[labnetwork] Issue Striking Plasma for NiFe Sputtering on Angstrom Nexdep PVD System – Need Guidance

[Andrey Blednov]

Hello Mohammad,

In order to ignite the plasma on any target, you need to have a
sufficiently strong magnetic field above it. For most materials, this is
not a problem given that the magnet assembly inside the gun is not damaged.
However, ferromagnetic targets typically require special effort to ignite
plasma. You need to "saturate" the target itself and still have a
reasonable field above the target surface. That requires either a thinner
target or stronger magnet assembly (or both).

I didn't work with any of the Nexdep tools but it looks like your gun is
designed (and optimized) for using 2" targets which are normally fairly
thin (<3 mm). That, in turn, very likely means that your 1-mm thick NiFe
target is (a) too thick, (b) too far from the magnet assembly (don't forget
the 3+ mm backing plate). In that case, the power supply would max out on
voltage and have zero current, essentially meaning there's no
plasma/deposition. If you have access to a magnetometer, you can do a quick
test and measure the field above the center of the gun with and without the
target (or using any other target). You can expect to be able to strike
plasma if the field is at least ~100 Gauss, and more is better. If the
field is higher than that (200-300 Gauss or higher) and you still cannot
strike the plasma - try usual tricks like increasing the pressure (10-15-20
mTorr is acceptable, and you can decrease it later once the plasma is lit)
or striking another gun in the same chamber (if you have one) to help
strike the magnetic one, then turn off the "helper gun".

Alternative solutions can be: (1) using a gun with a stronger magnet
assembly, specifically designed for ferromagnetic targets; (2) decreasing,
to the max degree possible, the thickness of the backing plate, effectively
bringing the target closer to the magnets; (3) thinning down the target
itself - depending on your specific gun, you may need to go as thin as
using the foil.

Hope this helps.

Andrey Blednov

пн, 13 окт. 2025 г. в 19:32, Mohammad Mohtasim Hamid Pial <mpial001 at fiu.edu
>:

> Dear All,
>
> I am attempting to deposit NiFe using a magnetron sputtering setup
> (Angstrom Engineering – Nexdep PVD platform). Below are my target
> specifications and sputtering parameters:
>
> Target: NiFe (2" dia × 1 mm, 4N purity) bonded to a 1/8" Cu backing plate
> Sputtering Method: DC Magnetron Sputtering
> DC Power: 100–150 W
> Base Pressure: ~10⁻⁶ Torr
> Ar Gas Flow Rate: 20–30 sccm
> Working Pressure: 3–5 mTorr
>
> However, I am unable to ignite the plasma. The DC power supply setpoint
> keeps blinking and the power stalls around 15 W before dropping
>
> Could this issue be due to insufficient magnetic field strength (not
> penetrating the thick target/Cu backing), or is the target too thick for
> effective plasma ignition? Do I need a thinner target or additional
> magnetic confinement?
>
> I would greatly appreciate any insights or recommendations from anyone who
> has sputtered NiFe or similar high-permeability alloys on this platform.
>
> Thank you in advance!
> Pial
>
>
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