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Ziqi and Tong Xiaoyun are very interested in the process of producing CPUs. pestered Fan Wuxian to take them to visit.

"Actually, there's nothing to see, but since you want to see it, let's go for it." Fan Wuxian couldn't stand their entanglement, so he agreed.

Of course, going to see the manufacturing process of the CPU is different from watching to grow Chinese cabbage, Fan Wuxi greeted the factory in advance and asked them to arrange a convenient time.

After staying here for two days at Wang Rongchang, Fan Wuxian took Ziqi and Tong Xiaoyun to Fan's chip manufacturing base to visit the CPU manufacturing process.

Fan's chip manufacturing base, with a total investment of more than one billion US dollars, was built by 5,000 workers over two years, during which a total of 30,000 tons of steel and almost 100,000 cubic meters of concrete were used, and more than 1 million meters of cables and 200,000 meters of pipelines were laid.

The manufacturing base covers a total area of about 200,000 square meters, equivalent to nearly 30 standard football fields, of which the first-class clean room area reaches 40,000 square meters. In such a large clean room, the number of dust particles not less than 0.5 microns per cubic foot of space is not allowed to exceed one, which is 100 times cleaner than a hospital operating room.

There is a high cost of investment in maintaining a clean environment, but not all workshops need it. Interestingly, the floor is not the hard floor we usually know. Rather, it has a mesh-like design, but is very sturdy to keep the air circulating. The air in the room should be completely changed every four minutes.

After a very strict and tedious dust removal and other links, Fan Wuxi, Ziqi and Tong Xiaoyun, accompanied by factory engineers, entered one of the dust-free workshops, where the staff must wear dust-proof clothing to avoid contamination of the wafers.

When they looked from afar, they found that the technicians in the distance were walking around with a kind of box in their arms, according to the engineer, this kind of box is generally called lot, and it contains wafers. What the technicians have to do is install the lot in a machine or a processing tool.

Due to cost considerations, only the Lot entrance is in a clean room, while the rest of the entrance is in a chase that is lower than the clean class.

Under the reminder of the engineer, Ziqi and the others deliberately paid attention to the floor of the chase workshop just mentioned, and also noticed the machine that processed those wafers, that is, the lot that was held by the technician just now.

The number of clean rooms and machines in the entire factory is very impressive, because the process of manufacturing a CPU wafer is very complex.

A Pentium 4 CPU uses 26 lithographic masking processes, each of which requires a lot of processing steps, plus mixing and metal plating, etc., and the last CPU manufacturing process has hundreds of steps.

Many workshops require the use of ultraviolet radiation, which is essential, but white light is usually used in the dust-free workshop, and the dust-free workshop that Fan Wuxian just visited uses orange light, which is different from the use of other dust-free workshops, according to the engineer. This is because this is the initial process of wafer processing, and the reason is that a certain layer of the CPU is very sensitive to white light.

The staff could not touch the wafers directly, but placed them in black square boxes called lots, each box could hold 25 wafers. This kind of lot uses aluminum material as a metal layer, and the color is black.

When the worker puts the lot into the processing machine, the machine will extract the 25 wafers one by one, and then put them back into the lot after processing.

From one clean room to another, the lot is automatically transmitted according to a predetermined trajectory. There is an automatic track on the ceiling, and that track is used to teleport lots.

Under certain conditions, the lot is delivered directly to the corresponding machine without human intervention. There is a screen on each machine, and the technician observes how well the machine is working and how far the wafers are being processed.

Here, the final product is not the CPU used by the computer user, but the wafer contains a number of chips that are sent to other assembly and test plants, where the wafers are cut, the individual chips are separated, tested, labeled, and shipped before reaching the computer user.

When she saw the wafer rod, Tong Xiaoyun asked a very strange question, "Why do you want to make it round?" And what about the ones that are not squared? When cutting, the corners of the circle are wasted, right? ”

The engineer next to him immediately explained, "Because when the silicon is purified, the raw silicon is melted and put into a huge quartz furnace, and a seed is put into the furnace so that the silicon crystal grows around the seed until a near-perfect monocrystalline silicon is formed." According to the laws of physics, the final shape of this method is a cylinder, which cannot be square, and the cylinder is sliced into a circle, and you can't do whatever shape you want. ”

Tong Xiaoyun nodded again and again after hearing this, and Fan Wuxian smiled, "Actually, I don't know much, but I'm embarrassed to ask." ”

The so-called cutting of a wafer is the cutting of a predetermined silicon wafer from a monocrystalline silicon rod by a machine and dividing it into a number of tiny areas, each of which will become the core of a CPU.

The next step is photocopying, which is to coat a photoresist substance on the silicon oxide layer obtained by heat treatment, and the ultraviolet rays irradiate the silicon substrate through a template printed with the complex circuit structure pattern of the CPU, and the photoresist substance is dissolved in the place irradiated by the ultraviolet rays.

Then there is etching, which uses a solvent to remove the photoresist irradiated by ultraviolet light, and then uses chemical treatment to etch off the silicon oxide layer that does not cover the part of the photoresist substance, and then removes all the photoresist materials to obtain a silicon substrate with grooves.

The next step is to layer and grow silicon oxides again in order to process a new layer of circuitry. A layer of polysilicon is then deposited, a photoresistive substance is coated, and the photocopying and etching processes are repeated to obtain a trench structure containing polysilicon and silicon oxides.

Then there is ion implantation, through ion bombardment, which causes the exposed silicon substrate to be locally doped, thereby changing the conductivity state of these regions and forming a gate circuit. The next step is to repeat the process over and over again. A full CPU core contains about twenty layers, with windows between the layers and metal fills to keep the circuitry connected between the layers. After the final test work, the silicon is cut into a single CPU core and packaged, and a CPU is manufactured.

Finally, there is packaging, which refers to the shell used to install the chip in the semiconductor integrated circuit, which not only plays the role of placing, fixing, sealing, protecting the chip and enhancing the thermal conductivity.

The packaging technology of the chip has gone through several generations, and the technical indicators are more advanced from generation to generation, including changing the ratio of chip area to packaging area is getting closer and closer to one, the frequency of use is getting higher and higher, the temperature resistance is getting better and better, the number of pins is increasing, the pin spacing is reduced, the weight is reduced, the reliability is greatly improved, and it is more convenient to use.

"The vast majority of CPUs today are packaged in a flip-over core. That is to say, the CPU core we usually see is actually the bottom of this silicon chip, which is flipped and packaged on the ceramic circuit substrate, which has the advantage of being able to make the CPU core directly contact with the heat dissipator. This technique is also used in the vast majority of CPUs today. The other side of the CPU core, which is covered under the ceramic circuit board, is connected to the outside circuit. The engineer told the three people, "Today's CPUs have tens of millions of transistors, and they all have to be connected to the external circuit, and the connection method is to solder a wire to the external circuit for each transistor." For example, we make CPUs with 5,000 leads, and 64-bit processors for servers with 7,500. ”

In fact, to put so many solder joints on such a small chip, these solder joints must be very small and designed with great care.

Since all the calculations are performed on very small chips. Therefore, the CPU core will emit a lot of heat, the internal temperature of the core can reach hundreds of degrees, and the surface temperature will also be tens of degrees, once the temperature is too high, it will cause the CPU to run abnormally or even burn out, so many computer books or magazines will often emphasize the importance of CPU heat dissipation.

"How much does a CPU cost?" Ziqi asked Fan Wuji.

"This question is more complicated-" Fan Wuxian also scratched his head after hearing this.

It's not that I'm afraid that I'll make everyone feel red when I say it, but because the cost of manufacturing CPUs is really complicated to calculate, and it doesn't just mean that one sentence can explain the problem.

First of all, a price factor, is the salary of the design team, this is a big investment, after all, if you want to design and manufacture CPU, you must have a very strong and highly technical design team, without this as a foundation, it is obviously impossible to do a big thing.

Generally speaking, the larger the diameter of the wafer, the more CPU cores can be divided, so that the cost of one-time manufacturing will be reduced, the profit will increase, and the more semi-finished products will be made under the same power consumption, which obviously means that the cost will decrease.

Judging from the current eight-inch wafer, a wafer can only cut more than 100 CPU cores, and if it is cut by changing the 12-inch wafer, then at least 280 pieces can be cut.

Of course, if the lithography technology is improved and the accuracy is continuously improved, the volume of the CPU core can be reduced, so that the number of units per unit area can be divided.

The price of a 12-inch wafer is about 78,000 US dollars, and according to the latest technology of Fan's Investment Group, the technology that has been successfully tested can cut more than 600 CPU cores on the 12-inch wafer, so that the cost will drop a lot, plus other expenses, it is expected that the cost of a single chip will drop to less than 300 yuan, and this is Fan's latest CPU core technology with the strongest functions.

"In fact, the profit margin of the processor is not very high, because the cost is too large. The investment in a factory is billions of dollars, plus labor taxes and operating expenses, the profit is generally about 20%, and it is possible to lose money if the operation is not good. Fan Wuxian said with some emotion.

In fact, there is another point that Fan Wuxian did not say, that is, the price of a twelve-inch wafer is seven or eight thousand dollars, which is the price of the international market, in fact, the cost of Fan's is much lower than this price, and now Fan's latest research technology is continuing to reduce the size of the CPU core, it is estimated that once successful, a twelve-inch wafer can cut out more than 2,000 pieces of CPU core, in that case, the cost drop is very powerful.

Of course, since these things have not been done, then there is no need to deliberately show off, after all, the outside world still thinks that the wafer factory of Fan's Investment Group can only process eight-inch wafers, but in fact, Fan's already has the technical reserves to manufacture a twelve-inch wafer production line, and is already under construction of the production line.

According to the latest goals of Fan's R&D team, they are already challenging the 18-inch wafer fabrication technology.

From this point of view, Fan Wuxian said that his corporate profits are not high, only 20%, but it is not a lie, because most of the current profits have been invested in technology research and development and production line construction by Fan Wuxi.

"I used to hear people say that CPUs are made of a pile of sand, and the cost is basically zero, but when I visited here today, I realized that it was such a complicated manufacturing process-" Tong Xiaoyun said with some emotion.

"I've heard that before." "The cost of a CPU is a pile of sand, and the cost of software is a CD-ROM, and if most people in this country have this idea, then it's easy to understand why the creative industries are withering." ”

Not to mention that a very nihilistic thing at Microsoft will sell for thousands of dollars, when INDOS was born, thousands of senior programmers squatted there and wrote for three years, where is this salary? What do these people eat? After it comes out, users don't buy it, who bears the risk?

In the same way, how much did people pay for turning sand into CPU? WHETHER IT IS INTEL OR AMD, THEY WILL SIGN A LIFE AND DEATH CONTRACT WITH EACH ENGINEER FOR LIFE, WHERE WILL THE MONEY COME FROM? This is not counting the costs and inputs of factory construction, equipment, sales operations, etc.

"Some people don't see the power of high-tech at all, and if everything is that simple, how can there be such a thing as the Forbes super-rich list? Although the CPU is a business built on a pile of sand, not everyone has done it. If you don't respect knowledge, you won't get ahead. Fan Wuxian shook his head and said.

"Then how do you explain the existence of Boss Coal?" Ziqi immediately asked rhetorically.

"This-uh-" Fan Wuxian was suddenly asked.

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