Sputtering Thin Tungsten Layers on Moly Substrates

Probably, the easiest way to get a good answer is to ask the applications department of your sputtering system supplier, and/or tungsten target supplier for applications support. Depending on the history of the moly, you could need a short acid clean to remove moly compounds. You should probably also sputter-clean the surface in the vacuum to remove the mono-layer of oxide that froms quite quickly.

Thanks for your comment. My moly substrate was chemically degreased and acid cleaned before RF-sputtering.

I think you just get to the critical point by sputter-clean. How can this be done in the same vacuum sputtering chamber? Do you mean we should sputter-clean moly substrate by tungsten but in higher RF power? Will you please advise in more detail?

Going to your supplier is a good idea. You should know what pressure you are sputtering at, the power level of the Rf feed, the backing gas used in your sputter system and how long you are sputtering.

In general the lower your pressure the faster the deposition rate. Many metals can be sputtered too fast which causes poor adhesion. If you don't get good info from the supplier of your sputtering tool you can try several experiments where you vary power and others where you vary pressure.

I suggest argon as a backing gas after you have removed all other gases. Tungsten can outgas nitrogen so you may also need to check the purity of your tungsten. You may need vacuum formed targets of tungsten.

An internet search for "sputtering systems" should give you a lot of info.