VLSI

Gallium Arsenide (GaAs) Fabrication Techniques: This article is used to describe the basic fabrication methods of Gallium Arsenide (GaAs), mainly using LEC Growth process. Various methods are used for the fabrication of Gallium Arsenide (GaAs). Out of all the methods, the main growth technique that is used is the liquid-encapsulated Czochralski (LEC) growth of  GaAs  […]

Metal Semi-conductor FET (MESFET) This article briefly describes the structure of MESFET , its comparison with MOSFET, D-MESFET and E-MESFET, circuit symbols, and also the characteristics of Schottky Barriers. A post on MESFET has already been discussed. TAKE A LOOK : MESFET This post also gives a brief description of MESFET and the main classification

Gallium Arsenide (GaAs) Devices In this article, the first and second generation types of Gallium Arsenide (GaAs) devices are explained. During the last few years a number of different devices have been developed. MESFET was regarded as one of the earliest type of GaAs devices. The so-called ‘first generation’ of GaAs devices includes: Depletion-mode metal

Gallium Arsenide (GaAs) – Electron Velocity-Field Behaviour In this post, the graph between the electron field and the electron velocity is explained. The reason for the decrease in the drift velocity of the electrons have also been explained in detail. The charge carriers in the GaAs material that is the electrons will obtain energy as

Gallium Arsenide (GaAs) – Energy Band Structure In this article, the energy band structure of GaAs is explained with a diagram and also with respect to its comparison with Silicon. The cause of the curves in the valence band and conduction band of GaAs is thoroughly explained. Electron Mobility, a characteristic of GaAs, and its

Gallium Arsenide (GaAs) – Channeling Effect This article explains the channeling effect of Gallium Arsenide (GaAs), and its orientation dependency. The concept of axial channeling is also explained. Before going into details, it is better to know the basics on GaAs in VLSI technology. Click on the link below. TAKE A LOOK : ULTRA-FAST SYSTEMS

Gallium Arsenide (GaAs) Doping This article briefly explains the compound semiconductor Gallium Arsenide (GaAs) with a figure showing the arrangement of atoms. The Gallium Arsenide (GaAs) doping process, with respect to the p-type and n-type material is also explained with diagrams. Before going into details, it is better to know the basics on GaAs in

In this post, the origin of Gallium and Arsenic, as well as the structure and properties of the Gallium Arsenide (GaAs) crystal is explained in detail. The atomic structure of Gallium and Arsenic are explained with diagrams and also compared with Silicon. The valence configuration of Ga, As and Si is also shown. Before going

Ultra-fast Systems and GaAs VLSI Technology In this post, we will briefly review some of the limitations of silicon devices and then look at the emerging alternative for ultra-fast systems — gallium arsenide. Submicron CMOS technology Speed and smaller device dimensions are closely interrelated and we have already touched on the fact that the foreseeable

V-Groove MOS (VMOS) This article explains in detail about the structure of VMOS with diagram, its characteristics, anisotropic etching and also the applications of VMOS. To know the basics, click on the links given below. TAKE A LOOK : SHORT CHANNEL MOS STRUCTURES VMOS Structure The structure of VMOS is similar to short-channel power FET

Double-Diffused MOS (DMOS) In this article, the Double-Diffused MOS (DMOS) structure is explained with a diagram. The working of Vertical DMOS Transistor is also explained in detail with its structural analysis and diagram. To know the basics of DMOS take a look at the following posts. TAKE A LOOK : SHORT CHANNEL MOS STRUCTURES The

Short Channel MOS Structures This article discusses the different factors that limit the speed of a MOSFET. The common methods to reduce the parasitics like Scaled MOS (SMOS) and High-performance MOS (HMOS) is explained in detail with their structure and diagram. There are many factors that limit the speed of a MOSFET. Because of the

NMOS Fabrication Process In this article the various steps needed for NMOS Fabrication are explained in detail along with diagrams. To know the basic IC Fabrication Techniques, click on the link below. TAKE A LOOK : IC FABRICATION TECHNIQUES There are a large number and variety of basic fabrication steps used in the production of

PMOS vs NMOS The advantages of n-channel MOSFET’s over p-channel MOSFET’s and vice versa have been explained in detail. Even the problems that NMOS faces in device processing and oxidation have also been explained. n-channel MOSFETs have some inherent performance advantages over p-channel MOSFET’s. The mobility of electrons, which are carriers in the case of

MOSFET Technology and Various MOS Process This article focuses on basics of MOSFET Technology,basics of various MOS process like p-channel MOS (PMOS), n-channel MOS (NMOS), Complimentary MOS (CMOS) – its manufacturing, cross section, and other advantages of one over other. Most of the LSI/VLSI digital memory and microprocessor circuits is based on the MOS Technology.

Dielectric Isolation in Integrated Circuits This article focuses on Dielectric isolation in various Integrated Circuits; especially in the VLSI sector, discusses various methods used for dielectric isolation like V-groove isolation, Silicon on Insulator technology and Epitaxial layer overgrowth. Dielectric isolation, as you all know, is the process of electrically isolating various components in the IC

The figure below shows some IC JFET structures. The n-channel JFET structure of first figure [a] is compatible with the n-p-n transistor fabrication sequence. Another view of this n-channel JFET is shown in second figure [a], where we note that the top p+ gate region extends beyond the n-type epitaxial layer region to make contact

Monolithic Planar Diode Configurations We have seen that in the fabrication of an IC the geometry and the doping of the various layers must be chosen to optimize uncharacteristic of the transistor which is the most important device. It is not economically feasible to provide extra processing steps to fabricate diodes. Therefore diodes are generally

Once all components are fabricated on a single crystal wafer, they must be electrically isolated from each other. The problem is not encountered indiscrete circuits, because physically all components are isolated. There are two methods of isolation in Integrated circuits. They are P-N  junction isolation and Dielectric isolation In this post we shall discuss p-n

In this post, we shall discuss, the fabrication of a standard, junction- isolated bipolar IC.  Of course, many devices can be formed at a time over the surface of the water if appropriate patterns are provided. We shall show only one device, that is, a bipolar transistor as an example. The major steps in the

The figure below shows a diagram of gallium arsenide (GaAs) MESFET (metal-semiconductor field-effect transistor). MESFET is nothing but a JFET fabricated in GaAs which employs a metal-semiconductor gate region (a Schottky diode). The device operates in essentially the same way as does a junction-gate FET, except that instead of a gate-channel on junction there is

Junction Characteristics Before describing the fabrication sequences for ICs, it will be useful to provide insight into the use of epitaxial structures for devices. A reverse-biased p-n junction can be considered to be a parallel-plate capacitor with the depletion region being the insulator or dielectric as shown in the figure below. The depletion or space-charge

To know about the different IC fabrication techniques, click on the link below. TAKE A LOOK : IC FABRICATION TECHNIQUES Metallization is the final step in the wafer processing sequence. Metallization is the process by which the components of IC’s are interconnected by aluminium conductor. This process produces a thin-film metal layer that will serve

To know about the different IC fabrication techniques, click on the link below. TAKE A LOOK : IC FABRICATION TECHNIQUES ION IMPLANTATION Ion Implantation is an alternative to a deposition diffusion and is used to produce a shallow surface region of dopant atoms deposited into a silicon wafer. This technology has made significant roads into

To know about the different IC fabrication techniques, click on the link below. TAKE A LOOK : IC FABRICATION TECHNIQUES Diffusion of Dopant Impurities The process of junction formation, that is transition from p to n type or vice versa, is typically accomplished by the process of diffusing the appropriate dopant impurities in a high