Doped silicon structure with impression image on opposing roughened surfaces

摘要

A silicon structure is formed that includes a free-standing wall having opposing roughen ed inner and outer surfaces using ion implantation and an unplanted silicon etching process which is selective to implanted silicon. In general, the method provides a recess in a layer of insulating material into which a polysilicon layer is formed. A layer of HSG or CSG polysilicon is subsequently formed on the polysilicon layer, after which ions are implanted into both the layer of HSG or CSG polysilicon and the underlying polysilicon layer. The aforementioned selective etching process is then conducted to result in a relatively unplanted portion being etched away and a highly implanted portion being left standing to form the free-standing wall. The free-standing wall has an inner surface that is roughen ed by the layer of HSG or CSG polysilicon. The free-standing wall also has a roughen ed outer surface to which has been transferred a near-impression image topography of the opposing inner surface.