Cross section structure
Planar (gate) structure
Trench (gate) structure
In the planar structure there are gates on the wafer surface, so electrodes can be attached to the surface after processing, but channels will be horizontal so the area of each individual cell will be large.
In the trench structure, grooves (trenches) are carved into the wafer surface and the electrodes are embedded in these trenches.
The channels can then be laid out vertically to make the cell area smaller, which allows for a larger number of cells to be placed, which in turn allows for a smaller ON resistance on the same bare die area.
