Chapter 843 Wait! I might have a solution

The effect of this report was achieved. Tang Shaohui smiled as he packed up his things: "I see. You know what, the velvet surface made with this method is really beautiful, shiny black, and much deeper than the blue surface made by photolithography."

A black color indicates low reflectivity and good light-trapping properties, provided that the black color is not achieved through other means.

Low-cost technology is not necessarily worse than high-cost technology, provided that the right approach is taken.

Shiny black?! Huh??

When Gao Zhendong heard this adjective, he suddenly remembered something.

Black velvet board?
If you had told me this earlier, I wouldn't be so sleepy. I remember seeing this thing somewhere.

Gao Zhendong immediately started searching in his mind, and yes, that’s it!

Before Tang Shaohui walked out of Gao Zhendong's office, he heard Gao Zhendong calling him.

"Wait, what's the problem with your process? Tell me about it."

Ok?
Tang Shaohui immediately turned around excitedly. Chief Engineer Gao held him back. There must be a reason. Maybe he had thought of a solution!
As for how Gao Zhendong came up with a solution when he didn't even know the problem, that is another matter. Chief Engineer Gao's affairs are different from those of ordinary people.

Tang Shaohui walked back excitedly and sat down, taking out some other materials that he was going to take to the laboratory to work. He had not originally planned to report on these materials.

"The problem now is that the reaction speed is too fast! Once the speed is fast, it is difficult to control. This speed exists in both the hole opening and hole expansion stages. At the same time, we observed that there is another problem, that is, bubbles. During the reaction process, bubbles are generated. These bubbles will adhere to the silicon wafer, affecting the reaction and the uniformity of the reaction."

After Gao Zhendong heard this, he stretched out his hand and said, "Show me your current craftsmanship."

Tang Shaohui quickly found the process documents and handed them to Gao Zhendong.

Gao Zhendong looked at the process documents without saying anything. He sat on the sofa without saying a word, but he didn't ask Tang Shaohui to leave either.

In Tang Shaohui's opinion, Chief Engineer Gao must be thinking quickly in his head and trying to come up with a plan at this moment.

He guessed half right. Gao Zhendong was thinking of a move, but he was not thinking quickly. He was looking at a document, which was a process document for making black velvet. The process had more than 20 steps and it was a complete one.

After a long time, Gao Zhendong looked at Tang Shaohui.

"During the hole digging stage, you add about 25% hydrogen peroxide and about 1% soluble silicate to the hydrofluoric acid."

In fact, there is more than one formula for these additives in the process documents, but some of the formulas are too complicated and difficult to obtain under current conditions. Things like biological enzymes, fatty acid amides, and acid-alcohol compounds are somewhat beyond the scope of current conditions.

The formula chosen by Gao Zhendong is much simpler. Hydrogen peroxide and soluble silicates are not strange things. You can use a handful of them and the effect is not bad.

Hydrogen peroxide? Soluble silicates?

Although Tang Shaohui discovered this phenomenon, he did not study chemistry and had no ability to study these phenomena. The research work was done in cooperation with teachers and professors of chemistry. He heard Gao Zhendong's proposal clearly, but was far from understanding it.

"Chief Engineer Gao, what are the uses of these things? Please tell me about them. I don't know much about them. I'll write them down and when I tell them to my comrades in chemistry, they will be able to grasp your ideas early and do their work more smoothly." If you don't understand, just ask.

At this time, Tang Shaohui was full of admiration for Gao Zhendong. He listened, thought about it, and gave a plan. No matter whether it could be used or not, his confidence was real.

Tang Shaohui had a hunch that the plan proposed by Chief Engineer Gao was more or less effective.

"Let's talk about silicate first. The main reason for adding it is that it reacts with hydrofluoric acid to generate silicate, which can inhibit the speed of the corrosion reaction and solve the problem of the excessive reaction speed you mentioned."

Tang Shaohui took notes and said with a smile, "Oh, I see. It's just competing with the reaction for raw materials. I see." Chief Engineer Gao explained it simply and clearly. It was easy to understand. The simplest way is the best.

Gao Zhendong smiled and nodded: "Yes, that's the truth. As for hydrogen peroxide, it solves two problems. One is to promote the reaction and increase the depth of the hole. The second is to use the easy decomposition of hydrogen peroxide to promote the detachment of bubbles from the surface of the silicon wafer and solve the bubble problem you mentioned."

Tang Shaohui quickly wrote it down. It all sounded very reasonable. He didn't know how Chief Engineer Gao came up with this idea after just a short while of thinking about it.

However, remembering the book of organic chemistry he had just seen on Chief Engineer Gao's desk, he seemed to understand that Chief Engineer Gao had been studying non-stop. As for how much connection there was between organic chemistry and inorganic chemistry, that didn't matter, as they were all chemistry anyway.

"As for the reaction speed of hole expansion, let's put it aside for now. Don't you have a silver removal process? Add hydrogen peroxide!"

Gao Zhendong has somewhat deceived Tang Shaohui. He adds hydrogen peroxide to everything, right?

"In this step, the easily decomposable nature of hydrogen peroxide produces bubbles that rinse the silicon wafer, which can more cleanly remove the silver element and silver ions. At the same time, the silver hydroxide generated by silver ions and hydrogen peroxide is unstable and easily decomposes to form water and silver oxide, which can also help remove the deposited silver ions."

In such a short time, Tang Shaohui and his chemistry colleagues could not think so far, so Gao Zhendong simply made up for their shortcomings. Tang Shaohui was confused. Well, it seemed to make sense.

"You just mentioned that the reaction speed in the hole expansion stage is too fast, which can easily cause the concave hole to be too large, and the reflectivity will increase. For this problem, you should add hydrogen peroxide, because this step not only has a weak acid like hydrofluoric acid, but also a strong acid like nitric acid. At this time, hydrogen peroxide can inhibit the reaction speed."

It's hydrogen peroxide again! Tang Shaohui was completely numb.

Hydrogen peroxide is a panacea, right?

Gao Zhendong added: "But you have to pay attention to one thing. Too low a reflectivity is not a good thing. It will cause a hot spot effect, which will make things worse."

At this point, he remembered something: "By the way, if the debubbling effect is still not good, you can use ultrasonic waves of tens of thousands of Hz to impact the silicon wafer every once in a while, such as tens of seconds, for a few seconds. You can adjust the specific time during the experiment. But remember, you can't impact continuously, which will affect the hole digging and hole expansion reaction."

This is easy to understand. Use ultrasound to shake the silicon wafer to shake off the bubbles. Tang Shaohui obeyed the impact and recorded it truthfully.

As for other things, Gao Zhendong did not interfere too much. The process documents in his hands might not be the most appropriate ones at the moment. It was enough to solve the core problems. It was better to let the comrades explore the rest on their own under the existing environment.

Tang Shaohui was stunned by Gao Zhendong's three consecutive shots of hydrogen peroxide. He was still a little dazed when he returned to the laboratory.

A comrade from the chemistry major who came to support the research team from a university came up to him excitedly when he saw him come back.

"Engineer Tang, how was the report? Did Chief Engineer Gao agree that we should go the Shenyin route?"

Tang Shaohui nodded: "I agreed, and he also gave me several solutions to the current process problems. Come, Mr. Gou, take a look."

Teacher Gou was pleasantly surprised by these words. It was just a report, but there was an unexpected surprise. To be honest, they had never thought that Chief Engineer Gao could solve the problem in chemical engineering. After all, it seemed that his expertise was too far from that of Chief Engineer Gao, so they could not count on it.

War Drum-2 Missile: Guess who developed the mass production process for my unsymmetrical dimethylhydrazine fuel?
"Really? Let me see it quickly." Teacher Gou did not underestimate Gao Zhendong's idea just because he was not studying chemistry. For a technician at the third level who is less than 30 years old, it is not surprising that he can do anything technically.

Tang Shaohui, who was still confused by Gao Zhendong's three consecutive hits, handed what he had written down to Teacher Gou.

When Teacher Gou took his first look, he was stunned, just like Tang Shaohui.

"Hydrogen peroxide? Hydrogen peroxide again? Or hydrogen peroxide? Oh, there's a little silicate in the first step."

But when he carefully read and analyzed the other things that Tang Shaohui had written down, the joy on his face grew stronger and stronger, and in the end, he could hardly hide the smile on the corners of his mouth.

Although Chief Engineer Gao's three consecutive hydrogen peroxide injections seem a bit outrageous, upon closer inspection, it seems to be true, at least it seems to be correct.

The final operation of removing bubbles by ultrasonic impact made his eyes light up. If both chemical and physical methods are used together, one of them will always be effective.

"Oh, Mr. Tang, thank you so much. Your report may save us a lot of trouble." Teacher Gou said happily.

"Do you think you can do it?"

"I think it's really feasible. I can't say it's completely effective, but at least some of it is effective, which is amazing," said Teacher Gou.

After saying that, he turned around and called to his students: "Come on, get some hydrogen peroxide, and let's give it a try according to this process requirement! Let's do the experiment."

Although there is no hydrogen peroxide in the laboratory, this thing is not uncommon and was once often used as a disinfectant.

Fortunately, the reaction time of silver immersion hole expansion is not too long, and each process takes only a few minutes at most.

Two hours later, Teacher Gou and Tang Shaohui looked at a pitch-black silicon wafer in front of them with surprised expressions on their faces. No matter whether it succeeded or not, at least it didn't look any worse.

There was more than one silicon wafer in a batch, and the others were sent for testing.

The two of them placed the silicon wafer under the microscope, and Teacher Gou put his eyes close to it.

After a minute, he was all smiles and called out to Tang Shaohui: "Mr. Tang, come and see!"

Tang Shaohui put his eyes closer and looked under the microscope. The size of the small pits seemed to be basically consistent with the requirements, and most importantly, they were very uniform.

"Teacher, teacher, the reflectivity meets the requirements!" The voice of Teacher Gou's students also rang out at this time.

(End of this chapter)