Stress Redistribution Layer for IC Mechanical Protection
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Solution Overview
Problem
Current integrated circuit technologies face challenges in accommodating high-speed devices exceeding one TeraHertz, with limitations in assembly, cooling, reliability, and cost-effectiveness, particularly in miniature form factors and complex microprocessor systems, leading to increased production risks and costs.
Innovation Solution
The integration of a stress redistribution layer in the integrated circuit system, involving a substrate with a transistor and metallization layer, a metal pad, a passivation layer, and a routing trace that is larger than the metal pad, with a bump connected to the routing trace rather than the metal pad, allowing for mechanical protection and efficient manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bump is formed directly on a metal pad in conventional integrated circuit structures, then the electrical connection is simple and direct, but the mechanical stress concentrates on the metal pad and underlying transistor elements, reducing reliability
Solution Approach 1:
The patent introduces a stress redistribution layer as an intermediary component between the bump and the metal pad. This layer acts as a mediator that receives mechanical stress from the bump and redistributes it over a larger area, preventing stress concentration on the metal pad and underlying transistor elements. The stress redistribution layer has a larger surface area than the metal pad, allowing it to disperse applied forces more effectively and improve overall structural reliability.
2Strength
If the routing trace is made substantially larger than the metal pad to provide stress redistribution, then mechanical protection is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The stress redistribution layer is formed prior to bump formation, allowing the larger structural element to be established before the smaller precision component (bump) is added. This preliminary action enables the manufacturing process to work with the larger, more tolerant dimensions first, then add the smaller precision elements afterward, potentially reducing overall manufacturing precision requirements.
3Reliability
If additional layers are added to provide stress redistribution and mechanical protection, then reliability and mechanical strength are improved, but the device complexity and production cost increase
Solution Approach 1:
The stress redistribution layer serves multiple functions simultaneously: it provides mechanical stress redistribution, acts as a structural support element, and can be integrated with existing routing trace layers. By making this layer multi-functional, the patent reduces the need for separate dedicated stress management components, thereby limiting the increase in overall device complexity while still achieving improved reliability.
4Reliability
If the routing trace is not electrically insulated by a subsequent layer to maintain electrical connection, then electrical conductivity is maintained, but mechanical protection is reduced
Solution Approach 1:
The patent applies different properties to different regions: the stress redistribution layer has a larger surface area for mechanical stress distribution, while the routing trace maintains electrical connectivity. The local quality of each layer is optimized for its primary function - the stress redistribution layer for mechanical protection and the routing trace for electrical connection - allowing both requirements to be satisfied simultaneously in different locations of the structure.
Data Source
AI summary
A method of manufacture of an integrated circuit system includes: providing a substrate having a transistor and a metallization layer; forming a metal pad in direct contact with the metallization layer of the substrate; forming a passivation layer in direct contact with the metal pad and covering the substrate; forming a routing trace above the passivation layer in direct contact with the metal pad, and the routing trace is substantially larger than the metal pad, and the routing trace is not electrically insulated by a subsequent layer; and forming a bump connected to the metal pad with the routing trace.