Pd/Pt Aluminum Wiring Composition for High-Temperature Bond Reliability
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Solution Overview
Problem
Aluminum (Al) wiring materials used in semiconductor devices face challenges in achieving high bond reliability and durability, particularly in high-temperature environments, due to issues like peeling defects and reduced bonding strength, which are exacerbated by the formation of voids at the bonded interface and temperature fluctuations.
Innovation Solution
An Al wiring material with specific compositions and microstructural characteristics, including the addition of Pd and Pt, controlled crystal grain diameter, and orientation ratios, which enhances the bonding effective area ratio (EBR) and tensile strength, thereby improving the reliability and durability of the bonded interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high purity Al is used as wiring material, then electrical conductivity is improved, but bond reliability deteriorates in high-temperature environments due to softening
Solution Approach 1:
The patent applies parameter changes by precisely controlling the content of Fe and Si impurities within specific ranges (Fe: 0.003-0.06 mass%, Si: 0.003-0.06 mass%) and controlling the average crystal grain diameter to 3-35 μm. These parameter optimizations prevent excessive softening at high temperatures while maintaining bond reliability, resolving the contradiction between purity and temperature resistance.
Solution Approach 2:
The patent creates a composite microstructure by controlling the presence of Fe and Si elements together with Al, forming a multi-phase material system. This composite approach at the microstructural level enhances high-temperature stability and bond reliability while maintaining the base Al conductivity, addressing the contradiction between purity and temperature resistance.
2Strength
If crystal grain diameter is reduced to improve strength, then tensile strength is improved, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent applies parameter changes by establishing a specific target range for average crystal grain diameter (3-35 μm) and providing controlled manufacturing methods. This parameter optimization achieves sufficient tensile strength (≥25 MPa) while maintaining manufacturability, resolving the contradiction between strength and manufacturing precision.
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 proposed Al wiring material significantly enhances the bond reliability and durability in high-temperature environments by reducing voids and improving the bonding effective area ratio, leading to improved performance and longevity of semiconductor devices.
Implementation Method 1
The Al wiring material contains Fe and Si in specific amounts to suppress generation of unbonded region (void) at the time of bonding
Implementation Method 2
an average crystal grain diameter on a cross-section perpendicular to a longitudinal direction of the Al wiring material is 3 to 35 μm
Implementation Method 3
when the semiconductor devices operate by switching high voltage on and off at high speed, it is exposed to a severe environment where the temperature is repetitively increased and decreased
Data Source
AI summary
There is provided an Al wiring material which can achieve sufficient bond reliability of bonded parts in a high-temperature environment at the time when a semiconductor device operates. The Al wiring material containing one or more of Pd and Pt so as to satisfy3≤x1a≤90 or 10≤x1b≤250, and3≤(x1a+x1b)≤300,where x1a and x1b are respectively a content of Pd [mass ppm] and a content of Pt [mass ppm],with the balance comprising Al, andan average crystal grain diameter on a cross-section perpendicular to a longitudinal direction of the Al wiring material is 3 to 35 μm.