Segmented Diffusion Barrier Film for Solder Bump Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor devices with miniaturized solder-joints experience thermal stress concentration at the junction between the semiconductor chip and the mounting substrate, leading to potential cracking due to differences in thermal expansion coefficients, and existing stress relaxation methods are inadequate.
Innovation Solution
A semiconductor device with a diffusion barrier film having a geometry with spacings is used, dividing the junction into multiple small areas to disperse thermal stress effectively, reducing concentration and enhancing stress relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diffusion barrier film is made as a continuous hard disc-shaped structure, then the electrode is well protected from solder diffusion, but thermal stress concentrates at the junction between the bump and the UBM, potentially causing cracks
Solution Approach 1:
The continuous diffusion barrier film is divided into multiple separate diffusion barrier portions arranged in an array, with each portion corresponding to a solder bump. The spacing between these portions creates stress relief zones that prevent stress concentration while maintaining diffusion protection at each bump junction.
2Area of stationary object
If the spacing between terminal leads is reduced to increase the number of terminals, then the package size can be minimized, but thermal stress concentration at the solder bump junction increases due to miniaturization
Solution Approach 1:
By segmenting the diffusion barrier film into multiple discrete portions with spacing between them, the structure maintains a compact footprint suitable for miniaturized packages while the spaced arrangement provides inherent stress relief that prevents crack propagation in the miniaturized configuration.
Solution Approach 2:
The diffusion barrier portions are strategically positioned only where needed—at each solder bump junction—rather than forming a continuous coverage. This localized approach reduces overall material presence and stress accumulation points while maintaining protective function at critical interfaces.
3Reliability
If the diffusion barrier film is made continuous and hard, then diffusion protection is maximized, but stress relaxation is inhibited leading to crack formation in the aluminum electrode or semiconductor chip
Solution Approach 1:
The continuous diffusion barrier is segmented into discrete portions with spacing between them. Each portion maintains its hard, diffusion-resistant properties, while the spacing between portions acts as a stress relief zone that allows thermal expansion and contraction, preventing stress concentration and crack formation.
Solution Approach 2:
The spaced regions between diffusion barrier portions act as intermediary stress relief zones. These regions mediate between the hard diffusion barrier portions and the underlying aluminum electrode, absorbing and distributing thermal stress to prevent transmission of concentrated forces that would cause cracking.
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 solution significantly reduces thermal stress concentration at the junction, improving the reliability of the semiconductor device by preventing cracking and maintaining electrode integrity during temperature cycling tests.
Implementation Method 1
a diffusion barrier film for preventing a diffusion of a material composing the bump is provided on a surface of the electrode
Implementation Method 2
the diffusion barrier film is formed to have a geometry including an spacing... strain may be possibly concentrated on the solder-bump junction... the stress tends to be concentrated in particular on the circumference portion
Data Source
AI summary
The present invention provides a semiconductor device exhibiting an improved reliability. A semiconductor device comprises a semiconductor chip having an electrode on a surface thereof and a mounting substrate, and the electrode (aluminum electrode) of the semiconductor chip is coupled to the mounting substrate through a bump (solder bump 104). A plurality of diffusion barrier films (UBM 112) for preventing a diffusion of a material composing the bump is provided between the electrode and the bump, and the diffusion barrier film is formed to have a plurality of divided portions via spacings therebetween.