A method of forming a bonded assembly includes providing a first semiconductor die containing and first metallic bonding structures and a first dielectric capping layer containing openings and contacting distal horizontal surfaces of the first metallic bonding structures, providing a second semiconductor die containing second metallic bonding structures, disposing the second semiconductor die in contact with the first semiconductor die, and annealing the second semiconductor die in contact with the first semiconductor die such that a metallic material of at least one of the first metallic bonding structures and the second metallic bonding structures expands to fill the openings in the first dielectric capping layer to bond at least a first subset of the first metallic bonding structures to at least a first subset of the second metallic bonding structures.