Bridging-resistant microbump structures and methods of forming the same

A bonded assembly comprising a first structure and a second structure that are bonded to each other, wherein:

• the first structure comprises first metallic bump structures;
• the second structure comprises second metallic bump structures;
• each first metallic bump structure within the first metallic bump structures comprises a respective nickel plate portion having a peripheral region that is covered by a passivation dielectric layer and having a center region that underlies a respective opening in the passivation dielectric layer, and has a respective first horizontal bonding surface segment that is vertically recessed away from the second structure from a first horizontal plane including a horizontal dielectric surface of the first structure that is most proximal to the second structure selected from horizontal dielectric surfaces of the first structure;
• each second metallic bump structure within the second metallic bump structures has a respective second horizontal bonding surface segment that protrudes toward the first structure from a second horizontal plane including a horizontal dielectric surface of the second structure that is most proximal to the first structure selected from horizontal dielectric surfaces of the second structure;
• and
• the first metallic bump structures is bonded to the second metallic bump structures through solder material portions.

A method of forming a bonded assembly, the method comprising:

• forming base bump plates on a first structure;
• forming a passivation dielectric layer including openings therein, wherein top surfaces of the base bump plates are physically exposed within the openings;
• providing first metallic bump structures, wherein each first metallic bump structure within the first metallic bump structures comprises a respective one of the base bump plates and comprises a respective first horizontal bonding surface segment that is vertically recessed from a first horizontal plane including a distal horizontal surface of the passivation dielectric layer and located within a respective opening selected from the openings;
• forming second metallic bump structures on a second structure;
• and
• bonding the first metallic bump structures to the second metallic bump structures through solder material portions.