# US 2021/0242848 A1 · Monolithic Integrated BAW Resonator Production Method

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- Number: US 2021/0242848 A1
- Document ID: US20210242848A1
- Status: Published application
- Kind: A1
- Application number: 17/237,611
- Filed: 2021-04-22
- Published: 2021-08-05
- Earliest claimed: 2018-10-23
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Zhengyu He; Huilong Xu
- Web page: https://patentgrep.com/patent/US20210242848A1

## CPC

- H03H 3/02: for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence)
- H03H 9/205: having multiple resonators (crystal tuning forks H03H9/21)
- H03H 2003/0428: {of an electrode}
- H03H 2003/0435: {of a piezoelectric layer}
- H03H 2003/0471: {of a plurality of resonators at different frequencies}
- H03H 2003/0478: {in a process for mass production}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

This application provides a monolithic integrated BAW resonator production method, including: preparing an imprint template; forming a mask material layer on a substrate; pressing the mask material layer by using the imprint template in a direction of the substrate, to form a mask groove; performing plasma etching on the substrate by using the mask material layer, as a mask, that is used to form the mask groove, to form, on the substrate, grooves that one-to-one correspond to positions of several mask grooves; and forming, in the several grooves, bottom electrode layers, piezoelectric layers, and top electrode layers that are sequentially stacked, to form resonators of different frequencies.

## Claims

### Claim at position 1

-10. (canceled)

### Claim 11

A monolithic integrated bulk acoustic wave (BAW) resonator production method, comprising:
forming an imprint template, wherein the imprint template comprises an imprint plate and a plurality of imprint dies protruding from a surface of the imprint plate, and at least two imprint dies of the plurality of imprint dies have different heights relative to the surface of the imprint plate;
forming a mask material layer on a substrate;
pressing the mask material layer in a direction of the substrate using the imprint template, to form, on the mask material layer through imprinting, a mask pattern layer, wherein the mask pattern layer comprises a plurality of mask grooves having depths corresponding to heights of the imprint dies;
plasma etching the substrate using the mask material layer as a mask, to form, on a surface of the substrate, grooves that one-to-one correspond to positions of the plurality of mask grooves, wherein depths of at least two grooves in the grooves are different; and
forming, in the grooves, bottom electrode layers, piezoelectric layers, and top electrode layers that are sequentially stacked, wherein in a direction perpendicular to the substrate, thicknesses of the bottom electrode layers are the same and are all less than depths of the grooves, and piezoelectric layer thicknesses of at least two piezoelectric layers are different, or top electrode layer thicknesses of at least two top electrode layers are different.

### Claim 12 (depends on 11)

The method according to claim 11, wherein forming, in the grooves, the bottom electrode layers, the piezoelectric layers, and the top electrode layers that are sequentially stacked comprises:
forming a bottom electrode layer in each groove of the grooves using the mask pattern layer as a mask and using a first same photolithography process; and
forming the piezoelectric layers on the bottom electrode layers using the mask pattern layer as a mask and using a second same photolithography process, and wherein after the piezoelectric layers are formed, in each groove of the grooves, a sum of a thickness of the bottom electrode layer and a thickness of the piezoelectric layer in the groove is equal to or less than a depth of the groove.

### Claim 13 (depends on 12)

The method according to claim 12, wherein forming the piezoelectric layers on the bottom electrode layers using the mask pattern layer as a mask and using the second same photolithography process, comprises:
forming piezoelectric material layers on the bottom electrode layers using the mask pattern layer as a mask, wherein each piezoelectric material layer protrudes from the surface of the substrate in which the grooves are disposed;
removing the mask pattern layer; and
polishing the piezoelectric material layer until a surface of the piezoelectric material layer is flush with the surface of the substrate, to form the piezoelectric layers.

### Claim 14 (depends on 13)

The method according to claim 13, wherein forming, in the grooves, the bottom electrode layers, the piezoelectric layers, and the top electrode layers that are sequentially stacked comprises:
depositing, on the surface of the substrate, a top electrode material layer that covers the piezoelectric layers; and
patterning the top electrode material layer, to form a top electrode layer on each piezoelectric layer, wherein thicknesses of the top layer electrode layers are the same.

### Claim 15 (depends on 12)

The method according to claim 12, wherein forming, in the grooves, the bottom electrode layers, the piezoelectric layers, and the top electrode layers that are sequentially stacked comprises:
forming the piezoelectric layers on the bottom electrode layers in the grooves by using the mask pattern layer as a mask, wherein after the piezoelectric layers are formed, in each groove of the grooves, a sum of a thickness of the bottom electrode layer and a thickness of the piezoelectric layer is less than a depth of the groove, and wherein thicknesses of the piezoelectric layers in the grooves are the same.

### Claim 16 (depends on 15)

The method according to claim 15, wherein after forming the piezoelectric layers on the bottom electrode layers in the grooves using the mask pattern layer as a mask, the method further comprises:
depositing, using the mask pattern layer as a mask, a top electrode material layer that covers the piezoelectric layers in the grooves;
removing the mask pattern layer after patterning the top electrode material layer, to form, in each groove of the grooves, a top electrode material layer that protrudes from the surface of the substrate out of the groove; and
polishing a protruding part of the top electrode material layers until surfaces of the top electrode material layers are flush with the surface of the substrate, to form the top electrode layers.

### Claim 17 (depends on 11)

The method according to claim 11, wherein when plasma etching is performed on the substrate using the mask pattern layer as a mask, etching is performed by using an Ar+ ion or a He+ ion.

### Claim 18

The method according to claim ii, wherein the mask material layer comprises a high-molecular polymer material, and the substrate comprises an insulating material.

### Claim 19

The method according to claim ii, wherein the imprint template comprises a quartz material and is formed using an ion grinding milling process.

### Claim 20 (depends on 11)

The method according to claim 11, wherein pressing the mask material layer in the direction of the substrate using the imprint template, to form, on the mask material layer through imprinting, the mask pattern layer comprises:
applying specific external force to the imprint template, to press the mask material layer in the direction of the substrate; and
after the substrate on which the imprint template is pressed is heated, removing the imprint template to form the mask pattern layer comprising the plurality of mask grooves.

### Claim 21

A method, comprising:
forming an imprint template, wherein the imprint template comprises an imprint plate and a plurality of imprint dies protruding from a surface of the imprint plate, and at least two imprint dies of the plurality of imprint dies have different heights relative to the surface of the imprint plate;
forming a mask material layer on a substrate;
applying the imprint template to the mask material layer, to form, on the mask material layer, a mask pattern layer, wherein the mask pattern layer comprises a plurality of mask grooves having different depths;
etching the substrate using the mask material layer as a mask, to form, on a surface of the substrate, grooves that correspond to positions of the plurality of mask grooves, wherein depths of at least two grooves in the grooves are different; and
forming, in the grooves, bottom electrode layers, piezoelectric layers, and top electrode layers that are stacked, wherein in a direction perpendicular to the substrate, thicknesses of the bottom electrode layers are the same and are all less than depths of the grooves, and piezoelectric layer thicknesses of at least two piezoelectric layers are different, or top electrode layer thicknesses of at least two top electrode layers are different.

### Claim 22 (depends on 21)

The method according to claim 21, wherein piezoelectric layer thicknesses of the at least two piezoelectric layers are different.

### Claim 23 (depends on 21)

The method according to claim 21, wherein top electrode layer thicknesses of the at least two top electrode layers are different.

### Claim 24 (depends on 21)

The method according to claim 21, wherein etching the substrate using the mask material layer as a mask comprises plasma etching the substrate using the mask material layer as a mask.

### Claim 25 (depends on 24)

The method according to claim 24, wherein the plasma etching is performed by using an Ar+ ion.

### Claim 26 (depends on 24)

The method according to claim 24, wherein the plasma etching is performed by using a He+ ion.

### Claim 27 (depends on 21)

The method according to claim 21, wherein forming, in the grooves, the bottom electrode layers, the piezoelectric layers, and the top electrode layers that are stacked comprises:
forming a bottom electrode layer in each groove of the grooves using the mask pattern layer as a mask and using a first same photolithography process; and
forming the piezoelectric layers on the bottom electrode layers using the mask pattern layer as a mask and using a second same photolithography process.

### Claim 28 (depends on 27)

The method according to claim 27, wherein forming, in the grooves, the bottom electrode layers, the piezoelectric layers, and the top electrode layers that are stacked further comprises:
depositing a top electrode material layer that covers the piezoelectric layers; and
patterning the top electrode material layer, to form a top electrode layer on each piezoelectric layer, wherein thicknesses of the top layer electrode layers are the same.