High-frequency surface acoustic wave resonator and preparation method thereof

A high-frequency surface acoustic wave and resonator technology, applied in the direction of impedance network, electrical components, etc., can solve the problems of high preferred orientation, thermal stress material deformation and cracking of multi-layer film structure, and achieve high electromechanical coupling coefficient, low working temperature, The effect of reducing thermal stress

Pending Publication Date: 2022-05-17

SOUTH CHINA UNIV OF TECH

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AI-Extracted Technical Summary

Problems solved by technology

However, most of the piezoelectric films obtained by the deposition process are polycrystalline, and it is difficult to obtain a high preferred orientation, which leads to the generation of parasitic clutter and makes it difficult to control the frequency response of the device.

The single crystal piezoelectric thin film is generally prepared by direct bonding process, but this process generally requires annealing at a temperature greater than 400°C. Due to the different thermal expan...

Method used

The introduction of the bottom electrode 103 is in order to realize the low-temperature bonding transfer of the high-sonic substrate 102 and the piezoelectric film 104, so that the thermal stress after the transfer is greatly reduced, and at the same...

Abstract

The invention discloses a high-frequency surface acoustic wave resonator and a preparation method thereof, relates to a microelectronic device for 5G communication, and provides the scheme for solving the problems of high bonding transfer temperature, low electromechanical coupling coefficient and the like in the prior art. A first bonding metal layer is arranged on the end face, away from the first substrate, of the high-sound-velocity substrate, a second bonding metal layer is arranged on the end face, away from the interdigital electrode, of the piezoelectric film, and bonding processing of the piezoelectric film and the high-sound-velocity substrate is completed through the first bonding metal layer and the second bonding metal layer. The method has the advantages that the method is compatible with a low-temperature metal bonding process, the working temperature of metal bonding is lower, and the thermal stress of a device can be greatly reduced. And secondly, metal bonding can enable a bonding interface to obtain higher bonding energy, and the device is more stable. Besides, the X-cut lithium niobate is used as the piezoelectric film, and the included angle of 44 degrees is formed between the vertical direction of the interdigital electrode and the Z axis of the piezoelectric film, so that a higher electromechanical coupling coefficient can be obtained, and the bandwidth of the device is improved.

Application Domain

Impedence networks

Technology Topic

Metallic bondingThin membrane +9

Image

Examples

Comparison scheme(1)

Comparison Example

[0051] The device structures of Comparative Example 1 and Comparative Example 2 are as follows: figure 2 As shown, it includes an interdigital electrode 105, a piezoelectric thin film 104, a high-sonic velocity substrate 102 and a first substrate 101 that are stacked in sequence. The difference between the first comparative example and the present embodiment is that the bottom electrode 103 between the high-sonic velocity substrate 102 and the piezoelectric film 104 is reduced. The difference between Comparative Example 2 and Comparative Example 1 is that the X-cut lithium niobate piezoelectric film is replaced with a commonly used 128°Y-cut lithium niobate piezoelectric film, and the vertical direction of the interdigital electrode 105 is the same as that of the piezoelectric film 104 . The X axis is parallel.

[0052] like Figure 11 As shown, compared with Comparative Example 1, the addition of the bottom electrode 103 can still excite the high speed of sound in the piezoelectric film 104, and the frequency and electromechanical coupling coefficient of this mode have no particular impact, only the extreme value is slightly reduced. There is narrowing. It is proved that the introduction of the bottom electrode 103 has no obvious negative effect on the device performance.

[0053] like Figure 12 As shown, the resonant frequency and anti-resonance frequency of Comparative Example 1 are 7.557 and 8.045 GHz, respectively, and the resonant frequency and anti-resonant frequency of Comparative Example 2 are 7.906 and 7.919 GHz, respectively. Compared with Comparative Example 2, the electromechanical coupling coefficient of Comparative Example 1 increased from 0.41% to 15.00%. Therefore, compared with the commonly used cut shapes, the cut shapes described in this embodiment can obtain higher electromechanical coupling coefficients at similar frequencies.

[0054] To sum up, in the embodiments of the present application, a larger electromechanical coupling coefficient can be obtained under the condition of high frequency by means of the new piezoelectric thin film cutting. And by arranging the bottom electrode 103 under the piezoelectric film 104, the hypersonic mode is still effectively excited, and its frequency and electromechanical coupling coefficient are not affected. In addition, the structure is compatible with low-temperature metal bonding technology, which can greatly reduce the thermal stress generated during the transfer process and avoid cracks during the annealing process. At the same time, a larger bonding energy can be obtained, which is beneficial to improve the stability of the device.

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Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

lower working temperature
reduce thermal stress

High-frequency surface acoustic wave resonator and preparation method thereof

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Image

Examples

Comparison Example

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Description & Claims & Application Information

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