| 摘要 |
The method of forming buried contacts on a semiconductor substrate is as follows. At first, a gate insulator layer is formed over the substrate. A first silicon layer is then formed over. A buried contact opening is defined through the first silicon layer and the gate insulator layer extending down to the substrate. The substrate is then doped for forming a buried contact region. Next, a second silicon layer and a masking layer is formed. A shielding opening is then defined through the masking layer and the second silicon layer to a portion of the buried contact region. At the same time, an upper gate electrode and an interconnect are defined by removing a portion of the second silicon layer. A shielding layer is formed in the shielding opening over the buried contact region. A lower gate electrode is then defined by removing a portion of the first silicon layer. Following the removal of the masking layer, the substrate is doped for forming a second doping region under a region uncovered by the upper gate electrode, the interconnect, and the shielding layer. A sidewall structure is then formed on the sidewall of the upper gate electrode and the lower gate electrode. The substrate is doped for forming a third doping region in the second doping region under a region uncovered by the sidewall structure. Finally, a thermal process is performed to finish the formation of the trench-free buried contact.
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