Chapter 526 We Workers Have Power

The worktable heats the silicon wafer again, giving the workpiece a hard coating, reinforcing the retained photoresist and further removing the unnecessary glue and residues of other components.

After the hardening film was completed, the silicon wafer was started again from the beginning and the second photolithography process began, using the same standard mask.

After the development is completed, the photoresist of the secondary lithography is cured, the excess parts are removed, and the silicon wafer is sent under a microscope.

As soon as the clear microscopic image of the silicon wafer surface popped up, Ma Juan exclaimed with joy.

"Brother, I got it, I can see it, the accuracy is so high!"

Ma Juan shouted while looking into the microscope.

Gao Zhendong had anticipated the high overlay accuracy. The workpiece table is the main factor that determines the overlay accuracy. However, a group of experienced craftsmen at the third rolling mill showed their prowess and reduced the positioning accuracy of the workpiece table to 1.5μm.

The optical system image distortion of the Northeast Institute of Optics is less than 1 μm. Combining these two, the overlay accuracy will definitely not be bad.

However, estimates are just estimates. No one can completely relax until they see the real results.

Hearing Ma Juan's words, Gao Zhendong laughed: "Come on, let me take a look."

Ma Juan moved away from the microscope, and Gao Zhendong put his eyes close to the eyepiece of the microscope. He could even see his own eyelashes through the microscope, but he obviously didn't have the leisure to observe whether his eyelashes looked good or not, and was eager to look into the field of view.

Under the microscope, the traces of the two photolithography lines are very obvious, one superimposed on the other, with a very high degree of overlap.

The traces of the two photolithography processes leave a small part exposed on each side. The single-side width of this part is basically the overlay error. At a rough glance, it is less than half of the entire line width.

"Good! Great! Ma Juan, select some typical points, cover the entire silicon wafer, and make a more comprehensive measurement comparison immediately."

Another tester came up and worked with Ma Juan to find points, measure and record.

The theory of relativity of time is fully reflected here. Ma Juan and others feel that time passes very quickly, while Gao Zhendong and others who are waiting for the results feel that time passes too slowly.

After a period of time that was both fast and slow passed, the experimenters sat down in front of the computer and began to input the data into the computer. For this simple statistical analysis, they typed the data directly in the source code.

The C code for the processing algorithm has already been written, and now they are just filling an array with data.

The advantage of this method is that the processing algorithm can be modified at any time according to needs.

The sound of keyboards clacking away calmed the people on site. Judging from the numbers they had just measured and reported, the result would not be too bad.

As the last piece of data was entered, Ma Juan started the compile-run command.

The algorithm was too simple to cause any debugging trouble, and soon a number popped up on the screen.

Anyone who has written a temporary program knows that it is best to keep it as simple as possible. This number does not even have any units.

"1.97".

In fact, one decimal place is enough. The unit that is not written is μm.

2μm!

Although he had expected it, Gao Zhendong still burst into laughter when the number popped up.

"Hahaha...Okay! Great!"

This overlay accuracy has exceeded the current requirements. The PMOS has a small number of overlay times. In fact, strictly speaking, at a resolution of 10μm, an overlay accuracy of 5μm is sufficient.

Now, Gao Zhendong can directly announce that the line width of our first-generation PMOS process integrated circuit is 10μm.

This line width doesn't sound very good, but you can see its usefulness from an example. The prototype of DJS-59, the golden C8008, uses the 10μm-PMOS process! There are more than 6000 transistors on that small chip.

The first 4Kbit (512Byte) DRAM was produced using the 8μm-NMOS process. Although it is NMOS, it does not mean that only NMOS can be used for DRAM. The biggest difference between PMOS and NMOS is that the switching directions are opposite, and the switching speed of NMOS is about 2.5 times faster than that of PMOS.

But this was 61, and a slower PMOS didn’t mean it couldn’t be used.

Unfortunately, when the two chips appeared, Gao Zhendong was still unable to lock in the exchange capability. But it didn’t matter. As I said before, in the early stages of the industry, it was enough to just make do with a simple design, and the core design was not difficult.

The transistor circuit of DJS-59 is actually basically the same as that of C8008. What Gao Zhendong needs to do now is to restore this structure to the photolithography mask.

However, this is a strenuous job and Gao Zhendong cannot do it alone. It is a waste of time. So this task falls on the shoulders of some senior students of Beijing University of Technology.

Originally, Gao Zhendong was not too optimistic about the lithography machine, and initially estimated it to be around 50μm. Later, after seeing how powerful the masters at the Third Rolling Mill and the Northeast Institute of Optics were, he changed the first three chips of the SZ61XXX series chips to 20μm.

Now there is a solid hope for 10μm, which makes me extremely happy. Even if I have to teach students for half a year and then draw pictures for one or two years, there is only one word to describe it - worth it!
And with these basics, there are many things you can do, such as the favorite of automation people - the single-chip microcomputer.

However, whether it is the CPU-based DJS-59 or the single-chip microcomputer, it will take time, and we have to wait for at least two things.

——The real maturity of integrated circuit technology and the complete design of chips. Especially the single-chip microcomputer, which looks similar to a general-purpose CPU, but at the current computing speed, it is better to use another structure - the Harvard structure.

Compared with the von Neumann structure, this structure is more efficient.

These are all later matters. The current priority is to invest photolithography machines into integrated circuit technology and make the entire integrated circuit technology mature as soon as possible, at least to produce a certain number of basic digital logic chips for everyone to use.

Even though this thing is basically all handmade, the output is not low for that era. Of course, it cannot be compared with the fully automatic photolithography production lines of later generations.

According to a rough calculation that a logic circuit chip uses a 5mm*5mm silicon wafer area, a 130mm wafer can produce 500 chips.

Don't underestimate the small area of ​​5*5. In fact, under the 10μm process, it can almost produce digital logic chips similar to the entire 74 series. The part of most digital logic chips that consumes the most silicon wafer area is actually the crimping points where the circuit leads out.

If CPU and single-chip microcomputer are still a little far away, then for most commonly used digital logic circuits, at this stage, the main constraint is how fast the chip is designed. After all, the family of digital logic circuits is really huge.

Gao Zhendong had already made arrangements for this matter.

Wearing protective clothing and being in a clean room, it was not convenient for Gao Zhendong to announce that the prototype had been successful.

Looking at the anxious colleagues in the lithography machine research team outside the glass window, Gao Zhendong, who couldn't bear to see them wait for a long time, suddenly had an idea. He picked up a pen and paper and wrote down three big words.

"Success!"

Gao Zhendong picked up the paper and showed it to all the comrades in the clean room and outside.

If the comrades in the clean room seemed calm because they had anticipated the result, then the comrades outside the window who were in the dark due to information asymmetry cheered when they saw these three words.

"It's done!"

"Finally it worked!"

"This thing is very important, right? Look how worried Chief Engineer Gao is about it."

"No, I think this is at least another science and technology award."

"I never thought that after spending my whole life turning metal lumps, I could still do science in my old age."

"I didn't expect that. After all this noise all my life, I still don't believe that I have a share in this thing."

"You are just too narrow-minded. Didn't you hear what the higher-ups said? We have plenty of power."

"Yes, yes, you are so careless. Then why are your hands shaking? We have been friends for decades, and we know each other."

The comrades outside were talking and laughing. I don't know who started it, but they slowly started singing a song in unison.

"We workers have power, oh, we workers have power..."

"..."

"The world has changed a lot because of the transformation, hey!"

"..."

"To seek liberation! Hey~hey! Hey~hey!"

"..."

There are men and women, young and old, singing, some holding hammers, some holding books, some standing by machines, some sitting in front of computers...

The concise, clear and powerful singing rang out in the trial production workshop of the lithography machine, shaking the walls.

As the last shout of "Hey!" rang out, all the comrades stood together, looked at Gao Zhendong, and applauded enthusiastically.

Gao Zhendong's face was full of joy. After everyone calmed down a little, he signaled the experimenters to shut down the equipment and finish the work, then walked into the cubicle and took off their protective clothing.

After coming out of the clean room, Gao Zhendong arranged for a comrade to arrange for dinner. The rules cannot be broken. Even if they can only eat coarse food, they have to have a meal together, not to mention that it is much better than eating coarse food now.

Then he turned to Ma Juan and said, "Ma Juan, continue to do a few more tests to see how stable it is. Then you and Master Yi will prepare. This equipment will need to be moved. In addition to preparing for the move, your entire team must also prepare. The core members will go to the relevant brother factories to provide support for a period of time."

The next thing, naturally, is to move the equipment to Factory 1274, where it will be directly integrated into the entire integrated circuit process as a key node.

During this process, all the core members of the research team who are responsible for manufacturing, installation, debugging and use of the lithography machine have to be stationed in Factory 1274 to deal with various environmental problems and emergencies. They can only be withdrawn until the comrades in Factory 1274 have become proficient in using the lithography machine.

The two nodded in agreement. Gao Zhendong looked at his comrades and said, "Well, although everyone knows this, I will still make an official announcement. Haha, the GK-61 proximity 10μm lithography machine has been successful! Comrades, you have worked hard! Now let's enjoy the joy of success. It's the same old rules for lunch. You all know it."

(End of this chapter)