Using effective wet etching technology to improve deep trench shape

For trench type DRAM the trench surface in the depth direction of the capacitor without expanding the capacitor size is a good method to fit the specification of the charge storage. This paper reports a wet etching technology for modifying trench shape of the DRAM capacitor to enhance effective capacitance surface area. The ammonium hydroxide-water based wet etching solution was preferred over other etchants in our study experiments. The tested samples dipped in about 0.57 wt.% NH₄OH then rinsed by H₂O in sequence showed that excellent shape modification of the DRAM capacitor deep trench can be achieved.