Methods for bonding semiconductor structures involving annealing processes, and bonded semiconductor structures and intermediate structures formed using such methods

A method of bonding a first semiconductor structure to a second semiconductor structure, comprising:

• depositing metal over a first semiconductor structure;
• removing a portion of the metal deposited over the first semiconductor structure prior to subjecting the metal deposited over the first semiconductor structure to any annealing process;
• subjecting a remaining portion of the metal deposited over the first semiconductor structure to a first thermal budget and annealing the remaining portion of the metal deposited over the first semiconductor structure by subjecting the remaining portion of the metal to a first average annealing temperature over a first annealing time period;
• removing an additional portion of the metal deposited over the first semiconductor structure after annealing the remaining portion of the metal deposited over the first semiconductor structure;
• directly bonding at least one metal feature of the first semiconductor structure comprising a remaining portion of the metal deposited over the first semiconductor structure to at least one metal feature of a second semiconductor structure to form a bonded metal structure comprising the at least one metal feature of the first semiconductor structure and the at least one metal feature of the second semiconductor structure;
• and
• subjecting the bonded metal structure to a second thermal budget and annealing the bonded metal structure by subjecting the bonded metal structure to a second average annealing temperature over a second annealing time period, the second thermal budget being less than or equal to the first thermal budget.