CN113285689B

CN113285689B - Quartz crystal resonator, method for forming same, and electronic device

Info

Publication number: CN113285689B
Application number: CN202110245408.5A
Authority: CN
Inventors: 张孟伦; 庞慰
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2023-01-31
Anticipated expiration: 2041-03-05
Also published as: CN113285689A

Abstract

The invention discloses a quartz crystal resonator and an electronic device with the same, which can meet the requirements of high resonance frequency and external stress resistance, mechanical impact resistance, stability and reliability. The quartz crystal resonator comprises a substrate and a main functional structure which are vertically overlapped, wherein the main functional structure comprises a quartz piezoelectric layer, a first electrode, a second electrode and a mechanical reinforcing structure, the substrate and the main functional structure are connected through bonding, the top view projection of a contact area where the mechanical reinforcing structure is contacted with the quartz piezoelectric layer and the top view projection of a bonding area where the substrate is bonded with the main functional structure are overlapped. The invention also discloses a forming method of the quartz crystal resonator.

Description

Quartz crystal resonator, method for forming same, and electronic device

Technical Field

The invention relates to the technical field of resonators, in particular to a quartz crystal resonator, a forming method thereof and electronic equipment.

Background

Quartz Crystal bulk acoustic resonators (Quartz Crystal resonators) are electronic components that work by using the piezoelectric effect of Quartz crystals, are key elements in electronic devices such as oscillators, filters and the like, and have outstanding advantages and wide application in the aspects of frequency stabilization, frequency selection and precise timing. The current trend requires quartz resonators with higher resonance frequencies (e.g., greater than 40 MHz) and better stability and reliability against mechanical shock. On one hand, a thinner quartz resonance area is difficult to form by only etching the quartz substrate in the traditional mode, and the higher target resonance frequency is reached, and the quartz film manufactured by the MEMS process is more favorable for manufacturing the high-frequency quartz resonator. On the other hand, when the quartz thin film is thin, external stress (e.g., stress from the substrate) is more easily transmitted to the quartz thin film resonance region to affect the frequency stability of the resonator; meanwhile, when the quartz thin film is thin, the resonator is more susceptible to mechanical shock and environmental vibration, and its reliability is further deteriorated as compared with a low frequency quartz resonator.

It is highly desirable to find a structural design and a manufacturing method that can satisfy the requirements of high resonant frequency of the quartz resonator on the one hand and external stress resistance, mechanical shock resistance, stability and reliability on the other hand.

Disclosure of Invention

In view of the above, the present invention provides a quartz crystal resonator, a method for manufacturing the same, and an electronic device including the same, which can satisfy both the requirement of the quartz crystal resonator for high resonant frequency and the requirement of external stress resistance, mechanical shock resistance stability, and reliability.

The invention provides a quartz crystal resonator, which comprises a substrate and a main functional structure which are vertically stacked, wherein the main functional structure comprises a quartz piezoelectric layer, a first electrode, a second electrode and a mechanical reinforcing structure, the substrate and the main functional structure are connected through bonding, and the top projection of a contact area of the mechanical reinforcing structure and the quartz piezoelectric layer, which are in contact, and the top projection of a bonding area of the substrate and the main functional structure, which are bonded, are overlapped.

Optionally, the mechanical reinforcing structure comprises a support layer and an upper substrate layer.

Optionally, the mechanical reinforcing structure is a cap-like reinforcing structure.

Optionally, the substrate is provided with a cavity in proximity to the functional structure of the body.

Optionally, a package structure is also included.

Optionally, the mechanical enhancement structure is located on the quartz piezoelectric layer, and the substrate is bonded with the quartz piezoelectric layer.

Optionally, the mechanical enhancement structure is located below the quartz piezoelectric layer, and the substrate is bonded to the mechanical enhancement structure.

Optionally, the package structure further comprises an electrode leading-out structure leading out through the substrate or the package structure.

The second aspect of the present invention provides a method for forming a quartz crystal resonator, comprising: providing a quartz piezoelectric layer; forming a first electrode over the quartz piezoelectric layer; forming a sacrificial layer over the first electrode; depositing a support layer over the sacrificial layer and grinding the support layer flat; flipping the current semiconductor structure and then bonding to the upper substrate layer; thinning the quartz piezoelectric layer; forming a second electrode over the quartz piezoelectric layer; removing the sacrificial layer; bonding the current semiconductor structure onto a substrate after being turned over, wherein the quartz piezoelectric layer is mutually contacted with the substrate; and forming an encapsulation structure above the substrate, wherein the top projection of the bonding area of the quartz piezoelectric layer and the substrate and the top projection of the contact area of the support layer and the quartz piezoelectric layer are overlapped.

A third aspect of the present invention provides a method of forming a quartz crystal resonator, comprising: providing a quartz piezoelectric layer; forming a first electrode over the quartz piezoelectric layer; forming a sacrificial layer over the first electrode; depositing a support layer over the sacrificial layer and grinding the support layer flat; flipping the current semiconductor structure and then bonding to the upper substrate layer; thinning the quartz piezoelectric layer; forming a second electrode over the quartz piezoelectric layer; removing the sacrificial layer; bonding the current semiconductor structure directly onto a substrate, wherein the upper substrate layer and the substrate are in contact with each other; and forming an encapsulation structure above the substrate, wherein the top projection of the bonding region of the upper substrate layer and the substrate and the top projection of the contact region of the support layer and the quartz piezoelectric layer are overlapped.

A fourth aspect of the present invention provides a method of forming a quartz crystal resonator, comprising: providing a quartz piezoelectric layer; forming a first electrode over the quartz piezoelectric layer; flipping the current semiconductor structure and then bonding to the cap-shaped reinforcing structure; thinning the quartz piezoelectric layer; forming a second electrode over the quartz piezoelectric layer; bonding the current semiconductor structure onto a substrate after being turned over, wherein the quartz piezoelectric layer is mutually contacted with the substrate; and forming an encapsulation structure above the substrate, wherein the top projection of the bonding area of the quartz piezoelectric layer and the substrate and the top projection of the bonding area of the cover-shaped reinforcing structure and the quartz piezoelectric layer are overlapped.

The fifth aspect of the present invention provides a method for forming a quartz crystal resonator, including: providing a quartz piezoelectric layer; forming a first electrode over the quartz piezoelectric layer; flipping the current semiconductor structure and then bonding to the cap-shaped reinforcing structure; thinning the quartz piezoelectric layer; forming a second electrode over the quartz piezoelectric layer; bonding the current semiconductor structure directly onto a substrate, wherein the cap-shaped reinforcing structure and the substrate are in contact with each other; and forming an encapsulation structure above the substrate, wherein the top projection of the bonding area of the cover-shaped reinforcing structure and the substrate and the top projection of the bonding area of the cover-shaped reinforcing structure and the quartz piezoelectric layer are overlapped.

A sixth aspect of the invention provides an electronic device comprising any of the Xiang Danying crystal resonators of the invention.

According to the technical scheme, the embodiment of the invention discloses a quartz crystal resonator manufactured by using an MEMS (micro electro mechanical System) process, a quartz wafer is integrally thinned by using the MEMS processes such as lapping, chemical mechanical polishing, dry etching and the like, so that the quartz resonance area reaches the target thickness (namely the target frequency), meanwhile, a structure with stronger mechanical stability is configured in a non-resonance area (particularly the connection bonding position with a substrate), a device is insensitive to external stress, mechanical impact and environmental vibration, the reliability and the frequency stability are higher, the mass and low-cost manufacturing can be realized, and the manufactured device has high precision and good consistency.

Drawings

For purposes of illustration and not limitation, the present invention will now be described in accordance with its preferred embodiments, particularly with reference to the accompanying drawings, wherein:

fig. 1a to 1n are schematic diagrams illustrating a method for forming a quartz crystal resonator according to a first embodiment of the present invention;

FIGS. 2a to 2e are schematic diagrams illustrating the manufacturing process of the electrode lead-out of the quartz crystal resonator according to the first embodiment of the present invention;

FIGS. 3a to 3b are schematic diagrams illustrating a method for forming a quartz crystal resonator according to a second embodiment of the present invention;

FIGS. 4a to 4d are schematic diagrams illustrating the manufacturing process of the electrode lead-out of the quartz crystal resonator according to the second embodiment of the present invention;

FIGS. 5a to 5j are schematic diagrams illustrating a method for forming a quartz-crystal resonator according to a third embodiment of the present invention;

FIGS. 6a to 6c are schematic diagrams illustrating a process of manufacturing an electrode lead-out of a quartz crystal resonator according to a third embodiment of the present invention;

fig. 7a to 7b are schematic diagrams illustrating a method for forming a quartz-crystal resonator according to a fourth embodiment of the invention.

Detailed Description

The quartz crystal resonator comprises a substrate and a main functional structure which are vertically overlapped, wherein the main functional structure comprises a quartz piezoelectric layer, a first electrode, a second electrode and a mechanical reinforcing structure, and the substrate and the main functional structure are connected through bonding, wherein the top view projection of a contact area where the mechanical reinforcing structure is contacted with the quartz piezoelectric layer and the top view projection of a bonding area where the substrate is bonded with the main functional structure are overlapped.

Because the quartz crystal resonator of the embodiment of the invention adopts the special design that two overlooking projections are overlapped, the external stress or mechanical impact on the quartz crystal resonator can be smoothly transmitted to the mechanical reinforcing structure, so that most of the external stress or mechanical impact can be effectively distributed by the mechanical reinforcing structure, the stability of the quartz piezoelectric layer is protected, and the reliability of the device is further improved. In addition, the substrate is provided with a cavity at a position close to the main body functional structure, so that when external impact or stress occurs, a displacement space of the main body function can be provided, and the main body functional structure and other structures are prevented from being damaged due to mechanical impact.

The details of the parts marked in the figures are described below.

101: an upper substrate layer. For carrying and enclosing the acoustic device, the material can typically be selected from single crystal silicon, quartz, gallium arsenide, or sapphire, among others.

102: the material of the cap-shaped reinforcing structure can be silicon, glass or quartz.

103: an acoustic mirror, which is formed as a cavity embedded in the device, but any other acoustic mirror structure, such as a bragg reflector, is equally suitable.

104: the sacrificial layer can be made of silicon dioxide, doped silicon dioxide, polysilicon, amorphous silicon and the like.

105: and the supporting layer is made of a material different from that of the sacrificial layer.

107: the first electrode, the material of the first electrode can be: gold (Au), silver (Ag), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium Tungsten (TiW), aluminum (Al), titanium (Ti), osmium (Os), magnesium (Mg), germanium (Ge), copper (Cu), chromium (Cr), arsenic-doped gold, and the like.

109: a quartz piezoelectric layer.

111: the second electrode, the material of which may be the same as the first electrode 107. The material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or the compound of the above metals or the alloy thereof, etc. The material of the second electrode and the first electrode is generally the same, but may be different.

113: the first electrode extraction layer is made of high conductivity metal, such as molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or their composite or their alloy.

115/121: and the adhesion layer is used for tightly adhering. The material can be high-conductivity metal, and can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the metals or an alloy thereof. Non-metallic materials with strong adhesion may also be selected.

117: the substrate, the material is typically silicon.

118: a first through hole.

123: the package structure, material is typically silicon.

125: a second through hole and a second electrode lead-out layer.

Fig. 1a to 1n are schematic diagrams illustrating a method for forming a quartz crystal resonator according to a first embodiment of the present invention.

As shown in fig. 1a, a quartz piezoelectric layer 109 is provided;

as shown in fig. 1b, a first electrode 107 is formed on a quartz piezoelectric layer 109;

as shown in fig. 1c, a sacrificial layer 104 is formed over the first electrode 107;

as shown in fig. 1d, a support layer 105 is deposited over sacrificial layer 104;

as shown in fig. 1e, the support layer 105 is ground flat;

as shown in fig. 1f, the current semiconductor structure is flipped and then bonded to the upper substrate layer 101;

as shown in fig. 1g, the quartz piezoelectric layer 109 is thinned;

as shown in fig. 1h, a second electrode 111 is formed on the quartz piezoelectric layer 109;

as shown in fig. 1i, adhesion layer 115 is deposited and etched;

as shown in fig. 1j, the sacrificial layer 104 is removed, forming the acoustic mirror 103;

as shown in fig. 1k, a substrate 117 is prepared;

as shown in fig. 1l, the semiconductor structure shown in fig. 1j is turned over and bonded onto a substrate 117, wherein the quartz piezoelectric layer 109 and the substrate 117 are in contact with each other;

as shown in fig. 1m, a package structure 123 is prepared;

as shown in fig. 1n, package structure 123 is bonded to substrate 117 to achieve formation of package structure 123 over substrate 117.

As can be seen from the figure, in the quartz crystal resonator according to the first embodiment of the present invention, the top projection of the bonding region between the quartz piezoelectric layer 109 and the substrate 117 and the top projection of the contact region between the support layer 105 and the quartz piezoelectric layer 109 have an overlap.

The quartz crystal resonator according to the first embodiment of the present invention may further include an electrode lead-out structure led out through the substrate or the package structure.

Fig. 2a to 2e are schematic diagrams of an electrode lead-out manufacturing process of a quartz crystal resonator according to a first embodiment of the present invention, in which an electrode lead-out structure is led out through a substrate.

The semiconductor structure shown in fig. 2a is similar to the semiconductor structure shown in fig. 1 h;

as shown in fig. 2b, on the basis of the semiconductor structure shown in fig. 2a, the sacrifice layer 104 is removed to obtain the acoustic mirror 103, and the first electrode lead-out layer 113 is produced;

as shown in fig. 2c, the semiconductor structure shown in fig. 2b is flipped over and then bonded onto a substrate 117;

as shown in fig. 2d, a package structure 123 is formed over the substrate 117;

as shown in fig. 2e, a second via hole and a second electrode lead-out layer 125 are formed in the substrate 117.

Fig. 3a to 3b are schematic diagrams illustrating a method for forming a quartz crystal resonator according to a second embodiment of the invention.

First, a semiconductor structure as shown in fig. 1j is fabricated. Then, the semiconductor structure shown in fig. 1j is not flipped over, but directly bonded onto the substrate 117 as shown in fig. 1k, resulting in the semiconductor structure shown in fig. 3 a; and then packaged to yield the resonator as shown in figure 3 b.

As can be seen from the figure, in the quartz crystal resonator according to the second embodiment of the present invention, the top projection of the bonding region between the upper substrate layer 101 and the substrate 117 and the top projection of the contact region between the support layer 104 and the quartz piezoelectric layer 109 overlap each other.

Fig. 4a to 4d are schematic diagrams of an electrode lead-out manufacturing process of a quartz crystal resonator according to a second embodiment of the present invention, in which an electrode lead-out structure is led out through a substrate.

The semiconductor structure shown in fig. 4a is similar to the semiconductor structure shown in fig. 3 a;

as shown in fig. 4b, on the basis of the semiconductor structure shown in fig. 4a, a first electrode lead-out layer 113 and a first via hole 118 are fabricated;

as shown in fig. 4c, a package structure 123 is formed over the substrate 117;

as shown in fig. 4d, a second via hole and a second electrode lead-out layer 125 are formed in the substrate 117.

Fig. 5a to 5j are schematic diagrams illustrating a method for forming a quartz crystal resonator according to a third embodiment of the invention.

As shown in fig. 5a, a quartz piezoelectric layer 109 is provided;

as shown in fig. 5b, a first electrode 107 is formed on a quartz piezoelectric layer 109;

as shown in fig. 5c, an adhesion layer 115 is formed on the quartz piezoelectric layer 109;

as shown in fig. 5d, the current semiconductor structure is flipped and then bonded to the cap-shaped reinforcing structure 102;

as shown in fig. 5e, the quartz piezoelectric layer 109 is thinned;

as shown in fig. 5f, a second electrode 111 is formed on the quartz piezoelectric layer 109;

as shown in fig. 5g, an adhesion layer is formed on the quartz piezoelectric layer 109;

as shown in fig. 5h, a substrate 117 with an adhesion layer is provided;

as shown in fig. 5i, the semiconductor structure shown in fig. 5g is turned over and bonded onto a substrate 117, wherein the quartz piezoelectric layer 109 and the substrate 117 are in contact with each other;

as shown in fig. 5j, a package structure 123 is formed over the substrate 117.

As can be seen from the figure, in the quartz crystal resonator according to the third embodiment of the present invention, the top projection of the bonding region between the quartz piezoelectric layer 109 and the substrate 117 and the top projection of the bonding region between the cap-shaped reinforcing structure 102 and the quartz piezoelectric layer 109 overlap each other.

Fig. 6a to 6c are schematic diagrams of the electrode lead-out manufacturing process of the quartz crystal resonator according to the third embodiment of the present invention.

The semiconductor structure shown in fig. 6a is similar to the semiconductor structure shown in fig. 5 i;

as shown in fig. 6b, on the basis of the semiconductor structure shown in fig. 6a, a first electrode lead-out layer 113 is added, and a package structure 123 is added;

as shown in fig. 6c, a second via hole and a second electrode lead-out layer 125 are formed in the substrate 117.

A semiconductor structure as shown in fig. 5g is first fabricated.

As shown in fig. 7a, the semiconductor structure shown in fig. 5g is bonded directly onto the substrate 117 without flipping, wherein the cap-shaped reinforcing structure 102 and the substrate 117 are in contact with each other;

as shown in fig. 7b, a package structure 123 is formed over the substrate 117.

As can be seen from the figure, in the quartz crystal resonator according to the fourth embodiment of the present invention, the top projection of the bonding region between the cap-shaped reinforcing structure 102 and the substrate 117 and the top projection of the bonding region between the cap-shaped reinforcing structure 102 and the quartz piezoelectric layer 109 overlap each other.

The electronic device of the embodiment of the present invention includes any one of the quartz crystal resonators of the present invention.

According to the technical scheme of the embodiment of the invention, the quartz wafer is integrally thinned through MEMS processes such as lapping, chemical mechanical polishing, dry etching and the like, so that the quartz resonance region reaches the target thickness (namely the target frequency), meanwhile, a structure with stronger mechanical stability is configured in a non-resonance region (particularly a connection bonding position with a substrate), the device is insensitive to external stress, mechanical impact and environmental vibration, has higher reliability and frequency stability, can realize large-batch and low-cost manufacture, and the manufactured device has high precision and good consistency.

The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A quartz crystal resonator is characterized by comprising a substrate and a main functional structure which are vertically stacked, wherein the main functional structure comprises a quartz piezoelectric layer, a first electrode, a second electrode and a mechanical reinforcing structure, the substrate and the main functional structure are connected through bonding, the mechanical reinforcing structure is positioned on the quartz piezoelectric layer and bonded with the quartz piezoelectric layer, or the mechanical reinforcing structure is positioned below the quartz piezoelectric layer and bonded with the mechanical reinforcing structure,

the top projection of the contact area of the mechanical enhancement structure and the quartz piezoelectric layer are in contact with each other, and the top projection of the bonding area of the substrate and the main body functional structure are bonded with each other, wherein the two overlap.

2. The quartz crystal resonator of claim 1, wherein the mechanical enhancement structure comprises a support layer and an upper substrate layer.

3. The quartz crystal resonator of claim 1, wherein the mechanical reinforcing structure is a cap-like reinforcing structure.

4. The quartz crystal resonator according to claim 1, wherein the substrate is provided with a cavity in proximity to the functional structure of the body.

5. The quartz crystal resonator of claim 1, further comprising an encapsulation structure.

6. The quartz crystal resonator according to any one of claims 1 to 5, further comprising an electrode lead-out structure led out through the substrate or package structure.

7. A method of forming a quartz crystal resonator, comprising:

providing a quartz piezoelectric layer;

forming a first electrode over the quartz piezoelectric layer;

forming a sacrificial layer over the first electrode;

depositing a support layer on the sacrificial layer and grinding the support layer;

flipping the current semiconductor structure and then bonding to the upper substrate layer;

thinning the quartz piezoelectric layer;

forming a second electrode over the quartz piezoelectric layer;

removing the sacrificial layer;

bonding the current semiconductor structure onto a substrate after being turned over, wherein the quartz piezoelectric layer is mutually contacted with the substrate;

forming an encapsulation structure over the substrate,

wherein, the top projection of the bonding area of the quartz piezoelectric layer and the substrate and the top projection of the contact area of the support layer and the quartz piezoelectric layer are overlapped.

8. A method of forming a quartz crystal resonator, comprising:

providing a quartz piezoelectric layer;

forming a first electrode over the quartz piezoelectric layer;

forming a sacrificial layer over the first electrode;

depositing a support layer over the sacrificial layer and grinding the support layer flat;

thinning the quartz piezoelectric layer;

forming a second electrode over the quartz piezoelectric layer;

removing the sacrificial layer;

bonding the current semiconductor structure directly onto a substrate, wherein the upper substrate layer and the substrate are in contact with each other;

forming an encapsulation structure over the substrate,

wherein, the top projection of the bonding region of the upper substrate layer and the substrate and the top projection of the contact region of the support layer and the quartz piezoelectric layer are overlapped.

9. A method of forming a quartz crystal resonator, comprising:

providing a quartz piezoelectric layer;

forming a first electrode over the quartz piezoelectric layer;

flipping the current semiconductor structure and then bonding to the cap-shaped reinforcing structure;

thinning the quartz piezoelectric layer;

forming a second electrode over the quartz piezoelectric layer;

forming an encapsulation structure over the substrate,

wherein, the top projection of the bonding area of the quartz piezoelectric layer and the substrate and the top projection of the cover-shaped reinforcing structure and the bonding area of the quartz piezoelectric layer have an overlap.

10. A method of forming a quartz crystal resonator, comprising:

providing a quartz piezoelectric layer;

forming a first electrode over the quartz piezoelectric layer;

thinning the quartz piezoelectric layer;

forming a second electrode over the quartz piezoelectric layer;

bonding the current semiconductor structure directly onto a substrate, wherein the cap-shaped reinforcing structure and the substrate are in contact with each other;

an encapsulation structure is formed over the substrate,

wherein, the top projection of the bonding region of the cover-shaped reinforcing structure and the substrate and the top projection of the bonding region of the cover-shaped reinforcing structure and the quartz piezoelectric layer are overlapped.

11. An electronic device characterized by comprising the quartz crystal resonator according to any one of claims 1 to 6.