Pull-In Planarization Layer for UBM Adhesion in Semiconductor Packaging
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Solution Overview
Problem
The existing semiconductor packaging processes face challenges with delamination between the polymer planarization layer and the passivation layer, which affects the reliability and durability of the redistribution lines and Under-Bump-Metallurgy (UBM) connections.
Innovation Solution
A method and structure where a polymer planarization layer is formed with extensions into the openings of the passivation layer, creating a non-planar interface that acts as an anchor to reduce delamination, and a UBM is formed to extend into these openings for electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a planarization layer is formed over the passivation layer, then the surface planarity is improved, but delamination occurs between the layers
Solution Approach 1:
The patent transitions from a planar interface to a three-dimensional interlocking interface by forming openings in the passivation layer and extending the planarization layer into these openings. This dimensional change creates mechanical anchoring that prevents delamination while preserving surface planarity where needed.
Solution Approach 2:
The planarization layer is nested into the openings of the passivation layer, creating a interlocked structure where one layer is partially contained within the other. This nesting provides mechanical interlocking that enhances adhesion between the layers.
2Ease of manufacture
If the planarization layer is made planar, then subsequent processing is simplified, but electrical connectivity to the metal pad is compromised
Solution Approach 1:
The patent segments the planarization layer into two functional zones: a planar top surface for simplified processing and a non-planar portion extending into openings for electrical connectivity. This segmentation allows each zone to fulfill its specific function optimally.
Solution Approach 2:
The planarization layer exhibits different properties in different locations: it is planar at the top surface for processing ease, but extends into openings at specific locations to provide electrical connectivity. This local differentiation resolves the contradiction between planarity and connectivity.
3Reliability
If a UBM is formed to connect to the metal pad, then electrical connectivity is improved, but the structure becomes more complex
Solution Approach 1:
The planarization layer serves multiple functions: it provides surface planarity for processing, acts as a mechanical anchor to prevent delamination, and extends into openings to provide electrical connectivity to the metal pad. This multi-functionality reduces the need for separate dedicated structures.
Solution Approach 2:
The patent merges the electrical connection function into the planarization layer itself by extending it into the openings to contact the metal pad. This consolidation eliminates the need for a separate connection structure, reducing overall device complexity.
Data Source
AI summary
A method includes forming a patterned mask comprising a first opening, plating a conductive feature in the first opening, depositing a passivation layer on a sidewall and a top surface of the conductive feature, and patterning the passivation layer to form a second opening in the passivation layer. The passivation layer has sidewalls facing the second opening. A planarization layer is dispensed on the passivation layer. The planarization layer is patterned to form a third opening. After the planarization layer is patterned, a portion of the planarization layer is located in the second opening and covers the sidewalls of the passivation layer. An Under-Bump Metallurgy (UBM) is formed to extend into the third opening.