Semiconductor device having lateral diode

Abstract

A semiconductor device having a lateral diode includes a semiconductor layer, a first semiconductor region in the semiconductor layer, a contact region having an impurity concentration greater than that of the first semiconductor region, a second semiconductor region located in the semiconductor layer and separated from the contact region, a first electrode electrically connected through the contact region to the first semiconductor region, and a second electrode electrically connected to the second semiconductor region. The second semiconductor region includes a low impurity concentration portion, a high impurity concentration portion, and an extension portion. The second electrode forms an ohmic contact with the high impurity concentration portion. The extension portion has an impurity concentration greater than that of the low impurity concentration portion and extends in a thickness direction of the semiconductor layer.

1 - 6 . (canceled) 
     
     
         7 . A semiconductor device having a lateral diode, the semiconductor device comprising:
 a semiconductor substrate including a first conductivity-type semiconductor layer;   a first conductivity-type first semiconductor region located in the semiconductor layer;   a first conductivity-type contact region having an impurity concentration greater than an impurity concentration of the first semiconductor region;   a second conductivity-type second semiconductor region located in the semiconductor layer and separated from the contact region;   a first electrode electrically connected through the contact region to the first semiconductor region; and   a second electrode electrically connected to the second semiconductor region, wherein   one of the first semiconductor region and the second semiconductor region is a cathode region,   the other of the first semiconductor region and the second semiconductor region is an anode region,   one of the first electrode and the second electrode is a cathode electrode of the lateral diode, the one of the first electrode and the second electrode being connected to the cathode region,   the other of the first electrode and the second electrode is an anode electrode of the lateral diode, the other of the first electrode and the second electrode being connected to the anode region,   the second semiconductor region includes a low impurity concentration portion, a high impurity concentration portion, and an extension portion,   the low impurity concentration portion is in contact with the high impurity concentration portion and has an impurity concentration less than an impurity concentration of the high impurity concentration portion,   the second electrode forms an ohmic contact with the high impurity concentration portion,   the extension portion has an impurity concentration greater than the impurity concentration of the low impurity concentration portion and extends in a thickness direction of the semiconductor layer,   the contact region has a straight portion,   the high impurity concentration portion has a straight portion on each side of the contact region,   the low impurity concentration portion has a straight portion on each side of the contact region,   the extension portion is located outside the low impurity concentration portion and the high impurity concentration portion with respect to the contact region,   the straight portion of the high impurity concentration portion is located in the center of the low impurity concentration portion in a width direction of the low impurity concentration portion, and   the width direction of the low impurity concentration portion is perpendicular to a longitudinal direction of the contact region.   
     
     
         8 . The semiconductor device according to  claim 7 , wherein
 the high impurity concentration portion further has a projection extending perpendicularly from its straight portion and connected to the extension portion.   
     
     
         9 . A semiconductor device having a lateral diode, the semiconductor device comprising:
 a semiconductor substrate including a first conductivity-type semiconductor layer;   a first conductivity-type first semiconductor region located in the semiconductor layer;   a first conductivity-type contact region having an impurity concentration greater than an impurity concentration of the first semiconductor region;   a second conductivity-type second semiconductor region located in the semiconductor layer and separated from the contact region;   a first electrode electrically connected through the contact region to the first semiconductor region; and   a second electrode electrically connected to the second semiconductor region, wherein   one of the first semiconductor region and the second semiconductor region is a cathode region,   the other of the first semiconductor region and the second semiconductor region is an anode region,   one of the first electrode and the second electrode is a cathode electrode of the lateral diode, the one of the first electrode and the second electrode being connected to the cathode region,   the other of the first electrode and the second electrode is an anode electrode of the lateral diode, the other of the first electrode and the second electrode being connected to the anode region,   the second semiconductor region includes a low impurity concentration portion, a high impurity concentration portion, and an extension portion,   the low impurity concentration portion is in contact with the high impurity concentration portion and has an impurity concentration less than an impurity concentration of the high impurity concentration portion,   the second electrode forms an ohmic contact with the high impurity concentration portion,   the extension portion has an impurity concentration greater than the impurity concentration of the low impurity concentration portion and extends in a thickness direction of the semiconductor layer,   the first semiconductor region has a trench at a position corresponding to the first electrode,   the contact region is located on an inner surface of the trench, and   the first electrode is located in the trench in such a manner that the first electrode and the contact region are electrically connected together inside the trench.   
     
     
         10 . A semiconductor device having a lateral diode, the semiconductor device comprising:
 a semiconductor substrate including a first conductivity-type semiconductor layer;   a first conductivity-type first semiconductor region located in the semiconductor layer;   a first conductivity-type contact region having an impurity concentration greater than an impurity concentration of the first semiconductor region;   a second conductivity-type second semiconductor region located in the semiconductor layer and separated from the contact region;   a first electrode electrically connected through the contact region to the first semiconductor region; and   a second electrode electrically connected to the second semiconductor region, wherein   one of the first semiconductor region and the second semiconductor region is a cathode region,   the other of the first semiconductor region and the second semiconductor region is an anode region,   one of the first electrode and the second electrode is a cathode electrode of the lateral diode, the one of the first electrode and the second electrode being connected to the cathode region,   the other of the first electrode and the second electrode is an anode electrode of the lateral diode, the other of the first electrode and the second electrode being connected to the anode region,   the second semiconductor region includes a low impurity concentration portion, a high impurity concentration portion, and an extension portion,   the low impurity concentration portion is in contact with the high impurity concentration portion and has an impurity concentration less than an impurity concentration of the high impurity concentration portion,   the second electrode forms an ohmic contact with the high impurity concentration portion,   the extension portion has an impurity concentration greater than the impurity concentration of the low impurity concentration portion and extends in a thickness direction of the semiconductor layer,   the first electrode has a first barrier metal layer in contact with the contact region, and   the second electrode has a second barrier metal layer in contact with the second semiconductor region.   
     
     
         11 . (canceled) 
     
     
         12 . A semiconductor device having a lateral diode, the semiconductor device comprising:
 a semiconductor substrate including a first conductivity-type semiconductor layer;   a first conductivity-type first semiconductor region located in the semiconductor layer;   a first conductivity-type contact region having an impurity concentration greater than an impurity concentration of the first semiconductor region;   a second conductivity-type second semiconductor region located in the semiconductor layer and separated from the contact region;   a first electrode electrically connected through the contact region to the first semiconductor region; and   a second electrode electrically connected to the second semiconductor region, wherein   one of the first semiconductor region and the second semiconductor region is a cathode region,   the other of the first semiconductor region and the second semiconductor region is an anode region,   one of the first electrode and the second electrode is a cathode electrode of the lateral diode, the one of the first electrode and the second electrode being connected to the cathode region,   the other of the first electrode and the second electrode is an anode electrode of the lateral diode, the other of the first electrode and the second electrode being connected to the anode region,   the second semiconductor region includes a low impurity concentration portion, a high impurity concentration portion, and an extension portion,   the low impurity concentration portion is in contact with the high impurity concentration portion and has an impurity concentration less than an impurity concentration of the high impurity concentration portion,   the second electrode forms an ohmic contact with the high impurity concentration portion,   the extension portion has an impurity concentration greater than the impurity concentration of the low impurity concentration portion and extends in a thickness direction of the semiconductor layer, and   the contact region is in contact with only a portion of a back surface of the first electrode.   
     
     
         13 . The semiconductor device according to  claim 12 , further comprising:
 a second conductivity-type layer located below the first electrode, wherein   the first electrode is electrically connected to the contact region and the second conductivity-type layer.