| 摘要 |
In a non-volatile semiconductor memory device, a top surface of a floating gate that is made of polysilicon is advantageously kept smooth to increase the uniformity of an overlying interpoly dielectric layer onto which a control gate is formed. The floating gate is doped after at least a portion of the overlying interpoly dielectric layer has been formed. Ion implantation techniques are employed to implant dopants through the overlying layer or layers and into the floating gate. Consequently, the potential for polysilicon grain growth at or near the top surface of the floating gate, which can lead to significant depressions in the overlying layers and data retention problems in the memory cell, is substantially reduced.
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