| 摘要 |
<p>PURPOSE:To obtain high-frequency operation of a cathode by forming a gate electrode other than the opening at a position away from the base and so reducing a parasitic capacity in between the gate electrode, a bonding pad or wiring and the base. CONSTITUTION:Insulating layers 2, 6 are formed successively on a base 1, and then a hole as the position of an emitter 4 is formed. In this case, the insulating layer 6 is so etched that it is larger in the diameter direction for the hole where the emitter 4 is positioned, and the hole diameter in the layer 6 increases gradually toward the gate electrode to be conical in form. The layer 2 is exposed in ring form on the inner side of the layer 6. Then, a high-melting-point metal is laid on the layer 2 or the layer 6, so that a gate electrode 3 is formed. In this case, the electrode 3 is formed also on the layer 2, to give an opening 5. A sacrifice layer 7 is formed in oblique direction on the base 1 to appear only on the electrode 3. And then, a high-melting-point metal-layer 10 is formed in vertical direction on the base 1. In the electrode 3, gaps in the opening 5 and other portions are controlled only by thickness of the layer 6.</p> |
