Semiconductor device and method of manufacturing the same
View Patent ↗A body contact layer 18 is formed on the side of a recessed structure 17 as well as in the bottom of the recessed structure 17 , so that a contact area between the body contact layer 18 and a well layer 12 is increased and the amount of dopant implanted to the body contact layer 18 is suppressed.
1. A semiconductor device comprising:
a semiconductor substrate of a first conductivity type;
a drain layer of the first conductivity type on a surface of the semiconductor substrate;
a well layer of a second conductivity type on a surface of the drain layer;
trenches formed at least in the well layer, the trench including a gate insulating film formed on an inner surface of the trench;
gate electrodes formed in the respective trenches;
source layers of the first conductivity type on a surface of the well layer, the source layer being in contact with the trench;
a recessed structure formed in a surface region of the well layer so as to face the trench via the source layer;
a body contact layer of the second conductivity type on the surface of the well layer, on a bottom and a side of the recessed structure;
insulating films covering the respective gate electrodes;
a source electrode formed over a surface containing the source layers and the body contact layer; and
a drain electrode formed on a back side of the semiconductor substrate,
wherein the well layer has a higher dopant concentration of the second conductivity type than a dopant concentration of the drain layer of the first conductivity type, and the source layer of the first conductivity type and the body contact layer of the second conductivity type have higher dopant concentrations than the dopant concentration of the second conductivity type of the well layer.
2. The semiconductor device according to claim 1 , further comprising a tapered portion formed on the side of the recessed structure.
3. The semiconductor device according to claim 1 , wherein the dopant concentration of the first conductivity type on a surface of the source layer is at least 1E19/cm 3 , the dopant concentration of the second conductivity type of the well layer is 1E15/cm 3 to 5E17/cm 3 , and the dopant concentration of the second conductivity type of the body contact layer is at least 1E19/cm 3 .
4. The semiconductor device according to claim 1 , wherein the body contact layer is formed continuously to a part of a side of the source layer.