| 摘要 |
A semiconductor read-only memory (ROM) has trenches and vertical transistors. The trenches are filled with insulator material during the manufacturing process. Holes, which are as wide as the trenches are etched into the insulator at regions where word lines and decoder lines are to be provided over the trenches in a later manufacturing step. In a subsequent masking process for changing the conductivity characteristic of channel regions of transistors, channel regions selected according to programming requirements, are doped. The insulator remaining in the trenches prevents that regions under the insulator material are affected by the masking method.
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