| 摘要 |
<p>A semiconductor memory device includes a circuit (20) for generating a voltage stress mode signal on the basis of a predetermined signal input through some of external terminals used in a normal operation of a DRAM circuit (10), and a control circuit (21) for receiving the test mode signal from the circuit (20) and performing control such that upper bits, of an output signal from a refresh address counter (4), which are more significant than a specific bit are fixed at the same level, and lower bit less significant than the specific bit are subjected to a normal count operation. When an AC voltage stress test mode in which a high voltage is applied to word lines at a high duty ratio is to be set for a DRAM in a wafer state or a packaged state, no special voltage stress test pads are required, thus reducing an increase in chip area. In addition, any failure modes which can occur in a normal operation but are difficult to predict, such as a decrease in breakdown voltage between adjacent word lines or adjacent bit lines, can be simultaneously screened. The device further includes a control circuit (21) for receiving the test mode signal from the circuit (20) and performing control such that all the bits of an output signal from the refresh address counter (4) are fixed at the same level so as to cause a word line driving circuit (8) to simultaneously drive all the word lines. In setting a desired DC voltage stress mode for a DRAM in a wafer state or a packaged state, no special voltage stress test pads are required, and the number of circuits other than the circuit required for the normal operation mode can be minimized, thereby reducing an increase in chip area. <IMAGE></p> |
