Method for increasing the capacitance in a storage trench and trench capacitor having increased capacitance

Abstract

In a method for forming a trench capacitor a first layer of silicon oxide is deposited in a storage trench and a layer of silicon is deposited over the first layer by a chemical vapor deposition process. A layer of an oxidizable metal is deposited over the layer of silicon. The layer of silicon and the layer of the oxidizable metal are subsequently oxidized to form a layer of silicon oxide and metal oxide.

We claim:  
     
         1 . A method for increasing a capacitance in a storage trench, which comprises the steps of: 
 depositing a layer of silicon oxide in the storage trench;    depositing a layer of silicon over the layer of silicon oxide by a deposition method suitable for sufficient coverage of walls of the storage trench;    depositing a layer having an oxidizable metal over the layer of silicon; and    oxidizing the layer of silicon and the layer having the oxidizable metal to form a layer having a metal oxide and an silicon oxide.    
     
     
         2 . The method according to    claim 1   , which comprises using one of a chemical vapor deposition process and an atomic layer deposition process as the deposition method.  
     
     
         3 . The method according to    claim 2   , which comprises depositing a further layer formed of a material selected from the group consisting of silicon oxide and silicon nitride over the layer having the metal oxide and the silicon oxide.  
     
     
         4 . The method according to    claim 1   , which comprises using a metal selected from the group consisting of Ti, TiN, W, WN, Ta, TaN, Wsi, TiSi and TaSi as the oxidizable metal of the layer having the oxidizable metal.  
     
     
         5 . The method according to    claim 1   , which comprises carrying out the oxidizing step in an oxygen-containing atmosphere.  
     
     
         6 . The method according to    claim 1   , which comprises filling the storage trench with silicon.  
     
     
         7 . The method according to    claim 1   , which comprises forming the storage trench to have a width of less than  140  nm.  
     
     
         8 . The method according to    claim 1   , which comprises forming the layer of silicon oxide to have a thickness of approximately 0.3 nm.  
     
     
         9 . The method according to    claim 3   , which comprise which comprises forming the further layer to have a thickness of approximately 0.3 nm.  
     
     
         10 . The method according to    claim 3   , which comprises depositing the layer of silicon oxide and the further layer by a chemical vapor deposition process.  
     
     
         11 . The method according to    claim 1   , which comprises forming the layer of silicon to have a thickness of approximately 0.5 nm.  
     
     
         12 . The method according to    claim 1   , which comprises using silicon in the layer of silicon which is particularly suitable for covering side walls of the storage trench.  
     
     
         13 . The method according to    claim 1   , which comprises forming the layer having the oxidizable metal to a thickness of approximately 10 nm.  
     
     
         14 . The method according to    claim 1   , which comprises depositing the layer having the oxidizable metal by a chemical vapor deposition process.  
     
     
         15 . A trench capacitor having an increased capacitance, comprising: 
 a substrate having a storage trench formed therein and said storage trench defined by side walls and a bottom;    a first layer of silicon oxide covering said side walls and said bottom of said storage trench;    a layer having a metal oxide covering said first layer of silicon oxide;    a second layer of silicon oxide covering said layer having said metal oxide; and    silicon filling in a remainder of the storage trench.    
     
     
         16 . The trench capacitor having the increased capacitance according to    claim 15   , wherein said metal oxide is selected from the group consisting of Ti, TiN, W, WN, Ta, TaN, Wsi, TiSi and TaSi.