Curved Seed Layer Pattern for Semiconductor Package Bump Undercut Control
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Solution Overview
Problem
The downsizing of semiconductor package bumps to increase memory capacity and reduce weight in portable devices leads to increased malfunctions due to excessive undercuts, which weaken bonding strength and cause delamination.
Innovation Solution
A semiconductor package design featuring a seed layer with a curved pattern under the bump, minimizing undercut formation by reducing the etching path length, thereby enhancing bonding strength and reducing manufacturing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bumps are downsized to increase memory capacity and reduce weight, then memory capacity increases and weight decreases, but undercut formation increases causing bonding strength degradation and delamination
Solution Approach 1:
The seed layer is designed with a curved bottom surface instead of a flat surface. This curvature allows the etching solution to access and remove the seed layer more effectively from all angles, minimizing undercut formation beneath the bump structure. The curved geometry ensures uniform etching depth and prevents the formation of weak points that would lead to delamination, thus maintaining bonding strength even as bumps are downsized.
2Quantity of substance
If bumps are downsized to increase memory capacity, then memory capacity increases, but undercut formation increases causing manufacturing defects
Solution Approach 1:
The curved bottom surface of the seed layer enables precise control over the etching process. The curvature geometry ensures that the etching solution can uniformly remove the seed layer material, creating a well-defined interface between the bump and the underlying structure. This precise etching control minimizes undercut formation and eliminates manufacturing defects, even when working with smaller bump dimensions.
3Weight of moving object
If bumps are downsized to reduce weight, then weight decreases, but undercut formation increases causing bonding strength degradation
Solution Approach 1:
The curved bottom surface of the seed layer ensures that even in downsized bumps, the etching process creates a clean, well-defined interface without excessive undercut formation. This maintains the structural integrity and bonding strength of the bump connection, allowing weight reduction through downsizing without compromising mechanical reliability.
Data Source
AI summary
A semiconductor package includes a semiconductor substrate and an electrode pad formed on the semiconductor substrate. The electrode pad includes a central portion and a peripheral portion, and a first pattern is located on the peripheral portion. A passivation layer is formed on the semiconductor substrate and the electrode pad. The passivation layer has an opening exposing the central portion of the electrode pad and a second pattern located on the first pattern. A seed layer is formed on the electrode pad and the passivation layer. The seed layer has a third pattern formed on the second pattern. A bump is formed on the seed layer and electrically connected to the electrode pad. An undercut is formed around the third pattern located under an edge of a lower portion of the bump.