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With the popularity of the Internet, mobile phones have gradually become our personal standard. The key to the mobile phone lies in the chip, the quality of the chip largely determines the performance of the mobile phone, but why is the mobile phone chip so expensive?

The chip is like the brain of a mobile phone. We input the input signal into the mobile phone as a raw material. By changing the wiring and logic inside the chip, we can process the input signal in different ways.

Because of this, the mobile phone chip is a highly integrated component today. Despite the fact that it is only the size of a nail cap, it contains billions of transistors. Apple's A15 bionic chip contains 15 billion transistors, which can perform 15.8 trillion operations per second.

Therefore, we can imagine whether it is the difficulty of R & D or manufacturing.

There is often news that so-and-so has invested hundreds of millions of dollars in chips, and the archives feel that there is a lot of money, but after understanding it, it is found that so much money is only enough for the company to burn for a year. Today, we will look at how mobile phone chips are produced from two aspects of chip research and development and production. Why is it so expensive?

A chip has to go through two stages from scratch: research and development and manufacturing.

The research and development process of chip research and development can be roughly divided into:

IP (intellectual property) procurement

Front-end design

Verification

Design for testability (DFT)

Back-end design

Package design

Return test

Among them, front-end design, verification, DFT design, back-end design, packaging design and other processes require a large number of R & D personnel and the division of work and cooperation of different teams.

Some fans know which teams are here. If you are interested, you can leave a message in the comment area.

Compared with chip research and development, chip manufacturing is more difficult and has higher technical barriers.

The production and manufacture of chips can be divided into four steps: wafer manufacturing, wafer lithography development and etching, impurity doping and packaging testing.

Wafers are the material basis for chip manufacturing, refined from quartz sand and cut from 99.99% of pure silicon cylinders (also known as "silicon ingots"). Due to the different sizes of chips, dozens to thousands of chips can be split from 12-inch wafers) and polished to be extremely smooth Then thin films of conductors, insulators or semiconductors are deposited on the wafer according to the structural requirements. At present, China has a certain wafer manufacturing capacity, which can basically achieve domestic self-use.

Wafer lithography development and etching lithography technology determine how small the transistor on the chip can be. The wafer is placed in a lithography machine and exposed to deep ultraviolet light (DUV). Light is projected onto the wafer through the mask, and the optical system of the lithography machine (the lens of the DUV system) shrinks the circuit pattern designed on the mask and focuses it on the photoresist on the wafer.

Photoresist, also known as photoresist, refers to the corrosion resistant film material whose solubility changes by irradiation or radiation of ultraviolet light, electron beam, ion beam, X-ray and so on.

When the light shines on the photoresist, a chemical change occurs and the pattern on the mask is printed on the photoresist coating.

Etching is to remove the degraded photoresist to show the expected pattern.

During the etching process, the wafer is baked and developed, and the photoresist is washed off, showing a 3D pattern of an open channel.

Advanced etching technology enables chipmakers to use double, quadruple and interval-based patterns to create tiny dimensions of modern chip designs. The chip design of the cavity structure as high as 175 layers such as 3D NAND needs to ensure that the cavity depth is completely correct, and the etching process is very difficult.

The process of etching a designated position by a lithography machine is extremely precise and complicated. in fact, only the Dutch company ASML has the ability to produce expensive lithography machines, and its 7nm lithography machine sells for as much as 100 million US dollars.

Adding impurities can increase the complexity of the three-dimensional structure. The more complex the integrated circuit is, the more complex the three-dimensional structure is, and the more complex the steps of adding impurities are. The basis of integrated circuits is PN junctions. In order to form PN junctions, different impurities must be added to different wafers (in essence, P and N-type impurities are added to change their conductive properties).

PN junction: using different doping processes, P-type semiconductors and N-type semiconductors are fabricated on the same semiconductor (usually silicon or germanium) substrate by diffusion, and the space charge region is called PN junction at their interface. PN junction has unidirectional conductivity and is the material basis of many devices in electronic technology, such as semiconductor diodes and bipolar transistors.

Package testing in the process of packaging, in order to remove the chip from the wafer, it is necessary to cut it into a single chip with a diamond saw. The chip split from the wafer, also known as the "bare crystal", is then placed on the "substrate", which uses foil to direct the input and output signals of the bare crystal to other parts of the system. Then we will cover it with a lid with a "homogenizer", a small flat metal protective container filled with coolant to ensure that the chip can keep cool during operation.

After the above process, the chip manufacturer has completed the process from the layout to the chip entity, but whether the chip can work specifically and whether its electrical performance is up to the standard still need to be tested to determine. Therefore, chip manufacturers need a group of back-end testers to test the performance of the chip.

Of course, semiconductor manufacturing involves much more than these steps, and chips have to go through more steps such as measurement, plating, testing and so on. Each chip has to go through this process hundreds of times before it becomes part of electronic equipment.

Research and development costs understand the chip research and development and manufacturing process, the document will take you to continue to understand why the chip is so expensive?

The R & D cost of the chip mainly includes IP procurement, front-end design, verification, DFT design, back-end design, package design, return test and so on.

IP procurement IP procurement is a link that can not be ignored in chip research and development.

Fee models are usually divided into one-time authorization, individual product authorization, or a combination of the two.

For example, mobile phone processor chip, AI chip and so on all need to integrate CPU module. At present, most domestic chip design companies purchase ARM CPU core.

IP core, the full name of intellectual property core (intellectual property core), refers to a reusable module provided by one party in the form of logic unit and chip design.

The chip-back test includes the cost of test hardware, RA (Reliability Test) experiment, ATE (Automatic Test Equipment) machine use and R & D manpower investment.

Other front-end design, verification, DFT design, back-end design, packaging design expenditure is mainly based on the human input of R & D personnel, in addition, it also includes the usage fee of EDA software, the hardware cost of FPGA and Zebu verification platform.

Production cost chip production cost mainly includes wafer, wafer, CP (Chip Probe, wafer) testing, packaging, FT (Final Test, final test), SLT (System Level Test, system level test) and so on, most of which are concentrated in wafers and wafers.

The cost of taping refers to the manufacture of chips through a series of technological steps like an assembly line. in the field of integrated circuit design, "taping" refers to "trial production".

One-time fee is calculated according to the number of layers of the mask.

After the chip design is completed, complex graphics files will be produced, generally speaking, there will be dozens to hundreds of layers. These graphics files need to be masked in the mask factory.

The higher the process node, the more expensive the taping, because the high process requires more masks. In the 16 nm process, it takes about 60 copies, while the 7nm may need hundreds.

At present, the cheapest ASIC streaming costs tens of thousands of times. The streaming cost of 180nm is about 500000 yuan, and that of 55nm is about 2 million yuan. But the cost of 16nm has soared to 30 million-50 million yuan, and the lowest cost of 7nm is more than 100 million yuan. However, when it comes to the stage of mass production, especially when the product shipments are relatively large, when the cost of one-time taping is evenly distributed to hundreds of thousands of chips, the relative cost is much lower.

The wafer cost is calculated according to the number of pieces shipped.

Wafer prices are also distinguished according to process nodes. The cost of TSMC 12-inch wafer 40nm is about $1500 to 2000, the cost of 16nm is about $4,000 to $5000, the cost of 7nm is about $9300, the contract manufacturing price of 5nm is about $17000, and the price of 3nm is expected to reach about $30000.

Having said so much, I finally understand why the chip is so expensive!

However, Mr. documentation believes that this is not only a challenge, but also an opportunity. In 2023, with the increasing demand for smartphones, the mobile phone chip industry will have a better prospect.

This article comes from the official account of Wechat: ZTE documents (ID:ztedoc)

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