Polycrystalline Nanodiamond Elastic Wave Device
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Solution Overview
Problem
Elastic wave devices using diamond-based materials fail to achieve good resonance characteristics due to propagation loss issues.
Innovation Solution
The elastic wave device incorporates a polycrystalline nanodiamond layer with 50% or more sp3 bonds, a crystalline diamond underlayer, and a piezoelectric body, where the polycrystalline nanodiamond layer is thin enough to prevent warping and reduce material consumption, and includes tungsten or tantalum to relax stress and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a hard carbon film composite of graphitic diamond and carbon clusters is used, then propagation loss is reduced, but resonance characteristics are poor
Solution Approach 1:
The patent changes the bonding structure parameter of the diamond-based material by specifying sp3 bond percentages (50-100%) to transform the material properties from graphitic diamond with poor resonance characteristics to polycrystalline nanodiamond with improved resonance characteristics while maintaining low propagation loss
Solution Approach 2:
The patent uses a composite structure consisting of a polycrystalline nanodiamond layer (with sp3 bonds ≥50%) combined with a piezoelectric body and IDT electrode, creating a composite material system that achieves both low propagation loss and good resonance characteristics
2Loss of substance
If the polycrystalline nanodiamond layer is made thin to reduce material consumption, then the device becomes thinner and material usage decreases, but the layer may warp during formation
Solution Approach 1:
The patent optimizes the thickness parameter of the polycrystalline nanodiamond layer to be within a specific range (0.1λ to 0.5λ, where λ is the wavelength determined by IDT finger pitch), which balances material reduction with structural stability during formation
Solution Approach 2:
The patent incorporates stress-relaxing elements (W or Ta) in advance within the polycrystalline nanodiamond layer to prevent warping during formation, addressing the stability issue before it occurs
3Strength
If the polycrystalline nanodiamond layer includes W or Ta to relax stress, then cracking is prevented, but device complexity increases
Solution Approach 1:
The patent adds stress-relaxing elements (W or Ta) locally within the polycrystalline nanodiamond layer structure, incorporating them as specific compositional components that target the stress concentration areas without redesigning the entire device structure
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 device exhibits improved resonance characteristics and filter characteristics with minimal spurious emissions and high impedance ratios, achieving efficient elastic wave propagation and confinement.
Implementation Method 1
a piezoelectric body provided directly or indirectly on the at least one inorganic material layer
Implementation Method 2
The piezoelectric body propagates an elastic wave at a higher velocity than the polycrystalline nanodiamond layer propagates a bulk wave
Data Source
AI summary
An elastic wave device includes a support substrate, a polycrystalline nanodiamond layer provided directly or indirectly on the support substrate, at least one inorganic material layer provided on the polycrystalline nanodiamond layer, a piezoelectric body provided directly or indirectly on the at least one inorganic material layer, and an IDT electrode provided directly or indirectly on the piezoelectric body. The piezoelectric body propagates an elastic wave at a higher velocity than the polycrystalline nanodiamond layer propagates a bulk wave, and at a lower velocity than the at least one inorganic material layer propagates a bulk wave. The polycrystalline nanodiamond layer has a percentage of sp3 bonds of about 50% or more.