Precursor and process design for photo-assisted metal atomic layer deposition (ALD) and chemical vapor deposition (CVD)
Precursor and process design for photo-assisted metal atomic layer deposition (ALD) and chemical vapor deposition (CVD) is described. In an example, a method of fabricating a thin metal film involves introducing precursor molecules proximate to a surface on or above a substrate, each of the precursor molecules having one or more metal centers surrounded by ligands. The method also involves depositing a metal layer on the surface by dissociating the ligands from the precursor molecules using a photo-assisted process.
1. A method fabricating an interconnect structure for an integrated circuit, the method comprising:
providing a previous layer metallization structure comprising an alternating metal line and dielectric line first grating pattern having a first direction;
forming a dielectric line second grating pattern above the previous layer metallization structure, the dielectric line second grating pattern having a second direction, perpendicular to the first direction;
forming a sacrificial structure above the first grating pattern and between the dielectric lines of the second grating pattern;
replacing portions of the sacrificial structure above and aligned with the metal lines of the first grating pattern with a first dielectric layer, and replacing portions of the sacrificial structure above and aligned with the dielectric lines of the first grating pattern with a second dielectric layer;
forming, by using a photo-assisted process, at least a portion of one or more conductive vias in the first dielectric layer, on a surface of exposed portions of the metal lines of the first grating pattern, wherein using the photo-assisted process comprises:
introducing precursor molecules proximate to the surface of the exposed portions of the metal lines, each of the precursor molecules comprising one or more metal centers surrounded by ligands; and
depositing a metal layer on the surface of the exposed portions of the metal lines by dissociating the ligands from the precursor molecules using photo-dissociation;
recessing portions of the first and second dielectric layers; and
forming a plurality of metal lines in the recessed portions of the first and second dielectric layers, coupled with the one or more conductive vias, the plurality of metal lines having the second direction.
2. The method of claim 1 , wherein dissociating the ligands from the precursor molecules using photo-dissociation comprises using a direct photo-dissociation process involving delivery of photons directly to the precursor molecules.
3. The method of claim 2 , wherein using the direct photo-dissociation comprises irradiating at a first wavelength of light to dissociate a first portion of the ligands and, subsequently, irradiating at a second wavelength of light to dissociate the remaining of the ligands.
4. The method of claim 1 , wherein dissociating the ligands from the precursor molecules using photo-dissociation comprises using an indirect photo-dissociation process involving delivery of photons first to chromophores anchored to the surface of the exposed portions of the metal lines, and then from the chromophores to the precursor molecules.
5. The method of claim 1 , wherein depositing the metal layer on the surface of the exposed portions of the metal lines comprises depositing selectively on the surface of the exposed portions of the metal lines without depositing on an adjacent, different, surfaces.
6. The method of claim 1 , wherein depositing the metal layer on the surface of the exposed portions of the metal lines comprises forming the metal layer to a thickness approximately equal to or less than 3 nanometers.
7. The method of claim 1 , wherein using the photo-assisted process comprises irradiating at a wavelength of light approximately in the range of 150-800 nanometers.
8. The method of claim 1 , wherein depositing the metal layer comprises performing the deposition at a temperature approximately in the range of 25-200 degrees Celsius.