Semiconductor Device

Abstract

In an n-channel type power MISFET, a source electrode in contact with an n + -semiconductor region (source region) and a p + -semiconductor region (back gate contact region) is constituted with an Al film and an underlying barrier film comprised of MoSi 2 , use of the material having higher barrier height relation to n-Si for the barrier film increasing the contact resistance to n-Si and backwardly biasing the emitter and base of a parasitic bipolar transistor making it less tending to turn-on, thereby decreasing the leak current of power MISFET.

1 - 37 . (canceled)  
   
   
       38 . A semiconductor device comprising: 
 (a) a MISFET formed in a semiconductor substrate, including: 
 (a1) a gate portion comprising a first conductor formed in a first trench in the semiconductor substrate;  
 (a2) a source portion comprising a semiconductor region having a first conduction type in contact with a side wall of the gate portion;  
 (a3) a drain portion comprising a semiconductor region having the first conduction type formed on a rear face of the semiconductor substrate; and  
 (a4) a channel portion comprising a semiconductor region having a second conduction type opposite to the first conduction type arranged between the source portion and the drain portion, and  
   (b) a conductive portion formed on the semiconductor substrate and in contact with the source portion and the channel portion, including: 
 (b1) a second conductor; and  
 (b2) an additional conductor arranged between the second conductor and said channel portion,  
   (c) wherein the conductive portion is formed such that a parasitic bipolar transistor, which provides a leakage current path between said source portion and said drain portion, takes an off-state under a predetermined condition which would otherwise cause said parasitic bipolar transistor to take an on-state.    
   
   
       39 . A semiconductor device according to  claim 38 , wherein said predetermined condition is a condition in which a voltage is applied to said drain portion and a voltage between said source portion and said gate portion is zero.  
   
   
       40 . A semiconductor device according to  claim 38 , wherein a material of the additional conductor is selected to provide a barrier height with respect to a material of the channel portion, which is effective to cause the parasitic bipolar transistor to take the off-state.  
   
   
       41 . A semiconductor device according to  claim 40 , wherein said additional conductor is a reaction product including a constituent of the second conductor.  
   
   
       42 . A semiconductor device according to  claim 38 , wherein the parasitic bipolar transistor has an emitter region corresponding to the source portion, a base region corresponding to the channel portion, and a collector region corresponding to the drain portion.  
   
   
       43 . A semiconductor device according to  claim 38 , wherein said conductive portion is formed in a second trench in the semiconductor substrate.  
   
   
       44 . A semiconductor device according to  claim 40 , wherein the first conduction type is n-type, the second conduction type is p-type, and said additional conductor is mainly comprised of an elemental metal or a reaction product thereof, said elemental metal being selected from the group consisting of Co, Ni, Rh, Mo, Pb, Mn, Pt, and Ir.  
   
   
       45 . A semiconductor device according to  claim 40 , wherein the first conduction type is p-type, the second conduction type is n-type, and said additional conductor is mainly comprised of an elemental metal or a reaction product thereof, said elemental metal being selected from the group consisting of Co, Ti, Ta, Cr, Mo, Zr, and Hf.  
   
   
       46 . A semiconductor device comprising: 
 (a) a MISFET formed in a semiconductor substrate, including: 
 (a1) a gate portion comprising a first conductor formed by way of an insulation film on the semiconductor substrate;  
 (a2) a source portion and a drain portion, each comprising a semiconductor region having a first conduction type formed in the semiconductor substrate on both sides of the gate portion; and  
 (a3) a channel portion comprising a semiconductor region having a second conduction type opposite to the first conduction type arranged between the source portion and the drain portion, and  
   (b) a conductive portion formed above the semiconductor substrate and in contact with the source portion or the drain portion and with the channel portion, including: 
 (b1) a second conductor; and  
 (b2) an additional conductor arranged between the second conductor and said channel portion,  
   (c) wherein said conductive portion is formed such that a parasitic bipolar transistor, which provides a leakage current path between said source portion and said drain portion, takes an off-state under a predetermined condition which would otherwise cause said parasitic bipolar transistor to take an on-state.    
   
   
       47 . A semiconductor device according to  claim 46 , wherein said predetermined condition is a condition in which a voltage is applied to said drain portion and a voltage between said source portion and said gate portion is zero.  
   
   
       48 . A semiconductor device according to  claim 46 , wherein a material of the additional conductor is selected to provide a barrier height with respect to a material of the channel portion, which is effective to cause the parasitic bipolar transistor to take an off-state.  
   
   
       49 . A semiconductor device according to  claim 48 , wherein said additional conductor is a reaction product including a constituent of the second conductor.  
   
   
       50 . A semiconductor device according to  claim 46 , wherein the parasitic bipolar transistor has an emitter region corresponding to the source portion, a base region corresponding to the channel portion, and a collector region corresponding to the drain portion.  
   
   
       51 . A semiconductor device according to  claim 46 , wherein, said first conductor of said gate portion is formed by way of the insulation film in a trench in the semiconductor substrate.  
   
   
       52 . A semiconductor device according to  claim 48 , wherein the first conduction type is n-type, the second conduction type is p-type, and said additional conductor is mainly comprised of an elemental metal or a reaction product thereof, said elemental metal being selected from the group consisting of Co, Ni, Rh, Mo, Pb, Mn, Pt, and Ir.  
   
   
       53 . A semiconductor device according to  claim 48 , wherein the first conduction type is p-type, the second conduction type is n-type, and said additional conductor is mainly comprised of an elemental metal or a reaction product thereof, said elemental metal being selected from the group consisting of Co, Ti, Ta, Cr, Mo, Zr, and Hf.