Three-dimensional memory structure with multi-component contact via structure and method of making thereof
A contact via structure can include a ruthenium portion formed by selective deposition of ruthenium on a semiconductor surface at the bottom of a contact trench. The ruthenium-containing portion can reduce contact resistance at the interface with an underlying doped semiconductor region. At least one conductive material portion can be formed in the remaining volume of the contact trench to form a contact via structure. Alternatively or additionally, a contact via structure can include a tensile stress-generating portion and a conductive material portion. In case the contact via structure is formed through an alternating stack of insulating layers and electrically conductive layers that include a compressive stress-generating material, the tensile stress-generating portion can at least partially cancel the compressive stress generated by the electrically conductive layers. The conductive material portion of the contact via structure can include a metallic material or a doped semiconductor material.
1. A structure comprising:
an alternating stack of insulating layers and electrically conductive layers located over a substrate;
an insulating spacer located at a periphery of a contact trench that extends through the alternating stack; and
a contact via structure laterally surrounded by the insulating spacer and comprising:
a ruthenium-containing portion contacting a top surface of a doped semiconductor portion located in or over the substrate; and
at least one conductive material portion overlying the ruthenium-containing portion and located within an inner sidewall of the insulating spacer.
2. The structure of claim 1 , wherein the at least one conductive material portion comprises:
a metallic diffusion barrier layer contacting a top surface of the ruthenium-containing portion and the inner sidewall of the insulating spacer; and
a conductive fill material portion surrounded by the metallic diffusion barrier layer.
3. The structure of claim 2 , wherein:
the metallic diffusion barrier layer comprises a material selected from a conductive metallic nitride material and a conductive metallic carbide material;
the electrically conductive layers comprise a compressive stress-generating material; and
the conductive fill material portion comprises a tensile stress-generating metal.
4. The structure of claim 2 , wherein:
the metallic diffusion barrier layer comprises a conductive metallic nitride material;
the electrically conductive layers comprise tungsten; and
the conductive fill material portion comprises cobalt.
5. The structure of claim 3 , wherein the at least one conductive material portion comprises another portion including a metallic material different from the tensile stress-generating material.
6. The structure of claim 1 , wherein:
the ruthenium-containing portion has a uniform thickness throughout, and consists essentially of elemental ruthenium; and
the doped semiconductor portion is a source region of a three-dimensional memory device.
7. The structure of claim 1 , further comprising at least one memory stack structure extending through the alternating stack, wherein each of the at least one memory stack structure comprises, from inside to outside:
a semiconductor channel;
a tunneling dielectric laterally surrounding the semiconductor channel; and
charge storage regions laterally surrounding the tunneling dielectric layer, and wherein:
the structure comprises a three-dimensional memory device that comprises a vertical NAND device formed in a device region;
the electrically conductive layers comprise, or are electrically connected to, a respective word line of the NAND device;
the device region comprises:
a plurality of semiconductor channels, wherein at least one end portion of each of the plurality of semiconductor channels extends substantially perpendicular to a top surface of the substrate;
a plurality of charge storage regions, each charge storage region located adjacent to a respective one of the plurality of semiconductor channels; and
a plurality of control gate electrodes having a strip shape extending substantially parallel to the top surface of the substrate;
the plurality of control gate electrodes comprise at least a first control gate electrode located in a first device level and a second control gate electrode located in a second device level;
the electrically conductive layers in the alternating stack are in electrical contact with the plurality of control gate electrodes and extend from the device region to a contact region including a plurality of electrically conductive via connections; and
the substrate comprises a silicon substrate containing a driver circuit for the NAND device.
8. A method of manufacturing a structure, comprising:
forming an alternating stack comprising insulating layers and electrically conductive layers over a substrate having a trench extending through the alternating stack;
forming an insulating spacer on a sidewall of the trench;
forming a ruthenium-containing portion on a top surface of a doped semiconductor portion located in or over the substrate and underlying the trench;
forming at least one conductive material portion on the ruthenium-containing portion within an unfilled volume of the trench, wherein a combination of the ruthenium-containing portion and the at least one conductive material portion constitutes a contact via structure.
9. The method of claim 8 , wherein:
the ruthenium-containing portion is formed by selective deposition of ruthenium on the doped semiconductor surface while ruthenium is not deposited on the insulating spacer; and
the at least one conductive material portion is formed directly on an inner sidewall of the insulating spacer.
10. The method of claim 8 , wherein the at least one conductive material portion is formed by:
forming a metallic diffusion barrier layer on a top surface of the ruthenium-containing portion and on an inner sidewall of the insulating spacer by depositing a material selected from a conductive metallic nitride material and a conductive metallic carbide material; and
forming a conductive fill material portion by depositing cobalt or fluorine free tungsten inside the metallic diffusion barrier layer.
11. The method of claim 10 , wherein:
the electrically conductive layers are formed by depositing a compressive stress-generating material; and
the conductive fill material portion is formed by depositing a tensile stress-generating material.
12. The method of claim 11 , wherein:
the electrically conductive layers are formed by depositing tungsten; and
the conductive fill material portion is formed by depositing cobalt.
13. The structure of claim 8 , further comprising forming at least one memory stack structure extending through the alternating stack, wherein each of the at least one memory stack structure comprises, from inside to outside:
a semiconductor channel;
a tunneling dielectric laterally surrounding the semiconductor channel; and
charge storage regions laterally surrounding the tunneling dielectric layer, and wherein:
the structure comprises a three-dimensional memory device that comprises a vertical NAND device formed in a device region;
the electrically conductive layers comprise, or are electrically connected to, a respective word line of the NAND device;
the device region comprises:
a plurality of semiconductor channels, wherein at least one end portion of each of the plurality of semiconductor channels extends substantially perpendicular to a top surface of the substrate;
a plurality of charge storage regions, each charge storage region located adjacent to a respective one of the plurality of semiconductor channels; and
a plurality of control gate electrodes having a strip shape extending substantially parallel to the top surface of the substrate;
the plurality of control gate electrodes comprise at least a first control gate electrode located in a first device level and a second control gate electrode located in a second device level;
the electrically conductive layers in the alternating stack are in electrical contact with the plurality of control gate electrodes and extend from the device region to a contact region including a plurality of electrically conductive via connections; and
the substrate comprises a silicon substrate containing a driver circuit for the NAND device.