PROJECTION ION-BEAM LITHOGRAPHY

Demagnifying mask-to-wafer projection with ion beams is a potential li thographic technique for high volume device production with large proc ess latitudes. Sub-0.1 mum resolution is possible with more than 10 mu m depth of focus. Furthermore, there is the possibility of an electron ic alignment on-line during chip exposure with nanometer precision: '' pattern lock'' may be achieved in feedback control loops by controllin g X and Y position, rotation, scale, difference in X-Y scale and trape zoidal distortion of the projected ion image by dipole, quadrupole, an d hexapole fields induced in an electrostatic multipole, by axial magn etic fields generated in a solenoid, and by the fine adjustment of len s voltages. Results obtained with an advanced research type ''Alpha Io n Projector'' are presented with the focus on recent exposure latitude evaluations. Further developments of ion projection lithography are d iscussed concentrating on electrostatic lens optics for the realizatio n of large exposure fields (20 X 20 mm2-35X35 mm2) with less than 20 n m distortion. Results of a cost of ownership model for ion projection steppers are presented.