RDL-Last Package Structure for Fine-Pitch Routing and Heat Dissipation
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Solution Overview
Problem
Conventional RDL-last processes face challenges in forming fine-pitch redistribution lines due to coefficient of thermal expansion (CTE) mismatch and stress issues, especially when polymer layers are used, leading to structural integrity problems and poor heat dissipation in complex integrated circuit packages.
Innovation Solution
The use of oxide-based materials and damascene processes to form fine-pitch redistribution lines without polymer layers, combined with metal-to-metal bonding and heat spreaders for improved thermal conductivity and stress management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer materials are used in package construction, then ease of manufacture is improved, but thermal expansion mismatch increases causing structural integrity problems
Solution Approach 1:
The patent removes polymer materials from the package construction entirely, extracting the harmful element that causes thermal expansion mismatch. This is achieved by using oxide-based dielectric materials instead of polymers for RDL formation and gap filling, eliminating the source of thermal stress while maintaining manufacturability through standard semiconductor processing techniques.
Solution Approach 2:
The patent changes the material parameter from polymer to oxide-based dielectric material, fundamentally altering the thermal expansion characteristics of the package structure. This parameter change ensures that all materials have compatible thermal expansion coefficients, eliminating thermal mismatch issues while allowing continued use of established manufacturing processes.
2Manufacturing precision
If fine-pitch RDLs are formed using conventional processes, then routing density is improved, but thermal stress from polymer materials causes formation failures
Solution Approach 1:
The patent changes the material parameter from polymer to oxide-based dielectric material, fundamentally altering the thermal expansion characteristics of the package structure. This parameter change ensures that all materials have compatible thermal expansion coefficients, eliminating thermal mismatch issues while allowing continued use of established manufacturing processes.
Solution Approach 2:
The patent copies the successful RDL formation methodology from conventional processes but adapts it to work with oxide-based materials instead of polymers. The same damascene process steps, etching patterns, and metallization techniques are used, but the dielectric material substitution enables these processes to complete successfully without thermal stress-induced failures.
3Temperature
If polymer layers are eliminated to reduce thermal mismatch, then heat dissipation is improved, but manufacturing complexity increases
Solution Approach 1:
The oxide-based dielectric material serves multiple functions simultaneously: it acts as the RDL dielectric layer, provides gap filling between device dies, and serves as the encapsulation material. This multi-functionality eliminates the need for separate polymer layers while maintaining all necessary package functions, thereby improving heat dissipation without significantly increasing manufacturing complexity.
Solution Approach 2:
The patent merges the functions of multiple polymer layers (RDL dielectric, gap filler, encapsulation) into a single oxide-based dielectric material system. This consolidation reduces the number of material interfaces and process steps required, simplifying the overall manufacturing process while eliminating thermal mismatch issues associated with polymer materials.
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 thin, high-density fine-pitch redistribution lines with enhanced structural integrity and efficient heat dissipation, facilitating better package performance and reliability in complex integrated circuits.
Implementation Method 1
A heat spreader may be attached to the top surfaces of the device dies in order to dissipate the heat generated in the device dies
Implementation Method 2
thermal interface materials
Data Source
AI summary
A method includes bonding a first device die and a second device die to a substrate, and filling a gap between the first device die and the second device die with a gap-filling material. A top portion of the gap-filling material covers the first device die and the second device die. Vias are formed to penetrate through the top portion of the gap-filling material. The vias are electrically coupled to the first device die and the second device die. The method further includes forming redistribution lines over the gap-filling material using damascene processes, and forming electrical connectors over and electrically coupling to the redistribution lines.