Double-Diffused MOS (DMOS)

john February 9, 2011 2 Comments
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 figure below shows a double-diffused MOS (DMOS) structure. The channel length, L, is controlled by the junction depth produced by the n+ and p-type...
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Short Channel MOS Structures

john March 21, 2011 1 Comment
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 parasitic capacitances and resistances, the change in the channel current and output voltage  occur slowly. This is due to the fact that when the...
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NMOS IC Fabrication Process

john March 21, 2011 4 Comments
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 modern MOS ICs. The same process could be used for the designed of NMOS or PMOS or CMOS devices. The gate material could be...
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john February 9, 2011 2 Comments
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 an n-channel device, is about two times greater than that of holes, which are the carriers in the p-channel device. Thus an n-channel device...
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MOSFET Technology

john February 15, 2011 4 Comments
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. More transistor and circuit functions can be achieved on a single chip with MOS technology, which is the considerable advantage of the same over...
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Dielectric Isolation

rahul February 3, 2011 8 Comments
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 chip from the substrate and from each other by an insulating layer. It’s main use is to eliminate undesirable parasitic junction capacitance or leakage...
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Monolithic Junction FET’s

john July 14, 2010 3 Comments
The figure below shows some IC JFET structures. The n-channel JFET structure of first figure is compatible with the n-p-n transistor fabrication sequence. Another view of this n-channel JFET is shown in second figure , where we note that the top p+ gate region extends beyond the n-type epitaxial layer region to make contact with the p-type substrate bottom gate. The n-type channel is thus completely encircled by the gate structure and the application of a suitably large...
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Monolithic Diodes

john July 13, 2010 2 Comments
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 transistor adopted for this operation. There are basic five configurations of transistor for diode operation as shown in the figure below. A base-collector diode...
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P-N Junction Isolation

john July 1, 2010 No Comments
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 junction isolation. The method of isolation is most compatible with the IC processing, that is, one extra processing step, other than required to fabricate...
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Bipolar IC Manufacturing Process

john June 30, 2010 No Comments
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 IC bipolar process are listed in the diagram below. The starting material is a p-type single crystal silicon wafer having 5 to 20 ohm-cm...
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