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Author Topic: What acids react with silicon?  (Read 6317 times)

Offline Dr.IC

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What acids react with silicon?
« on: 04/03/2009 09:49:32 »
Which acid reacts with Si.
« Last Edit: 05/03/2009 21:23:11 by chris »


 

blakestyger

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Re: What acids react with silicon?
« Reply #1 on: 04/03/2009 10:04:03 »
HF etches the oxide - used in glasswork. Is this what you meant?
 

Offline lightarrow

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Re: What acids react with silicon?
« Reply #2 on: 04/03/2009 12:38:31 »
Which acid reacts with Si.
HF dissolve Si too, but only if it's not in crystalline form. In crystalline form no acid can attack it.
It can be attacked by hot, concentrated sodium or potassium hydroxide:

Si + 2OH- + H2O  -->  SiO32- + 2H2

Among gasses, F2 attacks it at cold, Cl2 and Br2 at 300C, O2 at 400C.
« Last Edit: 04/03/2009 12:41:40 by lightarrow »
 

Offline techmind

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Re: What acids react with silicon?
« Reply #3 on: 04/03/2009 17:32:21 »
Which acid reacts with Si.
Why do you ask?
 

Offline Dr.IC

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Re: What acids react with silicon?
« Reply #4 on: 05/03/2009 04:09:16 »
HF etches the oxide - used in glasswork. Is this what you meant?
its not SiO2, its Silicon cap in IC.
 

Offline Dr.IC

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Re: What acids react with silicon?
« Reply #5 on: 05/03/2009 04:10:40 »
Which acid reacts with Si.
HF dissolve Si too, but only if it's not in crystalline form. In crystalline form no acid can attack it.
It can be attacked by hot, concentrated sodium or potassium hydroxide:

Si + 2OH- + H2O  -->  SiO32- + 2H2

Among gasses, F2 attacks it at cold, Cl2 and Br2 at 300C, O2 at 400C.
thanks i will try this..
 

Offline Dr.IC

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Re: What acids react with silicon?
« Reply #6 on: 05/03/2009 04:12:12 »
Which acid reacts with Si.
Why do you ask?
i need to remove a Si cap which covers MEMS in an IC.
 

Offline Dr.IC

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Re: What acids react with silicon?
« Reply #7 on: 05/03/2009 04:13:16 »
how to prepare aqueous KOH solution.
 

Offline lightarrow

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Re: What acids react with silicon?
« Reply #8 on: 05/03/2009 08:10:21 »
how to prepare aqueous KOH solution.
Dissolving KOH in water. Add little amounts of water to a fixed amount of KOH, till the water is slightly enough to dissolve it; in this way you have a concentrated solution. Remember that it should probably be hot and you will probably need some time for etching, but I'm not sure because I've never done this.
 

Offline Dr.IC

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Re: What acids react with silicon?
« Reply #9 on: 05/03/2009 08:28:03 »
how to prepare aqueous KOH solution.
Dissolving KOH in water. Add little amounts of water to a fixed amount of KOH, till the water is slightly enough to dissolve it; in this way you have a concentrated solution. Remember that it should probably be hot and you will probably need some time for etching, but I'm not sure because I've never done this.
thanks ..
i will try this..

 

Offline Bored chemist

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Re: What acids react with silicon?
« Reply #10 on: 05/03/2009 19:57:49 »
If you add a small amount of water to soild KOH it wil get very hot. Quite possible hot enough to boil and spatter the solution.
Since hot concentrated KOH solution is very corrosive I would advise that you do not do this.

Weigh out roughly equal amounts of KOH and ice. Put them both in the same beaker and stir carefully.
Gloves are a good idea and some sort of eye protection is a requirement. Also, if you are doing this with more than a few grams of material you really need to make sure you hev lots of fresh water to wash the stuff away if you spill it.

This stuff is a nasty corrosive mixture, remember that.

What are you actually trying to do? There may be an easier way.
 

Offline lightarrow

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What acids react with silicon?
« Reply #11 on: 06/03/2009 12:30:03 »
Also he shouldn't of course do it in a container that can be attacked from the strong alcali solution, for example glass.
 

Offline Dr.IC

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What acids react with silicon?
« Reply #12 on: 07/03/2009 09:28:16 »
If you add a small amount of water to soild KOH it wil get very hot. Quite possible hot enough to boil and spatter the solution.
Since hot concentrated KOH solution is very corrosive I would advise that you do not do this.

Weigh out roughly equal amounts of KOH and ice. Put them both in the same beaker and stir carefully.
Gloves are a good idea and some sort of eye protection is a requirement. Also, if you are doing this with more than a few grams of material you really need to make sure you hev lots of fresh water to wash the stuff away if you spill it.

This stuff is a nasty corrosive mixture, remember that.

What are you actually trying to do? There may be an easier way.

I am trying to etch Si cap which is covering the MEMS on Integrated circuit.
 

Offline Dr.IC

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What acids react with silicon?
« Reply #13 on: 07/03/2009 09:42:26 »
Hi guys
   Thanks for your valuable suggestion, if u have some more suggestion, please reply to the post.  :)

 
 

Offline Dr.IC

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What acids react with silicon?
« Reply #14 on: 10/03/2009 03:01:59 »
What is organometallic compound?
 

Offline Chemistry4me

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What acids react with silicon?
« Reply #15 on: 10/03/2009 03:09:58 »
Any compound that contains a carbon-metal bond is a organometallic compound.
For example, chlorobenzene reacts with magnesium metal in ether to give phenylmagnesium chloride.
 

Offline Dr.IC

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What acids react with silicon?
« Reply #16 on: 10/03/2009 04:32:43 »
Then molybdenum hexa carbonyl and tungsten hexa carbonyl is also a organometallic compound. what is the chemical properties of this compound.
 

Offline Chemistry4me

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What acids react with silicon?
« Reply #17 on: 10/03/2009 05:24:04 »
molybdenum hexa carbonyl and tungsten hexa carbonyl is also a organometallic compound. what is the chemical properties of this compound.

Quote
A recurring minor debate in some chemical circles concerns the definition of an "organometallic" compound. Usually, organometallic indicates the presence of a metal directly bonded via a M-C bond to an organic fragment, which must in turn have a C-H bond. By this strict definition, Mo(CO)6 is not organometallic.

http://en.wikipedia.org/wiki/Molybdenum_hexacarbonyl

---------
I don't know much about their properties so have a look at these links:

http://en.wikipedia.org/wiki/Molybdenum_hexacarbonyl
http://www.reciprocalnet.org/recipnet/showsamplebasic.jsp?sampleId=27344468

http://en.wikipedia.org/wiki/Tungsten_hexacarbonyl

 

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What acids react with silicon?
« Reply #17 on: 10/03/2009 05:24:04 »

 

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