PURPOSE: To make a decision on the quality of a semiconductor element with high precision by writing a binary-coded characteristic pattern, drawn on the screen of a curve tracer, into a memory circuit as a bit pattern and then by comparing it with the output of an expected-value generating circuit.
CONSTITUTION: A characteristic pattern drawn on the screen of CRT5 of curve tracer 1 is converted by photoelectric converter 7 into an electric signal, which is coded by binary coding circuit 8 and then written as a bit pattern in memory circuit 10 whose addresses correspond to coordinates of the screen. To set a limit value, the output of memory circuit 10 is inputted to decision circuit 12 together with the output of expected-value generating circuit 11 where a bit pattern of constant width is pre-written, thereby making a decision on quality. Therefore, since the characteristic pattern is detected by several dot patterns, slight distortion of characteristics and variation in characteristics can be detected, sod that a defect due to aging variation can also be detected.
ONO HIROTAKA
KIMURA KAZUHIKO
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