Hello Eeveryone,
I am looking for some references to see the affect of distance between sputter target and sample. I usually keep the distance of about 25 cm but i have heard from some researcher that they keep very close about 5 cm.
My target is in C63 tube, so the plasma is directed toward the sample. I am afraid that plasma will remove the film depositing on sample also.
Whether a TSD is to be considered large or small depends on the rest of the setup. In ion beam deposition with magnetron sputtering it may even go beyond 1m.
In RF sputtering it may be crucial for the survival of the plasma since you can actually "squeeze" your plasma to death if the TSD gets too small. In many cases a larger TSD causes a smaller growth rate which may be desirable for some systems.
The final point is that every sputtering chamber has its characteristic "focus" which means that with a certain power only in a certain TSD range you will get a flat and homogenoous growth.
Dear Aman Baunthiyal ,
Changing the distance between target and substrate may change the characteristic of the atoms arriving at the substrate, thus producing different thin films. For low distance, ballistic atoms dominates (those with high energy and directonality) whereas for large distance the contribution of thermalized atoms is very important (those that have suffered collisions during their travel, and as a result arrive with much lower energy and any direction). You should estimate the thermalization mean free path of your sputtered particles and decide accordingly.
Please check:
Article On the Deposition Rates of Magnetron Sputtered Thin Films at...
We have also investigated the effect of distance between substrate and target (dS-T) on the film characteristics. High quality superconducting thin films of YBCO were obtained, if the substrate was placed just below the negative glow of the discharge (dS-T= 25 mm to 35 mm).
When the substrate was kept at distance from the negative glow region films were found to have a high-Tc, but Jc was quite low. When the substrate-target distance dS-T was less than 25mm the deposited films were found to be non-uniform in thickness and composition. It was probably because for small dS-T the film during growth was also exposed to bombardment with excited neutrals and negatively charged ions, which results in changes in composition of the film due to re-sputtering. It can be seen that the critical temperature Tc(R=0) depends on the substrate-target distance. The critical temperature Tc(R=0) was found to be 88K, 89K, 90K and 91K for the substrate target distance of 32mm, 33mm, 34mm and 35mm respectively.
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