. 4C), step C53 to step C55 and step C6. However, the second polishing layer 51 is made of an insulator. In the present embodiment, the substrate 10 is a semiconductor substrate. The plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys and epitaxial structures.

  Reference is made to FIGS. 4E and 4F, which are cross-sectional views illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the present embodiment, the substrate 10 is a semiconductor substrate, and the plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures. The main steps for forming the embodiment seen in FIG. 4F are basically the same as those for forming the embodiment seen in FIG. 4D. However, in step C52 (see also FIG. 4E), the polishing surface 41 (expansion surface 43) is the same as the pretreatment polishing surface 42, or the polishing surface 41 is lower than the pretreatment polishing surface 42. The second polishing layer 51 is polished. However, at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ are not exposed (hidden under the second polishing layer 51). In the embodiment of FIG. 4F, the second polishing layer 51 is made of at least one material selected from the group consisting of metals, alloys, and insulators.

  Reference is made to FIGS. 4G and 4H, which are cross-sectional views illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the present embodiment, the substrate 10 is a semiconductor substrate. The plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys and epitaxial structures. The main steps for forming the embodiment found in FIG. 4H are basically the same as those for forming the embodiment found in FIG. 3K. However, in step C4 (see FIG. 4A), at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. The sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 '. Here, the height of at least one first sacrificial mesa structure 6 is greater than the height of at least one second sacrificial mesa structure 6 '. In Step C5, a plurality of bulk acoustic wave resonance structures are formed on the extended surface 43. However, the extended surface 43 is the same as the pretreated polishing surface 42. After step C53 ′ (see FIG. 4G), step C54 ′, step C55 ′, and step C6 (see FIG. 4H) of patterning the second polishing layer 51, at least one first under the polishing surface 41 The second polishing layer 51 located below the bulk acoustic wave resonance structure 3 and above the pretreated polishing surface 42 (expansion surface 43) is a bottom electrode layer 30 of at least one first bulk acoustic wave resonance structure 3. Form. However, the second polishing layer 51 positioned under the at least one first bulk acoustic wave resonance structure 3 under the pretreatment polishing surface 42 (expansion surface 43) has at least one first bulk acoustic wave. A first frequency adjustment structure 50 of the resonance structure 3 is formed. Below the polishing surface 41, the second polishing layer 51 located below the at least one second bulk acoustic wave resonant structure 3 ′ and above the pretreated polishing surface 42 (expansion surface 43) has at least one The bottom electrode layer 30 of the second bulk acoustic wave resonance structure 3 ′ is formed. Under the pretreatment polishing surface 42 (expansion surface 43), the second polishing layer 51 located under the at least one second bulk acoustic wave resonance structure 3 ′ has at least one second bulk acoustic wave resonance. A second frequency tuning structure 50 'of structure 3' is formed. The first frequency adjustment structure 50 and the second frequency adjustment structure 50 'have a first film thickness difference TD1, which is equal to the first height difference HD1. Thus, by adjusting the first height difference HD1, the first resonance frequency difference FD1 between the at least one first bulk acoustic wave resonance structure 3 and the at least one second bulk acoustic wave resonance structure 3 ′ is obtained. It becomes possible to tune. The second polishing layer 51 is made of at least one material selected from the group consisting of metals and alloys. However, in a preferred embodiment, the second polishing layer 51 is made of at least one material selected from the group consisting of Ru, Ti, Mo, Pt, Au, Al, and W.

  Reference is made to FIG. 4I, which is a cross-sectional view illustrating another embodiment of a frequency adjustment method for a bulk acoustic wave resonance device of a bulk acoustic wave filter of the present application. In the present embodiment, the substrate 10 is a semiconductor substrate, and the plurality of sacrificial mesas are made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures. The main steps for forming the embodiment found in FIG. 4I are basically the same as those for forming the embodiment found in FIG. 3L. However, in step C4 (see FIG. 4A), at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. The difference is that both the sacrificial mesa structure 6 and the at least one second sacrificial mesa structure 6 'are etched. However, the height of at least one first sacrificial mesa structure 6 is greater than the height of at least one second sacrificial mesa structure 6 '. In step 52 '', the second sacrificial mesa structure 6 and the at least one second sacrificial mesa structure 6 'are not exposed (hidden under the second polishing layer 51). The polishing layer 51 is polished. After step 53 ″ (see FIG. 4G), step C54 ″ to step C56 ″ and step C6 (see FIG. 4I) for patterning the second polishing layer 51, the polishing surface 41 (extended surface 43) Underneath, at least one first bulk acoustic wave resonant structure 3 and at least one second bulk acoustic wave resonant structure 3 ′, each of the second polishing layer 51 is at least one first bulk acoustic wave resonant structure 3 ′. The first frequency adjustment structure 50 of the bulk acoustic wave resonance structure 3 and the second frequency adjustment structure 50 ′ of the at least one second bulk acoustic wave resonance structure 3 ′ are formed. The first frequency adjustment structure 50 and the second frequency adjustment structure 50 'have a first film thickness difference TD1, which is equal to the first height difference HD1. Thus, by adjusting the first height difference HD1, the first resonance frequency difference FD1 of at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′ is obtained. It becomes possible to tune. In the present embodiment, the second polishing layer 51 is made of at least one material selected from the group consisting of metals, alloys and insulators.

Reference is made to FIGS. 4J to 4M, which are cross-sectional views illustrating steps of another embodiment of a frequency tuning method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. In the embodiment of FIG. 4J, the substrate 10 is a compound semiconductor substrate and the sacrificial structure 21 comprises an epitaxial structure. The main structure of the epitaxial structure of the embodiment of FIG. 4J is basically the same as that of the embodiment of FIG. 2L. However, the sacrificial structure 21 is different in that it is composed of a sacrificial epitaxial layer 27, a first etching stop layer 22, a first fine adjustment layer 23, and an upper etching stop layer 26. Here, step C1 comprises the following steps.
Step C11: A sacrificial structure 21 is formed on the substrate 10.
Step C12: The sacrificial structure 21 is etched to form a plurality of sacrificial mesas. However, the plurality of sacrificial mesas have the same height, and the plurality of sacrificial mesas are composed of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′. . However, a sacrificial epitaxial layer 27 is formed on the substrate 10, a first etching stop layer 22 is formed thereon, a first fine adjustment layer 23 is formed thereon, and an upper etching stop layer 26 is formed thereon. Is formed.
The structure of the embodiment of FIG. 4K is formed after steps C2 and C3. Step 4 consists of the following steps.
Step C41: (See FIG. 4L) The upper etching stop layer 26 of at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ is etched.
Step C42: (See FIG. 4M) At least one second sacrificial mesa such that at least one first sacrificial mesa structure 6 and at least one second sacrificial mesa structure 6 ′ have a first elevation difference HD1. The first fine adjustment layer 23 of the structure 6 ′ is etched.
The first fine adjustment layer 23 has a film thickness FT1, and therefore the first height difference HD1 is determined by the film thickness FT1 of the first fine adjustment layer 23. In this way, the first height difference HD1 can be accurately adjusted. Here, the first film thickness difference TD1 between the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ can be accurately adjusted. In addition, the first resonance frequency difference FD1 of at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′ can be accurately tuned. The embodiments of FIGS. 4D, 4F, 4H, and 4I are formed from the structure of FIG. 4M. In order to form the embodiments of FIGS. 4D, 4F, 4H, and 4I from the epitaxial structure of FIG. 4M, in step C3, the insulating layer 11 is polished so that a plurality of sacrificial mesas are exposed. However, during polishing, it is impossible to polish and simultaneously expose a plurality of sacrificial mesas structures located near the center of the substrate 10 and a plurality of sacrificial mesas structures located away from the center of the substrate 10. is there. For example, suppose a plurality of sacrificial mesas that are located far from the center of the substrate 10 are exposed first. At this time, the polishing must still be continued in order to expose a plurality of sacrificial mesas located near the center of the substrate 10. Therefore, the plurality of sacrificial mesas that are located away from the center of the substrate 10 are excessively polished. Thus, after polishing, the film thickness of the first fine adjustment layer 23 of the plurality of sacrificial mesas located far from the center of the substrate 10 is the first film thickness of the plurality of sacrificial mesas located in the center of the substrate 10. The thickness of the fine adjustment layer 23 becomes smaller. A plurality of sacrificial mesa structure first fine tuning layers 23 located near the center of the substrate 10 have a thickness that is far from the center of the substrate 10. In order to avoid becoming equal to the film thickness of the substrate 23, the film thickness of the first fine adjustment layer 23 of the plurality of sacrificial mesa structures located near the center of the substrate 10 is located away from the center of the substrate 10. The upper etching stop layer 26 is introduced so that it can be set equal to the film thickness of the first fine adjustment layer 23 having a plurality of sacrificial mesas. In some embodiments, the substrate 10 is made of GaAs. The sacrificial epitaxial layer 27 is made of GaAs. The first etching stop layer 22 is made of AlAs or InGaP. However, the film thickness of the first etching stop layer 22 is between 1 nanometer and 50 nanometers. The first fine adjustment layer 23 is made of GaAs. However, the film thickness FT1 of the first fine adjustment layer 23 is between 1 nanometer and 300 nanometers. The upper etching stop layer 26 is made of InGaP. However, the film thickness of the upper etching stop layer 26 is between 50 nanometers and 300 nanometers. In some other embodiments, the substrate 10 is made of InP. The sacrificial epitaxial layer 27 is made of InGaAs. The first etching stop layer 22 is made of InP. However, the film thickness of the first etching stop layer 22 is between 1 nanometer and 50 nanometers. The first fine adjustment layer 23 is InGaAs. However, the film thickness FT1 of the first fine adjustment layer 23 is between 1 nanometer and 300 nanometers. The upper etching stop layer 26 is made of InP. However, the film thickness of the upper etching stop layer 26 is between 50 nanometers and 300 nanometers.

  All embodiments of FIGS. 2F, 2H, 2I, 2J, 3G, 3I, 3K, 3L, 4D, 4F, 4H, and 4I have common characteristics. At least one first bulk acoustic wave resonator 1 and at least one second bulk acoustic wave resonator 1 ′ are formed by a frequency adjustment method for a bulk acoustic wave resonator of a bulk acoustic wave filter of the present application. . The common characteristic is that the bottom electrode layer 30 of any bulk acoustic wave resonance structure (at least one first bulk acoustic wave resonance structure 3 or at least one second bulk acoustic wave resonance structure 3 ′) 43 is formed on the top. The common structure of these embodiments includes an insulating layer 11 having a plurality of holes and formed on the substrate 10, and a plurality of bulk acoustic wave resonance structures respectively positioned on the plurality of holes. The plurality of bulk acoustic wave resonance structures includes at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′, and the plurality of holes include at least one The first air hole 40 and at least one second air hole 40 'are composed of at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3'. Located on the at least one first hole 40 and the at least one second hole 40 '. However, at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 'have a first resonance frequency difference FD1. Each of the plurality of bulk acoustic wave resonance structures includes a bottom electrode layer 30 formed on the extended surface 43, a piezoelectric layer 31 formed thereon, a top electrode layer 32 formed thereon, and a frequency. The structure to adjust. The differences between these embodiments are as follows. (1) In the embodiments of FIGS. 2H, 2J, 3I, and 3K, the structure for adjusting the frequency has the surface on which the insulating layer 11 is polished, and the extended surface 43 is the same as the surface of the insulating layer 11 In addition, the structure A further satisfies the following condition. The at least one second bulk acoustic wave resonance structure 3 ′ has a second frequency adjustment structure 50 ′, and the second frequency adjustment structure 50 ′ is formed on the extended surface 43, and at least one second Between the bulk acoustic wave resonance structure 3 ′ and the at least one second hole 40 ′. The second frequency adjustment structure 50 ′ has a film thickness T2, which is the thickness of at least one first bulk acoustic wave resonance structure 3 and at least one second bulk acoustic wave resonance structure 3 ′. Correlate with the first resonance frequency difference FD1. (2) In the embodiments of FIGS. 2F, 2I, 4F, and 4H, the structure for adjusting the frequency has the surface on which the insulating layer 11 is polished, and the extended surface 43 is the same as the surface of the insulating layer 11. Further, it is composed of a structure B that satisfies the following condition. At least one first bulk acoustic wave resonant structure 3 and at least one second bulk acoustic wave resonant structure 3 'have a first frequency tuning structure 50 and a second frequency tuning structure 50', respectively. A first frequency adjustment structure 50 is formed under the extended surface 43 and is positioned between the bottom electrode layer 30 and the at least one first hole 40 of the at least one first bulk acoustic wave resonance structure 3. A second frequency tuning structure 50 ′ is formed under the extended surface 43, and is interposed between the bottom electrode layer 30 and at least one second hole 40 ′ of at least one second bulk acoustic wave resonance structure 3 ′. To position. The first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ have a first film thickness difference TD1, and the first film thickness difference TD1 is at least one first bulk acoustic wave resonance structure. 3 and at least one second bulk acoustic wave resonant structure 3 'correlate with the first resonant frequency difference FD1. (3) In the embodiments of FIGS. 3G, 3L, 4D, and 4I, the structure for adjusting the frequency is such that the second polishing layer 51 is formed on the insulating layer 11 above the plurality of holes, The second polishing layer 51 has a polishing surface, the extended surface 43 is the same as the polishing surface, and further comprises a structure C that satisfies the following conditions. Under the extended surface 43, there is at least one second polishing layer 51 located between the bottom electrode layer 30 of the at least one first bulk acoustic wave resonance structure 3 and the at least one first hole 40. The first frequency adjustment structures 50 of the two first bulk acoustic wave resonance structures 3 are formed. Under the extended surface 43, a second polishing layer 51 located between the bottom electrode layer 30 of the at least one second bulk acoustic wave resonance structure 3 ′ and the at least one second hole 40 ′, A second frequency adjustment structure 50 ′ of at least one second bulk acoustic wave resonance structure 3 ′ is formed. The first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ have a first film thickness difference TD1, and the first film thickness difference TD1 is at least one first bulk acoustic wave resonance structure. 3 and at least one second bulk acoustic wave resonant structure 3 'correlate with the first resonant frequency difference FD1. In the embodiments of FIGS. 2F, 2I, 3G, 3L, 4D, 4F, 4H, and 4I of the present application, the common feature is that the bottom electrode layer 30 of at least one first bulk acoustic wave resonant structure 3 and at least That is, the bottom electrode layer 30 of one second bulk acoustic wave resonance structure 3 ′ is formed on the extended surface 43. Furthermore, the first frequency adjustment structure 50 and the second frequency adjustment structure 50 ′ are formed below the expansion surface 43. In the embodiments of FIGS. 2H, 2J, 3I, and 3K of the present application, the common feature is that the bottom electrode layer 30 of the at least one first bulk acoustic wave resonant structure 3 and the at least one second bulk acoustic wave. That is, the bottom electrode layer 30 of the resonance structure 3 ′ is formed on the extended surface 43. Furthermore, the second frequency adjustment structure 50 ′ is formed below the expansion surface 43.

The present application further provides a method of manufacturing a bulk acoustic wave resonance device with a mass adjustment structure. See Figures 6A-6C. This drawing is a series of cross-sectional views for explaining an embodiment of a method for producing a bulk acoustic wave resonance device with a mass adjusting structure of the present application. The method for manufacturing the bulk acoustic wave resonance device 1 with the mass adjusting structure of the present application includes the following steps.
Step D1: A sacrificial mesa structure 6 is formed on the substrate 10. However, the sacrificial mesa structure 6 is divided into a plurality of parts (7) including a central part 70 and a peripheral part 71. Here, the peripheral portion 71 of the sacrificial mesa structure 6 is a periphery surrounding the central portion 70 of the sacrificial mesa structure 6. The width of the peripheral portion 71 of the sacrificial mesa structure 6 is X1.
Step D2: The mesa structure 6 is etched so that any two adjacent portions of the sacrificial mesa structure 6 have different heights. (The central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 have a height difference Y1.) Here, the highest portion of the sacrificial mesa structure 6 (the central portion 70 in this embodiment) is the highest mesa. The uppermost mesa upper surface coincides with the mesa upper surface 44. (See Figure 6A.)
Step D3: An insulating layer 11 is formed on the sacrificial mesa structure 6 and the substrate 10. However, the insulating layer 11 is made of at least one material selected from the group consisting of a silicon nitride film (SiNx), a silicon oxide film (SiO2), and a polymer.
Step D4: The insulating layer 11 is polished by a chemical mechanical planarization process to form a polished surface 41. (See FIG. 6B.) However, the portions (7) of the sacrificial mesa structure 6 have a certain geometric configuration.
Step D5: A bulk acoustic wave resonance structure 300 is formed on the polished surface 41. However, the bulk acoustic wave resonance structure 300 is located on the sacrificial mesa structure 6. Further, this step D5 comprises the following steps.
Step D51: A bottom electrode layer 30 is formed on the polished surface 41.
Step D52: The piezoelectric layer 31 is formed on the bottom electrode layer 30.
Step D53: The upper electrode layer 32 is formed on the piezoelectric layer 31.
Step D6: The sacrificial mesa structure 6 is etched to form a hole 400. However, the hole 400 is located under the bulk acoustic wave resonance structure 300. (See Figure 6C.)
In step D4, the insulating layer 11 is polished so that the sacrificial mesa structure 6 is not exposed. However, the insulating layer 11 located under the bulk acoustic wave resonance structure 300, above the hole 400, and between the polishing surface 41 and the upper part 44 of the entire mesa forms a frequency adjustment structure, and the frequency The film thickness of the adjustment structure is T. Further, the insulating layer 11 located under the bulk acoustic wave resonance structure 300 and between the upper part 44 of the entire mesa surface and the hole 400 forms the mass adjustment structure 8.
In the present embodiment, the mass adjustment structure 8 includes a peripheral mass adjustment structure 81. The position of the peripheral mass adjusting structure 81 corresponds to the peripheral portion 71 of the sacrificial mesa structure 6. The width (X1) of the peripheral mass adjusting structure 81 is the same as the width X1 of the peripheral portion 71 of the sacrificial mesa structure 6. The thickness (Y1) of the peripheral mass adjusting structure 81 is the same as the height difference Y1 of the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6. By forming the mass adjustment structure 8, an acoustic wave resonance film including the upper electrode layer 32, the piezoelectric layer 31, and the bottom electrode layer 30 of the bulk acoustic wave resonance structure 300 of the bulk acoustic wave resonance device 1 is formed. The boundary condition of the peripheral part changes. Since the boundary condition of the peripheral portion of the bulk acoustic wave resonance structure 300 is changed, the reflected acoustic wave with respect to the incident acoustic wave is reflected when the incident acoustic wave is reflected on the peripheral portion of the bulk acoustic wave resonance structure 300. The ratio of changes. The geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6 is related to the geometric configuration of the mass adjustment structure 8. Therefore, by designing and adjusting the size of the geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6, the size of the geometric configuration of the mass adjustment structure 8 is adjusted. (In this embodiment, for example, the thickness Y1 and the width X1 of the peripheral mass adjusting structure 81 are designed and adjusted.) Thus, the Q factor of the bulk acoustic wave resonator 1 is effectively enhanced. As a result, the ratio of the reflected acoustic wave to the incident acoustic wave is adjusted, and as a result, the spurious mode of the bulk acoustic wave resonator 1 is suppressed. Further, in this embodiment, the insulating layer 11 can effectively enhance the mechanical structure strength of the bulk acoustic wave resonance structure 300. Therefore, even if stress is applied, the bulk acoustic wave resonance structure 300 does not bend and contact the substrate 10, and the characteristics of the acoustic wave resonance device 1 are not affected. In addition, it is possible to prevent the bulk acoustic wave resonance structure 300 of the bulk acoustic wave resonance device 1 from collapsing by increasing the mechanical strength of the bulk acoustic wave resonance structure 300 of the bulk acoustic wave resonance device 1. Become. In one embodiment, the substrate 10 is a semiconductor substrate and the sacrificial mesa structure 6 is made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures.

In one embodiment, the substrate 10 is a compound semiconductor, and the step D1 includes the following steps.
Step D11: A sacrificial structure 21 is formed on the substrate 10.
Step D12: The sacrificial structure 21 is etched to form the sacrificial mesa structure 6.
In one embodiment, the substrate 10 comprises GaAs and the sacrificial structure 21 comprises a GaAs layer. Alternatively, in another embodiment, the substrate 10 is made of InP and the sacrificial structure 21 is made of an InGaAs layer. In one embodiment, the sacrificial structure 21 includes a sacrificial epitaxial layer 27, a first etching stop layer 22, and a first fine adjustment layer 23. However, the sacrificial epitaxial layer 27 is formed on the substrate 10, the first etching stop layer 22 is formed on the sacrificial epitaxial layer 27, and the first fine adjustment layer 23 is formed on the first fine adjustment layer 23. It is formed on the etching stop layer 22. (See FIG. 2K.) The height difference Y 1 between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 is determined by the film thickness of the first fine adjustment layer 23. Therefore, this serves to accurately adjust the film thickness (Y1) of the peripheral mass adjusting structure 81, so that the Q factor of the bulk acoustic wave resonance device 1 is accurately enhanced, and as a result, the bulk acoustic wave It becomes possible to suppress the spurious mode of the resonance device 1 accurately.

  Refer to FIGS. 6D-6E. This figure is a series of cross-sectional views for explaining another embodiment of the method of manufacturing the bulk acoustic wave resonance device with a mass adjusting structure of the present application. 6E is basically the same as that shown in FIG. 6C except that the insulating layer 11 is polished so that the sacrificial mesa structure 6 is exposed in step D4 (see FIG. 6D). It is the same as the step of forming the embodiment. However, the insulating layer 11 located under the bulk acoustic wave resonance structure 300 and between the polishing surface 41 and the holes 400 forms the mass adjustment structure 8. (See FIG. 6E.) The geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6 is related to the geometric configuration of the mass adjustment structure 8. Therefore, by adjusting the geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6, the mass adjustment structure 8 of the mass adjustment structure 8 is enhanced so that the Q factor of the bulk acoustic wave resonance device 1 is enhanced. The geometric configuration can be adjusted. As a result, the spurious mode of the bulk acoustic wave resonator 1 can be suppressed. In the present embodiment, the mass adjustment structure 8 includes a peripheral mass adjustment structure 81. The position of the peripheral mass adjusting structure 81 corresponds to the peripheral portion 71 of the sacrificial mesa structure 6. The width (X1) of the peripheral mass adjusting structure 81 is equal to the width X1 of the peripheral portion 71 of the sacrificial mesa structure 6. The insulating layer 11 is polished until the sacrificial mesa structure 6 is exposed such that the polishing surface 41 coincides with the mesa upper surface 44 or the polishing surface 41 is lower than the mesa upper surface 44. . Therefore, the film thickness (Y1 ′) of the peripheral mass adjusting structure 81 is equal to or less than the height difference Y1 between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6.

Furthermore, the present application provides a method of manufacturing a bulk acoustic wave resonant structure with a mass adjusting structure. Refer to FIGS. 6F-6H. These are a series of sectional views for explaining an embodiment of a method for producing a bulk acoustic wave resonance device with a mass adjusting structure of the present application. The method for manufacturing the bulk acoustic wave resonance device 1 with the mass adjusting structure of the present application includes the following steps.
Step E1: A sacrificial mesa structure 6 is formed on the substrate 10.
Step E2: An insulating layer 11 is formed on the sacrificial mesa structure 6 and the substrate 10. However, the insulating layer 11 is made of at least one material selected from the group consisting of a silicon nitride film (SiNx), a silicon oxide film (SiO2), and a polymer.
Step E3: The pre-polished surface 42 is formed by polishing the insulating layer 11 by a prior chemical mechanical planarization process so that the sacrificial mesa structure 6 is exposed. However, the sacrificial mesa structure 6 is divided into a plurality of portions (7) including the central portion 70 and the peripheral portion 71. The peripheral portion 71 of the sacrificial mesa structure 6 is a peripheral region surrounding the central portion 70. The width of the peripheral portion 71 of the sacrificial mesa structure 6 is X1. (Steps E1, E2 and E3 are similar to the steps of FIGS. 3A and 3B, except that there is only one sacrificial mesa structure 6.)
Step E4: The sacrificial mesa structure 6 is formed such that any two adjacent portions of the sacrificial mesa structure 6 (the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6) have different heights. Etch. However, the highest portion of the sacrificial mesa structure 6 (the central portion 70 in the present embodiment) has the highest mesa upper surface, and the highest mesa upper surface coincides with the upper mesa upper surface 44. The mesa upper surface 44 coincides with the pre-polished surface 42 and the portions (7) of the sacrificial mesa structure 6 have a geometric configuration. (See Figure 6F.)
Step E5: The bulk acoustic wave resonance structure 300 is formed. However, the bulk acoustic wave resonance structure 300 is located above the sacrificial mesa structure 6, and the step E5 further includes the following steps.
Step E51: A second polishing layer 51 is formed on the sacrificial mesa structure 6 and the insulating layer 11. However, the second polishing layer 51 is made of an insulator. In a preferred embodiment, the second polishing layer 51 is made of at least one material selected from the group consisting of a silicon nitride film (SiNx), a silicon oxide film (SiO2), an aluminum nitride film (AlN), and a polymer. . However, the polymer may contain benzocyclobutane (BCB).
Step E52: Using a chemical mechanical planarization process, the second polishing layer 51 is polished to the extent that the sacrificial mesa structure 6 is not exposed to form a polishing surface 41. (See Figure 6G.)
Step E53: A bottom electrode layer 30 is formed on the polishing surface 41.
Step E54: The piezoelectric layer 31 is formed on the bottom electrode layer 30.
Step E55: An upper electrode 32 is formed on the piezoelectric layer 31.
Step E6: The sacrificial mesa structure 6 is etched to form a hole 400. (See FIG. 6H.) The holes 400 are located below the bulk acoustic wave resonance structure 300.
The second polishing layer 51 located below the bulk acoustic wave resonance structure 300, above the void 400, and between the polishing surface 41 and the mesa upper surface 44 forms a frequency adjustment structure. However, the film thickness of the frequency adjustment structure is T. The second polishing layer 51 located below the bulk acoustic wave resonance structure 300 and between the upper part 44 of the entire mesa surface and the holes 400 forms the mass adjustment structure 8.
The geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6 is related to the geometric configuration of the mass adjustment structure 8. Therefore, by adjusting the geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6, the geometry of the mass adjustment structure 8 is enhanced so as to enhance the Q factor of the bulk acoustic wave resonance device 1. The overall structure. As a result, the spurious mode of the bulk acoustic wave resonator 1 can be reduced. In the present embodiment, the mass adjustment structure 8 includes a peripheral mass adjustment structure 81. The position of the peripheral mass adjusting structure 81 corresponds to the peripheral portion 71 of the sacrificial mesa structure 6. The width (X1) of the peripheral mass adjusting structure 81 is equal to the width X1 of the peripheral portion 71 of the sacrificial mesa structure 6. The film thickness (Y1) of the peripheral mass adjusting structure 81 is equal to the height difference Y1 between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6. In one embodiment, the substrate 10 is a semiconductor substrate. The sacrificial mesa structure 6 is made of at least one material selected from the group consisting of metals, alloys, and epitaxial layers.

In another embodiment, the substrate 10 is a compound semiconductor substrate. Step E1 includes the following steps.
Step E11: A sacrificial structure 21 is formed on the substrate 10.
Step E12: The sacrificial structure 21 is etched to form the sacrificial mesa structure 6.
In one embodiment, the substrate 10 comprises GaAs and the sacrificial structure 21 comprises a GaAs layer. Alternatively, in another embodiment, the substrate 10 is made of InP and the sacrificial structure 21 is made of an InGaAs layer. In one embodiment, the sacrificial structure 21 includes a sacrificial epitaxial layer 27, a first etching stop layer 22, and a first fine adjustment layer 23. However, the sacrificial epitaxial layer 27 is formed on the substrate 10, the first etching stop layer 22 is formed on the sacrificial epitaxial layer 27, and the first fine adjustment layer 23 is formed on the first fine adjustment layer 23. It is formed on the etching stop layer 22. (See FIG. 2K.) The height difference Y1 between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 is determined by the film thickness of the first fine adjustment layer 23. Therefore, this serves to accurately adjust the film thickness (Y1) of the peripheral mass adjusting structure 81, so that the Q factor of the bulk acoustic wave resonance device 1 is accurately enhanced, and as a result, the bulk acoustic wave It becomes possible to suppress the spurious mode of the resonance device 1 accurately.

  Refer to FIGS. 6I-6K. These are a series of cross-sectional views for explaining another embodiment of the method of manufacturing the bulk acoustic wave resonance device with a mass adjusting structure of the present application. The main step of manufacturing the embodiment of FIG. 6H is that the sacrificial mesa structure 6 is etched in step E4 so that any two adjacent portions of the sacrificial mesa structure 6 have different heights. This is the same as the step of manufacturing the embodiment of FIG. 6K. (The height difference between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 is actually Y1.) Here, the highest portion of the sacrificial mesa structure 6 (the central portion 70 in the present embodiment) is A top mesa top surface, the top mesa top surface coinciding with the top mesa top 44. The mesa upper surface 44 is lower than the pre-polished surface 42, and the portions (7) of the sacrificial mesa structure 6 have a geometric configuration. (See FIG. 6I.) Reference is made to FIG. 6J. This figure shows a state after step E52. After step E6, the second polishing layer 51 located below the bulk acoustic wave resonance structure 300, above the air holes 400, and between the polishing surface 41 and the mesa upper surface 44 has a frequency adjustment. Form a structure. The thickness of the frequency adjustment structure is T. The second polishing layer 51 located under the bulk acoustic wave resonance structure 300 and between the upper part 44 of the entire mesa surface and the holes 400 forms a mass adjustment structure 8. (See Figure 6K.)

Furthermore, this application provides the manufacturing method of the bulk acoustic wave resonance apparatus with a mass adjustment structure. Reference is now made to FIGS. 6L-6M. These drawings are a series of cross-sectional views for explaining an embodiment of a method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure of the present application. The manufacturing method of the bulk acoustic wave resonance apparatus 1 with a mass adjustment structure of the present application includes the following steps.
Step F1: A sacrificial mesa structure 6 is formed on the substrate 10.
Step F2: An insulating layer 11 is formed on the sacrificial mesa structure 6 and the substrate 10. However, the insulating layer 11 is made of at least one material selected from the group consisting of a silicon nitride film (SiNx), a silicon oxide film (SiO2), and a polymer.
Step F3: The pre-polishing layer 42 is formed by polishing the insulating layer 11 by a prior chemical mechanical planarization process so that the sacrificial mesa structure 6 is exposed. However, the sacrificial mesa structure 6 is divided into a plurality of portions (7) including the central portion 70 and the peripheral portion 71.
Here, the peripheral portion 71 of the sacrificial mesa structure 6 is a periphery surrounding the central portion 70 of the sacrificial mesa structure 6. However, the width of the peripheral portion 71 of the sacrificial mesa structure 6 is X1. (Steps F1, F2 and F3 are similar to the steps of FIGS. 3A and 3B, except that there is only one sacrificial mesa structure 6.)
Step F4: The sacrificial mesa structure 6 is etched so that any two adjacent portions of the sacrificial mesa structure 6 have different heights. (The central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 have a height difference Y1.) Here, the uppermost portion of the sacrificial mesa structure 6 is the upper surface of the highest mesa. The highest mesa upper surface coincides with the mesa upper surface 44.
However, the mesa upper surface 44 coincides with the pre-polished surface 42 and the plurality of portions (7) of the sacrificial mesa structure 6 have a geometric configuration. (See Figure 6F.)
Step F5: The bulk acoustic wave resonance structure 300 is formed. However, the bulk acoustic wave resonance structure 300 is located above the sacrificial mesa structure 6, and the step F5 further includes the following steps.
Step F51: A second polishing layer 51 is formed on the sacrificial mesa structure 6 and the insulating layer 11. However, the second polishing layer 51 is made of at least one material selected from the group consisting of metals and alloys.
In a preferred embodiment, the second polishing layer 51 is made of a material selected from the group consisting of ruthenium, titanium, molybdenum, platinum, gold, aluminum, and tungsten.
Step F52: Using a chemical mechanical planarization process, the second polishing layer 51 is polished to the extent that the sacrificial mesa structure 6 is not exposed to form a polishing surface 41. (See Figure 6G.)
Step F53: Pattern the second polishing layer 51. (See Figure 6L.)
Step F54: The piezoelectric layer 31 is formed on the polishing surface 41 of the second polishing layer 51 and the preliminary polishing surface 42 of the insulating layer 11.
Step F55: An upper electrode 32 is formed on the piezoelectric layer 31.
Step F6: The sacrificial mesa structure 6 is etched to form a hole 400. However, the hole 400 is located below the bulk acoustic wave resonance structure 300.
The second polishing layer 51 located below the piezoelectric layer 31, above the pores 400, and between the polishing surface 41 and the mesa upper surface 44 is a bottom electrode of the bulk acoustic wave resonance structure 300. Layer 30 is formed. The second polishing layer 51 located below the bulk acoustic wave resonance structure 300 and between the upper part 44 of the entire mesa surface and the holes 400 forms a mass adjustment structure. (See Figure 6M.)
The Qianye geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6 is related to the geometric configuration of the mass adjusting structure 8, and the plurality of portions (7 of the sacrificial mesa structure 6) The geometric configuration of the mass adjusting structure 8 is adjusted so as to enhance the Q factor of the bulk acoustic wave resonance device 1 by adjusting the geometric configuration of As a result, the spurious mode of the bulk acoustic wave resonator 1 is reduced. In the present embodiment, the mass adjustment structure 8 includes a peripheral mass adjustment structure 81. The position of the peripheral mass adjusting structure 81 corresponds to the peripheral portion 71 of the sacrificial mesa structure 6. The width (X1) of the peripheral mass adjusting structure 81 is the same as the width X1 of the peripheral portion 71 of the sacrificial mesa structure 6. The thickness (Y1) of the peripheral mass adjusting structure 81 is the same as the height difference Y1 of the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6. In one embodiment, the substrate 10 is a semiconductor substrate and the sacrificial mesa structure 6 is made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures.

In another embodiment, the substrate 10 is a compound semiconductor substrate. Step F1 includes the following steps.
Step F11: A sacrificial structure 21 is formed on the substrate 10.
Step F12: The sacrificial structure 21 is etched to form the sacrificial mesa structure 6.
In one embodiment, the substrate 10 comprises GaAs and the sacrificial structure 21 comprises a GaAs layer. Alternatively, in another embodiment, the substrate 10 is made of InP and the sacrificial structure 21 is made of an InGaAs layer. In one embodiment, the sacrificial structure 21 includes a sacrificial epitaxial layer 27, a first etching stop layer 22, and a first fine adjustment layer 23. However, the sacrificial epitaxial layer 27 is formed on the substrate 10, the first etching stop layer 22 is formed on the sacrificial epitaxial layer 27, and the first fine adjustment layer 23 is formed on the first fine adjustment layer 23. It is formed on the etching stop layer 22. (See FIG. 2K.) The height difference Y 1 between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 is determined by the film thickness of the first fine adjustment layer 23. Therefore, this serves to accurately adjust the film thickness (Y1) of the peripheral mass adjusting structure 81, so that the Q factor of the bulk acoustic wave resonance device 1 is accurately enhanced, and as a result, the bulk acoustic wave It becomes possible to suppress the spurious mode of the resonance device 1 accurately.

  Refer to FIGS. 6N-6O. This figure is a series of cross-sectional views for explaining another embodiment of the method of manufacturing the bulk acoustic wave resonance device with a mass adjusting structure of the present application. The main steps for fabricating the embodiment of FIG. 6O are that the sacrificial mesa structure 6 is etched in step F4 such that any two adjacent portions of the sacrificial mesa structure 6 have different heights. 6M is the same as the step of manufacturing the embodiment of FIG. (The height difference between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 is actually Y1.) Here, the highest portion of the sacrificial mesa structure 6 (the central portion 70 in this embodiment) is The uppermost mesa upper surface has a top mesa upper surface that coincides with the upper mesa upper surface 44. The mesa upper surface 44 is lower than the pre-polished surface 42, and the portions (7) of the sacrificial mesa structure 6 have a geometric configuration. (See FIG. 6I.) Reference is made to FIG. 6J. This figure shows a state after step F52. Reference is now made to FIG. This figure shows the state after step F53. After Step F6, the second polishing layer 51 located below the piezoelectric layer 31, above the hole 400, and between the polishing surface 41 and the upper part of the entire mesa 44 is formed by the bulk acoustic wave resonance structure. 300 bottom electrode layers 30 are formed. The second polishing layer 51 located under the bulk acoustic wave resonance structure 300 and between the mesa upper surface 44 and the holes 400 forms a mass adjustment structure. (See Figure 6O.)

  Refer to FIGS. 6P-6Q. This figure is a series of cross-sectional views for explaining another embodiment of the method of manufacturing the bulk acoustic wave resonance device with a mass adjusting structure of the present application. The main steps forming the embodiment of FIG. 6Q are the implementation of FIG. 6C, except that in step D1, the plurality of sites (7) include a central portion 70, a peripheral portion 71 and a second peripheral portion 72. The same steps as the example are formed. However, the second peripheral portion 72 of the sacrificial mesa structure 6 surrounds the periphery of the central portion 70 of the sacrificial mesa structure 6, and the peripheral portion 71 of the sacrificial mesa structure 6 Surrounding the periphery of the second peripheral portion 72, the second peripheral portion 72 of the sacrificial mesa structure 6 is located between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6. However, the width of the peripheral portion 71 of the sacrificial mesa structure 6 is X1, and the width X2 of the second peripheral portion 72 is. In step D2, the sacrificial mesa structure 6 is etched such that any two adjacent portions of the sacrificial mesa structure 6 have different heights. (That is, the two adjacent portions, the central portion 70 and the second peripheral portion 72 of the sacrificial mesa structure 6 have different heights, and the two adjacent portions, The second peripheral portion 72 and the peripheral portion 71 have different heights.) Here, the uppermost portion of the sacrificial mesa structure 6 (the central portion 70 in this embodiment) is the uppermost mesa upper surface. Have. The highest mesa upper surface coincides with the mesa upper surface 44. The height difference between the central portion 70 (uppermost portion) and the second peripheral portion 72 of the sacrificial mesa structure 6 is Y2, and the central portion 70 (uppermost portion) and the peripheral portion 71 of the sacrificial mesa structure 6 are The height difference is Y1. However, the plurality of portions (7) of the sacrificial mesa structure 6 have a certain geometric configuration. (See FIG. 6P.) In step D4, the insulating layer 11 is polished to such an extent that the sacrificial mesa structure 6 is not exposed. The insulating layer 11 located below the bulk acoustic wave resonance structure 300, above the holes 400, and between the polishing surface 41 and the upper part 44 of the entire mesa forms a frequency adjustment structure, and the frequency adjustment The film thickness of the structure is T. The insulating layer 11 located under the bulk acoustic wave resonance structure 300 and between the mesa upper surface 44 and the air holes 400 forms a mass adjustment structure 8. The geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6 is related to the geometric configuration of the mass adjustment structure 8. Therefore, by adjusting the geometric configuration of the plurality of portions (7) of the sacrificial mesa structure 6, the geometry of the mass adjustment structure 8 is increased so as to enhance the Q factor of the bulk acoustic wave resonance device 1. The configuration can be adjusted. As a result, the spurious mode of the bulk acoustic wave resonator 1 can be suppressed. In this embodiment, the mass adjustment structure 8 includes a peripheral mass adjustment structure 81 and a second peripheral mass adjustment structure 82. The position of the peripheral mass adjustment structure 81 corresponds to the peripheral portion 71 of the sacrificial mesa structure 6, and the position of the second mass adjustment structure 82 corresponds to the second peripheral portion 72. The width (X1) of the peripheral mass adjustment structure 81 is equal to the width X1 of the peripheral portion 71 of the sacrificial mesa structure 6, and the width (X2) of the second peripheral mass adjustment structure 82 is the sacrificial mesa structure 6. Is equal to the width X2 of the second peripheral portion 72. The thickness (Y1) of the peripheral mass adjustment structure 81 is the same as the height difference Y1 of the central portion 70 and the first peripheral portion 71 of the sacrificial mesa structure 6, and the second peripheral mass adjustment structure 82 The thickness (Y2) is the same as the height difference Y2 of the central portion 70 and the second peripheral portion 72 of the sacrificial mesa structure 6. In one embodiment, the substrate 10 is a semiconductor substrate and the sacrificial mesa structure 6 is made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures.

  In another embodiment, the substrate 10 is a compound semiconductor substrate. In another embodiment, the substrate 10 comprises GaAs and the sacrificial structure 21 comprises a GaAs layer. Alternatively, in another embodiment, the substrate 10 is made of InP and the sacrificial structure 21 is made of an InGaAs layer. In one embodiment, the sacrificial structure 21 comprises a sacrificial epitaxial layer 27, a second etching stop layer 24 and a second fine adjustment layer 25, a first etching stop layer 22 and a first fine adjustment layer 23. However, the sacrificial epitaxial layer 27 is formed on the substrate 10, the second etching stop layer 24 is formed on the sacrificial epitaxial layer 27, and the second fine adjustment layer 25 is formed on the second fine adjustment layer 25. The first etching stop layer 22 is formed on the second fine adjustment layer 25, and the first fine adjustment layer 23 is formed on the first etching stop layer 22. Formed on. (See FIG. 5.) In some embodiments, the substrate 10 is formed of GaAs. The sacrificial epitaxial layer 27 is made of GaAs. The first etching stop layer 22 is formed of AlAs or InGaP, and the film thickness ET1 is between 1 nanometer and 50 nanometers. The first fine adjustment layer 23 is made of GaAs, and its film thickness FT1 is between 1 nanometer and 300 nanometers. The second etching stop layer 24 is made of AlAs or InGaP and has a film thickness between 1 nanometer and 50 nanometers. The second fine adjustment layer 25 is made of GaAs, and its film thickness FT2 is between 1 nanometer and 300 nanometers. In some embodiments, the substrate 10 is formed of InP. The sacrificial epitaxial layer 27 is made of InGaAs. The first etching stop layer 22 is made of InP, and its film thickness ET1 is between 1 nanometer and 50 nanometers. The first fine adjustment layer 23 is made of InGaAs, and its film thickness FT1 is between 1 nanometer and 300 nanometers. The second etching stop layer 24 is made of InP and has a thickness between 1 nanometer and 50 nanometers. The second fine adjustment layer 25 is made of InGaAs, and its film thickness FT2 is between 1 nanometer and 300 nanometers. The height difference Y1 between the central portion 70 and the peripheral portion 71 of the sacrificial mesa structure 6 depends on the film thickness of the first fine adjustment layer 23, the film thickness of the first etching stop layer 22, and the second It depends on the film thickness of the fine adjustment layer 25. The height difference Y2 between the central portion 70 and the second peripheral portion 72 of the sacrificial mesa structure 6 is determined by the film thickness of the first fine adjustment layer 23. Therefore, this serves to accurately adjust the film thickness (Y1) of the peripheral mass adjustment structure 81 and the film thickness (Y2) of the second peripheral mass adjustment structure 82. The Q factor is accurately increased, and as a result, the spurious mode of the bulk acoustic wave resonance device 1 can be accurately suppressed.

  In one embodiment, the peripheral portion 71 of the sacrificial mesa structure 6 has a top mesa top surface. The highest mesa upper surface coincides with the mesa upper surface 44. Two adjacent portions of the sacrificial mesa structure 6, that is, the central portion 70 and the second peripheral portion 72 have different heights. Further, the other two adjacent portions of the sacrificial mesa structure 6, that is, the second peripheral portion 72 and the peripheral portion 71 have different heights. The mass adjustment structure 8 includes a central peripheral mass adjustment structure and a second peripheral mass adjustment structure 82. (Not shown.) In another embodiment, the second peripheral portion 72 of the sacrificial mesa structure 6 has a top mesa top surface. However, the uppermost mesa upper surface coincides with the mesa upper surface 44. Two adjacent portions of the sacrificial mesa structure 6, that is, the central portion 70 and the second peripheral portion 72 have different heights. Two other adjacent portions of the sacrificial mesa structure 6, that is, the second peripheral portion 72 and the peripheral portion 71 have different heights. The mass adjustment structure 8 includes a central peripheral mass adjustment structure and a peripheral mass adjustment structure 81. (Not shown.) In general, the mass adjustment structure 8 in the embodiment of FIGS. 6E, 6H, 6K, 6M and 6O is similar to the mass adjustment structure 8 in the embodiment of FIG. 6Q.

  Refer to FIG. 6R. This figure is a cross-sectional view for explaining an embodiment of a method for producing a bulk acoustic wave resonance device with a mass adjusting structure of the present application. The main structure of the embodiment of FIG. 6R is that of FIG. 6C except that the bottom etching layer 20 is formed on the substrate 10 and the insulating layer 11 is formed on the bottom etching stop layer 20. The structure is the same as that of the example. In step D6, the bottom etching stop layer 20 prevents the etching from proceeding further downward. In another embodiment, the substrate 10 is a compound semiconductor substrate. In one embodiment, the substrate 10 is made of GaAs, the sacrificial structure 21 is made of a GaAs layer, and the bottom etching stop layer 20 is made of InGaP. In another embodiment, the substrate 10 is made of InP, the sacrificial structure 21 is made of an InGaAs layer, and the bottom etching stop layer 20 is made of InP. In general, the embodiment of FIGS. 6E, 6H, 6K, 6M, 6O and 6Q is comprised of a bottom etch stop layer 20 as seen in the embodiment of FIG. 6R.

  Refer to FIG. This figure is a top electrode view showing an embodiment of a method for producing a bulk acoustic wave resonance device with a mass adjusting structure of the present application. In the embodiment of FIG. 6S, the main structure is composed of a hole 400, a bottom electrode layer 30, a piezoelectric layer 31, an upper electrode layer 32, a peripheral mass adjustment structure 81, and a second peripheral mass adjustment structure 82. . A cross-sectional view taken along the dividing line a-a ′ in FIG. 6S is the embodiment of FIG. 6Q. The hole 400 is located under the bottom electrode layer 30. The piezoelectric layer 31 is formed on the bottom electrode layer 30. The upper electrode layer 32 is formed on the piezoelectric layer 31. The upper surface electrode diagram of the embodiment of FIG. 6S is an example of the shape of the bulk acoustic wave resonance device with a mass adjustment structure of the present application. The shape of the bulk acoustic wave resonance device with a mass adjusting structure of the present application is various. 6C, 6E, 6H, 6K, 6M, 6O, or 6R may have a top view (shape) similar to that of FIG. 6S or various shapes.

  By changing the width of the upper electrode layer 32, it is possible to change the boundary condition of the peripheral portion of the bulk acoustic wave resonance structure 300. Therefore, the present application combines the adjustment of the mass adjustment structure 8 and the upper electrode layer 32 of the bulk acoustic wave resonance structure 300 so as to effectively enhance the Q factor of the bulk acoustic wave resonance device 1. As a result, the spurious mode of the bulk acoustic wave resonator 1 is suppressed. 6C, 6E, 6H, 6K, 6M, 6O, 6Q, and 6R, and the like, the width of the upper electrode layer 32 of the bulk acoustic wave resonance structure 300 is equal to or less than the width of the hole 400. It is. In another embodiment, the width of the upper electrode layer 32 of the bulk acoustic wave resonance structure 300 is less than or equal to the width of the central portion 70 of the sacrificial mesa structure 6.

  In one embodiment, the mass adjusting structure 8 is made of a metal material or an insulating material. The metal substance is at least one material selected from the group consisting of titanium, molybdenum, platinum, aluminum, gold, tungsten, and rubidium. The insulating material is at least one material selected from the group consisting of a silicon oxide film, a silicon nitride film, an aluminum nitride film, and a polymer. The polymer can include benzocyclobutane (BCB). In one embodiment, the mass adjusting structure 8 may include a combination of the above metal materials or insulating materials.

  In the embodiment of the present application, the material of the bottom electrode layer 30 is at least one material selected from the group consisting of titanium, molybdenum, platinum, aluminum, gold, tungsten, and rubidium. The material of the upper electrode layer 32 is a material selected from the group consisting of titanium, molybdenum, platinum, aluminum, gold, tungsten, and rubidium. In an embodiment of the present application, the material of the piezoelectric layer 31 is composed of an aluminum nitride film. In one embodiment of the present application, the material of the piezoelectric layer 31 is composed of an aluminum nitride film doped with scandium. In another embodiment of the present application, the material of the piezoelectric layer 31 is composed of zinc oxide.

  As described above with reference to the accompanying drawings, the present application provides a method of manufacturing a bulk acoustic wave resonance device with a mass adjustment structure. It is new and has industrial utility value.

Although the embodiments of the present application have been described in detail, it is possible to devise many modifications and variations by those who have general skills in the field based on the knowledge described here. . Therefore, any modification or variation equivalent to the spirit of this application is considered to be within the scope defined by the following claims.

Claims (18)

It consists of the following steps D1 to D6,
In the step D1, a sacrificial mesa structure is formed on the substrate, the sacrificial mesa structure is divided into a plurality of parts,
In step D2, the mesa structure is etched such that any two adjacent portions of the sacrificial mesa structure have different heights, and the top of the sacrificial mesa structure has a top mesa upper surface. The top surface of the highest mesa coincides with the top of the entire mesa surface,
In step D3, an insulating layer is formed on the sacrificial mesa structure and the substrate,
In step D4, the insulating layer is polished by a chemical mechanical planarization process to form a polished surface;
In step D5, a bulk acoustic wave resonance structure is formed on the polished surface, and the bulk acoustic wave resonance structure is located on the sacrificial mesa structure,
Step D5 further comprises Step D51, Step D52 and Step D53,
In step D51, forming a bottom electrode layer on the polished surface;
In step D52, a piezoelectric layer is formed on the bottom electrode layer,
In step D53, an upper electrode layer is formed on the piezoelectric layer,
In step D6, the sacrificial mesa structure is etched to form vacancies, the vacancies are located under the bulk acoustic wave resonance structure,
In the step D4, (1) the insulating layer is polished to such an extent that the sacrificial mesa structure is not exposed, and under the bulk acoustic wave resonance structure, above the holes, and the polished surface and the entire mesa surface The insulating layer located between the upper part forms a frequency adjusting structure, and the insulating layer located under the bulk acoustic wave resonance structure and between the upper part of the entire mesa and between the holes forms a mass adjusting structure And
Or (2) polishing the insulating layer so that the sacrificial mesa structure is exposed, and adjusting the mass of the insulating layer located under the bulk acoustic wave resonance structure and between the polishing surface and the holes Forming structure,
A method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure. After the step D4, the plurality of portions of the sacrificial mesa structure have a geometric configuration, and the geometric configuration of the sacrificial mesa structure relates to a geometric configuration of the mass adjustment structure; Adjusting the geometric configuration of the mass tuning structure to enhance the Q factor of the bulk acoustic wave resonator by adjusting the geometric configuration of the sacrificial mesa structure;
The manufacturing method of the bulk acoustic wave resonance apparatus with a mass adjustment structure of Claim 1 characterized by the above-mentioned. The substrate is a semiconductor substrate, and the sacrificial mesa structure is made of at least one material selected from the group consisting of metals, alloys, and epitaxial structures.
The manufacturing method of the bulk acoustic wave resonance apparatus with a mass adjustment structure of Claim 1 characterized by the above-mentioned. The substrate is a compound semiconductor substrate, and the step D1 includes the following steps D11 and D12,
In step D11, a sacrificial structure is formed on the substrate,
In step D12, the sacrificial structure is etched to form the sacrificial mesa structure.
The manufacturing method of the bulk acoustic wave resonance apparatus with a mass adjustment structure of Claim 3 characterized by the above-mentioned. (1) the substrate is made of GaAs and the sacrificial structure is made of a GaAs layer; or (2) the substrate is made of InP and the sacrificial structure is made of an InGaAs layer.
The manufacturing method of the bulk acoustic wave resonance apparatus with a mass adjustment structure of Claim 4 characterized by the above-mentioned. Furthermore, a bottom etching stop layer is formed on the substrate, the sacrificial structure is formed on the bottom etching stop layer, the sacrificial structure is formed on the bottom etching stop layer, and (1) the bottom etching stop The layer is made of InGaP, or (2) the bottom etch stop layer is made of InP,
The method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure according to claim 5. It consists of the following steps from E1 to E6,
In step E1, a sacrificial mesa structure is formed on the substrate,
In step E2, an insulating layer is formed on the sacrificial mesa structure and the substrate,
In step E3, the insulating layer is polished by a prior chemical mechanical planarization process so that the sacrificial mesa structure is exposed to form a pre-polished surface, and the sacrificial mesa structure is divided into a plurality of portions,
In step E4, the mesa structure is etched such that any two adjacent portions of the sacrificial mesa structure have different heights, and the top of the sacrificial mesa structure has a top mesa upper surface. The top surface of the highest mesa coincides with the top of the entire mesa surface,
In the step E5, a bulk acoustic wave resonance structure is formed, the bulk acoustic wave resonance structure is located above the sacrificial mesa structure, and the step E5 further includes the following steps E51 to E55,
In step E51, a second polishing layer is formed on the sacrificial mesa structure and the insulating layer, and the second polishing layer is made of an insulator.
In step E52, a chemical mechanical planarization process is used to polish the second polishing layer to the extent that the sacrificial mesa structure is not exposed to form a polishing surface;
In step E53, a bottom electrode layer is formed on the polished surface,
In step E54, a piezoelectric layer is formed on the bottom electrode layer,
In step E55, an upper electrode is formed on the piezoelectric layer,
In step E6, the sacrificial mesa structure is etched to form a hole, and the hole is located below the bulk acoustic wave resonance structure,
The second polishing layer located below the bulk acoustic wave resonance structure, above the vacancies, and between the polishing surface and the entire upper surface of the mesa forms a frequency adjustment structure, and the bulk acoustic wave resonance structure And the second polishing layer located between the upper surface of the mesa and between the holes forms a mass adjustment structure,
A method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure, wherein: After the step E52, the plurality of portions of the sacrificial mesa structure have a geometric configuration, the geometric configuration of the sacrificial mesa structure is related to a geometric configuration of the mass adjustment structure; Adjusting the geometric configuration of the mass tuning structure to enhance the Q factor of the bulk acoustic wave resonator by adjusting the geometric configuration of the sacrificial mesa structure;
The method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure according to claim 7. The substrate is a semiconductor substrate, and the sacrificial mesa structure is made of at least one material selected from the group of metals, alloys, and epitaxial structures;
The method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure according to claim 7. The substrate is a compound semiconductor substrate, and the step E1 includes the following steps E11 and E12,
In step E11, a sacrificial structure is formed on the substrate,
In step E12, the sacrificial structure is etched to form the sacrificial mesa structure.
The method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure according to claim 9. (1) the substrate is made of GaAs and the sacrificial structure is made of a GaAs layer; or (2) the substrate is made of InP and the sacrificial structure is made of an InGaAs layer.
The manufacturing method of the bulk acoustic wave resonance apparatus with a mass adjustment structure of Claim 10 characterized by the above-mentioned. Further, a bottom etching stop layer is formed on the substrate, the sacrificial structure is formed on the bottom etching stop layer, (1) the bottom etching stop layer is made of InGaP, or (2) the bottom etching is performed. The stop layer is made of InP.
The method of manufacturing a bulk acoustic wave resonance device with a mass adjustment structure according to claim 11, It consists of the following steps F1 to F6,
In step F1, a sacrificial mesa structure is formed on the substrate,
In step F2, an insulating layer is formed on the sacrificial mesa structure and the substrate,
In step F3, the insulating layer is polished by a prior chemical mechanical planarization process so that the sacrificial mesa structure is exposed to form a preliminary polishing layer, and the sacrificial mesa structure is divided into a plurality of portions,
In step F4, the sacrificial mesa structure is etched such that any two adjacent portions of the sacrificial mesa structure have different heights, and the top of the sacrificial mesa structure is a top mesa top surface. The top surface of the highest mesa coincides with the top of the entire mesa surface,
In step F5, a bulk acoustic wave resonance structure, the bulk acoustic wave resonance structure is located above the sacrificial mesa structure, the step F5 is further configured by the following steps F51 to F55,
In Step F51, a second polishing layer is formed on the sacrificial mesa structure and the insulating layer, and the second polishing layer is made of at least one material selected from the group consisting of metals and alloys,
In step F52, a chemical mechanical planarization process is used to polish the second polishing layer to the extent that the sacrificial mesa structure is not exposed to form a polishing surface;
In step F53, patterning the second polishing layer,
In step F54, a piezoelectric layer is formed on the polishing surface of the second polishing layer and the preliminary polishing surface of the insulating layer,
In step F55, an upper electrode is formed on the piezoelectric layer, and in step F6, the sacrificial mesa structure is etched to form vacancies, and the vacancies are located below the bulk acoustic wave resonance structure. ,
The second polishing layer located below the piezoelectric layer, above the vacancy, and between the polishing surface and the upper part of the entire mesa forms a bottom electrode layer of the bulk acoustic wave resonance structure, and the bulk The second polishing layer located below the acoustic wave resonance structure and between the upper part of the entire surface of the mesa and the holes forms a mass adjustment structure.
A method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure, wherein: After the step F52, the portions of the sacrificial mesa structure have a geometric configuration, the geometric configuration of the sacrificial mesa structure is related to a geometric configuration of the mass adjustment structure; Adjusting the geometric configuration of the mass tuning structure to enhance the Q factor of the bulk acoustic wave resonator by adjusting the geometric configuration of the sacrificial mesa structure;
The method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure according to claim 13. The substrate is a semiconductor substrate, and the sacrificial mesa structure is made of at least one material selected from a metal, an alloy, and an epitaxial structure;
The method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure according to claim 13. The substrate is a compound semiconductor substrate, and the step F1 includes the following steps F11 and F12.
In step F11, a sacrificial structure is formed on the substrate,
In step E12, the sacrificial structure is etched to form the sacrificial mesa structure.
The method for manufacturing a bulk acoustic wave resonance device with a mass adjusting structure according to claim 15, (1) the substrate is made of GaAs and the sacrificial structure is made of a GaAs layer; or (2) the substrate is made of InP and the sacrificial structure is made of an InGaAs layer.
The method for manufacturing a bulk acoustic wave resonance device with a mass adjustment structure according to claim 16. Further, a bottom etching stop layer is formed on the substrate, the sacrificial structure is formed on the bottom etching stop layer, (1) the bottom etching stop layer is made of InGaP, or (2) the bottom etching is performed. The stop layer is made of InP.
The manufacturing method of the bulk acoustic wave resonance apparatus with a mass adjustment structure of Claim 17 characterized by the above-mentioned.

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