CN216290854U - Resonator and filter - Google Patents

Abstract

The embodiment of the utility model discloses a resonator and a filter. The resonator comprises a substrate, wherein a first groove is arranged on a first surface of the substrate; a lower electrode disposed on the first surface of the substrate; wherein the lower electrode comprises an opening, and the depth of at least partial area of the opening along the thickness direction of the lower electrode is smaller than the thickness of the lower electrode; a filling layer filled in the opening; the piezoelectric layer is arranged on one side of the lower electrode, which is far away from the substrate; and the upper electrode is arranged on one side of the piezoelectric layer, which is far away from the substrate.

Description

Resonator and filter

Technical Field

The embodiment of the utility model relates to the technical field of semiconductors, in particular to a resonator and a filter.

Background

Resonators have been widely used in many fields. For example, in the field of wireless communications, resonators of Radio Frequency (RF) and microwave frequencies are used as filters to improve the reception and transmission of signals. With the demand for miniaturization and miniaturization of communication devices, resonators based on the piezoelectric effect have been proposed. In a resonator based on the piezoelectric effect, an acoustic resonance mode is generated in a piezoelectric material, in which an acoustic wave is converted into a radio wave.

Fig. 1 is a schematic structural diagram of a resonator in the prior art, and referring to fig. 1, in the prior art, the edge of a lower electrode 103 is usually required to be etched to form an acute angle of about 15 ° in the resonator based on the piezoelectric effect. However, the etching angle of the lower electrode 103 needs to be measured by a machine, the process control is inconvenient, the requirement on the etching process is strict in order to form an acute angle of about 15 °, and the slope position is easy to have etching by-products left, which is unfavorable for the growth of the piezoelectric layer 102.

SUMMERY OF THE UTILITY MODEL

The utility model provides a resonator and a filter, which are used for improving the film deposition quality of a piezoelectric layer and reducing the process difficulty of a lower electrode.

An embodiment of the present invention provides a resonator, including:

the device comprises a substrate, wherein a first groove is formed in a first surface of the substrate;

a lower electrode disposed on the first surface of the substrate; wherein the lower electrode comprises an opening, and the depth of at least partial area of the opening along the thickness direction of the lower electrode is smaller than the thickness of the lower electrode;

a filling layer filled in the opening;

the piezoelectric layer is arranged on one side of the lower electrode, which is far away from the substrate;

and the upper electrode is arranged on one side of the piezoelectric layer, which is far away from the substrate.

Optionally, the opening includes a first region and a second region, the second region being closer to the first groove than the first region;

the depth of the first region is equal to the thickness of the lower electrode, and the depth of the second region is smaller than the thickness of the lower electrode.

Optionally, the lower electrode further includes a second groove, and a depth of the second groove is less than or equal to a thickness of the lower electrode along a thickness direction of the lower electrode;

the filling layer is also filled in the second groove.

Optionally, a height difference between a surface of the filling layer away from the substrate and a surface of the lower electrode away from the substrate is less than or equal to 300A.

Optionally, the resonator further includes:

and the protruding structure is arranged on the surface of the lower electrode, which is far away from the substrate.

Optionally, the protruding structure is made of a high-impedance material.

Optionally, the filling layer is made of a high-impedance material.

Optionally, the resonator further includes:

the seed layer is arranged between the lower electrode and the substrate.

Optionally, the thickness of the lower electrode ranges from 1000-.

Optionally, a microstructure for reducing mechanical wave propagation in the horizontal direction is disposed on the upper electrode;

the microstructures include at least one of bridge structures, wing structures, raised structures, and recessed structures.

In a second aspect, an embodiment of the present invention further provides a filter, including at least one resonator according to any embodiment of the present invention.

According to the resonator provided by the embodiment of the utility model, the opening is formed in the lower electrode, and the filling layer is filled in the opening, so that the piezoelectric layer can be formed on the plane, the piezoelectric layer is ensured to have better film deposition quality, the lower electrode does not need to be etched to form an acute angle of about 15 degrees in the embodiment, the process difficulty is reduced, and the control is convenient.

Drawings

FIG. 1 is a schematic diagram of a prior art resonator structure;

FIG. 2 is a schematic diagram of a resonator provided by an embodiment of the present invention;

FIG. 3 is a schematic view of a lower electrode according to an embodiment of the present invention;

FIG. 4 is a schematic illustration of a layer of filler material provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of a fill layer provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of a piezoelectric layer and an upper electrode provided by an embodiment of the present invention;

FIG. 7 is a schematic diagram of yet another resonator provided by an embodiment of the present invention;

FIG. 8 is a schematic diagram of yet another resonator provided by an embodiment of the present invention;

FIG. 9 is a schematic diagram of yet another resonator provided by an embodiment of the present invention;

FIG. 10 is a schematic diagram of yet another resonator provided by an embodiment of the present invention;

fig. 11 is a schematic diagram of another resonator provided in an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the utility model and are not limiting of the utility model. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

An embodiment of the present invention provides a resonator, and fig. 2 is a schematic diagram of the resonator provided in the embodiment of the present invention, and referring to fig. 2, the resonator includes:

a substrate 10, a first surface of the substrate 10 being provided with a first groove 11;

a lower electrode 20 disposed on the first surface of the substrate 10; wherein, the lower electrode 20 comprises an opening 21, and the depth of at least a partial region of the opening 21 along the thickness direction of the lower electrode 20 is smaller than the thickness of the lower electrode 20;

a filling layer 30 filled in the opening;

a piezoelectric layer 40 disposed on a side of the lower electrode 20 away from the substrate;

and an upper electrode 50 disposed on a side of piezoelectric layer 40 remote from the substrate.

The vertical projection of the opening 21 on the substrate 10 may not overlap with the vertical projection of the first groove 11 on the substrate 10, or the vertical projection of the opening on the substrate 10 may partially overlap with the vertical projection of the first groove 11 on the substrate 10, which is not limited in this embodiment.

Fig. 3 is a schematic view of a lower electrode according to an embodiment of the present invention, and referring to fig. 3, a first groove 11 may be formed in a substrate 10 through a photolithography process, a sacrificial layer 12 may be filled in the first groove 11, and a material of the sacrificial layer 12 may include phosphosilicate glass (PSG), which schematically includes 8% of phosphorus and 92% of silicon dioxide. The shape of the first groove 11 may be set as desired, and for example, may be set as a groove having an inverted trapezoidal cross section as shown in fig. 3.

After the sacrificial layer 12 is formed, a lower electrode 20 may be formed on the first surface of the substrate 10. The material of the lower electrode 20 may include molybdenum Mo or tungsten W. When forming the lower electrode 20, a first material layer may be formed on the first surface of the substrate 10, a photoresist layer is disposed on the surface of the first material layer, the photoresist layer is subjected to photolithography, the first material layer is etched to form the opening 21, and finally the photoresist layer is removed. The etching may be dry etching or wet etching, and this embodiment is not particularly limited. In addition, the shape of the opening 21 is not particularly limited in this embodiment.

Fig. 4 is a schematic diagram of a filling material layer provided by an embodiment of the utility model, fig. 5 is a schematic diagram of a filling layer provided by an embodiment of the utility model, and referring to fig. 4 and fig. 5, after the lower electrode 20 is formed, the filling material layer 31 may be formed on a side of the lower electrode 20 away from the substrate 10, the filling material layer 31 may be thinned by a chemical mechanical polishing process to form the filling layer 30, and the filling layer 30 only fills the opening 21. The filling layer 30 may be made of a high impedance material to form an acoustic impedance mismatch structure at one end of the lower electrode 20, so as to reflect transverse waves, avoid leakage, and further improve the Q value. For example, the filling layer 30 may be made of a material having a resistance greater than that of the piezoelectric layer 40, such as phosphosilicate glass (PSG) or silicon dioxide (USG). The thickness of the layer 31 of filling material may furthermore be 4000A-20000A.

Fig. 6 is a schematic diagram of a piezoelectric layer and an upper electrode according to an embodiment of the present invention, and referring to fig. 2 and 6, after the filling layer 30 is formed, the piezoelectric layer 40 and the upper electrode 50 may be formed on the surface side of the lower electrode 20, and then the sacrificial layer 12 in the first recess 11 may be removed to form a cavity. The cavity is used for reflecting energy, so that energy loss is reduced, and the quality factor Q of the resonator is improved. The material of the upper electrode 50 may be molybdenum or tungsten.

The resonator that this embodiment provided is through setting up the opening at the bottom electrode, through pack the one deck filling layer in the opening for the piezoelectric layer can form on the plane, has guaranteed that the piezoelectric layer has better film deposition quality, and the bottom electrode need not the sculpture in this embodiment and forms the acute angle about 15, has reduced the technology degree of difficulty, the management and control of being convenient for.

Alternatively, referring to fig. 2, the opening 21 includes a first region 201 and a second region 202, the second region 202 being closer to the first groove 11 than the first region 201;

the depth of the first region 201 is equal to the thickness of the lower electrode 20, and the depth of the second region 202 is less than the thickness of the lower electrode 20 in the thickness direction of the lower electrode 20.

Specifically, by providing the second region 202 to retain a portion of the lower electrode 20, the rate of heat dissipation from the resonator can be increased. Further, when the opening 21 overlaps the first groove 11 in the vertical projection of the substrate 10, the overlapping area is a partial area of the second area 202 or the entire second area 202.

Fig. 7 is a schematic diagram of another resonator provided by the embodiment of the present invention, and optionally, referring to fig. 7, the lower electrode 20 further includes a second groove 22, and a depth of the second groove 22 is equal to a thickness of the lower electrode 20 along a thickness direction of the lower electrode 20;

the filling layer 30 is also filled in the second groove 22.

Specifically, the filling layer 30 is disposed in the second groove 22, so that the piezoelectric layer 40 is formed on a plane, and the piezoelectric layer 40 has high film forming quality. In addition, the second groove 22 may suppress a lateral mode, improving the quality factor of the resonator.

Optionally, a height difference between the surface of the filling layer 30 away from the substrate 10 and the surface of the lower electrode 20 away from the substrate 10 is less than or equal to 300A.

Specifically, because the filling layer 30 is formed by a chemical mechanical polishing process, the dimensional accuracy of the filling layer 30 is high, and the height difference between the filling layer 30 and the lower electrode 20 is set to be less than 300A, so that the surface of the lower electrode 20 is not damaged, the piezoelectric layer 40 can be formed on a smoother surface, and the piezoelectric layer 40 is ensured to have higher film deposition quality.

Fig. 8 is a schematic diagram of another resonator provided by the embodiment of the present invention, and optionally, referring to fig. 8, the resonator further includes a protruding structure 60, where the protruding structure 60 is disposed on a surface of the lower electrode 20 away from the substrate 10.

The bump structure 60 may be made of a material with high impedance, for example, the bump structure 60 may be made of a material with impedance larger than that of the piezoelectric layer 40, for example, the bump structure 60 may be made of a material such as non-etchable borosilicate glass NEBSG, carbon-doped oxide CDO, silicon carbide SiC or silicon dioxide SiO 2. The two ends of the raised structure 60 provide a mechanical discontinuity to allow control of the phase of the reflected mode and provide an overall beneficial suppression of the propagating eigenmodes in the resonator active region. In addition, the vertical projection of the protrusion structure 60 on the substrate 10 may or may not overlap with the first groove 11, and the embodiment is not particularly limited.

Fig. 9 is a schematic diagram of another resonator provided in an embodiment of the present invention, and optionally, referring to fig. 9, the resonator further includes:

a seed layer 80, the seed layer 80 being disposed between the lower electrode 20 and the substrate 10.

Specifically, the material of the seed layer 80 may be aluminum nitride or the like. The openings 21 and the second grooves 22 may penetrate the seed layer 80. For example, when the seed layer 80 and the lower electrode layer 20 are formed, the first material layer, the seed material layer, and the photoresist layer may be sequentially formed, the photoresist layer may be patterned, and then the first material layer and the seed material layer may be sequentially etched, so that the lower electrode 20 and the seed layer 80 may be sequentially formed.

Optionally, referring to fig. 9, the resonator further includes:

and the passivation layer 90 is arranged on the side of the upper electrode 50 far away from the substrate 10, and the vertical projection of the passivation layer 90 on the substrate 10 is coincident with the vertical projection of the upper electrode 50 on the substrate.

Specifically, the passivation layer 90 serves to protect the upper electrode 50 from corrosion or damage of the upper electrode 50. The vertical projection of the passivation layer 90 on the substrate 10 coincides with the vertical projection of the upper electrode 50 on the substrate, so that the passivation layer 90 can better protect the upper electrode 50, and the passivation layer 90 and the upper electrode 50 can be formed by using the same mask. For example, the formation process of the upper electrode 50 and the passivation layer 90 may include: a second material layer, a third material layer and a photoresist layer may be sequentially formed on the surface of the piezoelectric layer 30 away from the substrate 10, then the photoresist layer is patterned by using a mask, then the third material layer is etched to form a passivation layer 90, and then the second material layer is etched to form the upper electrode 50.

Optionally, the thickness of the bottom electrode ranges from 1000-. The specific thickness of the lower electrode may be set according to the depth of the opening, and the present embodiment is not particularly limited, and the thickness of the exemplary lower electrode may be 1500A, 2000A, 2500A, 3000A, or the like.

Fig. 10 is a schematic diagram of another resonator provided by the embodiment of the present invention, fig. 11 is a schematic diagram of another resonator provided by the embodiment of the present invention, and optionally, referring to fig. 10 and fig. 11, a microstructure 51 for reducing mechanical wave propagation in the horizontal direction is disposed on the upper electrode 50; the microstructures 51 include at least one of a bridge structure, a wing structure, a convex structure, and a concave structure.

Specifically, the microstructure 51 may include one or more of a bridge structure shown in fig. 10, an airfoil structure, a convex structure and a concave structure shown in fig. 11, and the embodiment is not particularly limited.

The embodiment of the utility model also provides a filter which comprises at least one resonator in any embodiment of the utility model.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements, substitutions and combinations, as will now become apparent to those skilled in the art, without departing from the scope of the utility model. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. A resonator, comprising:

the device comprises a substrate, wherein a first groove is formed in a first surface of the substrate;

a lower electrode disposed on the first surface of the substrate; wherein the lower electrode comprises an opening, and the depth of at least partial area of the opening along the thickness direction of the lower electrode is smaller than the thickness of the lower electrode;

a filling layer filled in the opening;

the piezoelectric layer is arranged on one side of the lower electrode, which is far away from the substrate;

and the upper electrode is arranged on one side of the piezoelectric layer, which is far away from the substrate.

2. The resonator of claim 1, wherein:

the opening comprises a first area and a second area, and the second area is closer to the first groove relative to the first area;

the depth of the first region is equal to the thickness of the lower electrode, and the depth of the second region is smaller than the thickness of the lower electrode.

3. The resonator of claim 1, wherein:

the lower electrode further comprises a second groove, and the depth of the second groove is smaller than or equal to the thickness of the lower electrode along the thickness direction of the lower electrode;

the filling layer is also filled in the second groove.

4. The resonator according to any of claims 1-3, characterized in that:

the height difference between the surface of the filling layer far away from the substrate and the surface of the lower electrode far away from the substrate is less than or equal to 300A.

5. The resonator of any of claims 1-3, further comprising:

and the protruding structure is arranged on the surface of the lower electrode, which is far away from the substrate.

6. The resonator of claim 5, wherein:

the convex structure is made of high-impedance material;

the filling layer is made of high-impedance materials.

7. The resonator of any of claims 1-3, further comprising:

the seed layer is arranged between the lower electrode and the substrate.

8. The resonator according to any of claims 1-3, characterized in that:

the thickness range of the lower electrode is 1000-4000A.

9. The resonator according to any of claims 1-3, characterized in that:

the upper electrode is provided with a microstructure for reducing the propagation of mechanical waves in the horizontal direction;

the microstructures include at least one of bridge structures, wing structures, raised structures, and recessed structures.

10. A filter, characterized in that it comprises at least one resonator according to any one of claims 1-9.

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