"Modern photolithography technology is divided into several steps. The first is vapor deposition, which means that the silicon wafer is cleaned and baked and first goes through processes such as immersion, spraying or chemical vapor deposition.
Then there is spin coating. After the base film is formed, the surface of the silicon wafer must be evenly covered with photoresist. At this time, the silicon wafer is placed on the vacuum suction cup. The bottom of the suction cup is connected to the rotating motor. When the silicon wafer is stationary or rotates very slowly,
At this time, the photoresist is dropped onto the silicon wafer, and then the
The silicon wafer is rotated to a certain speed, and the photoresist is stretched to the entire silicon wafer surface with the help of centrifugal force, and the excess photoresist is continuously rotated to get a uniform photoresist film covering layer on the silicon wafer. The rotation continues
Stop when the solvent evaporates and the photoresist film is almost dry.
Then there is soft baking. After applying the photoresist, the silicon wafer needs to be soft baked to remove the residual solvent in the photoresist and improve the adhesion and uniformity of the photoresist. Photoresist that has not been soft baked
It is easy to be sticky and contaminated by particles, and the adhesion force will be insufficient. It will also cause dissolution differences during development due to excessive solvent content, making it difficult to distinguish between exposed and unexposed photoresist.
There is also exposure. This process is to align and focus the silicon wafer surface with the quartz mask, then use ultraviolet light to irradiate the photoresist that is not blocked by the mask. An exposure reaction occurs, and the circuit diagram is transferred from the mask to the silicon wafer.
transfer.
Development is the use of chemical developers to dissolve the photoresist soluble areas caused by exposure, so that visible patterns appear on the silicon wafer, and to distinguish the areas that need to be etched and the areas protected by the photoresist. After development is completed, it is rotated and shaken
Remove excess developer, rinse with high-purity water and spin dry.
Hard film. The heat baking after development is called hard film baking. The temperature is higher than soft baking. The purpose is to evaporate the remaining solvent to harden the photoresist and improve the adhesion of the photoresist to the silicon wafer surface. This step
The stability of the photoresist is very critical for subsequent etching and other processes.
After the mold is established, there is etching. This process is very important. It is a process of selectively removing unnecessary materials from the surface of the silicon wafer through chemical or physical methods. Through etching, the desired electronic device can be built on the silicon wafer.
The last step is to remove the photoresist. After the etching is completed, the remaining photoresist on the surface of the silicon wafer is washed away with a specific solvent. At this time, a small chip is basically completed!"
Chengxian explained the working principle of this photolithography machine very clearly, which made Zhou Ming feel refreshed.
"It's really amazing. Our engraving machine doesn't have so many structures. No wonder they are so powerful. We can't compare with these small details!"
As a scientist, Professor Zhou Ming only takes the truth seriously. If the United States is stronger, it is stronger. If you don't admit it, you are deceiving yourself. Unlike some people, if others don't admit that they are stronger than you, such an attitude will never make progress.
"Comrade from the Navy, you have been exposed to this production line for the longest time. Do you have any ideas on how to improve it?"
Zhou Ming looked at Wang Haijun and asked.
When Wang Haijun heard this, his head shook like a rattle.
"Do I have a method? If I had a method, I would be a god!"
"Professor Zhou, I don't have any method. I don't even know the components in the lithography machine!"
Wang Haijun said truthfully.
"Well, I have no idea. This kind of equipment cannot be figured out by just a few people. It seems that I have to find someone. Maybe those guys can help!"
Zhou Ming said.
"Who? Professor Zhou, tell me quickly!"
Liu Lang asked quickly, and the others' eyes lit up.
"Twenty years ago, our country established an optical equipment development group, but now they are all a bunch of old guys!"
Zhou Ming made a phone call.
"Lao Xie! I am Zhou Ming!"
It was a few days after Zhou Ming made the call. It was not that he wasted time, but that the other party was too busy and was not available after several calls. In the end, the other party called.
"Old Zhou, I know it's you...Old Zhou, why did you end up in Shanghai when you weren't attending classes at Huaxia University?"
The other party asked with a smile.
Liu Lang was next to him, and he knew that the other person's name was Xie Xide. He was now the chief engineer of the Third Transistor Factory in the capital. This transistor factory is now the largest factory in the country, with an annual output of more than 10 million transistors. Most of the domestically produced radios in the country have
Transistors are all products of this factory, and Xie Xide, like Professor Zhou Ming, is also a semiconductor expert who returned from abroad in the early 1950s. The two are also old friends for more than 20 years.
"Thank you! Hasn't an electronics industrial park been established in Shanghai? That's what I'm preparing for in Shanghai!"
Zhou Ming replied.
"Huh, Shanghai has established an electronics industrial park? Why is Shanghai not the capital? The capital is not bad, right?"
When Xie Xide heard this, his tone suddenly became a little unkind.
"Haha, Lao Xie! That's the country's decision, not something you or I can say. Besides, Shanghai and the capital are all the same. It's all for our country! Look at me, aren't teachers from Huaxia University here too?
Are you here?"
Zhou Ming smiled.
"You are a good guy...Okay, why are you so anxious to see me?"
"A good thing, I just invite you to come and have a look at the Shanghai Stock Exchange!"
Zhou Ming said.
"Look? I don't know you, a good old man. You are dull, but you have a lot of tricks. You asked me to come over to help, right?"
"I'm bored, but you're so smart. There are a lot of things I can't do, so I asked you to come over and take a look!"
Zhou Ming was very polite to Xie Xide.
"I don't have time. I still have a lot of work on my hands! If I don't go, I won't go!"
The other party answered.
"Something else! Lao Xie, we have a wafer production line made by islanders here. If you don't come, you will miss it!"
Zhou Ming said calmly.
"Bah! How dare you talk about this production line? When the country bought this set of equipment from the island country, our factory was the first to propose it, but it was snatched away by that... Jiangnan Radio Factory. They
What's there? If you don't have the people you need, what will be the result? Nothing has been produced for so many years, and the country's funds have been wasted. Now you are telling me about this matter... you won't go, you won't go at all!
"
The other party was anxious at that time.
Liu Lang listened amusedly. Zhou Ming told him about this matter. When this equipment was introduced five years ago, several companies wanted it. The Capital Third Transistor Factory, as the largest semiconductor company in the country, of course
We hope to introduce this world-advanced production line, but this equipment is too expensive, worth tens of millions of dollars. Although the state will provide certain subsidies, the company itself will also have to spend more than 100 million yuan, which is too much money.
However, it is still not possible to rely on enterprises alone, and we can only rely on the help of local governments.
The capital did not contribute the money. Instead, the Jiangnan Radio Factory used the money to buy this production line. However, although Jiangnan Radio Factory obtained this set of equipment, no one could actually operate it. After one year of production, it failed due to
The market was not good and work was stopped. It was put away for several years. If it were not for Wang Haijun and several other people to maintain it every month, this set of equipment would probably be scrapped.
From this incident, it can be seen that there is no unified plan for the layout of the national industry. A set of equipment is bought before knowing whether it can be used. After buying it, I don’t know who will use it, otherwise Liu Lang will not
The concept of industrial park will be proposed.
This incident has always bothered Xie Xide, so he became anxious when he heard about it.