Liquid etchant composition, and etching process in capacitor process of dram using the same

Abstract

An etching process in a capacitor process for DRAM is described. A substrate is provided, which has thereon a silicon layer and metal electrodes in the silicon layer. The silicon layer is removed using a liquid etchant composition. The liquid etchant composition contains tetramethylammonium hydroxide (TMAH), an additive including hydroxylamine or a metal corrosion inhibitor, and water as a solvent.

What is claimed is: 
     
         1 . An etching process in a capacitor process of DRAM, comprising:
 providing a substrate that has thereon a silicon layer and a plurality of metal electrodes in the silicon layer; and   removing the silicon layer using a liquid etchant composition comprising:
 a main etchant consisting of tetramethylammonium hydroxide (TMAH), consisting of NH 4 OH, or consisting of TMAH and NH 4 OH; 
 an additive comprising hydroxylamine or a metal corrosion inhibitor; and 
 water as a solvent. 
   
     
     
         2 . The etching process of  claim 1 , wherein the additive comprises hydroxylamine in an amount within a range of 0.3-0.7 wt % relative to a total weight of the etchant liquid composition. 
     
     
         3 . The etching process of  claim 2 , wherein the main etchant consists of TMAH, and the anisotropic etching is conducted at a temperature within a range of 65-85° C. 
     
     
         4 . The etching process of  claim 2 , wherein the main etchant consists of NH 4 OH, and the anisotropic etching is conducted at a temperature within a range of 50-70° C. 
     
     
         5 . The etching process of  claim 1 , wherein the at least one additive comprises the metal corrosion inhibitor in an amount within a range of 1 to 5 wt % relative to a total weight of the etchant liquid composition. 
     
     
         6 . The etching process of  claim 5 , wherein the main etchant consists of TMAH, and the anisotropic etching is conducted at a temperature within a range of 65-85° C. 
     
     
         7 . The etching process of  claim 5 , wherein the main etchant consists of NH 4 OH, and the anisotropic etching is conducted at a temperature within a range of 50-70° C. 
     
     
         8 . The etching process of  claim 1 , wherein an amount of TMAH is within a range of 4.5-5.5 wt % relative to a total weight of the etchant liquid composition. 
     
     
         9 . The etching process of  claim 1 , wherein the metal electrodes comprise TiN, and the metal corrosion inhibitor comprises a TiN corrosion inhibitor. 
     
     
         10 . The etching process of  claim 9 , wherein the TiN corrosion inhibitor comprises at least one compound selected from the group consisting of diprotic carboxylic acids and phenolic compounds. 
     
     
         11 . The etching process of  claim 1 , wherein the silicon layer comprises poly-Si. 
     
     
         12 . A liquid etchant composition for etching silicon, comprising:
 a main etchant consisting of tetramethylammonium hydroxide (TMAH), consisting of NH 4 OH, or consisting of TMAH and NH 4 OH;   an additive comprising hydroxylamine or a metal corrosion inhibitor; and   water as a solvent.   
     
     
         13 . The liquid etchant composition of  claim 12 , wherein the additive comprises hydroxylamine in an amount within a range of 0.3-0.7 wt % relative to a total weight of the etchant liquid composition. 
     
     
         14 . The liquid etchant composition of  claim 12 , wherein the at least one additive comprises the metal corrosion inhibitor in an amount within a range of 1 to 5 wt % relative to a total weight of the etchant liquid composition. 
     
     
         15 . The liquid etchant composition of  claim 12 , wherein the main etchant consists of TMAH, an amount of TMAH is within a range of 4.5-5.5 wt % relative to a total weight of the etchant liquid composition. 
     
     
         16 . The liquid etchant composition of  claim 12 , wherein the main etchant consists of NH 4 OH that is formed from NH 3  dissolved in the liquid etchant composition in a concentration of 5 to 10 wt %. 
     
     
         17 . The liquid etchant composition of  claim 12 , wherein the metal corrosion inhibitor comprises a TiN corrosion inhibitor. 
     
     
         18 . The liquid etchant composition of  claim 17 , wherein the TiN corrosion inhibitor comprises at least one compound selected from diprotic carboxylic acids and phenolic compounds.