Schottky diode and method of fabricating the same

Abstract

A schottky diode may include a schottky junction including a well formed in a semiconductor substrate and a first electrode contacting the first well. The well may have a first conductivity type. A first ohmic junction may include a first junction region formed in the well and a second electrode contacting the first junction region. The first junction region may have a higher concentration of the first conductivity type than the well. A first device isolation region may be formed in the semiconductor substrate separating the schottky junction and the first ohmic junction. A well guard having a second conductivity type opposite to the first conductivity type may be formed in the well. At least a portion of the well guard may, be formed under a portion of the schottky junction.

1 . A schottky diode comprising:
 a schottky junction including a well formed in a semiconductor substrate and a first electrode contacting the well, the well having a first conductivity type;   a first ohmic junction including a first junction region formed in the well and a second electrode contacting the first junction region, the first junction region having a higher concentration of the first conductivity type than the well;   a first device isolation region formed in the semiconductor substrate separating the schottky junction and the first ohmic junction; and   a well guard having a second conductivity type opposite to the first conductivity type formed in the well, at least a portion of the well guard formed under a portion of the schottky junction.   
   
   
       2 . The schottky diode of  claim 1 , wherein the first device isolation region and the first electrode are spaced apart from each other. 
   
   
       3 . The schottky diode of  claim 1 , wherein at least a portion of the well guard is formed under an outer perimeter portion of the schottky junction. 
   
   
       4 . The schottky diode of  claim 1 , wherein the well guard is formed in the shape of a ring having one of a square shape, a rectangular shape, a circular shape, arid an elliptical shape. 
   
   
       5 . The schottky diode of  claim 1 , wherein each of the first and second electrodes include a silicide. 
   
   
       6 . The schottky diode of  claim 5 , wherein the first and second electrodes include a same silicide or different silicides. 
   
   
       7 . The schottky diode of  claim 6 , wherein the first and second electrodes include cobalt silicide. 
   
   
       8 . The schottky diode of  claim 6 , wherein the first electrode includes titanium silicide and the second electrode includes cobalt silicide. 
   
   
       9 . The schottky diode of  claim 1 , further comprising:
 a second ohmic junction formed to induce a leakage current to flow from the well to the semiconductor substrate; and   a second device isolation region separating the first ohmic junction and the second ohmic junction.   
   
   
       10 . The schottky diode of  claim 9 , wherein the second ohmic junction includes a second junction region formed in the well and a third electrode contacting the second junction region, the second junction region having a higher concentration of the second conductivity type than a concentration of the second conductivity type in the well guard. 
   
   
       11 . A method for fabricating a schottky diode, the method comprising:
 forming a well having a first conductivity type in a semiconductor substrate;   forming a first device isolation region in the well to separate a schottky junction region from a first ohmic junction region;   forming a well guard having a second conductivity type opposite to the first conductivity type in the well, at least a portion of the well guard formed in a portion of the schottky junction region;   forming a first junction region in the first ohmic junction region, the first junction region having a higher concentration of the first conductivity type than the well; and   forming an electrode over the first ohmic junction region contacting the first junction region.   
   
   
       12 . The method of  claim 11 , further comprising forming an electrode over the schottky junction region simultaneously with forming the electrode over the first ohmic junction region. 
   
   
       13 . The method of  claim 12 , wherein each of the electrode of the ohmic junction and the electrode of the schottky junction include a silicide. 
   
   
       14 . The method of  claim 13 , wherein the electrode of the ohmic junction and the electrode of the schottky junction include cobalt silicide. 
   
   
       15 . The method of  claim 11 , further comprising:
 forming an interlayer insulation film on the semiconductor substrate;   forming a contact hole in the interlayer insulation film exposing at least a portion of the schottky junction region; and   forming an electrode in the schottky junction region by forming a barrier metal film covering the interlayer insulation film and the schottky junction region and applying a heat treatment to the barrier metal film to form a suicide in the schottky junction region.   
   
   
       16 . The method of  claim 15 , wherein each of the electrode of the ohmic junction and the electrode of the schottky junction include a silicide. 
   
   
       17 . The method of  claim 16 , wherein the electrode of the ohmic junction includes cobalt silicide and the electrode of the schottky junction includes titanium silicide. 
   
   
       18 . The method of  claim 11 , further comprising:
 forming a second ohmic junction in the semiconductor substrate; and   forming a second device isolation region separating the first ohmic junction and the second ohmic junction,   wherein the second ohmic junction induces a leakage current to flow from the well to the semiconductor substrate.   
   
   
       19 . The method of  claim 18 , wherein forming the second ohmic junction includes forming a second junction region in the semiconductor substrate and forming an electrode contacting the second junction region, the second junction region having a higher concentration of the second conductivity type than the well guard. 
   
   
       20 . The method of  claim 11 , wherein the schottky diode is fabricated simultaneously with an NMOS transistor, a PMOS transistor, or a CMOS transistor which is formed on the same semiconductor substrate where the schottky diode is formed.