Lithography with high depth of focus by an ion projection system

It is reported that ion projection lithography has been developed to generate structures with minimum feature sizes in the 100-nm range with a high pixel transfer rate. The high depth-of-focus resulting from the telecentric beam path concept is noted. A silicon wafer exhibiting 200-μm-deep cavities, which were fabricated by anisotropic etching, was patterned with a grating of 0.6-μm periodicity running with identical spacings from the bottom to the top. SiO₂ served as an inorganic ion sensitive resist. Exposed to 73 keV helium ions, the SiO₂ showed an enhanced etching rate in hydrofluoric acid, the structure developing agent. The application of patterning techniques considered is thought to be promising for the fabrication of two-dimensional reflecting mirrors or sensoric elements distributed on spherical surfaces