Layout for Needle Cell Trench MOSFET

A power semiconductor die, comprising:

• a front side load terminal;
• a back side load terminal;
• an active region with a plurality of trench cells formed in a semiconductor body, each trench cell comprising:
• a section of a drift zone of a first conductivity type, a section of a channel zone of a second conductivity type and a section of a source zone of the first conductivity type, the channel zone section being electrically connected to the front side load terminal and isolating the source zone section from the drift zone section;
• a control section with at least one control electrode in a control trench;
• and
• a needle-shaped field plate trench;
• a plurality of mesa contact plugs extending from the front side load terminal into the semiconductor body to contact the channel zone sections of the plurality of trench cells;
• an edge termination region between an edge of the power semiconductor die and the active region;
• and
• an isolating trench structure laterally surrounding some or all outermost ones of the mesa contact plugs so that the outermost ones of the mesa contact plugs surrounded by the isolating trench structure are electrically isolated from the edge termination region.

A method of processing a power semiconductor die, the power semiconductor die being configured to conduct a load current between a front side load terminal and a back side load terminal of the power semiconductor die, the method comprising:

• forming an active region with a plurality of columnar trench cells, each columnar trench cell comprising:
• a section of a drift zone of a first conductivity type, a section of a channel zone of a second conductivity type and a source zone of the first conductivity type, the channel zone section being electrically connected to the front side load terminal and isolating the source zone from the drift zone section;
• and a control section with at least one control electrode in a control trench, the control section being configured to induce an inversion channel within the channel zone section for conduction of the load current, the power semiconductor die having a die edge and an edge termination region between the die edge and the active region, the edge termination region including a front side zone configured to have an electrical potential different from an electrical potential of the front side load terminal;
• providing an isolating trench structure arranged between the front side zone and the channel zone which is electrically connected to the front side load terminal.