| abstract |
A soft error occurs due to the influence of alpha rays from the material in the vicinity of a semiconductor chip, and therefore, there is a need for a material with high purity and low alpha rays, especially for solder materials used in the vicinity of semiconductor devices. It has been. Then, while clarifying the phenomenon of α-ray generation in bismuth, provision of a high-purity bismuth with reduced α dose of bismuth and its manufacturing method, an alloy of bismuth and tin with low α-ray and a manufacturing method thereof. SOLUTION: Bismuth with an α dose of 0.5 cph / cm 2 or less is used as a raw material, and the raw material bismuth is dissolved in a nitric acid solution by electrolysis, so that the bismuth concentration is 5 to 50 g / L and the pH is 0.0 to 0.4. A bismuth nitrate solution is prepared, and this solution is passed through a column packed with an ion exchange resin. The polonium in the solution is exchanged and removed with the ion exchange resin, and the solution after passing through the ion exchange resin is electrolyzed and collected. The production method of low alpha ray bismuth whose alpha dose which collects is 0.003 cph / cm <2> or less. [Selection] Figure 2 |