Semiconductor circuit, method of driving the same and semiconductor device

Abstract

A semiconductor circuit or a semiconductor device has the current-voltage characteristic that, in a blocking state of the semiconductor circuit or the semiconductor device, a current gently flows for values of a voltage equal to or greater than a first voltage value but equal to or smaller than a second voltage value, whereas a current abruptly flows for values of a voltage greater than the second voltage value. Due to the current-voltage characteristic, energy accumulated in an inductance provided within the circuit is consumed by a differential resistance of the semiconductor circuit or a semiconductor, thereby preventing the occurrence of the electromagnetic noise and an excessively large voltage.

What is claimed is:  
     
         1 . A semiconductor circuit comprising a circuit including at least a semiconductor device and an inductance connected to said circuit wherein a flowing current is controlled to flowing and cut-off states, 
 wherein, for values of a blocking-direction voltage applied to terminals of said circuit including said semiconductor device equal to or greater than a first voltage value but equal to or smaller than a second voltage value, the magnitude of a current increases with an increase in said blocking-direction voltage and, for values of said blocking-direction voltage equal to or greater than said second voltage value, said current rises at a rate of increase greater than a rate of increase for values of said blocking-direction voltage equal to or greater than said first voltage value but equal to or smaller than said second voltage value.    
     
     
         2 . A semiconductor circuit according to  claim 1  wherein said semiconductor device comprises a semiconductor switching device.  
     
     
         3 . A semiconductor circuit according to  claim 1  wherein said semiconductor device comprises a diode.  
     
     
         4 . A semiconductor circuit according to  claim 1  wherein said circuit including said semiconductor device comprises a snubber circuit.  
     
     
         5 . A semiconductor circuit including at least a semiconductor device, 
 wherein, for values of a blocking-direction voltage applied to terminals of said semiconductor circuit equal to or greater than a first voltage value but equal to or smaller than a second voltage value, the magnitude of a current increases with an increase in said blocking direction voltage and, for values of said blocking-direction voltage equal to or greater than said second voltage value, said current rises at a rate of increase greater than a rate of increase for values of said blocking-direction voltage equal to or greater than said first voltage value but equal to or smaller than said second voltage value.    
     
     
         6 . A semiconductor circuit according to  claim 5  wherein said semiconductor device comprises a semiconductor switching device.  
     
     
         7 . A semiconductor circuit according to  claim 5  wherein said semiconductor device comprises a diode.  
     
     
         8 . A semiconductor circuit according to  claim 5  wherein said semiconductor device comprises a plurality of diodes having breakdown voltages different from each other.  
     
     
         9 . A semiconductor circuit comprising a circuit including at least a semiconductor device and a semiconductor switching device interposed in parallel between terminals of said circuit wherein, for values of a blocking-direction voltage applied to said terminals of said circuit equal to or greater than a first voltage value but equal to or smaller than a second voltage value, the magnitude of a current increases with an increase in said blocking-direction voltage and, for values of said blocking-direction voltage equal to or greater than said second voltage value, said current rises at a rate of increase greater than a rate of increase for values of said blocking-direction voltage equal to or greater than said first voltage value but equal to or smaller than said second voltage value.  
     
     
         10 . A method of driving a semiconductor circuit including a semiconductor switching device comprising supplying a control signal to said semiconductor switching device in accordance with a blocking-direction voltage applied to main terminals of said semiconductor switching device in such a way that, for values of said blocking-direction voltage equal to or greater than a first voltage value but equal to or smaller than a second voltage value, the magnitude of a main current increases with an increase in said blocking-direction voltage and, for values of said blocking-direction voltage equal to or greater than said second voltage value, said main current rises at a rate of increase greater than a rate of increase for values of said blocking-direction voltage equal to or greater than said first voltage value but equal to or smaller than said second voltage value.  
     
     
         11 . A semiconductor device comprising a pair of main terminals wherein, for values of a blocking-direction voltage applied to said main terminals equal to or greater than a first voltage value but equal to or smaller than a second voltage value, the magnitude of a main current increases with an increase in said blocking-direction voltage and, for values of said blocking-direction voltage equal to or greater than said second voltage value, said main current rises at a rate of increase greater than a rate of increase for values of said blocking-direction voltage equal to or greater than said first voltage value but equal to or smaller than said second voltage value.  
     
     
         12 . A semiconductor device comprising: 
 a 1st semiconductor layer of a 1st conduction type;    a 2nd semiconductor layer of a 2nd conduction type provided on said 1st semiconductor layer;    a 3rd semiconductor layer of the 1st conduction type adjacent to said 2nd semiconductor layer;    a 4th semiconductor layer of the 2nd conduction type adjacent to said 1st semiconductor layer;    a 5th semiconductor layer of the 1st conduction type adjacent to said 1st and 4th semiconductor layers;    a 1st main electrode in ohmic contact with said 2nd and 3rd semiconductor layers;    a 2nd main electrode in ohmic contact with said 4th and 5th semiconductor layers; and    an isolation gate electrode extending over said 1st, 2nd and 3rd semiconductor layers,    wherein a junction between said 1st and 4th semiconductor layers exists at a location closer to a junction between said 1st and 2nd semiconductor layers than a junction between said 1st and 5th semiconductor layers does.    
     
     
         13 . A semiconductor device comprising: 
 a 1st semiconductor layer of a 1st conduction type;    a 2nd semiconductor layer of a 2nd conduction type provided on said 1st semiconductor layer;    a 3rd semiconductor layer of the 1st conduction type adjacent to said 2nd semiconductor layer;    a 4th semiconductor layer of the 2nd conduction type adjacent to said 1st semiconductor layer;    a 5th semiconductor layer of the 1st conduction type adjacent to said 1st and 4th semiconductor layers;    a 1st main electrode in ohmic contact with said 2nd and 3rd semiconductor layers;    a 2nd main electrode in ohmic contact with said 4th and 5th semiconductor layers; and    an isolation gate electrode extending over said 1st, 2nd and 3rd semiconductor layers,    wherein the number of impurities of the 1st conduction type in a unit area on said 1st semiconductor layer sandwiched by a junction between said 1st and 2nd semiconductor layers and a junction between said 1st and 4th semiconductor layers is equal to or smaller than (εm)·(εs)/q where symbol εm denotes the avalanche-breakdown electric field of a material used for making said 1st semiconductor layer, symbol εs is the dielectric constant of said material and q is the amount of electric charge of an electron.    
     
     
         14 . A semiconductor device comprising: 
 a 1st semiconductor layer of a 1st conduction type;    a 2nd semiconductor layer of a 2nd conduction type and a 3rd semiconductor layer of the 2nd conduction type provided on said 1st semiconductor layer;    a 4th semiconductor layer of the 1st conduction type and a 5th semiconductor layer of the 1st conduction type adjacent to said 2nd semiconductor layer;    a 6th semiconductor layer of the 1st conduction type adjacent to said 3rd semiconductor layer;    a 7th semiconductor layer of the 2nd conduction type adjacent to said 1st;    an 8th semiconductor layer of the 1st conduction type adjacent to said 1st and 7th semiconductor layers;    a 1st main electrode in ohmic contact with said 2nd and 4th semiconductor layers;    a 2nd main electrode in ohmic contact with said 7th and 8th semiconductor layers;    a 1st isolation gate electrode extending over said 2nd, 4th and 5th semiconductor layers; and    a 2nd isolation gate electrode extending over said 1st, 2nd and 3rd semiconductor layers;    wherein said 5th and 6th semiconductor layers are electrically connected to each other,    wherein a junction between said 1st and 7th semiconductor layers exists at a location closer to a junction between said 1st and 2nd semiconductor layers than a junction between said 1st and 8th semiconductor layers does.    
     
     
         15 . A semiconductor device comprising: 
 a 1st semiconductor layer of a 1st conduction type;    a 2nd semiconductor layer of a 2nd conduction type and a 3rd semiconductor layer of the 2nd conduction type provided on said 1st semiconductor layer;    a 4th semiconductor layer of the 1st conduction type and a 5th semiconductor layer of the 1st conduction type adjacent to said 2nd semiconductor layer;    a 6th semiconductor layer of the 1st conduction type adjacent to said 3rd semiconductor layer;    a 7th semiconductor layer of the 2nd conduction type adjacent to said 1st;    an 8th semiconductor layer of the 1st conduction type adjacent to said 1st and 7th semiconductor layers;    a 1st main electrode in ohmic contact with said 2nd and 4th semiconductor layers;    a 2nd main electrode in ohmic contact with said 7th and 8th semiconductor layers;    a 1st isolation gate electrode extending over said 2nd, 4th and 5th semiconductor layers; and    a 2nd isolation gate electrode extending over said 1st, 2nd and 3rd semiconductor layers,    wherein the number of impurities of the 1st conduction type in a unit area on said 1st semiconductor layer sandwiched by a junction between said 1st and 2nd semiconductor layers and a junction between said 1st and 7th semiconductor layers is equal to or smaller than (ε m )·(ε s )/q where symbol ε m  denotes the avalanche-breakdown electric field of a material used for making said 1st semiconductor layer, symbol ε s  is the dielectric constant of said material and q is the amount of electric charge of an electron.    
     
     
         16 . A diode comprising: 
 a 1st semiconductor layer of a 1st conduction type;    a 2nd semiconductor layer of a 2nd conduction type provided on said 1st semiconductor layer;    a 3rd semiconductor layer of the 2nd conduction type adjacent to said 1st semiconductor layer;    a 4th semiconductor layer of the 1st conduction type adjacent to said 1st and 3rd semiconductor layers;    a 1st main electrode in ohmic contact with said 2nd semiconductor layer; and    a 2nd main electrode in ohmic contact with said 3rd and 4th semiconductor layers,    wherein a junction between said 1st and 3rd semiconductor layers exists at a location closer to a junction between said 1st and 2nd semiconductor layers than a junction between said 1st and 4th semiconductor layers does.    
     
     
         17 . A diode comprising: 
 a 1st semiconductor layer of a 1st conduction type;    a 2nd semiconductor layer of a 2nd conduction type provided on said 1st semiconductor layer;    a 3rd semiconductor layer of the 2nd conduction type adjacent to said 1st semiconductor layer;    a 4th semiconductor layer of the 1st conduction type adjacent to said 1st and 3rd semiconductor layers;    a 1st main electrode in ohmic contact with said 2nd semiconductor layer; and    a 2nd main electrode in ohmic contact with said 3rd and 4th semiconductor layers,    wherein the number of impurities of the 1st conduction type in a unit area on said 1st semiconductor layer sandwiched by a junction between said 1st and 2nd semiconductor layers and a junction between said 1st and 3rd semiconductor layers is equal to or smaller than (ε m )·(ε s )/q where symbol ε m  denotes the avalanche-breakdown electric field of a material used for making said 1st semiconductor layer, symbol ε s  is the dielectric constant of said material and q is the amount of electric charge of an electron.