| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce a leakage current caused in an insulating layer side wall between a gate electrode and a cathode base board without impairing mechanical strength of an element by arranging emitter electrodes in a cavity formed between a columnar insulating layer and a gate layer, and forming pares reaching the columnar insulating layer in an outer peripheral part of an emitter electrode forming area. SOLUTION: A side wall 7 becoming a leak path is eliminated by removing a part except for a place to support a gate electrode 4 among an insulating layer 3 existing between the gate electrode 4 and a cathode base board 1. Therefore, the side wall area is reduced, and a leakage current is reduced, and since the insulating layer is removed, parasitic capacity is also reduced. In an emitter area outer peripheral part, since an insulating layer side wall is kept away from emitter electrodes 2a and 2b, density in which the emitter electrodes scattered by sputtering at operation time stick to the side wall, can be reduced, and the leakage current is reduced.</p> |
