Composite Piezoelectric Substrate Bonding for 300°C High Resistance
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Solution Overview
Problem
Existing methods for manufacturing composite substrates using silicon as a support substrate for piezoelectric materials like lithium tantalate and lithium niobate face challenges with dielectric loss and mechanical strength due to silicon's thermal expansion coefficient mismatch and oxygen content, leading to slip and cracking issues.
Innovation Solution
A method involving bonding a silicon wafer with an interstitial oxygen concentration of 2 to 10 ppma to a piezoelectric material substrate, optionally with an intervening layer, and thinning the piezoelectric material after bonding, using surface activation treatments to enhance bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal back electrode is used in OLED displays, then electrical conductivity is improved, but ion migration and display degradation occur
Solution Approach 1:
The patent replaces the traditional metal back electrode with a transparent conductive oxide (TCO) layer, creating a composite structure that combines the electrical conductivity needed for operation with the ion-blocking properties of oxide materials. This composite approach eliminates ion migration while maintaining electrical functionality and improving display reliability.
Solution Approach 2:
The invention changes the material parameter from metal to transparent conductive oxide, fundamentally altering the chemical and physical properties of the electrode. This parameter change eliminates the harmful ion migration effect while preserving electrical conductivity and adding transparency for OLED display applications.
2Object-generated harmful factors
If transparent conductive oxide layers are used to replace metal electrodes, then ion migration is prevented, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the traditional metal-based electrode system with a transparent conductive oxide system that can be deposited using vapor phase techniques. This substitution simplifies the manufacturing process by enabling direct formation of the electrode layer without complex assembly steps, while simultaneously preventing ion migration.
3Productivity
If conventional sputtering methods are used for TCO deposition, then deposition speed is maintained, but step coverage and film quality deteriorate
Solution Approach 1:
The patent employs a dynamic deposition process using vapor phase techniques where the substrate can be rotated or moved during deposition. This dynamic approach ensures uniform step coverage and film quality while maintaining high deposition speeds, overcoming the limitations of static conventional sputtering methods.
Solution Approach 2:
The invention replaces conventional sputtering with vapor phase deposition methods that inherently provide better step coverage. The vapor phase process allows material to conformally deposit on complex substrate geometries, achieving high manufacturing precision without sacrificing deposition productivity.
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 method maintains high resistance up to 300°C, preventing slip and cracking while minimizing dielectric loss, thus ensuring stable device performance.
Implementation Method 1
a transparent conductive oxide layer in a display device can block ion migration
Implementation Method 2
Vapor phase deposition of transparent conductive oxide for large area substrates
Data Source
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AI summary
A composite substrate capable of maintaining high resistance after processing at 300°C and a method of manufacturing the composite substrate are provided. The composite substrate according to the present invention is manufactured by bonding a silicon (Si) wafer having an interstitial oxygen concentration of 2 to 10 ppma to a piezoelectric material substrate as a support substrate, and thinning the piezoelectric material substrate after the bonding. The piezoelectric material substrate is particularly preferably a lithium tantalate wafer (LT) substrate or a lithium niobate (LN) substrate.