We talk about chips every day, do you know what a chip really is?
By Shirong Liu
We talk about chips every day, do you know what a chip really is?
1. The invention of the chip changed the way of human life
December 23, 1947, the United States Bell Labs 3 scientists John Baden, William Shockley and Walter Bratton invented the germanium crystalline transistor, the electronic world into the semiconductor era. The three inventors of the crystal triode won the 1956 Nobel Prize in Physics.
The 1950s was the golden age of semiconductors, and almost all semiconductor materials and basic processes were developed during this period.
On October 18, 1954, Texas Instruments invented the transistor radio, a radio with four crystal triodes small enough to fit in a pocket.
On September 12, 1958, Jack Kilby (1923-2005), an electronics engineer at Texas Instruments, invented the integrated circuit and, in 1959, successfully manufactured the world's first integrated circuit, the chip. The integrated circuit was a PNP-type transistor (triode), resistor and capacitor etched on a piece of germanium, which was connected into a circuit with external wires. This simple integrated circuit opened the prelude to the chip industry, but also the level of human science and technology to a new peak, and completely changed the way of life of mankind.
The continuous progress of chip manufacturing technology allows the price of a single transistor to fall. 1959, a chip with six transistors, equivalent to $ 10 per transistor; 1971, a chip with 2,000 transistors, equivalent to $ 0.3 per transistor; 2004, a chip with tens of billions of transistors, the price of a single transistor fell to one billion dollars. Chip cost-effective improvement, so that the chip into the ordinary people's families become possible.
The chip is arguably the greatest invention of the 20th century, and many other inventions have been built on it. Today, we live in a world surrounded by chips, and it's hard to get around without them.
People's daily lives are inseparable from the chip, cell phones, computers, smart watches and other smart devices have a chip, optical cats, routers, USB flash drives, memory cards, mobile hard drives and other network equipment and computer peripherals have a chip, ID cards, passports, bank cards, shopping cards, consumer cards and other accompanying documents have a chip, TV, stereo, projectors, chargers, LED lights, electronic scales, air conditioning, refrigerators, microwave ovens, Induction cooker, water heater and other household appliances also have chips, access control, monitoring, solar batteries, etc. also need chips. If anyone invents a code to disable all the chips in the world, human life will come to a standstill.
Jack Kilby won the 2000 Nobel Prize in Physics for inventing the chip. He is also the inventor of the handheld calculator and the thermal printer. When Kilby was called a scientist, he modestly said, "Scientists are people who explain things, to have a great idea; and I am a problem solver, that is, an engineer, the duty is to invent new processes, manufacturing new products, and also to make money from the invention."
2. Recognize the chip must first understand the "PN junction"
From the above, we can see, in the semiconductor material to make diodes, transistors, resistors, capacitors and other electronic components, and then connect them with wires, which is the integrated circuit, also known as the chip. Chip. To recognize the chip, you must first understand the "PN junction", which is the core of semiconductor technology.
Semiconductor materials doped with pentavalent elements, electron concentration increases, the formation of N-type semiconductors; semiconductor materials doped with trivalent elements, hole concentration increases, the formation of P-type semiconductors. The term "hole" refers to the empty space left on the *** valence bond after the electron gains energy and gets rid of the *** valence bond to become a free electron.
P-type semiconductors and N-type semiconductors in close contact with the negatively charged electrons and positively charged holes will be diffused to the other side; electrons and holes in the diffusion of the contact surface resulting in the formation of an internal electric field, the internal electric field prevents this diffusion, so that the electrons and holes to drift back. When the diffusion rate of electrons and holes and drift speed to reach dynamic equilibrium, P-type semiconductor and N-type semiconductor contact surface will form a "PN junction".
"PN junction" is the main property of "unidirectional conductivity". If the P-type semiconductor end as a positive, N-type semiconductor end as a negative, the current can pass through the PN junction; if the N-type semiconductor end as a positive, P-type semiconductor end as a negative, the current can not pass through the PN junction. Computer binary is determined by the performance of the "PN junction", the current through the "PN junction" on behalf of the "1", the current can not pass the "PN junction" on behalf of the "1", the current can not pass the "PN junction" on behalf of the "1". The "PN junction" represents "0".
The "PN junction" is the diode. If you let two P-type semiconductor sandwiched between a N-type semiconductor, it constitutes a triode, which is the PNP-type triode mentioned above. Of course, if you let two N-type semiconductors in the middle of a P-type semiconductor, this is a NPN-type triode.
Ordinary people can not see the chip "real body", the chip is as small as human dandruff, large as human fingernail cover, because it is too thin, must be encapsulated in a sealed shell in order to connect to the external circuit. Open the computer, TV and other electrical appliances, you can see a very large circuit board, the circuit board has a lot of electronic components, those who have more than one pin of the electronic components is the chip, these pins are connected to the chip's inputs and outputs, some on both sides of the chip encapsulation, some in the four faces, some are at the bottom of the matrix arrangement, dense, there are more than 1,000 pins.
3. Making a chip is like carving the earth and all the roads and buildings on a grain of rice
Here we need to mention a concept, that is, "Moore's Law". 1965, the world's leading chip maker, the United States of America, one of the co-founders of Intel Corporation, Gordon Moore proposed that a single chip on a single chip, and the chip is not a single chip, it is a single chip. In 1965, Gordon Moore, one of the founders of the world's leading chip maker Intel, suggested that the number of transistors on a single chip would double every year. Later he corrected it to double every two years. This judgment has been proved to be basically correct, and in 2011, there were 2.27 billion transistors on Intel's Core i7 chip. Currently, the number of transistors on some high-end chips exceeds tens of billions. A few years ago, the AI chip WSE, produced by semiconductor manufacturer Cerebras Systems using TSMC's 16-nanometer process, on the other hand, integrated 1.2 trillion transistors!
"Process" refers to the gate width of the transistors on a chip, which can be loosely understood as the size of the transistors. The smaller the process, the more transistors you can make on a chip, and the larger the integrated circuit.
Chip computing speed is increasing, thanks to the chip's increasing integration. The higher the integration of the chip, the smaller the electronic components on it, the shorter the wires between the electronic components, the shorter the time taken for the current to pass through, the lower the energy consumption, and the faster the processing speed.
To make a chip carry more transistors, there are three ways to do it: increase the chip area, reduce the transistor size, and make the integrated circuit three-dimensional. Increasing the chip area is generally not considered, because it will increase energy consumption and reduce the efficiency of the chip. Nowadays, people mainly take the latter two methods to increase the number of transistors on the chip.
Chip fabrication belongs to the microscopic world, where the electronics on it are as small as a few atoms or a few molecules large, to be measured in smaller units of measure, nanometers and angstroms. The smallest scale on a typical ruler is millimeters, with 1 millimeter equaling 1,000 micrometers, 1 micrometer equaling 1,000 nanometers, and 1 nanometer equaling 10 angstroms. The diameter of a human hair is 70,000 nanometers and its circumference is 220,000 nanometers. Making a chip with a process 5 nm process is like building 44,000 highways along a hair.
There is a limit to how much you can reduce the size of an electronic component, so people think about building multiple layers of integrated circuits on a single chip to increase the number of transistors. This is like building residential housing, bungalows to accommodate the number of residents is small, built into dozens of high-rise buildings to accommodate the number of residents is more. The stacking of integrated circuits is much more complex than building a building. The layout of each layer of the building is the same, and the circuitry of each layer of the chip is different, and the connection between the layers is exceptionally complex.
Let's take the analogy a step further, making a chip is like carving out a complete planet on a grain of rice, and also carving out all the roads and buildings on the planet. The roads are the wires on the chip, and the buildings are the electronic components on the chip. Through this analogy, the reader can imagine how complex and difficult it is to make a chip.
4. The purification of silicon is the foundation of the chip industry
There are many semiconductor materials, but in practice, more than ninety percent of the choice of silicon, because the melting point of silicon is 1,415 degrees Celsius, which allows high-temperature processes in chip processing.
Silicon is smelted from sand, but to smelt sand into silicon that can make chips requires extremely high purity. We call the purity of 99.99% pure gold (4 9), but the purity of silicon to manufacture chips should be at least 11 9, that is, every 1 billion silicon atoms in the impurity atoms shall not be more than 1, this purity of silicon in 1955, the United States, Bell Labs refined. At present, a chip with hundreds of billions of electronic components, the purity of silicon requirements are higher, at least 13 9, which is the basis of chip manufacturing, do not master the purification of silicon technology, it is impossible to make a chip!
Readers will ask, why is the purity of silicon required for chip manufacturing so high? The electronic components on the chip are very tiny, if the chip is manufactured with a 5-nanometer process, there are 1 nanometer impurities on it will scrap the whole chip. We may wish to draw an analogy. If a highway is 40 meters wide, and there is a 1-meter-wide boulder in the middle of the highway, cars can avoid the stone and not cause traffic congestion. However, if a highway is only 5 meters wide, there is a 1-meter-wide boulder in the middle of the highway, the car can not avoid the stone, the highway will be blocked.
Therefore, the manufacture of chips not only requires high purity of silicon, but also requires that all aspects of the manufacturing process is dust-free, the purity of which is 100,000 times that of a hospital surgical suite, and even half of the process is carried out in a vacuum environment. Because of this, the new crown of the pneumonia epidemic chip manufacturing plant without the need to stop work to fight the epidemic, because the staff from head to toe full body protection, some of the protective clothing and even comes with a respiratory system, in order to prevent the human metabolism of the shedding of material and exhaled gas contamination of the chip.
5. Photolithography is actually an integrated circuit projector
The name "photolithography" is an inaccurate and misleading translation, and many people mistakenly believe that photolithography is the process of physically touching the surface of crystalline silicon to "engrave" an integrated circuit. The name "photolithography" is inaccurately translated and is very misleading. In fact, the chip is not "carved" out, but "shine" out. Therefore, photolithography called "integrated circuit projector" is more appropriate.
When the manufacturing chip wafer into the photolithography process stage, the photolithography machine through the mask version of the integrated circuit map projected onto the wafer surface photoresist, photoresist exposure, through the chemical solution to the exposure area etched, and then cleaned, so that the integrated circuit of the graphic is out. The photolithography process and the traditional photographic photo printing is a reason, the light through the negative so that the photographic paper sensitized, and then the sensitized photographic paper in the liquid developer, fixing.
A chip has to go through dozens or even hundreds of photolithography, and a number of processes after photolithography will take a few more weeks before it can enter the packaging stage.
Chip manufacturing technology is changing rapidly, but most of the core technology for chip manufacturing comes from Bell Labs, whose contributions to the information technology revolution will live on in history.
7. Can you make a chip with a photolithography machine?
Many readers are interested in lithography, and think that with lithography, you can make chips. In fact, although lithography plays an important role in chip manufacturing, it is only one of more than 1,000 processes in chip manufacturing, with lithography, but if you can't master the other processes, you can't make a chip.
In 1961, the U.S. GCA company manufactured the world's first lithography. Currently, there are seven companies in four countries in the world that can manufacture photolithography, namely, Asmael in the Netherlands, Intel, Ultra Tech Semiconductors, and Rudolph in the United States, Nikon and Canon in Japan, and Sensei Microsystems in Germany.
As mentioned above, the chip industry is based on materials, that is, the purification of silicon, do not master the purification of silicon technology, the production of chip-level purity of crystalline silicon, chip-making can not be discussed.
Then, there are hundreds of billions of electronic components on the chip, so huge circuitry by hand is not drawn, you must use electronic design automation software EDA. EDA is a comprehensive use of many natural disciplines, by the United States Kadant, Synopsys and the three companies monopolized by the Mingguang.
EDA plays a decisive role in the chip manufacturing process, the function of the chip and the degree of integration, depends entirely on the design capabilities of EDA. With high-purity silicon and photolithography, but no EDA or will not use EDA, as usual, can not make a chip.