Methods for testing unprogrammed OTP memory

摘要

Methods for testing unprogrammed single transistor and two transistor anti-fuse memory cells include testing for connections of the cells to a bitline by comparing a voltage characteristic of a bitline connected to the cell under test to a reference bitline having a predetermined voltage characteristic. Some methods can use test cells having an access transistor identically configured to the access transistor of a normal memory cell, but omitting the anti-fuse device found in the normal memory cell, for testing the presence of a connection of the normal memory cell to the bitline. Such a test cell can be used in a further test for determining the level of capacitive coupling of the wordline voltage to the bitlines relative to that of a normal memory cell under test.

主权项

1. A method for testing an unprogrammed one-time-programmable (OTP) memory cell, comprising:
precharging a first bitline and a second bitline to a first voltage; activating a normal memory cell connected to the first bitline; coupling a second voltage to the first bitline and the second bitline; comparing a voltage characteristic of the first bitline to a predetermined voltage characteristic of the second bitline after the second voltage is coupled to the first bitline and the second bitline; and, determining if the normal memory cell is defective in response to the comparing of the voltage characteristic of the first bitline to the predetermined voltage characteristic of the second bitline.