Metal Nitride Core-Shell Die Attach for Oxidation-Resistant Bonding
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Solution Overview
Problem
Existing die-attach materials for semiconductor devices face challenges such as high cost, risk of electromigration, voiding/porosity, thermo-mechanical stresses, and non-compliance with lead-free certification standards, particularly in wide band gap semiconductor applications.
Innovation Solution
A core-shell particle-based die-attach material is developed, comprising a conducting core, such as copper, surrounded by a metal nitride shell, which reduces oxidation and allows for bonding without forming gas, offering enhanced stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional die-attach materials are used, then cost is reduced and manufacturing is simplified, but reliability deteriorates due to electromigration risk, voiding/porosity, and thermo-mechanical stresses
Solution Approach 1:
The patent employs a composite core-shell particle structure where the core provides electrical conductivity and the shell provides oxidation resistance. This composite structure resolves the contradiction by combining materials with complementary properties to achieve high reliability without requiring complex external protective systems.
Solution Approach 2:
The invention applies local quality by providing oxidation protection only where needed - on the surface shell of the particles - while maintaining the conductive core's electrical properties. This localized approach improves reliability against oxidation and electromigration without adding overall structural complexity.
2Manufacturing precision
If conventional die-attach materials are used, then manufacturing process is simplified, but manufacturing precision deteriorates due to voiding and porosity
Solution Approach 1:
The oxidation resistance is built into the particle structure beforehand through the shell formation process. This preliminary protective action prevents oxidation-related defects during storage and application, improving manufacturing precision without requiring complex controlled atmosphere processes during the actual bonding operation.
3Reliability
If lead-free materials are used, then compliance with certification standards is improved, but performance deteriorates due to inadequate thermomechanical properties
Solution Approach 1:
The invention changes the material parameters by using copper cores with controlled particle size distributions and shell thicknesses to achieve both lead-free compliance and superior thermomechanical properties. The core-shell structure allows optimization of thermal conductivity, mechanical strength, and compliance with lead-free standards simultaneously.
4Stability of the object's composition
If copper particles are used without protection, then electrical conductivity is improved, but stability deteriorates due to oxidation
Solution Approach 1:
The shell acts as an intermediary layer between the copper core and the oxidizing environment. This intermediate protective structure allows the copper core to maintain its electrical conductivity while the shell provides the necessary oxidation resistance, resolving the contradiction between conductivity and stability.
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 die-attach material provides improved aging stability, lower defects and voids, and meets lead-free certification standards while maintaining high thermomechanical and electrical properties.
Implementation Method 1
a metal nitride shell, which reduces oxidation
Implementation Method 2
bonding the die-attach material
Data Source
AI summary
Die attach materials are provided. In one example, the die-attach material includes a plurality of core-shell particles. Each core-shell particle includes a core and a shell on the core. The core includes a conducting material. The shell includes a metal nitride.