Semiconductor Bonding Structure Using Al Particles to Relax Thermal Stress
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Solution Overview
Problem
Current semiconductor bonding technologies face challenges with thermal stress relaxation and manufacturing efficiency due to differences in thermal expansion coefficients between semiconductor elements and substrates, leading to crack formation and reduced bonding strength, especially when using metal nanoparticles like Ni, which are hard and prone to oxidation.
Innovation Solution
A semiconductor element bonding structure is developed using micro-sized metal particles with lower hardness and melting point, such as aluminum, interposed between the semiconductor element and the object to be bonded, and fixedly bonded by nano-sized metal particles with a face-centered cubic crystal structure, like Ni, to absorb thermal stress and prevent crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal nanoparticles such as Ni are used for bonding, then bonding strength and heat resistance are improved, but thermal stress relaxation capability deteriorates due to high hardness and embrittlement
Solution Approach 1:
The bonding structure uses a composite material system consisting of micro-sized metal particles (first metal) embedded in a metal nanoparticle matrix (second metal). The micro-sized particles provide thermal stress relaxation through plastic deformation, while the nanoparticle matrix provides bonding strength and heat resistance. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The invention introduces micro-sized metal particles with specific properties (lower hardness, higher ductility) at localized positions within the bonding structure where thermal stress relaxation is needed. These particles are distributed throughout the bonding layer to provide localized stress relaxation zones while maintaining overall bonding strength.
2Stability of the object's composition
If micro-sized metal particles with lower hardness are used, then thermal stress relaxation is improved, but bonding strength deteriorates
Solution Approach 1:
The bonding structure uses a composite material system consisting of micro-sized metal particles (first metal) embedded in a metal nanoparticle matrix (second metal). The micro-sized particles provide thermal stress relaxation through plastic deformation, while the nanoparticle matrix provides bonding strength and heat resistance. This composite structure resolves the contradiction by combining materials with complementary properties.
3Temperature
If sintering bonding of metal nanoparticles is performed, then bonding temperature can be reduced, but embrittlement occurs due to oxygen and carbon uptake
Solution Approach 1:
The micro-sized metal particles act as intermediaries that are less susceptible to embrittlement during sintering. They provide a protective effect on the nanoparticle matrix, reducing the overall embrittlement of the bonding structure. The micro-sized particles serve as a buffer that mitigates the harmful effects of oxygen and carbon uptake during the sintering process.
4Strength
If bonding is performed at high temperature to achieve strong bonding, then bonding strength is improved, but thermal stress increases
Solution Approach 1:
The invention changes the physical parameters of the bonding structure by incorporating micro-sized metal particles with different mechanical properties than the nanoparticle matrix. This parameter change enables the bonding structure to achieve both high bonding strength and thermal stress relaxation capability, as the micro-sized particles can undergo plastic deformation to relieve thermal stress while maintaining structural integrity.
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
This approach enables strong and high-quality bonding while effectively relaxing thermal stress, preventing cracks and gas voids, and maintaining high heat resistance, thus enhancing the bonding strength and manufacturing efficiency.
Implementation Method 1
a plurality of metal particles of a first metal are fixedly bonded by a second metal... sintering bonding of metal nanoparticles have been studied... specific surface area is increased by obtaining metal as nanoparticles to make the surface active, so that bonding can be performed at a relatively low temperature
Implementation Method 2
the first metal has a hardness lower than that of the second metal... the plurality of metal particles of the first metal are interposed between a semiconductor element and an object to be bonded... effectively relaxing thermal stress
Data Source
AI summary
A semiconductor element bonding structure capable of strongly bonding a semiconductor element and an object to be bonded and relaxing thermal stress caused by a difference in thermal expansion, by interposing metal particles and Ni between the semiconductor element and the object to be bonded, the metal particles having a lower hardness than Ni and having a micro-sized particle diameter. A plurality of metal particles 5 (aluminum (Al), for example) having a lower hardness than nickel (Ni) and having a micro-sized particle diameter are interposed between a semiconductor chip 3 and a substrate 2 to be bonded to the semiconductor chip 3, and the metal particles 5 are fixedly bonded by the nickel (Ni). Optionally, aluminum (Al) or an aluminum alloy (Al alloy) is used as the metal particles 5, and aluminum (Al) or an aluminum alloy (Al alloy) is used on the surface of the semiconductor chip 3 and/or the surface of the substrate 2.