Ramp Procedure for Ceramic Target Conditioning
- Attempting to ignite a plasma at low power may require a high argon gas pressure. Typically, 5E-2 Torr (6.7 Pa) is required for low power ignition. Once the plasma has stabilized, the pressure can be reduced to that normally used for sputtering the particular target material.
- Power to the target should be ramped up slowly through the break-in period. The rate of increase should be limited to 10 - 20 watts per minute. If the target material's properties and its response to the application of power are in doubt, choose the lower power ramp value. If arcing, voltage spikes, or other plasma irregularities occur during ramp up, stop ramping power and allow the plasma to stabilize before starting the ramp again.
- Since the deposition rate increases as the power density increases, the natural tendency is to use high power to speed up deposition. However, each particular target mounted in a particular sputter source will have its own heat transfer characteristics. Applying a higher power density than is acceptable results in the target overheating and subsequently fracturing and/or bond failure (if the target is bonded).
- When the deposition run is complete, it is equally important to ramp-down power at the same rate as the ramp-up, allowing the target to cool slowly to avoid thermal shock and the potential for target fracture. As an added precaution, allow the chamber to cool slowly to ambient temperature before venting.
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