Method of forming a dram cell having a ring-type stacked capacitor

摘要

A new method for fabricating a storage capacitor, on a dynamic random access memory (DRAM) cell, having a ring-type sidewall was accomplished. The method involves opening the self-aligned node contact to the source/drain area of the field effect transistor and forming the bottom capacitor electrode. The same photoresist mask used to open the self-aligned node contact is later used to mask and partially etch the polysilicon bottom capacitor electrode to form the ring-type sidewall on the bottom electrode. The storage capacitor is then completed by forming a thin capacitor dielectric and depositing the top electrode. The method provides a simple process that increases the capacitance of the storage capacitor by about 40 percent while not adversely affecting the leakage current.