MICRO-SCRUB PROCESS FOR FLUXLESS MICRO-BUMP BONDING

摘要

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.

主权项

1. A method, comprising:
aligning an array of solder bump structures formed on a bonding surface of a first semiconductor structure to a corresponding array of bonding pads formed on a bonding surface of a second semiconductor structure, wherein the aligning is performed under an applied bonding force so that each solder bump structure is in contact with a corresponding bonding pad; providing an environment around the aligned arrays of solder bump structures and corresponding bonding pads, wherein the environment is adapted to prevent oxides from forming on surfaces of the solder bump structures and corresponding bonding pads; scrubbing the solder bump structures of the first semiconductor structure against the corresponding bonding pads of the second semiconductor structure in a scrubbing direction that is substantially perpendicular to a direction of the applied bonding force, wherein the scrubbing is performed at a given scrubbing frequency and a given scrubbing amplitude and under the applied bonding force; applying heat to the first and second semiconductor structures during the scrubbing so that solder material of each solder bump structure melts and bonds to the corresponding bonding pad; cooling down the first semiconductor structure to solidify the molten solder material of the solder bump structures; and maintaining co-planarity between the bonding surfaces of the first and second semiconductor structures within a given tolerance under the applied bonding force during the scrubbing and cooling steps until solidification of the solder material.