Semiconductor device and its manufacturing method

Abstract

A semiconductor device comprises a semiconductor substrate; a trench formed in the semiconductor substrate or in a layer deposited on the semiconductor substrate; a first conductive layer deposited in the trench and having a recess in the top surface thereof; a buried layer which buries the recess of the first conductive layer and which is made of a material having a melting point lower than that of the first conductive layer; and a second conductive layer formed on the buried layer inside the trench and electrically connected to the first conductive layer.

1 - 16 . (canceled)  
   
   
       17 . A semiconductor device comprising: 
 a semiconductor substrate;    an insulating film formed on the semiconductor substrate;    a contact hole formed in the insulating film;    a first conductor buried in a lower portion of the contact hole, including a seam formed in the first conductor and a recess formed in a top surface of the first conductor in relation to the seam;    a buried conductive layer formed on the recess; and    a second conductor formed on the buried layer.    
   
   
       18 . The semiconductor device according to  claim 17 , wherein the recess of the first conductor is approximately V-shaped in a cross section thereof.  
   
   
       19 . The semiconductor device according to  claim 17 , wherein the first conductor comprises a doped polysilicon.  
   
   
       20 . The semiconductor device according to  claim 17 , wherein the second conductor comprises a metal.  
   
   
       21 . The semiconductor device according to  claim 17 , wherein the buried conductive layer comprises a material which has a melting point lower than a melting point of the first conductor.  
   
   
       22 . The semiconductor device according to  claim 17 , wherein the buried conductive layer comprises germanium or silicon germanium.  
   
   
       23 . The semiconductor device according to  claim 17 , wherein the first conductor comprises a lower end portion in contact with an upper surface of the semiconductor substrate.  
   
   
       24 . The semiconductor device according to  claim 17 , wherein the first conductor comprises a lower end portion in contact with a source/drain diffusion layer of the semiconductor substrate.  
   
   
       25 . A semiconductor device comprising: 
 a semiconductor substrate;    an insulating film formed on the semiconductor substrate;    a contact hole formed in the insulating film;    a first conductor buried in a lower portion of the contact hole, including a recess formed in a top surface of the first conductor, the recess being approximately V-shaped in a cross section thereof;    a buried conductive layer formed on the recess; and    a second conductor formed on the buried layer.    
   
   
       26 . The semiconductor device according to  claim 25 , wherein the first conductor comprises a seam connected to the recess.  
   
   
       27 . The semiconductor device according to  claim 25 , wherein the first conductor comprises a doped polysilicon.  
   
   
       28 . The semiconductor device according to  claim 25 , wherein the second conductor comprises a metal.  
   
   
       29 . The semiconductor device according to  claim 25 , wherein the buried conductive layer comprises a material which has a melting point lower than a melting point of the first conductor.  
   
   
       30 . The semiconductor device according to  claim 25 , wherein the buried conductive layer comprises germanium or silicon germanium.  
   
   
       31 . The semiconductor device according to  claim 25 , wherein the first conductor comprises a lower end portion in contact with an upper surface of the semiconductor substrate.  
   
   
       32 . The semiconductor device according to  claim 25 , wherein the first conductor comprises a lower end portion in contact with a source/drain diffusion layer of the semiconductor substrate.