| 摘要 |
PURPOSE:To make it easy to desides the exchange of a semiconductor device for a new device by a method wherein a structure of rectifying contact or a MIS capacitor is prepared in the neighborhood of the device in the semiconductor substrate constituting the semiconductor device, and the increment of threshold voltage of device is estimated from the quantity of electric charge flowing into a depletion layer belonging to this structure. CONSTITUTION:Reverse conducting type regions 21, 22 are prepared in a one-conducting type semiconductor substrate, and an electrode 3 is fitted up putting insultating films between them to form a MOS type transistor. The region 21 is connected to the earth, a power source 5 is connected to the electrode 3 and to the region 3 and to the region 22 respectively and the transistor action is made to be performed. In this constitution, another p-n junction structure is prepared in the same substrate in the neighborhood of the transistor to be monitored about deterioration, and the reverse biasing power source 5 is connected to it through an ammeter 4. By this way, if the avalanche phenomenon takes place during the operation of the transistor, plural holes flow into a depletion layer under the structure 25, so that the phenomenon can be detected instantaneously by the ammeter 4. |
