[labnetwork] Striking plasma on WO3 in Lesker PVD 75 issue

[Martin, Michael]

Hi Tucson,
   When we use metal targets we check that the target and the dark space shroud are electrically isolated with a meter.  This is obviously impractical with a dielectric target but what can happen is that the shroud can short to the target ring.  You can use a nice pointy meter probe to contact the target ring and look for a short to the shroud. Also, you might consider simply increasing the space between shroud and target.  On our PVD75 there are several notches in the shroud to set this spacing.
   If you are confident that there is no short then one trick I use regularly is to set the RF power to 50 - 100 W, then turn on the substrate etch with the shutter closed at 100W (the max).  This usually works to get the target plasma going.  Then turn off the substrate etch and turn your target power to a low power, something like 10-20W.  You will want to ramp this power up slowly (maybe 0.5W/sec or so) to your endpoint so that the target heats slowly.  Dielectric targets are notorious for cracking.  One other consideration is to make sure that the target ring is NOT super tight on the target.
   We do not usually put anything between the target and electrode.

Regards,
   Michael

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Sent: Friday, August 9, 2024 4:59 PM
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Subject: [labnetwork] Striking plasma on WO3 in Lesker PVD 75 issue

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Hello,



I have a Lesker PVD 75. It was working fine last week with a TiO2 target. This week I swapped out the target for WO3 and suddenly the plasma won’t strike.



Normal Operating Conditions:

Turbo                    30% speed

Pressure               50mTorr of Argon

Power                   50 W



I tried putting the TiO2 target back and it wouldn’t strike either.

Usually I cut a circle of copper fabric and place it between the target and the sputter gun. That has worked for the past year. Usually when the plasma won’t strike, I need to replace the copper fabric. I tried that and it didn’t work.

Then I put some silver paste on the target and used the copper fabric and it worked! TiO2 had plasma strike.

I switched back to WO3, and used silver paste and copper fabric, but it won’t strike.



Here’s what I’ve tried:

Turbo                    20, 30%

Pressure               15, 50, 60, 70, 95mTorr of Argon

Power                   50, 60, 70 W



Any suggestions? What do you normally put between the target and the sputter gun?







Best,

Tucson Richelson

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