Bonded assemblies and methods for forming the same using polymer-based hybrid bonding

A method of forming a bonded assembly, comprising:

• providing a first memory die including a first alternating stack of first insulating layers and first electrically conductive layers, first memory stack structures vertically extending through the first alternating stack, first metal interconnect structures embedded within first memory-die inorganic dielectric layers, and first memory-die copper bonding pads contacting a respective one of the first metal interconnect structures and embedded within a first polymer dielectric layer;
• providing a second memory die including a second alternating stack of second insulating layers and second electrically conductive layers, second memory stack structures vertically extending through the second alternating stack, second metal interconnect structures embedded within second memory-die inorganic dielectric layers, and second memory-die copper bonding pads contacting a respective one of the second metal interconnect structures and embedded within a second polymer dielectric layer;
• and
• providing the first memory die and the second memory die into a bonded assembly.