Stepped Through Electrode for Semiconductor Package Coupling
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Solution Overview
Problem
Semiconductor packages, particularly chip-stack packages, face challenges in miniaturization and densification, leading to reduced coupling strength between through electrodes and connecting terminals, which affects the reliability of electrical connections.
Innovation Solution
A semiconductor device design featuring through electrodes and connecting terminals with a larger size ratio, where the connecting terminals are formed integrally with the through electrodes and have a rough surface, increasing the contact area and adhesiveness, and a metal layer is applied to enhance solder wettability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If through electrodes are miniaturized to achieve further densification of semiconductor packages, then the size of the package is reduced, but the coupling strength between through electrodes and connecting terminals decreases
Solution Approach 1:
The invention transitions from a single-diameter through electrode design to a multi-layered structure with different diameters at different heights. The through electrode has a first diameter in the lower portion and a second diameter in the upper portion, creating a stepped configuration. This dimensional change allows the electrode to maintain adequate coupling strength at both the substrate level and the chip level while minimizing the overall package footprint.
Solution Approach 2:
The through electrode is designed with non-uniform local properties - specifically, different diameters at different locations along its length. The lower portion has a larger diameter for strong coupling with the substrate, while the upper portion has a different diameter for optimal coupling with the connecting terminal. This local quality variation resolves the contradiction by optimizing each interface separately.
2Productivity
If through electrodes are made smaller to increase integration density, then more chips can be stacked, but the reliability of electrical connections deteriorates
Solution Approach 1:
The stepped structure of the through electrode, with different diameters at different heights, enables high integration density while maintaining connection reliability. The varied diameter profile allows multiple chips to be stacked closely (high density) while each connection interface maintains adequate contact area (high reliability).
Solution Approach 2:
The through electrode employs a composite structure combining materials with different properties at different sections. The lower portion uses a material optimized for substrate bonding, while the upper portion uses a material optimized for chip terminal bonding. This composite approach maintains reliability across both interfaces despite miniaturization.
3Strength
If connecting terminals are formed with larger size to improve coupling strength, then the contact area increases, but the package area occupied by wire loops increases
Solution Approach 1:
The invention resolves the area conflict by utilizing the vertical dimension. Instead of increasing the horizontal footprint of connecting terminals, the through electrode achieves larger effective contact area through increased height with varied diameters. The stepped structure provides extended surface area for coupling without expanding the planar package footprint, thus maintaining high coupling strength within a compact area.
Solution Approach 2:
The through electrode structure acts as a flexible coupling element that can be optimized in height and diameter profile independently of the package footprint. This allows the coupling strength to be enhanced through vertical dimension optimization rather than horizontal expansion, effectively decoupling the strength-area trade-off.
Data Source
AI summary
A semiconductor device includes a semiconductor substrate. The semiconductor substrate includes a first surface, a second surface, and a through hole that extends through the semiconductor substrate from the first surface to the second surface. An insulating layer covers the first surface and includes an opening at a location facing the through hole. An insulating film covers an inner wall of the through hole and an inner wall of the opening. A through electrode is formed in the through hole and the opening that are covered by the insulating film. A first connecting terminal is formed integrally with the through electrode to cover one end of the through electrode exposed from the insulating layer. The first connecting terminal has a larger size than the through electrode as viewed from above.