Rare Earth Metal Bonding Material for Hermetic Microchip Sealing
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Solution Overview
Problem
Conventional methods for bonding microchips, such as using glass seals or thermocompression bonding, face challenges like increased die size, contamination, and restricted topography requirements, which limit the efficiency and cost-effectiveness of microchip fabrication.
Innovation Solution
A bonding material containing a rare earth metal is used to facilitate chip-to-chip or wafer-to-wafer bonding, forming a hermetic seal and electrical connection with minimal surface restrictions, allowing for versatile application and process flexibility, including the use of solder or thermocompression materials and deposition processes to create narrow bond structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass seal is used to bond silicon die caps to MEMS chip, then hermetic seal is achieved, but seal footprint increases die size
Solution Approach 1:
The patent changes the material parameter from glass to metal bonding material containing rare earth metals, which enables hermetic sealing with significantly reduced footprint. The rare earth metal content (0.1-15.0 volume percent) modifies the bonding material's properties to achieve both hermeticity and small area occupation.
Solution Approach 2:
The bonding material is a composite consisting of metal matrix with rare earth metal additives. This composite structure combines the hermetic sealing capability of metals with the enhanced bonding properties provided by rare earth metals, achieving both reliability and compact size.
2Reliability
If glass seal is used to bond substrates, then hermetic seal is achieved, but electrically isolating the cap from die requires additional wirebonding that increases package height
Solution Approach 1:
The metal bonding material with rare earth metals performs multiple functions simultaneously: it provides hermetic sealing, electrical connection, and mechanical bonding. This eliminates the need for separate wirebonding operations, reducing package height while maintaining reliability.
Solution Approach 2:
The patent merges the sealing function and electrical connection function into a single bonding material system. The metal matrix provides electrical conductivity while the rare earth metals ensure hermetic sealing, combining previously separate functions into one integrated solution.
3Object-generated harmful factors
If thermocompression bonding with metal is used to bond substrates, then glass seal issues are avoided, but high pressures require wafers to have minimal topography
Solution Approach 1:
The patent modifies the pressure parameter by incorporating rare earth metals into the bonding material, which enable effective bonding at lower pressures. This reduces the stringency of topography requirements while maintaining the benefits of metal bonding over glass sealing.
Solution Approach 2:
The rare earth metals act as intermediaries that facilitate bonding between the metal matrix and substrate surfaces. They enable effective bonding at reduced pressures by mediating the interaction between bonding surfaces, thereby relaxing topography constraints.
4Ease of manufacture
If conventional bonding materials are used, then bonding is achieved, but bonding material does not readily bond with substrate in absence of rare earth metal
Solution Approach 1:
The patent changes the chemical composition parameter by adding rare earth metals (0.1-15.0 volume percent) to the bonding material. This compositional modification enhances both bond strength and bonding processability, making the material more reactive and adhesive to substrate surfaces.
Solution Approach 2:
The bonding material is formulated as a composite with rare earth metal particles dispersed in a metal matrix. This composite structure provides both the mechanical properties of the metal matrix and the enhanced bonding characteristics of rare earth metals, achieving superior bond strength and ease of manufacture.
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 rare earth metal-based bonding material reduces chip size, increases fabrication yield, and lowers per-unit costs by enabling efficient bonding with minimal surface preparation and alignment requirements, while providing a conductive and hermetic seal.
Implementation Method 1
The rare earth metal facilitates bonding because, in various embodiments, the other material does not readily bond with the first substrate in the absence of the rare earth metal
Implementation Method 2
The bonding material may form a hermetic seal, electrically connect the first substrate and the second substrate, or both
Implementation Method 3
The bonding material may form a hermetic seal, electrically connect the first substrate and the second substrate, or both
Data Source
AI summary
A microchip has a bonding material that bonds a first substrate to a second substrate. The bonding material has, among other things, a rare earth metal and other material.