Semiconductor Package Bump Pad Recess Structure
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Solution Overview
Problem
Semiconductor packages face challenges in miniaturization and reliability due to excessive protrusions of bump structures, leading to potential shorts and quality degradation during chip stacking, especially when bump structures on neighboring pads bond together under compression.
Innovation Solution
Incorporating recess structures on bump pads to guide the protrusion direction of bump structures, preventing bonding between neighboring structures and enhancing electrical characteristics and reliability by ensuring proper alignment and contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bump structures are made with fine sizes to achieve miniaturization, then the capacity of semiconductor devices increases, but the risk of excessive protrusion and short circuit between neighboring bumps increases
Solution Approach 1:
The bump pad structure is modified to have different properties in different regions: a first region with larger area for stable bonding, and a second region with smaller area to limit protrusion. This local differentiation allows the bump structure to achieve both fine size for high capacity and controlled protrusion for reliability.
2Productivity
If distances between bump structures are reduced to increase density, then more connections can be made in limited space, but neighboring bumps may bond together under compression
Solution Approach 1:
The bump pad is designed with spatially varying dimensions where the first region provides adequate bonding area for reliable connections, while the second region's reduced area creates physical constraints that prevent excessive protrusion and short circuits between closely spaced bumps.
Solution Approach 2:
The recess structure is formed in advance on the bump pad before the bump structure is attached. This preliminary geometric configuration guides the protrusion direction and limits the extent of protrusion during subsequent compression bonding, preventing short circuits before they can occur.
3Strength
If bump structures protrude excessively during bonding, then adhesion strength may increase, but short circuits between neighboring structures occur
Solution Approach 1:
The bump pad structure differentiates between regions needed for strong adhesion (first region with larger area) and regions that must constrain protrusion (second region with smaller area). This allows the system to achieve both strong bonding and prevention of harmful protrusion-induced short circuits.
Data Source
AI summary
A semiconductor package includes a first substrate having a first surface and including a first electrode, a first bump pad located on the first surface of the first substrate and connected to the first electrode, a second substrate having a second surface facing the first surface of the first substrate and including a second electrode, a second bump pad and neighboring second bump pads on the second surface of the second substrate, and a bump structure. The second bump pad has a recess structure. That is recessed from a side surface of the second bump pad toward a center thereof. The second bump pad may be connected to the second electrode. A bump structure may contact the first bump pad and the second bump pad. The bump structure may have a portion protruding through the recess structure. The neighboring second bump pads may neighbor the second bump pad and include recess structures oriented in different directions.