Tsinghua University developed a meta-imaging chip: getting rid of EUV lithography machine, there is a new way

A few days ago, good news came from the domestic chip field: Tsinghua University broke through the problem of optical aberration and successfully developed a meta-imaging chip. There may be a new breakthrough in the field of chip design and manufacturing.

According to the website of the Chinese Academy of Sciences, a research team from the Imaging and Intelligent Technology Laboratory of Tsinghua University proposed an integrated meta-imaging chip architecture and developed a meta-imaging chip. The team developed a super sensor that records the imaging process and Not the image itself, by realizing ultra-fine perception and fusion of incoherent complex light fields, even though imperfect optical lenses can still achieve perfect 3D optical imaging.

It is said that reducing optical aberrations is a century-old optical problem. The transmission of light through each surface of the optical system will form a variety of aberrations, resulting in defects such as blurring and deformation of the image. An important task of optical system design is to correct these aberrations, so that the imaging quality can meet the technical requirements and achieve perfect imaging.

In the past, many optical scientists and engineers have been trying to make breakthroughs, but due to the limitations of processing technology and the interference of complex environments, it is difficult to create a perfect imaging system.

It is reported that in this research result, the research team integrated all technologies on a single imaging chip, making it widely applicable to almost all imaging scenarios without additional modification of the existing imaging system, and established the wave optics category The digital adaptive optics architecture based on the advanced technology, through the high-dimensional and ultra-fine perception and fusion of complex light fields, has great flexibility while maintaining unprecedented imaging accuracy.

According to Dai Qionghai, an academician of the Chinese Academy of Engineering and a professor of the Department of Automation of Tsinghua University, this advantage enables the manipulation of complex light fields on the digital side to be comparable to the analog modulation of the physical world, just as people can really move every light in the digital world. The process of perception and correction is completely decoupled, so that high-performance aberration correction in different areas can be achieved simultaneously.

Professor Dai Qionghai also said that the meta-imaging architecture, the establishment of a new generation of general-purpose image sensor architecture, may be widely used in astronomical observation, industrial testing, mobile terminals, security monitoring, medical diagnosis and other fields.

It can be seen from this that the digital adaptive optics capabilities of metachips are expected to bring about changes in imaging systems. The meta-imaging chip is expected to become a general-purpose chip and be applied to various fields such as industry, mobile terminals, and medical care.

This means that in the field of mobile terminal products such as smartphones, it is also expected to usher in another chip alternative.

To get rid of the dependence of EUV lithography machine, both at home and abroad are exploring

In the field of chips, we have talked about domestic substitution the most in recent years, but the difficulty of domestic substitution lies in the dependence of EUV lithography machines. As long as the chip manufacturing process goes into 7nm, the Epistar instruments used in the production of chips must use the EUV lithography machine of ASML in the Netherlands, because the EUV lithography machine has the highest process accuracy at present, which can effectively improve the high-end chip products in the production process. Yield, only EUV lithography machine can process it on a large scale to increase output efficiency.

However, due to the backward foundation in this regard, China lacks advanced technology to develop advanced wafer production, and it is difficult to master EUV lithography technology.

Not only China, but even from a global perspective, the advanced chip manufacturing process cannot get rid of the dependence of the Dutch ASML lithography machine. ASML constitutes an absolute monopoly on the whole world. Whether it is China or other countries, if it focuses on its original route To develop it, it will cost a lot of money and take a long time.

From the current point of view, many manufacturers are trying to find another way to replace EUV lithography technology to produce more advanced processes. For example, Japan’s NIL mass production technology, Intel’s new 3D stacking, multi-chip packaging technology, and Russia’s X-ray lithography machine technology.

From a domestic point of view, two paths have been formed, one is Chiplet technology. One is the photonic chip.

Under the traditional SoC route, the processor, memory, signal, and circuit modules are all integrated into one chip. Chiplet technology combines the module chip and the underlying basic chip through die-to-die through advanced packaging technology, like building blocks. In the same way, many small chips (Chiplets) are integrated together to realize the integrated chip system.

The purpose of the chiplet technology is to make the chips manufactured by the 10nm process expected to reach the integration level of the 7nm chips through the new connection form.

Advanced processes are approaching physical limits, and Chiplet may be an important means to continue Moore’s Law. From the perspective of the reality of the current technical path, Chiplet technology may be very suitable for a domestic technical route to realize overtaking on a curve under the background of chip stuck neck.

In addition, photonic chips. Electronic chips use electrons to generate, process and transmit information, while photonic chips use photons to generate, process, transmit and display information.

Photonic chips are very different from traditional electronic chips in terms of materials and manufacturing processes. Unlike electronic chips, which focus on lithography, and photonic chips, which focus on epitaxy design and preparation, not lithography, in the photonic chip industry, the IDM model is the mainstream.

Photonic chips are similar to a revolution in optical materials. The raw materials and technical paths for manufacturing have changed. Its structure is simple. Photonic chips can be produced using relatively mature raw materials and equipment in my country, and no longer rely on EUV high-end lithography machines.

At present, the first “multi-material, cross-scale” photonic chip production line in China is under preparation. As a new chip development route that breaks through traditional lithography machine technology, photonic chips are also worth looking forward to.

The imagination space of meta-imaging chips

From the current point of view, it is also worth looking forward to whether the meta-imaging chip can become a new way to get rid of the imaging mode of traditional lithography machines.

From the perspective of the principle of the current meta-imaging chip, it is different from the mode of creating traditional electronic chips by lithography machines. Its mode is more inclined to optics, which is similar to that of photonic chips, which are based on the foundation of optical technology. superior.

The metamirror chip is a new optical design method – digital adaptive optics. It is not only suitable for mobile terminals, but also for industrial fields, medical fields and many other aspects. This is a bit similar to a dimensional upgrade model in the field of operating systems – directly making an IoT operating system is equivalent to reducing dimensionality and accommodating a mobile Internet operating system.

From the perspective of its optical technology principle, the meta-imaging chip may not be designed and manufactured along the path of the existing lithography machine. In the author’s opinion, as a three-dimensional optical imaging technology, if it enters the industrial application stage in the future, it is expected to It is applied to the field of lithography imaging, and a new path is found. We know that the principle of lithography itself is also related to optical imaging.

When a chip manufacturer uses a lithography machine to produce a chip, it will first imprint the circuit diagram on the wafer, so that the circuit image will be imaged on the wafer . Design drawings are reduced to chips , and these patterns are then inspected with the help of advanced metrology systems and software to improve the accuracy and yield of chip production. This is a two-dimensional imaging technique.

To make an image metaphor, the function of lithography is similar to that of a camera, and the lithography machine is an enlarged “SLR” . The pictures taken by the camera are imprinted on the negative, while the lithography engraves the circuit diagrams and other electronic components, which are imaged on the wafer.

Today, the meta-imaging architecture itself is the ultra-fine dimensional perception and fusion of complex squares from the bottom sensor end, providing a scalable distributed solution, a kind of 3D optical imaging, and a new “chip photography technology” ” ——Integrate all the technologies on a single imaging chip, ignoring the interference in the process of light propagation, it can correct the imaging by “moving the light”, it is a new imaging mode, which allows us to use very simple The optical system achieves high-performance imaging and can be widely used in almost all imaging scenarios.

We know that the lithography machine itself also involves complex optical imaging lenses and optical systems. The three core components of a lithography machine are workbench, optical lens and light source technology. The lens of the lithography machine is made of A complex optical system composed of dozens of independent lenses and mirrors.

The complexity of the lithography machine makes the realization of a high-quality optical system a huge systematic project, which requires the designed integrated circuit pattern on the mask to be printed on the photosensitive material through the exposure of light to form a pattern. This process requires thousands of actuators to fine-tune the precise position and orientation of each lens and mirror assembly to ensure the perfect pattern on the wafer every time.

However, the limitations and shortcomings of traditional lithography machines also exist, that is, the use of highly repetitive, high-energy light pulses will heat up the optical system, resulting in lens distortion. Small changes can still make defective chips. Actuators in optical assemblies are used to actively compensate for the thermal effects of these lenses.

The ability of a lithography machine to clearly project the smallest image is one of the most important technical indicators of a lithography machine.

From the perspective of the principle of the meta-imaging chip, we can vaguely see a new way of chip design and manufacturing. The meta-imaging core records the imaging process rather than the image itself. By realizing ultra-fine perception and fusion of incoherent complex light fields, Even through imperfect optical lenses and complex imaging environments, perfect 3D optical imaging can still be achieved. This is a breakthrough in chip imaging technology.

However, from the current point of view, the technology is still far from industrialization, and the future application of this technology is still uncertain, but whether it can be applied to the imaging system and principle of the lithography machine, changing the original lithography There are still doubts about the imaging mode of the camera, but it is still worth looking forward to.

Domestic substitution in the chip field is a road that must be taken in China at present, and it is also a very difficult road to seek autonomy in underlying technology.

At present, we are very pleased to see that the exploration of various technologies in China continues to advance, and the self-controllable crisis awareness and scientific research atmosphere are significantly better than in the past, which is undoubtedly quite inspiring.

From Chiplet technology to photonic chips to meta-imaging chips, which technology model will take the lead in making breakthroughs? In the next three to five years, there may be an answer, we will wait and see.

Author: Wang Xinxi, senior commentator of TMT, this article is not allowed to be reproduced without permission