Buffer Layer Reduces Stress in Semiconductor Coupling Parts
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Solution Overview
Problem
Semiconductor devices with multilayered wiring experience stress at coupling parts with different widths, leading to cracks and breaks, particularly in polysilicon wiring and resistive elements due to their poor ductility.
Innovation Solution
A semiconductor device design incorporating a buffer layer made of a softer material than the inorganic insulating layers, positioned between the coupling part and a pad with a bump, to absorb applied forces and reduce stress on the coupling part, which can be conductive and electrically coupled to the wiring, and made of polysilicon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysilicon wiring is used in multilayered semiconductor devices, then electrical functionality is achieved, but stress concentration occurs at coupling parts between different width sections leading to cracks and breaks
Solution Approach 1:
A buffer layer is introduced as an intermediary component between the polysilicon wiring and the pad structure. This buffer layer absorbs stress and prevents direct transmission of mechanical forces to the vulnerable coupling part of the wiring, thereby maintaining wiring reliability without compromising the structural integrity at width transition sections.
Solution Approach 2:
The buffer layer is positioned in advance at locations where stress concentration is expected to occur, specifically between the coupling part and the pad. This preemptive placement cushions against future stress applications from bumps or thermal expansion, preventing cracks and breaks before they can develop in the polysilicon wiring.
2Reliability
If a buffer layer is added to reduce stress at coupling parts, then wiring reliability improves, but device structure becomes more complex
Solution Approach 1:
The buffer layer is applied selectively only at critical stress concentration zones, specifically at coupling parts between different width sections of the wiring and at interfaces with pads. This localized application provides stress relief where needed most without adding buffer layers throughout the entire device, thereby limiting the increase in structural complexity to only essential areas.
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 buffer layer effectively absorbs forces applied to the coupling part, reducing stress and preventing cracks and breaks in the wiring, allowing for reliable operation of the semiconductor device.
Implementation Method 1
The buffer layer is made of a material other than resin and softer than the inorganic insulating layer... even though a force is applied to the coupling part between the parts with different widths by the bump, the force is absorbed by the buffer layer
Data Source
AI summary
A semiconductor device includes a semiconductor chip, wiring that is included in the semiconductor chip and his a coupling part between parts with different widths, a pad being formed above the wiring and in a position overlapping the coupling part, a bump being formed on the pad, a buffer layer being formed in a position between the coupling part and the pad so as to cover the entire couple part, and inorganic insulating layers being formed between the wiring and the buffer layer and between the buffer layer and the pad, respectively. The buffer layer is made of a material other than resin and softer than the inorganic insulating layer.