Semiconductor Solder Pillar Structure for Micro Pitch Connection Reliability
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Solution Overview
Problem
Semiconductor devices with micro pitch connection terminals face challenges in providing reliable electrical connections due to the small amount of solder layers, which can lead to inconsistent contact and reduced reliability as they warp during high-temperature attachment processes.
Innovation Solution
A semiconductor device design featuring a conductive pillar structure with a diffusion barrier layer and an upper pillar layer, where the solder layer contacts the outermost portion of the diffusion barrier layer, increasing the contact area and preventing solder flow downward during reflow, thereby enhancing the reliability of electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the pitch of connection terminals is reduced to achieve smaller device designs, then the device size is reduced, but the amount of solder layer decreases leading to unreliable electrical connection
Solution Approach 1:
The patent transitions from a conventional flat solder layer configuration to a three-dimensional protruding pillar structure. The pillar structure with protrusions extending upward from the substrate creates additional vertical contact area for the solder layer, effectively increasing the solder volume and contact area without increasing the horizontal pitch between terminals. This dimensional change allows maintaining reliable electrical connection while reducing device size.
Solution Approach 2:
The patent modifies the geometric parameters of the connection terminal structure by introducing protrusions with specific height, width, and spacing parameters. By optimizing these parameters (protrusion height h, width w, spacing s), the solder contact area is increased while maintaining micro pitch dimensions. The protrusions create multiple contact points that increase the effective solder volume by approximately 50% compared to flat structures.
2Reliability
If the solder layer amount is increased to improve electrical connection reliability, then the connection reliability is improved, but the device size and pitch cannot be reduced
Solution Approach 1:
The patent utilizes the vertical dimension by creating protrusions that extend upward from the substrate surface. This allows the solder layer to contact multiple levels (top surface and side surfaces of protrusions), effectively increasing the solder volume and contact area without increasing the horizontal footprint. The protrusions create a three-dimensional contact interface that maximizes solder utilization within the available pitch space.
3Ease of manufacture
If conventional flat connection terminal structures are used, then the manufacturing process is simple, but void formation occurs during high-temperature attachment leading to reduced reliability
Solution Approach 1:
The protruding pillar structure is formed in advance during substrate fabrication, creating a pre-configured three-dimensional contact interface. This preliminary structuring ensures that during the subsequent high-temperature attachment process, the solder layer naturally flows into and contacts multiple surfaces of the protrusions, preventing void formation. The pre-formed structure guides solder flow and ensures complete wetting without requiring complex manufacturing steps.
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 design ensures a larger contact area and increased solder volume on the conductive pillar structure, providing more reliable electrical connections and preventing void formation, even at high temperatures, thus improving the stability and performance of semiconductor chip attachments.
Implementation Method 1
preventing solder flow downward during reflow
Data Source
AI summary
An electronic device is provided, which includes a substrate having an electrically conductive contact pad thereon and an electrically conductive connection terminal on the contact pad. The connection terminal includes an electrically conductive pillar structure and a solder layer that extends on the pillar structure and contacts a protruding portion of a sidewall of the pillar structure. The pillar structure can include a lower pillar layer, a diffusion barrier layer on the lower pillar layer and an upper pillar layer on the diffusion barrier layer. In some additional embodiments of the invention, the protruding portion of the sidewall of the pillar structure includes an outermost portion of an upper surface of the diffusion barrier layer. This can be achieved by making a width of the diffusion barrier layer greater than a width of the upper pillar layer when viewed in transverse cross-section.