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Film bulk acoustic resonator with passivation layer and preparation method thereof

A thin-film bulk acoustic wave and passivation layer technology, applied in electrical components, impedance networks, etc., can solve problems such as poor protection effect, and achieve the effects of improving temperature stability, improving mechanical strength, and improving sensitivity

Pending Publication Date: 2021-07-23
浙江星曜半导体有限公司
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  • Summary
  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

[0004] The inventor believes that the passivation layer used in the prior art only plays the role of isolating the resonator from the external environment, and the protection effect is poor, and there is room for improvement

Method used

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  • Film bulk acoustic resonator with passivation layer and preparation method thereof
  • Film bulk acoustic resonator with passivation layer and preparation method thereof
  • Film bulk acoustic resonator with passivation layer and preparation method thereof

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preparation example Construction

[0047] Such as Figure 2-Figure 13 As shown, a method for preparing a thin film bulk acoustic resonator with a passivation layer according to the present invention comprises the following steps:

[0048] S1, cleaning the substrate 1 formed by a high-resistance silicon wafer with a suitable thickness for standby, the thickness of the substrate 1 can be between hundreds of microns to thousands of microns;

[0049] S2. After the substrate 1 with a specific thickness is obtained, it is oxidized, and then a layer of silicon dioxide is grown on the surface of the substrate 1 as a sacrificial layer 9. The thickness of the sacrificial layer 9 can be between several hundred nanometers and several microns. between;

[0050] S3. Process the sacrificial layer 9 through photolithography, that is, process the sacrificial layer 9 by coating photoresist, mask exposure, dry etching, and removing photoresist, and finally process the sacrificial layer 9 into an isosceles trapezoidal cross secti...

example 1

[0062] The method for forming the bottom electrode 3 or top electrode 4 in steps S5 and S7 can also be to perform metal evaporation or sputtering first, and then perform photolithography and dry etching to form the bottom electrode 3 or top electrode 4 .

[0063] Variation 2

[0064] The bottom electrode 3 is connected to the electrical signal, and the top electrode 4 is connected to the ground.

[0065] working principle

[0066] When there is a potential difference between the bottom electrode 3 and the top electrode 4 , the electric field between them can effectively excite acoustic resonance in the piezoelectric layer 2 . The introduction of the air cavity 6 forms a metal-air interface between the substrate 1 and the oscillation area of ​​the resonator, which can effectively confine the sound wave in the piezoelectric oscillation stack and maintain the mechanical strength of the resonator. In addition, the double-layer passivation layer composed of the first passivat...

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Abstract

The invention provides a film bulk acoustic resonator with passivation layers and a preparation method thereof. The film bulk acoustic resonator comprises a substrate, a piezoelectric layer, a bottom electrode, a top electrode, a first passivation layer and a second passivation layer, the piezoelectric layer is arranged above the substrate, an air cavity is arranged between the piezoelectric layer and the substrate, the bottom electrode is arranged between the piezoelectric layer and the substrate, and the top electrode is arranged above the piezoelectric layer; the first passivation layer completely covers the top electrode and the piezoelectric layer, and the second passivation layer is located above the first passivation layer and completely covers the first passivation layer. The air cavity is adopted, and an interface of metal and air is formed between the substrate and the oscillation area of the resonator, so that sound waves can be limited in an oscillation pile, and the mechanical strength of the resonator is improved; through the cooperation of the first passivation layer and the second passivation layer, the resonator can be effectively isolated from the external environment, the temperature drift coefficient of the resonator is reduced, and the resonant frequency of the resonator can be sensitively adjusted by cutting the thickness of the second passivation layer.

Description

technical field [0001] The invention relates to the technical field of resonator manufacture, in particular to a thin-film bulk acoustic wave resonator with a passivation layer and a preparation method. Background technique [0002] With the rapid development of 5G communication technology, thin film bulk acoustic resonator has become one of the most promising basic devices. In the processing and manufacturing process of the acoustic wave resonator, in order to reduce the influence of the surrounding environment on the resonator and improve the stability of the resonator, it is often necessary to introduce a passivation layer into the resonator. [0003] The existing Chinese patent with publication number CN102025340B discloses an acoustic wave resonator and its processing method. The acoustic wave resonator includes: a base with an air cavity, a bottom passivation layer, an oscillation stack and a top passivation layer. Two passivation layers above and below the oscillatin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H3/02H03H9/02
CPCH03H3/02H03H9/02
Inventor 高安明姜伟
Owner 浙江星曜半导体有限公司
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