Advancements in Hybrid Bonding Technology on Intel Process

Table of Contents

1. Introduction to Hybrid Bonding
2. Need for Pitch Scaling and Hybrid Bonding
3. Design Benefits and Considerations of Hybrid Bonding
4. Process and Assembly Optimizations for High-Quality Bonding
5. Manufacturing Results and Future Considerations
6. Comparison: Solder Attach vs Hybrid Bonding
7. Two Types of Hybrid Bonding Assembly: Wafer-to-wafer and Die-to-wafer
8. Design Challenges and Impacts on Power and Signal Integrity
9. Process Optimization Considerations and Results
10. Assembly Considerations: Placement Accuracy, Cleanliness, and testing
11. Conclusion and Future Considerations

Introduction to Hybrid Bonding

In the field of technology development at Intel Corporation, there has been significant research on enabling hybrid bonding on Intel processes. This article aims to Present a comprehensive overview of hybrid bonding, including its need, design benefits, process optimization considerations, assembly challenges, and manufacturing results. Hybrid bonding is a Novel assembly technology that allows for the combination of multiple dies optimized for different functionalities while maintaining high performance. By providing higher interconnect densities, reduced capacitance, and improved signal integrity, hybrid bonding offers the potential for significant advancements in packaging trends and heterogeneous integration technologies.

Need for Pitch Scaling and Hybrid Bonding

To meet the increasing demand for more functionality within a Package, there is a need for pitch scaling in current packaging trends. Traditional monolithic die architectures have limitations in enabling this Scale of functionality. As a result, the shift towards 2D and 3D integration architectures, such as multi-chip packaging and through-silicon interposers, has become essential. However, the incumbent technology of solder has limitations in interconnect density, leading to higher overheads. To overcome these limitations, hybrid bonding technology is introduced, which supports pitch scaling below 10 microns and provides significantly higher interconnect densities compared to solder.

Design Benefits and Considerations of Hybrid Bonding

Hybrid bonding offers several design benefits that make it a compelling choice for advanced packaging. With interconnect densities comparable to undivered densities, hybrid bonding reduces area overhead and enables more than 10 times higher density than solder. The resulting smaller parasitics lead to lower power consumption and reduced latency. In addition, hybrid bonding allows for better signal integrity in side-to-side connections, simplifying circuit designs. However, switching to hybrid bonding also introduces challenges, such as complex processes, stringent cleanliness requirements, and certain test challenges. Design optimizations are necessary to optimize power and signal integrity and minimize the impact on inductor quality factors.

Process and Assembly Optimizations for High-Quality Bonding

The successful implementation of hybrid bonding hinges on several crucial process and assembly optimizations. One significant process optimization is controlling the bowing of bonding layers to ensure continued processing. Furthermore, planarization through chemical-mechanical polishing (CMP) plays an essential role in achieving the required surface flatness and smoothness for bonding. These optimizations enable the formation of robust dielectric-to-dielectric transition and metal-to-metal interdiffusion, ensuring high-quality bonding.

Manufacturing Results and Future Considerations

Extensive testing and verification through the fabrication of test chips have been conducted to assess the efficacy of hybrid bonding. These test chips include passive and active structures, allowing for the evaluation of bond strength, electrical performance, and system yield. The results demonstrate successful bonding and good electrical results, showcasing the potential of hybrid bonding technology. Looking to the future, the widespread adoption of hybrid bonding requires interoperability specifications and the consideration of extended triplet ecosystems.

Comparison: Solder Attach vs Hybrid Bonding

A comparison between solder attach and hybrid bonding sheds light on the advantages of the latter. While solder attach introduces limitations in interconnect density and may result in density electromigration challenges, hybrid bonding overcomes these limitations. Hybrid bonding removes the interface between two dies, reducing area overhead and eliminating density electromigration concerns. However, hybrid bonding comes with its own set of challenges, such as complex processes, cleanliness requirements, and test challenges. Despite these challenges, hybrid bonding offers a path towards near monolithic performance and supports advanced heterogeneous integration technologies.

Two Types of Hybrid Bonding Assembly: Wafer-to-wafer and Die-to-wafer

Hybrid bonding assembly can occur in two major forms: wafer-to-wafer and die-to-wafer. In wafer-to-wafer bonding, two wafers are manufactured and bonded before dicing the stacked dies for testing. This approach is more mature and enables finer pitches. However, it has limitations, such as requiring identical-sized dies and cumulative yield impact. On the other HAND, die-to-wafer bonding, preferred for high-performance computing, focuses on attaching good dies from one wafer to the base wafer after individual die testing. Although less mature, die-to-wafer bonding addresses the limitations of wafer-to-wafer bonding and promises rapid improvement.

Design Challenges and Impacts on Power and Signal Integrity

The adoption of hybrid bonding necessitates addressing design challenges and assessing their impacts on power and signal integrity. The transition from solder to hybrid bonding affects interconnect parasitics and their implications. While hybrid bonding reduces the area and distance between dies, improving resistance and capacitance, it leads to increased coupling between stacked dies. Design considerations are crucial to minimize the impact on inductor quality factors and ensure optimal performance. Balancing the requirements of hybrid bonding with surface topography, current crowding effects, and thermo-mechanical considerations presents further design considerations.

Process Optimization Considerations and Results

Process optimization plays a critical role in ensuring the success of hybrid bonding. Key considerations include controlling wafer bowing, achieving planarization through CMP, and surface topography. By optimizing stack materials, deposition parameters, and CMP techniques, the challenges associated with bonding layer thickness and surface roughness have been overcome. The resulting improvements in planarity, metal pad recess, and dielectric smoothness enable successful bonding and promote high-quality interfaces.

Assembly Considerations: Placement Accuracy, Cleanliness, and Testing

The assembly stage of hybrid bonding requires meticulous attention to placement accuracy, cleanliness, and testing. Achieving accurate placement of dies is crucial for fine pitch bonding. Design optimizations, including visibility and contrast of alignment fiducials, enable high alignment accuracy. Furthermore, tool optimizations ensure fast throughput without compromising alignment precision. Maintaining cleanliness during assembly is critical to prevent particle-induced bond failures. Class 100 assembly floor cleaning, surface protection, and tool optimizations are employed to achieve extreme cleanliness. Finally, testing coverage must be comprehensive to ensure good final system yield, especially in systems with a large number of dies.

Conclusion and Future Considerations

Hybrid bonding technology presents an exciting development in packaging trends, offering the potential for near monolithic interconnect and significant advancements in heterogeneous integration technologies. While there are challenges to overcome, such as cleanliness requirements and interoperability specifications, the benefits in terms of interconnect density, power, and signal integrity make hybrid bonding a promising choice. Continued research and optimization efforts will further enhance the performance and adoption of hybrid bonding in future computing architectures.

Future Consideration:

One future consideration for hybrid bonding technology is the extension of current triplet ecosystems. Due to the additional interoperability specifications required for hybrid bonding, such as pad Dimensions, surface roughness, and planarity, collaboration between different foundries becomes crucial. The establishment of common standards and protocols will enable the assembly of triplets from different sources, facilitating the development of advanced heterogeneous integration technologies.

FAQ

Q: What are the advantages of hybrid bonding compared to solder attach? A: Hybrid bonding offers higher interconnect densities, reduced area overhead, and improved signal integrity compared to solder attach. It enables more than 10 times higher density than solder and lower capacitance for stacked die configurations. Moreover, hybrid bonding eliminates certain limitations associated with solder, such as density electromigration challenges and thermomechanical impacts on final structures.

Q: What are the two types of hybrid bonding assembly? A: The two types of hybrid bonding assembly are wafer-to-wafer bonding and die-to-wafer bonding. Wafer-to-wafer bonding involves manufacturing and bonding two wafers before dicing the stacked dies for testing, while die-to-wafer bonding focuses on attaching good dies from one wafer to the base wafer after individual die testing.

Q: How does hybrid bonding impact power and signal integrity? A: Hybrid bonding reduces interconnect parasitics, resulting in lower power consumption and reduced latency. However, it introduces increased coupling between stacked dies, which requires design optimizations to mitigate the impact on power and signal integrity. Additionally, hybrid bonding can affect the quality factors of on-die inductors and transformers, requiring specific design rule changes to maintain optimal performance.

Q: What factors are crucial for successful hybrid bonding? A: Successful hybrid bonding relies on several factors, including precise placement accuracy, extreme cleanliness, and comprehensive testing. High alignment accuracy is achieved through design optimizations and tool improvements. Cleanliness is maintained through class 100 assembly floor cleaning, surface protection, and optimized processes. Comprehensive testing coverage is necessary to ensure good final system yield, especially when dealing with a large number of dies.

Q: What are some future considerations for hybrid bonding? A: One future consideration is the extension of current triplet ecosystems to accommodate hybrid bonding. This entails defining interoperability specifications and standards for pad dimensions, surface roughness, and planarity. Collaboration between different foundries will be essential to enable the assembly of triplets from various sources, fueling the development of advanced heterogeneous integration technologies.

Resources

1. Intel Corporation: https://www.intel.com
2. Reference: [Add reference title and link here]