Patent ID: 8090544

Claim:
A method for calculating the concentration of an impurity element included in a primary component substance by Secondary Ion Mass Spectroscopy (SIMS), the method comprising: performing a measurement, including: performing a first measurement (S 1 , S 2 ) that sequentially measures intensities of secondary ions of the primary component substance and the impurity element on the basis of a first measurement condition in which primary ions are irradiated at a first irradiation density during a first measurement period, and performing a second measurement (S 3 , S 4 ) that sequentially measures intensities of secondary ions of the primary component substance and the impurity element on the basis of a second measurement condition in which primary ions are irradiated at a second irradiation density during a second measurement period, such that a total amount of current is identical to that in the first measurement condition; and performing a calculation using a calculation module of a computer, including: performing, using the calculation module, a first calculation (S 5 , S 6 ) that calculates a first dependence that approximates time-lapse variation of the intensities, obtained by the first measurement (S 1 , S 2 ), of the secondary ions of the primary component substance and the impurity element, and a second dependence that approximates time-lapse variation of the intensities, obtained by the second measurement (S 3 , S 4 ), of the secondary ions of the primary component substance and the impurity element, and performing, using the calculation module, a second calculation (S 7 ) that calculates the concentration of the impurity element being independent of elapsed time by using the first dependence and the second dependence.