Projection ion lithography with aperture lenses

Abstract

This paper reports on experiments in projection ion lithography in which multiple demagnified images have been etched directly into a substrate through an aperture lens array, without using a resist or proximity mask. The ion source is an 8-cm-beam-diam, Kaufman-type mercury ion thruster, which accelerates ions through a grid of perforated plates, and then neutralizes the resultant beamlets by injecting electrons at ground potential. The neutralized ion beam is allowed to pass through a suitable mask and thence onto an array of apertures of a few tens of microns in diameter. Ions impinging on the apertures are accelerated through a field produced by imposing a negative potential on a substrate placed just downstream of the aperture array. An image of the mask is etched in the substrate directly below each aperture. The substrate is a polished metal disk which has been sputter coated with a number of alternating layers of chromium and copper, each about 500 Å thick. Etching of these layers quickly produces an easily visible contour map which accurately depicts variations in the etch rate over the substrate surface. It is necessary to generate random motion of the substrate relative to the ion source to prevent projection of a superimposed image of the ion source grid system. To date, mask elements of the order of 2–3 mm in diameter have been used to produce multiple images demagnified by about 20–30× with resolution better than 10 μm. Suitable equipment is now being fabricated to permit exploration of the submicron region.

The science of ceramic machining and surface finishing II

“…85. We see that for larger, more irregular cracks (where the assumption of the theory that the diameter of the crack is less than 1/4 wavelength is not well satisfied), the error between theory and experiment increases.…”

“…68, 80, 99, 109, 112, 192, 200, 251/t 398, 498-500. efficiency, 202 forces, 62,65,68,78,85,86,99 hardness, 66 530 SUBJECT INDEX (continued) models, 1,71,103,191 rates, 42,192,[204][205][206]216 The proceedings contain forty of forty-three research papers, together with floor discussions, presented at the Symposium. Specific topics covered include: L) mechanisms of abrasive machining and surface finishing; 2) technology of machining md surface finishing; 3) characterization of machined surfaces; and 4) effects of machining on the properties of ceramics.…”

“…At a concentration of 10~2 Mol/litre, only one group of tests was made, at the beginning of the experiment, immediately after re-sharpening. There is a fairly rapid fall from 85 to near 65 Figure 15. Granite: rate of penetration as a function of distance drilled using water or various concentrations of CWS liquid soap as flushing liquids.…”

“…7). The latter method allows multiple images to be projected [85] at up to fifty times demagnif ication [86] so that very small patterns may be machined.…”