Contact vias in semiconductor devices
AssigneeAmerican Telephone and Telegraph Company, AT&T Bell Laboratories
InventorsRoland A. Levy, Kurt Nassau
Life of this patent
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Abstract
A glass reflow step to round off sharp edges of contact vias is typically included in processes for making integrated-circuit devices. In the course of making such devices with closely spaced vias, it has been found that unacceptable overhangs occur on the sidewalls of the vias. Neither changes in the composition of the glass nor modifications in the processing parameters of reflow were effective to avoid the overhang phenomenon. In accordance with the invention, it has been discovered that the overhang problem can be consistently avoided if the ratio of glass thickness to via-to-via spacing is about .ltoreq.0.393.
Claims6
A microminiature device comprising
- a dielectric layer made of a reflowable mateiral,
- spaced-apart vias in said layer, said vias having no overhangs therein at equilibrium after reflow, the smallest spacing s between vias being approximately.ltoreq.1.75 .mu.m,
- wherein t is the maximum thickness of any of the walls defining said vias in said layer,
- and wherein t/s is approximately .ltoreq.0.393.
Dependencies are inferred from the claim text.