Ernst Hammel

Ion Beam Lithography

Abstract Ion beam lithography (IBL) is still in the hands of researchers. The immediate aim is to investigate the production of micro-circuits with 0.1 μm line spacings in commercial prototypes. However such instruments can also be used for mask repair. The present paper, intended as an introduction to the more specialised contributions to IBL in these Proceedings, concentrates on basic physical principles. While ion sources of different types are covered, particular attention is paid to liquid metal ion sources, in view of their popularity and potential for a variety of applications in focused ion beam technology.Apparatus and method for projection ion beam lithography are described which allow formation of low distortion, large field, reduced images of a mask pattern at a wafer plane using an optical column of practical size. The column shown is comprised of an accelerating Einzel lens followed by a gap lens, with numerous cooperating features. By coordinated selection of the parameters of the optical column, lens distortion and chromatic blurring are simultaneously minimized. Real time measurement of the position of the image field with respect to the existing pattern on the wafer is employed before and during the time of exposure of the new field and means are provided to match the new field to the existing pattern even when the latter has been distorted by processing. A metrology system enables convenient calibration and adjustment of the apparatus.

Ion projection lithography in (in)organic resist layers

Abstract Ion Projection Lithography (IPL) was applied for structuring organic and inorganic resists. To prove the feasibility of Ion Projection Lithography for printing submicron features the pattern transfer characteristics was determined in PMMA and SiO 2 resist layers. Furthermore, Response Surface Methodology (RSM) was used to evaluate the dependence of the obtained results on various process parameters. By application of RSM the machine setup was optimized and process latitudes were established.