Cerium oxide target bonded to copper backing plate but sputtered at a power that melted the indium bond and cracked the target
3" diameter Indium tin oxide target sputtered at 1000W (roughly 7x the maximum recommended power)
Aluminum doped zinc oxide target given the 'tough love' treatment of inadequate cooling (at the 10:00 o'clock position) and excessive power
There are many reasons that sputtering targets fail. Some are material specific, while others can be avoided or prolonged by reviewing a few things before sputtering begins.
Maximum Power Density
The amount of power that can be applied varies by material. Visit www.lesker.com sputtering target pages for recommendations on most common materials.
Ramping Power
Some materials require a slow ramp up in power. Applying too much power quickly can cause many materials, especially ceramics and low melting point materials, to fail before deposition can even begin. See our website for a ramping procedure that can be used in these cases.
Bonding
Many materials perform better with bonding. Bonding the target to a backing plate allows for better cooling, adds stability to thin targets, and allows sputtering to continue after minor cracking occurs. Bonding a target will limit the amount of power that can be applied to ~20 watts/square inch. For specifics on which materials are recommended to be bonded, please visit www.lesker.com sputtering target pages prior to ordering.
Low Melting Point
Some materials will actually melt during sputtering. Using very low power and bonding these materials can sometimes make sputtering possible, but there are some cases where sputtering is just not possible.
Sputtering Gun Troubleshooting
When encountering broken targets, if all other parameters seem to be within control, the sputtering gun should be reviewed to ensure that the face of the cathode is within flat. If the cathode is not flat, the target will not be in good contact to provide adequate cooling during sputtering. Though it seems obvious, something as simple as not making sure the cooling water is turned on can cause overheating and failures.
Even when controlling how much power is applied, and how quickly it's applied along with taking bonding into consideration, targets will fail. Targets are considered consumables, but reviewing the parameters above should help extend the lifetime of most sputtering targets.