| 摘要 |
PURPOSE:To measure the film thickness of a film which absorbs light of less than micrometers by deciding whether or not the absolute value of the difference between the film thickness of a sample and rough film thickness is larger than a specific value, calculating the film thickness again when so and making a decision as mentioned above, and repeating the measuring and decision making operation until the difference becomes less than the specific value. CONSTITUTION:Reflectivity of respective wavelengths are found in a step 1 and rough film thickness d0 is found from two maximum wavelengths lambda1 and lambda2 of R. This d0 is used to calculate film thickness newly in a step 3 on condition that the film thickness is thin. When the difference between the newly calculated (d) and d0 is larger than requested measurement precision DELTAd, the (d) is substituted with the d0 and film thickness is calculated again. Consequently, the measured film thickness approximates to the real film thickness (d) gradually. Namely, a decision is made in a step 4 to make a return to before the film thickness calculation when NO and outputs the film thickness (d) in a step 5 when YES.
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