Semiconductor devices and methods to form trenches in semiconductor devices

Abstract

Semiconductor devices and methods of fabricating the same are disclosed. One example method may include forming sequentially a pad oxide film and a silicon nitride film on an entire surface of a semiconductor substrate, forming the trench by etching the silicon nitride film and the semiconductor substrate up to a predetermined depth, and forming a liner oxide film with a thickness thinner than that of the silicon nitride film on an inner wall of the trench. The example method may also include applying a negative voltage to a back surface of the semiconductor substrate and forming an insulation film to fill the trench on the liner oxide film.

1 . A method of forming a trench in semiconductor device, the method comprising: 
 forming sequentially a pad oxide film and a silicon nitride film on an entire surface of a semiconductor substrate;    forming the trench by etching the silicon nitride film and the semiconductor substrate up to a predetermined depth;    forming a liner oxide film with a thickness thinner than that of the silicon nitride film on an inner wall of the trench;    applying a negative voltage to a back surface of the semiconductor substrate; and    forming an insulation film to fill the trench on the liner oxide film.    
     
     
         2 . A method as defined by  claim 1 , wherein applying the negative voltage includes applying a voltage of −2000V to −1000V to the back surface of the semiconductor substrate.  
     
     
         3 . A method as defined by  claim 1 , wherein applying the negative voltage includes using one of a method of applying the negative voltage to the back surface of the semiconductor substrate using an electrostatic chuck (ESC) and a method of injecting electrons into the back surface of the semiconductor substrate using an electron gun.  
     
     
         4 . A method as defined by  claim 1 , wherein the silicon nitride film is formed at a thickness of about 1000-3000 Å.  
     
     
         5 . A method as defined by  claim 1 , wherein the liner oxide film is formed at a thickness of about 100-500 Å by a thermal oxidation process.  
     
     
         6 . A method as defined by  claim 1 , wherein forming the insulation film includes forming a filling oxide film to fill the trench on an entire surface of the silicon nitride film and then chemical mechanical polishing the filling oxide film until the silicon nitride film is exposed.  
     
     
         7 . A method as defined by  claim 6 , wherein the filling oxide film is formed by one of an atmospheric pressure chemical vapor deposition (APCVD) method and a subatmospheric chemical vapor deposition (SACVD) method.  
     
     
         8 . A method as defined by  claim 6 , wherein the filling oxide film is formed at a thickness of about 6000-12000 Å.  
     
     
         9 . A semiconductor device, comprising: 
 a semiconductor substrate having a trench of a predetermined depth;    a pad oxide and a silicon nitride film sequentially formed on an entire surface of the semiconductor substrate except for the trench;    a liner oxide film formed at an inner wall of the trench and having a thickness thinner than the silicon nitride film; and    an insulation film formed on the liner oxide film for filling the trench,    wherein the insulation film is deposited such that the trench is filled, under a state where charges stored in the liner oxide film are more than those stored in the silicon nitride film by an application of a negative voltage to the back surface of the semiconductor substrate.    
     
     
         10 . A semiconductor device as defined by  claim 9 , wherein the application of the negative voltage to the back surface of the semiconductor substrate is performed by one of electron injection using an electrostatic chuck and an electron gun.  
     
     
         11 . A semiconductor device as defined by  claim 9 , wherein the negative voltage is −2000V to −1000V.  
     
     
         12 . A semiconductor device as defined by  claim 9 , wherein the silicon nitride film is formed at a thickness of about 1000-3000 Å.  
     
     
         13 . A semiconductor device as defined by  claim 9 , wherein the liner oxide film is formed at a thickness of about 100-500 Å by a thermal diffusion process.