| 摘要 |
PURPOSE:To restrain an irregularity in the height of a solder bump forming a bump shape and to enhance the strength of the solder bump by a method wherein conductive fillers having a large particle size are mixed with a solder paste, the whole surface of a chip is coated with the solder paste and a heat treatment is executed. CONSTITUTION:An Al pad 2 is formed on a semiconductor substrate 1; a cover film 3 is grown on it by a vapor growth method. Then, a polyimide film 4 is applied to the whole surface of the substrate; a Ti film 5 and a Pd film 6 are applied as barrier metal films. Metal balls which can be eutectic with a solder, e.g. Au or Cu whose particle size is 70 to 100mum, as conductive fillers are mixed with a paste in which an organic acid, a Pd powder and an Sn powder have been diffused into an organic solvent in the ratio of 1:4 to 1:25 in terms of their volume percentage. The whole surface of the substrate is coated with the solder paste 7 with which the fillers have been mixed; a heat treatment is executed to the substrate at 200 to 320 deg.C for several minutes. Thereby, a solder alloy bump 7A is formed selectively only the barrier metal film. At this time, the conductive fillers act as a role to form the framework of the bump, and the height of the bump becomes uniform. |
