| 摘要 |
A semiconductor read-only memory (ROM) device is provided. The particular semiconductor structure of this ROM device can reduce the parasitic capacitance between the bit lines and the word lines, such that the resistance-capacitance time constant of the memory cells can be reduced to thereby speed up the access time to the memory cells. The binary data stored in each memory cell is dependent on whether a contact window is predefined to be formed in a thick insulating layer between the buried bit lines and the overlaying word lines. If the gate electrode of one memory cell is electrically connected to the associated word line via one contact window through the insulating layer, that memory cell is set to a permanently-ON state representing a first binary value; otherwise, that memory cell is set to a permanently-OFF state representing a second binary value. The threshold voltage of the permanently-ON memory cells is about in the range from 0.4 V to 0.7 V.
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