Bonding Interface Recesses for Particle-Induced Void Control
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Solution Overview
Problem
Conventional direct-bonding processes in microelectronics often result in bonding voids due to stray particles and contaminants, which weaken the bond and compromise electrical conductivity and assembly reliability, especially in ultrafine electrical leads used in high-performance applications like HBM2 memory and SerDes signaling.
Innovation Solution
The introduction of predesigned recesses, sinks, or cavities in the bonding interface to trap contaminants and gaseous byproducts, preventing the formation of voids and arresting crack propagation, thereby enhancing bond integrity and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional direct-bonding processes are used to join surfaces, then bonding speed and simplicity are maintained, but bonding voids form due to stray particles and contaminants, weakening bond strength and compromising reliability
Solution Approach 1:
The patent applies preliminary action by forming recesses in the bonding surfaces before the direct-bonding process. These pre-formed recesses serve as predetermined traps that capture stray particles and contaminants during bonding, preventing them from creating voids in the bond interface. This preliminary structural modification ensures that when bonding occurs, contaminants are already contained in designated areas rather than interfering with bond formation.
Solution Approach 2:
The patent converts the harmful effect of stray particles and contaminants into a beneficial outcome by designing recesses that deliberately trap these contaminants. Instead of allowing particles to randomly create voids that weaken bonds, the recesses guide and contain particles in predetermined locations, effectively converting the harmful presence of contaminants into a controlled situation that preserves bond integrity in the critical bonding areas.
2Manufacturing precision
If ultra-flat bonding surfaces are created through CMP to improve bonding quality, then surface flatness and bonding uniformity are enhanced, but small particles cause disproportionately large bonding voids
Solution Approach 1:
The patent applies local quality by creating localized recesses in specific areas of the bonding surface rather than modifying the entire surface uniformly. These localized recesses are strategically positioned to trap particles that would otherwise create voids in critical bonding areas. This approach maintains the ultra-flat quality of the overall bonding surface while introducing local variations that provide particle containment functionality.
Solution Approach 2:
The recesses act as intermediary structures between the ultra-flat bonding surface and the stray particles. Instead of allowing particles to directly contact and create voids in the bond interface, the recesses serve as intermediate containment zones that capture and isolate particles, preventing their harmful interaction with the primary bonding area while preserving the flatness of the main bonding surface.
3Object-affected harmful factors
If bonding surfaces are cleaned thoroughly to remove contaminants, then particle contamination is reduced, but cleaning residues and processing time increase
Solution Approach 1:
The patent converts the potentially harmful cleaning residues into a manageable situation by providing recesses that can trap any remaining contaminants after cleaning. Rather than requiring absolutely complete removal of all contaminants (which would extend cleaning time), the recesses provide a safety net that captures any residues or particles that escape the cleaning process, ensuring bond quality without requiring excessively long cleaning cycles.
Solution Approach 2:
The pre-formed recesses provide preliminary particle containment capability before bonding occurs. This means that even if cleaning is not perfectly thorough, the recesses are already in place to capture any remaining contaminants, reducing the need for extended cleaning processes and allowing optimized cleaning parameters that balance effectiveness with processing time.
4Strength
If annealing is performed to improve bond quality, then bond strength is enhanced, but gaseous byproducts are trapped, creating voids at the bonding interface
Solution Approach 1:
The patent converts the harmful gaseous byproducts generated during annealing into a controlled situation by providing recesses that trap these gases. The annealing process continues to be performed to achieve the necessary bond strength, but the recesses serve as gas traps that prevent the byproducts from accumulating in the bond interface and creating voids. This allows the beneficial strengthening effect of annealing while mitigating its harmful gas-generation side effect.
Data Source
AI summary
Structures and techniques provide bond enhancement in microelectronics by trapping contaminants and byproducts during bonding processes, and arresting cracks. Example bonding surfaces are provided with recesses, sinks, traps, or cavities to capture small particles and gaseous byproducts of bonding that would otherwise create detrimental voids between microscale surfaces being joined, and to arrest cracks. Such random voids would compromise bond integrity and electrical conductivity of interconnects being bonded. In example systems, a predesigned recess space or predesigned pattern of recesses placed in the bonding interface captures particles and gases, reducing the formation of random voids, thereby improving and protecting the bond as it forms. The recess space or pattern of recesses may be placed where particles collect on the bonding surface, through example methods of determining where mobilized particles move during bond wave propagation. A recess may be repeated in a stepped reticule pattern at the wafer level, for example, or placed by an aligner or alignment process.