Kevin Zhang, Senior Vice President of Business Development at TSMC, introduced the company’s latest technologies at the International Solid-State Circuits Conference (ISSCC) 2024. According to TechNews citing from the speech, Zhang shared insights into future technological advancements, prospects for advanced processes, and the latest semiconductor technologies needed in various fields.

Zhang noted that since the introduction of ChatGPT and Wi-Fi 7, a lot of advanced semiconductor are required, as we are entering an accelerated growth period for semiconductor going forward.

In the automotive sector, the industry is undergoing a revolution, with many suggesting that new vehicles will be software-defined. However, Zhang believes it’s more about silicon-defined because software needs to run on silicon, driving the future of autonomous driving capabilities.

CFET (Complementary Field-Effect Transistor)

In terms of technology, Transistor remain at the heart of the innovation, silicon innovation. It has shifted from geometry reduction to architectural innovation and the use of new materials. Moving from 16-nanometer FinFET to today’s 2-nanometer Nano Sheet technology represents significant progress in high-performance computing and architectural innovation.

What’s next? The answer is CFET.

Kevin Zhang explained that CFET involves stacking nMOS and pMOS on top of each other, significantly improving component currents and increasing transistor density by 1.5 to 2 times.

Alternatively, efforts are being made to create higher-performance switching devices from low-dimensional materials such as 2D materials, surpassing today’s devices or transistors.

Kevin Zhang also showcased that TSMC has successfully fabricated CFET architectures in the laboratory, stating, “This is a real integrated device that has been fabricated in our lab. Here, you see the transistor IV curve. They are beautiful curves. So, this is a significant milestone in terms of continuing to drive the innovation of the transistor architecture.”

However, as the geometry of the transistor shrinks, it becomes increasingly difficult and costly. This necessitates collaboration between process development teams and design research to achieve optimal benefits, known as “Design-Technology Co-Optimization” (DTCO).

In addition, TSMC has introduced FINFLEX technology, enabling chip designers to choose and mix the best fin structures to support each critical functional block, achieving optimal performance, density, and power consumption.

Another example of DTCO is Static Random Access Memory (SRAM). SRAM has scaled from 130 nanometers to the current 3 nanometers, and TSMC has achieved a over 100x density improvement, a result of collaboration or combination of a process innovation and adoption of the more advanced design technique.

Nevertheless, the essence or the objective of this technology scaling is for “energy efficient compute,” as Kevin Zhang expressed. He stated that in the entire semiconductor industry, TSMC has come a long way, and this progress has made today’s AI possible.

• Advancements in HPC/AI Technology Platforms: 3D Stacking, Silicon Photonics, CPO

Whether it’s GPUs, TPUs, or customized ASICs, they all feature this particular integration scheme. Currently, the mainstream is 2.5D packaging. However, to meet future high-performance computing demands, this platform needs significant enhancement, requiring higher density and lower power consumption computation.

Therefore, stacking is needed, including integrating many memory bandwidths and HBM into the package, while considering issues such as power supply, I/O, and interconnect density.

Consequently, Kevin Zhang stated that bringing “silicon photonics into packaging” is the future direction. However, this will face many challenges, such as Co-Packaged Optics (CPO) closer to the electronic side.

1. 3D Stacking

When it comes to 3D stacking, Kevin Zhang presented a diagram and explained that to achieve higher interconnect density, specifically Chip-to-Chip connections, 3D stacking allows the bonding pitch to scale to just a few micrometers, achieving interconnect density like monolithic. “That’s why the 3D (stacking) is the future,” he concluded.

2. Silicon Photonics / Co-Packaged Optics (CPO)

Kevin Zhang pointed out that while electronics excel at computation, photons are better for signaling or communication. He illustrated that if a 50 terabyte switch, an all-electronic copper system were used, it would consume 2,400 W.

The current solution involves using pluggable modules, which can save 40% of power (> 1500W). However, as the need for higher-speed signals and larger bandwidths increases in the future, this solution falls short. Therefore, integrating silicon photonics technology is necessary to introduce photon capabilities.

• Automotive Technology

1. Pursuing Low DPPM

Fundamentally, the latest automotive technologies require significant computational power, but power consumption is becoming a concern, especially for battery-powered vehicles.

Kevin Zhang states that automotive semiconductor technology has lagged behind consumer or HPC technologies by several generations due to stringent safety requirements. The DPPM (Defects Per Million) for automotive applications must be close to zero.

Therefore, fabs, semiconductor manufacturers, and automotive designers must collaborate more closely to accelerate this pace. He also promises, “you will see 3 nanometer in your car before long.”

2. MRAM/RRAM

As automotive transitions to a domain architecture, MCUs (Microcontroller Units) become increasingly important and require advanced semiconductor technology to provide computational capabilities.

Traditional MCUs mostly rely on floating-gate technology, but this technology encounters bottlenecks below 28 nanometers. Fortunately, the industry has invested in new memory technologies, including new non-volatile memories such as Magnetic Random Access Memory (MRAM) or Resistive Random Access Memory (RRAM).

Therefore, transitioning from MCU to MRAM or RRAM-based technologies helps drive continuous technology scaling from 28 nanometers to 16 nanometers, or even 7 nanometers.

• Sensor and Display: CIS (CMOS Image Sensors)

Sensor technology has evolved from simple 2D designs and single layer design to intelligent systems with 3D wafer stacking, essentially layering the signal processing on top of the sensing layer.

Kevin Zhang also mentioned, “our technologies already start investing, researching on the multi-layer design.”

Engaging in three or more layer designs allows for the optimization of pixels, continuing the trend of scaling pixel sizes while meeting resolution requirements and achieving optimal sensing capabilities simultaneously.

Another example is AR (Augmented Reality) and VR (Virtual Reality), where separating memory layers and stacking them onto other logic chips can effectively reduce size while maintaining high-performance demands.

Read more

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(Photo credit: TSMC)

As semiconductor fabrication technologies continue to advance, the number of transistors in integrated circuits (ICs) has steadily increased. Initially, ICs contained only tens of transistors, but as technology progressed, ICs integrating hundreds of thousands of transistors enabled the realization of 3D animation. ICs with millions of transistors allowed computers to enter households, and today, ICs with hundreds of billions or even trillions of transistors enable digital technology to connect the entire world, profoundly impacting people’s lives.

Over the past 65 years, semiconductor fabrication processes have rapidly evolved, driven by Moore’s Law, gradually reshaping society. However, in recent years, semiconductor processes have approached physical limits, and the failure of Moore’s Law has been a topic of concern. In response, 3D IC stacking and heterogeneous integration technologies have emerged as promising solutions.

3D Stacking Trends

With the rapid development of applications such as AI, AR/VR, and 8K, a significant demand for computation is expected to continue, particularly driving parallel computing systems capable of handling vast amounts of data in a short time. As semiconductor processes slow down, 3D packaging has become an effective means to extend Moore’s Law and enhance IC computing performance.

3D packaging technology offers numerous advantages over traditional 2D packaging. It enables size reduction, with silicon interposer efficiency exceeding 100%, improved connectivity, reduced parasitic effects, lower power consumption, lower latency, and higher operating frequencies. These advantages, along with various benefits of 3D integration and interconnection technologies, make 3D packaging a development direction pursued by major players in the industry.

imec’s Vision for 3D Technology

In the field of 3D stacking technology, imec (imec, the Belgian Interuniversity Microelectronics Centre) defines four categories of 3D integration solutions: 3D-SIP, 3D-SIC, 3D-SOC, and 3D-IC, each requiring different process solutions and 3D integration techniques. Eric Beyne, VP R&D, Director 3D System Integration Program at imec specifically notes that concerning 3D interconnection technology, the scope of 3D interconnection will extend from stack packaging below 1 millimeter (mm), such as Package-on-Package (POP), to below 100 nanometers (nm) with true 3D ICs using transistor stacking, surpassing an interconnect density of 108/mm².

imec identifies three key elements in 3D integration technology: Through-Silicon Via (TSV), die-to-die and die-to-wafer stacking and interconnection, and wafer-to-wafer bonding technology. Beyne points out that TSV miniaturization technology continues to evolve. However, regarding “interconnect gaps,” as TSVs further shrink, microbump technology may struggle to meet higher interconnection demands, making cu-cu hybrid bonding technology a focus of development.

▲The image shows imec’s 3D interconnect technology roadmap, illustrating that as packaging technology continues to advance, node sizes shrink, and density further increases in 3D packaging. (Source：ISSCC 2021)

3D-SIP

System-in-Package (SIP), a form of system-level packaging, connects multiple chips that undergo different fabrication processes and preliminary packaging using heterogeneous integration techniques, integrating them within the same packaging shell. 3D-SIP involves vertically stacking multiple SIP chips, including packaging interconnects, fan-out wafer-level packaging, and solder ball bonding.

▲The image on the left is a schematic diagram of 3D-SIP packaging, where the connection points on both sides of the PCB board link the chips that have undergone initial packaging from top to bottom. The image on the right is an actual product illustration. (Source：TrendTorce (Left)，ISSCC 2021(Right))

Currently, the connection pitch in existing solutions is approximately 400 micrometers (µm). imec’s research aims to increase the interconnectivity of such SIPs by 100 times, reducing connection pitch to 40 µm. Common applications of 3D-SIP packaging include RF FEMs, TWS Barbuds SoCs.

3D-SIC

The second category, 3D-SIC (Stacking IC), involves the stacking of individual chips on top of each other. 3D-SIC is achieved by stacking chips on an interposer or wafer, with the finished chips bonded to the top of the wafer. Chips are interconnected through TSVs and microbumps, with industry solutions achieving pitch sizes as small as 40 µm. The technology is applied to products like 3D-DRAM and logic chips, connected alongside optical I/O units on the interposer. Currently, 3D-SIC technology is widely used in High-Bandwidth Memory (HBM) manufacturing.

▲The image depicts a schematic diagram of 3D-SIC, which utilizes cu-cu hybrid bonding technology to connect the upper and lower layers of ICs. (Source:imec)

3D stacking packaging is leading the global semiconductor industry, and imec has outlined a development blueprint focused on reducing interconnection pitch and increasing contact density per unit area, positioning 3D stacking as a solution to continue Moore’s Law amid slowing semiconductor processes.

Explore More

• An In-Depth Explanation of Advanced Packaging Technology: CoWoS
• Intel and Samsung Join TSMC in Fierce Advanced Packaging Race
• Continuing Moore’s Law: Advanced Packaging Enters the 3D Stacked CPU/GPU Era
• Understanding Chiplets, SoC, and SiP: Why TSMC, Intel, Samsung Invest?

This article is from TechNews, a collaborative media partner of TrendForce.

(Photo credit: TSMC )