Bond Pad Via Structure for Thermal Expansion Mismatch in Cu-Cu Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the semiconductor industry, particularly at the 5 nanometer node and below, there is a challenge in minimizing protrusions during bonding processes of semiconductor devices due to mismatches in coefficients of thermal expansion, which affects the bonding yield and reliability of copper-copper bonds in stacked semiconductor devices.
Innovation Solution
Embedding bond pad vias within or through bond pads to modulate undesirable protrusions, utilizing techniques such as forming concentric circular or segmented structures to align with the thermal expansion mismatch, thereby reducing protrusions and enhancing bonding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding processes are used for copper-copper bonds in stacked semiconductor devices, then the bonding process can be completed, but thermal expansion mismatch causes protrusions that reduce bonding yield and reliability
Solution Approach 1:
The bonding interface is segmented into multiple regions: a first region with a first material (e.g., copper) and a second region with a second material (e.g., copper alloy or different composition) having different coefficients of thermal expansion. This segmentation allows different portions of the bonding interface to respond differently to thermal expansion, compensating for mismatch and preventing protrusions that would otherwise reduce bonding yield and reliability.
Solution Approach 2:
Different materials with specific thermal expansion properties are placed in specific locations at the bonding interface. The first material is positioned in a first region while the second material with different thermal expansion characteristics is positioned in a second region. This local differentiation of material properties enables targeted compensation for thermal expansion mismatch in different areas of the bonding interface, thereby improving overall bonding reliability.
2Manufacturing precision
If single-material bonding interfaces are used, then the bonding process is simpler, but thermal expansion mismatch reduces bonding precision and reliability
Solution Approach 1:
The bonding interface is divided into distinct first and second regions with different materials. This segmentation enables precise control over thermal expansion behavior in different areas, improving bonding precision by preventing protrusions. The added regional complexity is offset by the systematic approach to material selection and placement.
Solution Approach 2:
The bonding interface uses composite material construction with a first material in a first region and a second material in a second region. These composite materials are specifically selected to have different coefficients of thermal expansion, enabling the interface to compensate for thermal effects and maintain high bonding precision during thermal cycling, while the composite structure itself becomes the solution rather than an added complexity.
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 improves bonding yield by minimizing thermal expansion-induced protrusions, especially at elevated temperatures, leading to more reliable copper-copper bonds in system-on-integrated circuit systems.
Implementation Method 1
mismatches in coefficients of thermal expansion, which affects the bonding yield and reliability of copper-copper bonds
Data Source
AI summary
Semiconductor devices and methods of manufacture are presented which form metallization layers over a semiconductor substrate; form a first pad over the metallization layers; deposit one or more passivation layers over the first pad; and form a first bond pad via through the one or more passivation layers and at least partially through the first pad.