Over the past few decades, semiconductor manufacturing technology has evolved from the 10,000nm process in 1971 to the 3nm process in 2022, driven by the need to increase the number of transistors on chips for enhanced computational performance. However, as applications like artificial intelligence (AI) and AIGC rapidly advance, demand for higher core chip performance at the device level is growing.

While process technology improvements may encounter bottlenecks, the need for computing resources continues to rise. This underscores the importance of advanced packaging techniques to boost the number of transistors on chips.

In recent years, “advanced packaging” has gained significant attention. Think of “packaging” as a protective shell for electronic chips, safeguarding them from adverse environmental effects. Chip packaging involves fixation, enhanced heat dissipation, electrical connections, and signal interconnections with the outside world. The term “advanced packaging” primarily focuses on packaging techniques for chips with process nodes below 7nm.

Amid the AI boom, which has driven demand for AI servers and NVIDIA GPU graphics chips, CoWoS (Chip-on-Wafer-on-Substrate) packaging has faced a supply shortage.

But what exactly is CoWoS?

CoWoS is a 2.5D and 3D packaging technology, composed of “CoW” (Chip-on-Wafer) and “WoS” (Wafer-on-Substrate). CoWoS involves stacking chips and then packaging them onto a substrate, creating a 2.5D or 3D configuration. This approach reduces chip space, while also lowering power consumption and costs. The concept is illustrated in the diagram below, where logic chips and High-Bandwidth Memory (HBM) are interconnected on an interposer through tiny metal wires. “Through-Silicon Vias (TSV)” technology links the assembly to the substrate beneath, ultimately connecting to external circuits via solder balls.

The difference between 2.5D and 3D packaging lies in their stacking methods. 2.5D packaging involves horizontal chip stacking on an interposer or through silicon bridges, mainly for combining logic and high-bandwidth memory chips. 3D packaging vertically stacks chips, primarily targeting high-performance logic chips and System-on-Chip (SoC) designs.

When discussing advanced packaging, it’s worth noting that Taiwan Semiconductor Manufacturing Company (TSMC), rather than traditional packaging and testing facilities, is at the forefront. CoW, being a precise part of CoWoS, is predominantly produced by TSMC. This situation has paved the way for TSMC’s comprehensive service offerings, which maintain high yields in both fabrication and packaging processes. Such a setup ensures an unparalleled approach to serving high-end clients in the future.

Applications of CoWoS

The shift towards multiple small chips and memory stacking is becoming an inevitable trend for high-end chips. CoWoS packaging finds application in a wide range of fields, including High-Performance Computing (HPC), AI, data centers, 5G, Internet of Things (IoT), automotive electronics, and more. In various major trends, CoWoS packaging is set to play a vital role.

In the past, chip performance was primarily reliant on semiconductor process improvements. However, with devices approaching physical limits and chip miniaturization becoming increasingly challenging, maintaining small form factors and high chip performance has required improvements not only in advanced processes but also in chip architecture. This has led to a transition from single-layer chips to multi-layer stacking. As a result, advanced packaging has become a key driver in extending Moore’s Law and is leading the charge in the semiconductor industry.

(Photo credit: TSMC)

Current U.S. sanctions on China have extended their reach to strike at HPC and sectors such as aerospace, automotive market, and military industry. TrendForce indicates, the market for high-end computing chips (including CPU, GPU, etc.) has borne the brunt of these restrictions at this stage, while those providing related storage such as DRAM and NAND Flash also face potential supply disruption. At present, this not only includes domestic companies in mainland China but also extends to related US-based suppliers. Among them, server companies that rely on high-intensity computing will face greater scrutiny.

Impact analysis on server terminal shipments

In terms of server terminal shipments, since relevant component suppliers have not yet been able to confirm whether services provided by the four major cloud service providers (CSPs) in China, Baidu, ByteDance, Alibaba, and Tencent, involve military use, before CSPs sign MOUs (memoranda of understanding), component manufacturers may temporarily delay shipments to the Chinese market. However, TrendForce believes, due to the fact that current CSP buyers’ component inventories remain sufficient, the short-term impact on global server market shipment performance is relatively low and long-term impact depends on the evolution of the US Department of Commerce’s rules.

Huawei and Sugon, two companies that have received attention at this stage due to the US ban, have previously withdrawn from the x86 server market and turned into cloud business providers and whole server delivery has been transferred to other domestic OEMs and outsourced computing power leasing, so as not to be affected by sanctions. However, due to the previous CPU ban, Sugon has turned to AMD to obtain authorization for localized chips, which may be significantly curtailed by this ban. In 2022, Sugon’s market share in the overall server market will be approximately 2.3% and 8.5% of the Chinese market.

TrendForce believes, it cannot be ruled out that relevant Chinese OEMs may have server products that may be rendered to government supercomputing centers in the future. Inspur, H3C, and Lenovo will face more exacting future scrutiny and, if consequences intensify, the mainland Chinese industrial chain may feel direct effects. Although commercial servers are not currently on the list of directly restricted items, if friction between the United States and China intensifies in the future, it cannot be ruled out that the U.S. Department of Commerce will add more potentially risky Chinese server OEMs and CSPs onto the UVL list. If certification cannot be realized within 60 days of being included in the UVL list, these entities will be included on the entity list. The worst case scenario will be a future trend of negative growth in Chinese server demand.

Since the restrictions enumerated in this ban are primarily concentrated in the HPC field, the greatest factor affecting Sugon is the company largely providing server OEM to government departments including in supercomputers, military aerospace, and government server farms. At present, there are 8 national-level supercomputing centers in mainland China and the supercomputer located in the center of Wuxi is the headquarters of China’s self-developed chips including the self-developed Sunway TaihuLight. As the U.S. Department of Commerce continues to strengthen its sanctions, China’s supercomputing technology and domestic research capabilities will be severely damaged in the future.

Impact analysis on GPU and CPU sectors

At present, companies utilizing high-end graphics cards are primarily concentrated in the HPC sector. In terms of CSPs, Alibaba and Baidu are the largest companies in mainland China. These two CSP companies account for up to 60% of the market share of GPU usage in China. Before the previous ban at the end of August, Chinese CSP operators had to submit purchase applications before procurement but they could not apply at all after the ban. However, based on the premise that buyer inventory levels on hand remain high and the supply of goods through distribution channels is sufficient, no effect on demand is forecast until 1H23. Nonetheless, it will be a challenge in the long-term. Since the ban expressly prohibits supercomputing center applications such as HPC, TrendForce assesses that GPU servers used by supercomputing centers will be directly affected, which accounts for up to 30% of China’s GPU market.

In terms of chip computing performance control, ECCNs 3A090 and 4A090 are newly added sanctioned items and chips with a total processing performance of more than 4,800 (inclusive) calculated by TOPS will be restricted. GPUs are usually used to directly assist in performing complex operations. Basically, NVIDIA’s A100 PCIe Gen4 and AMD’s MI250 OAM Module exceed the 4,800 limit. With new high computing performance products restricted in the future, development of server acceleration computing in China will take a hit.

However, the computing performance of most server CPU products is generally lower than the provisions of the ban. Only Chinese-made chips such as Tianjin Haiguang face direct restrictions and other CPUs such as Intel and AMD servers will not be subject to prohibition. At this stage, Intel and AMD will sign MOUs with relevant mainland Chinese manufacturers to ensure that related products cannot be used in military and supercomputing fields before shipment. In today’s server CPUs, the computing performance of the commonly used Intel Ice Lake CPU series does not reach the limit imposed by U.S. sanctions.

Impact analysis on the memory sector

At present, Samsung and SK hynix have also suspended their supply of product to Sugon. If Sugon can clarify procured memory is not used for supercomputing, domestic server products, etc., the parties will be able to reach a consensus for shipment. In the long run, Korean companies are evaluating whether they need a written commitment from each customer to disavow using purchasing memory products in supercomputers. Therefore, some memory shipments may be affected before documents are signed. The industry generally believes that market inventory remains relatively abundant and there will be no substantial damage to the market in the short term. As far as SSD is concerned, the greatest utilization remains in the category of AI/DL (Deep Learning), since most of the data trained from DL must be stored in faster and more convenient SSDs for use in inference scenarios. If the suspension of shipments caused by the current ban cannot be rectified by relevant buyer agreements, the development of Chinese server manufacturers in related AI/DL fields may be hamstrung and a calamitous decline in the market penetration rate of enterprise SSDs from international manufacturers cannot be ruled out.

Impact analysis on the networking sector

There are three reasons for a relatively minor impact assessment on the well-connected suppliers in the networking sector. First, there are numerous networking suppliers and many of them are in China. Since the demand for key components is relatively small, Chinese suppliers should be able to keep up. Second, the mainstream process in this field is a mature process and future expansion is less restricted. Third, from the perspective of supplier shipments, after foundry assembly, packaging, and testing, there are multiple distribution channels for the circulation of the final product and it will be difficult to determine whether terminals are military use. However, from the perspective of long-term impact, there is a high probability that Chinese manufacturers will give priority to China’s local supply chain in the future to ensure future supply. This move will undoubtedly deepen the resistance of other suppliers’ shipments to China, so it is necessary to open up multiple shipping channels to stabilize market share.

（Image credit: iStock）