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Chapter 627 Is it possible that we cannot build EUV lithography machines without foreign technology?

"Did it get stuck again?"

After reading Lin Nan's report email, Chen Yansen frowned slightly.

He never expected that even though he had already kicked open the door and paved the way for them, these people still couldn't take another step forward.

There are two main difficulties at present:
First, the aspherical mirrors in the relay mirror group need to have a surface shape accuracy of less than 50 picometers and a surface roughness of less than 0.1 nanometers root mean square error.

In other words, this is equivalent to requiring that the overall undulation of an area the size of Huian Province cannot exceed the thickness of an A4 sheet of paper.

The difficulty can be imagined!

Currently, only Sega from the United States and Zeiss from Germany possess the corresponding level of mirror polishing technology.

However, due to the restrictions of the Wassenaar Arrangement, even if they spend money, they cannot obtain a supply quota.

While Harbin Institute of Technology, National University of Defense Technology, and Changchun Institute of Optics, Fine Mechanics and Physics of the Chinese Academy of Sciences possess ion beam polishing and magnetorheological polishing technologies, which theoretically can achieve atomic-level surface precision, there is often a huge gap between reality and theory.

This is like asking whether China can manufacture F1 racing car engines.
Logically speaking, China has no shortage of factories capable of producing metal pistons and cylinders, and it also understands the manufacturing principles of internal combustion engines.

However, an F1 racing engine is not a simple combination of individual components. It is an integration of cutting-edge technologies such as materials science, precision machining, thermodynamics, and electronic control systems, and its parameters for speed, thermal efficiency, and reliability have reached the industry's highest standards.

This shows that even if you understand the technical principles, there is still a significant gap to bridge in applying them to stable actual production.

Understanding something is one thing, creating it is another.

Secondly, after the mirror is polished, 40 to 60 pairs of alternating molybdenum and silicon thin film layers must be deposited on the surface, and the thickness error of each layer must be controlled at the atomic level.

Although many research institutes in China have mastered the magnetron sputtering technology required for the coating process, it still does not meet the requirements of EUV lithography machines in terms of uniformity and precision.

In addition, accurately detecting the smoothness of the mirror surface is also a challenge.

Without measurement, there is no processing!

The level of inspection capability determines the ceiling for polishing quality.

In 2014, China's high-precision interferometers, especially its testing equipment and technology for the EUV band, could not even reach a measurement accuracy of 50 picometers.

Lin Nan and Wang Xiangchao, along with hundreds of other R&D engineers, are already leaders in the optics field. If even they can't handle something, asking others will most likely be futile.

They tried their best, but their abilities were limited.

Chen Yansen knew that if he didn't step in, this major scientific research campaign would most likely become a joke.

After a moment's thought, he asked Lin Nan to send over the technical documents for ion beam polishing, magnetorheological polishing, and magnetron sputtering.

at the same time.

Shanghai, Xingyuan Technology Optical R&D Center.

Lin Nan leaned against the lab table, his eyes bloodshot and his expression gloomy.

Wang Xiangchao sat to the side, patted Lin Nan on the shoulder and said, "Don't worry, there's always a way. Take it slow and see. Now that we have a plan, what's there to be afraid of not being able to handle the process issues?"

An expert from the Shanghai Institute of Optics and Fine Mechanics nodded in agreement, saying, "In the past, we didn't need polishing precision at the picometer level, so the technological progress was slow. Now it's different. As long as we can master the aspherical mirror of the illumination system, we've essentially secured half of the core technology for the optical system of the EUV lithography machine."

That being said, the atmosphere in the laboratory did not ease much.

Lin Nan gave a wry smile and pointed to the test report on the table: "I understand the theory, but the reality is that our instrument's testing accuracy is only at the sub-nanometer level. We have no idea whether the surface accuracy is sufficient."

This is like walking with your eyes closed; you're not even sure if you're heading in the right direction, so how can you improve?

The young engineer at the Yanjing Institute of Optoelectronics choked up and murmured in despair, "Does this mean we can't manufacture the core components of an EUV lithography machine without foreign technical support?"

These words were like a steel needle, piercing everyone's confidence.

"Bullshit! They've spent decades accumulating this technology, and we've only been using it for a few days? Don't you even have that much patience?"

Wang Xiangchao suddenly stood up and retorted loudly, "We figured out the lighting system plan in just one month, which proves that our approach was correct."

I've already communicated with the people at the Changchun and Yanjing Institutes of Optics, Fine Mechanics and Physics. From now on, we'll work together: we'll first tackle the projection lens system, and once the polishing and coating technologies meet the standards, we'll integrate the other technologies. We'll definitely be able to crack this tough nut.

His words were like a shot in the arm, slightly warming up the gloomy atmosphere in the laboratory.

Lin Nan took a deep breath, then stood up and said, "Old Wang is right. Let's focus on the optical path design of the projection lens system according to our division of labor."

The experts from the Shanghai Institute of Optics and Fine Mechanics immediately took out the blueprints and pointed to the complex optical path structure: "The projection lens must accurately focus the beam of light from the illumination system onto the wafer and eliminate various aberrations. This requires even higher curvature accuracy for the lens than for a reflecting mirror."

The optical path we designed previously still exhibited an aberration deviation of 0.5 arcseconds in the simulation environment, requiring further optimization.

Wang Xiangchao leaned closer to the blueprints and added, "I've checked the data. Zeiss's projection lens uses 15 high-precision lenses, and the surface shape error of each lens is controlled within 20 picometers."

"If we can reduce the aberration deviation to below 0.2 arcseconds, and catch up with the subsequent processes, we might be able to catch up with their level." The group became more and more engrossed in their conversation, and immediately began working around the drawings and computers.

Wang Xiangchao was in charge of adjusting the optical path simulation parameters, while Lin Nan led a group of people to calculate the correspondence between lens curvature and aberration. The remaining R&D personnel also quickly suppressed their previous negative emotions and devoted their energy to their respective work.

……

……

The next morning, Chen Yansen called Tao Jingwen and, with the help of Meng Yuanzhi's connections, obtained a pass to Luzhou University of Science and Technology, which allowed him free access to the optoelectronic laboratory.

Both mirror polishing and coating processes need to be continuously improved through experiments in order to find the direction for optimization.

Theoretical calculations alone cannot yield results.

At the same time, Lin Nan also dispatched a group of R&D personnel specializing in ultra-precision polishing technology to Luzhou.

When Liu Fengjun and others entered the optoelectronic laboratory of Luzhou University of Science and Technology, they saw Chen Yansen changing into cleanroom suits, putting on clean latex gloves and cleanroom masks.

Isn't he the founder of Senlian Capital?

Why in the lab?
"Mr. Liu, it's a pleasure to meet you!" Chen Yansen stopped what he was doing, walked straight towards Liu Fengjun, and then extended his right hand to say.

"Hello, Mr. Chen." Although Liu Fengjun had a lot of questions, he didn't want to ask them directly.

He is a senior researcher in the ultra-precision machining team at the National University of Defense Technology, with a doctoral degree and exceptional intelligence.

With such high moral character, he is destined not to say anything that shows a lack of emotional intelligence.

"The lab just finished debugging the ion beam polishing machine. Since you're here, let's take a look at the parameters together."

Chen Yansen withdrew his right hand and pointed to the control screen next to him, where a dense stream of data was jumping around. He then said, "I have seen the mirror-finish blanks you made in Shanghai. The purity of the silicon-based material is sufficient, but the initial surface shape error is still 3 nanometers. They need to be pre-treated by magnetorheological polishing."

Liu Fengjun's pupils contracted slightly, and he was deeply shocked.

He subconsciously walked to the control panel and his gaze fell on the pretreatment parameters of magnetorheological polishing.

To his surprise, the screen not only clearly listed the particle size distribution of the grinding fluid at different rotation speeds and the magnetic field strength gradient curve, but also marked a specific point that "the error after pretreatment must be controlled within 500 picometers".

"Mr. Chen, did you calculate the stress release curve of silicon-based materials in advance?"

Liu Fengjun couldn't help but press for an answer.

It is important to know that silicon-based mirrors will undergo minute deformations due to stress accumulation during the grinding process. This is the most challenging problem in the field of ultra-precision machining and a technical obstacle that major universities and research institutes in China have been unable to overcome for a long time.

Now, the solution has been found here.

He has been immersed in this field for many years, and it is precisely because he understands it that he knows how much ingenuity is hidden behind this set of parameters.

Chen Yansen nodded slightly: "The stress release of silicon-based materials is delayed. A 0.3% compensation amount must be left during pretreatment, otherwise there will be springback error after cooling after polishing. Get to work first, and ask me any questions you may have."

"Xiao Wang, adjust the magnetorheological polishing machine according to these parameters, and first measure the stress distribution of the first rough blank."

Liu Fengjun turned to the researchers behind him and gave instructions, his voice filled with barely concealed urgency.

Chen Yansen didn't say anything more and turned to walk towards another piece of equipment.

For the next few days, Liu Fengjun followed Chen Yansen around like a shadow, acting like a student, assistant, and follower.

The more he learned about Chen Yansen, the more he appreciated his amazing talent in the field of ultra-precision machining.

Once upon a time, Liu Fengjun was also a top scorer in the college entrance examination and was admitted to the special class for gifted children at the National University of Defense Technology. He was a scientific research genius among his peers, but in front of Chen Yansen, he was like an ant looking at the blue sky.

Chen Yansen only spends two hours a day at Luzhou University of Science and Technology, with most of the work being done by Liu Fengjun and others.

They first developed sub-aperture stitching technology, then introduced computational holography, and by equipping it with an atomic force microscope and an optical scattering instrument, they were the first to improve the detection accuracy to the picometer level.

Upon hearing the news, everyone at the Shanghai Optics Department's R&D center was instantly invigorated.

After all, with testing tools, there is a clear direction for process improvement.

the other side.

After obtaining the latest version of magnetron sputtering technology, Tsinghua University, the Instrument Research and Development Center of the Huazhong University of Science and Technology Association, and North Microelectronics Technology immediately began research and development work on target materials and coating equipment.

However, the first hurdle lies in the purity and microstructure uniformity of the molybdenum-silicon material.

Upon learning of this, Chen Yansen combined vacuum hot pressing sintering with plasma densification technology, immediately overcoming the bottlenecks in target material purity and structure.

Once the bottleneck was broken, subsequent research and development proceeded smoothly, like opening up the Ren and Du meridians.

The development of the lighting system is progressing by leaps and bounds!
(End of this chapter)