Floating gate and fabrication method therefor

Abstract

A floating gate with multiple tips and a fabrication method thereof. A semiconductor substrate is provided, on which a patterned hard mask layer is formed, wherein the patterned hard mask layer has an opening. A gate dielectric layer and a first conducting layer with a first predetermined thickness are formed on the bottom of the opening. A spacer is formed on the sidewall of the opening. A conducting spacer is formed on the sidewall of the spacer. The first conducting layer is etched to a second predetermined thickness. A multi-tip floating gate is provided by the first conducting layer and the conducting spacer. A protecting layer is formed in the opening. The patterned hard mask layer, the gate dielectric layer, a portion of the protecting layer, and a portion of the first spacer are etched to expose the surface of the first conducting layer.

1 - 19 . (canceled)  
   
   
       20 . A floating gate, comprising: 
 a conductive base, wherein a top edge of the conductive base is tip-shaped; and    a conductive crescent-shaped protruding layer aligned with the tip-shaped structure, wherein a bottom portion of the conductive protruding layer is narrower than the conductive base, and a multi-tip floating gate is provided by the conductive base and the conductive protruding layer.    
   
   
       21 . The floating gate of  claim 20 , wherein the conductive base is a poly layer.  
   
   
       22 . The floating gate of  claim 20 , wherein the conductive protruding layer is a poly layer.  
   
   
       23 . A floating gate, comprising: 
 a conductive base, wherein a top edge of the conductive base is tip-shaped, the conductive base has a first sidewall and a second sidewall, the first sidewall parallel to the second sidewall; and    a conductive protruding layer having a crescent-shaped structure, wherein the crescent-shaped structure is aligned with the tip-shaped structure, a bottom portion of the conductive protruding layer is connected to a top portion of the conductive base, the bottom portion of the conductive protruding layer is narrower than the conductive base, and a multi-tip floating gate is provided by the conductive base and the conductive protruding layer.    
   
   
       24 . The floating gate of  claim 23 , wherein the conductive base is a poly layer.  
   
   
       25 . The floating gate of  claim 23 , wherein the conductive protruding layer is a poly layer.