| 摘要 |
PURPOSE:To obtain an accurate method with high reliability by measuring the interval between two impurity regions from the measurement of a capacity. CONSTITUTION:A bias voltage VJ is applied between an n-type semiconductor substrate 1 and p-type impurity regions 2, 2', thereby measuring a capacity C therebetween. When depletion layers 3, 3' sufficiently approach due to the increase of a reverse bias voltage VJ, the resistance Rch of the part interposed between the depletions layers becomes high, the side capacity CS cannot be measured, and the measured capacity C eventually becomes only the bottom capacity CB. Accordingly, since the thicknesses of the depletion layers 3, 3' increases together the increase of the reverse bias voltage VJ, the capacity gradually decreases, but abruptly decreases at the certain point. The bias of the point of starting the decrease is a pinch-off voltage VP. In case that the variation in the parallel resistance is measured upon change of the capacity and the parallel resistance exhibits the minimum value in the vicinity when the capacity abruptly varies, it is understood that the abrupt change of the capacity is not mere measuring error nor abrupt change point of the impurity density, but is the point corresponding to the pinch-off. In this manner, since no error exists in the detection of the pinch-off voltage VP due to the measurement of the capacity, the reliability of the measurement can be enhanced. |
