Hybrid Bonding Structure With Intermediate-CTE Buffer Layer
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Solution Overview
Problem
In 3D IC hybrid bonding, the difference in thermal expansion coefficients between metal and dielectric materials leads to thermal stress and cracking during the bonding process.
Innovation Solution
A buffer structure with a coefficient of thermal expansion ranging between that of the metal and dielectric materials is introduced to separate the conductive and dielectric structures, mitigating thermal stress and preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hybrid bonding is used to connect dies with small copper-to-copper connections, then interconnect density is improved, but thermal stress and cracking occur due to different coefficients of thermal expansion between metal and dielectric materials
Solution Approach 1:
A buffer layer is introduced as an intermediary between the metal interconnect and the dielectric material. This buffer layer has a coefficient of thermal expansion that is intermediate between those of the metal and dielectric, serving as a mediator that gradually transitions the thermal expansion properties and prevents direct stress concentration at the metal-dielectric interface, thereby preventing cracking while maintaining high interconnect density
Solution Approach 2:
The coefficient of thermal expansion parameter is changed by introducing a buffer layer with intermediate CTE properties. Instead of having a abrupt transition between metal and dielectric CTE values, the buffer layer creates a gradual parameter transition, reducing thermal stress and preventing cracks during thermal cycling while preserving the hybrid bonding structure's high density benefits
2Adaptability or versatility
If metal and dielectric materials are used in hybrid bonding, then bonding functionality is achieved, but cracks are induced during the bonding process due to CTE mismatch
Solution Approach 1:
The buffer layer acts as a mediator between the metal bonding pad and the dielectric structure, providing a transition zone that accommodates the CTE mismatch. This intermediary layer prevents direct stress transmission from the metal to the dielectric during thermal expansion and contraction, maintaining structural integrity while preserving the hybrid bonding functionality
Solution Approach 2:
The hybrid bonding structure is enhanced by creating a composite material system that includes metal, buffer layer, and dielectric components. This composite structure leverages the complementary properties of each material layer, where the buffer layer's intermediate CTE properties bridge the gap between metal and dielectric, ensuring both bonding functionality and crack resistance
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
The buffer structure effectively tolerates the thermal expansion differences, preventing cracks during hybrid bonding and ensuring the integrity of the semiconductor device structure.
Implementation Method 1
A coefficient of thermal expansion (CTE) of the buffer structure ranges between a CTE of the dielectric structure and a CTE of the conductive structure
Data Source
AI summary
A semiconductor device structure and method for manufacturing the same are provided. The semiconductor device structure includes a substrate, a dielectric structure, a pad, a conductive structure, and a buffer structure. The dielectric structure is disposed on the substrate. The pad is embedded in the dielectric structure. The conductive structure is disposed on the pad. The buffer structure is disposed on the pad and separates the conductive structure from the dielectric structure. A coefficient of thermal expansion (CTE) of the buffer structure ranges between a CTE of the dielectric structure and a CTE of the conductive structure.