| 摘要 |
PURPOSE:To microminiaturize an LSI and to improve the reliability of the LSI by selectively disposing transistors having different threshold voltages at the end of a power source line and near a noise generation source to absorb the abnormal voltage of a power source. CONSTITUTION:Field transistors are disposed at the ends 12 of power source lines 11 and at points A, B near a noise generation source to clamp a noise which reflects at the ends when the noise rises from exterior on the line 11. An aluminum field transistor can be formed by a normal technique, its breakdown is absorbed by the Vth of the transistor, the Vth is altered by controlling the dosage of ion implanting, an accelerating voltage when forming a P<+> type layer of the transistor by normal ion implanting. Since the dosage and the accelerating voltage can be altered with good controllability, the controllability of the aluminum field transistor Vth can be enhanced. |
