METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device in which voids formed in solder bumps after fusion are suppressed while keeping excellent connectivity between the solder bumps.SOLUTION: A first substrate 2 with a first solder bump 1 and a second substrate 4 with a second solder bump 3 are arranged in a furnace after they are stacked while the solder bumps 1 and 3 are temporarily fixed to each other. A carboxylic acid gas is introduced after the furnace is exhausted to produce a pressure-reduced atmosphere. While the temperature in the furnace after the introduction of the carboxylic acid gas is raised, the furnace is exhausted within a temperature range equal to or higher than a reduction temperature of an oxide film by the carboxylic acid gas and lower than a fusion temperature of the solder bumps 1 and 3 to produce a pressure-reduced atmosphere. The temperature in the furnace is raised up to a temperature range equal to or higher than the fusion temperature of the solder bumps 1 and 3, which are fused for joining.