Titanium is rated “excellent” for e-beam evaporation. We recommend using a crucible liner as opposed to running the material directly from the copper hearth. Like with thermal evaporation, intermetallic crucibles work well with titanium due to the crucible liner material’s unique lubricious and conductive properties. Intermetallic crucibles are composed of titanium boride (TiB2) and boron nitride (BN). This material combination works well because the material is both lubricious and electrically conductive. The crucible is both strong and conductive, yet its lubricious properties help prevent material spill-over and crucible cracking. Graphite or FABMATE® crucible liners are available as an alternative to the intermetallic crucible liners. Graphite and FABMATE® liners tend to be less expensive than their intermetallic counterparts. However, we have found that power levels have been more stable with the intermetallic liners. More consistent results are achieved when pre-melting titanium, as the material will wet the crucible allowing for efficient evaporation to take place.
A key process note is to consider the fill volume in the e-beam application because we find that the melt level of a material in a 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. This is the most common cause of crucible liner failure. Placing too little material in the crucible or allowing the melt level to get too low 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.
Crucible liners should be stored in a cool, dry place and always handled with gloves or forceps.
Category: Deposition Materials
Sub-Category: Evaporation Pellets, Pieces and Wire