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Introduction

While the physical properties of silica make it suitable for use in protective and optical coating applications, the biggest application of insulating SiO 2 thin films is undoubtedly in semiconductor devices, in which the insulator performs a number of specific tasks, including: surface passivation, field effect transistor (FET) gate layer, isolation layers, planarization and packaging.

The term insulator generally refers to a material that exhibits low thermal or electrical conductivity; electrically insulating materials are also called dielectrics. It is in regard to the high resistance to the flow of an electric current that SiO 2 thin films are of the greatest commercial importance. The dielectric constant (ε) is a measure of a dielectric materials ability to store charge, and is characterized by the electrostatic energy stored per unit volume across a unit potential gradient. The magnitude of ε is an indication of the degree of polarization or charge displacement within a material. The dielectric constant for air is 1, and for ionic solids is generally in the range of 5 - 10. Dielectric constants are defined as the ratio of the material’s capacitance to that of air, i.e., [link] . The dielectric constant for silicon dioxide ranges from 3.9 to 4.9, for thermally and plasma CVD grown films, respectively.

An insulating layer is a film or deposited layer of dielectric material separating or covering conductive layers. Ideally, in these application an insulating material should have a surface resistivity of greater than 10 13 Ω/cm 2 or a volume resistivity of greater than 10 11 Ω.cm. However, for some applications, lower values are acceptable; an electrical insulator is generally accepted to have a resistivity greater than 10 5 Ω.cm. CVD SiO 2 thin films have a resistivity of 10 6 - 10 16 Ω.cm, depending on the film growth method.

As a consequence of its dielectric properties SiO 2 , and related silicas, are used for isolating conducting layers, to facilitate the diffusion of dopants from doped oxides, as diffusion and ion implantation masks, capping doped films to prevent loss of dopant, for gettering impurities, for protection against moisture and oxidation, and for electronic passivation. Of the many methods used for the deposition of thin films, chemical vapor deposition (CVD) is most often used for semiconductor processing. In order to appreciate the unique problems associated with the CVD of insulating SiO 2 thin films it is worth first reviewing some of their applications. Summarized below are three areas of greatest importance to the fabrication of contemporary semiconductor devices: isolation and gate insulation, passivation, and planarization.

Device isolation and gate insulation

A microcircuit may be described as a collection of devices each consisting of "an assembly of active and passive components, interconnected within a monolithic block of semiconducting material". Each device is required to be isolated from adjacent devices in order to allow for maximum efficiency of the overall circuit. Furthermore within a device, contacts must also be electrically isolated. While there are a number of methods for isolating individual devices within a circuit (reverse-biased junctions, mesa isolation, use of semi-insulating substrates, and oxide isolation), the isolation of the active components in a single device is almost exclusively accomplished by the deposition of an insulator.

Questions & Answers

encoding is the last step in memory stracture
FARWA Reply
crow and angle have feathers and can fly " it is a connective concept
FARWA
my mother always take decision based on reasoning ; she is practicng realistic thinking .
FARWA
all human are mortal is a formal concept
FARWA
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FARWA
echoic memory reflect humans visual system
FARWA Reply
getting the information back from stored area of brain is called retrieval
FARWA
no , echoic memory reflect upon things you hear , that's Iconic memory which deals with visual information
Nancy
I'll be studying psychology soon. Where do I start?
Jane Reply
I would start by learning basic terminology and definitions cause there's a lot of it and learning the different concepts behind psychology and there meanings and there use then go onto introduction into psychology
why is psychology a science?
Godslove Reply
it's a social science
Alex
what we define as science is a systematic arrangement of knowledge based on experimental and observational data.so psychology is a science. as for what kind of science it is depends on how and what information are you using in your approach towards understanding the said data and to what conclusion.
imirror
depending on your approach and understanding Psychology can classify as medical or social science like anthropology
imirror
your friend is under stress because she has not prepared well for the examination what strategies would you suggest her? express in 100 or 150 words
Masi Reply
hello
Masi
yess
dcs
where on the disorders does paranoid thought come in?
Hot Reply
hot shots will give you paranoid thoughts
Kimberly
Kimberly 😂😆😂 yes hot shots will give you paranoid thoughts
Brandon
what compound motivation is attention extension
Gauri Reply
what is psychology
Drishti Reply
The scientific study of the mind
Gina
scientific study of mind and behaviour
Siva
...
Saeed
Scientific study of mind soul behaviour and experiences
Ayush
scientific srtudy of behaviour and cognitive processes
Reshmi
Apply social psychology on real life in Nigerian universities campus
tyosaa Reply
what is the meaning of an idiosyncratic pattern
Krystle Reply
I am here for the first time just here to learn...
michael Reply
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Lisa
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GOPAL
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jennifer
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jennifer
Suppose an individual with OCD experiences obsessive thoughts about germs, contamination, and disease whenever she encounters a doorknob. What might have constituted a viable unconditioned stimulus? 
la Reply
What are factors that influence learning?
Enos Reply
Environment Heredity(I am not sure about heredity)
Tusita
Helpful. .. thanks
Enos
Sure, anytime
Tusita
I have other questions also
Enos
Based on the factors affecting learning, how do we improve learning
Enos
I think that addressing that everyone learns in their own time
James
Peer group influence can also be another reason
Sorie
Also knowing what's going on at home. what pressure are the parents putting on them.
James
am I close or no
James
also is there a lack of care? going one more step. with peer groups do an activity that shows how much they have in common
James
I think one's society has a big role to play in determining what/when & how he/she learns.
BECHEM
multiple reasons at different stages. at the earliest stages of development in a child is behaviour of people around. A baby starts learning basic social expressions and actions by mimicking the people around it. further social and cultural practices enforces learning and behaviour
imirror
from need to nutrition everything affect development and learning when choosing on a single factor of influence it is necessary to keep these other factors in the mind as environment around people is very plastic and flexible and there are many variables playing active role
imirror
social interaction is surely a big influence hence can be used to improve learning.
imirror
to encourage learning it is important to establish curiosity and notion of possibility for more perspectives habit of questioning possibilities and cause and effect in a great way to encourage learning in my opinion. language is another important factor
imirror
under what schedule of reinforcement do animals learn from ?
Phelisa Reply
the role of emotional intelligence in a courtship behavior
Caren Reply
1
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Source:  OpenStax, Chemistry of electronic materials. OpenStax CNX. Aug 09, 2011 Download for free at http://cnx.org/content/col10719/1.9
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