Patent attributes
A fluxless bonding process is provided. An array of micro solder bumps of a first semiconductor structure is aligned to an array of bonding pads of a second semiconductor structure under an applied bonding force. An environment is provided to prevent oxides from forming on the solder bump structures and bonding pads during the bonding process. A scrubbing process is performed at a given scrubbing frequency and amplitude to scrub the micro solder bumps against the bonding pads in a direction perpendicular to the bonding. Heat is applied to at least the first semiconductor structure to melt and bond the micro solder bumps to the bonding pads. The first semiconductor structure is cooled down to solidify the molten solder. Coplanarity is maintained between the bonding surfaces of the semiconductor structures within a given tolerance during the scrubbing and cooling steps until solidification of the micro solder bumps.
