Cu-Al Electrode Interface Structure to Suppress Al Slide
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Solution Overview
Problem
In semiconductor devices with a laminated structure of aluminum and copper electrode layers, stress due to differences in linear expansion coefficients leads to 'Al slide,' where the aluminum electrode layer detaches or deforms, causing reliability issues at high temperatures.
Innovation Solution
A semiconductor device design featuring an aluminum electrode layer, a first copper electrode layer with protruding regions towards the aluminum layer, and a second copper electrode layer with larger crystal grains, which enhances the hardness and adhesion at the interface, thereby suppressing stress-induced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a laminated structure of aluminum electrode layer and copper electrode layer is used for high-temperature operation, then the operating temperature capability is improved, but stress concentration and Al slide occur due to linear expansion coefficient differences
Solution Approach 1:
The copper electrode layer is designed with non-uniform crystal grain sizes: a first region with smaller crystal grains near the aluminum interface to provide high hardness and stress resistance, and a second region with larger crystal grains at the top surface for stress absorption. This local variation in microstructure optimizes both high-temperature stability and stress distribution.
Solution Approach 2:
The electrode structure uses a composite laminated design of aluminum and copper layers, combining materials with different thermal expansion coefficients and mechanical properties. The copper layer acts as a buffer to accommodate thermal stress while maintaining electrical conductivity and structural integrity at high temperatures.
2Strength
If the copper electrode layer has large crystal grains, then the hardness is reduced making Al slide more likely, but if the copper electrode layer has small crystal grains throughout, then stress absorption capability is reduced
Solution Approach 1:
The copper electrode layer is designed with non-uniform crystal grain sizes: a first region with smaller crystal grains near the aluminum interface to provide high hardness and stress resistance, and a second region with larger crystal grains at the top surface for stress absorption. This local variation in microstructure optimizes both high-temperature stability and stress distribution.
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 design effectively suppresses the 'Al slide' phenomenon at high temperatures, enhancing the reliability of semiconductor devices by reducing stress concentrations and maintaining structural integrity.
Implementation Method 1
the first copper electrode layer includes a plurality of protruding regions as regions protruding toward the aluminum electrode layer in an interface with the aluminum electrode layer
Implementation Method 2
a second copper electrode layer provided on an upper surface of the first copper electrode layer, having crystal grains larger than crystal grains in the first copper electrode layer
Implementation Method 3
stress occurs in accordance with a difference of a linear expansion coefficient between the aluminum electrode layer, the copper electrode layer on the aluminum electrode layer, and a module member
Data Source
AI summary
Provided is a semiconductor device capable of suppressing an Al slide at a time of an operation under a high temperature in a laminated structure of an aluminum electrode layer and a copper electrode layer. Accordingly, in the semiconductor device according to the present disclosure, a first copper electrode layer includes a plurality of protruding regions as regions protruding toward the aluminum electrode layer in an interface with the aluminum electrode layer.