Fast Bit Screening of Automotive Grade EEPROMs—Continuous Improvement Exercise

This paper presents the optimization of an existing electrically eraseable programmable read-only memory (EEPROM) production test flow by means of thorough analysis of the faulty dice and the test flow, which leads to an increase in the yield, a significant decrease in test time, and a decrease in the dppm (increase in quality) level leaving the factory. In order to manufacture high quality and cost-effective EEPROMs suitable for automotive underhood applications, several topics must be taken into account. In addition to a high reliability EEPROM technology, the choice of an advanced memory architecture including error correction code and a highly sophisticated screening methodology in production test is necessary to achieve high quality in the field. The EEPROM production test flow must not only be able to screen out weaknesses in the process but must also be cost efficient. A majority of the tests executed in the EEPROM test flow are needed to check the quality of the processed oxides, which are the basic elements to realize the EEPROM function of the memory. Most of these tests are complex and time-consuming.