Integrated Circuits Introduction
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5/26/2020 Integrated Circuits Semiconductor elements Introduction Integrated circuits (ICs) are microelectronic elements. They are characterized by miniature size and weight, low power requirements and low cost, while having increased reliability and significant complexity. The production technology allows them to build a whole system in a single integrated circuit (chip), which contains tens of millions of transistors. 1 5/26/2020 Applications Modern electronics began with the discovery of the transistor in 1947 and the subsequent development of integrated circuits (ICs) in the early 1960s. Thanks to ICs, modern computers, information technology, telecommunications, space and aircraft equipment, entertainment, automotive and medical electronics, navigation systems, audio and video devices and much more have become possible. Goals and prerequisites Basic concepts and classification of integrated circuits, key processes in their production and the structure of the elements are considered. After studying the material you should: Познавате What is an integrated circuit Types of integrated circuits Разбирате Planar technology The main processes in the production of silicon IC The structure of the elements implemented in the IC Анализирате The need for insulation between the elements Problems in integrating passive components Оценявате Advantages and disadvantages of bipolar, MOS and CMOS ICs Prerequisites: semiconductors, bipolar and MOS transistors 2 5/26/2020 What is an integrated circuit? An integrated circuit (also called a chip or microchip) is defined as a combination of inextricably linked elements implemented on or in a common substrate. Many transistors, diodes, resistors and capacitors are manufactured as a whole and are enclosed in a common case. The whole scheme is considered as one indivisible component. Integrated circuits classification According to the technology for their production, the following IC types differ: Types of integrated circuits Monolithic Layered ICs Hybrid MOS Bipolar Thin-film ICs Thick-film ICs NMOS PMOS CMOS Mixed 3 5/26/2020 Monolithic integrated circuits IC Semiconductor Needle substrate In monolithic integrated circuits, all elements are made inside of a common semiconductor substrate. They can be bipolar or MOS ICs according to the transistors available in them. There are also mixed monolithic ICs that contain both types of transistors. Although they contain millions of transistors, these integrated circuits are several millimeters in size. Layered Integrated Circuits Capacitor Al SiO2 NiCr Dielectric substrate Resistor Layered ICs are made of conductive or non-conductive material, which is applied on an insulating substrate. According to the layer thickness, they are divided into thin- layer and thick-layer ICs. They are used to make only passive elements - resistors and capacitors. 4 5/26/2020 Hybrid Integrated circuits Resistor Case of layered IC Dielectric substrate IC Бобина Capacitor Hybrid ICs combine layered passive elements with integrated circuits and other discrete components mounted on the insulation pad. Linear and Digital ICs According to their purpose, integrated circuits are classified as digital and linear. Linear ICs are used in analog circuits - audio amplifiers, voltage regulators, operational amplifiers and more. In them the signal is continuous in time. In digital circuits, IC signals have two levels. They are used in computers, computer networks, digital clock calculators and others. 5 5/26/2020 History of Iс development First Ge transistor with point contact Bell Labs, 1947 John Bardeen, Walter First Si transistor – Гордън Тийл, Texas Brattain, William Shockley, Instruments, 1954 Winners of the 1956 Nobel Prize in physics First MOSFET Bell Labs, 1959 Dawon Kahng, Mohamed M. Atalla Revolution in microelectronics First hybrid Ge IC, 1958 1 transistor and 4 other elements on 1 chip Jack Kilby Winner of the 2000 Nobel Prize Texas Instruments, 1958 6 5/26/2020 Planar process –1959 A more efficient method of manufacturing transistors Fairchild Electronics – Jean Hoerni and Robert Noyce First commercial monolithic Si IC, implemented with planar process Fairchild, 1959 One Binary Digital (Bit) Memory Device on a Chip, 4 Transistors and 5 Resistors Start of Small Scale Integration (SSI) technology Robert Noyce First Linear IC mA 709 OPAMP, 1965 mA 702 OPAMP, 1964 Operational amplifier Robert Widlar, Fairchild, 7 5/26/2020 First Semiconductor memories Intel Corporation DRAM, 1970 Fairchild 4100 SRAM, 1970 First 1,024 Bit Memory Chip – 1970 First 256-Bit Static RAM – 1970 Intel 1702, EPROM, 1971 First EPROM Memory chip Birth of microprocessor – 1971 The first computer on a single chip – 2300 transistors,1MHz, MOS technology Intel 4004, 4-bit microprocessor, 1971 Federico Faddin 8 5/26/2020 Minicomputer revolution 2901 Bit-Slice Microprocessor, 1975 Motorola 68000, 16-bit microprocessor Advanced Micro Devices, 1975 Beginning of the Medium Scale Integration Motorola, 1979 (MSI) technology Beginning of the Large Scale Integration (LSI) technology Minicomputer revolution HP Focus Chip, 32-bit proc, 1981 Intel Pentium 4, 64-bit proc, 2000 Hewlett-Packard Co. 450,000 transistors Intel Corporation Beginning of Very Large Scale Integration (VLSI) technology 9 5/26/2020 Moor Law Gordon Moor, Intel According to the number of transistors in integrated circuits, they are classified as those with small, medium, large and very-large degree of integration. According to Moore's Law, the number of transistors in the IC doubles in approximately 2 years (1.96). This law is illustrated by the evolution of Intel's microprocessors. 10 5/26/2020 Manufacturing of monolithic ICs Monolithic ICs are built in layers on a silicon wafer and in a single technological process hundreds of ICs are produced simultaneously. All operations are performed in "clean rooms", where a low level of dust and impurities is maintained, which would damage the entire chip. Planar process Structure of the surface Layers he structure of IC is complex. It consists of many layers that are created sequentially in a certain plane in the so-called planar process. The planar process will be illustrated by the production of one MOS transistor, despite the fact that millions of transistors are produced simultaneously. 11 5/26/2020 Oxidation SiO2 Substrate Initially, a p-silicon substrate is covered with SiO2 by oxidizing at high temperature in pure oxygen medium. The resulting insulation layer protects the surface in subsequent operations. Photolithography UV light Mask Photoresist SiO2 Images on SiO2 are created by an operation called photolithography. A photosensitive layer – photoresist – is applied on the surface. A corresponding mask is used for each image. When irradiated with UV, the unprotected area of the photoresist is polarized, which changes its solubility. 12 5/26/2020 Etching Window Window SiO2 The exposed (soluble) photoresist is removed with hydrofluoric acid. The operation is called etching. This opens a window to the silicon substrate in a shape determined by the mask. Subsequently, the remaining photoresist is removed. Gate formation Polysilicon Polysilicon UV light gate Mask A sequence of the same operations is used to form the next layer - oxidation, coating the oxidized surface with polysilicon, applying a photoresist, a second mask to form an image, irradiation with UV light and etching. As a result, two silicon windows are created. The remaining polysilicon serves as the gate of the transistor. 13 5/26/2020 Ion implantation Сорс Дрейн Introduction of impurities in the windows open to silicon is performed with the doping operation. In this case, phosphorus or boron atoms are introduced into the substrate to create regions with N- or P-conductivity, respectively. The impurity atoms are ionized, accelerated and by bombarding the surface are implanted in it. This creates the drain and source areas. Contacts Contact holes The same operations are used to form contact holes - oxidation of the entire surface, photolithography with a mask for the holes to the areas of the source, gate and drain and etching to remove the photoresist. 14 5/26/2020 Metallization Metal pads Metal (aluminum) atoms are deposited on the entire surface, filling the contact holes. Photolithography with an appropriate mask is then used and, after etching, metal pads are formed to connect electrical conductors. The operation is called metallization. Testing During production, precise control of all operations is performed. The plates are tested with computer-controlled equipment in clean rooms, where staff have suits similar to those of astronauts. 15 5/26/2020 Assembling Gold wires Contact pads Wafer cutting Base for mounting Transistors and integrated circuits are manufactured together with hundreds of neighbors on a single wafer. After testing the wafer, it is cut with diamond cutters and each IC is mounted in a metal, plastic or ceramic case. The chip is connected to the case with gold wires, which are pressed under pressure to the contact pads (the operation is called bonding). Cases Types Cases are essential for the effective isolation of IC from the environment and to facilitate its use and installation in electronic systems. Some of the most commonly used cases are shown in the figure. 16 5/26/2020 Bipolar Integrated Circuits Diffusion furnace Silicon wafers Bipolar ICs contain bipolar transistors and other passive components. They are produced in a common technological process, which covers a sequence of a larger number of operations