| 摘要 |
A semiconductor read-only memory (ROM) and a method of fabricating the same are provided. The ROM device is structured in such a manner that allows the fabrication to include a fewer number of mask processes. This makes it more cost effective and allows a cycle time that is shorter than that of the prior art. Moreover, the particular structure of the ROM device makes punchthrough less likely to occur between any neighboring pairs of the buried bit lines when the ROM device is further scaled down. The ROM device is constructed on a semiconductor substrate which is partitioned into a peripheral region and a cell region. A plurality of STI structures are formed at predefined locations in both the peripheral region and the cell region. Immediately after this, a first ion-implantation process can be performed on the cell region to form a plurality of buried bit lines. Subsequently, the dielectric isolation layers in all of the STI structures in the cell region are removed, leaving a plurality of empty trenches behind. A conformal insulating layer and a conductive layer are then successively formed over the wafer, and the conductive layer is further selectively removed to form a word line in the cell region and a gate in the peripheral region. In the code implantation process, selected channel regions between the buried bit lines are doped with impurities for code implantation of data into the ROM device.
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