Method for manufacturing semiconductor devices

A method for manufacturing semiconductor devices for packaging a semiconductor chip onto a wiring board by a flip-chip approach and then injecting a resin into an under-fill portion between said wiring board and said semiconductor chip, said method comprising steps of:

• a flux-coating step of preparing said semiconductor chip having a right face with ball-like solder electrodes thereon and then coating flux onto said right face of said semiconductor chip;
• a semiconductor-chip packaging step of preparing said wiring board having a right face with eutectic solder bumps thereon;
• mounting said semiconductor chip onto said wiring board in such a way that said ball-like solder electrodes are aligned with said eutectic solder bumps and then melting said eutectic solder bumps to package said semiconductor chip onto said wiring board;
• a flux wash-off step of forcedly sending a washing solution by using a forced water stream method into a narrow region of said under-fill portion between said semiconductor chip and said wiring board, including a minute region between said ball-like solder electrodes to wash off flux remaining in said under-fill position;
• plasma etching to remove any of said flux still remaining in said under-fill portion by exposing said wiring board to a plasma atmosphere portion after said flux wash-off step;
• and
• injecting said resin into said under-fill portion.