| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor substrate where the operation characteristic of a semiconductor product in a wafer state can highly precisely be measured under the condition approximate to the installation atmosphere condition of whole operation characteristic regulation factors. SOLUTION: A ring oscillator 1 formed on a wafer performs an oscillation operation under the condition approximate to the installation atmosphere condition of whole operation characteristic regulation factors affecting the operation characteristic such as a wiring factor by pattern wiring, a gate factor by a gate element and the process factor of the dispersion of a process in the wafer apart from various factors regulating current Ids between the source and drain of a transistor. An oscillation signal F1 from the ring oscillator 1 is frequency- divided so that it is not affected by the measurement precision of a tester 10 by a frequency divider 2, and the delay timeτof an obtained test signal Fo is measured. Thus, the speed yield of a semiconductor memory in the wafer state can highly precisely be predicted without the influence of the measurement precision of the tester 10 in the atmosphere condition approximate to an actual operation state.
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