| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the large-scale breakdown of a gate voltage due to an electric discharge from an anode electrode by forming planar corners in an obtuse internal angle or a circular arc on the upper face side of the gate electrode facing the anode electrode, and forming the boundary between the upper and lower planes and side face in the cross sectional shape into an obtuse angle or a circular arc. SOLUTION: Emitters 5a having sharp tips and a gate electrode 3a on an insulating film 2 for surrounding the emitters 5a are formed on the silicon substrate 1 of an emitter electrode, and an anode electrode 7 is provided above them. The cross section of the boundary section of the side face to the gate electrode 3a facing the anode electrode 7 is formed into a circular arc or an obtuse angle, and the discharge- suppressing effect is obtained with respect to the anode electrode 7 and the emitters 5a. The planar corners of the gate electrode 3a are formed into an obtuse angle or a circular arc, the electric field is hardly concentrated, and the electric discharge from the anode electrode 7 is suppressed. A dummy electrode electrically insulated and having an acute projection is preferably formed around the gate electrode 3a, and the gate electrode 3a is protected by its electric discharge.</p> |
