| 摘要 |
PURPOSE:To effectively apply to a bidirectional Zener diode, bidirectional thyristor required for similar characteristics particularly to bidirectional voltages by alkali etching an element containing PNP layer interposed with N type of low impurity density, and forming bilateral positive bevel structure by utilizing the difference of the etching speeds to the N type and P type layers, thereby improving the reverse blocking characteristic of both P-N junctions. CONSTITUTION:Boron is, for example, diffused from both side surfaces of an N type silicon substrate to form a P type layer, and is mechanically or chemically cut or divided to form a silicon chip having PNP structure. Then, electrodes 4 and lead wires 5 are attached to the P type layers at both sides of the chip 3. Subsequently, when the side surfaces 6 of the chip 3 are etched with aqueous solution of potassium hydroxide, the reacting velocity of the solution to the N type semiconductor is faster than that to the P type semiconductor. Accordingly, a bevel shape as shown is exhibited. Such bilateral bevel structure is formed, thereby improving the characteristics of the bidirectional Zener diode. |
