Patent Publication Number: US-9852252-B2

Title: Standard cell library and methods of using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional patent application claims priority from U.S. Provisional Patent Application No. 62/040,719 filed on Aug. 22, 2014, in the U.S. Patent and Trademark Office and Korean Patent Application No. 10-2014-0167817 filed on Nov. 27, 2014, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which are herein incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     As semiconductor processing technology has developed, the sizes of transistors have been reduced and thus, more transistors are capable of being integrated into a single semiconductor device. For example, a system-on-chip (SOC), which refers to an integrated circuit (IC) integrating all components of a computer or another electronic system into a single chip, is widely used for various applications. As application performance has improved, there is a demand for semiconductor devices including more components. 
     As the sizes of transistors integrated in semiconductor devices have been reduced, the level of complexity of the process of manufacturing the semiconductor devices has become increased. That is, a defective semiconductor device that does not operate normally may be included in semiconductor devices manufactured through the semiconductor manufacturing process. A reduction in the frequency of occurrence of such a defective semiconductor device, i.e. an increase in yield, is needed. In addition, characteristics of the semiconductor device may deteriorate due to the high level of complexity of the semiconductor process. Means for improving performance of an IC included in semiconductor devices are needed by preventing or reducing the deterioration of the characteristics of the semiconductor device. 
     SUMMARY 
     Example embodiments of the inventive concepts relate to a standard cell library and methods of using the same, and more particularly, to a standard cell library stored in a non-transitory computer-readable storage medium and methods of using the same. 
     Embodiments of the inventive concepts can provide a standard cell library including information regarding a plurality of standard cells and stored on a non-transitory computer-readable storage medium. At least one of the plurality of standard cells may include a pin through which an input signal or an output signal of the at least one standard cell passes and may include first and second regions perpendicular to a stack direction. When the via is disposed in the pin, the second region may provide a resistance value of the via smaller than that of the first region. The standard cell library may further include marker information corresponding to the second region. 
     In some embodiments according to the inventive concepts, the standard cell library may further include information regarding resistance values of the candidate via locations in the first and second regions. 
     In some embodiments according to the inventive concepts, the second region may be defined in such a manner that the candidate via disposed in the second region is spaced apart from a boundary of the pin in first and second directions perpendicular to each other by at least first and second distances respectively or is spaced apart from the boundary of the pin in the first direction and a third direction that are opposite to each other by at least the first distance. 
     In some embodiments according to the inventive concepts, the pin may include a plurality of candidate points in which the via can be disposed, wherein each of the first and second regions includes some of the plurality of candidate points, and wherein the marker information corresponds to the candidate points included in the second region. 
     In some embodiments according to the inventive concepts, the plurality of candidate points may be spaced apart from each other by at least a predetermined distance. 
     In some embodiments according to the inventive concepts, the marker information may be included in the standard cell library as a virtual layer. 
     Embodiments of the inventive concepts can provide a method of using a standard cell library including information regarding a plurality of standard cells. The method may include receiving input data defining an integrated circuit (IC) including at least one of the plurality of standard cells, the at least one of the plurality of standard cells including a pin which includes first and second regions perpendicular to a stack direction, accessing a non-transitory computer-readable storage medium storing the standard cell library, the standard cell library further including marker information corresponding to the second region, and placing and routing the at least one of the plurality of standard cells included in the IC by disposing a via in the second region rather than the first region based on the marker information. 
     In some embodiments according to the inventive concepts, if the via is disposed in the second region of the pin, a resistance value of the via is smaller than if the via is placed in the first region of the pin. 
     In some embodiments according to the inventive concepts, the placing and routing the at least one of the plurality of standard cells may include analyzing a timing characteristic of the IC based on the resistance value of the via disposed in the second region. 
     In some embodiments according to the inventive concepts, the placing and routing the at least one of the plurality of standard cells may include selecting a first standard cell connected to a critical path of the IC for disposing the via in the second region rather than other standard cells included in the IC not connected to the critical path of the IC. 
     In some embodiments according to the inventive concepts, when the via is disposed in the second region of the pin, the second region may be defined in such a manner that the via is spaced apart from a boundary of the pin in first and second directions perpendicular to each other by at least first and second distances respectively or is spaced apart from the boundary of the pin in the first direction and a third direction that are opposite to each other by the at least first distance. 
     In some embodiments according to the inventive concepts, the placing and routing the at least one of the plurality of standard cells may include placing first and second patterns respectively on first and second layers to be formed after forming the pin during a semiconductor process. The via may connect the first and second patterns. The placing of the first and second patterns may include disposing the via in a region spaced apart from a boundary of the first or second pattern by more than a previously determined distance in at least two directions from among four directions perpendicular to a stack direction of the plurality of standard cells. 
     In some embodiments according to the inventive concepts, the placing and routing the at least one of the plurality of standard cells may further include disposing the via according to a grid defined in a layout of the IC. 
     In some embodiments according to the inventive concepts, the method may further include generating output data defining the IC including the placed and routed standard cells. 
     In some embodiments according to the inventive concepts, the method may be performed by a processor configured to execute a plurality of instructions. 
     Embodiments of the inventive concepts can provide a computer program product including a non-transitory computer readable storage medium having computer readable program code embodied in the computer readable storage medium that when executed by a processor causes the processor to perform operations. The operations may include receiving input data defining an integrated circuit (IC) comprising a plurality of standard cells. At least one of the plurality of standard cells may include a stack of a plurality of layers arranged in a first direction, a via connecting a first layer and a second layer of the plurality of layers, and a pin within the first layer of the plurality of layers. The pin may include first and second regions extending in a second and third direction perpendicular to the first direction. The second region may provide a lower resistance value of the via when the via is placed within the second region. The operations may also include receiving input data including marker information corresponding to the second region of the pin, determining a location for the via in the pin based on a location of the second region and a timing characteristic of the IC based on the resistance value of the via, and generating output data defining a layout of the IC. 
     In some embodiments according to the inventive concepts, the second region may be defined as an area within the pin at least a first predetermined distance from a boundary of the pin in the second direction, and at least a second predetermined distance from a boundary of the pin in the third direction. 
     In some embodiments according to the inventive concepts, determining the location for the via in the pin based on the location of the second region may include determining a plurality of candidate points within the second region in which the via can be disposed 
     In some embodiments according to the inventive concepts, determining the location for the via in the pin may further include determining a critical path of the plurality of standard cells of the IC. The location for the via in the pin may be selected in the second region of the pin if the at least one standard cell is in the critical path of the plurality of standard cells of the IC. 
     In some embodiments according to the inventive concepts, receiving input data including marker information corresponding to the second region of the standard cell may include accessing a non-transitory storage medium containing a standard cell library and generating the marker information from the standard cell library corresponding to the second region. 
     In some embodiments according to the inventive concepts, an outer boundary of the via is entirely within an outer boundary of the second region. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments of the inventive concepts will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic diagram of an example of a standard cell corresponding to information included in a standard cell library, according to example embodiments of the inventive concepts; 
         FIG. 2  is a diagram of an example of a standard cell library, according to example embodiments of the inventive concepts; 
         FIG. 3  is a diagram of various vias included in an integrated circuit (IC), according to example embodiments of the inventive concepts; 
         FIG. 4  is a diagram of an example of vias having different resistance values; 
         FIG. 5  is a graph showing a reduction effect on the resistance values of vias based on locations of the vias; 
         FIG. 6  is a schematic diagram of an example of a standard cell corresponding to information included in a standard cell library, according to example embodiments of the inventive concepts; 
         FIG. 7  is a flowchart of a method of using a standard cell library, according to example embodiments of the inventive concepts; 
         FIG. 8  is a diagram of an example of the routed standard cell of  FIG. 6 , according to example embodiments of the inventive concepts; 
         FIG. 9  is a diagram for explaining an operation of placing and routing standard cells based on marker information of  FIG. 7 , according to example embodiments of the inventive concepts; 
         FIG. 10  is a diagram for explaining an operation of placing and routing standard cells based on marker information of  FIG. 7 , according to other example embodiments of the inventive concepts; 
         FIG. 11  is a flowchart of a method of designing an IC, according to example embodiments of the inventive concepts; 
         FIG. 12  is a block diagram of a computer readable storage medium, according to example embodiments of the inventive concepts; and 
         FIG. 13  is a block diagram of a computer system, according to example embodiments of the inventive concepts. 
     
    
    
     DETAILED DESCRIPTION 
     Various example embodiments will now be described more fully with reference to the accompanying drawings in which some example embodiments are shown. Accordingly, while example embodiments are capable of various modifications and alternative forms, the example embodiments are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the example embodiments to the particular forms disclosed, but on the contrary, the example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the inventive concepts. Like numbers refer to like elements throughout the description of the figures. In the appended drawings, sizes of structures are exaggerated for clarity of the inventive concepts. 
     The terminology used herein is for the purpose of describing example embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. 
     It will be also understood that although the terms first, second, third etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element in some embodiments could be termed a second element in other embodiments without departing from the teachings of the present invention. Example embodiments of aspects of the present inventive concepts explained and illustrated herein include their complementary counterparts. 
     Moreover, example embodiments are described herein with reference to cross-sectional illustrations and/or plane illustrations that are idealized example illustrations. Accordingly, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments should not be construed as limited to the shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an etching region illustrated as a rectangle will, typically, have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of example embodiments. 
     Devices and methods of forming devices according to various embodiments described herein may be embodied in microelectronic devices such as integrated circuits, wherein a plurality of devices according to various embodiments described herein are integrated in the same microelectronic device. Accordingly, the cross-sectional view(s) illustrated herein may be replicated in two different directions, which need not be orthogonal, in the microelectronic device. Thus, a plan view of the microelectronic device that embodies devices according to various embodiments described herein may include a plurality of the devices in an array and/or in a two-dimensional pattern that is based on the functionality of the microelectronic device. 
     The devices according to various embodiments described herein may be interspersed among other devices depending on the functionality of the microelectronic device. Moreover, microelectronic devices according to various embodiments described herein may be replicated in a third direction that may be orthogonal to the two different directions, to provide three-dimensional integrated circuits. 
       FIG. 1  is a schematic diagram of an example of a standard cell  1000  corresponding to information included in a standard cell library, according to example embodiments of the inventive concepts. The standard cell library may include information regarding a plurality of standard cells and may be stored in a non-transitory computer-readable storage medium. A standard cell corresponding to the information included in the standard cell library is referred to as a unit of an integrated circuit (IC) satisfying a rule having a previously determined size of a layout thereof. For example, a height (for example, a length in a Y direction of  FIG. 1  that is a plan view of the standard cell) of a layout of a standard cell may be uniform, and a width (for example, a length in an X direction of  FIG. 1 ) of the standard cell may be different according to standard cells. The standard cell may include an input pin and an output pin, and may process an input signal received through the input pin, and may output an output signal through the output pin. 
     The IC may be defined as the plurality of standard cells. A tool for designing the IC may complete a design, i.e. a layout, of the IC by using the standard cell library including the information regarding the plurality of standard cells. The tool for designing the IC may dispose a via in a pin (i.e., an input pin or an output pin) included in the standard cell. A via may be used in an IC to connect different layers of the standard cell. In some embodiments, the via may connect the via to a pattern formed on a layer formed after forming pins of the standard cell during a semiconductor process. That is, the input signal of the standard cell or the output signal may pass through the via disposed in the pin of the standard cell. 
     As shown in  FIG. 1 , the standard cell  1000  may include two pins  1100  and  1200 . As described above, a via may be disposed in the two pins  1100  and  1200 , and thus an input signal of the standard cell  1000  or an output signal may pass through the via. Although  FIG. 1  illustrates an example in which the standard cell  1000  includes the two pins  1100  and  1200 , the standard cell  1000  corresponding to the information included in a standard cell library, according to example embodiments of the inventive concepts, is not limited thereto. The standard cell  1000  may include one pin or two or more pins. 
     According to example embodiments of the inventive concepts, the two pins  1100  and  1200  included in the standard cell  1000  may include first and second regions perpendicular to a stack direction (i.e. a direction perpendicular to X and Y directions of  FIG. 1 ) of the standard cell  1000 . For example, as shown in  FIG. 1 , the first pin  1100  may include a first region  1110  and a second region  1120 , and the second pin  1200  may include a first region  1210  and a second region  1220 . As will be described with reference to  FIGS. 3 and 4  later, when the via is disposed in the pin  1100  or  1200  of the standard cell  1000 , resistance of the via may differ according to a location of the via. In the figures described below, the stack direction of the standard cell  1000  is a Z direction, and the X and Y directions that are perpendicular to each other are perpendicular to the Z direction. 
     According to example embodiments of the inventive concepts, when the via is disposed in the pin  1100  or  1200  of the standard cell  1000 , the second region (or a low resistance region)  1120  or  1220  may provide a lower resistance of the via than that of the first region (or a high resistance region)  1110  or  1210 . That is, the via disposed in the second region  1120  or  1220  may have a lower resistance than that disposed in the first region  1110  or  1210 . According to example embodiments of the inventive concepts, the standard cell library may include marker information corresponding to the second region  1120  or  1220 . The marker information may be used by a tool for designing an IC. 
     According to example embodiments of the inventive concepts, when the via is disposed in the second region  1120  or  1220  of the pin  1100  or  1200 , the second region  1120  or  1220  may be defined in such a manner that the via may be spaced apart from a boundary of the pin  1100  or  1200  by more than a predetermined distance in at least two directions among four directions (i.e. +X, −X, +Y, and −Y directions) perpendicular to the stack direction (i.e. the direction perpendicular to X and Y directions of  FIG. 1 ) of the standard cell  1000 . For example, as shown in  FIG. 1 , in some embodiments, when the via is disposed in the second region  1120  of the first pin  1100 , the via may be spaced apart from the boundary of the first pin  1100  by more than a first distance DX and a second distance DY, respectively, in a first direction (for example, +X or −X direction) and a second direction (for example, +Y or −Y direction) that are perpendicular to each other. In some embodiments, when the via is disposed in the second region  1120  of the first pin  1100 , the via may be spaced apart from the boundary of the first pin  1100  by more than the first distance DX or the second distance DY in the first direction (for example, +X or +Y direction) and the second direction (for example, −X or −Y direction) that are opposite to each other. 
     According to example embodiments of the inventive concepts, as the second region  1120  or  1220  of the pin  1100  or  1200  is defined as described above, the first region  1110  or  1210  corresponding to the pin  1100  or  1200  excluding the second region  1120  or  1220  may include one or more sub regions. For example, as shown in  FIG. 1 , the first region  1110  of the first pin  1100  may include three sub regions  1110   a ,  1110   b , and  1110   c . Likewise, the first region  1210  of the second pin  1200  may include two sub regions  1210   a  and  1210   b.    
     According to example embodiments of the inventive concepts, the first distance DX or the second distance DY may be determined according to the resistance of the via and/or characteristics of the semiconductor process of manufacturing the IC including the standard cell. For example, the first distance DX or the second distance DY may be determined with respect to a start point of a region in which the resistance rapidly starts to decrease since the via is disposed away from the boundary of the pin  1100  or  1200 . According to example embodiments of the inventive concepts, the first distance DX or the second distance DY may be the same or different. 
       FIG. 2  is a diagram of an example of a standard cell library  100 , according to example embodiments of the inventive concepts. As described above, the standard cell library  100  according to example embodiments of the inventive concepts may include information regarding a plurality of standard cells. That is, the standard cell library  100  may include, for example, information regarding a layout function of a standard cell, timing information, power information, or layout information. As shown in  FIG. 2 , the standard cell library  100  according to example embodiments of the inventive concepts may include layout information  120  and timing information  140 . Each of the layout information  120  and the timing information  140  may include data corresponding to layout and timing characteristics of the plurality of standard cells included in the standard cell library  100 . 
     Referring to  FIG. 1 , the layout information  120  included in the standard cell library  100  according to example embodiments of the inventive concepts may include marker information  125  corresponding to the second regions  1120  and  1220  of the pins  1100  and  1200 , respectively, included in the standard cell  1000 . As described with reference to  FIG. 1 , a tool for designing an IC may use the standard cell library  100  and may place a via in the pins  1100  and  1200  based on the marker information  125  included in the standard cell library  100 . For example, the tool for designing the IC may reduce an influence of resistance generated due to the via of the IC by primarily placing the via in the second regions  1120  and  1220 . 
     The timing information  140  included in the standard cell library  100  according to example embodiments of the inventive concepts may include via resistance information  145 . The tool for designing the IC may analyze a timing characteristic with respect to a path of a signal including the via based on the via resistance information  145  included in the standard cell library  100 . Referring to  FIG. 1 , the via resistance information  145  according to example embodiments of the inventive concepts may include information regarding resistance of the via disposed in the first regions  1110  and  1210  and resistance of the via disposed in the second regions  1120  and  1220 . Accordingly, the tool for designing the IC may analyze the timing characteristic of the IC by accurately reflecting the resistance of the via due to a location of the via in the pins  1100  and  1200  of the standard cell  1000 . 
       FIG. 3  is a diagram of various vias included in an IC, according to example embodiments of the inventive concepts. The IC may be manufactured through a semiconductor process and may include a plurality of layers. For example, the semiconductor process may include a plurality of deposition operations and etching operations. The IC (or a semiconductor device including the IC) may include a plurality of layers formed through a plurality of operations. Although  FIG. 3  illustrates six layers and vias, it will be understood that the IC according to example embodiments of the inventive concepts may include more or less than 6 layers and/or vias. 
     The vias may electrically connect conductors disposed on different layers. For example, as described with reference to  FIG. 1 , the pins  1100  and  1200  included in the standard cell  1000  and patterns of other layers may be electrically connected through the vias. In addition, the vias may be used to electrically connect patterns included in layers formed after forming the pins  1100  and  1200  of the standard cell  1000  during a semiconductor process. For example, as shown in  FIG. 3 , the IC may include a plurality of layers L 1  through L 6  stacked in a Z direction. Vias V 0  through V 5  may be disposed between the layers L 1  through L 6 . In  FIG. 3 , the via V 0  may electrically connect patterns included in a pin (not shown) of a standard cell and the layer L 1 . 
     A via that connects not only a pin of a standard cell but also patterns of different layers may generate resistance between both ends of the via due to a material constituting the via or a surface contacting a pin or a pattern of a layer. For example, as shown in  FIG. 3 , the via V 1  connecting patterns included in the two layers L 1  and L 2  may generate resistance having a resistance value R_V 1  that is, for example, several tens of ohms (Ω). The resistance generated by the via may incur a delay of a signal in a path of the signal including the via. The greater the value of the resistance, the greater the delay of the signal. An increase in the delay of the signal directly influences a reduction of an operating frequency at which the IC operates, and thus a reduction in the resistance generated by the via is an important factor in improving performance of the IC. 
       FIG. 4  is a diagram of an example of vias having different resistance values.  FIG. 5  is a graph showing a reduction effect on the operating frequency of the IC as a function of resistance values of vias based on locations of the vias. In more detail,  FIG. 4  is a cross-sectional view of a via taken along a surface parallel to a stack direction (a Z direction) of an IC and perpendicular to an X or Y direction, and  FIG. 5  illustrates an increase ratio of an operating frequency due to vias having reduced resistance values. As shown in the left of  FIG. 4 , a via Vx is spaced apart from a boundary of a pattern Mx by a distance D in the X direction or in the Y direction. As shown in the right of  FIG. 4 , a via Vx′ is spaced apart from a boundary of a pattern Mx′ by a distance D′ in the X direction or in the Y direction. For example, the distance D or D′ may be several tens of nanometers, and the distance D′ may be 1.5 or 2 times the distance D. In the present example, it is assumed that the patterns Mx and Mx′ are patterns included in the same layer. 
     The level of complexity of a semiconductor process may increase due to a reduction in a size of a transistor included in the IC and a width of a pattern, and thus a via may be formed to have an incomplete shape rather than an ideal shape as shown in  FIG. 4 . For example, a material filled in the via may not be sufficiently deposited or an outer shape of the via may not be completely formed in an etching operation. A via formed in an incomplete shape may form resistance having a relatively high resistance value, and may even generate a defect in which both ends of the via are not electrically connected. 
     As shown in  FIG. 5 , an experimental result shows that a via disposed farther away from a boundary of a pattern (or a pin included in a standard cell) has a lower resistance value than that of a via disposed closer to the boundary. That is, in the example of  FIG. 4 , the via Vx′ spaced apart from the boundary of the pattern Mx′ by the distance D′ in the X direction or in the Y direction may have a lower resistance value than that of the via Vx spaced apart from the boundary of the pattern Mx by the distance D. For example, the experimental result shows that the via Vx′ may have a resistance value reduced by more than 40% compared to a resistance value of the via Vx. In more detail, referring to  FIG. 3 , as shown in  FIG. 5 , when a via is spaced relatively far apart from a boundary of a pattern in each of the layers L 1  through L 6  of the IC, an increase in an operating frequency of 8.7% to the maximum may occur due to a reduced delay of a signal owing to a lower resistance value. 
     A standard cell library according to example embodiments of the inventive concepts may include marker information corresponding to a second region defined as a region spaced apart from a boundary of a pin by more than a predetermined distance in at least two directions among four directions, thereby providing information for improving performance of an IC to a tool configured to design the IC. Accordingly, the IC designed by using the standard cell library according to example embodiments of the inventive concepts may have an improved performance, for example, a relatively high operating frequency. A yield of a semiconductor device including the IC designed by using the standard cell library according to example embodiments of the inventive concepts may also be improved, thereby reducing redundant vias for implementing the same connection for reliability of a connection in the semiconductor device. 
       FIG. 6  is a schematic diagram of an example of a standard cell  2000  corresponding to information included in a standard cell library, according to example embodiments of the inventive concepts. According to example embodiments of the inventive concepts, a pin included in a standard cell may include a limited number of points in which vias may be disposed. A tool using the standard cell library and designing an IC may place vias according to a grid  5  defined on a layout of the IC and form patterns. Accordingly, the pin included in the standard cell may include the limited number of points in which the vias may be disposed according to the grid  5 . Each of first and second regions of the pin may include some of the limited number of points. 
     As shown in  FIG. 6 , the standard cell  2000  may include a first pin  2100  and a second pin  2200 . The first pin  2100  may include a first region  2110  and a second region  2120 . The second pin  2200  may include a first region  2210  and a second region  2220 . The first region  2110  of the first pin  2100  may include two sub regions  2110   a  and  2110   b . The first region  2210  of the second pin  2200  may include two sub regions  2210   a  and  2210   b.    
     As shown in  FIG. 6 , the first pin  2100  of the standard cell  2000  may include four points P 11  through P 14  in which vias may be disposed according to a grid  5  defined in X and Y directions, and the second pin  2200  of the standard cell  2000  may include six points P 21  through P 26  in which vias may be disposed according to the grid  5 . The first region  2110  of the first pin  2100  may include the two points P 11  and P 14 . The second region  2120  of the first pin  2100  may include the two points P 12  and P 13 . The first region  2210  of the second pin  2200  may include the two points P 21  and P 26 . The second region  2220  of the second pint  2200  may include the four points P 22  through P 25 . 
     According to example embodiments of the inventive concepts, marker information included in the standard cell library may correspond to points included in a second region of a pin included in the standard cell. For example, as shown in  FIG. 6 , the marker information may include information indicating locations of the two points P 12  and P 13  included in the second region  2120  of the first point  2100  and the four points P 22  through P 25  included in the second region  2220  of the second pin  2200 . That is, according to example embodiments of the inventive concepts, the marker information may include information regarding a limited number of points instead of, or in addition to, coordinate information corresponding to circumferences of the second regions  2120  and  2220 . 
       FIG. 7  is a flowchart of a method  10  of using a standard cell library, according to example embodiments of the inventive concepts. The method  10  of using the standard cell library may be performed in a tool for designing an IC. The tool for designing the IC may be a program including a plurality of instructions executed by a processor. 
     As shown in  FIG. 7 , the method  10  of using the standard cell library may include an operation (S 12 ) of receiving input data defining the IC including standard cells. The input data may be data generated through synthesis by using the standard cell library from an abstract form of a behavior of the IC, for example, data defined in a register transfer level (RTL). For example, the input data may be a bitstream or a netlist generated when synthesizing an IC defined using, for example, a hardware description language (HDL) such as Very High Speed Integrated Circuit HDL (VHDL) or Verilog. 
     According to example embodiments of the inventive concepts, the method  10  of using the standard cell library may include an operation (S 14 ) of accessing a storage medium  50  storing the standard cell library. In some embodiments, the storage medium  50  may be non-transitory. As described above, the standard cell library according to example embodiments of the inventive concepts may include marker information that may correspond to a second region providing a low resistance value when a via is disposed in a pin of a standard cell corresponding to information included in the standard cell library. According to example embodiments of the inventive concepts, the standard cell library may be stored in the storage medium  50 , and the tool for designing the IC may be configured to access the storage medium  50  to use the standard cell library. 
     According to example embodiments of the inventive concepts, the method  10  of using the standard cell library may include an operation (S 16 ) of placing and routing standard cells based on the marker information included in the standard cell library. The input data may include information regarding standard cells included in the IC and a connection relationship between the standard cells. The method  10  of using the standard cell library may place and route the standard cells included in the IC, thereby completing a layout of the IC. 
     According to example embodiments of the inventive concepts, the operation (S 16 ) of placing and routing the standard cells included in the IC may include placing a via primarily in a second region rather than a first region based on the marker information included in the standard cell library. The via placed in the second region may have a lower resistance value than that of the via placed in the first region, and thus the via may be primarily placed in the second region in the operation (S 16 ) of placing and routing the standard cells included in the IC. In some embodiments, the via placed in the second region may improve performance of the IC and improve a yield of a semiconductor device including the IC. 
     According to example embodiments of the inventive concepts, the operation (S 16 ) of placing and routing the standard cells included in the IC may include an operation of analyzing a timing characteristic of the IC based on the resistance value of the via disposed in the second region. For example, the operation of analyzing the timing characteristic of the IC may include extracting resistance values of vias disposed in the first and second regions based on the via resistance information  145  included in the timing information  140  of the standard cell library  100  as shown in  FIG. 2  and analyzing the timing characteristic of the IC based on the extracted resistance values. As described above, the vias disposed in the first and second regions may have different resistance values, and thus the timing characteristic of the IC may be analyzed based on the via resistance information  145 . Based on the analyzed timing characteristic and a previously determined timing constraint, some of the standard cells included in the IC may be placed or routed again. 
     The operation (S 16 ) of placing and routing the standard cells included in the IC may include observing a previously determined design rule. For example, referring to  FIG. 6 , when two vias are disposed in each of the second region  2120  of the first pin  2100  and the second region  2220  of the second pin  2200 , the two vias may be spaced apart from each other by more than a distance defined in a via-to-via rule included in the design rule. 
     According to example embodiments of the inventive concepts, the method  10  of using the standard cell library may include an operation (S 18 ) of generating output data defining the IC. The output data may define the IC including the standard cells placed and routed according to the operation (S 16 ) of placing and routing the standard cells included in the IC based on the marker information included in the standard cell library. According to example embodiments of the inventive concepts, the output data may include pieces of layout information of the standard cells, i.e. a format including pattern information of the layers such as, for example, a Graphic Database System (GDS) format, or a format including external information of the standard cells like a pin of a standard cell such as, for example, a Library Exchange Format (LEF), or a Milkyway format. 
       FIG. 8  is a diagram of an example of a standard  2000 ′ cell of  FIG. 6 , routed according to example embodiments of the inventive concepts. As shown in  FIG. 8 , the standard cell  2000 ′ may include a first pin  2100 ′ and a second pin  2200 ′, and may be placed and routed in a layout of an IC according to a grid  5 ′. Two vias V_A and V_B may be respectively disposed in a second region  2120 ′ of the first pin  2100 ′ and a second region  2220 ′ of the second pin  2200 ′. The via V_A disposed in the first pin  2100 ′ may connect the first pin  2100 ′ of the standard cell  2000 ′ and a pattern W 1 . The via V_B disposed in the second pin  2200 ′ may connect the second pin  2200 ′ of the standard cell  2000 ′ and a pattern W 2 . 
     Referring to the points of  FIG. 6 , the via V_A may be primarily disposed in the second region  2120 ′, and thus the via V_A may be disposed in one of the two points P 12  and P 13 . The via V_B may be primarily disposed in the second region  2220 ′, and thus the via V_B may be disposed in one of the four points P 22  through P 25 . The vias V_A and V_B may be determined to be disposed in one of the priority candidate points P 12 , P 13 , and P 22  through P 25  in consideration of another standard cell outside the standard cell  2000 ′ or a pattern. The vias V_A and V_B may be disposed in one of priority candidate points such that the vias V_A and V_B may be spaced apart from each other by more than a predetermined distance based on a design rule, for example, a via-to-via rule. Due to these constraints, a via may be disposed not in a second region but in a first region. Marker information included in a standard cell library may correspond to priority candidate points, i.e. the points P 12  and P 13  of the first pin  2100 ′ and the points P 22  through P 25  of the second pin  2200 ′. The vias V_A and V_B may be primarily disposed in the second region rather than the first region based on the marker information. 
       FIG. 9  is a diagram for explaining the operation (S 16 ) of placing and routing standard cells based on the marker information of  FIG. 7 , according to example embodiments of the inventive concepts. A part of a plurality of standard cells included in an IC may form a critical path. The critical path may be referred to as a path of a signal influencing a timing characteristic during an operation of the IC such as, for example, a path of a signal having the longest delay time. A timing characteristic of the IC may be dependent upon a characteristic of the critical path. The critical path may include standard cells connected to the critical path and signal lines connecting the standard cells. 
     The operation (S 16 ) of placing and routing the standard cells based on the marker information of  FIG. 7  according to example embodiments of the inventive concepts may include primarily placing vias in second regions of pins included in the standard cells connected to the critical path of the IC rather than other standard cells included in the IC. For example, as shown in  FIG. 9 , in an IC including 7 standard cells C 1  through C 7 , the critical path may include four standard cells C 1 , C 4 , C 5 , and C 7  and three signal lines (bold arrows). The operation (S 16 ) of placing and routing the standard cells based on the marker information may include primarily placing vias in second regions of pins included in four cells C 1 , C 4 , C 5 , and C 7  included in (or connected to) the critical path rather than other standard cells C 2 , C 3 , and C 6 . Accordingly, the vias included in the critical path may have smaller resistance values, and reduce a delay of a signal in the critical path, thereby contributing to an improvement in the timing characteristic of the IC. 
       FIG. 10  is a diagram for explaining the operation (S 16 ) of placing and routing standard cells based on the marker information of  FIG. 7 , according to other example embodiments of the inventive concepts. As described with reference to  FIG. 3 , an IC may include vias connecting a plurality of layers and patterns included in the plurality of layers. For example, as shown in  FIG. 10 , three patterns Ma, Mb, and Mc may be disposed in different layers, a via Vab may connect the two patterns Ma and Mb, and a via Vbc may connect the two patterns Mb and Mc. 
     According to example embodiments of the inventive concepts, the operation (S 16 ) of placing and routing the standard cells of  FIG. 7  may include an operation of routing the standard cells by forming patterns included in layers formed after forming pins of the standard cells during a semiconductor process. The operation of routing the standard cells by forming the patterns may include primarily disposing vias connecting the patterns in a region spaced apart from boundaries of the patterns by more than a previously determined distance in at least two directions among four directions (+X, −X, +Y, and −Y directions of  FIG. 10 ) perpendicular to a stack direction (Z direction of  FIG. 10 ) of the standard cells rather than other regions of the patterns. 
     As shown in  FIG. 10 , the via Vab may be spaced apart from a boundary of the pattern Ma in the −X direction by a predetermined distance DX′ and may be spaced apart from the boundary of the pattern Ma in the +X direction by more than the distance DX′. The via Vab may be spaced apart from a boundary of the pattern Mb in the −Y direction by a predetermined distance DY′ and may be spaced apart from the boundary of the pattern Mb in the +Y direction by more than the distance DY′. As shown in  FIG. 10 , the Vbc may be spaced apart from the boundary of the pattern Mb in the +Y and −Y directions by more than the distance DY′. The via Vbc may be spaced apart from a boundary of the pattern Mc in the +X direction by more than the distance DX′ and may be spaced apart from the boundary of the pattern Mc in the −Y direction by more than the distance DY′. Not only vias disposed in pins included in the standard cells but also the vias disposed in the patterns included in the plurality of layers of the IC according to example embodiments of the inventive concepts may be primarily disposed to be spaced apart from boundaries of the patterns by more than a predetermined distance, and thus the vias may have small resistance values. Accordingly, a delay in a signal of a signal line including the vias may be reduced. 
       FIG. 11  is a flowchart of a method of designing an IC, according to example embodiments of the inventive concepts. The method of designing the IC may be performed by a tool configured to design the IC. The tool configured to design the IC may be a program including a plurality of instructions executed by a processor. Compared to the method ( 10 ) of using the standard cell library of  FIG. 7 , the method of designing the IC of  FIG. 10  may use a general standard cell library, i.e. a standard cell library not including marker information, and may generate marker information. 
     As shown in  FIG. 1 , the method ( 20 ) of designing the IC may include an operation (S 22 ) of receiving input data defining the IC including standard cells. For example, the input data may be a bitstream or a netlist generated when synthesizing the IC defined using an HDL such as, for example, VHDL or Verilog. The method ( 20 ) of designing the IC may include an operation (S 24 ) of accessing a storage medium  60  storing the general standard cell library. In some embodiments, the storage medium  60  may be non-transitory. The general standard cell library may include layout information and timing information of a standard cell. 
     According to example embodiments of the inventive concepts, the method ( 20 ) of designing the IC may include an operation (S 25 ) of generating the marker information from standard cells included in the IC. The operation (S 25 ) of generating the marker information may include extracting information of a pin included in each of the standard cells included in the IC based on the general standard cell library, partitioning first and second regions from the extracted information of the pin, and generating the marker information corresponding to the second region. For example, the operation (S 25 ) of generating the marker information may include partitioning the first and second regions from the information of the pin included in the standard cell based on a previously determined distance measured from a boundary of the pin included in the standard cell. The previously determined distance may be determined in advance by a designer when the method ( 20 ) of designing the IC is performed or may be defined by a design rule. 
     According to example embodiments of the inventive concepts, the method ( 20 ) of designing the IC may include an operation (S 26 ) of placing and routing the standard cells based on the generated marker information. The operation (S 26 ) of placing and routing the standard cells included in the IC may include primarily disposing a via in the second region rather than the first region based on the generated marker information. The via disposed in the second region may have a smaller resistance value than that of the via disposed in the first region, and thus the operation (S 26 ) of placing and routing the standard cells included in the IC may include primarily disposing the via in the second region. In some embodiments, primarily disposing the via in the second region may improve performance of the IC and improve a yield of a semiconductor device including the IC. 
     According to example embodiments of the inventive concepts, the method ( 20 ) of designing the IC may include an operation (S 28 ) of generating output data defining the IC. For example, the output data may have a type including layout information of the standard cells like, for example, a GDS type or may have a type including outside information of the standard cell like, for example, a LEF or Milkyway type. 
     Aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, server, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable instruction execution apparatus, create a mechanism for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     These computer program instructions may also be stored in a computer readable medium that when executed can direct a computer, server, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions when stored in the computer readable medium produce an article of manufacture including instructions which when executed, cause a computer to implement the function/act specified in the flowchart and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer, server, other programmable instruction execution apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
       FIG. 12  is a block diagram of a computer readable storage medium  200 , according to example embodiments of the inventive concepts. The computer readable storage medium  200  may include an arbitrary storage medium that may be read by a computer while the computer readable storage medium  200  is used to provide instructions and/or data to the computer. In some embodiments, the computer readable storage medium  200  may be non-transitory. Examples of the computer readable storage medium  200  may include a magnetic or optical medium such as a compact disc-read only memory (CD-ROM), a digital versatile disc-ROM (DVD-ROM), a compact disc-recordable (CD-R), a compact disc re-writable (CD-RW), a DVD-R, or a DVD-RW, a volatile or nonvolatile memory such as a random-access memory (RAM), a ROM, or a flash memory, a nonvolatile memory that may be accessed via a universal serial bus (USB) interface, and a microcelectromechanical system (MEMS). The computer readable storage medium  200  may be inserted into the computer, integrated into the computer, or may be coupled to the computer via a medium such as a network and/or a wireless link. 
     As shown in  FIG. 12 , the computer readable storage medium  200  may include a place and route program  220 , a library  240 , an analysis program  260 , and a data structure  280 . The place and route program  220  may include a plurality of instructions for performing a method of using a standard cell library or a method of designing an IC according to example embodiments of the inventive concepts. For example, the computer readable storage medium  200  may store the place and route program  220  including arbitrary instructions configured to perform partially or wholly the methods represented by the flowcharts illustrated in one or more of the above-described figures. 
     The library  240  may include information regarding a standard cell that is a unit constituting the IC. For example, the library  240  may store a standard cell library including marker information like the storage medium  50  of  FIG. 7  or may store a standard cell library that does not include marker information like the storage medium  60  of  FIG. 11 . 
     The analysis program  260  may include a plurality of instructions configured to perform a method of analyzing the IC based on data defining the IC. For example, the computer readable storage medium  200  may include the analysis program  260  including arbitrary instructions configured to perform a method of analyzing a timing characteristic of the IC based on resistance values of vias disposed in a first region (high resistance region) and a second region (low resistance region). The data structure  280  may include a storage space configured to manage data generated during a process of using the standard cell library included in the library  240 , configured to extract the marker information from a general standard cell library included in the library  240 , or configured to analyze the timing characteristic of the IC by the analysis program  260 . 
       FIG. 13  is a block diagram of a computer system  300 , according to example embodiments of the inventive concepts. As shown in  FIG. 13 , the computer system  300  may include a processor  320 , a memory  340 , and various peripheral devices  360 . The processor  320  may be connected to the memory  340  and the peripheral devices  360 . 
     The processor  320  may be configured to execute instructions for performing at least one of the afore-described methods according to the example embodiments of the inventive concepts. According to example embodiments of the inventive concepts, the processor  320  may execute an arbitrary instruction set (for example, Intel architecture (IA)-32, 64 bit extension IA-32, X86-64, PowerPC, Sparc, microprocessor without interlocked pipeline stage (MIPS), advanced reduced instruction set computer machine (ARM), or IA-64). Also, the computer system  300  may include one or more processors. 
     The processor  320  may be arbitrarily connected to the memory  340  and the peripheral devices  360 . For example, the processor  320  may be connected to the memory  340  and/or the peripheral devices  360  through various interconnections. Alternatively, one or more bridge chips may generate multi-connections between the processor  320 , the memory  340 , and the peripheral devices  360  and may be used to connect the components. 
     The memory  340  may include an arbitrary memory system. Examples of the memory  340  may include a dynamic random-access memory (DRAM), a double data rate synchronous dynamic random-access memory (DDR SDRAM), and a Rambus DRAM (RDRAM). A memory controller may be provided in order to interface with the memory  340  and/or the processor  320  may include the memory controller. The memory  340  may store the instructions for performing the method of using the standard cell library or designing the IC and data that is processed by the processor  320 . 
     The peripheral devices  360  may include arbitrary hardware devices that may be included in the computer system  300  or may be coupled to the computer system  300 , for example, a storage device and an input/output device (e.g., video hardware, audio hardware, user interface devices, or networking hardware). 
     While the inventive concepts have been particularly shown and described with reference to example embodiments thereof by using specific terms, the example embodiments and terms have merely been used to explain the inventive concepts and should not be construed as limiting the scope of the inventive concepts as defined by the claims. The example embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the inventive concepts is defined not by the detailed description of the inventive concepts but by the appended claims, and all differences within the scope will be construed as being included in the inventive concept.