Semiconductor integrated circuit device and method for designing layout of the same having standard cells, basic cells and a protective diode cell

A semiconductor integrated circuit device including a semiconductor substrate having a logic circuit placement region, the semiconductor integrated circuit device comprising:

• a plurality of standard cells that are placed in a part of the logic circuit placement region and respectively constitute a plurality of functional blocks that realize logic functions of the semiconductor integrated circuit device;
• a plurality of basic cells that are placed in a part of regions of the logic circuit placement region in which no standard cells are placed;
• and
• at least one diode cell that has a longitudinal direction defining, a length and a direction transverse to the longitudinal direction defining a width, wherein the length is greater than the width, and wherein the standard cells, basic cells and at least one diode cell are placed along a longitudinal direction of a row of the logic circuit placement region, with the at least one diode cell placed with a length of the diode cell transverse to the longitudinal direction of the row, and the at least one diode cell is placed in at least a part of regions of the logic circuit placement region in which no standard cells and no basic cells are placed, the diode cell including a first diode that is connected between a gate electrode of a predetermined transistor and a first power supply line and a second diode that is connected between the gate electrode and a second power supply line,
• wherein the diode cell is placed in at least a part of regions between two adjacent standard cells, regions between a standard cell and a basic cell, or regions at an end portion of the logic circuit placement region.