I would like to deposit film of Yttrium iron garnet using magnetron sputtering technique.
Will there be any problem during deposition??
Any risk to the system??
Dear Arrindam, It's all about getting a stable plasma (which does not extinguish if an arc arises) and the deposition rate which you want to achieve. For both, you need a magnetic stray field (measured about 1 mm above the target surface) and in a direction perpendicular to the racetrack of min. 200 Gauss and by preference some 400 Gauss. Measure it with a Gauss meter ! If you work borderline and the plasma extinguishes, one trick is to rise the deposition pressure (ideally you work at 2-4E-03 mbar in DC, but you could raise to some 6-8E-03 mbar if you get instability in DC). For RF, pressures can be much higher.
Hi,
as long as you do not use a magnet stronger than the magnets into the sputtering cathode (or you don't rise too much the temperature of the cathode) there will be no damage to the magnetron.
Instead, the deposition rate may be affected and results lower if your target is made of a magnetic material.
As well, DC rate is expected to be lower than RF rate for dielectric targets.
Best of Luck!
There is no such problem and there is already a lot of work is done using RF magnetron sputtering. Read the attached articles to get more about deposition parameters.
We do sputtering of pure iron 2 inch diameter, 0.1 mm- thick, DC or RF without any problem. With nickel we could go up to 1 mm. The magnetron magnetic field passing through target must be sufficiently high to initiate the plasma at low pressure. In the worst case, the magnetic field lines do not cross the target and your end up with diode sputtering (plasma could only be operated at high pressure).
You can sputter at lower pressure while sustaining the plasma and definitely a higher growth rate, probably better quality of film.@@
Dear Arrindam, It's all about getting a stable plasma (which does not extinguish if an arc arises) and the deposition rate which you want to achieve. For both, you need a magnetic stray field (measured about 1 mm above the target surface) and in a direction perpendicular to the racetrack of min. 200 Gauss and by preference some 400 Gauss. Measure it with a Gauss meter ! If you work borderline and the plasma extinguishes, one trick is to rise the deposition pressure (ideally you work at 2-4E-03 mbar in DC, but you could raise to some 6-8E-03 mbar if you get instability in DC). For RF, pressures can be much higher.
The sputter rate will be higher at a magnetic pole and less where the magnetic field is in the direction of the target surface unless the magnetic field produces a "race track"m, other than that I do not see a problem.
Actually, John, the sputter yield and rate (erosion rate) is highest in between the magnet poles, where the magnetic field is parallel to the target surface. Because of magnetic and electric fields parallel to each other (perpendicular to the target surface), the target erosion rate is very low above the poles.
As additional comment, I suggest to you to use power regulation, instead of current or voltage regulation.
Power regulation, even if it not often recommended, is very useful in case of sputtering thin magnetic material:
For thin target, the relative erosion from one to another is very high compare to thick target (>0.5mm). Such erosion considerably modify the target voltage and the target current (due to change of magnetic field).
By keeping a constant current, as you erode the target, you will have a higher magnetic field, higher ionization, and increase of the current. Finally, you will have higher deposition rate.
By keeping a constant voltage, you keep the same number of species impacting the target, but with stronger magnetic field as you erode the target, you will have an increase of the voltage, resulting in higher deposition rate (due to lower species thermalisation).
The choice of power regulation give you a compromise between these two effects, and you should get much reproducible coatings, otherwise, you should observe a derive of your conditions. I've observed this during my PhD after many deposition of lanthanum/iron oxide.
The effect of the modification of the impact angle is negligible, due to very low thickness of the target.
Regards,
Emile
We are depositing YIG thin films by rf sputtering. Our target is 3 mm thick. The magnetic field on top of the YIG target is more than 1000 Gauss and it is working nicely.
According to my knowledge, there is no problem for magnetic material in RF/DC magnetron sputtering system, only the deposition conditions (power, pressure) can be different.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science