With the rapid development of high-performance computing (HPC), artificial intelligence (AI), and big data analysis, advanced packaging technologies such as CoWoS (Chip-on-Wafer-on-Substrate) are becoming increasingly important for enhancing computing performance and efficiency. This article will cover the fundamental principles of CoWoS technology, its application areas, market prospects, and the impact of this technology on the semiconductor industry.
Fundamental Principles of CoWoS Technology
CoWoS technology, introduced by TSMC, is an advanced packaging technology that involves directly packaging multiple processor chips (such as SoCs) on a silicon interposer. These chips are vertically connected through Through-Silicon Vias (TSVs) on the interposer, forming a highly integrated system package. This silicon interposer is then integrated onto a substrate (such as a PCB). This method significantly shortens the connection distance between chips, enhancing data transfer speed, reducing latency, and improving overall system performance.
Specifically, the key to CoWoS technology lies in its highly integrated packaging method. By integrating multiple chips in a single package, CoWoS offers higher data transfer rates and lower power consumption, making it particularly suitable for high-performance, high-efficiency computing applications such as HPC and AI.
Introduction to CoWoS-S, CoWoS-R, and CoWoS-L Technologies
TSMC's CoWoS technology platform includes CoWoS-S, CoWoS-R, and CoWoS-L, each optimized for different high-performance computing needs. These technologies use advanced packaging and interconnect methods to significantly enhance system performance and integration density.
CoWoS-S：
CoWoS-S is TSMC's initial CoWoS technology, utilizing a silicon interposer for system-level integration. This technology allows the integration of multiple interposers larger than 2x photomask size (approximately 1700 mm²) and supports up to four HBM2/HBM2E memory stacks. This packaging method significantly enhances the performance and integration density for high-performance computing applications.
CoWoS-R：
CoWoS-R is part of TSMC's CoWoS technology platform, designed to enhance system integration and performance. It combines TSMC's InFO technology with Redistribution Layer (RDL) interposers for chip connections.
RDL Interposer： The Re-Distribution Layer (RDL) is used for redistributing electrical connections between the chip and the package substrate. RDL is typically made of polymer materials and copper lines, which redistribute the input/output (I/O) from the chip to the package contact points. This provides excellent mechanical flexibility and electrical performance, enabling it to handle high-density interconnections and ensure signal integrity.
C4 Joints： These joints connect different chips and high-bandwidth memory (HBM) through the RDL layer, providing stable and reliable electrical connections.
CoWoS-L：
CoWoS-L is a chip-last packaging technology within TSMC's CoWoS platform. It combines the advantages of CoWoS-S and InFO technologies, using Local Silicon Interconnect (LSI) chips for chip-to-chip interconnections and Redistribution Layer (RDL) for power and signal transmission.
Local Silicon Interconnect (LSI): LSI chips are used for high-density interconnections between chips, enabling efficient data transfer and low latency.
Redistribution Layer (RDL): The RDL layer is responsible for power and signal transmission, providing stable and reliable electrical connections.。
Packaging Structure: Starting with an interposer of 1.5x photomask size, it gradually scales up to integrate more chips, adapting to various application needs.
CoWoS Technology Introduction and Discussion
Multi-Chip Integration
CoWoS (Chip-on-Wafer-on-Substrate) technology integrates multiple logic and memory chips on a single substrate, significantly reducing the inter-chip connection distance. This technology achieves higher computational power and lower power consumption through the following methods:
Silicon Interposer: Using a silicon interposer for chip-to-chip interconnection, the interposer features thousands to tens of thousands of Through-Silicon Vias (TSVs) that enable high-density vertical interconnections, greatly reducing the distance between chips.
High-Bandwidth Memory (HBM): High-bandwidth memory (such as HBM2 or HBM2E) is directly packaged on the silicon interposer and placed adjacent to logic chips. This layout reduces the physical distance for data transmission between memory and processors, improving data transfer rates and reducing latency.
Redistribution Layer (RDL) and Local Silicon Interconnect (LSI): RDL and LSI technologies further enhance the connection density and signal integrity between chips. RDL provides electrical connections through multiple layers of copper lines and polymer materials, while LSI offers efficient data transmission paths.
Power and Thermal Management: Advanced packaging design ensures effective power management and thermal solutions, maintaining system stability and reliability during high-performance operations.
High-Bandwidth Memory (HBM)
The application of HBM technology is a major highlight of CoWoS technology. High Bandwidth Memory (HBM) is an advanced memory technology that offers higher data transfer rates and lower power consumption. HBM is typically integrated with processors (such as CPUs or GPUs) and interconnected through a silicon interposer.
Vertical Stacking: HBM employs vertical stacking, where multiple DRAM chips are stacked vertically and connected through Through-Silicon Vias (TSVs), significantly reducing the physical distance between memory and processors.
Wide Bus Design: HBM has a wider data bus compared to traditional DRAM. Each HBM stack has a 1024-bit wide data bus, enabling higher bandwidth data transmission. Traditional DRAM typically has a 64-bit data bus, meaning each data transfer is 64 bits wide. Thus, HBM’s data transfer rate is up to 8 times higher than traditional DRAM.
Low Power Consumption: Vertical stacking shortens the transmission path, reducing energy loss during data transfer. Efficient electrical connections lower current demand in the circuits, and the wide bus design allows HBM to perform more efficient parallel data processing. Therefore, HBM provides high bandwidth while significantly reducing power consumption, which is crucial for high-performance computing and AI applications.
Through-Silicon Via (TSV) Technology
The Through-Silicon Via (TSV) technology involves the vertical processing of tiny holes on a silicon wafer, which are filled with conductive materials (typically copper) to form electrical connections. These vias can penetrate the entire thickness of the silicon wafer, allowing different layers of circuits to connect vertically, rather than relying solely on traditional horizontal connections. TSV technology is a critical component of CoWoS (Chip-on-Wafer-on-Substrate) technology. As a vertical connection technique, TSV enables high-density vertical connections on silicon wafers. By using TSV technology, CoWoS can achieve high-density, high-efficiency inter-chip connections, thereby improving system performance.
Thermal Management and Heat Dissipation
As chip integration increases, thermal management becomes a significant challenge for CoWoS technology. To effectively dissipate heat, CoWoS employs advanced thermal management solutions, such as high-efficiency thermal materials (e.g., copper, graphene) and thermal interface materials (TIM) design, ensuring the system maintains stable temperatures during high-performance operation.
Packaging Design and Manufacturing Process
The success of CoWoS technology relies on advanced packaging design and manufacturing processes. This includes precise chip alignment techniques, high-precision packaging material selection, and advanced manufacturing processes to ensure high-quality and reliable packaging at every step.
Advantages of CoWoS Technology
Improved Performance
CoWoS technology integrates multiple chips on the same substrate, significantly enhancing system performance. This integration shortens data transmission distances, increases transfer rates, reduces latency, and boosts overall computing power.
Reduced Power Consumption
Traditional multi-chip systems suffer from data loss due to long connection distances. CoWoS technology shortens the distance between chips, reducing energy loss during data transmission and thus lowering overall system power consumption.
Increased Reliability
CoWoS technology employs advanced packaging design and manufacturing processes, enhancing system reliability. These techniques ensure stable connections between chips, reducing the risk of failures due to poor connections.
Flexibility and Scalability
CoWoS technology offers high flexibility and scalability. It can integrate various types of chips according to different application needs, accommodating diverse application scenarios.
Application Areas of CoWoS Technology
High-Performance Computing (HPC)
In the field of high-performance computing, enhancing computational power is essential for scientific research and engineering calculations. CoWoS technology integrates multiple processors and high-bandwidth memory, significantly boosting computational capabilities to meet the demands of scientific research, engineering simulations, and data analysis.
Artificial Intelligence (AI)
AI applications require extensive data processing and analysis capabilities. CoWoS technology provides the necessary high-performance computing platform, supporting the training and inference of deep learning and machine learning models. By improving data transfer rates and reducing latency, CoWoS technology accelerates AI algorithms and enhances the efficiency and performance of AI systems.
Big Data Analysis
In big data analysis, the rapid processing and real-time analysis of data are crucial. CoWoS technology improves data transfer rates and computational efficiency, significantly enhancing the performance of big data analysis. This helps enterprises and research institutions quickly extract valuable information from large datasets.
5G and Communication Networks
With the proliferation of 5G technology, the demand for high-performance network equipment is increasing. CoWoS technology improves data transfer rates and signal processing capabilities in communication networks, meeting the high-bandwidth, low-latency requirements of 5G networks.
Automotive Electronics
Smart cars and autonomous driving technologies require robust computational power to process large amounts of sensor data and make real-time decisions. CoWoS technology provides the necessary high-performance computing platform, supporting rapid computation and real-time response in autonomous driving systems, thereby enhancing the safety and reliability of smart vehicles.
Market Forecast and Industry Impact
According to several authoritative institutions, CoWoS technology is expected to significantly drive growth in the semiconductor industry over the next few years.
Gartner： Gartner predicts global semiconductor revenue will grow by 16.8% in 2024, reaching $624 billion, driven mainly by AI workloads, particularly in data centers requiring high-performance GPUs and accelerators.
IDC： IDC reports that the demand for high-performance computing and AI technologies will sustain semiconductor market growth, particularly in high-bandwidth memory and SoC integration.
TechInsights： TechInsights forecasts that 2024 will be a record year for the semiconductor industry, with total revenue exceeding the 2022 peak and doubling to over $1 trillion within the next decade.
AnandTech： AnandTech reports that TSMC plans to expand its CoWoS capacity by 60% annually through 2026 to meet the growing demand for AI and high-performance computing applications.
TSMC Press Releases： TSMC and Broadcom have introduced the world’s first 2X photomask size interposer, significantly boosting computational capabilities for high-performance computing systems, which is expected to substantially increase the company's revenue.
AnySilicon： AnySilicon provides a detailed introduction to CoWoS technology and application cases, emphasizing its advantages in high-performance computing, AI, and big data analysis.
TrendForce： TrendForce's report deeply analyzes advanced packaging technologies, including CoWoS, and explores their applications in AI, data centers, and 5G.
DiskMFR： DiskMFR introduces CoWoS packaging technology applications in high-performance computing, communication networks, image processing, and automotive electronics, highlighting how this technology improves computational performance by integrating multiple processor chips and high-speed caches.
TSMC Official Website： TSMC’s CoWoS platform offers the best performance and highest integration density, particularly suited for high-performance computing applications. The official website details various CoWoS technologies (e.g., CoWoS-S, CoWoS-R, and CoWoS-L) and their applications.
CakeResume： CakeResume provides a comprehensive guide to CoWoS technology applications in high-performance computing, AI and machine learning, 5G networks, and automotive electronics, discussing challenges in thermal management, signal integrity, testing, and quality assurance.
IEEE Xplore： IEEE Xplore offers numerous research papers on CoWoS technology, delving into its technical principles, application scenarios, and future development directions.
Nature Electronics： Nature Electronics publishes multiple papers on advanced packaging technologies, including detailed analysis and research on CoWoS technology.
ScienceDirect： ScienceDirect features many articles detailing the technical principles, application cases, and market prospects of CoWoS technology.
Nature Communications： Nature Communications publishes several papers on advanced semiconductor technologies, including in-depth research on CoWoS technology.
IEEE Transactions on Components, Packaging and Manufacturing Technology： This journal publishes numerous research papers on CoWoS technology, thoroughly analyzing its technical details and application scenarios.
Challenges and Future Development of CoWoS Technology
Despite the enormous potential of CoWoS technology in enhancing computing performance and efficiency, it faces several challenges.
Thermal Management:
With increased chip integration, thermal management becomes crucial. Effective heat dissipation is necessary to prevent overheating and maintain system performance and reliability. Researchers and engineers are developing advanced thermal management techniques, such as high-efficiency thermal materials, active cooling technologies, and innovative heat dissipation structures, to ensure stable temperatures during high-performance operation.
Signal Integrity:
Maintaining signal integrity and stability in high-density packaging is challenging. Signal interference and delay can affect system performance. Solutions include optimizing TSV design, signal path optimization, and using advanced materials and techniques to reduce signal loss and interference.
Testing and Quality Assurance:
High-density packaging requires more complex testing and quality assurance to ensure product reliability and performance. As the number of chips increases, so does the need for comprehensive and precise testing. The industry is developing automated testing technologies and advanced equipment to improve testing efficiency and accuracy.
Future Development Directions
As technology continues to advance, the challenges faced by CoWoS technology are expected to be gradually overcome, allowing it to showcase its advantages in more areas. Here are some potential development directions:
Higher-Density Integration
With manufacturing process advancements, CoWoS technology will achieve higher-density chip integration, further enhancing system computing power and efficiency to meet the demands of higher-performance and more complex applications.
Application of Advanced Materials
The use of advanced materials will improve CoWoS technology's performance and reliability. For example, high-thermal-conductivity materials can enhance thermal management efficiency, and new semiconductor materials can improve chip performance and power consumption.
Intelligent Manufacturing Technologies
The application of intelligent manufacturing technologies will boost CoWoS technology's production efficiency and quality. By incorporating machine learning and artificial intelligence, the production process can be automated and optimized, increasing both efficiency and product quality.
Expansion of New Application Scenarios
As technology matures, CoWoS technology will find new application scenarios, such as in medical electronics, the Internet of Things (IoT), and smart home devices. CoWoS technology will show significant potential in these areas, driving technological progress and industry development.
CoWoS technology, as an advanced packaging technology, enhances computing performance and efficiency, demonstrating broad application prospects in high-performance computing, AI, big data analysis, 5G communications, and automotive electronics. As the technology matures and market demand increases, CoWoS technology is expected to significantly drive the semiconductor industry's growth in the coming years, becoming a key technology for high-performance computing.