Global Planarization Characteristics of Shallow Trench Isolation-Chemical Mechanical Polishing Process with and without Reverse Moat Etch Step

The reverse moat etch process has been used for the shallow trench isolation (STI)-CMP process with conventional low selectivity slurries between SiO$_2$ and Si$_3$N$_4$ film. The process became more complex, and the defects seriously increased. Because the removal rates of each region were different in the STI-CMP process, damage might occur on active regions in case of an excessive CMP process, whereas, in the case of an insufficient CMP process, some nitride might remain on the active region after nitride strip process due to unpolished oxide residues. In this paper, we investigated the CMP characteristics of STI structure with a reverse moat step. Then, we studied the direct STI-CMP process without reverse moat etch step using high selectivity slurry (HSS). As our experimental results, it was possible to achieve good global planarization characteristics without the complicated reverse moat process, and therefore the STI-CMP process could be simplified and greatly improved. KCI Citation Count: 11