Recessed termination for trench schottky device without junction curvature
View Patent ↗A trench type Schottky device has a guard ring diffusion of constant depth between the outermost of an active trench and an outer surrounding termination trench. The junction curvature of the guard ring diffusion is suppressed or cut out by the trenches.
1. A trench type semiconductor device comprising an active area consisting of a plurality of spaced active trenches filled with conductive polysilicon and surrounded by a termination trench which is laterally spaced from an adjacent one of said active trenches; said trenches being formed in a wafer of silicon of one of the conductivity types; and a guard ring diffusion of the other of the conductivity types diffused into the area between said adjacent one of said active trenches and said termination trench and having a constant depth which is less than the depth of said one of said active trenches and the depth of said termination trench; an electrode connected to said conductive polysilicon in said active trenches, and to the surface of said guard ring diffusion and to tops of mesas between said spaced active trenches, thereby to form a schottky device, wherein said guard ring diffusion extends from said adjacent one of said active trenches to said termination trench.
2. The trench type semiconductor device of claim 1 , wherein said guard ring has a depth of about 2μ and a width of about 5μ.
3. The device of claim 2 , wherein each of said trenches are lined with a thin oxide layer.