Method of enhancing protection of dielectrics from plasma induced damages and equipment
AssigneeSTMicroelectronics S.r.l.
InventorFederico Pio
Life of this patent
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Abstract
During critical plasma etching steps, the wafer's surface is illuminated with electromagnetic radiation in the visible and/or in the UV spectrum having an energy and power density sufficient to increase the reverse current through protective junctions on the wafer. These protective junctions provide electrical discharge paths for electrical charges picked up by exposed conductive parts of the wafer. The induced voltages are limited to values compatible with preserving the integrity of functional dielectric layers coupled to the exposed conductive parts and to the semiconductor substrate or to another conductive part.
Claims14
A method for fabricating a semiconductor device comprising the steps of:
- forming at least one diffused region in a semiconductor substrate;
- depositing at least one dielectric layer and at least one conductive layer stacked on the at least one diffused region;
- patterning by masking and etching the at least one dielectric layer and the at least one conductive layer, at least one of the depositing and etching steps being carried out in a plasma by placing the semiconductor substrate on a wafer support defining an electrode that is biased in gases ionized at a sub-atmospheric pressure with respect to another electrode;
- forming protective junctions in the semiconductor substrate functionally connected to conductive portions of the at least one conductive layer exposed to the plasma for providing electrical discharge paths for electrical charges picked up by the exposed conductive portions to limit a level of induced voltages to preserve the integrity of the at least one dielectric layer coupled;
- and
- illuminating a surface of the semiconductor substrate during the at least one plasma step with electromagnetic radiation to enhance a reverse current through the protective junctions.
A method for protecting a dielectric layer in a semiconductor device comprising at least one conductive layer on the dielectric layer, and at least one protective junction connected to conductive portions of the at least one conductive layer exposed to a plasma, the method comprising the step of:
- illuminating a surface of the semiconductor device during exposure to the plasma with electromagnetic radiation to enhance a reverse current through the at least one protective junction.
Dependencies are inferred from the claim text.