Chapter One Hundred and Four

As the saying goes, mathematics, physics and chemistry are not separated.

Gu Lu is a double doctor of mathematics and physics, and there is no reason why chemistry can be so bad.

The preparation of nano cerium dioxide powder is very simple.

First, a certain amount of Ce(NO3)3-6H2O and hexamethylenetetramine were weighed and configured into a 1:5 mixture.

In the second step, the mixture is placed in a 75 degrees Celsius constant temperature tank in a water bath for half an hour.

In the third step, the pellet is aged at room temperature and separated by centrifugation.

In the last step, the precipitate is washed and placed in a vacuum drying oven and dried at 80 degrees Celsius.

In this way, after the above four steps, nano cerium dioxide ultrafine powder can be obtained.

The cerium dioxide powder is spherical in shape, and the diameter particle distribution is relatively uniform, and the diameter particle is about 10 nanometers.

What's more, cerium dioxide is softer and more suitable as a polishing abrasive.

Putting on a white lab coat, gloves and masks, Gu Lu started the operation in an orderly manner.

Nearly an hour later, Gu Lu walked out of the room carrying a blue plastic bottle.

"Mr. Gu, how is it?" Manager Lin, who had been waiting outside the door, stepped forward and asked.

"Everything went well. Gu Lu took off his mask and handed the plastic bottle in his hand to Manager Zhang with a smile, "I'll change out of the lab coat, and then we'll go downstairs to the workshop to try the effect." ”

............

A few minutes later, Gu Lu and Manager Zhang walked into the workshop again.

Master Huang held a silicon wafer board and walked over with a wry smile, "As Mr. Gu said, the accuracy test this time is the same as before, and the surface roughness is above 1 nanometer. ”

Gu Lu took the silicon wafer, flipped it in his hand and looked at it carefully, then felt the touch with his fingers, and nodded, "It should be the reason for the polishing liquid, it just so happens that the cerium dioxide polishing liquid has been prepared, let's try it on the machine again." ”

"I think this time, the result will definitely be very different from the previous ones. The corners of Gu Lu's mouth rose, and there was incomparable confidence in his tone.

The polisher holds the silicon wafer, then inserts the nano-cerium dioxide powder polishing slurry, and finally, presses the start button.

The machine starts running.

Gu Lu hugged his arms and stared at the instrument.

At the same time, I kept recalling what I had read about this in the Princeton University Library.

In the process of chemical mechanical polishing of single silicon wafers, there are mainly chemical corrosion and mechanical grinding.

The removal of materials is first and foremost due to chemical corrosion. On the one hand, during the polishing process, high temperatures and pressures are generated at local contact points on the surface of the silicon wafer, resulting in a series of complex tribochemical reactions.

Nano-cerium dioxide polishing slurry, which has a higher alkaline composition and softer nano-abrasive particles.

Under the action of these two, a corrosive soft layer is formed on the surface of the silicon wafer, so as to effectively weaken the scribing effect of the abrasive on the silicon wafer matrix, improve the polishing efficiency and polishing surface quality, and correspondingly, improve the accuracy of the polished silicon wafer.

............

Half an hour passed in a blink of an eye.

The sound of the machine rubbing against the silicon wafer gradually decreases until it disappears.

After the equipment stopped, Manager Zhang and Master Huang looked at Gu Lu in unison.

Gu Lu smiled, "Take it out." ”

Master Huang carefully takes out the silicon wafers made by using cerium dioxide polishing slurry.

"What equipment do you use to look at it?" Gu Lu glanced at it and found that there was no equipment such as a microscope here.

"There's an atomic force microscope upstairs. Manager Zhang smiled and spoke.

Atomic force microscopy?

Gu Lu knew that this thing seemed to be very expensive.

I went back to the five-story building again, but the atomic force microscope was on the first floor, so I didn't have to climb the building.

Walking into the small room of more than ten square meters, Gu Lu saw the atomic force microscope that Manager Zhang said at a glance.

"Mutimode SPM version of the atomic force microscope produced by MI DI Company?" Gu Lu, who had been in the laboratory for a while, recognized it at a glance.

"You bought it?" Gu Lu turned his head to look at Manager Zhang.

As far as he knows, this microscope is not cheap, and the market price is about two or three hundred thousand yuan!

Even most university laboratories can't afford this equipment.

Manager Zhang smiled bitterly and shook his head, "Rented." ”

Gu Lu: "......"

Well, seeing that this company is distressed to even buy more than 200,000 polishing machine equipment, it is almost impossible for them to buy a microscope of more than 200,000 yuan.

But if you rent...... It doesn't seem to be cheap!

Gu Lu took a closer look at the microscope.

"It's a defective product. Before Gu Lu could see anything, Manager Zhang took the initiative to ask Gu Lu to explain, "This one is eliminated, a few hundred yuan a year, very cheap, so we rented it." ”

Gu Lu: "......"

It's really unashamed to admit it directly.

Manager Zhang doesn't seem to care about admitting the fact that his company is poor.

"Ahem. Gu Lu coughed awkwardly, "Let's hurry up and take a look at the data." ”

"Mr. Gu, I'm coming, or you're coming. Master Huang held the silicon wafer in both hands.

Gu Lu put on his gloves and rubbed his hands, "I'll come." ”

Atomic force microscope, after returning to China, Gu Lu has not touched it for a long time.

finally had this opportunity, Gu Lu still wanted to get over it.

Gu Lu pulled over a chair and sat down with a faint expectation on his face.

Then turn on the light source and carefully move the microscope in front of you.

However, Gu Lu soon regretted it.

No wonder Manager Zhang said that this microscope is a defective product.

It's so damn so bad!

Gu Lu moved the probe here, and the monitor was stuck for nearly thirty seconds before a data popped up.

Move it, the card is thirty seconds, move it, the card is thirty seconds.

In the past thirty seconds, Gu Lu stared at the flashing monitor.

Just debugging the equipment, Gu Lu took more than ten minutes.

"Mr. Gu, this monitor is a bit less sensitive, so sometimes, you have to use some traditional violent means. Master Huang sneered on the side, then stepped forward, formed a palm in his right hand, and slammed it on the monitor.

Bang——!

A dull sound sounded, and after the monitor blurred for a moment, the latest data instantly appeared.

Gu Lu: "......"

This way is indeed traditional enough!

What should I do if the monitor is stuck, most of it is underbeaten, just shoot it!

So, in the slightly closed room, there was a picture of Gu Lu slapping the monitor.

After tossing and turning with the display for half an hour, the data of this silicon wafer was finally displayed on the screen.

Ra=0.089，RMS=0.113.

In the range of 1 micron * 1 micron, the roughness of the microscopic surface is reduced to a staggering 0.089 nanometers.

This is a 12-fold reduction from the previous lowest value of 1.06 nm!

............

PS: Make a reservation for tomorrow's recommended ticket!