| 摘要 |
PURPOSE:To improve the electrical reliability of a semiconductor integrated circuit device by forming semiconductor elements having different electrostatic breakdown strength, arranging these semiconductor elements in order of higher electrostatic breakdown strength and constituting an electrostatic breakdown preventive circuit. CONSTITUTION:An electrostatic breakdown preventive circuit II is interposed between an external input terminal BP and an input step circuit I. The circuit II is constituted by a MISFET Q1 having a high threshold and high electrostatic breakdown strength and a MISFET Q2 having threshold voltage lower than the MISFET Q1 and electrostatic breakdown strength lower than the MISFET Q1. The circuit II is also constituted by a resistor R1 constituted by a semiconductor region having high electrostatic breakdown strength and a resistor element R2 constituted by a semiconductor region having low electrostatic breakdown strength. Consequently, excess voltage generating electrostatic breakdown can be lowered to a predetermined voltage level by stages. Accordingly, the concentration of excess currents to one semiconductor element in semiconductor elements constituting the circuit II can be prevent, thus obviating the breakdown of the circuit II. |
