Super Copy of Great Power Technology

They could only wait until tomorrow after the machine was turned on for production testing, and then slowly remind them. Everyone waited in the chip laboratory for more than an hour until the photolithography machine was installed. Only then did they reluctantly leave the laboratory and go their separate ways. According to their wishes, they wanted to start the production line and conduct photolithography testing that night. However, this was Rockchip Fab, not their team's laboratory in Beijing. When to start the chip production line and when to test the photolithography machine had to be decided by the person in charge of Rockchip Fab.

The next day, Qiao Ruida came to Rockchip again and joined Academician Wang, Academician Yao and others. They put on cleanroom clothes and entered the chip laboratory. Dozens of researchers from Rockchip, led by Lin Mengsong, entered the laboratory earlier than them and were busy on the chip production line, preheating the machines, preparing materials, and adjusting the parameters of some equipment to prepare for the next lithography machine test.

Qiao Ruida walked to Lin Mengsong and asked, "Director Lin, how are the preparations going?"

Hearing the voice, Lin Mengsong turned around and saw that it was Qiao Ruida. He nodded and greeted, "Mr. Qiao, you are here. Everything is ready and you can start the test at any time."

Qiao Ruida nodded with satisfaction and said, "Okay, let's get started right away. Those academicians can't wait any longer. By the way, what kind of graphene chips do you plan to produce for testing?"

"I have prepared a graphene memory chip and a communication chip, and two masks for lithography testing. This is the simplest graphene chip we have. If this doesn't work, it will be even more difficult to succeed with other more complex chips."

"Then let's choose memory chips. Let's start with 20 of them and see if this newly developed graphene wafer lithography machine can produce qualified chips."

"Okay, Mr. Qiao, we'll start production now." Lin Mengsong agreed, then walked to the main control console and personally started the graphene chip experimental production line.

The next moment, the machinery started to move, the overhead crane sped, and the entire production line started running. Graphene wafers were constantly transferred between production equipment through conveyor belts and manipulators, undergoing one process after another. The production process of graphene chips is very complicated and time-consuming, and the photolithography process is relatively late. It takes at least two hours before the new photolithography machine can be put on the stage for testing.

Qiao Ruida had nothing to do and almost dozed off standing there. However, most of the members of the R&D team, led by the academicians, saw the complete graphene chip production process for the first time and were quite curious. Dozens of people followed the batch of graphene wafers being processed, passing one device after another, watching them very carefully, afraid of missing any details.

"Old Wang, I heard that your Peking University chip laboratory also has a graphene chip experimental production line. How does it compare with this production line?" Academician Yao nudged Academician Wang next to him with his shoulder and asked.

"Almost the same. Our production line was also donated to the school by Qiao Ruida. The equipment solutions are similar, but the production capacity is slightly higher. It is enough to meet the wafer flow needs of our teachers and students. Occasionally, we can also undertake some graphene chip wafer flow and testing business to subsidize the experimental expenses." Speaking of the graphene chip production line of his own school, Academician Wang is quite proud. You know, there are only two places in the world that can produce mature graphene chips. One of them is naturally Rockchip Wafer Factory, and the other place is the Peking University Chip Laboratory led by him.

"Other students take advantage of their supervisors to get equipment and funding, but with you, it's the other way around. It's the students who provide equipment and technology to their supervisors. You should be proud of yourself. With Qiao Ruida as your disciple, you really have everything you want."

"Haha, Lao Yao, why are you so sarcastic? Qiao Ruida was able to study at Peking University and become my graduate student because of our efforts. There is only one such talented student like Qiao Ruida in decades. You can't envy him even if you envy him."

The academicians and researchers had never seen the production process of graphene chips, so they watched it with great interest. However, Qiao Ruida had seen the same scene dozens or hundreds of times, and he was not interested at all. After two hours of boredom, twenty graphene wafers for testing went through dozens of processes and finally came to the photolithography process.

Qiao Ruida pulled himself together and followed several academicians to the orange-painted lithography machine. A researcher from Rockchip Foundry handed a container full of graphene wafers to Academician Wang and said, "Academician Yao, all the graphene wafers for testing are here, a total of 20 pieces, not one less. All the previous processes have been completed, and now it depends on the performance of this lithography machine."

Academician Yao took the graphene wafer, hesitated for a moment, and then said to Academician Wang: "Old Wang, you usually use the lithography machine the most and have the most experience. Why don't we let you operate this lithography machine!"

"Okay, then let me do it. With my help, it will definitely be successful!"

Academician Wang took the graphene wafer box and walked to the operating position confidently. He opened the box and used a special fixture to take out the graphene wafers in the box one by one and put them on the incoming tray of the lithography machine. Then he installed the graphene memory chip mask provided by Lin Mengsong, took a deep breath, and pressed the power button. With a series of light drips and flashing indicator lights, the equipment began to self-check, checking whether all components were installed in place, whether all materials used in lithography production were complete, and preheating the light source department.

Different types of lithography machines use very different light sources. For example, the light source used by DUV lithography machines is a 193nm deep ultraviolet light source. EUV lithography machines use an extreme ultraviolet light source with a wavelength of 13.5nm. The graphene lithography machine goes a step further and uses a 6.6nm FEL light source. Theoretically, its ultimate processing accuracy is much smaller than that of the EUV lithography machine. Of course, the graphene mobile phone chips and graphene notebook processors currently launched by Reda Technology are far from reaching the ultimate processing accuracy of lithography machines. One is that the existing equipment is immature and cannot reach the theoretical ultimate processing accuracy, and the other is that there is no need to pursue such an extreme. Compared with traditional silicon-based chips, the performance of graphene chips is really too powerful and the heat generation is very low. Even if a processing technology of more than ten NM is used, the mobile phone chips produced are far ahead of silicon-based mobile phone chips. Before competitors master the production technology of graphene chips, there is no need to come up with overly advanced products.

A few minutes later, a long beep sounded, the lithography machine self-checked and ended, the intelligent control program started, and two graphene wafers were "swallowed" by the lithography machine one after another. Clamped by the precision mechanical arm, they were accurately placed on the double worktable. Then the special fastener locked the wafer, the light inside the equipment kept flashing, and the lithography process officially started.

The graphene memory chips processed this time have a relatively low process technology and a relatively simple structure. The photolithography process is almost done in one pass, and there is no need for complex operations such as overlay and 3D accumulation. Therefore, the processing speed is extremely fast. The complete photolithography process of a graphene wafer only takes a few blinks of an eye. Therefore, these 20 test graphene wafers are quite useless. They were all photolithographically completed after only a few minutes of operation.

Lin Mengsong stepped forward again, collected the photolithography-finished graphene wafers, put them into a special box, and then took the box to the next process equipment to carry out the subsequent development, hard baking, etching, testing and other processes. It took an hour to go through the entire process. When entering the production line, there were twenty crystal clear graphene wafers, but what came out was a small pile of black chips. When placed in front of everyone, just looking at the appearance, it was indeed a bit disappointing to the audience. "Are the number of these memory chips too small? 20 wafers can at least process hundreds of graphene memory chips, why are there so few here?" Seeing that there was only such a small pile of finished products, Academician Yao raised his doubts.

"After the wafer is cut into chips, an initial screening is performed using optical equipment to screen out those with obvious defects. In other words, only those in front of us can reach the end and be processed into chips," said Lin Mengsong, pointing to the small pile of chips in front of him.

"So, these chips are all qualified products?"

Lin Mengsong shook his head and said, "Didn't I just say that the previous screening process is just a preliminary screening. Now these chips need to be sent to the laboratory next door for detailed testing to determine whether the chips are good or bad."

After that, Lin Mengsong put the memory chips into an anti-static bag and sent it to the chip testing laboratory next door. Then there was another long wait, until half an hour later, the test was completed, and Lin Mengsong walked into the lounge with a test report.

"The chip test is complete. Here is the test report. There are both good and bad news. Which one do you want to hear first?"

"Of course we want to hear the good news first. We have just been waiting for several hours. It would be nice to hear the good news first."

Lin Mengsong did not keep the secret and said directly: "The good news is that there are indeed qualified products among the pile of memory chips just now. In other words, the lithography machine you developed can indeed complete the lithography process of graphene wafers and produce qualified graphene chips."

Hearing this, several academicians and dozens of researchers at the scene were all excited. In the small lounge, applause and cheers rang out for a long time. The lithography machine they developed can complete the lithography process and produce qualified chips. This means that their hard work day and night in the past few months has not been in vain, and all their efforts have paid off handsomely. After returning, they will definitely get a large bonus, and promotion and salary increase are just around the corner.

When the cheers died down, someone asked weakly, "We've talked about the good news, and we've been happy about it. Now let's talk about the bad news. We can bear it."

"Well, the bad news is that out of that small pile of memory chips, only two are qualified products, and the yield rate is less than 2%. This shows that the lithography machine you developed has serious defects, and it must be fully overhauled to eliminate the problem."

As soon as Lin Mengsong finished speaking, everyone in the lounge who had been so excited just now immediately became listless.

"What? There are only two qualified chips. How can it be so few? 2 eight-inch wafers, cut into memory chips, can produce at least tens of thousands of chips. There are only two qualified products. How can it be so bad?"

"You don't know until you calculate it. Once you calculate it, you will be shocked. This is not less than 1% of the yield rate, but less than 1/1000! If the wafer factory produces chips in large quantities according to this yield rate, it will lose money."

"This is the simplest memory chip, and the result is so bad. If it is a much more complicated mobile phone chip or notebook chip, I'm afraid that not a single qualified chip can be produced."

"I suggest that the lithography machine be overhauled immediately to find out where the problem lies and solve it as soon as possible."

"Reconsideration, the product yield is so low, the equipment must have one or more major defects, it should not be difficult to find them."

"It looks like a tough battle is about to begin. We have to work overtime again. I'm afraid the New Year's Day holiday will be cancelled again."

Academician Yao clapped his hands, attracting everyone's attention, and said loudly: "Don't be discouraged, isn't it just that the chip yield is lower? It's not completely unusable. Our team has built a world-leading graphene wafer lithography machine from scratch in just a few months. Now this equipment just has some minor problems, and we need to find them one by one and repair them. This is much easier than developing a lithography machine. Why are you so dejected?"

After Academician Yao's advice, the researchers came to their senses. It was just that the product yield rate was lower, not that the project failed completely. There was no need to be depressed. As long as they were willing to work hard, find the problems, and fix the defects, the yield rate would always go back up. At most, they could just work on it for a few more months, and there would always be a moment of success.

With hope rekindled, they went to the cafeteria, had a hasty late lunch, and then went back to the laboratory to find, analyze, and solve problems around the photolithography machine. Qiao Ruida also gave them some indirect advice, which made several academicians suddenly enlightened. They quickly found several defective parts and removed them. Next, they had to redesign these problematic parts, use new materials, and adopt new processing methods to ensure that the original problems would not occur again. (End of this chapter)