A novel structure, the phosphorus-implanted poly-Si films treated with phosphoric acid (H3PO4) and cleaned by standard RCA cleanup procedures, has been demonstrated as the bottom electrodes of DRAMs' stacked capacitors. After the H3PO4 treatment and RCA cleaning process, micro-island structures are formed on the poly-Si surface of the storage electrodes. The NH4OH + H2O2 + H2O (SC-1) solution in the RCA cleaning procedures is the main component to change the porous surfaces and engraved structures, formed by H3PO4 treatment, into micro-islands. Although the electrical properties are slightly degraded compared to the control samples, but they fulfill the requirements of high-density DRAMs, resulting from the increment of cell capacitance.
- High-density Drams' capacitors
- Poly-Si electrodes
- RCA clean-up procedures