Replacement control gate methods and apparatuses

Abstract

Disclosed are memory structures and methods for forming such structures. An example method forms a vertical string of memory cells by forming an opening in interleaved tiers of dielectric tier material and nitride tier material, forming a charge storage material over sidewalls of the opening and recesses in the opening to form respective charge storage structures within the recesses. Subsequently, and separate from the formation of the floating gate structures, at least a portion of the remaining nitride tier material is removed to produce control gate recesses, each adjacent a respective charge storage structure. A control gate is formed in each control gate recess, and the control gate is separated from the charge storage structure by a dielectric structure. In some examples, these dielectric structures are also formed separately from the charge storage structures.

What is claimed is: 
     
         1 . An apparatus comprising:
 a memory array including,
 multiple tiers of dielectric material vertically offset from one another; 
 multiple tiers of barrier material interleaved with the multiple tiers of dielectric material and also vertically offset from one another, each barrier material tier including charge storage structures, and further including control gates, each control gate adjacent a respective charge storage structure; 
 wherein each control gate is separated from an adjacent charge storage structure by an associated multi-component dielectric structure, and 
 wherein each control gate and associated multi-component dielectric structure has a vertical dimension which is greater than the vertical dimension of the adjacent charge storage structure. 
   
     
     
         2 . The apparatus of  claim 1 , wherein the vertical dimension of each control gate and associated dielectric structure is greater than the vertical dimension of the barrier tier in which it is formed. 
     
     
         3 . The apparatus of  claim 2 , wherein the control gates comprise at least one of a polysilicon and a metal. 
     
     
         4 . The apparatus of  claim 3 , wherein the control gates comprise a metal liner material substantially surrounding a control gate material. 
     
     
         5 . The apparatus of  claim 4 , wherein the metal liner material comprises titanium nitride (TiN), tungsten nitride, or tantalum nitride. 
     
     
         6 . The apparatus of  claim 1 , wherein the control gates comprise tungsten or polysilicon.