CN115967365A - Resonator, manufacturing method thereof, filter and electronic equipment - Google Patents

Abstract

The invention proposes a resonator comprising: the piezoelectric ceramic chip comprises a substrate, a piezoelectric laminated structure located on the substrate and a cavity located between the piezoelectric laminated structure and the substrate, wherein the piezoelectric laminated structure at least comprises a bottom electrode layer, a piezoelectric layer and a top electrode layer which are sequentially laminated, the bottom electrode layer is provided with a concave area, and the bottom of the concave area is in contact with the surface of the substrate in the cavity. According to the scheme, the bottom electrode layer is partially recessed downwards to the surface of the substrate below the bottom electrode layer to form a recessed area, so that the film layer is supported, and the mechanical reliability and stability of the resonator are improved; at the same time, heat dissipation is accelerated through the recessed area, thereby reducing heat accumulation of the resonator. Furthermore, the effect of inhibiting the transverse wave is effectively improved through the shape change of the edge of the concave area, the matching of the maximum size of the opening of the concave area and the transverse wave length of the resonator, the filling of the heat-conducting medium material above the concave area and the like.

Description

Resonator, manufacturing method thereof, filter and electronic equipment

Technical Field

The invention belongs to the technical field of semiconductors, and particularly relates to a resonator, a manufacturing method of the resonator, a filter and electronic equipment.

Background

With the rapid development of mobile communication technology, the film bulk acoustic wave filter is widely applied to the fields of mobile phones, wi-Fi, mobile terminals and the like due to the advantages of high frequency band, large bandwidth, small volume, low insertion loss, high quality factor and the like. The main component in the Film Bulk Acoustic filter is a Film Bulk Acoustic Resonator (FBAR). Classic in the prior artThe FBAR structure of air gap type includes a substrate, a piezoelectric stack structure on the substrate, and a cavity between the substrate and the piezoelectric stack structure. The formation of the cavity causes the resonator to rely mainly on the edge of the bottom electrode layer in the piezoelectric stack structure for support, and the mechanical stability is poor. Taking a typical resonator size as an example, the unilateral length of the active region is about 50-150 μm, and the area of the active region is about 10000-15000 μm ² When the working frequency of the resonator is lower, the area of the effective area is increased to about 25000-35000 mu m ² (ii) a Alternatively, when the resonator operating frequency is high, especially in the high frequency range of 3.6-7G, the thickness of the electrodes will be greatly reduced. No matter the resonator works under the low frequency, the required area size increases, or works under the high frequency state, the required film thickness is reduced, the collapse of the piezoelectric laminated structure above the cavity central area is aggravated, the stability of the resonator is reduced, and the performance of the resonator is influenced.

Disclosure of Invention

To alleviate or solve the above-mentioned problems while improving device structure compatibility and high usability, the present invention proposes, in a first aspect, a resonator comprising:

the piezoelectric ceramic chip comprises a substrate, a piezoelectric laminated structure located on the substrate and a cavity located between the piezoelectric laminated structure and the substrate, wherein the piezoelectric laminated structure at least comprises a bottom electrode layer, a piezoelectric layer and a top electrode layer which are sequentially arranged in a laminated mode, the bottom electrode layer is provided with a concave area, and the bottom of the concave area is in contact with the surface of the substrate in the cavity.

According to the scheme, the bottom electrode layer is partially recessed downwards to the surface of the substrate below the bottom electrode layer and is in contact with the surface of the substrate to form a recessed area, so that the film layer is supported, and the mechanical reliability and stability of the resonator are improved. Meanwhile, the scheme also relieves the problem of heat accumulation in the resonator, and on one hand, the film layer above the depressed area does not generate resonance any more, so that heat is not generated, the heat cannot be accumulated in the central area of the resonator, and the distribution is more uniform; on the other hand, the concave area is in contact with the substrate, heat is transmitted to the substrate through the concave area, and compared with a conventional resonator structure, the heat dissipation path is increased, and the heat dissipation efficiency of the resonator is improved.

Preferably, the recessed region is located in the centre of the cavity. The distance between the central area of the conventional resonator and the substrate at the side edge of the cavity is far, the heat transmission distance is also far, and heat is usually accumulated in the central area, so that the concave area is arranged in the center of the cavity, the area with the most serious heat accumulation can not generate resonance, and the heat generation is effectively reduced. Meanwhile, the sunken area is positioned in the center of the cavity, so that a better supporting effect is achieved, and the mechanical stability of the resonator is effectively improved.

Preferably, the maximum dimension D of the opening of the depressed region is equal to an integral multiple of 1/4 of the wavelength of the transverse wave of the resonator. The characteristic can enable the transverse waves in any two opposite directions in the sunken area to meet to form mutual superposition of wave crests and wave troughs, and reduce the influence of the transverse waves on the resonator.

Further preferably, the maximum dimension D is not less than 10% of the maximum width of the resonator active area. This feature may enable the recess region to effectively support the resonator while reducing the heat dissipation distance and improving the heat transfer efficiency.

Preferably, the recessed region includes a gap with the piezoelectric layer above it, the gap including air or a heat conducting medium therein.

Further preferably, the heat conducting medium comprises at least one of silicon dioxide, silicon nitride, polysilicon, aluminum oxide, boron nitride, silicon carbide and metal materials or a combination of several of the same. By utilizing the technical characteristics, on one hand, the heat-conducting medium has better heat-conducting property, so that heat can be transmitted to the substrate more quickly, and the heat dissipation is accelerated; on the other hand, the propagation of the transverse wave can be effectively inhibited by utilizing the crystal orientation difference between the heat conducting medium and the piezoelectric layer.

Preferably, there is a non-smooth transition region between the sidewalls of the recessed region and the flat bottom electrode layer over the cavity. Further preferably, the side walls of the recessed region form an angle with the piezoelectric layer above the recessed region. The non-smooth transition region enables the edge of the concave region to form a part with abrupt appearance, and can effectively reflect transverse waves, so that the Q value of the resonator is improved.

Further, the film layer above the recessed region includes an uneven portion; the non-flat portion may be convex or concave or a combination thereof.

Preferably, the resonator has two or more recessed areas that are discrete from each other. The more the number of the depressed areas is, the better the mechanical stability of the resonator is, the higher the heat dissipation efficiency is, and the higher the performance of the resonator is.

Preferably, a portion of the bottom electrode layer located at the edge of the cavity and the other portion of the bottom electrode layer are electrically insulated from each other, and the bottom electrode layer is electrically connected to the outside of the resonator via the recess region. Parasitic oscillations can be effectively reduced.

Further, the bottom electrode layer has an opening between a portion of the bottom electrode layer at the edge of the cavity and the other portion of the bottom electrode layer.

Further, the inside of the substrate has an electrical connection portion connected to the outside, the electrical connection portion being electrically connected to the recessed region. Compare with the direct and outside electricity of bottom electrode layer in the prior art and connect, the bottom electrode layer has reduced parasitic capacitance through depressed area, substrate and outside electricity connection in this scheme.

Further preferably, a portion of the bottom electrode layer at the edge of the cavity is flat, and the piezoelectric layer above the bottom electrode layer is flat. Depending on this, there is no need to etch the bottom electrode layer, so that the piezoelectric layer can be kept flat, making the stress distribution of the resonator uniform.

Further, the cross section of the recess region in a direction parallel to the substrate is a circle, an ellipse, a regular polygon having angles each larger than 90 °, or an irregular polygon having angles each larger than 90 °.

Further, the cavity is located on the upper surface of the substrate or embedded in the substrate. The resonator of the present application is applicable to an above ground type cavity or an underground type cavity.

Preferably, the height of the cavity is less than 2 μm. Further preferably, the height of the cavity is 0.5-1.5 μm. By means of the technical scheme, the height of the cavity can be greatly reduced, so that the process cost is reduced, meanwhile, the heat dissipation path is shorter, and the heat dissipation effect is better.

The invention proposes, in a second aspect, a filter comprising a resonator as described above.

The invention proposes in a third aspect an electronic device comprising a resonator as described above.

The present invention in a fourth aspect proposes a method of manufacturing a resonator, comprising the steps of:

providing a substrate; forming a cavity on a substrate; and manufacturing a piezoelectric laminated structure covering the cavity on the substrate, wherein the piezoelectric laminated structure at least comprises a bottom electrode layer, a piezoelectric layer and a top electrode layer which are sequentially laminated, the bottom electrode layer is provided with a concave area, and the bottom of the concave area is in contact with the surface of the substrate in the cavity.

Further, in the manufacturing method, a gap is included between the recessed area and the piezoelectric layer above the recessed area, the gap includes air or a heat conducting medium, and the heat conducting medium includes at least one or a combination of several of silicon dioxide, silicon nitride, polysilicon, aluminum oxide, boron nitride, silicon carbide and a metal material.

According to the resonator provided by the invention, the sunken area is arranged on the bottom electrode layer, and the bottom of the sunken area is in contact with the surface of the substrate in the cavity, so that a film layer of the resonator is supported, and the mechanical reliability of a large resonator or a high-frequency resonator is improved; meanwhile, heat generated by the resonator is reduced through the concave region, heat in the effective region of the resonator is efficiently taken away, and the Long-Term operable service Life (LTOL) of the resonator is prolonged.

Drawings

The accompanying drawings assist in a further understanding of the present application. For convenience of description, only portions related to the related invention are shown in the drawings.

FIG. 1 is a cross-sectional view of a resonator according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a heat transfer path of a conventional resonator in the prior art;

FIG. 3 is a corresponding thermodynamic diagram of the resonator shown in FIG. 2;

FIG. 4 is a schematic diagram of a heat transfer path of a resonator according to another embodiment of the invention;

FIG. 5 is a corresponding thermodynamic diagram of the resonator shown in FIG. 4;

FIG. 6 is an enlarged partial view of the recessed area of the resonator shown in FIG. 1;

FIG. 7 is a cross-sectional view of a resonator according to another embodiment of the invention;

FIG. 8 is a cross-sectional view of a resonator according to another embodiment of the invention;

figure 9 is a cross-sectional view of a resonator according to another embodiment of the present invention;

FIG. 10 is a top view of a resonator according to another embodiment of the invention;

figure 11 is a cross-sectional view of a resonator according to another embodiment of the present invention;

FIG. 12 is a top view of a resonator according to another embodiment of the invention;

FIG. 13 is a cross-sectional view of a resonator according to another embodiment of the invention;

figure 14 is a cross-sectional view of a resonator according to another embodiment of the present invention;

FIG. 15 is a top view of the resonator shown in FIG. 1;

figure 16 is a cross-sectional view of a resonator according to another embodiment of the present invention;

FIGS. 17a-17g are schematic diagrams illustrating a process for fabricating a resonator according to another embodiment of the present invention;

fig. 18 is a cross-sectional view of a resonator according to another embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

Because components of embodiments can be positioned in a number of different orientations, the directional terminology, such as "top," "bottom," "left," "right," "up," "down," etc., is used with reference to the orientation of the figures to describe some embodiments. It is to be understood that the directional terminology is used for purposes of illustration and is in no way limiting. Other embodiments may be utilized and logical changes may be made without departing from the scope of the present invention.

Fig. 1 isbase:Sub>A cross-sectional view ofbase:Sub>A resonator 100 according to an embodiment of the invention, and fig. 15 isbase:Sub>A top view of the resonator 100, wherein the cross-section refers tobase:Sub>A plane perpendicular tobase:Sub>A resonator substrate and passing through two non-adjacent sides ofbase:Sub>A recess region, specifically, reference may be made tobase:Sub>A-base:Sub>A' cross-section in fig. 15, and the top view direction refers tobase:Sub>A top view direction of the resonator when the substrate is taken asbase:Sub>A bottom plane. Referring to fig. 1, a resonator 100 includes a substrate 101, a piezoelectric stack structure on the substrate 101, and a cavity 102 between the piezoelectric stack structure and the substrate 101, the piezoelectric stack structure including at least a bottom electrode layer 103, a piezoelectric layer 104, and a top electrode layer 105, which are sequentially stacked, the bottom electrode layer 103 having a recessed region 106, a bottom of the recessed region 106 being in surface contact with the substrate 101 in the cavity 102. The recessed region 106 provides an effective support for the film layers of the resonator, resulting in an improved mechanical stability of the resonator.

At the same time, the recessed region 106 can also alleviate the heat dissipation problem of the resonator. Fig. 2 is a schematic diagram of a heat transfer path of a resonator 100 'in the prior art, and fig. 3 is a corresponding thermodynamic diagram of the resonator 100', where numbers in the thermodynamic diagram represent temperature values. The common resonator 100 'comprises a substrate 101'; a bottom electrode layer 103', a piezoelectric layer 104', and a top electrode layer 105' on the substrate 101', the piezoelectric layer 104' being located between the bottom electrode layer 103' and the top electrode layer 105 '; a cavity 102' is arranged between the bottom electrode layer 103' and the substrate 101'; as shown by arrows in fig. 2, since air is a poor thermal conductor, in the conventional resonator, heat is mainly transferred to a portion of the substrate near the resonator through the electrodes and the piezoelectric layer, and the portion of the substrate transfers heat to the entire substrate and then transfers the heat to the outside. The distance between the central area of the resonator and the substrate at the side of the cavity is relatively long, that is, the distance for heat transmission is relatively long, and heat cannot be conducted out in time, so that heat accumulation can occur in the central area a of the resonator, as shown in fig. 3, the central area a of the resonator is overheated, which easily causes frequency drift of the resonator, or causes and accelerates aging of the piezoelectric laminated structure, thereby affecting the performance of the resonator. Fig. 4 is a schematic diagram of a heat transfer path of the resonator 100, and fig. 5 is a schematic diagram of the resonator 100, in which numbers indicate temperature values. As shown in fig. 4, the bottom electrode layer of the resonator 100 has a recessed region 106 recessed downward, which is located in the central region of the cavity 102, and the film layer above the recessed region 106 no longer generates resonance, thereby reducing heat generation; meanwhile, the concave area 106 is in contact with the substrate 101, heat is transmitted from the concave area 106 to the substrate, a heat dissipation path is increased, and the heat dissipation capacity of the resonator is improved. Comparing fig. 3 and 5, the operating temperature range of the resonator 100' is approximately 313K-343K, the highest temperature occurs in the central region of the resonator, and the temperature distribution gradually decreases outward around the central region of the resonator; the operating temperature range of the resonator 100 is approximately 298K-313K, and compared to the resonator 100', the central region of the resonator has the lowest heat, and the highest temperature occurs between the outer edge of the concave region and the outer edge of the resonator, and is distributed annularly. Therefore, the overall heat of the resonator is greatly reduced, the heat distribution is more uniform, and the long-term working performance of the resonator is greatly improved.

In another embodiment, as shown in FIG. 1, the maximum dimension D of the opening of the depressed region is set equal to an integral multiple of 1/4 of the wavelength of the transverse wave of the resonator. At this time, the cross section of the recessed region in the direction parallel to the substrate is preferably in an axisymmetric pattern, so that at the center of the recessed region, the transverse waves in any two opposite directions meet to form a peak and a trough which are mutually superposed, the vibration of the transverse waves is weakened or completely offset, and the effect of suppressing the transverse waves is achieved. It is further preferred that the cross-section of the recessed region in a direction parallel to the substrate is circular, while the active region of the resonator is preferably circular. The maximum dimension D is defined as the distance between the two points that are farthest apart in the cross-section of the opening of the recessed region 106. When the opening of the depressed region is circular in a plan view, the maximum dimension D is a diameter of the circular shape; when the opening of the recessed area is polygonal, the maximum dimension D is the maximum caliber dimension of the polygonal shape, i.e. the maximum distance between any two points on the edge of the opening.

In another particular embodiment, as shown in FIG. 1, the maximum dimension D is no less than 10% of the maximum width of the resonator. Since the larger the maximum dimension D, the better the supporting effect on the resonator, and at the same time, the larger the depressed area is as a transmission path, the smaller the heat dissipation distance of the hottest area of the resonator is, and the higher the heat transmission efficiency is. Therefore, the maximum dimension D of the opening of the depressed region is set to not less than 10% of the maximum width of the resonator in this direction in the present embodiment.

In another embodiment, as shown in fig. 1, the recessed region 106 and the overlying piezoelectric layer 104 include a gap 107 therebetween, and the gap 107 may include air or a heat conducting medium with better heat conductivity, such as at least one or a combination of silicon dioxide, silicon nitride, poly silicon (Poly), aluminum oxide, boron nitride, silicon carbide, and metal. When a heat-conducting medium with better heat conductivity is filled, heat can be more quickly transmitted into the substrate 101 through the heat-conducting medium, and heat dissipation is accelerated; and meanwhile, the heat-conducting medium can enhance the supporting effect. In addition, when the gap 107 is filled with a thermally conductive medium such as silicon dioxide, polysilicon, or metal, it does not have a crystal orientation close to the piezoelectric layer 104 (e.g., alN); alternatively, when AlN is filled in the gap 107, the filled AlN has no or poor crystal orientation, and is different from highly oriented AlN in the active region, and the effect of suppressing the propagation of the transverse wave can be achieved. Herein, the active area is generally defined in the art as an overlapping area of the top electrode layer, the piezoelectric layer, the bottom electrode layer and the cavity, and other areas except the active area are inactive areas.

In a specific embodiment, a non-smooth transition region is formed between the side wall of the recess region and the flat bottom electrode layer above the cavity. Fig. 6 is a partially enlarged view of the recessed region 106 of the resonator 100 shown in fig. 1, in this embodiment, an angle is formed between the sidewall of the recessed region 106 and the piezoelectric layer 104 above the recessed region 106, so that a non-smooth transition region is formed between the sidewall of the recessed region 106 and the flat bottom electrode layer 103 above the cavity 102. At this time, the concave region 106 forms a shape mutation at a position shown by an arrow, which can effectively reflect the transverse wave, wherein a part of the reflected transverse wave is converted into the longitudinal wave, and a part of the reflected transverse wave is trapped in the resonator, thereby avoiding the attenuation of the Q value caused by the energy leakage of the transverse wave at the edge of the effective region, and improving the performance of the device. It will be appreciated that in other embodiments, the non-smooth transition region may be formed in a different shape.

In another embodiment, the film over the recessed region includes an uneven portion; specifically, the non-flat portion may be convex upward, concave downward, or a combination thereof. The heat-conducting medium can be filled above the concave area, and the material, the volume, the filling times and the like of the filled heat-conducting medium can be set according to actual needs, so that the corresponding film layer above the concave area can also be formed with an uneven part and present different appearances. Fig. 7-9 are cross-sectional views of resonators having different topographies of the non-flat portions, the overall structure of which is similar to that of the resonator 100, except that the film layer above the recessed region includes the non-flat portions, specifically, as shown in fig. 7, the piezoelectric layer 104a and the top electrode layer 105a above the recessed region 106, respectively, include the non-flat portions having an upward convex shape; as shown in fig. 8, the corresponding piezoelectric layer 104b and top electrode layer 105b above the recess region 106 include an uneven portion having a concave shape downward; as shown in fig. 9, due to the provision of the sacrificial layer, the corresponding piezoelectric layer 104c and the top electrode layer 105c above the recess region 106 form a shape including both a structure of an upper convex shape and a lower concave shape, such as a wavy uneven portion.

In another embodiment, the resonator has two or more recessed regions that are discrete from one another. Fig. 10 is a top view of the resonator 200, and fig. 11 is a cross-sectional view of the resonator 200, wherein the cross-section refers to a plane perpendicular to the resonator substrate and passing through two non-adjacent sides of the recess region, and specifically, can refer to a B-B' cross-section in fig. 10, and the top view direction refers to the top view direction of the resonator when the substrate is taken as the bottom plane. As shown in fig. 10, similar to the resonator 100, the resonator 200 includes a substrate 201, a piezoelectric stack structure on the substrate 201, and a cavity 202 between the piezoelectric stack structure and the substrate 201, the piezoelectric stack structure includes at least a bottom electrode layer 203, a piezoelectric layer 204, and a top electrode layer 205, which are sequentially stacked, and a first gap 2071 and a second gap 2072 are below the piezoelectric layer 204. The difference from the resonator 100 is that the bottom electrode layer 203 has two recessed regions, i.e., a first recessed region 2061 and a second recessed region 2062. Fig. 12 is a top view of a resonator 200' in another embodiment, the top view direction being the top view direction of the resonator when the substrate is the bottom plane. As shown in fig. 12, the resonator 200 'includes a bottom electrode layer 203', a piezoelectric layer 204', and a top electrode layer 205' similar to the resonator 200, except that the bottom electrode layer 203 'has 3 recess regions, i.e., a first recess region 2061', a second recess region 2062', and a third recess region 2063'. The greater the number of recessed regions, the better the mechanical stability of the resonator, the higher the heat dissipation efficiency, and the higher the performance of the resonator.

In another embodiment, the portion of the bottom electrode layer at the edge of the cavity is electrically insulated from the other portion of the bottom electrode layer, and the bottom electrode layer is electrically connected to the outside of the resonator via the recessed region. In the prior art, parasitic capacitance is formed between the external connection part of the top electrode layer and the bottom electrode layer, and the performance of the resonator is influenced; meanwhile, a step is formed at the edge of the bottom electrode layer, the piezoelectric layer growing above the step is poor in orientation, parasitic oscillation is generated, the parasitic oscillation influences the resonance of an effective area, and finally the performance of the resonator is deteriorated. If the bottom electrode layer corresponding to the lower part of the external connection part of the top electrode layer is retracted into the cavity, the generation of parasitic oscillation can be reduced, but the supporting capacity of the resonator is greatly reduced, the collapse of the resonator is accelerated, and the stability of the resonator is greatly influenced. In this embodiment, the portion of the bottom electrode layer located at the edge of the cavity is electrically disconnected from the outside, and the recessed region is used to electrically connect the outside of the resonator, thereby alleviating the problems in the prior art. Specifically, FIG. 13 is a cross-sectional view of a resonator 300 in an embodiment, where cross-section refers to a plane perpendicular to the resonator substrate and passing through two non-adjacent sides of the recessed region. Referring to fig. 13, similar to the resonator 100, the resonator 300 includes a substrate 301, a piezoelectric stack structure on the substrate 301, and a cavity 302 between the piezoelectric stack structure and the substrate 301, the piezoelectric stack structure includes at least a bottom electrode layer 303, a piezoelectric layer 304, and a top electrode layer 305 stacked in sequence, the bottom electrode layer 303 has a recessed region 306, the bottom of the recessed region 306 is in surface contact with the substrate 301 in the cavity 302, and a gap 307 is included between the recessed region 306 and the piezoelectric layer 304 above the recessed region 306. The difference with respect to the resonator 100 mainly consists in that the bottom electrode layer 303 is provided with an opening 309 at the edge of the cavity 302, in the position shown by the circle in the figure, so that it is disconnected from the surroundings, the opening 309 being located inside the cavity 302. The substrate 301 has an electrical connection portion 308 connected to the outside inside thereof, and the electrical connection portion 308 is electrically connected to the recessed region 306. The bottom electrode layer 303 is electrically connected to the outside after being connected to the electrical connection portion 308 through the recessed region 306, so that the parasitic capacitance between the external connection portion of the top electrode layer and the bottom electrode layer is reduced.

Figure 14 is a cross-sectional view of a resonator 300' in another preferred embodiment, where cross-section refers to a plane perpendicular to the resonator substrate and passing through two non-adjacent sides of the recessed region. Referring to fig. 14, compared with the resonator 300, in this embodiment, the portion of the bottom electrode layer 303' located at the edge of the cavity 302 and the portion of the bottom electrode layer 303' located at the edge of the cavity are not etched, and thus the portion of the piezoelectric layer 304' above the bottom electrode layer 303' is also kept flat, so that the stress distribution of the resonator 300' is uniform.

The shape of the concave area is not limited, and the length-width ratio and the like of the concave area can be adjusted according to needs. In a specific embodiment, the cross-section of the recessed region in a direction parallel to the substrate is circular, elliptical, a regular polygon with angles greater than 90 ° each, or an irregular polygon with angles greater than 90 ° each. Referring to fig. 15, in the present embodiment, the opening cross-sectional shape of the depressed region 106 is set to be an irregular pentagon.

The relative position of the cavity and the substrate is not limited, the cavity can be positioned on the upper surface of the substrate or embedded in the substrate, namely an overground cavity or an underground cavity, and the film layer of the resonator can be supported, so that the effects of enhancing the mechanical stability of the resonator, enhancing the heat dissipation, inhibiting transverse waves and the like are achieved. In the resonator 100 shown in fig. 1, a surface of a substrate 101 is etched to embed a cavity 102 in the substrate 101, thereby forming a subsurface cavity. Figure 16 is a cross-sectional view of a resonator 400 in another embodiment, where the cross-section refers to a plane perpendicular to the resonator substrate and passing through two non-adjacent sides of the recessed region. Referring to fig. 16, similar to the resonator 100, the resonator 400 includes a substrate 401, a piezoelectric stack structure on the substrate 401, and a cavity 402 between the piezoelectric stack structure and the substrate 401, the piezoelectric stack structure includes at least a bottom electrode layer 403, a piezoelectric layer 404, and a top electrode layer 405 stacked in this order, the bottom electrode layer 403 has a recessed region 406, the bottom of the recessed region 406 is in contact with the surface of the substrate 401 in the cavity 402, and a gap 407 is included between the recessed region 406 and the piezoelectric layer 404 thereabove. The difference from the resonator 100 mainly includes that the cavity 402 of the resonator 400 is located on the upper surface of the substrate 401 in this embodiment, forming a ground type cavity 402. The overground cavity 402 is formed without etching the substrate 401, and both sides are supported by the bottom electrode layer 403, and the central region of the bottom electrode layer 403 is recessed downward to be in contact with the substrate 401, so that a recessed region 406 is formed.

In another embodiment, because the depressed area with the bottom electrode layer in the middle of the resonator is used for supporting, the supporting effect of the cavity is enhanced, and the problem that the central area of the resonator is adhered to the substrate after being collapsed is not generated, so that compared with the cavity with the general height of 2-3 μm, the height of the cavity of the resonator in this embodiment can be less than 2 μm, preferably, the height range of the cavity is 0.5-1.5 μm, the filled sacrificial material is reduced, the process cost is further reduced, meanwhile, the cavity height is reduced, the heat dissipation path of the resonator is shortened, and the heat dissipation effect is further improved.

The present invention further provides a method of manufacturing a resonator, comprising: providing a substrate having a cavity formed therein; and manufacturing a piezoelectric laminated structure covering the cavity on the substrate, wherein the piezoelectric laminated structure at least comprises a bottom electrode layer, a piezoelectric layer and a top electrode layer which are sequentially laminated, the bottom electrode layer is provided with a concave area, and the bottom of the concave area is in contact with the surface of the substrate in the cavity. In a preferred embodiment, a gap is included between the recessed region and the piezoelectric layer above the recessed region, and the gap includes air or a heat conducting medium, and the heat conducting medium includes at least one of silicon dioxide, silicon nitride, polysilicon, aluminum oxide, boron nitride, silicon carbide, and a metal material or a combination of several materials.

Although the steps of the method are listed above in a certain order, it will be understood by those skilled in the art that the steps may be performed in an order different from the above, i.e. the steps may be performed in an opposite or side-by-side manner. The detailed description of each structural layer is described in the content of the device, and is not repeated here.

Fig. 17a to 17g are schematic diagrams illustrating a manufacturing process of the resonator 500 according to an embodiment of the invention, which specifically includes:

as shown in fig. 17a, a substrate 501 is provided, and the substrate 501 is etched to form a cavity 502; the material of the substrate 501 is preferably Si, sapphire, spinel, or the like;

as shown in fig. 17b, a sacrificial material is deposited on a substrate 501, the sacrificial material is patterned to form a first sacrificial layer 502a, and optionally, the first sacrificial layer 502a is subjected to CMP (chemical mechanical polishing) with its central region recessed downward to form a recessed region of a bottom electrode layer; a preferred material for the first sacrificial layer 502a is PSG (P-doped SiO) ₂ )；

As shown in fig. 17c, on the first sacrificial layer 502a, a bottom electrode layer 503 and a middle recessed area 506 are formed by sputtering, photolithography and etching processes, preferably molybdenum (Mo) is used as a material, and other optional materials are metal materials or alloy materials of gold (Au), tungsten (W), copper (Cu), nickel (Ni), titanium (Ti), niobium (Nb), silver (Ag), tantalum (Ta), cobalt (Co) or aluminum (Al);

as shown in fig. 17d, a second sacrificial layer 507a is deposited on the recessed region 506 in the middle, and optionally, the second sacrificial layer 507a is subjected to CMP (chemical mechanical polishing) to make the upper surface thereof flush with the upper surface of the bottom electrode layer 503; a preferable material of the second sacrificial layer 507a is PSG (P-doped SiO) ₂ )；

As shown in fig. 17e, a piezoelectric layer 504 is grown on the second sacrificial layer 507a and the bottom electrode layer 503, and the preferred material of the piezoelectric layer 504 is aluminum nitride (AlN), and can also be selected from zinc oxide (ZnO), zinc sulfide (ZnS), lithium tantalate (LiTaO) ₃ ) Cadmium sulfide (CdS), lead titanate (PbTiO) ₃ ) Lead zirconate titanate (Pb (Zr, ti) O) ₃ ) Etc.;

as shown in fig. 17f, a top electrode layer 505 is formed on the piezoelectric layer 504 through sputtering, photolithography and etching processes, the top electrode layer 505 is preferably made of molybdenum (Mo), and other optional materials are metal materials or alloy materials such as gold (Au), tungsten (W), copper (Cu), nickel (Ni), titanium (Ti), niobium (Nb), silver (Ag), tantalum (Ta), cobalt (Co) or aluminum (Al);

as shown in fig. 17g, the first sacrificial layer 502a and the second sacrificial layer 507a are released.

Fig. 18 is a cross-sectional view of a resonator 500 'according to another embodiment of the invention, which differs from the resonator 500 mainly in that the resonator 500' fills the gap 507b above the recess region with a heat-conducting medium, which may be silicon dioxide (SiO) as an option ₂ ) Silicon nitride (Si) ₃ N ₄ ) Polysilicon (Poly), alumina (Al) ₂ O ₃ ) Boron Nitride (BN), silicon carbide (SiC), or a material such as silver (Ag), copper (Cu), gold (Au), aluminum (Al), sodium (Na) having a higher thermal conductivity, or any combination thereof, and a resonator in which the gap is filled with a heat conductive medium is manufactured without releasing the heat conductive medium.

The bottom electrode layer of the resonator provided by the invention is provided with at least one sunken area which is contacted with the substrate, the sunken area can support the resonator film layer, the mechanical reliability and the stability of the resonator are improved, meanwhile, the heat generation of the resonator can be reduced, the heat dissipation is accelerated, the power tolerance level of the resonator is improved, and the structure is particularly suitable for designing high-power FBAR devices with higher power, such as 10w and above.

While this application has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the application as defined by the appended claims.

Claims (23)

1. A resonator, the resonator includes the substrate, lies in the piezoelectric stack structure on the substrate, and lie in the cavity pocket between piezoelectric stack structure and the substrate, the piezoelectric stack structure includes at least bottom electrode layer, piezoelectric layer and the top electrode layer that stacks gradually, characterized by that, the bottom electrode layer has the depressed area, the bottom of depressed area contacts with the surface of substrate in the cavity pocket.

2. The resonator of claim 1, wherein the recessed region is located in a center of the cavity.

3. The resonator of claim 1, wherein the maximum dimension D of the opening of the depressed region is equal to an integer multiple of 1/4 wavelength of the transverse wave of the resonator.

4. The resonator of claim 3, characterized in that the maximum dimension D is not less than 10% of the maximum width of the resonator active area.

5. The resonator of claim 1, comprising a gap between the recessed region and a piezoelectric layer above the recessed region, the gap comprising air or a thermally conductive medium therein.

6. The resonator of claim 5, wherein the thermally conductive medium comprises at least one or a combination of silicon dioxide, silicon nitride, polysilicon, aluminum oxide, boron nitride, silicon carbide, and a metallic material.

7. The resonator of claim 1, wherein the sidewalls of the recessed region and the planar bottom electrode layer over the cavity have a non-smooth transition region therebetween.

8. The resonator of claim 7, wherein a sidewall of the recessed region forms an angle with the piezoelectric layer above the recessed region.

9. The resonator of claim 1, wherein the film layer over the recessed region comprises a non-flat portion.

10. The resonator of claim 9, wherein the non-flat portion is convex upward, concave downward, or a combination thereof.

11. The resonator of claim 1, wherein the resonator has at least two of the recessed regions that are discrete from one another.

12. The resonator according to any of claims 1-11, characterized in that the part of the bottom electrode layer at the edge of the cavity is electrically insulated from other parts of the bottom electrode layer, and that the bottom electrode layer is electrically connected to the outside of the resonator via a recessed area.

13. The resonator of claim 12, wherein the bottom electrode layer has an opening between a portion of the bottom electrode layer at an edge of the cavity and another portion of the bottom electrode layer.

14. The resonator of claim 12, wherein the interior of the substrate has electrical connections to the exterior, the electrical connections electrically connecting with the recessed region.

15. The resonator of claim 12, wherein the portion of the bottom electrode layer at the edge of the cavity is flat and the piezoelectric layer over the bottom electrode layer is flat.

16. The resonator according to any of claims 1-11, characterized in that the cross section of the recessed area in a direction parallel to the substrate is circular, elliptical, a regular polygon with angles larger than 90 ° each, or an irregular polygon with angles larger than 90 ° each.

17. The resonator according to any of claims 1-11, characterized in that the cavity is located on the upper surface of the substrate or embedded inside the substrate.

18. The resonator according to any of claims 1-11, characterized in that the height of the cavity is less than 2 μm.

19. The resonator of claim 18, wherein the cavity has a height of 0.5-1.5 μm.

20. A filter comprising a resonator according to any of claims 1-19.

21. An electronic device characterized in that it comprises a resonator as claimed in any one of claims 1-19.

22. A method of manufacturing a resonator comprising the steps of:

providing a substrate;

forming a cavity on the substrate;

and manufacturing a piezoelectric laminated structure covering the cavity on the substrate, wherein the piezoelectric laminated structure at least comprises a bottom electrode layer, a piezoelectric layer and a top electrode layer which are sequentially laminated, and the piezoelectric laminated structure is characterized in that the bottom electrode layer is provided with a concave area, and the bottom of the concave area is contacted with the surface of the substrate in the cavity.

23. The method of manufacturing of claim 22, wherein the recessed region includes a gap with the piezoelectric layer above the recessed region, the gap including air or a heat conducting medium, the heat conducting medium including at least one or a combination of silicon dioxide, silicon nitride, polysilicon, aluminum oxide, boron nitride, silicon carbide, and a metal material.

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