Semiconductor advanced packaging technology is becoming a key link to promote the performance of electronic products, as Moore's Law approaches the physical limit, the traditional transistor reduction path is facing challenges, and the industry is turning to the innovation of packaging technology. Advanced packaging not only improves the performance of chips, but also improves system-level efficiency and functionality through heterogeneous integration and multi-chip packaging. However, despite its enormous potential, semiconductor advanced packaging still faces a complex set of challenges that must be overcome to unlock its full value.
First of all, the issue of thermal management is a significant technical bottleneck. As chip integration increases, more functions are integrated in a single package, resulting in a significant increase in power density. Especially in 3D packaging, where multiple chips are stacked on top of each other, the difficulty of heat dissipation increases exponentially. If the accumulation of heat cannot be effectively controlled, the performance of the chip will be affected and even the function will fail. Therefore, how to design efficient heat dissipation paths and develop new materials and processes to improve heat dissipation is a key topic for future advanced packaging.
At the same time, the compatibility of materials also puts the reliability of the package to the test. During the packaging process, silicon chips, metal interconnects, and packaging materials often have different coefficients of thermal expansion, and temperature changes can create mechanical stresses inside the package, which can lead to chip failure or cracks. This means that when it comes to material selection, engineers not only have to consider the thermal conductivity and mechanical strength of the material, but also ensure that the thermal expansion behavior of different materials can be matched to reduce the effects of stress.
The increase in interconnection density is also a challenge. As chip sizes continue to shrink, the electrical interconnects in packages become denser, especially in 2.5D and 3D packages, where vertical interconnects between chips result in shorter signal transmission paths and improved performance. However, dense interconnections also pose problems with signal integrity. High-speed data transmission requires the lowest possible noise and latency in the interconnect, placing new demands on design and manufacturing, requiring a balance between signal integrity and power consumption.
Figure: The development history of advanced packaging (Source: Aidan Taylor)
Cost and complexity are another important factor hindering the widespread adoption of advanced packaging technologies. Compared to traditional packaging processes, the production process of advanced packaging is more complex, involving more steps and more elaborate manufacturing equipment. For example, the application of technologies such as wafer-level packaging, fan-out packaging, and silicon interposers increases the complexity of packaging, which not only increases production costs, but also makes yield control in manufacturing difficult. How to maintain high-quality production while reducing costs is still a core problem that needs to be solved in the industry.
The difficulty of design and verification should not be overlooked. As packaging integration increases, designers need to consider not only the layout and interconnection of a single chip, but also the communication, thermal management, and power distribution between multiple chips. This increases the complexity of the design, especially in heterogeneous integration scenarios, where the package may contain CPUs, GPUs, memory chips, and other ASICs, making it a challenge to ensure that they work together efficiently. In addition, the verification of package designs has become more difficult, and the traditional chip verification process has become difficult to adapt to the complexity of the package, and each subsystem and the overall system within the package need to be thoroughly tested to ensure the reliability and performance of the package in different application scenarios.
Finally, supply chain constraints and insufficient production capacity have also affected the rollout of advanced packaging. Tensions in the global semiconductor supply chain have become a common issue in the industry, and advanced packaging technologies are more demanding on materials and equipment, which further exacerbates the pressure on the supply chain. At the same time, the specialized equipment and processes required for advanced packaging are not widely used by all manufacturers, and only a few top fabs and packaging fabs have these capabilities, which leads to capacity constraints to meet market demand for advanced packaging technology.
Overall, semiconductor advanced packaging technology has brought many performance and functional improvements, but to achieve breakthroughs in a wider range of applications, it still needs to innovate and optimize at multiple levels such as thermal management, materials, interconnect, cost, design, and supply chain. Only by overcoming these challenges can advanced packaging technologies reach their full potential in the semiconductor industry of the future, supporting cutting-edge fields such as artificial intelligence, 5G communications, and autonomous driving.
