Copper Bond Pads with (111) Orientation for Low-Temperature Direct Bonding
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Solution Overview
Problem
In the formation of integrated circuits, existing technologies face challenges in achieving strong and reliable bonding between metal pads and dielectric layers, particularly in achieving low-resistance connections and maintaining co-planarity, which affects the quality and efficiency of interconnect structures.
Innovation Solution
The method involves forming bond pads with a preferred copper orientation of (111) surface orientation, which facilitates metal-to-metal direct bonding and fusion bonding, using a hybrid approach that combines dielectric barrier layers and silicon-containing dielectric materials to enhance bonding strength and reduce resistance, and includes the use of dummy bond pads to improve co-planarity and pattern-loading effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional bonding methods are used between metal pads and dielectric layers, then the bonding process requires high annealing temperatures and long times, but the bonding strength and reliability are insufficient
Solution Approach 1:
The patent changes the crystallographic orientation parameter of the copper bond pad surface to (111) orientation, which fundamentally alters the bonding characteristics. This parameter change enables strong bonding at lower annealing temperatures and shorter times, directly resolving the contradiction between bonding strength and annealing temperature requirements
Solution Approach 2:
The patent employs a composite structure consisting of copper bond pads with specific (111) orientation combined with dielectric layers. This composite material approach creates favorable bonding interfaces that achieve high bonding strength without requiring extreme annealing conditions, thus resolving the temperature-strength contradiction
2Reliability
If copper bond pads are formed with (111) surface orientation to facilitate direct bonding, then bonding quality improves, but the manufacturing process complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-forming copper bond pads with controlled (111) surface orientation before the bonding process. This preliminary preparation of the surface structure enables subsequent low-temperature, high-quality bonding, and when integrated into existing manufacturing flows, the added complexity is managed through process optimization
Solution Approach 2:
By controlling the crystallographic orientation parameter of the copper surface during deposition or annealing, the patent achieves favorable (111) orientation that promotes direct bonding. This parameter control, while adding some manufacturing complexity, significantly improves bonding reliability and quality
3Manufacturing precision
If dummy bond pads are added to improve co-planarity and reduce pattern-loading effects, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent introduces dummy bond pads as intermediary structures that do not perform electrical functions but serve as mechanical and structural placeholders. These dummy pads act as mediators to maintain co-planarity across the substrate and reduce pattern-loading effects during processing, thereby improving manufacturing precision with minimal impact on device functionality
Solution Approach 2:
The patent segments the bond pad structure into functional bond pads and dummy bond pads. This segmentation allows the dummy pads to independently fulfill the co-planarity and pattern-loading reduction functions without interfering with the electrical performance of the functional bond pads, thus improving manufacturing precision while managing structural 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 results in stronger bonds with lower annealing temperatures and shorter times, improved bonding quality, reduced resistance, and the ability to achieve fine-pitch I/O applications, while maintaining the electrical functionality of bond pads.
Implementation Method 1
bond pads with a preferred copper orientation of (111) surface orientation, which facilitates metal-to-metal direct bonding and fusion bonding
Implementation Method 2
metal-to-metal direct bonding and fusion bonding
Implementation Method 3
stronger bonds with lower annealing temperatures and shorter times
Data Source
AI summary
A method includes forming a first conductive feature and a second conductive feature, forming a metal pad over and electrically connected to the first conductive feature, and forming a passivation layer covering edge portions of the metal pad, with a center portion of a top surface of the metal pad exposed through an opening in the metal pad. A first dielectric layer is formed to cover the metal pad and the passivation layer. A bond pad is formed over the first dielectric layer, and the bond pad is electrically coupled to the second conductive feature. A second dielectric layer is deposited to encircle the bond pad. A planarization is performed to level a top surface of the second dielectric layer with the bond pad. At a time after the planarization is performed, an entirety of the top surface of the metal pad is in contact with dielectric materials.