Regarding composition of the deposited alloy, you may need to optimize the sputtering process for your machine. The primary parameters are power and pressure during deposition. Time/duration of sputtering primarily governs the deposited layer thickness, not composition.  

You can do few trial runs by varying the primary parameters (one at a time). Then composition of the deposited alloys can be tested from experiments like XPS etc. Once you get the required composition, you can use it for future process.

If in-situ thickness monitor is unavailable and deposited layer thickness is also a concern, then another 3 runs for different duration can give you the idea of deposition rate.    

The parameters you can change during DC magnetron sputtering deposition are 1) power, 2) pressure, 3) substrate bias, 4) target composition, 5) distance target-sample and rotation, 6) magnets configuration, 7) substrate temperature, 8) vacuum system.

1) According to your power supply, you can choose to keep constant power or current.

2) Voltage, current, and pressure are not independent parameters. At a fix power and temperature, pressure variations can influence the microstructure, like roughness and grain size.

3) Substrate bias is also very important: a) if you run at floating bias (substrate isolated from ground) you will get a low amount of ion bombardment; b) if you do it with a grounded substrate, your sample will be bombarded by electrons during deposition; c) if you have a bias higher (in absolute terms) than the floating bias, you will have a lot of ion bombardment.

4) Target composition is also very important. As the components have different "sputtering rate", one of the components coud sputter faster than the other one. So if you start with fix composition, you usually get a different one. It is also important the way you manufacture the target: is it a solid solution? what is the grain size? Or it is a target made with pieces of the components?

5) The distance target-substrate and rotation also influence what you get deposited. If the distance is too short, you could have heating from the target. If you do not rotate, you could have compositional gradient if your target is not uniform or you are doing co-deposition from two targets.

6) The magnets configuration in co-deposition systems is very important.Is it unbalanced or balanced magnetron? Do you know that your deposition rate depends strongly on the magnet strength of a magnetron cathode, even when you have only one magnetron?The ,magnetic field of the magnetron strongly influence the plasma conditions during the deposition. It is wise to make a plasma characterization of your system using Plasma Probes.

7) Substrate temperature also influences what you deposit. Higher temperature gives more mobility to adatoms over the surface, so you get bigger grain sizes. Also, high temperature could influence segregation in composite materials. Remember that even if you don't heat your sample, the plasma heats the substrate according to the plasma conditions.

8) How good is your vacuum system? If you have a bad pressure or water, you will get also lot of oxygen!

I hope that what I have been writing will help you: as you see, it is not easy! I suggest you to look in a good book or review paper about DC magnetron sputtering. Good luck!

Thank You Esteban. I have one other query. Assuming my composition is Cu93.5W6.5 how do I choose the power for this composition. Is there a technique for this? Also assume I have to grow 200nm of the above composition.

with different kind of gases,voltage ,current and pressure you can keep constant and work..

Since you have alloy target (Cu93-.5W6.5)

I would say begin firstly at some point, and make one deposition run first.

A convenient pressure, and 100W on the target, get a stable plasma, and try to deposit a film. Check the composition of the film by EDAX, and see the uniformity of the composition in the film Cu/W elemental ratio, and check if you are able to replicate the target composition or not. Also check the phase through X-ray diffraction.

You should not end with a simple Cu film with no tungsten.

If not satisfied, then you have to play carefully with the variation of pressure, power and substrate to to target distance.

Substrate temperature may help you sometimes in establishing the right phase in the film, as you have to react the Cu and W atomic specie reaching the substrate.

Copper is a very fast sputtering material so be careful, not to increase you sputter power and deposition too long, it will simple sputter out the Cu from the target, and the whole target composition itself will change.

K. Sreenivas

Power and sputtering yield could give you the exact percentages I believe. Gas flow and pressure would not effect your composition as it will be same for both so you shouldn't worry about it.

may i ask, what indian author books do you recommend as reference in magnetron sputtering

May I know anyone is aware of the vacuum condition required in the Cu deposition in the magnetron sputtering on the alumina substrate. Al2O3. ????