FABRICATION OF INTEGRATED CIRCUITS

Integrated FETs

Integrated FETs In general the Integrated FETs (field effect transistors) are of two types namely Junction field effect transistor (JFET) Metal oxide semiconductor field effect transistor (MOSFET) 1 Integrated JFET The basic processes used for the fabrication of JFET are exactly similar to those used in the fabrication of BJT. The JFETs are further classified […]

Integrated Capacitors

Integrated Capacitors: Integrated Capacitors – The common parallel plate capacitor structures are as shown in the Fig. 1.24. In most widely used type shown in Fig. 1.24 (a), the two polysilicon plates are seperated by silicon dioxide (Si02). Here the lower plate rests on the top of the substrate. The capacitor shown in Fig. 1.24 […]

Integrated Resistors

Integrated Resistors: In Integrated Resistors circuit design, the importance is given to the maximum usage of transistors. For example digital CMOS, nMOS and GaAs circuits are fabricated entirely with transistors and diodes. The resistors are grouped into two groups ; one formed within monolithic IC and other composed of film resistors. The monolithic IC resistors […]

Monolithic Diodes

Monolithic Diodes: Monolithic Diodes – The fabrication of diode is very straight forward. Generally any two terminals of the transistor are connected together to form one of the electrodes while the remaining terminal can be considered as remainining electrode of a diode. The different connections in transistor to utilize it as a diode are as […]

PNP Transistor

PNP Transistor: There are different ways of fabricating PNP Transistor in integrated circuits. The important means of integrating PNP Transistor are (i) vertical p-n-p, (ii) lateral p-n-p and (iii) triple diffused p-n-p. In vertical p–n–p transistor, the p type substrate is used as p-type collector while the n-epitaxial layer is used as base. Obviously the […]

Monolithic Transistors

Monolithic Transistors: The cross-sectional view of an integrated monolithic transistors and discrete planar transistor are as shown in the Fig. 1.17 (a) and (b) respectively. The main difference between monolithic integrated transistor and discrete planar transistor is that collector contact in monolithic integrated transistor is at top, while in the discrete planar transistor it is […]

Metallization

Metallization: Metallization is a process in which a thin layer of metal is formed which is used to make interconnections between the components on the chip as well as interconnections between the components and the outside world. In general metallization applications are divided into three groups, (i) gate, (ii) contact and (iii) interconnects. In VLSI, […]

Ion Implantation

Ion Implantation: As we know, the conductivity of the semiconductor increases when small impurity is added to it. The process of adding impurity is called doping while the impurity to be added is called dopant. So ion implantation is a process of adding dopant to the silicon substrate. The ion implantation process is controllable, reproducible […]

Diffusion

Diffusion Diffusion is the Oldest Technique used to add impurity into the Substrate. The main aim of thee Diffusion process is to change ┬áthe Conductivity of silicon substrate over a depth. The diffusion is used in bipolar device technology to form bases, emitters, collectors ; while in MOS device technology to form source and drain […]

Reactive Plasma Etching

Reactive Plasma Etching: The reactive plasma is the discharge in which gases ionized producing chemically active species, oxidizers, reagents. The plasma is reactive in both gaseous and solid phase, hence the name is reactive plasma. These plasmas are used to remove the ‘materials from the surfaces which are not masked by the lithographic patterns. The […]

Lithography

Lithography: Lithography is a process which is used to produce a multiple image on the resists which covers the wafer. A lithographic process can be realized with the help of three subprocesses given by, deposit of the resist, imaging of the wafer, and etching of the oxide. In lithographic process, the radiation from a source […]

Oxidation

Oxidation: Oxidation is very important process in the IC fabrication. In one line, oxidation can be explained as the production of Si02 using the thermal growth technique. Some of the important uses of Si02 are as follows. In bipolar and MOS transistors, it isolates one device from other. It provides surface passivation. It acts as […]

Molecular Beam Epitaxy

Molecular Beam Epitaxy: The molecular beam epitaxy (MBE) is based on evaporation. In MBE, the film is evaporated and deposited one layer at a time. In the process, no chemical reactions are considered. Instead of that the evaporation of silicon and other dopant is carried out under ultra high vacuum (UHV) pressures of the orders […]

Vapour Phase Epitaxy

Vapour Phase Epitaxy: In chemical vapour deposition (CVD), the film is formed on the surface of the substrate by thermal decomposition and or the reaction of various gaseous compounds. As in CVD, the epitaxial layer is formed from the gaseous vapour phase, hence it is called vapour phase epitaxy. The process of CVD growth takes […]

Basic Planar Processes in IC Fabrication

Basic Planar Processes in IC Fabrication The Basic Planar Processes in IC Fabrication are as listed below. Crystal growth and wafer preparation Epitaxial growth Oxidation Lithography Reactive plasma etching Diffusion Ion implantation. Metallization. Assembly techniques and packaging Let us study each process in detail one by one. Crystal Growth and Wafer Preparation In this process […]

Integrated Circuits Classification

Integrated Circuits Classification: Depending upon the functional utility, the Integrated Circuits Classification are classified as linear ICs and digital ICs. From the point of view of structural considerations, ICs can be divided as monolithic ICs, thick-thin film ICs and hybrid ICs. The monolithic ICs are most common type of IC. In the monolithic ICs, all […]

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