Shulou(Shulou.com)11/24 Report--

It was reported on August 18 that today, the 2022 World Semiconductor Conference and Nanjing International Semiconductor Expo opened in Nanjing. Mao Junfa, academician of Chinese Academy of Sciences and president of Shenzhen University, delivered a keynote speech at the opening ceremony and high-end forum.

After briefly reviewing the definition of integrated circuit, brief history of development and the reasons for China's backwardness, Academician Mao Junfa focused on sharing the development trend and challenges of integrated system, as well as four key scientific and technological issues that should be focused on.

Academician Mao Junfa believes that "the past 60 years are the era of integrated circuits, and the next 60 years are the era of integrated systems." "He mentioned that as Moore's Law faces extreme challenges and the turning point approaches, semiconductor technology will move from circuit integration to a new path of system integration, which provides a historical opportunity for the development of lane change overtaking in China.

Integrated circuit (IC) is the transistor, resistor, capacitor and inductor and other components and interconnection lines made (integrated) on a small semiconductor wafer or dielectric substrate, forming a circuit with expected functions.

All components are integrated in structure, which makes the circuit develop towards high density, large scale, miniaturization, low power consumption, low cost and high reliability.

Integrated circuits are a reflection of a country's comprehensive scientific and technological strength and even its comprehensive national strength. They are key high-tech tracks that are "stuck" and "cannot be bought with money." China spends huge sums of money every year to import integrated circuits, and high-end chips basically rely on imports.

Looking back on the reasons for the backwardness of integrated circuits in our country, there are not only advanced technologies blocked by the West, but also a period of development before, and the separation of production, learning and research.

Specific to the subdivision field, the main reason for the backwardness of EDA is that there are many R & D algorithms, but they are scattered and there is no planning and integration; the engineering ability of large-scale software is weak, the experience is less, and the users are unwilling to use domestic software tools, a vicious circle.

The backwardness of semiconductor equipment is mainly affected by many factors such as overall capability and market environment. The reasons for the backwardness of devices and circuits include backward materials, insufficient precision and stability of technology, lack of craftsman spirit and master craftsmen.

At this stage, China's integrated circuits urgently need a large number of high-end talents.

II."The next 60 years is the era of integrated systems." The current development direction of integrated circuit industry includes continuation of Moore's Law and detour of Moore's Law. The former faces challenges such as physical principle limit, technical means limit and economic cost limit, while the mainstream trend of the latter includes chiplet, heterogeneity, integrated system, etc.

Academician Mao Junfa judged that the past 60 years were the era of integrated circuits (IC), and the next 60 years were the era of integrated systems (IS).

Integrated circuits (chips) are only the means, he says, and microelectronic systems are the end. The integrated system is designed and manufactured integrally from the system point of view. All kinds of chips, sensors, components, antennas, interconnects, etc. are integrated on a substrate to form a system with expected functions. All chips and components form a whole in structure, which makes the system high density, miniaturization, strong function, low power consumption, low cost, high reliability, easy design and easy manufacture.

This idea can further improve the design efficiency and overall performance of the system, reduce the cost of the system, increase its reliability, and reduce the requirements for chip design and equipment.

There are three meanings to realize the leap from integrated circuit to integrated system, which is a new way for the development of complex microsystem integration technology, a new direction for the development of integrated circuit in the post-Moore era, and a new opportunity for the development of semiconductor technology to change lanes and overtake.

Chiplet technology is a special integrated system concept, which decomposes a large chip with a single advanced process into multiple feature modules, each module (chiplet) is realized with its own most suitable process. Chiplet technology and SoC reverse thinking: SoC integrates semiconductor IP planes into a chip, SoIC integrates multiple chiplets in 3D stacks.

At present, the integration of front-end design and processing and back-end packaging of integrated circuits gradually converges. The focus of package integration technology is slowly shifting from traditional back-end packaging to front-end semiconductor foundry.

SoIC of TSMC's 3D Fabric platform, a leading foundry company in China Taiwan, adopts the most advanced package interconnection technology Hybrid Bonding, and the interconnection pitch between stacked chips can be as small as submicron. At present, TSMC has realized the completion of 12-layer stacked SoIC with 3D fabric.

If TSMC's 3D fabric, especially SoIC, becomes the mainstream technology of the next generation chip system, TSMC will be stronger in the semiconductor industry, while the mainland of China's situation of weak foundry and strong packaging will become backward in foundry and packaging.

Another example of an integrated system is Antenna in Package (AiP) technology. AiP refers to the antenna implemented in the package structure containing wireless chips. Compared with ordinary discrete antennas, AIP has better system performance, smaller PCB area, lower cost, and shorter R & D cycle.

A third example is multifunctional passive component technology. Electronic systems contain a large number of passive components, different functional components, antenna cascade needs a lot of switching, introducing additional loss and volume; a variety of components combined into a coordinated design of multifunctional components, can significantly reduce the number of components and switching required by the system, reduce insertion loss, achieve miniaturization.

Semiconductor heterogeneous integration technology is the most powerful technical means of integrated systems, which can break through the functional and performance limits of a single process and achieve stronger complex performance and excellent comprehensive performance.

It integrates compound semiconductor high-performance devices or chips of different process nodes, silicon-based low-cost high-integration devices or chips, and passive elements or antennas through heterogeneous bonding or epitaxial growth to realize integrated circuit or system technology.

According to Academician Mao Junfa, the integrated system is facing four key scientific and technological problems.

The first is the integrated system architecture, including defining the functions and performance of the integrated system, and decomposing the structure; determining the types of chips and various components, and selecting the integration process; and the layout, interconnection mode and standard of the integrated system.

The second is automatic intelligent collaborative design, including electromagnetic-thermal-stress multi-physical collaborative design, active/passive circuit/antenna and digital, analog, RF circuit multifunctional collaborative design, but also IP, IPD, PDK, chiplet and other multiplexing.

The third is heterogeneous interface formation and quantitative control mechanism of technology. The adjustment of process parameters of integrated system is subject to the characteristics of electric, thermal and stress fields. Because of the difference of lattice and expansion coefficient, it is necessary to establish heterogeneous interface dynamics, understand diffusion, nucleation and adhesion mechanism, and realize high reliable heterogeneous integration through interface regulation and fusion.

Fourth, miniaturization of passive components and antennas is crucial to the entire RF integrated system. Passive components can account for up to 90% of the total number of RF electronic system components, 80% of the total area of the system, area, process and chip differences. Due to RF loss, EMC and thermal problems, miniaturization and performance improvement are challenged. It is necessary to break through the traditional thinking and propose new working mechanism and design theory.

Conclusion: Academician Mao Junfa shared that at present, the integration degree and working speed of integrated systems are constantly improving, and at the same time, they are facing three main challenges: multi-physical regulation, multi-performance collaboration and multi-material fusion.

Integrated system technology is regarded as an important development direction in policy and industry both at home and abroad. The United States launched the Microelectronics Program and the Electronic Renaissance Program at the United University in 2018, both of which focus on heterogeneous integration. Shanghai Jiaotong University, China Power Group, Chinese Academy of Sciences, Changdian Science and Technology and other industry-university-research institutions are also carrying out system packaging research. In addition, Japan, South Korea, Singapore and other places have heterogeneous integration related research plans. TSMC, Intel, IBM, Samsung and other domestic and foreign semiconductor manufacturers are doing 3D package integration research.

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