Hello,

I'm not much of an expert but my hunch would be that due to overheating some
interlock might prevent the system to ignite or sustain the plasma. By venting
and pumping down - the system has enough time to cool down until it heats up
again when the system is running...

regards,

sebastian


-----Ursprüngliche Mitteilung-----
Von: Pramod Gupta 
An: General MEMS discussion 
Verschickt: Do., 1. Okt. 2009, 2:16
Thema: [mems-talk] Plasma Drop in Pre-Clean Chamber

Hi

We have a pre-clean chamber with parallel plate electrodes where 13.56MHz power
supply is connected to substrate table. We are trying to etch SiO2 wafer in this
chamber before taking the wafer to PVD/Sputtering chamber for deposition.

Problem: The plasma extinguishes after few runs, and we can not ignite the
plasma. To ignite the plasma, we have to vent the chamber and pump it down. It
runs OK up to few runs and then plasma drops again and does not ignite until we
vent the chamber and pump it down. By venting and pumping down the chamber, what
exactly is getting changed inside the chamber?

I really appreciate your expert opinion.

With regards,

Pramod Gupta