| 摘要 |
PROBLEM TO BE SOLVED: To readily and in approximation compute interface state density on the interface of an SOI(silicon-on-insulator) thin-film and an insulating layer, in an SOI substrate, even when impurity concentration in the SOI thin-film cannot be obtained accurately. SOLUTION: The interface state density on the interface of an SOI thin-film 14 and an insulating layer 13 in an SOI substrate 10 is computed by means of a pseudo-MOSFET, on the basis of the formula Dit=(|Vth-V0|-A)×(Cox/q) (In the formula, Dit represents interface state density, Vth the gate voltage at strong inversion start, V0 the gate voltage when a depletion layer reached the surface of an SOI thin-film 14, Cox the capacitance per the unit area of the insulating layer 13, (q) element charges and A are a constant correction value computed by the ceiling value of impurity concentration in the SOI thin- film 14 and the film thickness of the SOI thin-film 14). Here, when P-type or N-type impurity concentration in the SOI thin-film 14 is 1×1014-1×1017 atoms/cm3 and the film thickness of the SOI thin-film 14 is at a value from 30 nm to 300 nm, it is desirable that the correction value (A) take a fixed value within a range of -0.1 to 0.8.
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