Integrated circuit device and method for forming the same
View Patent ↗In an integrated circuit device, element power supply lines connected to a circuit containing a plurality of cells, element ground lines connected thereto, a trunk power supply line connected to each of the element power supply lines, and a trunk ground line connected to each of the element ground lines are provided in a first wiring layer. A branch power supply line connected to the trunk power supply line and a branch ground line connected to the trunk ground line are provided in an upper wiring layer located above the first wiring layer. A wiring structure is determined based on a wiring structure equation expressing the relations among a voltage drop in the lines, the area occupied thereby, and a current consumed thereby and on a circuit characteristic equation expressing, when the circuit is subdivided while the ratio between the area of the circuit and a current consumed thereby is held constant, the relation between an area occupied by a circuit resulting from subdivision and a current consumed thereby.
1. A method for forming a wiring structure, the method comprising the steps of:
(a) determining an amount of voltage drop due to a resistance of a voltage supply line connected to a circuit portion of an integrated circuit device and a wiring structure equation representing a correlation between an area of the circuit portion and a current of the circuit portion;
(b) determining, when the circuit portion is subdivided while a ratio between the area of the circuit portion and the current of the circuit portion is maintained, a circuit characteristic equation representing a correlation between an area of each of subdivided circuit portions and a current of the subdivided circuit portion; and
(c) determining a structure of the voltage supply line such that the area of the subdivided circuit portion and the current of the subdivided circuit portion are equal to or less than an area and a current given by solutions of simultaneous equations composed of the wiring structure equation and the circuit characteristic equation.
2. The method of claim 1 , wherein the wiring structure equation satisfies Vd=a×S×I, where Vd is the amount of voltage drop, S is the area of the circuit portion, I is the current therein, and a is a coefficient.
3. The method of claim 2 , wherein the coefficient a is a constant.