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    Why is silicon used in chips ?

    Hello I'm new to here. I'm trying to find out why silicon is used in chips and wondered if anyone could explain this.

    And what is the qualification need for jobs in semiconductor?

    thanks!

    •   Alt2nd December 2006, 00:42

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    Re: why Si?

    Silicon is far more abundant than any other source of semiconductor material,
    you can actually extract silicon on sand, germanium is the second abundant material and the others are which i dont know.



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    Re: why Si?

    This is because silicon can be made with unusually high purity and it has a lattice constant that will accept group 3 and 5 atoms. Silicon oxide is a good diffusion shield.

    Germanium is superior in the mobility area but cannot be made as pure and germanium oxide is not as good a diffusion shield.



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    Re: why Si?

    HI , silicon is semiconductor ,u can see the properties of silicon in the book \"INTEGRATED ELECTRONICS'' by milliman -halkias inin the chapter 1 or 2,and for the job qualification u should have knowledge in microelectronics.u should be at least M.E /MTech in microelectronics/vlsi/ic technology



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    Re: why Si?

    As written before, silicon is a semiconductor element, so its electrical properties classifies semiconductors as not so good electrical conductors and no perfect isolators. This is because they have 4 electrons in their valence layer of electrons. So silicon alone is not useful for electronic devices. When some impurities are inserted in the crystaline structure of the pure silicon crystal, the material changes their electrical properties becoming more conductive and with electrical fields properties. The insertion of some Boron or Phosphorus atoms (the impurities) in the silicon structure, creates the N or P type semiconductors with free holes or electrons in the structure. After this, layers of N and P type semiconductors are arranged to form the semiconductors devices (transistors, diodes, triacs, scrs, mosfets, etc).


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    why Si?

    Another reason for use of Si compared to Ge is its high temperature tolerance.



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    Re: why Si?

    I have somethin 2 say regardin qualification for getting a job in semiconductor industry.. IN designing side u need 2 have a project experience. U shud be a Btech in E&C + u shud have done a PG diploma in VLSI. Or else masters in vlsi is more prominant.. Well since u have asked abt Silicon I think Ur asking for jobs in Fabrication industry. Well for fab jobs metallurgy & physics shud be the main subjects in your degree. All these stated with my limited knowledge. Correct if I am wrong..



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    Re: why Si?

    Si is a semiconductor device which falls between conductors and insulators. It enables to have components which allow unidirectional flow of current and also such components which allow us to have a rapid switching action.
    Now the point of using Si over Ge is that Si can work over a larger temperature range than Si. Also the leakage current in Si devices is much less than the Ge devices.



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    Re: why Si?

    Well... I guess

    1. Ease of extraction
    2. Temperature tolerance
    3. Less leakage Current and
    4. Faster Swichig
    are the reasons.



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    Re: why Si?

    because of its stability over a range of temperature see the structure of silicon and germemium u can see the difference why we use it and after careful examination read falowing reason

    because a little temperature variation cause the device to be unstable so we use silicon and it is cheap too

    most stable at temperature is GaAs but it is very expensive



    •   Alt29th December 2006, 20:43

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    Re: why Si?

    not only silicon , any semiconductor element can be used.
    silicon is widely used because of availability and fabrication cost .

    http://hyperphysics.phy-astr.gsu.edu...s/sili.html#c1
    http://hyperphysics.phy-astr.gsu.edu...s/dope.html#c4



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    Re: why Si?

    I want to add my 2 cents worth.

    All of what has been said is true but I believe the main reason silicon is used so widely is the fact that it grows a stable high quality oxide. Many of the other semiconductors do not form a stable quality oxide.

    DrProf



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    Re: why Si?

    as our friends said that above all true once again according to me
    since conductors having positive temparature coefficient of resistance it should not useful for all conditions.but due to negive negitive temparature coefficient we should prefer semiconductors.
    so any semiconductors like ge ,si,gaAs, we can use
    but most preferbly si because

    high avaialability
    high purity of oxides avaliable
    less leakage current
    high temparature tolarance
    less cost
    fabrication process is easy


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    Re: why Si?

    I really appriciate all! Thanks so much!

    Actually I'm an oversea student studying in an English-speaking country for electronic diploma. Language is big problem to me, I usually need to take long time to understand content I've learnt. But I'll try my best to overcome it.

    :D



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    Re: why Si?

    actually, the world is going to use PLASTIC instead of SILICON, but giant companies invested a lot in their plants (see the last news in the domain)
    i understand ur question was a rhetoric one ?



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    Re: why Si?

    And I gather all answers about Si:

    1. abundant semiconductor (sand)
    2. high purity
    3. lattice constant
    4. SiO2 is a good diffusion shield ???
    5. high temperature tolerance
    6. allow unidirectional flow of current
    7. some related components have a rapid switching action ???
    8. Less leakage Current
    9. low availability and fabrication cost
    10. grows a stable high quality oxide
    11. Semiconductor has negitive temparature coefficient ???
    12. fabrication process is easy

    some I'm still not very clear, like why high purity? due to its crystal structure?

    And why material could affect the current follow direction? I just know the ohmic contacts could allow current in both directions.

    Im sorry I dont know what the switching action & negitive temparature coefficient are?

    And I think I also need to know more about its oxide and other related techniques.

    Thanks!!!

    Added after 9 minutes:

    Quote Originally Posted by zolam
    actually, the world is going to use PLASTIC instead of SILICON, but giant companies invested a lot in their plants (see the last news in the domain)
    i understand ur question was a rhetoric one ?
    Maybe my question is a little stupid, but i really wonder to know it well. I hope work in this field in future.



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    why Si?

    silicon based semiconductor is most deeply researched in semiconductor material physics, and most mature in process, for mass production



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    Re: why Si?

    hi,

    initially Vacuum tubes was used to control the follow ....... then 1947 in bell lab transistor is invented coz in which semiconductor material (Germaninum) was used

    why semiconductor used......
    Answer is that in only semiconductor has the property to control the follow of current by changing the impurity level that is why we used semiconductor.

    there are various semiconductors available why silicon is used......
    Answer is that Si has good thermal and electrical property as compared to other semeconductor and our earth crest consist of silicon so it is very easily available


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    Re: why Si?

    The three semiconducting elements (Si, Ge, and Sn) from column IVA of the periodic table serve as a kind of boundary between metallic and nonmetallic elements. Silicon (Si) and germanium (Ge), widely used elemental semiconductors, are excellent examples of this class of materials. [Another important semiconductor material is GaAs, a compound of the group IIIA element Ga; and the group V element, As.]


    Silicon is a semiconductor, which means that its electrical behavior is between that of a conductor and an insulator at room temperature. With the proper addition of dopant elements, p-n junctions can be formed on silicon. Useful electronic components and integrated circuits can be built from p-n junctions. Silicon is obtained by heating silicon dioxide (SiO2), or silica, with a reducing agent in a furnace. Silicon dioxide is the main component of ordinary sand.


    Aside from being used as semiconductor substrate, silicon is also widely used as dielectric in integrated circuits, usually in the form of silicon dioxide. Dielectric layers are used to isolate conductive lines and the individual components in the circuit from each other. Polycrystalline silicon, or polysilicon, is also used for making resistors or conductors in integrated circuits. The top glassivation used to mechanically and electrically protect the die is also usually composed of silicon in the form of silicon nitride. Silicon is also widely used in semiconductor packaging, being the main ingredient of plastic encapsulants for integrated circuits. Silicon is also used in die overcoats.


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    why Si?

    major factor which decides the material is the thermal stability at higher temperature...

    well only other material that can be used is the germanium but it is not thermally stable so they dont use it and moreover at higher frequency it is not stable too....



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