Bonded assembly including interconnect-level bonding pads and methods of forming the same

A method of forming a bonded assembly, comprising:

• forming a first semiconductor die, wherein the first semiconductor die comprises first semiconductor devices, first interconnect-level dielectric material layers embedding first metal interconnect structures, and first metallic bonding structures embedded within a first bonding-level dielectric layer, wherein one of the first metallic bonding structures comprises:
• first tapered sidewalls that are laterally spaced apart along a first horizontal direction, laterally extending along a second horizontal direction, and having a first taper angle with respect to a vertical direction;
• and
• second tapered sidewalls that are laterally spaced apart along the first horizontal direction, laterally extending along the second horizontal direction, having top edges located within a horizontal plane including bottom edges of the first tapered sidewalls, and having a second taper angle with respect to the vertical direction,
• and wherein the second taper angle is greater than the first taper angle at by least a factor of 3, and is in a range from 25 degrees to 55 degrees;
• providing a second semiconductor die, the second semiconductor die comprising second semiconductor devices, second interconnect-level dielectric material layers embedding second metal interconnect structures, and second metallic bonding structures embedded within a second;
• and
• bonding the second metallic bonding structures to the first metallic bonding structures.