a method for manufacturing the lower electrode of a dram capacitor . the method includes depositing polysilicon instead of amorphous silicon to form the lower electrode . because polysilicon has a higher depositing temperature , it has a higher depositing rate capable of shortening depositing time . after forming the polysilicon lower electrode , the upper portion of the polysilicon layer is transformed into an amorphous layer by bombarding the polysilicon layer with ions to damage its internal structure . eventually , hemispherical grain silicon is able to grow over the lower electrode , thereby increasing its surface area .