1. Field of the Invention
The present invention relates to a semiconductor memory device, and more particularly, to a semiconductor memory device having sequentially disabling activated word lines.
2. Description of the Related Art
When a semiconductor memory device is manufactured, the semiconductor memory device undergoes a burn-in stress test and a function test. The burn-in stress test ensures that the semiconductor memory device works under prescribed stress conditions, such as a boosted voltage applied to the semiconductor memory device. The function test is for testing whether the semiconductor memory device operates normally according to a predetermined product specification.
Generally, a method of simultaneously activating a plurality of word lines or sequentially activating a plurality of word lines is used to reduce the time required for the burn-in stress test or the function test. Then, the plurality of activated word lines are simultaneously disabled after the activation of the plurality of word lines. When the plurality of activated word lines are simultaneously disabled, precharge noise is generated during a process where the plurality of word lines are transited from a high level to a low level. The precharge noise can have a critical influence on operations of the semiconductor memory device.
Therefore, a need exists for a semiconductor memory device having function of sequentially disabling the activated word lines to prevent the precharge noise from occurring at the time of disabling the activated word lines.