The advantages depend on your intentions, but generally speaking Ar is chemical inert (as a noble gas) its comparably easy to ionize and it's the cheapest of all noble gases.

For surface modification Ar is good for sputtering as the Ar ions have a high mass and there is no surface chemistry going on with argon.

Well. Your question is incorrect. Any plasma is excited to resolve a special problem: cleaning, etching, etc .Johannes said already that Ar is chippest (among other noble gases) and chemically inert. What is important, ion sputtering by plasma ion results among others an implantation of the ions into a near surface layer. Because of a very low surface binding energy of Ar, the concentration of implanted Ar is very low. For example, oxygen implantation in Si results SiO thin film formation.

Argon is inert that prevents the surface oxidation. HElim and Neon are others.

The impact of the light noble gas ions is small, so surface modifications occur with a lower rate compared to the use of Ar. For example, if you want to clean a surface with Helium, it will take you hours to remove an adsorbate layer (see e.g. 10.1016/S0022-0728(97)00340-9), while the same adsorbate will be removed by Ar sputtering within fractions of a second ...

But I agree with Yuriy, using reactive ions may also be quite effective for other surface modifications (e.g. activation of polymer bonds prior to a coating process, etc). Kind regards, Dirk

Argon usually needs low energy for plasma generating. in surface engineering of polymers for biomedical use argon plasma is usually used for physical surface modification, in comparison to N2 or O2 plasma which mostly used for chemical surface modification

Understood by Argon high kinetic energy bombardment onto Si surface, it may lead hydrophilic surface condition after some wet chemicals, eg. HF/H2SO4/HNO3/HSPO4 treatment on the Si surface. Is there any details explanation why hydrophilic surface after Argon with wet chemicals treatment process on Si ?

Mr Johannes_Gruenwald ,

Is it possible to have plasma without argon gas? Suppose I want reactive ion etching can it be possible to get plasma of O2 only? 

Basanta Kumar Parida

   Yes, it is possible to produce O2 plasma without argon gas. The oxygen plasma requires high voltage to produce plasma.

Thank you Vinisha.

Because argon plasma does not oxidise a surface, it is employed in a variety of metal cleaning applications, including wire bonding.

Also, because Argon is a heavier gas than H or He, its ions have more energy to treat the surface of the substrate that needs to be treated.