Method to thermally form hemispherical grain (HSG) silicon to enhance capacitance for application in high density DRAMS

摘要

An embodiment of the present discloses a thermal process for forming hemispherical grained silicon on a silicon material by the steps of: heating the silicon material to a steady state temperature; exposing the silicon material to a hydrogen containing ambient; and causing a decreasing temperature differential of the silicon material while exposing the silicon material to a silicon hydride gas. This embodiment is accomplished by using a thermal cycle having a temperature ramp up period, a temperature steady state period during at least a portion of which the H.sub.2 ambient is present and temperature ramp down period during at least a portion of which the diluted silicon hydride gas is present. A second embodiment discloses a process for forming a hemispherical grained silicon surface on at least one capacitor plate made of silicon material, by increasing the temperature of the capacitor plate in an H.sub.2 containing ambient; exposing a surface of the capacitor plate's silicon material to a cleaning gas (such as GeH.sub.4, NF.sub.3, using ultraviolet light in the presence of ozone gas, vapor hydrofluoric acid silicon hydride gas, and H.sub.2); and decreasing the temperature of the capacitor plate while exposing the capacitor plate to a silicon hydride gas.