Fan-out Interconnect Structure Eliminating Metallic Pillars
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Solution Overview
Problem
Conventional integrated circuit packaging technologies require additional metallic pillars for connecting redistribution layers to contact pads, increasing manufacturing costs and limiting the number of interconnect structures due to the need for these pillars.
Innovation Solution
The integration of a fan-out packaging method that eliminates the need for metallic pillars by using sloped sidewalls in redistribution layers directly connected to contact pads, allowing for a greater number of interconnect structures and reduced manufacturing costs through the use of polymer layers and sacrificial film layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic pillars are used to connect redistribution layers to contact pads, then electrical connection is achieved, but manufacturing cost increases and device complexity increases
Solution Approach 1:
The patent extracts and eliminates the metallic pillar component from the interconnect structure. Instead of using separate metallic pillars to connect redistribution layers to contact pads, the invention uses sloped sidewalls formed as integral parts of the redistribution layer, thereby removing the need for additional metallic pillar components and reducing overall device complexity while maintaining electrical connection functionality
Solution Approach 2:
The patent merges the connection function previously performed by separate metallic pillars into the redistribution layer structure itself. The sloped sidewalls of the redistribution layer directly provide the electrical connection to contact pads, combining what were previously separate components (redistribution layer and metallic pillars) into a single integrated structure
2Reliability
If metallic pillars are used for interconnect structures, then electrical connection is established, but the number of interconnect structures is limited due to manufacturing constraints
Solution Approach 1:
By extracting the metallic pillar requirement from the manufacturing process, the patent enables formation of redistribution layers with sloped sidewalls that can be created using standard semiconductor fabrication techniques such as spin coating and etching, thereby increasing the number of interconnect structures that can be formed without adding manufacturing complexity
Solution Approach 2:
The patent changes the geometric parameters of the redistribution layer by forming sloped sidewalls instead of vertical walls. This parameter change allows the redistribution layer to directly contact the contact pad surface at an angle, enabling electrical connection without metallic pillars and allowing for higher density interconnect structures
3Area of stationary object
If conventional packaging methods are used, then I/O pads can be redistributed to greater area, but manufacturing cost increases due to metallic pillars
Solution Approach 1:
The patent replaces expensive metallic pillars with a cost-effective polymer-based redistribution layer structure. The sloped sidewalls formed from polymer materials provide the necessary electrical connection function at lower material and manufacturing costs, making the fan-out packaging process more economically viable
Solution Approach 2:
By changing the sidewall angle parameter of the redistribution layer to be sloped rather than vertical, the patent enables direct contact with contact pads without requiring metallic pillars. This parameter change allows for area expansion of I/O pads while using lower-cost materials and processes
Data Source
AI summary
A method embodiment includes forming a sacrificial film layer over a top surface of a die, the die having a contact pad at the top surface. The die is attached to a carrier, and a molding compound is formed over the die and the sacrificial film layer. The molding compound extends along sidewalls of the die. The sacrificial film layer is exposed. The contact pad is exposed by removing at least a portion of the sacrificial film layer. A first polymer layer is formed over the die, and a redistribution layer (RDL) is formed over the die and electrically connects to the contact pad.