Methods for enhancing trench capacitance and a trench capacitor so formed
are disclosed. In one embodiment a method includes forming a first
portion of a trench; depositing a dielectric layer in the first portion;
performing a reactive ion etching including a first stage to etch the
dielectric layer and form a micro-mask on a bottom surface of the first
portion of the trench and a second stage to form a second portion of the
trench having a rough sidewall; depositing a node dielectric; and filling
the trench with a conductor. The rough sidewall enhances trench
capacitance without increasing processing complexity or cost.