An integrated circuit is a complete electronic circuit, containing transistors, diodes, resistors, and capacitors, along with their interconnecting electrical conductors, contained entirely within a single chip of silicon. These components are often interconnected to form multiple circuit components, such as gates, cells, memory units, arithmetic units, controllers, decoders, etc. An integrated circuit, such as an application specific integrated circuit (ASIC) may include bidirectional input/output (I/O) ports that are used to both send and receive data over the same set of wires. The C-MOS type integrated circuit device may include a single kind of a conductive material as gate electrodes of the N-MOS transistor and the P-MOS transistor to simplify processes for manufacturing the C-MOS type integrated circuit device. Integrated circuits are made of semiconductor material. Semiconductor material is material that has a resistance that lies between that of a conductor and an insulator. Semiconductor material is used to make electrical devices that exploit its resistive properties. Generally, an integrated circuit comprises a substrate upon which a variety of circuit components are formed wherein each of the circuit components are electrically isolated from each other. Voltage dividers are often used in integrated circuits to supply a voltage different from that of an available power source. Typically, voltage dividers in integrated circuits are designed using resistors. The most commonly utilized type of resistor in voltage dividers formed on a semiconductor substrate is the P+ poly resistor formed from polysilicon. Capacitors are critical devices in integrated circuit designs, particularly for high density memory chips such as dynamic random access memories (DRAMs). A capacitor is composed of two layers of a material that is electrically conductive brought near to one another and separated by a material that is electrically nonconductive.

Modern integrated circuits are often based on metal-oxide-semiconductor (MOS) technology. Integrated circuits based on complementary metal-oxide-semiconductor (CMOS) transistor technology are widely used in modern electronic systems. Such integrated circuits have numerous metal-oxide-semiconductor field-effect transistors (MOSFETs). Transistors in integrated circuit act as switches and can be turned on or turned off to create various logic functions. When the transistors are turned on they conduct their maximum current, when they have been turned off they conduct their minimum current, which is known as leakage current. A transistor of integrated circuit device may include a gate electrode formed on an active region of a substrate, a gate insulating layer interposed between the gate electrode and the substrate, and at least one source/drain regions formed on the active region positioned at both sides of the gate electrode. A metal oxide semiconductor field effect transistor (MOSFET) may include a gate insulating layer formed on a substrate and a gate electrode formed on the gate insulating layer. A MOS type highly-integrated integrated circuit device may include a complement-MOS (C-MOS) type device that has both an N-MOS transistor and a P-MOS transistor. Typical metal oxide semiconductor transistors are formed with a gate region between doped active regions. The doped active regions are typically designated as a source region and a drain region. The proper performance of CMOS integrated circuits is often critically dependent on the stable operation of its MOS transistors. Metal oxide semiconductor (MOS) transistors exhibit various advantages as compared to bipolar transistors. The MOS transistors are suitable for a semiconductor integrated circuit (IC) having a high integration density and a low operation voltage with low power consumption. Therefore, most semiconductor ICs employ the MOS transistors as switching elements.

An integrated circuit includes multiple layers of wiring that interconnect its electronic and circuit components. These layers made of metal, semiconductor and insulator material, each configured so that it cooperates with other layers to define circuit elements, such as buffers, memory devices, gates and routing wires. Each layer is stacked or overlaid on a prior layer and patterned to form the shapes that define devices and connect the devices into circuits. The metal layers define routing wires for connecting together various elements, including memory matrices. At least one insulator layer between adjacent metal layers insulates the metal layers from each other, and metal posts or channels between horizontal and vertical routing wires provide connection between them so signals and power can propagate through the IC. A silicon oxide layer including a thermal oxide layer may be used as a gate insulating layer. The gate electrode may include a doped polysilicon layer. Integrated circuits typically comprise a semiconductor substrate on which several component layers have been formed to produce a large number of laterally-distributed transistors and other circuit devices. Additional connection layers are formed on top of the component layers to provide interconnections among and power to the circuit devices, and input and output signal connections to the devices. Power is typically delivered to the devices by a grid of power conductors which pass through the conduction layers to the devices periodically and terminate at pads disposed on the top layer of the die. An IC chip may also contain conductive pads for providing electrical couplings of the chip to external devices, such as voltage sources and control circuits. In general, an integrated circuit comprises integrated circuit substrates, such as a silicon semiconductor substrate including a plurality of microelectronic devices therein, and interconnect systems on the integrated circuit substrate for selectively interconnecting the microelectronic devices and/or for providing power supply and/or input/output connections.

The integrated circuits may be arranged into blocks associated with a particular function.  A semiconductor integrated circuit is generally composed of a plurality of functional blocks. A semiconductor integrated circuit device such as an LSI normally comprises a plurality of functional blocks. There may be several blocks involved in only the input/output (I/O) of signals to and from another block or group of blocks. Some blocks of circuits and logic gates are used to store instantaneous state of the signals, such as registers and other memory units such as buffers, caches, etc. Some blocks have a primary purpose of manipulation of the signals using transistors, such as the logic gates and processors. There are also blocks whose only function may be the continuous monitoring and testing of the other blocks, etc. Among these functional blocks, ones having a variety of uses, such as memory blocks, are generally treated as libraries at the functional block level so that they can be used in various applications. In functional blocks, the functional blocks high in general versatility are generally libraried in functional block units so that they can be used in various applications. The functional blocks libraried in this manner are called hard macros. Aside from the hard macro cells, the functional blocks include soft macro cells, in which design content can be modified as is appropriate when the semiconductor integrated circuit is designed.

The basic purpose of constructing integrated circuits is to provide the necessary functions (e.g., data reception, data analysis, display, electrical control, etc.) for the IC embedded electronics. Generally, integrated circuits are mainly divided into two categories: logic device and memory, wherein the logic device, such as a microprocessor of a computer, is used to execute logic operations, and the memory is a semiconductor device used for storing data. To access the memory cells, addressing circuitry such as decoders, drivers and sense amplifiers are provided. In addition, a typical integrated circuit includes a clock tree which distributes one or more clock signals throughout the chip to clocked elements. A clock domain is defined as a set of all logical components (flip-flops, registers, synchronous RAM) that are clocked on the same edge of the same clock net. A primary goal of a clock tree is to minimize clock skew between clocked elements.