Offset Pillar Electrode for Semiconductor Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices with pillar-shaped electrodes experience peeling off at the joining interface due to repetitive stress from temperature cycle tests, caused by differences in linear expansion coefficients between the wiring substrate and the semiconductor chip, leading to reliability issues.
Innovation Solution
A semiconductor device design where the pad is partially covered with a protective insulating film, and the pillar-shaped electrode is formed with a first portion on the opening region of the pad and a second portion extended over the protective insulating film, with the center position of the pillar-shaped electrode shifted from the opening region, enhancing the contact area and reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pillar-shaped electrode is centered on the opening region of the pad, then the alignment and manufacturing process is simpler, but the joining interface experiences higher stress concentration and peeling off occurs under heat load
Solution Approach 1:
The pillar-shaped electrode is intentionally positioned asymmetrically relative to the opening region, with its center offset from the center of the opening. This asymmetric positioning shifts the stress distribution pattern, preventing stress concentration at the bonding pad-pillar electrode interface during thermal cycling, thereby preventing peeling off while maintaining manufacturing feasibility
Solution Approach 2:
The protective insulating film is selectively formed to cover specific regions including the bonding pad and surrounding areas, creating different protective qualities in different locations. This local differentiation provides enhanced protection to the joining interface region while allowing the pillar electrode to maintain electrical connection, thus improving reliability without compromising manufacturing simplicity
2Reliability
If the protective insulating film covers the entire pad, then the protection against stress and environmental factors is enhanced, but the electrical connection between the pillar electrode and pad is compromised
Solution Approach 1:
The protective insulating film is formed with spatially varying coverage: it completely covers the bonding pad region to provide stress protection and environmental isolation, while leaving the opening region exposed to allow electrical connection. This local differentiation in protective coverage resolves the contradiction between protection and electrical connectivity
Solution Approach 2:
The pad structure is segmented into functionally distinct regions: the bonding pad region covered by the protective insulating film for mechanical protection, and the opening region left exposed for electrical connection. This segmentation allows each region to fulfill its specific function without interfering with the other, achieving both protection and connection accuracy
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 design improves the reliability of the semiconductor device by reducing peeling off at the joining interface and enhancing the connection strength between the pad and the pillar-shaped electrode, even under heat load conditions.
Implementation Method 1
a difference in a linear expansion coefficient between the wiring substrate and the semiconductor chip
Data Source
AI summary
The reliability of a semiconductor device is improved. A probe mark is formed on a probe region of a pad covered with a protective insulating film. And, a pillar-shaped electrode has a first portion formed on an opening region and a second portion that is extended over the probe region from the upper portion of the opening region. At this time, a center position of the opening region is shifted from a center position of the pillar-shaped electrode that is opposed to a bonding finger.