Semiconductor device and method for fabricating the same

Abstract

A semiconductor device is formed by depositing a nitride material having a lower etch rate than an oxide material over or between buried gates when forming a metal contact at an end portion of a cell region, to prevent a lower substrate from being etched during an etching process forming a metal contact hole. The semiconductor device includes at least one buried gate formed in a device isolation film of a semiconductor substrate, an etch stop film formed over and between the buried gates, and a metal contact formed perpendicular to the buried gate in the etch stop film.

1 - 4 . (canceled) 
     
     
         5 . A method for fabricating a semiconductor device comprising:
 forming an insulation film in a cell region including a buried gate and a bit line structure and in a peripheral region including a peri-gate structure;   forming an open region to expose a sidewall of the buried gate located in an end portion of the cell region, by etching some portions of the insulation film located in the end portion of the cell region;   depositing an etch stop material over the cell region including the open region and over the peripheral region;   forming an etch stop film by etching the etch stop material in the cell region using a cell-open mask;   forming a first metal contact hole, perpendicular to the buried gate, in the etch stop film; and   forming a metal contact by filling a conductive material in the first metal contact hole.   
     
     
         6 . The method according to  claim 5 , wherein the step of forming the open region includes:
 simultaneously forming a first trench extending to a device isolation film in a center part of the cell region.   
     
     
         7 . The method according to  claim 6 , wherein the step of depositing the etch stop material includes:
 depositing the etch stop material over the first trench.   
     
     
         8 . The method according to  claim 5 , wherein the step of depositing the etch stop material includes:
 depositing the etch stop material over and between the buried gates.   
     
     
         9 . The method according to  claim 5 , wherein the step of forming the etch stop film includes:
 forming a second trench for storage node formation by etching the etch stop material in a center part of the cell region; and   depositing a conductive material in the second trench.   
     
     
         10 . The method according to  claim 5 , wherein the step of forming the first metal contact hole perpendicular to each buried gate includes:
 simultaneously forming a second metal contact hole at both sides of the peri-gate structure in the peripheral region.   
     
     
         11 . The method according to  claim 6 , wherein the etch stop film material has a lower etch rate than the device isolation film. 
     
     
         12 . The method according to  claim 5 , wherein the etch stop film material is a nitride material. 
     
     
         13 - 26 . (canceled)