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What is Physical Vapor Deposition?

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  • Written By: M. Walker
  • Edited By: Allegra J. Lingo
  • Last Modified Date: 05 November 2016
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Physical vapor deposition (PVD) is a process used to create thin films by transferring a target material onto a substrate. The transfer is achieved through purely physical means unlike chemical vapor deposition, which uses chemical reactions to create the thin films. Semiconductors, computer chips, compact discs (CDs), and digital video discs (DVDs) are usually created by this process.

There are three main types of physical vapor deposition: evaporation, sputtering, and casting. Evaporation techniques begin by placing the target material into a vacuum chamber, which reduces the pressure and increases the rate of evaporation. The material is then heated to boiling, and the gaseous particles of the target material condense on the surfaces of the chamber, including on the substrate.

The two main heating methods for physical vapor deposition by evaporation are electron beam heating and resistive heating. During electron beam heating, a beam of electrons is directed at a specific area on the target material, causing that area to heat and evaporate. This method is good for controlling the specific areas of the target that are to be evaporated. During resistive heating, the target material is placed in a container, usually made of tungsten, and the container is heated with a high electric current. The method of heating used during evaporation physical vapor deposition varies depending on the nature of the target material.

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Sputtering processes also start out with the target material in a vacuum chamber, but the target is broken up by gas plasma ions rather than by evaporation or boiling. During the process, a current is run through a gas plasma, causing positive cations to form. These cations bombard the target material and knock away small particles that travel through the chamber and deposit on the substrate.

Like evaporation, sputtering techniques vary according to the target material. Some will use direct current (DC) power sources, while others will use radio frequency (RF) power sources. Some sputtering systems also employ magnets to direct the movement of the ions, while others will have a mechanism to rotate the target material.

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nony
Post 3

@everetra - There’s no difference really, in my opinion. Sputtering seems to be just as precise in its movements. The article also mentions magnetron sputtering which you gives you additional control over the ions, so I think it would work just as fine.

I have to admit however the idea of using gases seems to be a little more nebulous, but I’m not a scientist, so I am sure it’s just as effective.

everetra
Post 2

@Charred - So which of these three processes for thin film deposition would you say is the most accurate?

The article doesn’t say and perhaps there is no difference. However just at first glance I would think that the evaporation method is the best of the bunch.

I say that because it uses electron beams to direct the specific location for evaporation. Electron beams are known to be pretty precise instruments from what I understand and so I think this would be the most accurate method.

Charred
Post 1

It sounds like a pretty high tech approach to thin film coating. I think the use of the vacuum chamber is absolutely necessary to make sure that no dust particles and stuff get on the final film. At this level of detail you can’t afford the slightest smudge, I would suppose.

I used to mess with electronics as a hobby back in my teenage years and I played with electronic circuit boards. This was a way of building circuits by etching solutions onto a metal layered circuit board, revealing the circuit pattern when the solution dissolved.

It was a chemical process obviously but it’s the closest thing I have in real life that reminds me of this physical vapor deposition.

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