Silicon Oxycarbide Acoustic Wave Layer for High-Power Temperature Compensation

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Solution Overview

Problem

Existing acoustic wave devices face challenges with temperature compensation, particularly at high power levels, where silicon dioxide layers can crack due to low fracture toughness, and require materials with improved mechanical properties for reliable operation.

Innovation Solution

Incorporating an amorphous silicon oxycarbide layer with a stoichiometric formula of SiO2(1-Z)CZ, where 0<Z<1, as a temperature compensation layer, which provides higher fracture toughness, hardness, and thermal conductivity, reducing parasitic surface conduction and enhancing electrical insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a silicon dioxide layer is used for temperature compensation, then temperature compensation is achieved, but the layer cracks due to low fracture toughness at high power levels

Engineering Contradiction:

Improvetemperature compensation reliabilityVSAvoidfracture toughness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the material composition parameters by incorporating carbon into the silicon oxide matrix, creating silicon oxycarbide with variable stoichiometry (SiOxNyCz). This compositional parameter change increases fracture toughness while maintaining temperature compensation properties, resolving the contradiction between reliability and strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by combining silicon, oxygen, nitrogen, and carbon elements in specific ratios. The silicon oxycarbide layer (SiOxNyCz) acts as a composite material that integrates the beneficial properties of each element: silicon oxide for temperature compensation, carbon for enhanced fracture toughness and hardness, and nitrogen for additional mechanical property optimization.

Inventive Principle:

Principle #40Composite materials

2Strength

If the temperature compensation layer material is hardened to prevent cracking, then fracture toughness improves, but acoustic loss properties worsen

Engineering Contradiction:

Improvefracture toughnessVSAvoidacoustic loss

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The patent optimizes the stoichiometric parameters (x, y, z in SiOxNyCz) to achieve a balanced composition. By controlling the ratios of oxygen, nitrogen, and carbon content, the material achieves sufficient fracture toughness while maintaining acoustic transparency, thus resolving the contradiction between strength and acoustic loss.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies the principle of local quality by ensuring the temperature compensation layer has locally optimized composition throughout its structure. The uniform distribution of silicon, oxygen, nitrogen, and carbon elements creates consistent local properties that simultaneously provide mechanical strength and minimal acoustic loss across the entire layer.

Inventive Principle:

Principle #3Local quality

3Strength

If the temperature compensation layer provides high hardness, then mechanical strength improves, but parasitic surface conduction increases

Engineering Contradiction:

ImprovehardnessVSAvoidparasitic surface conduction

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent adjusts the compositional parameters of the silicon oxycarbide layer, specifically controlling the carbon content (z parameter in SiOxNyCz) to optimize the balance between hardness and electrical properties. By limiting excessive carbon accumulation, the material maintains high hardness while preventing the formation of conductive carbon-rich phases that would cause parasitic surface conduction.

Inventive Principle:

Principle #35Parameter changes

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 amorphous silicon oxycarbide layer effectively compensates for temperature-related frequency shifts, reduces mechanical failures, and improves acoustic loss properties, ensuring stable operation at high power levels by increasing the modulus of rupture and elastic modulus while maintaining suitable thermal expansion coefficients.

Implementation Method 1

maintaining suitable thermal expansion coefficients

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

compensates for temperature-related frequency shifts

Methodology Applied

Scientific EffectElastic modulus temperature dependence:

Implementation Method 3

provides higher fracture toughness, hardness, and thermal conductivity

Methodology Applied

Scientific EffectThermal conductivity: Conduction (thermal)

Data Source

PatentUS20230336147A1Acoustic wave device including silicon oxycarbide layer

Publication Date: 2023.10.19 SKYWORKS SOLUTIONS INC

AI summary

Aspects of this disclosure relate to an acoustic wave device with a silicon oxycarbide layer over a trap rich layer. The acoustic wave device can include a piezoelectric layer over the silicon oxycarbide. The acoustic wave device can be a surface acoustic wave device in certain applications. The acoustic wave device can be a bulk acoustic wave device in some other applications. Related acoustic wave filters, radio frequency modules, wireless communication devices, and methods are disclosed.