Reducing-Agent Crucible for Preventing Oxide Contamination
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Using, in a vacuum deposition apparatus, a crucible which not only serves as a reducing-agent but also forms volatile wastes, eliminates contaminating films on the surface of the melt and improves process controllability within the apparatus. The figure shows the reaction diagrammatically, with no attempt at quantification. Carbon, made available from a carbon crucible for the melt in an electron-beam evaporator, reacts as a reducing-agent with lead oxide (or with indium oxide), producing metal and gaseous carbon oxides which are easily pumped away. Residual oxygen, otherwise present in the vacuum chamber, would form oxide films on the surface of the melt which might impede deposition rate control or supply oxygen to form unwanted effects, such as diffusion barriers.