Conductive Structures, Assemblies Having Vertically-Stacked Memory Cells Over Conductive Structures, and Methods of Forming Conductive Structures

An assembly comprising:

• channel material pillars which extend vertically;
• memory cells along the channel material pillars;
• a conductive structure under the channel material pillars;
• the conductive structure comprising an upper primary portion and one or more conductive projections joined to the upper primary portion and extending downwardly from the upper primary portion;
• the upper primary portion comprising a first conductive constituent and a second conductive constituent;
• the first conductive constituent being configured as a container having a bottom, and having a pair of sidewalls extending upwardly from the bottom;
• an interior region of the container being over the bottom and between the sidewalls;
• the second conductive constituent being configured as a mass filling the interior region of the container;
• the second conductive constituent comprising a different composition than the first conductive constituent;
• the second conductive constituent comprising conductively-doped semiconductor material;
• and
• the channel material pillars being directly against the conductively-doped semiconductor material of the second conductive constituent.