Planar gate semiconductor device with oxygen-doped Si-layers

A semiconductor device, comprising:

• a semiconductor substrate having a first main surface and a second main surface opposite the first main surface;
• a plurality of transistor cells, each transistor cell comprising a source region of a first conductivity type, a drift zone of the first conductivity type, a body region of a second conductivity type separating the source region from the drift zone, a field plate trench extending into the drift zone and including a field plate, and a planar gate on the first main surface and configured to control current through a channel of the body region;
• a drain region of the first conductivity type at the second main surface;
• and
• a diffusion barrier structure extending along the channel of the body region, the diffusion barrier structure comprising alternating layers of Si and oxygen-doped Si and a Si capping layer on the alternating layers of Si and oxygen-doped Si.

A semiconductor device, comprising:

• a semiconductor substrate having a first main surface and a second main surface opposite the first main surface;
• a plurality of transistor cells, each transistor cell comprising a source region of a first conductivity type, a drift zone of the first conductivity type, a body region of a second conductivity type separating the source region from the drift zone, a field plate trench extending into the drift zone and including a field plate, and a planar gate on the first main surface and configured to control current through a channel of the body region;
• a drain region of the first conductivity type at the second main surface;
• and
• a diffusion barrier structure vertically extending in the semiconductor substrate from the body region of the plurality of transistor cells and into the drift zone between adjacent field plate trenches, the diffusion barrier structure comprising alternating layers of Si and oxygen-doped Si and a Si capping layer on the alternating layers of Si and oxygen-doped Si.