Have you tried to reach a lower base pressure? And you you pre-sputter (sputtering with a closed shutter before actual deposition)?

Thank you Westerik for your knocking. I tried for base pressure up to 4x 10^-6 Torr. I did also pre-sputtering for 5 minutes. But I noticed one phenomena that the glow discharge sometimes shake with increasing power. How could I fix this problem?

Increase pre-sputtering time up to 15-20 minutes and you will find the difference in film quality. 

Thanks a lot ,  Farhat Ali. I will consider that in my next experiment, but I am worried about oxidation. Could you please give me any idea for fixing working gas pressure (3-10 mTorr) to enhance film quality and deposition rate? 

Fixing... you mean that it is not constant?

If you are woried about oxidation, try to get a lower base pressure. We usually use something like 1e-6 Torr for base pressure. If you cannot reach that pressure, it could be that there is a small air leak in your system, which could also lead to oxidation.

Deposition rate usually goes up for lower pressures and shorter target-substrate distance, but the layer uniformity will get worse. Of course higher power will also lead to a higher deposition rate. I do not really know what the influence of these parameters will be on your film quality.

Thanks a lot , Westerik. Your given suggestions will help me a lot to get the desired film quality with higher deposition rate.

hi

You can set  the target to substrate distance: 10 cm and have to use lower power(max 60 W) and growth rate.

power 100 - 200 W and  (highest rate- 161 nm/ minute and lowest rate-87 nm/ minute) are extra large parameters

Hi Perihan,

You mean that that will improve the film quality? I don't know, we sputter optically smooth aluminum films at 7 kW, with a deposition rate of about 1 um/min.

Hi Perihan. I will try for 60-100 W and i will let you know. Thank you for your suggestions. Could you have some suggestions for Ar gas working pressure? But I am using single  2"  Magnetron sputter source for deposition. 

We have got the best film quality at target-substrate distance of 7 cm. The base pressure up to 1 x 10-6 torr seems optimum. Increase the power to obtain higher deposition rate. 

Thank you , Ali. Your suggestions will be highly considerable in my experiments. I am depositing Al film on glass substrate at room temperature. Should I need substrate heating to make good film? 

You should preheat the substrate before coating for outgassing; Then you may let it cool to room temperature or somewhat higher and start coating. It will be better if you contact me via my e-mail as I open this site less frequently. For detailed discussion, Reply me at ilatahraf @yahoo. com

Sorry but I really don't see what's the point of suggesting actual numbers for Power, target-to-substrate distance and so on. Power itself is meaningless if you don't know the actual size of the target, geometry of the system and so on,. It would be more useful to know the current density you have on your target while evaporating, for example..

Anyway, as a rule of thumb, if you need to make your film more homogeneous, then follow the previous suggestions regarding your base pressure (i.e. minimize it) and try to play a bit with your deposition pressure (go up to around 1 10-2 mbar). If you have BIAS and/or a heating stage, you can also play with those two parameters in order to really alter your film's microstructure.

Hi Shahinur,

The crystal size and hillocks are really big. To get more information on morphology of sputtered layers please look up the Thornton model where Ts/Tm (=Tsub/Tmelting point) is plotted vs sputter pressure. Looking at that morphology diagram my conclusion is that the pressure you use is ok but I take it that your deposition is done at too high temperatures. Controlling the substrate temperature in vacuum systems is very hard since there is no active cooling and you have hardly conduction of heat from substrate to table. Wehn sputtering substrate temperature can easily achieve a fe hundred degrees. If the glass gets hot during sputtering then as a result of the different CTE's of glass and Al during cooling the Al will contract more than the glass and Al hillocks will form hillocks as a result. The best thing to do is to clamp or glue the glass onto a big ceramic of metal plate so you get more heat capacity and the substrate temperature will stay low. This is the trick which usually works. I don't concur with Mirco that power levels and subtrate distance etc are not important, they are. You need to stay at low pressures to be able to get into the microcrystalline morphology. But low pressures gives more kinetic energy to the neutral Al atoms arriving on the glass and therefore have an impact on the temperature of the substrate (in combination with the powerlevel chosen). So if you stick glass on a heavier substrate and you still see the big grains & hillocks you have to lower the power level as well. Also substratetarget distance in a magnetron really important. DC-magnetron was developed to get an intenser plasma near the target by using magnets. They trap electrons and these become reaaly hot moving over the target surface. If you put a substrateto close to the target it will heat up faster. The cooler part in the plmagnetron asma is away from the target.

regards,

Peter

 Thanks a lot everyone (Farhat Ali, Mirco Chiodi and Peter Knapen), and I will follow your prescribed suggestions.