| 摘要 |
A method for forming a Trench Mask ROM cell comprises the steps of: Providing a substrate doped lightly with p-type dopant; forming plural trenches and then, forming a gate layer on each trench, further, implanting n+-type ions on substrate beneath the gate oxide layer on bottom of each trench and position between each two adjacent trench; and then, forming a nitride layer on the gate oxide layer; forming an oxide layer on the nitride layer and each trench being filled with the oxide layer; and removing the oxide layer and the nitride layer of partial trenches, namely, partial trenches reserving the oxide and the nitride layer to define coding regions of the Trench Mask ROM cell; finally, depositing a polysilicon layer on the top surfaces of the substrate wherein the polysilicon being word line of the Trench Mask ROM cell.
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