| 摘要 |
<p>PURPOSE:To eliminate previously a defective mode in an unwritten state by using two rows of test cells in addition to a normal memory cell array to obtain a pattern with which a parasitic PNP effect is easily produced. CONSTITUTION:Two row lines X1' and X2' are used for test purpose in addition to row lines to form a test array of (2 rows Xm columns). Then base open PNP transistors Q'22, Q'24... of an unwritten memory cell, base-collector junction diodes D12, D14..., D21, D23..., etc. of an unwritten memory cell are distributed at intersecting points of row and column lines including a complete open state so that an abnormal current sneaks easily by an NPN effect and that the generation of said abnormal current is easily detected. Then a function test is carried out to confirm a writing defect due to the sneak current. Then this writing defect is eliminated. Thus it is possible to eliminate previously the writing defect due to a current sneaking in an unwritten state.</p> |
