CHEMICAL ETCHING OF LaB6-CATHODES
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Implementation of Critical Koehler Illumination (C.K.I.) in E-beam lithography tools requires LaB6-cathodes with outstanding surface quality. Disclosed is a fabrication technique for such cathodes. The ideal LaB6-cathode for C.K.I. is a perfect single crystal confined in size and shape by crystal planes of high symmetry (represented by low indices) defining a truncated pyramid (frustrum). The present technique utilizes a single crystal LaB6-cathode already shaped as a truncated cone by means of conventional grinding techniques. The size of the flat top, the cone angle and the crystal orientation are crucial parameters determining size and shape of the cathode after treatment. Crucial process parameters are cathode temperature Tc, reactor gas pressure p and ionization voltage vi .