MOS transistor device

A MOS trench transistor device comprising:

• a semiconductor region of a first conductivity type;
• a vertical gate electrode;
• a gate oxide insulating the vertical gate electrode, the vertical gate electrode formed within a deep vertical gate trench within the semiconductor region and having a length defined in a first lateral direction and a thickness defined in a second lateral direction of the semiconductor region, the first lateral direction crossing the second lateral direction;
• a source electrode region of the first conductivity type at the upper section of a mesa region provided within the semiconductor region outside the gate trench and laterally and in parallel adjoining the gate trench, said mesa region having a length and a width, wherein the length of the mesa region extends in the first lateral direction and its width extends in the second lateral direction and said mesa region comprises:
• below the source electrode region a semiconductor body region of a second conductivity type with one or a plurality of assigned semiconductor body contact regions, formed at the upper section of the mesa region;
• the gate oxide being thinner in the upper section and undergoing a transition via a field plate step so as to be thicker in the lower section of the gate trench;
• and
• a drain electrode region of the first conductivity type lying opposite the gate trench in the vertical direction;
• and
• the MOS transistor device comprising a multiplicity of vertical MOS transistors, a gate trench and a mesa region alternating in the second lateral direction;
• each mesa region being a dense trench mesa region which has with respect to an adjacent MOS transistor a width in the second lateral direction that is less than 2.5 times the maximum thickness of the gate oxide in the associated gate trench and in which plural source electrode regions and each body contact regions are successively and alternately provided in the length direction of the mesa region;
• wherein the MOS transistor device furthermore has a deep body reinforcement of the second conductivity type which is provided below the semiconductor body region only at the locations of the body contact region and reaches into the depth of the semiconductor region below a field plate step of the gate oxide but not into a substrate region.

A MOS trench transistor device comprising:

• a semiconductor region of a first conductivity type;
• a vertical gate electrode;
• a gate oxide insulating the vertical gate electrode formed within a deep vertical gate trench extending within the semiconductor region and having a length defined in a first lateral direction and a thickness defined in a second lateral direction of the semiconductor region, the first lateral direction crossing the second lateral direction;
• a source electrode region of the first conductivity type in an upper section of a mesa region provided within the semiconductor region outside of the gate trench and laterally and in parallel adjoining the gate trench, said mesa region having a length and a width, wherein the length of the mesa region extends in the first lateral direction and its width extends in the second lateral direction and the mesa region comprises;
• below the source region a semiconductor body region of a second conductivity type with one or a plurality of assigned semiconductor body contact region formed at the upper section of the mesa region;
• the gate oxide being thinned in the upper section of the gate trench and undergoing transition via a field plate step to a second section situated in the lower section of the gate trench, and a drain electrode region of the first conductivity type lying opposite the gate trench in the vertical direction, and
• the MOS transistor device comprising a multiplicity of vertical MOS transistors, a gate trench and a mesa region always being formed successively in a manner alternating in the second lateral direction, and
• each mesa region being a dense trench mesa region which has with respect to an adjacent MOS transistor a width in the second lateral direction that is less than 2.5 times the maximum thickness of the gate oxide in the associated gate trench and in which plural source electrode regions and each semiconductor body contact regions are successively and alternately provided in the length direction of the mesa region;
• and
• wherein the MOS transistor device furthermore has a deep body reinforcement of the second conductivity type which is provided below the semiconductor body region only at the locations of the body contact regions and reaches into the depth of the semiconductor region below a field plate step but not to a substrate region.