Protruding Electrode Tapered Geometry for Semiconductor Reliability
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Solution Overview
Problem
The existing semiconductor devices and wiring substrates with protruding electrodes face reliability issues due to constricted roots, which are prone to cracks or breaks under thermal stress, especially when the pitch or diameter is narrowed, leading to decreased connection reliability.
Innovation Solution
The semiconductor device and wiring substrate designs feature a protruding electrode with a pedestal part and a protruding part, including a tapered and columnar part, where the columnar part has a smaller width than the pedestal part, and the tapered part's width increases towards the pedestal part, with a larger angle of inclination, preventing excessive etching and root constriction during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pitch or diameter of the protruding electrode is narrowed, then the device size is reduced, but the connection reliability deteriorates due to root constriction
Solution Approach 1:
The protruding electrode is divided into three distinct parts: a pedestal part, a tapered part, and a columnar part. This segmentation allows each part to serve a specific function - the pedestal part provides a broad base for support, the tapered part acts as a transition zone that prevents stress concentration, and the columnar part provides the protruding terminal. By segmenting the electrode structure, the patent eliminates root constriction while maintaining small device size.
Solution Approach 2:
Different sections of the protruding electrode are given different geometric properties tailored to their specific functions. The pedestal part has a larger width for stability, the tapered part has a gradually changing width for stress distribution, and the columnar part has a smaller width for compactness. This local differentiation of geometric qualities allows the electrode to maintain reliability while being miniaturized.
2Ease of manufacture
If the protruding electrode is formed by conventional etching method, then the manufacturing process is simple, but the root constriction occurs reducing connection reliability
Solution Approach 1:
The patent applies preliminary action by forming the tapered part with a specific inclination angle greater than 45 degrees before the final etching process. This preliminary geometric configuration ensures that during subsequent etching, the etchant cannot reach the root area, preventing constriction before it occurs. The preliminary shaping of the tapered part acts as a protective measure that maintains reliability while allowing simple manufacturing processes to continue.
Solution Approach 2:
The tapered part serves as an intermediary structure between the pedestal part and the columnar part. Its specific geometric configuration (inclination angle > 45 degrees) acts as a mediator that blocks the etchant from reaching the root area during the etching process, thereby preventing root constriction while allowing the etching process to proceed simply without requiring complex process modifications.
3Quantity of substance
If the pitch of protruding electrodes is reduced, then the electrode density increases, but thermal stress causes cracks in the root area
Solution Approach 1:
By segmenting the electrode into pedestal, tapered, and columnar parts, the patent creates a structure where the tapered part specifically addresses thermal stress issues. The segmentation allows the tapered part to function as a stress-distributing element that prevents crack formation in high-density configurations.
Solution Approach 2:
The tapered part is given a specific local geometric quality (inclination angle > 45 degrees) that enhances its ability to distribute thermal stress. This local quality modification in the tapered section provides thermal stress resistance precisely where needed, enabling high electrode density without compromising strength.
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 enhances connection reliability by preventing root constriction, ensuring stable performance even when the pitch or diameter of the protruding electrode is reduced, thereby improving thermal stress resistance.
Implementation Method 1
a protruding part is formed on the metal layer exposed to the inside of the opening by, for example, an electrolytic plating method
Data Source
AI summary
A semiconductor device has a semiconductor substrate, an electrode pad formed on a surface of the semiconductor substrate, and a protruding electrode electrically connected to the electrode pad. The protruding electrode comprises a pedestal part formed on the electrode pad and a protruding part formed on the pedestal part. The protruding part has a columnar part with a width smaller than that of the pedestal part, and a tapered part with a width gradually increased from an end of the columnar part side toward an end of the pedestal part side. An angle of inclination of a side surface of the tapered part with respect to a plane surface perpendicular to the surface is larger than an angle of inclination of a side surface of the pedestal part and an angle of inclination of a side surface of the columnar part with respect to the plane surface.