system
Given the following post, respond as if you're commenting on Reddit:
human
Why is argon used in sputtering PVD processes?

Last week during a lecture about PVD and sputtering my professor showed a graph of sputter yield for each atomic number, and it looked like the opposite of atomic radii for each atomic number, the yield goes up as you move to the right in the periodic table, and drops down when you move from a noble gas to an alkali metal. He said this graph explains it because argon has the highest yield, but it doesn't. Every noble gas below it in the periodic table has better yield (according to that graph).
My question is - why use argon? And what makes noble gases have the best yield for their row in the periodic table?
gpt
For the best momentum transfer you want the sputtering gas to have a similar mass to the target atoms so the ideal gas depends on what elements you're using - sometimes neon or krypton or whatever is more suitable. Argon is also the cheapest noble gas. Noble gases are good because they're chemically inert.