Single-Crystal Thin Film Bonding Layer for Lower Acoustic Loss

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Solution Overview

Problem

Micron-scale monocrystal films face challenges in reducing acoustic wave loss and insertion loss due to defects and stress between the substrate and the monocrystal film layer, which affect the quality and performance of filters and other optical devices.

Innovation Solution

A micron-scale monocrystal film structure is developed with a transition layer interposed between the substrate and the monocrystal film layer, containing hydrogen and plasma gas elements like Ar, O2, and N2, which enhances bonding and reduces stress, thereby improving the film's quality and reducing wave loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a monocrystal film is directly bonded to a substrate, then bonding strength is improved, but stress concentration and defects occur at the interface

Engineering Contradiction:
Improvebonding strengthVSAvoidinterface defect density
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

A transition layer is introduced between the substrate and monocrystal film layer. This transition layer contains H and plasma gas elements (Ar, O2, N2) that act as intermediaries to improve bonding while reducing stress concentration and preventing interface defects.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The transition layer is formed as a composite structure containing multiple elements (H, Ar, O2, N2) that work together to provide both bonding enhancement and stress relief functions, creating a multi-functional interface region.

Inventive Principle:
Principle #40Composite materials

2Strength

If the transition layer contains high hydrogen concentration, then bonding force is enhanced, but material stability may be compromised

Engineering Contradiction:
Improvebonding forceVSAvoidmaterial stability
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The hydrogen concentration in the transition layer is precisely controlled within the range of 1×10^20 to 1×10^22 atoms/cm3. This parameter optimization ensures sufficient bonding force while preventing excessive hydrogen that would compromise material stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Hydrogen is localized specifically in the transition layer rather than uniformly distributed throughout the structure. This local concentration provides bonding enhancement at the interface while maintaining stability in the bulk monocrystal film and substrate.

Inventive Principle:
Principle #3Local quality

3Reliability

If plasma gas elements are added to the transition layer, then stress distribution is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvestress distributionVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Plasma treatment is performed on the substrate and monocrystal film surfaces before bonding. This preliminary action introduces plasma gas elements (Ar, O2, N2) into the interface region, which then provide stress distribution benefits during subsequent device operation.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The transition layer with a specific hydrogen concentration range (1 × 10^20 to 1 × 10^22 atoms/cm3) effectively disperses stress, reduces defects, and enhances bonding force, leading to lower acoustic wave loss and insertion loss in filters.

Implementation Method 1

The transition layer includes H and an element of at least one kind of plasma gas used during the plasma bonding of the substrate layer and micron monocrystal layer

Methodology Applied
Scientific EffectHydrogen bonding: Chemical Bonding

Implementation Method 2

the transition layer includes H and an element of at least one kind of plasma gas used during the plasma bonding of the substrate layer and micron monocrystal layer

Methodology Applied
Scientific EffectPlasma bonding: Plasma

Implementation Method 3

The transition layer with a specific hydrogen concentration range (1 × 10^20 to 1 × 10^22 atoms/cm3) effectively disperses stress, reduces defects, and enhances bonding force, leading to lower acoustic wave loss

Methodology Applied
Scientific EffectStress relaxation: Stress Relaxation

Data Source

PatentEP3731287B1Micron-scale single-crystal thin film
Publication Date: 2024.05.01 JINAN JINGZHENG ELECTRONICS
  • EP3731287B1 patent drawingFigure 1~2
  • EP3731287B1 patent drawingFigure 3
  • EP3731287B1 patent drawingFigure 4

AI summary

The invention provides a micron-scale monocrystal film. The micron-scale monocrystal film includes 1) a substrate layer, and 2) a micron-scale monocrystal film layer located on the substrate layer, wherein a transition layer is interposed between the substrate layer and micron-scale monocrystal film layer, and the transition layer may include a first transition layer disposed adjacent to the substrate layer and a second transition layer disposed adjacent to the micron monocrystal film layer, wherein the transition layer may include H and an element from at least one kind of plasma gas used during the plasma bonding of the substrate layer and the micron-scale monocrystal film layer.