AlN Ceramic Joint Composition for Hermetic Flat Assemblies
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Solution Overview
Problem
Existing methods for bonding aluminum nitride components in semiconductor processing equipment, such as electrostatic chucks and heaters, face challenges in maintaining geometrical flatness and properties due to high-temperature and high-pressure processes, which can compromise the microstructure and dimensions of precisely engineered devices, and often result in poor thermal shock resistance and hermeticity.
Innovation Solution
A composite glass-ceramic joint using Y2O3—Al2O3—SiO2 (YAS) glass with crystalline aluminosilicate and aluminum nitride filler particles, which enables low-temperature and low-pressure joining, providing a dense, strong, and hermetic bond while matching the coefficient of thermal expansion of aluminum nitride, thus enhancing thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature and high-pressure co-firing is used to bond aluminum nitride ceramics, then hermetic joint is achieved, but geometrical flatness and microstructure properties deteriorate
Solution Approach 1:
The patent changes the temperature and pressure parameters of the bonding process by using a low melting point glass (Tg=1100-1300°C) as a bonding aid, enabling bonding at lower temperatures (1000-1300°C) and pressures compared to traditional co-firing methods. This parameter change resolves the contradiction by achieving hermetic joints without the extreme conditions that cause geometrical distortion and microstructure degradation.
Solution Approach 2:
The patent introduces a glass-based bonding aid as an intermediary material between the aluminum nitride ceramic components. This glass layer facilitates bonding at lower temperatures and pressures while maintaining hermeticity, thereby avoiding the geometrical flatness and microstructure problems caused by direct high-temperature co-firing of ceramics.
2Strength
If re-firing of pre-sintered ceramic is performed at high temperatures and pressures, then bonding is achieved, but microstructure, dimensions, and properties are compromised
Solution Approach 1:
The patent changes the bonding temperature and pressure parameters by utilizing a low melting point glass (melting point 1100-1300°C) as a bonding aid. This enables achieving strong bonding at lower temperatures (1000-1300°C) and pressures, thereby preserving the pre-sintered ceramic's microstructure, dimensions, and properties while still obtaining adequate bonding strength.
3Reliability
If extensive processing steps and long firing profiles are used, then joint properties are maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for extensive processing steps and long firing profiles by using a low melting point glass-based bonding aid. The simplified process involves applying the glass paste, assembling components, and firing at lower temperatures for shorter durations, thereby reducing manufacturing complexity and cost while maintaining joint properties through the glass's inherent bonding capabilities.
4Strength
If dissimilar materials with mismatched thermal expansion coefficients are used, then bonding is achieved, but thermal shock resistance deteriorates
Solution Approach 1:
The patent applies homogeneity by selecting a glass-based bonding aid whose thermal expansion coefficient matches that of aluminum nitride ceramics. This thermal expansion matching creates a homogeneous thermal response across the joint, eliminating stress concentrations and improving thermal shock resistance while maintaining bonding strength.
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 solution forms a robust, hermetic joint with high theoretical density and low porosity, maintaining the properties of the aluminum nitride components and ensuring reliable performance in corrosive environments, such as those containing halogen gases.
Implementation Method 1
a Y2O3—Al2O3—SiO2 (YAS) glass phase which enables flow across the joint and liquid-phase diffusion bonding with the AlN ceramic bodies
Implementation Method 2
AlN filler particles to restrict overflow of the glass and reduce the differences in the coefficient of thermal expansion across the joint, thereby enhances the joint's thermal shock resistance
Data Source
AI summary
This invention relates to an assemblage of a semiconductor processing apparatus comprising a first aluminum nitride (AlN) component and a second aluminum nitride component, wherein the first and second aluminum nitride components are connected by a joint, said joint comprising a composite glass-ceramic comprising Y2O3—Al2O3—SiO2 (YAS) glass; and at least one of crystalline aluminosilicate and aluminum nitride.