Manufacturing method of a composite substrate of an acoustic wave resonator

Patent metadata

Field	Value
Publication number	US-12224730-B2
Application number	US-202017618690-A
Country	US
Kind code	B2
Filing date	Jul 1, 2020
Priority date	Jan 8, 2020
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

The present invention discloses a composite substrate for manufacturing an acoustic wave resonator and a Surface Acoustic Wave (SAW) resonator, and a manufacturing method thereof. The manufacturing method of the composite substrate includes: providing a base, wherein the base includes a first surface and a second surface that are opposite to each other; and a first groove sunken towards the second surface is formed on the first surface; and providing a piezoelectric plate, wherein the piezoelectric plate is matched with the first groove in shape, and a bottom of the first groove is integrated with the piezoelectric plate by bonding; and the composite substrate includes: a base, wherein the base includes a first surface and a second surface that are opposite to each other; and a first groove sunken towards the second surface is provided on the first surface; and a piezoelectric plate, wherein the piezoelectric plate is embedded into the first groove, and a top of the piezoelectric plate is higher than the first surface or flush with the first surface.

First claim

What is claimed is:

1. A manufacturing method of a composite substrate of an acoustic wave resonator, comprising:
providing a base, wherein the base comprises a first surface and a second surface that are opposite to each other; and
a first groove sunken towards the second surface is formed on the first surface; and
providing a piezoelectric plate and embedding the piezoelectric plate into the first groove, wherein the piezoelectric plate is matched with the first groove in shape, and a bottom of the first groove is integrated with the piezoelectric plate by bonding;
forming a protrusion on the bottom of the first groove, and forming a second groove on a bottom of the piezoelectric plate; or, forming the second groove on the bottom of the first groove, and forming the protrusion on the bottom of the piezoelectric plate,
wherein the protrusion and the second groove are matched in shape, and positioned in a non-device region of the composite substrate; and
wherein when the piezoelectric plate is embedded into the first groove, the second groove and the protrusion are clamped together.

2. The manufacturing method according to claim 1 , wherein the bonding comprises one of covalent bonding, adhesive bonding and fusion bonding;
wherein the adhesive bonding comprises: forming an adhesive on the bottom of the first groove and/or the piezoelectric plate, and bonding the base and the piezoelectric plate with the adhesive; and
the fusion bonding comprises: forming a first bonding layer in the first groove and/or forming a second bonding layer on the bottom of the piezoelectric plate, and bonding the base and the piezoelectric plate through the bonding layer;
wherein a material for the first bonding layer and/or the second bonding layer comprises: silicon oxide, nitrogen oxide, polysilicon or metal.

3. The manufacturing method according to claim 1 , before the bonding, further comprising: forming an acoustic wave reflection layer on the bottom of the first groove and/or a bottom of the piezoelectric plate;
the acoustic wave reflection layer is a single film layer or a plurality of film layers;
a material for the acoustic wave reflection layer at least comprises one of silicon carbide, silicon nitride, boron nitride, molybdenum, aluminum, tungsten, thallium and potassium.

4. The manufacturing method according to claim 1 , before the bonding, further comprising: forming a stress buffering layer on the bottom of the first groove.

5. The manufacturing method according to claim 4 , further comprising: forming a stress compensation layer on the stress buffering layer;
the base is a silicon base, the stress buffering layer is made of silicon oxide, and the stress compensation layer is made of silicon nitride.

6. The manufacturing method according to claim 5 , wherein the stress buffering layer and the stress compensation layer respectively have a thickness of 0.08-1 μm; and/or
the first bonding layer or the second bonding layer has a thickness of 0.3-1 μm.

7. The manufacturing method according to claim 1 , before the bonding, first forming an acoustic wave reflection layer on the bottom of the first groove, and then forming a stress buffering layer and a stress compensation layer;
or, first forming the stress buffering layer and the stress compensation layer on the bottom of the first groove, and then forming the acoustic wave reflection layer;
or, forming the stress buffering layer and the stress compensation layer in the first groove, at least either the stress buffering layer or the stress compensation layer serving as the acoustic wave reflection layer.

8. The manufacturing method according to claim 1 , wherein the method for forming the protrusion comprises: patterning the bottom of the first groove or the bottom of the piezoelectric plate to form the protrusion;
or, forming a dielectric layer or a polysilicon layer on the bottom of the first groove or the bottom of the piezoelectric plate, and etching the dielectric layer or the polysilicon layer to form the protrusion.

9. The manufacturing method according to claim 1 , wherein
the protrusion is formed on the bottom of the first groove, and before or after the protrusion is formed, the stress buffering layer and the stress compensation layer, and/or the acoustic wave reflection layer are formed in the first groove;
a top of the piezoelectric plate is higher than the base, and after the piezoelectric plate and the base are bonded, the manufacturing method further comprises: performing a grinding and thinning process on the piezoelectric plate; and
the protrusion is formed on the bottom of the first groove, the protrusion serves as a grinding stop layer of the grinding and thinning process, or, the grinding stop layer is formed on a top of the protrusion;
the protrusion is formed on the bottom of the first groove, the protrusion is made of a dielectric layer or polysilicon, and the protrusion is distributed on a cutting channel and is of a strip structure.

10. The manufacturing method according to claim 9 , wherein the top of the protrusion is higher than or flush with the first surface, and the top of the protrusion is not covered by the piezoelectric plate.

11. The manufacturing method according to claim 1 , wherein after the piezoelectric plate is integrated with the first groove, a top of the piezoelectric plate is flush with the first surface or higher than the first surface.

12. The manufacturing method according to claim 1 , wherein a top of the piezoelectric plate is higher than the first surface, and the manufacturing method further comprises: thinning an upper surface of the piezoelectric plate to form a plane with an upper surface of the composite substrate, the thinning process comprising the following steps:
thinning the piezoelectric plate to 25-35 μm by mechanically grinding the top of the piezoelectric plate;
thinning the piezoelectric plate to 4-6 μm with chemo-mechanical rough grinding;
thinning the piezoelectric plate to 0.6-0.7 μm with Chemo-Mechanical Polishing (CMP); and
trimming the upper surface of the piezoelectric plate through an ion beam trimming process, the trimmed piezoelectric plate having a surface thickness uniformity of less than 2%;
wherein after performing the ion beam trimming on the top of the piezoelectric plate, further comprising:
annealing the piezoelectric plate with a furnace tube or a laser to repair lattice damage of the piezoelectric plate.

Assignees

• Ningbo Semiconductor Int Corp

Inventors

• Huang Herb He
• Luo Hailong
• Li Wei
• Qi Fei

Classifications

• H03H9/25

  Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} · CPC title

• H03H3/08 Primary

  for the manufacture of resonators or networks using surface acoustic waves · CPC title

• H03H9/02559

  of lithium niobate or lithium-tantalate substrates · CPC title

• H03H3/02

  for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence) · CPC title

• H03H9/02574 Primary

  of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate · CPC title