As the most critical link in the chip manufacturing process, the basic principle of lithography is actually very simple, that is, to use light to complete the engraving of silicon wafers.

The silicon wafer in lithography is like a projection cloth hanging on the wall, and the lithography machine is a projector.

If the surface of the projection cloth is uneven and undulating, the projected picture will naturally be distorted.

In lithography, surface defects on the silicon wafer will cause the circuit design path on the projection to be deformed, resulting in reduced yield and even scrapping of the entire wafer.

Therefore, if you want to get a silicon wafer that can be used to make chips, you need to polish and polish the cut monocrystalline silicon wafer until its surface flatness is less than 1.5nm RMS.

This is equivalent to hanging a large curtain in a movie theater, and its surface fluctuations cannot exceed the size of a human hair, which is infinitely close to a perfect mirror.

Therefore, this is naturally extremely important for the silicon wafer manufacturing and polishing process requirements.

From the small steel balls on the tip of a ballpoint pen, to the silicon wafer, the raw material of the chip, to the lens on the lithography machine, and finally even the water droplets with a flawless surface in the sci-fi three-body problem......

In fact, the test of a civilization's industrial level is to see how fine you can make an object.

To make fine things, you naturally need a clean room with clean air, otherwise the air is full of dust and bacteria, and no matter how you polish it, you can't make qualified silicon wafers.

"In fact, over the years, we have been able to achieve the flatness of 2.6nm RMS by imitating the equipment of the island country, but no matter how much we check, even if every part has reached the standard, there is still no way to continue to break through the ......."

Yan Hui wore a protective suit while introducing the progress of their research to Kangchi.

"What kind of polishing slurry is used to throw 2.6nm RMS?"

"Based on SiO2, 0-70wt% hydrogen peroxide was added, and finally the pH was adjusted to 8.5 with KOH."

Kangchi nodded: "Let's take a look first." ”

After the two put on the protective clothing, they soon came to the polishing laboratory, and then Yan Hui presided over and demonstrated a polishing experiment to Kangchi.

In traditional silicon wafer polishing and grinding, the silicon wafer is usually preliminarily polished with a mechanical polishing machine, then cleaned, and finally chemically mechanically polished, also known as fine grinding.

Fine grinding is a kind of chemical corrosion function of polishing slurry, combined with mechanical grinding of mechanical turntable, and the two cooperate with each other to meet the process standard of silicon wafers.

The result of the experiment was 3.1nm RMS, which was much worse than the limit of what they could do.

Kang Chi pondered for a moment, and then said: "Replace it with 30wt% Al2O3 base solution, add 65wt% potassium permanganate as chemical polishing liquid, and adjust it to a pH value of 8.0 with 5wt%HNO3 and try again." ”

Yan Hui nodded, took the researchers to mix the polishing liquid, and then re-conducted the experiment.

"Flatness 5.9nm RMS."

Seeing this result, Yan Hui, who was still a little expectant, couldn't help but show a look of disappointment.

But Kangchi was still unmoved, and reported a set of polishing slurry ratios for them to re-conduct the third experiment.

"Flatness 5.9nm RMS."

5.9？

Or 5.9?!

Is it a coincidence?

Although 5.9 was obviously far from the standard, Yan Hui seemed to realize something, and turned his head to look at Kangchi in some surprise.

"You...... Calculated? ”

"Sort of."

Kangchi nodded.

Yan Hui was completely stunned at this time,

It is important to know that the technical difficulties of chemical mechanical polishing, in addition to the hardware of the polishing equipment must meet the standards, but also according to the performance of the equipment and the parameters of the silicon wafer, the chemical polishing liquid should be deployed to achieve the perfect combination of chemical polishing and mechanical polishing.

In order to debug well, you need to know the equipment well, and secondly, you need to have rich experience in polishing slurry blending.

However, with just one experimental demonstration, Kangchi was able to easily report two groups of polishing slurries with different compositions, and in subsequent experiments, the flatness of the same value was achieved......

That's a bit of a weird, isn't it?

Even Yan Hui, who has participated in countless tests, will never be able to do such accurate control without computer simulation.

The estimation error must be at least 0.3nm RMS.

He asked, somewhat incredulously, "How the hell did you do that?" ”

"Well, I can't tell...... Maybe it's some kind of intuition, I'm quite sensitive to mechanical things. ”

Kang Chi thought for a moment, and then continued,

"I estimate that the normal level of stable performance of this polishing machine should be about 3.0nm RMS, and 2.6nm RMS is only achieved by accident because of accidental factors, and it will definitely not be more than three times."

Yan Hui was stunned again, obviously guessed by Kang Chi.

"Indeed, there is only one ......"

Kangchi wanted to say something, but his stomach was already growling with hunger,

I looked at the time and found that after three rounds of experiments, it was already eight o'clock in the evening.

"I'm sorry, I didn't notice that it's so late...... Let's pack up and go eat first, you've worked hard today. ”

"Hmm." Yan Hui nodded and said, "Then everyone will finish eating and come back at nine o'clock to continue." ”

"Come back and continue?" Kangchi couldn't help but show a strange expression, "What are you going to do?" ”

"Do an experiment."

"It's useless, it's not a matter of the proportion of polishing liquid at all, you guys are doing useless work." Kang Chi shook his head directly and said, "Go home early after eating, wash and sleep, tomorrow we will come over again to dismantle the polishing machine, if I guess correctly, it is your equipment installation problem." ”

Hearing that Kang Chi had already guessed the problem, Yan Hui was suddenly a little excited: "Don't wait for tomorrow, we can carry it out and dismantle it for you now!" ”

Kang Chi glanced at Yan Hui: "I'm hungry and tired." ”

“……”

Yan Hui couldn't help but be embarrassed.

"Ahem...... Sorry, I forgot you just came from Steel City today. ”

"It's just that I didn't rush from the steel city, it's time to eat and rest at this point, you too, don't work overtime if you can work overtime in the future, although the time is urgent, but we also have to pay attention to efficiency in our work, instead of blindly piling up time, you have dizzy people, what else are you doing research?"

“……”

When I finished cleaning up the laboratory and took off my protective clothing and came to the company canteen, it was already nine o'clock in the evening.

Because the silicon wafer production department does not stop working 24 hours a day, and the scientific research dogs in the R&D and manufacturing center often work overtime all night, the company's canteen is also available 24 hours a day, and you can eat at any time.

After the aunt who was cooking in the cafeteria saw Yan Hui, her attitude was quite enthusiastic, and she put more dishes on his plate.

Kang Chi couldn't help it, and glanced at the aunt more,

Well......

Although he is a little older, he can barely be regarded as charming.

"Ahem, don't think about it." Yan Hui saw Kang Chi's complicated expression, and hurriedly coughed lightly, "If she knew that you were the big boss, she would probably fight more......"

"I didn't say anything, what are you nervous about?"

Yan Hui: "......"

……

After eating, Kang Chi contacted the company's administrative director by phone, and then under his leadership, he and Chen Hai came to the house that the company had prepared for him in advance.

It is a two-storey villa with five bedrooms and two living rooms, which is quite chic.

It's just a person who lives, and it looks a little empty and deserted.

Well

After Chen Hai sent Kangchi home, he didn't know where he went, probably in the next building?

Kangchi didn't invite him to live with him either,

Otherwise, two big men are under the same roof,

What kind of system!?

(End of chapter)