PURPOSE: To shorten the testing time by reading out the test result stored in a memory when there is a bad memory in a memory array and then eliminating unnecessary tests.
CONSTITUTION: For good products which are judged no problem or remediable by remedy judgement in a pretest, a flag which shows that they are good products is written. For the good products, a pretest is finished by writing the flag (12, 14). Writing of the flag is selected only at a test mode with a redundant bit which is constituted of a programable and non-volatile semiconductor memory cell. A flag which shows a test result of the pretest is read out from the redundant bit and only the chips which are judged good can proceed to the next step (23, 21, 22A). In a function test (22A), test items which overlap those in the pretest are eliminated. In a wafer test, the result of the pretest can be known instantly and therefore the testing time for bad products can be shortened.
SHIMAZAKI MASAMITSU
OKUGAKI AKIRA
