Investigation of fabrication uniformity and emission reliability of silicon field emitters for use in space

A silicon field emitter neutralizer is under development at the Rutherford Appleton Laboratory for the LISA Pathfinder mission [B.J. Kent, Class Quantum Grav. 22, S483 (2005)]. A summary of this project from the fabrication point of view is presented in this article. An investigation of the effect of fabrication uniformity on emission characteristics showed that the geometrical nonuniformity, including tip height and gate diameter, across a 4-in. wafer is below 15%. This variation had only a small effect (∼10%) on the field-emission characteristics. In order to improve the reliability of the silicon field emitters for the space environment operation, a thin aluminum nitride (AlN) film is coated on the silicon emitters, and the chromium gate electrode is oxidized in furnace. The effects of adding the layer of AlN and thermal oxidation of the chromium gate electrode on field emission and lifetime were investigated in this article. A fabrication yield analysis estimated that 50% of arrays on the original wafer functioned correctly in the final device, but that this can be substantially improved by a more rigorous device handling control. © 2006 American Vacuum Society