Stacked Semiconductor Device with Elastic Barrier Pillar
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Solution Overview
Problem
The differences in coefficients of thermal expansion (CTE) between chips in multi-chip stacked semiconductor packages lead to detrimental defects due to temperature changes, causing delamination issues.
Innovation Solution
A stacked semiconductor device design that includes a conductive pillar with a barrier layer of different elastic modulus, encapsulated within the pillar, and a solder bump that electrically connects substrates, which helps absorb and disperse strain caused by temperature fluctuations, thereby reducing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-chip stacked package technology is used to reduce volume and improve electrical performance, then device integration and performance are improved, but delamination defects occur due to CTE differences between chips
Solution Approach 1:
The patent changes the physical parameter of the conductive pillar by introducing a barrier layer with different elastic modulus than the conductive pillar material. This creates a composite structure where the barrier layer absorbs and disperses thermal expansion strain, preventing delamination while maintaining the integrated stacked package structure.
Solution Approach 2:
The patent employs composite material structure by combining the conductive pillar material with a barrier layer having different elastic modulus. This composite structure within the conductive pillar allows it to accommodate differential thermal expansion between chips, thereby preventing delamination while maintaining electrical connectivity in the stacked package.
2Adaptability or versatility
If chips with different CTE are stacked together to achieve multi-functionality, then device functionality is improved, but strain accumulation occurs during temperature changes
Solution Approach 1:
The patent introduces a barrier layer with specifically different elastic modulus parameter compared to the conductive pillar material. This parameter differentiation allows the barrier layer to act as a strain buffer, absorbing thermal expansion differences and preventing strain accumulation that would otherwise compromise the stability of the multi-functional stacked device.
3Ease of manufacture
If conventional conductive pillars are used without barrier layers, then manufacturing process is simple, but delamination occurs under thermal stress
Solution Approach 1:
The patent applies the nesting principle by placing the barrier layer inside the conductive pillar structure. The barrier layer is nested within the conductive pillar material, creating a concentric composite structure that maintains manufacturing simplicity while providing thermal stress resistance through the elastic modulus difference between the nested layers.
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 solution effectively reduces delamination between substrates by absorbing and dispersing strain from temperature changes, enhancing the reliability and stability of multi-chip stacked packages.
Implementation Method 1
an elastic modulus of the first barrier layer is different from an elastic modulus of the conductive pillar
Data Source
AI summary
A stacked semiconductor device is provided in the present invention. The stacked semiconductor device includes a first substrate and a second substrate. A first conductive pad is disposed on the first substrate. A conductive pillar contacts the first conductive pad. At least one first barrier layer is disposed inside the conductive pillar. The conductive pillar encapsulates the first barrier layer. The elastic modulus of the first barrier layer is different from the elastic modulus of conductive pillar. A second conductive pad is disposed on the second substrate. A solder bump is disposed between the first substrate and the second substrate. The solder bump electrically connects to the conductive pillar. The conductive pillar can optionally include a truncated cone.