| 摘要 |
PROBLEM TO BE SOLVED: To analyze concentration of metallic impurities at high sensitivity without producing a large quantity of residue by employing an acid solution containing hydrofluoric acid and nitric acid at a specific ratio at the time of decomposing a semiconductor thin film or substrate. SOLUTION: A silicon semiconductor substrate 301 is immersed into a mixture solution 302 of hydrofluoric acid and nitric acid in beaker 303 and decomposed. The decomposition solution containing dissolved metallic impurities 304 is then concentrated. When the concentration is continued furthermore the decomposition solution is dried and solidified to leave a residue 305. The residue 305 is dissolved again with pure water 306 to prepare a sample for analysis. Subsequently, the silicon substrate is decomposed with a mixture solution of hydrofluoric acid and nitric acid having mixing ratio in the range of 0.3-0.6. When the decomposition solution is concentrated thermally, the residue composed of diammonium hexafluoro silicate itself is reduced thus realizing high sensitivity analysis of metallic impurities. Finally, the sample is analyzed. |
