US 12,685,052 B2Granted

Low pressure plasma etch process for preferential generation of oxide residue and applications for the same

AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.

InventorsTzu-Ging Lin, Jih-Jse Lin

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Abstract

A semiconductor structure may be provided by: forming semiconductor fins over a semiconductor substrate; forming a gate dielectric layer and gate electrodes; forming a silicon layer over the gate electrodes; forming a dielectric mask layer including openings over the silicon layer; etching portions of the silicon layer that underlie the openings by performing a first anisotropic etch process; etching portions of the gate electrodes that underlie the openings by performing a second anisotropic etch process; and removing portions of the semiconductor fins and portions of the semiconductor substrate that underlie the openings by performing a third anisotropic etch process. At least one anisotropic etch step within the third anisotropic etch process comprises at least one low pressure etch step that is performed at a total pressure in a range from 5 mTorr to 50 mTorr.

Claims20

Dependent claims

A method of forming a semiconductor structure, comprising:

forming semiconductor fins over a semiconductor substrate;
forming a gate dielectric layer over the semiconductor fins;
forming gate electrodes over the gate dielectric layer;
forming a silicon layer over the gate electrodes;
forming a dielectric mask layer including openings over the silicon layer;
etching portions of the silicon layer that underlie the openings in the dielectric mask layer by performing a first anisotropic etch process;
etching portions of the gate electrodes that underlie the openings in the dielectric mask layer by performing a second anisotropic etch process;
and
removing portions of the semiconductor fins and portions of the semiconductor substrate that underlie the openings in the dielectric mask layer are removed by performing a third anisotropic etch process that uses a plasma of a gas mixture comprising hydrogen bromide gas, and wherein:
at least one anisotropic etch step within the third anisotropic etch process comprises at least one low pressure etch step that is performed at a total pressure in a range from 5 mTorr to 50 mTorr;
and
during the at least one low pressure etch step, the gas mixture comprises oxygen gas, and a ratio of a flow rate of the oxygen gas to a flow rate of the hydrogen bromide gas is in a range from 0.2 to 0.5.

9 more elements

A method of forming a semiconductor structure, comprising:

forming semiconductor fins over a semiconductor substrate;
forming a silicon layer over the semiconductor fins;
forming discrete openings through the silicon layer;
forming a dielectric mask layer over the silicon layer, wherein the dielectric mask layer comprises dielectric pillar portions that fill the discrete openings;
forming an opening through the dielectric mask layer;
forming a via cavity by etching portions of the silicon layer that underlie the opening through the dielectric mask layer, wherein sidewalls of a pair of the dielectric pillar portions are physically exposed to the via cavity;
and
performing an anisotropic etch process that etches portions of the semiconductor fins and portions of the semiconductor substrate that underlie the via cavity, wherein the anisotropic etch process comprises at least one low pressure etch step using a plasma of a gas mixture comprising hydrogen bromide gas at a total pressure in a range from 5 mTorr to 50 mTorr.

5 more elements

Dependencies are inferred from the claim text.