Understanding Plasma Sputtering: A Brief Overview

[Jayse_83]

What is plasma sputtering??

Hi,

I've got a undergrad exam coming up and i can't describe the process of plasma sputtering , can't find much on the web .. any help would be greatly appreciated

 

[jdavel]

Jayse_83,

How about if we split the work? You tell us what a plasma is, and we'll tell you what plasma sputtering is.

 

[Jayse_83]

hey, thanks for the offer but i think I've figured it out now!

 

[Danger]

hey, thanks for the offer but i think I've figured it out now!

Come back here, you! Now that you've got me all curious about this, don't you dare be buggering off without telling me the answer!

 

[Jayse_83]

lol! ok its for a nanophysics course and its a method of producing monolayers of atoms. The technique is quite simple, involving a cathode (this is made from the material you wish the monolayer to be made from) and an anode. The cathode is bombared from impacting ions from the anode and atoms from the cathode are 'spluttered' out ... sorry if its not in detail, but that's all i need to know !

 

[ZapperZ]

lol! ok its for a nanophysics course and its a method of producing monolayers of atoms. The technique is quite simple, involving a cathode (this is made from the material you wish the monolayer to be made from) and an anode. The cathode is bombared from impacting ions from the anode and atoms from the cathode are 'spluttered' out ... sorry if its not in detail, but that's all i need to know !

I'm not sure if the "name has been changed to protect the innocent", but in thin-film fabrication, this technique is typically known as DC sputtering or, if a more sophisticated method is employed, an AC magnetron sputtering.

However, without using any chemical precursor to produce a natural reaction (such as that in atomic-layer deposition), I do not know how such a technique can produce monolayer of film. All you're doing is causing the sputtered atoms/molecules to be deposited onto a substrate - hardly a controllable process to produce monolayers.

Zz.

 

[Danger]

sorry if its not in detail, but that's all i need to know!

Okay, got it now. I wasn't familiar with that term. The closest thing that crossed my mind was the nasty little explosions that you occassionaly get while arc welding. The thing that you're referring to is what I've known of as 'atomic deposition'. It's like the atomic-level equivalent of the plasma coating that we use for 'painting' metallic objects, or electroplating.

All you're doing is causing the sputtered atoms/molecules to be deposited onto a substrate - hardly a controllable process to produce monolayers.

I wonder... if the deposited atoms have a very high affinity for the substrate and a high dislike for each other, wouldn't they tend to avoid piling up?

 

[ZapperZ]

I wonder... if the deposited atoms have a very high affinity for the substrate and a high dislike for each other, wouldn't they tend to avoid piling up?

Substrate mismatch is a BIG issue in any deposition. So your choice of substrate is crucial. For example, the common substrate such as MgO and sapphire, have a huge lattice mismatch when you try to deposite GaN. As soon as you take it out, you'll see flaking and cracking on the film.

Now I've never heard of the situation that you described. Remember that in sputtering, you are sputtering out of a solid target of the material already (unless you're doing reactive sputtering or making an alloy). So you're already starting off with a material that, presumably, has no such hatred to itself. Furthermore, the deposition is typically done at high temperatures. The substrate usually is heated to maybe 500 C. This allows the sputtered gas that landed on the substrate (and the already formed film) to have enough thermal energy to rearrange themselves into the most stable configuration. So films formed this way tend to have less internal stress and are less prone to cracking.

Zz.

 

[Danger]

Now I've never heard of the situation that you described.

That's probably because it existed only in my head. I was just 'thinking out loud'. No school, remember?