The study of deep trench etch process for PCRAM

The deep trench (DT) is the key process to form the diode array in the diode-selected Phase Change Random Access Memory (PCRAM). In this work, the DT has been successfully developed with common etch chamber. We investigated the influence of different etch schemes on the DT profile. It is demonstrated Si etch with hard mask scheme can deliver better DT profile than that with soft mask. The gas impact on the DT profile is also studied. Bowing free profile is got after F-based gas decrease and necking profile is much improved with N2 gas decrease. At last the correlation between Si damage and DT profile is also showed.

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