1 Overview
The electronics industry is the core of the current high-tech industry. It has played a huge role in the development of human science and technology. The electronics industry has become the fastest-growing high-tech industry in the world today and plays a pivotal role in the national economies of countries all over the world. Today's electronic technology is inseparable from the integrated circuit, which is the cornerstone of the electronic industry, and the integrated circuit is one of the greatest inventions of the 20th century .
An integrated circuit is a tiny electronic device or component. It uses a certain process to interconnect the components and wiring required in a circuit, and makes them on a small substrate, and then encapsulates them in a tube, in which all the components have been structurally integrated. Integrated circuits include semiconductor integrated circuits and hybrid integrated circuits .
Semiconductor integrated circuits use semiconductor technology to manufacture resistors, capacitors, inductors, transistors and other components and wiring in the circuit on the same semiconductor material to form a complete circuit system with independent functions.
Hybrid integrated circuit is to solidify multiple different semiconductor integrated circuits and discrete electronic components on the same substrate (ceramic material or semiconductor material) through microfabrication technology, and integrate them into a complete, A circuit system with independent functions.
This article mainly introduces the knowledge and technology related to semiconductor integrated circuits .
Classification of semiconductor integrated circuits
Integrated circuits can be divided into digital integrated circuits, analog integrated circuits and mixed signal integrated circuits according to their functions .
Digital integrated circuits refer to a type of circuit that only processes digital signals, also known as logic circuits . Such products mainly include processing microprocessor (MPU), microcontroller (MCU), memory (RAM, ROM), interface circuit, etc. Digital integrated circuits are usually composed of basic logic gate circuit units.
**Analog integrated circuit refers to a type of circuit that completes functions such as amplification, conversion, modulation, and calculation of analog signals. **Because this type of circuit was mainly used for signal linear processing in the early days, it is also called a linear circuit. Analog integrated circuits include amplifiers, analog multipliers, analog switches, and power circuits.
Mixed-signal integrated circuits are circuits that can process both digital and analog signals . Mixed-signal integrated circuits mainly include: A/D converter (analog-to-digital converter), D/A converter (digital-to-analog converter).
2. Development of integrated circuits
Why was the integrated circuit invented?
What can it bring us? Through the history of the development of semiconductor integrated circuits, we will unravel the driving force behind the invention of
semiconductor integrated circuits .
driving force
In 1946, ENIAC (Electronic Numerical Integrator And Computer) was born in the United States. ENIAC is the second electronic computer after ABC (Atanasoff-Berry Computer), and it is used by the US Department of Defense to To calculate ballistics, ENIAC can perform 5000 calculations per second. ENIAC is a behemoth! ENIAC has a total length of about 30 meters, a height of about 4 meters, a thickness of about 0.9 meters, an area of about 167 square meters, and a weight of 30 tons ! The internal circuit of ENIAC uses about 18,000 electron tubes, 7,200 resistors, 10,000 capacitors, 500,000 lines, and a power of about 150 kilowatts.
Electronic computers provide unparalleled computing power , but this kind of computer has several outstanding problems: large size and high power consumption . If the electronic components and wiring inside the computer can be integrated on a small carrier , this will solve the problem of size and power consumption! This is the internal driving force for the birth and development of semiconductor integrated circuits !
develop
On December 23, 1947, William Shockley (William Shockley) and John Bardeen (John Bardeen) of Bell Laboratories in the United States invented the touch-type triode, which is the world's first crystal triode , which marks the electronic technology The first step has been taken from the tube era to the transistor era!
Before that, computer circuits could only use electronic tubes with large volume, high power consumption, and unstable structure. Transistors have the main functions of electronic tubes, and at the same time solve the problems of large volume, high power consumption, and unstable structure . After the invention of the transistor, Shockley published "The Theory of PN Junctions and PN Junction Transistors in Semiconductors" in an internal publication of Bell Laboratories in 1948. In November 1950, Shockley published "Electrons and Holes in Semiconductors", laying the foundation The basic theory of PN junction and surface junction transistor is explained .
In 1954 , Texas Instruments purchased the patent for the production of electronic transistors from Western Electronics for $25,000, and developed the first commercial silicon transistor Type 905 in the same year. Texas Instruments became the only company that mass-produced silicon tubes at that time.
In 1958 , Kilby of Texas Instruments had a whim: a very small microcircuit composed of many devices can be fabricated on a single chip. On September 12, 1958, Kilby turned this idea into reality and developed the world's first integrated circuit (this circuit is actually an integrated circuit containing only 12 components) , and with this invention, Kilby received the Nobel Prize in Physics in 2000.
In 1959 , Bob Noyce, who was working at Fairchild at the time (later Fairchild Semiconductor, the founder of Intel), created the mask exposure etching method to produce integrated circuits .
In 1964 , Jean Amdahl, who was only 40 years old, served as the chief designer of IBM. The IBM360 computer, which took four years to develop, came out. IBM360 is the world's first integrated circuit computer built with integrated circuits, also known as for third-generation computers. This computer has 6 models of large, medium and small, covering the applications of scientific computing and transaction processing, and can be used in 360 degrees, so it is named IBM360. Compared with the previous computers, the biggest feature of this computer is that it has shifted from military use to civilian use. It represents the all-round application of computers from the industrial and commercial circles to the scientific circles .
In 1970 , Intel's scientist Ted Hoff presided over the design of the world's first microprocessor - Intel 4004 . Intel 4004 integrates 2250 transistors on-chip, the distance between transistors is 10 microns, it can process 4-bit data, 60,000 operations per second, and supports 8-bit instruction set and 12-bit address set.
In June 1978 , Intel launched the 8086 microprocessor. The 8086 is the originator of the x86 architecture microprocessor , and various subsequent microprocessors are compatible with it. The main frequency of 8086 is 4.77MHz, using 16-bit registers and 16-bit data bus. 8086 microprocessor uses +5V power supply, 40-pin dual-in-line package, 16 data lines and 20 address lines, implements segmented management of memory space, realizes addressing of 1MB space, and adopts parallel pipeline Way of working. 8086 is an epoch-making microprocessor.
In 1993 , Intel released the Pentium series microprocessor 80586, Pentium series microprocessors are fully compatible with previous Intel processors. It is worth mentioning that there are two data pipelines in the Pentium processor, which can execute two instructions at the same time. Intel Corporation calls this ability to execute two instructions at the same time superscalar technology. The first-generation Pentium processors are clocked at 60MHz and 66MHz.
On August 31, 2018 , Huawei released the Kirin 980 chip at the IFA exhibition in Berlin, Germany . The Kirin 980 chip is an ARM-based 64-bit system chip launched by Huawei Hisilicon. It is the world's first commercial mobile phone SoC chipset (4 A76+4 A55 eight-core chip) manufactured by TSMC's 7nm process. The highest main frequency up to 2.8GHz. Kirin 980 integrates eight CPU cores, ten GPU cores, dual ISP, i8 sensor processor, security engine, and supports UFS 2.Hi-Fi audio, 4K video.
Throughout the development of semiconductor integrated circuits, two development trends can be summarized:
1. The volume is getting smaller and smaller.
2. The functions are more and more complex.
3. Integrated circuit materials
3.1 Semiconductor materials
Semiconductor materials are the main materials for manufacturing semiconductor integrated circuits . At present, there are two types of semiconductor materials used in integrated circuits: elemental semiconductors and compound semiconductors . Elemental semiconductors mainly include germanium (Ge) and silicon (Si). Compound semiconductor materials include silicon carbide (SiC), gallium arsenide (GaAs), indium gallium arsenide (InGaAs), and the like.
3.2 Properties of semiconductor materials
Semiconductor integrated circuits are mainly manufactured using semiconductor materials. The reason why semiconductor materials can be used to manufacture extremely complex semiconductor integrated circuits is because semiconductors have a series of characteristics: electrical conductivity, doping characteristics, temperature characteristics, photoelectric characteristics, pressure characteristics, etc.
Conductive properties
The strength of a substance's ability to conduct electricity is expressed by its conductivity, and the reciprocal of the conductivity is called resistivity. According to the size of resistivity, substances in nature can be divided into three categories: conductors, semiconductors and insulators . The resistivity of semiconductors is between conductors and insulators, as shown in the figure below:
Doping characteristics
Adding trace amounts of other elements into semiconductor materials, called doping impurities (referred to as doping) , can change the conductivity of semiconductors in a wide range. Taking the semiconductor material silicon as an example, the resistivity of pure silicon at room temperature is 230000Ω*cm, but as long as 0.000001% (one millionth) of phosphorus is added, the conductivity of the silicon material containing impurities will increase by 200000000%. (200,000 times)! It can be seen that although the content of doping elements is extremely small, it plays a decisive role in the conductivity of semiconductors .
temperature characteristics
Semiconductors have an important characteristic. As the temperature rises, the carrier concentration in the semiconductor increases and the resistance decreases . This effect of semiconductors can be used to make semiconductor thermistors. With the continuous development of semiconductor integrated circuit technology, semiconductor integrated temperature sensors have attracted more and more attention. The semiconductor integrated temperature sensor has the advantages of smaller size and easy system integration . The integrated temperature sensor integrates a temperature sensing device, an adc circuit, and a digital circuit, and they can output digital signals, which can be conveniently processed in a microprocessor. The semiconductor integrated temperature sensor mainly uses bjt as the temperature measurement device. The following figure is the functional block diagram of the semiconductor temperature sensor LM35:
Photoelectric properties
The conductivity of semiconductor materials can be increased hundreds of times when exposed to light , and this effect of semiconductors can be used to make semiconductor photosensors: photodiodes (Photo-Diode) . A photodiode is a semiconductor device composed of a PN junction with unidirectional conductivity. The photodiode works under the action of reverse voltage, and the current generated under the light of general illuminance is called photocurrent. If a load is connected to the external circuit, an electrical signal is obtained on the load, and this electrical signal changes correspondingly with the change of light. The photoelectric sensor is as follows:
pressure characteristics
When the semiconductor is subjected to stress, the resistivity changes due to the change of the energy band caused by the stress. This physical phenomenon is called piezoresistive effect . The semiconductor pressure sensor can be made by using this effect of the semiconductor. The structure of this pressure sensor is simple and reliable, and there are no relative moving parts. The elastic element and the pressure sensitive element in the sensor are integrated to improve the performance of the sensor. The following figure is the functional block diagram of the semiconductor pressure sensor LPS22HH:
3.3 This certificate semiconductor and impurity semiconductor
Intrinsic semiconductor
A pure semiconductor material without any impurities and defects is called an intrinsic semiconductor , and the conductive characteristics of this semiconductor depend on the inherent characteristics of the material itself.
Impurity semiconductor
The semiconductor material used in the integrated circuit is not the original semiconductor , but the impurity semiconductor. A certain amount of other elements are doped into the semiconductor of this certificate. This kind of semiconductor doped with impurities is called impurity semiconductor. The doped impurities are called impurity atoms, and the process of doping impurity atoms is called doping . After doping impurities in a pure semiconductor material, the conductivity of the semiconductor will change greatly.
N-type semiconductor
After doping trace trivalent elements phosphorus (P), arsenic (Sb), antimony (As) and other elements into the semiconductor material, a lot of negatively charged electrons will be generated in the semiconductor material, so that the concentration of free electrons in the semiconductor is much higher than that of hole concentration. Such impurities provide negatively charged (Negative) electron carriers, so they are called N-type impurities, and this kind of semiconductor is called N-type semiconductor . For N-type semiconductor materials, the total positive charge is equal to the number of negative charges, and the material as a whole is electrically neutral.
P-type semiconductor The
semiconductor material is doped with trace trivalent elements boron (B), aluminum (Ga), and indium (In), so that the concentration of holes in the semiconductor is much higher than the concentration of free electrons. Such impurities provide positively charged (Positive) hole carriers, so they are called P-type impurities, and this kind of semiconductor is called P-type semiconductor . For P-type semiconductor materials, the total positive charge is equal to the number of negative charges, and the material as a whole is electrically neutral.
