Method for improving yield and reading reliability of electrically erasable programmable read-only memory (EEPROM)

Abstract

The invention discloses a method for improving the yield and the reading reliability of an electrically erasable programmable read-only memory (EEPROM). In the method, a value of a reference unit current is set by determining a reference unit current region, so that translation of the value of the reference unit current is realized, the problem that a large number of EEPROM units fail during test due to a fixed value of the reference unit current can be solved, and the test yield is improved; meanwhile, by the method, a few of failed EEPROM units can be screened out through steps of testing the '1' state of the EEPROM by selecting a minimum value of the reference unit current region and testing the '0' state of the EEPROM by selecting a maximum value of the reference unit current region; therefore, a detection allowance for reading the '1' state and the '0' state of the EEPROM can be retained; and the reading reliability of the delivered EEPROM is improved.

Description

technical field [0001] The invention relates to the field of EEPROM detection, in particular to a method for improving EEPROM yield and reading reliability. Background technique [0002] In the existing non-volatile memory, EEPROM is widely used because of its bit-based operation, long data retention time, and many times of erasing and writing, and is especially suitable for occasions that require frequent information updates and high reliability. The process of EEPROM production is relatively complicated, and the control difficulty is relatively large. In fact, in different positions of the same wafer or even the same chip, no matter how the process is controlled, its various parameters will have slight changes and show a normal distribution. For any single chip, if there is even a single EEPROM cell failure, then the chip is a waste product. This requires reasonable design and screening to overcome changes in parameters within a certain range so that it will not affect t...

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Problems solved by technology

[0004] In fact, due to the leakage current of the EEPROM device itself, when the EEPROM cell stores "1", there may be a leakage current in the branch where the EERPOM cell is located, especially the leakage current of individual cells may affect the correctness of the read value; and in When the EEPROM cell stores "0", due to the unevenness of the process, the threshold voltage varies, and the correctness of reading the "0" value of individual cells may also be affected.

In this way, if the reference cell current is simply set to the middle value of the EEPROM cell current corresponding to "0" and "1", it may affect the EEPROM yield and read reliability.

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