Browse Prior Art Database

Self-Correction of Inter-Chip E-Beam Proximity Effect

IP.com Disclosure Number: IPCOM000102018D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Quickle, RJ: AUTHOR [+2]

Abstract

This method improves the proximity correction of chip designs exposed with E-beam direct write lithography tools. Current postprocessors neglect the contribution of adjacent exposed chips when correcting for the E-beam proximity effect. This method provides a way of approximating adjacent chips' contribution to the proximity effect.

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Self-Correction of Inter-Chip E-Beam Proximity Effect

       This method improves the proximity correction of chip
designs exposed with E-beam direct write lithography tools. Current
postprocessors neglect the contribution of adjacent exposed chips
when correcting for the E-beam proximity effect.  This method
provides a way of approximating adjacent chips' contribution to the
proximity effect.

      The proximity effect causes exposure of regions of the resist
not directly addressed by the E-beam tool, due to electron scattering
in the target.  Current E-beam postprocessors compensate for the
proximity effect by varying the doses assigned to individual shapes
based upon their size and distance to other shapes.  Proximity
correction is performed for each layer of a chip design based solely
upon the shapes contained entirely within that design layer.  The
proximity correction does not account for the effect of the exposure
of neighboring chip designs.  In actual exposures of wafers, each
chip design will be adjacent to one to eight other chips designs.
Since shapes in a chip design may be at minimum allowed distance from
shapes in the neighboring chips, the exposure of the neighboring
chips influences the exposure of the original chip design through the
proximity effect.  This is particularly true for wafers exposed with
high accelerating voltages, where the proximity backscatter distance
is as great as 15 uM, depending upon the resist system and substrate
used.  Compare this backscatter distance to the minimum separation of
1 - 2 uM in advanced chip designs.

      This method approximates the contribution of adjacent chips by
proximity, correcting the chip design as if it were its own neighbor
in all directions (see the...