FABMATE® is the only crucible liner material recommended for e-beam evaporation of nickel. However, it is limited to only one run. During evaporation, the nickel will melt and adhere to the crucible liner walls. Upon cooling and reheating (if it makes it that far), the difference in thermal contraction and expansion of the nickel and the FABMATE® liner will cause immense stress on the liner, and it will crack. Experienced users are sometimes able to get multiple runs out of a FABMATE® liner with slow ramp rates of ~0.1% power/sec both up and down.
A key process note is to consider the fill volume of the crucible liner. We find that the melt level of a material in the crucible directly affects the success of the crucible liner. Overfilling the crucible will cause the material to spill over and create an electrical short between the liner and the hearth. The outcome is cracking in the crucible liner. This is the most common cause of crucible liner failure. Placing too little material in the liner or evaporating too much material before refilling can be detrimental to the process as well. When the melt level is below 30%, the e-beam is likely to strike the bottom or walls of the crucible which immediately results in breakage. Our recommendation is to fill the crucible between ⅔ and ¾ full to prevent these difficulties. However, even when following these fill guidelines, the FABMATE® liner will fail during cooling. Crucible liners should be stored in a cool, dry place and always handled with gloves or forceps.
Nickel can also be run directly from the copper hearth of the e-gun. Because of this, some customers prefer to use a pre-machined slug (or starter source) that is directly placed in the hearth pocket. The two main benefits of using a starter source are ease of use and handling as well as superior packing density. In order to avoid broken crucible liners, we have had customers install starter sources directly in the hearth.
Because not using a crucible liner is not always an option, especially in shared systems, some customers will use a copper crucible liner and place the starter source in the copper crucible liner instead of placing directly in the hearth.
KJLC® can produce these starter sources. Contact sales@lesker.com with your e-gun manufacturer, pocket size, and number of pockets in order for us to produce a quote.
Category: Evaporation Sources
Sub-Category: Crucible Liners for E-Beam Sources
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