Under-Bump Metallization Void Structure for Delamination Resistance
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Solution Overview
Problem
Existing semiconductor device under-bump metallization (UBM) formation techniques face challenges such as non-uniform material deposition, mechanical stresses, and delamination issues, particularly in corner regions and edge areas, leading to reliability concerns like current crowding, inefficient cooling, and weak bonding between metallic and polymeric layers.
Innovation Solution
A method involving the formation of a first layer with a top surface extending in multiple directions, followed by the deposition of subsequent layers and a void creation to expose the surface, allowing for efficient removal of UBM portions using an adhesive film, which reduces mechanical stresses and improves bonding by skipping certain processing steps that increase adhesion, thereby enhancing processing speed and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional UBM formation techniques are used, then processing is simpler, but delamination occurs and reliability decreases
Solution Approach 1:
The patent applies preliminary action by forming the void in the second layer before depositing the UBM layers. This pre-positioned void serves as a release mechanism that prevents delamination during subsequent processing steps, allowing the UBM structure to be formed with increased thickness without bonding failures.
Solution Approach 2:
The patent segments the UBM structure into multiple distinct layers (third layer, fourth layer, fifth layer) with different materials and functions. This segmentation allows each layer to be optimized for specific properties (adhesion, diffusion barrier, conductivity) and enables the structure to accommodate thermal expansion differences, preventing delamination.
2Strength
If UBM thickness is increased to improve bonding, then bonding strength increases, but mechanical stresses increase causing delamination
Solution Approach 1:
The patent implements beforehand cushioning by incorporating the void structure within the UBM layers before final bonding. This void acts as a stress relief mechanism that absorbs mechanical stresses generated by thermal expansion mismatches and bonding forces, allowing increased UBM thickness without causing delamination.
Solution Approach 2:
The patent applies local quality by creating regions of different material properties within the UBM structure. The void regions provide stress relief while the solid metal layers provide bonding strength, allowing the structure to have increased overall thickness with localized stress management capabilities.
3Productivity
If adhesive film processing is used to remove UBM portions, then processing speed increases, but material consumption increases
Solution Approach 1:
The patent applies the extraction principle by using an adhesive film to selectively remove only the portions of the UBM layers that are not needed for the final device function. The void structure enables clean separation and removal of excess material, improving processing speed while minimizing waste through precise targeted removal.
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 approach enables the formation of UBM structures with increased thickness without delamination, improves processing efficiency, and reduces material consumption, addressing the reliability issues and manufacturing challenges associated with corner and edge regions.
Implementation Method 1
performing a material removal operation, where the material removal operation lifts portions of the one or more layers formed on the top surface of the second layer off of the top surface
Data Source
AI summary
Methods, systems, and devices for semiconductor manufacturing are described. One such method includes forming a first layer comprising a first material. A top surface of the first layer extends along a first direction and a second direction. In some cases, the method includes forming, on at least the top surface of the first layer, a second layer comprising a second material, and forming a void in the second layer. Forming the void may expose a portion of the top surface of the first layer. In some cases, the method may include forming one or more layers on a top surface of the second layer and on the exposed portion of the top surface of the first layer. The method may also include performing a material removal operation that lifts portions of the one or more layers formed on the top surface of the second layer off of the top surface.