Composite substrate, elastic wave device, and method for producing elastic wave device

• US 10,629,470 B2
• Filed: 11/03/2017
• Issued: 04/21/2020
• Est. Priority Date: 02/19/2013
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Hattori, Ryosuke, Hori, Yuji, Tai, Tomoyoshi
• Primary Examiner(s): Tugbang, A. Dexter
• Application Number:
  US15/802,967
• Publication Number:
  US 20180053679A1
• Time in Patent Office: 900 Days
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: B32B 2264/105 Metal
• CPC Class Codes: B32B 2307/20 having particular electrical or magnetic properties, e.g. piezoelectric
• CPC Class Codes: B32B 2307/206 Insulating
• CPC Class Codes: B32B 2307/538 Roughness
• CPC Class Codes: B32B 2309/02 Temperature
• CPC Class Codes: B32B 2309/105 Thickness
• CPC Class Codes: B32B 2457/00 Electrical equipment
• CPC Class Codes: B32B 2457/14 Semiconductor wafers
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/20 using fillers, pigments, thixotroping agents
• CPC Class Codes: B32B 27/283 comprising polysiloxanes
• CPC Class Codes: B32B 37/10 characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
• CPC Class Codes: B32B 38/10 Removing layers, or parts of layers, mechanically or chemically
• CPC Class Codes: B32B 7/025 Electric or magnetic properties
• CPC Class Codes: B32B 7/06 permitting easy separation
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: B32B 9/005 comprising one layer of ceramic material, e.g. porcelain, ceramic tile layered products with at least two ceramic layers composed mainly of ceramic B32B18/00
• CPC Class Codes: B32B 9/04 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a glass layer B32B17/06; layered products with at least two ceramic layers composed mainly of ceramic B32B18/00
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 21/78 : with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304
• CPC Class Codes: H03H 2003/022 : the resonators or networks being of the cantilever type
• CPC Class Codes: H03H 2003/023 : the resonators or networks being of the membrane type
• CPC Class Codes: H03H 2003/027 : the resonators or networks being of the microelectro-mechanical [MEMS] type
• CPC Class Codes: H03H 3/02 : for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 3/08 : for the manufacture of resonators or networks using surface acoustic waves
• CPC Class Codes: H03H 3/10 : for obtaining desired frequency or temperature coefficient
• CPC Class Codes: H03H 9/02574 : of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
• CPC Class Codes: H03H 9/1014 : the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the BAW device
• CPC Class Codes: H03H 9/1035 : the enclosure being defined by two sealing substrates sandwiching the piezoelectric layer of the BAW device
• CPC Class Codes: H03H 9/105 : the enclosure being defined by a cover cap mounted on an element forming part of the BAW device
• CPC Class Codes: H03H 9/25 : Constructional features of resonators using surface acoustic waves devices for manipulating acoustic surface waves in general G10K11/36
• CPC Class Codes: H10N 30/072 : by laminating or bonding of piezoelectric or electrostrictive bodies
• CPC Class Codes: H10N 30/8542 : Alkali metal based oxides, e.g. lithium, sodium or potassium niobates
• CPC Class Codes: Y10T 29/42 : Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 : Acoustic transducer
• CPC Class Codes: Y10T 428/12597 : Noncrystalline silica or noncrystalline plural-oxide component [e.g., glass, etc.]

Abstract

A method for producing an elastic wave device includes steps of (a) preparing a first substrate and a second substrate, (b) irradiating a bonding surface of the first substrate and a bonding surface of the second substrate with one of plasma, neutral atom beams, and ion beams of an inert gas, (c) bonding the bonding surface of the first substrate and the bonding surface of the second substrate in a vacuum at room temperature so as to set a strength that allows the first and second substrates to be separated by insertion of a blade; (d) forming a composite substrate by bonding a piezoelectric substrate to another surface of the first substrate; (e) forming electrode on a surface of the piezoelectric substrate of the composite substrate; and then (f) removing the second substrate from the first substrate by separation with the blade.

Claims

1. A method for producing an elastic wave device comprising the steps of:

(a) preparing a first substrate and a second substrate;

(b) irradiating a bonding surface of the first substrate and a bonding surface of the second substrate with one of plasma, neutral atom beams, and ion beams of an inert gas;

(c) bonding the bonding surface of the first substrate and the bonding surface of the second substrate in a vacuum at room temperature so as to set a strength that allows the first substrate and the second substrate to be separated by insertion of a blade having a thickness of 100 μ

m;

(d) forming a composite substrate by bonding a piezoelectric substrate to another surface of the first substrate that is opposite to the bonding surface of the first substrate;

(e) forming electrodes on a surface of the piezoelectric substrate of the composite substrate; and

(f) after forming the electrodes (c) step, removing the second substrate from the first substrate by separation with the blade,

wherein the first substrate and the second substrate are formed of a same material and each of the first substrate and the second substrate has a lower thermal expansion coefficient than that of the piezoelectric substrate.

2. The method for producing an elastic wave device according to claim 1, further comprising the step of:

(g) after removing the second substrate from the first substrate, dicing the composite substrate to obtain the elastic wave device.

3. The method for producing an elastic wave device according to claim 1,

wherein the first and second substrates are both silicon substrates.

4. The method for producing an elastic wave device according to claim 1,

wherein the strength that allows separation with the blade corresponding to a bonding energy per unit area of the first and second substrates is in a range of 0.05 to 0.06 J/m².

5. The method for producing an elastic wave device according to claim 1,

wherein an iron element and a chromium element are contained between the bonding surface of the first substrate and the bonding surface of the second substrate.