High reliability-high voltage junction termination with charge dissipation layer

A method of making a high voltage power semiconductor device, the method comprising:

• providing a substrate formed of a doped silicon layer of a first polarity having an upper surface;
• defining on the substrate an active device area having a periphery and a junction termination area surrounding the active device area;
• forming a junction termination of a second polarity opposite the first polarity in the substrate and extending to the surface thereof;
• forming a tunneling oxide layer on the upper surface of the substrate over the junction termination area;
• depositing a layer consisting of undoped polysilicon over the tunneling oxide layer overlaying the junction termination area;
• and
• coupling the undoped polysilicon layer electrically to an outer edge of the junction termination structure and to a grounded electrode inside of the active area.

A high voltage power semiconductor device comprising:

• a substrate having an upper surface and including an active device area having a periphery and a junction termination area surrounding the active device area, the substrate being formed of a doped silicon layer of a first polarity;
• a junction termination structure including one or more regions of a second polarity opposite the first polarity formed in the substrate and extending to the surface thereof to form one or more termination junctions in the junction termination area surrounding the active device;
• a tunneling oxide layer overlaying the junction termination area surrounding the active device area in contact with the silicon substrate upper surface;
• a layer consisting of undoped polysilicon overlaying the tunneling oxide layer and spanning the junction termination area in contact with the silicon substrate upper surface;
• and
• connections to an outer edge of the junction termination structure and to a grounded electrode inside of the active area;
• the tunneling oxide layer having a thickness that permits hot carriers formed at substrate upper surface to pass through the tunneling oxide layer into the undoped polysilicon layer to be dissipated;
• and
• the undoped polysilicon layer being patterned as a network over the junction termination structure in which a strip of the polysilicon layer is positioned adjacent each of the rings of a second polarity and the strips are interconnected by charge dissipation bars.

A method of making a high voltage power semiconductor device, the method comprising:

• providing a substrate formed of a doped silicon layer of a first polarity having an upper surface;
• defining on the substrate an active device area having a periphery and a junction termination area surrounding the active device area;
• forming a junction termination of a second polarity opposite the first polarity in the substrate and extending to the surface thereof;
• forming a tunneling oxide layer on the upper surface of the substrate over the junction termination area;
• depositing a layer consisting of undoped polysilicon over the tunneling oxide layer overlaying the junction termination area;
• coupling the undoped polysilicon layer electrically to an outer edge of the junction termination structure and to a grounded electrode inside of the active area, and
• patterning the undoped polysilicon layer as a network over the junction termination structure in which a strip of the polysilicon layer is positioned adjacent each of the rings of a second polarity and the strips are interconnected by charge dissipation bars.