Patent Publication Number: US-11042686-B2

Title: Integrated circuit including standard cells overlapping each other and method of generating layout of the integrated circuit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/933,958, filed on Mar. 23, 2018, which claims the benefit of Korean Patent Application Nos. 10-2017-0075016, filed on Jun. 14, 2017 and 10-2017-0121869, filed on Sep. 21, 2017, in the Korean Intellectual Property Office, the disclosures of each of which are incorporated herein in their entirety by reference. 
    
    
     BACKGROUND 
     Inventive concepts relates to an integrated circuit, and more particularly, to an integrated circuit including a standard cell and a method of generating the layout of the integrated circuit. 
     With the miniaturization of semiconductor processes, the size of a standard cell included in an integrated circuit may be decreased. The decreased size of a standard cell may lead to an increase in a mutual influence between adjacent standard cells. To prevent or reduce the mutual influence from increasing, a structure, e.g., a diffusion break separating standard cells from each other, may be inserted between the standard cells. Meanwhile, a standard cell may have an unnecessary or undesirable space in particular layers according to the structure thereof. Such a wasted space cancels out the decrease in size of standard cells and may thus restrict an increase in the degree of integration of an integrated circuit. 
     SUMMARY 
     Inventive concepts provides an integrated circuit including standard cells overlapping each other and a method of generating the layout of the integrated circuit. 
     According to some example embodiments of inventive concepts, there is provided an integrated circuit including a plurality of standard cells each including a front-end-of-line (FEOL) region and a back-end-of-line (BEOL) region on the FEOL region, the FEOL region including at least one gate line extending in a first horizontal direction. A BEOL region of a first standard cell among the plurality of standard cells may include an eaves section not overlapping an FEOL region of the first standard cell in a vertical direction, the eaves section protruding in a second horizontal direction perpendicular to the first horizontal direction. 
     According to some example embodiments of inventive concepts, there is provided an integrated circuit including a plurality of first standard cells each including a first FEOL region and a first BEOL region on the first FEOL region, the first FEOL region including at least one gate line extending in a first horizontal direction, the first standard cells being consecutively placed in a second horizontal direction perpendicular to the first horizontal direction. The first BEOL region of each of the first standard cells may overlap, in a vertical direction, at least part of a first FEOL region of another first standard cell adjacent in the second horizontal direction. 
     According to some example embodiments of inventive concepts, there is provided a computer implemented method of generating a layout of an integrated circuit. The computer implemented method including accessing a standard cell library defining a plurality of standard cells each including an FEOL region and a BEOL region on the FEOL region, the FEOL region including at least one gate line extending in a first horizontal direction; and placing a standard cell based on the standard cell library. The placing of the standard cell may include placing a second standard cell to be adjacent to a first standard cell in a second horizontal direction perpendicular to the first horizontal direction such that an eaves section of a BEOL region of the first standard cell overlaps a step section of an FEOL region of the second standard cell in a vertical direction, the eaves section protruding in the second horizontal direction, the step section protruding in a direction antiparallel to the second horizontal direction. 
     According to yet another aspect of inventive concepts, there is provided a computer implemented method of generating a standard cell library defining a plurality of standard cells for generating a layout of an integrated circuit. The computer implemented method includes receiving an input library defining a first standard cell including a first FEOL region and a first BEOL region on the first FEOL region, the first FEOL region including at least one gate line extending in a first horizontal direction and having double diffusion breaks formed at respective opposite sides thereof facing each other in a second horizontal direction perpendicular to the first horizontal direction to extend in the first horizontal direction; and generating an output library defining a second standard cell providing the same function as the first standard cell, the second standard cell including a second FEOL region and a second BEOL region on the second FEOL region, the second FEOL region having single diffusion breaks formed at respective opposite sides thereof facing each other in the second horizontal direction to extend in the first horizontal direction. The output library may define an eaves section of the second BEOL region and a step section of the second FEOL region, the eaves section protruding in the second horizontal direction, the step section protruding in direction antiparallel to the second horizontal direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of 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 diagram of standard cells according to an example embodiment of inventive concepts; 
         FIGS. 2A through 2E  are diagrams of some standard cells included in an integrated circuit, according to an example embodiment of inventive concepts; 
         FIG. 3  is a schematic diagram of part of an integrated circuit, according to an example embodiment of inventive concepts; 
         FIG. 4  is a flowchart of a method of fabricating an integrated circuit including a plurality of standard cells, according to an example embodiment of inventive concepts; 
         FIGS. 5A and 5B  are diagrams of examples of standard cells defined by a standard cell library shown in  FIG. 4 , according to an example embodiment of inventive concepts; 
         FIG. 6  is a diagram of other examples of standard cells defined by the standard cell library shown in  FIG. 4 , according to an example embodiment of inventive concepts; 
         FIG. 7  is a diagram of an example of a standard cell defined by a standard cell library, according to an example embodiment of inventive concepts; 
         FIGS. 8A and 8B  are diagrams of a method of generating a layout of an integrated circuit, according to an example embodiment of inventive concepts; 
         FIGS. 9A through 9C  are diagrams of a method of generating a layout of an integrated circuit, according to another embodiment of inventive concepts; 
         FIGS. 10A and 10B  are diagrams of a method of generating a layout of an integrated circuit, according to a further embodiment of inventive concepts; 
         FIGS. 11A and 11B  are diagrams of a method of generating a layout of an integrated circuit, according to yet another embodiment of inventive concepts; 
         FIG. 12  is a flowchart of a method of generating a standard cell library including a standard cell having an orientation, according to an example embodiment of inventive concepts; 
         FIGS. 13A and 13B  are diagrams of a method of generating a standard cell having an orientation, according to an example embodiment of inventive concepts; 
         FIG. 14  is a flowchart of a method of generating a standard cell having an orientation, according to another embodiment of inventive concepts; 
         FIGS. 15A and 15B  are diagrams of a method of generating a standard cell having an orientation, according to still another embodiment of inventive concepts; 
         FIGS. 16A and 16B  are diagrams of a method of generating a standard cell having an orientation, according to yet another embodiment of inventive concepts; 
         FIGS. 17A and 17B  are diagrams of a method of generating a standard cell having an orientation, according to a further embodiment of inventive concepts; 
         FIG. 18  is a diagram of a method of verifying an integrated circuit including standard cells having an orientation, according to an example embodiment of inventive concepts; 
         FIG. 19  is a block diagram of a system-on-chip (SoC) according to an example embodiment of inventive concepts; and 
         FIG. 20  is a block diagram of a computing system including memory storing a program according to an example embodiment of inventive concepts. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of inventive concepts will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a diagram of standard cells according to an example embodiment of inventive concepts. In detail, first through third standard cells C 11 , C 12 , and C 13  are inverters having an input pin A and an output pin Y. A plan view of the first through third standard cells C 11  through C 13  on a plane formed of an X-axis and a Y-axis is shown in the upper portion of  FIG. 1 . A side view, e.g. a cross-sectional view, of the first through third standard cells C 11  through C 13  in a Y-axis direction is shown in the lower portion of  FIG. 1 . Hereinafter, a plane formed of the X- and Y-axes may be referred to as a horizontal plane; elements placed in a +Z direction as compared with other elements may be construed as being on or above the other elements; and elements placed in a −Z direction as compared with other elements may be construed as being below or under the other elements. An area of a particular object may refer to a space occupied by the object on a surface parallel with a horizontal plane. 
     A standard cell is a layout unit included in an integrated circuit. An integrated circuit may include a plurality of various standard cells. Standard cells may have a structure complying with specific, (or alternatively predetermined) specifications. For example, as shown in  FIG. 1 , the first through third standard cells C 11  through C 13  may have a fixed height, e.g. a fixed length in the Y-axis direction, and may include a pair of power rails VDD and GND to which power supply voltages may respectively be applied. The power rails VDD and GND extend in the X-axis direction to be parallel with each other and separated from each other in the Y-axis direction. The first through third standard cells C 11  through C 13  may also include at least one gate line which extends in the Y-axis direction (or a first horizontal direction) and at least one active region and at least one fin which extend in the X-axis direction (or a second horizontal direction). An active region may include a semiconductor, such as Si or Ge, or a compound semiconductor, such as SiGe, SiC, GaAs, InAs, or InP, and may include a conductive region such as an impurity-doped well and/or an impurity-doped structure. A gate line may include a work function metal layer and a gap fill metal film. For example, a work function metal layer may include at least one metal among Ti, W, Ru, Nb, Mo, Hf, Ni, Co, Pt, Yb, Tb, Dy, Er, and Pd, and a gap fill metal film may include a W film and/or an Al film. Gate lines may have a stack structure of TiAlC/TiN/W, a stack structure of TiN/TaN/TiAlC/TiN/W, and/or a stack structure of TiN/TaN/TiN/TiAlC/TiN/W. Although a fin on an active region is not illustrated in the drawings for convenience&#39;s sake, the embodiments of inventive concepts should be construed as applying to a standard cell including a fin field effect transistor (FinFET) as well as a standard cell including a planar transistor. 
     Referring to  FIG. 1 , the first through third standard cells C 11  through C 13  may include a diffusion break as a structure for decreasing a mutual influence with another adjacent standard cell when they are placed in an integrated circuit. A diffusion break may separate active regions or diffusion regions between adjacent standard cells. For example, as shown in  FIG. 1 , when the first through third standard cells C 11  through C 13  include a FinFET formed by at least one fin, a diffusion break may separate fins from each other between adjacent standard cells. Differently than shown in  FIG. 1 , when a standard cell includes a planar transistor, a diffusion break may remove at least part of a diffusion region and/or an active region, thereby separating diffusion regions between adjacent standard cells. 
     A diffusion break may include a double diffusion break (DDB) and/or a single diffusion break (SDB) according to a structure. For example, a DDB may be formed below two adjacent gate lines or at least three adjacent gate lines. The DDB may have a width, i.e., an X-axis direction length, of about at least 1 contacted poly pitch (CPP) and may extend in the Y-axis direction. An SDB may be formed below a single gate line or in a region from which a single gate line has been removed and may extend in the Y-axis direction. Accordingly, the DDB may separate adjacent standard cells by at least 1 CPP, while the SDB may allow adjacent standard cells to be continuously placed. 
     As shown in  FIG. 1 , the first through third standard cells C 11  through C 13  may include front-end-of-line (FEOL) regions FR 11 , FR 12 , and FR 13 , respectively, formed using an FEOL process and back-end-of-line (BEOL) regions BR 11 , BR 12 , and BR 13 , respectively, formed using a BEOL process. The BEOL regions BR 11 , BR 12 , and BR 13  may be provided above the FEOL regions FR 11 , FR 12 , and FR 13 , respectively. For example, an FEOL region in a standard cell may include a substrate, an active region, a fin, and a contact structure. A transistor, a diffusion break, etc. may be formed in, e.g. within, the FEOL region. A BEOL region in a standard cell may include a via and a metal layer. An input pin and an output pin of the standard cell and interconnection for internal signals may be formed in the BEOL region. Although a contact structure connected to a gate line and fins may be formed using a middle-of-line (MOL) process separately from the FEOL process and the BEOL process, herein a contact structure is understood as being included in an FEOL region. In the drawing, a via V 0  connecting a contact structure with a pattern of a first metal layer M 1  is illustrated on the pattern of the first metal layer M 1  for convenience&#39;s sake, but the via V 0  is may be understood as being between the contact structure and the first metal layer M 1 . 
     A DDB may be advantageous in terms of fabricating an integrated circuit by resolving some issues with semiconductor processes but may provide lower spatial efficiency than an SDB. While an SDB may provide higher spatial efficiency than a DDB, the SDB may cause some issues with semiconductor processes and/or may cause the degradation of performance of a standard cell. For example, as shown in  FIG. 1 , the first standard cell C 11  may include DDB regions DR 11   a  and DR 11   b  extending in the Y-axis direction with a width of ½ CPP at respective opposite sides facing each other in the X-axis direction such that DDBs may be formed together with adjacent standard cells. The second standard cell C 12  may include SDB regions SR 12   a  and SR 12   b  extending at a position of a gate line in the Y-axis direction at respective opposite sides facing each other in the X-axis direction such that SDBs may be formed together with adjacent standard cells. Accordingly, the first standard cell C 11  may have a width (i.e., an X-axis direction length) of 3 CPP and the second standard cell C 12  may have a width of 2 CPP. 
     As shown in  FIG. 1 , in the case of the second standard cell C 12 , the output pin Y may be shifted in a −X direction, e.g. in a direction antiparallel to the +X direction, compared to the first standard cell C 11 , and therefore, the input pin A may also be shifted in the −X direction. A contact structure (or a gate contact) CB 12  may extend in the X-axis direction to connect the input pin A with a gate line and may be referred to as an offset contact structure. The contact structure CB 12  may have a specific (or, alternatively, predetermined) length in the Y-axis direction, and therefore, the number of fins in an active region may be decreased compared to the first standard cell C 11  so that a distance between fins around the contact CB 12  and a contact structure (or an active contact structure) connected to the fins may be ensured. In other words, while the first standard cell C 11  may include a total of six fins F 11  through F 16  in an active region, the second standard cell C 12  may include a total of four fins F 11 , F 12 , F 15 , and F 16  in an active region. Due to the decreased number of fins, the second standard cell C 12  may have different characteristics than the first standard cell C 11 . 
     According to some example embodiments of inventive concepts, a standard cell may include an eaves section protruding in the X-axis direction in a BEOL region and/or a step section protruding in the X-axis direction in an FEOL region. For example, the third standard cell C 13  may include an eaves section (marked with “┌”) of the BEOL region BR 13  and a step section (marked with “┘”) of the FEOL region FR 13 . The eaves section (┌) and the step section (┘) of the third standard cell C 13  may have a length D in the X-axis direction. Accordingly, the third standard cell C 13  may include SDB regions SR 13   a  and SR 13   b  while having the same patterns as the first standard cell C 11  including the DDB regions DR 11   a  and DR 11   b.    
     In some example embodiments, an eaves section of a standard cell may include the first metal layer M 1  and upper layers thereof. For example, a BEOL region including the via V 0  and upper layers thereof has a protruding eaves section in the embodiments. However, inventive concepts are not limited thereto. An eaves section may include the first metal layer M 1  and upper layers thereof and the via V 0  may be in a planar boundary of an FEOL region and may be included in a step section. 
     As described with reference to  FIG. 2A  and other drawings below, the eaves section (┌) of the third standard cell C 13  may overlap a step section of an adjacent standard cell in a Z-axis direction, e.g., a vertical direction. Standard cells placed in such a manner may provide increased spatial efficiency and may substantially have the same characteristics as a standard cell (e.g., the first standard cell C 11 ) including a DDB region. In other words, standard cells may have an orientation according to directions in which an eaves section and a step section protrude, and standard cells having the same orientation may be consecutively placed. In addition, the third standard cell C 13  may be derived, e.g. easily derived, from the first standard cell C 11 , as shown in  FIG. 1 , and therefore, standard cells supporting an SDB may be generated, e.g. easily generated, from standard cells supporting a DDB which have been developed and verified at the initial operational stage of semiconductor processes, as described with reference to  FIG. 12  and other drawings below. The increased spatial efficiency may reduce chip size, which may increase the number of available integrated circuits produced on a given substrate. The increased spatial efficiency may increase a manufacturing yield of the integrated circuit. The increased spatial efficiency may reduce a unit cost of manufacturing the integrated circuit. 
       FIGS. 2A through 2E  are diagrams of some standard cells included in an integrated circuit, according to an example embodiment of inventive concepts. In detail,  FIGS. 2A through 2E  are cross-sectional views of standard cells, taken along the plane formed of the X-axis and the Z-axis, in an integrated circuit. As described above with reference to  FIG. 1 , “┌” or “¬” marks an eaves section of a BEOL region and “┘” or “└” marks a step section of an FEOL region. 
     Referring to  FIG. 2A , standard cells may be placed such that an eaves section of a standard cell overlaps a step section of an adjacent standard cell in the Z-axis direction (or the vertical direction). For example, as shown in  FIG. 2A , an eaves section (┌) of a first standard cell C 21   a  may overlap a step section (┘) of a second standard cell C 22   a  in the Z-axis direction and an eaves section (┌) of the second standard cell C 22   a  may overlap a step section (┘) of a third standard cell C 23   a  in the Z-axis direction. As shown in  FIG. 2A , for the placement of a succession of standard cells, each standard cell may have an eaves section (┌) and a step section (┘) respectively protruding in antiparallel, e.g. opposite, directions. Herein antiparallel may mean parallel but oriented in opposite directions. For example, the first through third standard cells C 21   a  through C 23   a  may have an eaves section (┌) protruding in a +X direction and a step section (┘) protruding in a −X direction. Herein a standard cell (e.g., C 21   a , C 22   a , or C 23   a ) having an eaves section protruding in the +X direction and a step section protruding in the −X direction is understood as having a +X orientation and that a standard cell (e.g., C 23   b  in  FIG. 2B ) having an eaves section protruding in the −X direction and a step section protruding in the +X direction is understood as having a −X orientation. 
     In some embodiments, an SDB may be formed between FEOL regions of respective standard cells placed with the +X orientation. For example, as shown in  FIG. 2A , an SDB may be formed between an FEOL region of the first standard cell C 21   a  and an FEOL region of the second standard cell C 22   a , and the SDB may extend in the Y-axis direction. Meanwhile, as shown in the FEOL regions of the second and third standard cells C 22   a  and C 23   a , active regions and/or fins of adjacent standard cells may be connected with each other with no diffusion break therebetween. Although an SDB is not shown at a boundary of a standard cell or between FEOL regions of adjacent standard cells in the drawings, an SDB may be understood as being formed at a border between FEOL regions of adjacent standard cells. 
     Referring to  FIG. 2B , a standard cell changing an orientation may be between standard cells having different orientations in some embodiments. For example, a second standard cell C 22   b  may be between a first standard cell C 21   b  having the +X orientation and the third standard cell C 23   b  having the −X orientation. The second standard cell C 22   b  may have a step section (┘) protruding in the −X direction and a step section (└) protruding in the +X direction and the step sections (┘, └) of the second standard cell C 22   b  may respectively overlap an eaves section (┌) of the first standard cell C 21   b  and an eaves section (¬) of the third standard cell C 23   b  in the Z-axis direction. Accordingly, the orientation of standard cells may be changed through the second standard cell C 22   b . A standard cell like the second standard cell C 22   b  which changes the orientation of standard cells may be understood as having a ±X orientation and is referred to as a convergence cell. The second standard cell C 22   b  may provide an output signal by processing an input signal like a third standard cell C 53  shown in  FIG. 5B  and may also be a filler cell like fourth and fifth standard cells C 54  and C 55  shown in  FIG. 5B . 
     Referring to  FIG. 2C , a DDB may be formed at a portion where the orientation of standard cells is changed in some embodiments. For example, a first standard cell C 21   c  and a second standard cell C 22   c  may be placed such that an eaves section (┌) of the first standard cell C 21   c  having the +X orientation is adjacent to an eaves section (¬) of the second standard cell C 22   c  having the −X orientation. Accordingly, a DDB DB 21   c  may be below the eaves sections (¬, ┌) of the first and second standard cells C 21   c  and C 22   c , i.e., an empty space between FEOL regions of the first and second standard cells C 21   c  and C 22   c . Although BEOL regions of the first and second standard cells C 21   c  and C 22   c  are shown as being in contact, e.g. in direct contact, with each other in  FIG. 2C , BEOL regions of respective standard cells having different orientations, e.g. extending in directions antiparallel to one another, may be separated from each other such that a distance between FEOL regions of the respective standard cells is a width (e.g., 1 CPP) of a DDB. 
     Referring to  FIG. 2D , standard cells may be placed such that standard cells respectively having step sections protruding in different directions, respectively, are in contact with each other in some embodiments. For example, as shown in  FIG. 2D , a first standard cell C 21   d  and a second standard cell C 22   d  may be placed such that a step section (└) of the first standard cell C 21   d  having the −X orientation is adjacent to a step section (┘) of the second standard cell C 22   d  having the +X orientation. Accordingly, a space B 21   d  may be formed between BEOL regions of the first and second standard cells C 21   d  and C 22   d , i.e., above FEOL regions (└, ┘) of the first and second standard cells C 21   d  and C 22   d , and the space B 21   d  in a BEOL region may include patterns connecting power rails of the first and second standard cells C 21   d  and C 22   d.    
     Referring to  FIG. 2E , similarly to the embodiments illustrated in  FIG. 2B , a standard cell changing an orientation may be between standard cells having different orientations in some embodiments. For example, a second standard cell C 22   e  may be between a first standard cell C 21   e  having the −X orientation and a third standard cell C 23   e  having the +X orientation. The second standard cell C 22   e  may have an eaves section (¬) protruding in the −X direction and an eaves section (┌) protruding in the +X direction, and the eaves sections (¬, ┌) of the second standard cell C 22   e  may respectively overlap a step section (└) of the first standard cell C 21   e  and a step section (┘) of the third standard cell C 23   e  in the Z-axis direction. Accordingly, the orientation of standard cells may be changed through the second standard cell C 22   e . The second standard cell C 22   e  may be assumed to have the ±X orientation and may be referred to as a divergence cell. Similarly to the second standard cell C 22   b  shown in  FIG. 2B , the second standard cell C 22   e  may provide an output signal by processing an input signal and may also be a filler cell. 
       FIG. 3  is a schematic diagram of part of an integrated circuit  30  shown in plan view, according to an example embodiment of inventive concepts. As described above with reference to  FIG. 1 , the integrated circuit  30  may include a plurality of standard cells, and the standard cells may have a fixed height, e.g., fixed length in the Y-axis direction. As described with reference to  FIG. 3  below, the integrated circuit  30  may include a plurality of standard cells which have the same orientation and are consecutively placed, thereby preventing or reducing the likelihood of performance degradation of the standard cells and providing increased spatial efficiency. The increased spatial efficiency may reduce chip size, which may increase the number of available integrated circuits produced on a given substrate. The increased spatial efficiency may increase a manufacturing yield of the integrated circuit. The increased spatial efficiency may reduce a unit cost of manufacturing the integrated circuit. 
     In some example embodiments, the integrated circuit  30  may include consecutively-placed standard cells having the same orientation. For example, as shown in  FIG. 3 , standard cells placed in a first row R 31  may have the +X orientation (marked with “→”) and may have an eaves section protruding in the +X direction and a step section protruding in the −X direction, that is, a direction antiparallel to the +X direction. Accordingly, a BEOL region (e.g., an eaves section) of one standard cell may overlap, in the Z-axis direction, an FEOL region (e.g., a step section) of another standard cell adjacent in the +X direction in the first row R 31 . Similarly, standard cells placed in a third row R 33  may have the −X orientation (marked with “←”) and may have an eaves section protruding in the −X direction and a step section protruding in the +X direction. Accordingly, a BEOL region (e.g., an eaves section) of one standard cell may overlap, in the Z-axis direction, an FEOL region (e.g., a step section) of another standard cell adjacent in the −X direction in the third row R 33 . 
     In some example embodiments, the integrated circuit  30  may include standard cells having different orientations in one row. For example, as shown in  FIG. 3 , the integrated circuit  30  may include a series of standard cells having the −X orientation (←) and a series of standard cells having the +X orientation (→) in a second row R 32 , the −X orientation and the +X orientation being antiparallel to one another. The integrated circuit  30  may include a standard cell (e.g., C 22   e  in  FIG. 2E ), which changes an orientation, at a spot X 31  where standard cells having different orientations meet and may include patterns connecting power rails of adjacent standard cells. Similarly, standard cells having the −X orientation (←) may be between standard cells having the +X orientation (→) in a fourth row R 34 . 
       FIG. 4  is a flowchart of a method of fabricating an integrated circuit including a plurality of standard cells, according to an example embodiment of inventive concepts. 
     A standard cell library D 42  may include information about a plurality of standard cells, e.g., function information, characteristic information, and layout information. As shown in  FIG. 4 , the standard cell library D 42  may define a first group D 42 _ 1  including standard cells having the +X orientation, a second group D 42 _ 2  including standard cells having the −X orientation, and a third group D 42 _ 3  including standard cells having the ±X orientation. 
     Logic synthesis may be performed to generate netlist data D 43  from register transfer level (RTL) data D 41  in operation S 410 . For example, a semiconductor design tool (e.g., a logic synthesis tool) may perform logic synthesis based on the RTL data D 41  written in hardware description languages (HDLs), such as very high speed integrated circuit (VHSIC) HDL (VHDL) and/or Verilog, referring to the standard cell library D 42 , thereby generating the netlist data D 43  including a bitstream or a netlist. The standard cell library D 42  may define a plurality of standard cells that provide the same function and have different orientations and/or may define a plurality of standard cells that have the same function and orientation and different boundary structures. Accordingly, standard cells may provide the same function while having different characteristics and the standard cell library D 42  may include information about the characteristics of the standard cells. Referring to such information, standard cells may be included in an integrated circuit during logic synthesis. 
     Placement and routing (P&amp;R) may be performed to generate layout data D 44  from the netlist data D 43  in operation S 420 . As shown in  FIG. 4 , P&amp;R may include a plurality of operations S 421 , S 422 , and S 423 . 
     Standard cells may be placed in operation S 421 . For example, a semiconductor design tool (e.g., a P&amp;R tool) may place a plurality of standard cells based on the netlist data D 41 , referring to the standard cell library D 42 . As described above, the standard cells may have an orientation, and therefore, the semiconductor design tool may place the standard cells based on the orientation of each standard cell. For example, the semiconductor design tool may place standard cells based on the orientation of each standard cell such that an FEOL region of a standard cell overlaps a BEOL region of an adjacent standard cell in the vertical direction. In addition, after the standard cells are placed according to the boundary structures thereof defined in the standard cell library D 42 , a diffusion break, e.g., a DDB or an SDB, may be placed between adjacent standard cells. 
     Interconnections may be created in operation S 422 . An interconnection may electrically connect an output pin with an input pin in a standard cell and may include, for example, at least one contact structure or via and at least one conductive pattern. The standard cells may be routed by creating the interconnections. For example, referring to  FIG. 2D , interconnections connecting power rails of the first and second standard cells C 21   d  and C 22   d  may be formed in the space B 21   d  in the BEOL region. 
     The layout data D 44  may be generated in operation S 423 . The layout data D 44  may be in a format, e.g., Graphics Database System II (GDSII), and may include geometric information of standard cells and interconnections. 
     Optical proximity correction (OPC) may be performed in operation S 430 . The OPC may refer to an operation of forming a pattern in a specific, e.g. desired, shape by correcting distortion, such as diffraction, caused by the characteristics of light in photolithography included in semiconductor processes for fabricating an integrated circuit. A pattern on a mask may be determined by applying the OPC to the layout data D 44 . In some example embodiments, the layout of an integrated circuit may be restrictively changed in operation S 430 . For example, at least one operation included in any one of methods of generating a layout of an integrated circuit described with reference to  FIGS. 8A through 11B  below may be included in operation S 420  in some embodiments or may be included in operation S 430  in other example embodiments. Restrictively changing the integrated circuit in operation S 430  may be a post-treatment for improving, e.g. optimizing, the structure of the integrated circuit and may be referred to as design polishing. 
     A mask may be manufactured in operation S 440 . For example, patterns on a mask may be defined by applying the OPC to the layout data D 30 , and at least one mask (or photomask) for forming patterns on each of a plurality of layers may be manufactured. The at least one mask may include the patterns corresponding to the layout data D 30 . 
     An integrated circuit may be fabricated in operation S 450 . For example, the integrated circuit may be fabricated by patterning the layers using the at least one mask manufactured in operation S 440 . As shown in  FIG. 4 , operation S 450  may include operations S 451  and S 452 . 
     An FEOL process may be performed in operation S 451 . FEOL processing may refer to a process of forming individual elements, e.g., a transistor, a capacitor, and a resistor, on a substrate during the fabrication of the integrated circuit. For example, FEOL processing may include wafer planarization and cleaning, formation of a trench, formation of a well, formation of a gate line, and/or formation of a source and a drain. FEOL processing may include photolithography, deposition, dry etching, cleaning, ion implantation, and/or other unit processes; however, inventive concepts are not limited thereto. Photolithography may include patterning a substrate using at least one mask manufactured in operation S 440 . Here, a portion formed using the FEOL process may be referred to as an FEOL region and may include, for example, an active region, a diffusion region, a gate line, and a contact structure. 
     A BEOL process may be performed in operation S 452 . BEOL processing may refer to a process of interconnecting individual elements, e.g., a transistor, a capacitor, and a resistor, during the fabrication of the integrated circuit. For example, BEOL may include silicidation of gate, source, and drain regions, addition of a dielectric, planarization, formation of a hole, addition of a metal layer, formation of a via, and formation of a passivation layer. BEOL processing may include photolithography, deposition, etching, planarization, electroplating, etc.; however, inventive concepts are not limited thereto. Photolithography may include patterning a substrate using at least one mask manufactured in operation S 440 . Here, a portion formed using the BEOL process may be referred to as a BEOL region and may include, for example, a via and a metal layer pattern. Thereafter, the integrated circuit may be packaged into a semiconductor package and used as a component of various applications. 
       FIGS. 5A and 5B  are diagrams of examples of standard cells defined by the standard cell library D 42  shown in  FIG. 4 , according to an example embodiment of inventive concepts. In detail,  FIG. 5A  shows standard cells respectively included in the first and second groups D 42 _ 1  and D 42 _ 2  of the standard cell library D 42  and  FIG. 5B  shows standard cells included in the third group D 42 _ 3  of the standard cell library D 42 . As described above with reference to  FIG. 4 , the first group D 42 _ 1  may include standard cells having the +X orientation, the second group D 42 _ 2  may include standard cells having the −X orientation, and the third group D 42 _ 3  may include standard cells having the ±X orientation. Hereinafter,  FIGS. 5A and 5B  are described with reference to  FIG. 4 . 
     Referring to  FIG. 5A , the standard cell library D 42  may define standard cells that provide the same inverter function and have different orientations. For example, as shown in  FIG. 5A , a first standard cell C 51  and a second standard cell C 52  may provide the same function as an inverter including the input pin A and the output pin Y, but may have different orientations. In other words, the first standard cell C 51  may be included in the first group D 42 _ 1  of the standard cell library D 42  and may have an eaves section (┌) protruding in the +X direction in a BEOL region BR 51  and a step section (┘) protruding in the −X direction in an FEOL region FR 51 . The second standard cell C 52  may be included in the second group D 42 _ 2  of the standard cell library D 42  and may have an eaves section (¬) protruding in the −X direction in a BEOL region BR 52  and a step section (└) protruding in the +X direction in an FEOL region FR 52 . 
     The standard cell library D 42  may classify standard cells that provide the same function but have different structures into a same functional group. Standard cells in one same functional group may have different orientations, may have different boundary structures, as described with reference to  FIG. 6  below, and/or may have different pin placements, as described with reference to  FIG. 10B  below. Standard cells having different orientations in one same functional group may be symmetrical. For example, as shown in  FIG. 5A , the first and second standard cells C 51  and C 52  may be symmetrical with respect to an axis parallel with the Y-axis. 
     Referring to  FIG. 5B , the standard cell library D 42  may define standard cells included in the third group D 42 _ 3 . For example, a third standard cell C 53  may be an inverter having a higher driving strength than the first and second standard cells C 51  and C 52  shown in  FIG. 5A . Fourth and fifth standard cells C 54  and C 55  may be filler cells and may be placed in a space remaining after standard cells having a unique function, e.g., a function of generating an output signal by processing an input signal, are placed. As shown in  FIG. 5B , standard cells which have the ±X orientation and have an FEOL region larger than a BEOL region may have relatively fewer input and output pins or relatively fewer metal layer patterns compared to the number of gate lines. The standard cells having the ±X orientation and an FEOL region larger than a BEOL region may include a function cell having a relatively higher driving strength and a non-function cell. Although, similarly to the second standard cell C 22   b  shown in  FIG. 2B , standard cells having an FEOL region larger than a BEOL region are illustrated in  FIG. 5B , the third group D 42 _ 3  may also be understood as including standard cells having a BEOL region larger than an FEOL region, such as the second standard cell C 22   e  shown in  FIG. 2E  and a seventh standard cell C 97  shown in  FIG. 9C . 
       FIG. 6  is a diagram of other examples of standard cells defined by the standard cell library D 42  shown in  FIG. 4 , according to an example embodiment of inventive concepts. As described above with reference to  FIGS. 5A and 5B , the standard cell library D 42  may define standard cells included in a same functional group in which the standard cells provide the same function but have different structures. 
     Referring to  FIG. 6 , the standard cell library D 42  may define standard cells which provide the same function but have different boundary structures. For example, first through third standard cells C 61  through C 63  may provide the same function as standard cells which include input pins A, B, C, and D and the output pin Y, as illustrated in a plan view shown in the upper portion of  FIG. 6 , but may have different boundary structures, as illustrated in side views shown in the lower portion of  FIG. 6 . 
     The first through third standard cells C 61  through C 63  may have eaves sections (┌), respectively, protruding in the +X direction in BEOL regions BR 61 , BR 62 , and BR 63 , respectively, and may have step sections (┘), respectively, protruding in the −X direction in FEOL regions FR 61 , FR 62 , and FR 63 , respectively, thereby having the same orientation, i.e., the +X orientation. Meanwhile, the first through third standard cells C 61  through C 63  may have different boundary structures in the FEOL regions FR 61 , FR 62 , and FR 63 . In more detail, the first standard cell C 61  may have a boundary structure (e.g., no diffusion break) for connecting the FEOL region FR 61  with an FEOL region of another standard cell adjacent in the +X direction, e.g., connecting active regions and fins with each other. The second standard cell C 62  may include a DDB region DR 62 , in which a DDB separates the FEOL region FR 62  from an FEOL region of another standard cell adjacent in the +X direction, at a side of the FEOL region FR 62 . The third standard cell C 63  may include an SDB region SR 63 , in which an SDB separates the FEOL region FR 63  from an FEOL region of another standard cell adjacent in the +X direction, at a side of the FEOL region FR 63 . Accordingly, when the standard cells are placed in operation S 421  shown in  FIG. 4 , appropriate standard cells may be selected from among standard cells in a same functional group defined in the standard cell library D 42 , based on the boundary structures of standard cells placed to be adjacent to each other. Although only three standard cells C 61  through C 63  having different boundary structures are shown in  FIG. 6 , additional standard cells may also be understood as being available according to combinations of different boundary structures (e.g., no diffusion break, DDB, and SDB) at opposite sides of an FEOL region. 
       FIG. 7  is a diagram of an example of a standard cell defined by a standard cell library, according to an example embodiment of inventive concepts. 
     The standard cell library may define an orientation of a standard cell in various ways. In some embodiments, the standard cell library may define the shape of a BEOL region and the shape of an FEOL region in a standard cell according to an orientation. For example, the standard cell library may differently define, on a plane, the boundary of a BEOL region and the boundary of an FEOL region in a standard cell by defining the shape of an eaves section and the shape of a step section. In some example embodiments, the standard cell library may define a standard cell having an orientation using a virtual layer. For example, as shown in  FIG. 7 , the standard cell library may define that the boundary of a BEOL region BR 71  of a first standard cell C 71  is the same as the boundary of an FEOL region FR 71  of the first standard cell C 71  on a plane, and may mark portions to be respectively removed from the BEOL region BR 71  and the FEOL region FR 71  with marking layers ML 71  and ML 72 , respectively. When standard cells are placed (e.g., in operation S 421  in  FIG. 4 ), the marking layers ML 71  and ML 72  may be recognized by a P&amp;R tool, so that the P&amp;R tool may recognize the orientation of the first standard cell C 71 . Examples of an operation of generating a layout of an integrated circuit, referring to a standard cell library defining standard cells, will be described with reference to the drawings below. 
       FIG. 8A  is a flowchart of a method of generating a layout of an integrated circuit including standard cells which have different orientations and are placed adjacent to each other, according to an example embodiment of inventive concepts.  FIG. 8B  is a diagram of an example of the layout generated using the method illustrated in  FIG. 8A . According to some embodiments of inventive concepts, standard cells having different orientations may be placed adjacent to each other, and the boundary structure of the standard cells may be changed. 
     Referring to  FIG. 8A , standard cells may be placed such that eaves sections of the respective standard cells are in contact, e.g. in direct contact, with each other in operation S 81 . For example, as shown in the left of  FIG. 8B , a first standard cell C 81  having the +X orientation and a second standard cell C 82  having the −X orientation may be placed adjacent to each other. The first and second standard cells C 81  and C 82  may respectively include SDB regions SR 81  and SR 82 , for forming an SDB, at a side of an FEOL region FR 81  and a side of an FEOL region FR 82 , respectively. A BEOL region BR 81  of the first standard cell C 81  may be in contact, e.g. in direct contact, with a BEOL region BR 82  of the second standard cell C 82 . Accordingly, a space is formed between the FEOL regions FR 81  and FR 82 . 
     Referring back to  FIG. 8A , SDB regions facing each other may be removed and a DDB may be placed in operation S 82 . For example, as shown in the right of  FIG. 8B , the SDB regions SR 81  and SR 82  may be removed from the sides of the FEOL regions FR 81  and FR 82  of the first and second standard cells C 81  and C 82 , and a DDB DB 80  may be placed between the FEOL regions FR 81  and FR 82 . Accordingly, the DDB DB 80 , which may be more advantageous than an SDB in terms of semiconductor processes, may be generated without influencing the performance of the first and second standard cells C 81  and C 82 . The removing of the SDB regions SR 81  and SR 82  and the placement of the DDB DB 80  may be performed after the placement (for example, during P&amp;R) of the first and second standard cells C 81  and C 82  and/or may be performed on the layout (for example, during design polishing) of the integrated circuit after routing is completed. For example, operation S 82  shown in  FIG. 8A  may be included in operation S 420  or S 430  shown in  FIG. 4 . 
       FIG. 9A  is a diagram of examples of standard cells including a power tap at one side thereof, the standard cells being defined in a standard cell library, according to an example embodiment of inventive concepts.  FIG. 9B  is a flowchart of a method of generating a layout of an integrated circuit including a structure in which standard cells merge with each other, the standard cells having different orientations and being placed adjacent to each other, according to an example embodiment of inventive concepts.  FIG. 9C  is a diagram of an example of the layout generated using the method illustrated in  FIG. 9B . According to some embodiments of inventive concepts, standard cells having different orientations may be placed adjacent to each other, and portions of the standard cells may merge with each other, so that spatial efficiency may be increased. The increased spatial efficiency may reduce chip size, which may increase the number of available integrated circuits produced on a given substrate. The increased spatial efficiency may increase a manufacturing yield of the integrated circuit. The increased spatial efficiency may reduce a unit cost of manufacturing the integrated circuit. 
     Referring to  FIG. 9A , the standard cell library may define standard cells having a power tap at one side thereof. For example, as shown in  FIG. 9A , first through fourth standard cells C 91  through C 94  may have the +X orientation and may respectively include pairs of power taps PT 91   a  and PT 91   b , PT 92   a  and PT 92   b , PT 93   a  and PT 93   b , and PT 94   a  and PT 94   b  adjacent to a step section. A power tap may refer to a pattern which provides a path for supplying a power supply voltage to a standard cell. For example, a power tap may include a contact structure connected to a source of a transistor included in a standard cell and may transmit a positive supply voltage or a negative supply voltage to the transistor. The first through fourth standard cells C 91  through C 94  may include contact structures and vias in proximity to a step section, the contact structures and the vias transmitting a positive supply voltage and a negative supply voltage to transistors. Although standard cells having the +X orientation are illustrated in  FIG. 9A , the standard cell library may define standard cells which have the −X orientation and include a power tap adjacent to a step section, for example, standard cells symmetrical with the first through fourth standard cells C 91  through C 94  with respect to an axis parallel with the Y-axis. Although each of the power taps PT 91   a , PT 91   b , PT 92   a , PT 92   b , PT 93   a , PT 93   b , PT 94   a , and PT 94   b  is placed in a standard cell to be adjacent to a step section of the standard cell in  FIG. 9A , the step section may include at least part of the power tap in other embodiments. As described below, when adjacent standard cells merge with each other, a power tap may be shared between the standard cells, and an area of the standard cells may be decreased. Accordingly, in some embodiments of inventive concepts, standard cells having an orientation may be designed to have a power tap at one side thereof. This will be described in detail with reference to  FIGS. 17A and 17B  below. 
     Referring to  FIG. 9B , standard cells may be placed such that power taps of the respective standard cells are adjacent to each other in operation S 91 . For example, as shown in the left of  FIG. 9C , a fifth standard cell C 95  and a sixth standard cell C 96  having different orientations may be placed adjacent to each other. The fifth standard cell C 95  may include power taps PT 95   a  and PT 95   b  adjacent to a step section thereof and the sixth standard cell C 96  may include power taps PT 96   a  and PT 96   b  adjacent to a step section thereof. While an FEOL region FR 95  of the fifth standard cell C 95  is in contact with an FEOL region FR 96  of the sixth standard cell C 96 , a space may be formed between a BEOL region BR 95  of the fifth standard cell C 95  and a BEOL region BR 96  of the sixth standard cell C 96 . 
     Referring back to  FIG. 9B , the standard cells may be merged with each other such that the standard cells share a power tap with each other in operation S 92 . For example, as shown in the right of  FIG. 9C , the fifth and sixth standard cells C 95  and C 96  are merged to share power taps PT 97   a  and PT 97   b , so that a seventh standard cell C 97  is generated. Accordingly, an X-axis direction length X 92  of the seventh standard cell C 97  may be less than an X-axis direction length X 91  occupied by the fifth and sixth standard cells C 95  and C 96  placed adjacent to each other. As a result, the spatial efficiency of an integrated circuit may be increased. The increased spatial efficiency may reduce chip size, which may increase the number of available integrated circuits produced on a given substrate. The increased spatial efficiency may increase a manufacturing yield of the integrated circuit. The increased spatial efficiency may reduce a unit cost of manufacturing the integrated circuit. Standard cell merging shown in  FIG. 9C  may be performed after the placement (for example, during P&amp;R) of the fifth and sixth standard cells C 95  and C 96  or may be performed on the layout (for example, during design polishing) of the integrated circuit after routing is completed. For example, operation S 92  shown in  FIG. 9B  may be included in operation S 420  or S 430  shown in  FIG. 4 . 
       FIG. 10A  is a flowchart of a method of generating a layout of an integrated circuit, in which standard cells having different pin placements are selectively placed, according to an example embodiment of inventive concepts.  FIG. 10B  is a diagram of examples of standard cells having different pin placements. As described below, standard cells suitable for routing may be selected from among standard cells having different pin placements and placed in an integrated circuit, according to some embodiments of inventive concepts. Operations S 101  and S 102  shown in  FIG. 10A  may be included in operation S 420  shown in  FIG. 4 . 
     Referring to  FIG. 10A , standard cells having the same function and orientation but different pin placements may be acquired in operation S 101 . For example, as shown in  FIG. 10B , while a first standard cell C 101  and a second standard cell C 102  may have the +X orientation as inverters including the input pin A and the output pin Y, the first and second standard cells C 101  and C 102  may have different placements of the input pin A and the output Y. When standard cells having the same orientation are consecutively placed, routing congestion may occur due to the positions of input and output pins of the standard cells. Accordingly, a standard cell library may define standard cells which have the same function and orientation but different pin placements, and standard cells having different pin placements may be acquired from the standard cell library. In some example embodiments, the standard cell library may define standard cells of which FEOL regions are symmetrical with respect to an axis parallel with the Y-axis for different pin placements. At this time, pin placements of the standard cells may be symmetrical with respect to an axis parallel with the Y-axis. 
     Referring back to  FIG. 10A , one standard cell may be selected from among the standard cells and placed, based on routing, in operation S 102 . For example, as shown in  FIG. 10B , while the first standard cell C 101  may be suitable when an output signal of a standard cell adjacent in the −X direction is applied to the input pin A, the second standard cell C 102  is suitable when a standard cell adjacent in the −X direction receives an output signal output through the output pin Y. As a result, routing congestion may be decreased, the amount of time taken to generate the layout of an integrated circuit may also be decreased, and performance of the integrated circuit may be increased due to a simple routing architecture. 
       FIG. 11A  is a flowchart of a method of generating a layout of an integrated circuit by modifying standard cells, according to an example embodiment of inventive concepts.  FIG. 11B  is a diagram of an example of the layout generated using the method illustrated in  FIG. 11A . As described below, the orientation of a standard cell may be changed during P&amp;R, according to some embodiments of inventive concepts. 
     Referring to  FIG. 11A , a standard cell having a particular orientation may be acquired in operation S 111 . In some example embodiments, a standard cell library may define a standard cell having the same function as a previously defined standard cell but a different orientation than the defined standard cell. For example, as shown in  FIG. 11B , the standard cell library may define a first standard cell C 111  having the −X direction as an A 0122  which includes input pins A 0 , A 1 , B 0 , and B 1  and the output pin Y. 
     Referring back to  FIG. 11A , the acquired standard cell is flipped and placed based on the boundary of a standard cell which the acquired standard cell will be placed adjacent to, in operation S 112 . For example, when an adjacent standard cell placed on the right or left of the first standard cell C 111  has the +X orientation in  FIG. 11B , a space may be generated, similarly to the embodiments described above with reference to  FIGS. 2C and 2D . In this case, when the first standard cell C 111  is flipped during P&amp;R (e.g., operation S 420  in  FIG. 4 ), a second standard cell C 112  symmetrical with the first standard cell C 111  with respect to an axis parallel with the Y-axis may be generated, and the second standard cell C 112  may be placed adjacent to the standard cell having the +X orientation. When a standard cell library defining only standard cells having one orientation, unlike the standard cell library D 42  shown in  FIG. 4 , is used, an operation of flipping and placing a standard cell according to the orientation of the standard cell may be performed during P&amp;R. 
       FIG. 12  is a flowchart of a method of generating a standard cell library including a standard cell having an orientation, according to an example embodiment of inventive concepts. As described above with reference to  FIG. 1 , since a DDB resolves some issues with semiconductor processes, standard cells supporting a DDB may be developed at the initial operational stage of semiconductor processes. As the issues with semiconductor processes become resolved thereafter, standard cells supporting an SDB may be developed. As described below, when standard cells supporting an SDB have an orientation, the standard cells supporting an SDB may be more easily generated from standard cells supporting a DDB. In some embodiments, the method illustrated in  FIG. 12  may be performed by a computing system (e.g.,  200  in  FIG. 20 ) including a processor and memory. 
     An input standard cell library D 121  may be acquired in operation S 121 . The input standard cell library D 121  may include information D 121 _ 1  about standard cells supporting a DDB. The input standard cell library D 121  may be non-transiently stored in a computer-readable storage medium and/or may be received through a communication channel. 
     A standard cell having an SDB and an orientation may be generated in operation S 122 . As described above with reference to  FIG. 1 , since a standard cell having an orientation may have the same patterns of a BEOL region as a standard cell supporting a DDB, the standard cell having an orientation may be more easily generated. Operation S 122  will be described in detail with reference to  FIGS. 13A through 17B  below. 
     An output standard cell library D 122  may be generated in operation S 123 . The output standard cell library D 122  may include information D 122 _ 1  about standard cells supporting an SDB. The output standard cell library D 122  may be used to generate a layout of an integrated circuit, as described above with reference to  FIG. 4 , and/or may be used to verify an integrated circuit, as described with reference to  FIG. 18  below. 
       FIG. 13A  is a flowchart of a method of generating a standard cell having an orientation, according to an example embodiment of inventive concepts.  FIG. 13B  is a diagram of an example of the standard cell generated using the method illustrated in  FIG. 13A . Operations S 131  and S 132  shown in  FIG. 13A  may be included in operation S 122  shown in  FIG. 12 . 
     Referring to  FIG. 13A , an FEOL region of a standard cell may be removed by ½ CPP from each of opposite sides thereof in operation S 131 . For example, as shown in  FIG. 13B , a first standard cell C 131  supporting a DDB may include, at opposite sides thereof, DDB regions DR 131   a  and DR 131   b  for the DDB. Since each of the DDB regions DR 131   a  and DR 131   b  may have a width (e.g., an X-axis direction length) of ½ CPP at a side of the first standard cell C 131 , the DDB regions DR 131   a  and DR 131   b  of the first standard cell C 131  may be removed when an FEOL region of the first standard cell C 131  is removed by ½ CPP from each of the opposite sides thereof. Accordingly, while the FEOL region of the first standard cell C 131  may have an X-axis direction length of 3 CPP, an FEOL region of a second standard cell C 132  may have an X-axis direction length of 2 CPP. 
     Referring back to  FIG. 13A , a BEOL region of the standard cell may be removed by a total of 1 CPP from opposite sides thereof in operation S 132 . For example, as shown in  FIG. 13B , after the DDB regions DR 131   a  and DR 131   b  are removed from the first standard cell C 131 , the output pin Y in a BEOL region of the first standard cell C 131  may protrude in the +X direction. When the BEOL region of the first standard cell C 131  is removed by a total of 1 CPP from opposite sides thereof without removing the output pin Y protruding the +X direction, the second standard cell C 132  having the +X orientation may be generated. Accordingly, the second standard cell C 132  may have an X-axis direction length of 2 CPP and may include the BEOL region shifted from the FEOL region in the +X direction. As shown in  FIG. 13B , SDB regions SR 132   a  and SR 132   b  extending in the Y-axis direction may be respectively added at the opposite sides of the FEOL region of the second standard cell C 132 . 
       FIG. 14  is a flowchart of a method of generating a standard cell having an orientation, according to an embodiment of inventive concepts. A standard cell having a different orientation may be generated from a standard cell having a particular orientation. 
     A standard cell having a particular orientation may be acquired in operation S 141 . For example, a standard cell (e.g., C 132  in  FIG. 13B ) having the +X orientation may be generated using the method illustrated in  FIG. 13B , and standard cells having the +X orientation may be acquired. 
     The acquired standard cell may be flipped in operation S 142 . For example, when the second standard cell C 132  having the +X orientation, as shown in  FIG. 13B , is acquired, a standard cell having the same function as the second standard cell C 132  but the −X orientation may be generated by flipping the second standard cell C 132  over an axis parallel with the Y-axis. 
       FIG. 15A  is a flowchart of a method of generating a standard cell having an orientation, according to still an example embodiment of inventive concepts.  FIG. 15B  is a diagram of an example of a standard cell generated using the method illustrated in  FIG. 15A . Operations S 151  and S 152  shown in  FIG. 15A  may be included in operation S 122  shown in  FIG. 12 . 
     Referring to  FIG. 15A , a standard cell from opposite sides of which a BEOL region is not removable may be acquired in operation S 151 . For example, as shown in  FIG. 15B , an FEOL region FR 151  of a first standard cell C 151  may be removed by ½ CPP from each of opposite sides thereof by removing DDB regions, but a BEOL region BR 151  of the first standard cell C 151  cannot be removed by a total of 1 CPP from opposite sides thereof due to the input pin A and the output pin Y. 
     Referring back to  FIG. 15A , the boundary of an FEOL region of the standard cell is shifted in operation S 152 . For example, as shown in  FIG. 15B , the boundary of the FEOL region FR 151  of the first standard cell C 151  may be shifted by ½ CPP in the −X direction, and therefore, a second standard cell C 152  may have an FEOL region FR 152  having the same X-axis direction length as the FEOL region FR 151  of the first standard cell C 151  and extending from a gate line in the X-axis direction. As a result, a BEOL region BR 152  of the second standard cell C 152  may include an eaves section (┌) protruding in the +X direction and the FEOL region FR 152  of the second standard cell C 152  may include a step section (┘) protruding in the −X direction. As well as the FEOL region FR 151  of the first standard cell C 151 , the BEOL region BR 151  may also be shifted. As shown in  FIG. 15B , the second standard cell C 152  may include the BEOL region BR 152  resulting from shifting the BEOL region BR 151  of the first standard cell C 151  in the −X direction. 
       FIG. 16A  is a flowchart of a method of generating a standard cell having an orientation, according to yet another embodiment of inventive concepts.  FIG. 16B  is a diagram of an example of a standard cell generated using the method illustrated in  FIG. 16A . Operations S 161  and S 162  shown in  FIG. 16A  may be included in operation S 122  shown in  FIG. 12 . 
     Referring to  FIG. 16A , a standard cell including a pattern removable from opposite sides of a BEOL region may be acquired in operation S 161 . For example, as shown in  FIG. 16B , a metal layer pattern M 161  of a first standard cell C 161  may include a portion P 161  extending from a via V 161  in the −X direction. The portion P 161  of the metal layer pattern M 161  is not electrically connected to other patterns than the via V 161  electrically connecting the metal layer pattern M 161  with a contact structure and may thus be removable. Similarly, a portion P 162  of the metal layer pattern M 161  may also be removable. 
     Referring back to  FIG. 16A , at least part of the pattern may be removed and the BEOL region may be reduced in operation S 162 . For example, as in a second standard cell C 162  shown in  FIG. 16B , the portion P 161  of the metal layer pattern M 161  of the first standard cell C 161  may be removed, and therefore, the second standard cell C 162  may include a BEOL region having a shorter X-axis direction length than that of the first standard cell C 161 . Accordingly, similarly to the embodiment described above with reference to  FIGS. 13A and 13B , an FEOL region of the second standard cell C 162  may be generated by removing DDB regions from the first standard cell C 161 , and consequently, the second standard cell C 162  may have the +X orientation. 
       FIG. 17A  is a flowchart of a method of generating a standard cell having an orientation, according to an example embodiment of inventive concepts.  FIG. 17B  is a diagram of an example of a standard cell generated using the method illustrated in  FIG. 17A . Operations S 171  and S 172  shown in  FIG. 17A  may be included in operation S 122  shown in  FIG. 12 . 
     Referring to  FIG. 17A , a power tap for transmitting a power supply voltage may be shifted or generated to be adjacent to a step section in operation S 171 . As described above with reference to  FIG. 15B , the second standard cell C 152  shown in  FIG. 15B  may be generated by shifting the boundary of the FEOL region FR 151  of the first standard cell C 151 . At this time, a power tap may be placed adjacent to a portion protruding due to the shift of the FEOL region FR 151 , e.g., the step section (┘) of the FEOL region FR 152 , or the power tap may be placed such that at least part of the power tap is included in the step section (┘). For example, as shown in  FIG. 17B , when power taps PT 171  and PT 172  are generated to be adjacent to the step section (┘) of the second standard cell C 152  shown in  FIG. 15B , a first standard cell C 171  shown in  FIG. 17B  may be generated. 
     Referring back to  FIG. 17A , a pattern may be modified not to change the function of a standard cell in operation S 172 . For example, the input pin A electrically connected to a gate line GL 171  may be influenced by the power taps PT 171  and PT 172  in the first standard cell C 171  shown in  FIG. 17B . For this reason, a gate cut CT 171  removing the gate line GL 171  may be generated, as in a second standard cell C 172 . Accordingly, as described above with reference to  FIGS. 9A through 9C , the second standard cell C 172  may have a structure allowing the second standard cell C 172  to share a power tap with an adjacent standard cell, thereby contributing to an increase in spatial efficiency of an integrated circuit. The increased spatial efficiency may reduce chip size, which may increase the number of available integrated circuits produced on a given substrate. The increased spatial efficiency may increase a manufacturing yield of the integrated circuit. The increased spatial efficiency may reduce a unit cost of manufacturing the integrated circuit. 
       FIG. 18  is a diagram of a method S 180  of verifying an integrated circuit including standard cells having an orientation, according to an example embodiment of inventive concepts. The method S 180  shown in  FIG. 18  may be performed by a computing system (e.g.,  200  in  FIG. 20 ) including a processor and memory. 
     The method S 180  may include a plurality of operations S 181  through S 183  and may generate result data D 184  from netlist data D 181  and layout data D 182 , referring to a standard cell library D 183 . As described above with reference to  FIG. 4 , the netlist data D 181  may include a netlist describing standard cells and connection relationships among the standard cells in an integrated circuit. The netlist is generated through logic synthesis or the like. The layout data D 182  may be generated by placing and routing standard cells based on the netlist data D 181 , referring to the standard cell library D 183 . The layout data D 182  may represent the layout of an integrated circuit. The standard cell library D 183  may include a first group D 183 _ 1  including standard cells having the +X orientation, a second group D 183 _ 2  including standard cells having the −X orientation, and a third group D 183 _ 3  including standard cells having the ±X orientation. Standard cells included in a same functional group may have different characteristics according to orientations. The first through third groups D 183 _ 1  through D 183 _ 3  may individually define information about characteristics of standard cells. 
     Design rule check (DRC) may be performed in operation S 181 . Design rules may be defined based on semiconductor processes, and may define, for example, a minimum width of a pattern and a minimum distance between patterns. Whether the integrated circuit layout defined by the layout data D 182  complies with the design rules may be verified, referring to the first through third groups D 183 _ 1  through D 183 _ 3  included in the standard cell library D 183 . When a portion not complying with the design rules is detected, the result data D 184  including coordinates of the portion, a violated design rule, an error, etc. may be generated. Further optimization may be performed and operation S 181  may be iterated, e.g. may be iterated to generate a DRC-clean design, i.e. a design that does not have a portion that does not comply with the design rules. 
     Layout versus schematic (LVS) may be performed in operation S 182 . The LVS may refer to an operation of verifying whether an integrated circuit defined by the netlist data D 181  agrees with an integrated circuit defined by the layout data D 182 . For example, whether standard cells and nodes included in the netlist data D 181  exist in the layout defined by the layout data D 182  may be verified. The LVS may be performed, referring to the first through third groups D 183 _ 1  through D 183 _ 3  included in the standard cell library D 183 , and the result data D 184  including information about a portion not agreeing between the netlist data D 181  and the layout data D 182  may be generated. Further optimization may be performed and operation S 182  may be iterated, e.g. may be iterated to generate an LV-clean design, i.e. a design that does not have a portion that does not agree between the netlist data D 181  and the layout data D 182 . 
     Parasitic extraction (PEX) may be performed in operation S 183 . The PEX may refer to an operation of extracting parasitic components from the layout of an integrated circuit defined by the layout data D 182  in order to simulate the performance, e.g., operating speed or power consumption, of the integrated circuit. For example, resistance and capacitance of an interconnection forming a node may be extracted from the layout data D 182 , and an equivalent circuit of the interconnection including the extracted resistance and capacitance may be generated. Parasitic components may be extracted from the layout data D 182 , referring to the first through third groups D 183 _ 1  through D 183 _ 3  included in the standard cell library D 183 , and the result data D 184  including information about the extracted parasitic components may be generated. 
       FIG. 19  is a block diagram of a system-on-chip (SoC)  190  according to some embodiments of inventive concepts. The SoC  190  may be a semiconductor device and may include an integrated circuit according to an example embodiment of inventive concepts. The SoC  190  is implemented by integrating complex functional blocks, such as intellectual properties (IPs) performing various functions, into a single chip. According to an example embodiment of inventive concepts, a standard cell may be included in each of the functional blocks of the SoC  190 , and therefore, the SoC  190  may have increased spatial efficiency and verified performance. The increased spatial efficiency may reduce chip size, which may increase the number of available integrated circuits produced on a given substrate. The increased spatial efficiency may increase a manufacturing yield of the integrated circuit. The increased spatial efficiency may reduce a unit cost of manufacturing the integrated circuit. 
     Referring to  FIG. 19 , the SoC  190  may include a modem  192 , a display controller  193 , memory  194 , an external memory controller  195 , a central processing unit (CPU)  196 , a transaction unit  197 , a power management integrated circuit (PMIC)  198 , and a graphics processing unit (GPU)  199 . The functional blocks of the SoC  190  may communicate with one another through a system bus  191 . 
     The CPU  196 , which may control all operations of the SoC  190 , may control operations of other functional blocks including the modem  192 , the display controller  193 , the memory  194 , the external memory controller  195 , the CPU  196 , the transaction unit  197 , the PMIC  198 , and the GPU  199 . The modem  192  may demodulate a signal received from outside the SoC  190  or may modulate a signal generated in the SoC  190  and transmit the signal to outside of the SoC  190 . The external memory controller  195  may control operations of transmitting and receiving data to and from an external memory device connected to the SoC  190 . For example, programs and/or data stored in the external memory device may be provided to the CPU  196  or the GPU  199  under the control of the external memory controller  195 . The GPU  199  may execute program instructions involved in graphics processing. The GPU  199  may receive graphic data through the external memory controller  195  and may transmit processed graphic data to outside of the SoC  190  through the external memory controller  195 . The transaction unit  197  may monitor a data transaction of each functional block. The PMIC  198  may control power supplied to each functional block according to the control of the transaction unit  197 . The display controller  193  may control a display (or a display device) outside the SoC  190  and transmit data generated in the SoC  190  to the display. 
     The memory  194  may be or may include non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM), flash memory, phase-change random access memory (PRAM or PCRAM), resistance RAM (RRAM), nano floating gate memory (NFGM), polymer RAM (PoRAM), magnetic RAM (MRAM), or ferroelectric RAM (FRAM or FeRAM), and/or may be or may include volatile memory, such as dynamic RAM (DRAM), static RAM (SRAM), mobile DRAM, double data rate (DDR) synchronous DRAM (SDRAM), low power DDR (LPDDR) SDRAM, graphics DDR (GDDR) SDRAM, or Rambus DRAM (RDRAM). 
       FIG. 20  is a block diagram of a computing system  200  including memory storing a program, according to an example embodiment of inventive concepts. At least some operations among operations included in a method of fabricating an integrated circuit (e.g., the method shown in  FIG. 4 ), operations included in a method of generating a layout of an integrated circuit (e.g., S 420  in  FIG. 4 ), and/or operations included in a method of generating a standard cell library (e.g., the method shown in  FIG. 12 ), according to embodiments of inventive concepts, may be performed in the computing system  200 . 
     The computing system  200  may be a stationary computing system such as a desktop computer, a workstation, or a server or may be a portable computing system such as a laptop computer. As shown in  FIG. 20 , the computing system  200  may include a processor  210 , input/output (I/O) devices  220 , a network interface  230 , RAM  240 , ROM  250 , and a storage  260 . The processor  210 , the I/O devices  220 , the network interface  230 , the RAM  240 , the ROM  250 , and the storage  260  may be connected to a bus  270  and may communicate with one another through the bus  270 . 
     The processor  210  may be referred to as a processing unit and may include at least one core, which may execute an instruction set (e.g., Intel Architecture-32 (IA-32), 64-bit extension IA-32, x86-64, PowerPC, Sparc, microprocessor without interlocked pipeline stage (MIPS), advanced recued instruction set computer (RISC) machine (ARM), or IA-64), like a microprocessor, an application processor (AP), a digital signal processor (DSP), or a GPU. For example, the processor  210  may access memory, i.e., the RAM  240  or the ROM  250 , through the bus  270  and may execute instructions stored in the RAM  240  or the ROM  250 . 
     The RAM  240  may store a program  241  for fabricating an integrated circuit, according to an example embodiment of inventive concepts, or may store at least part of the program  241 . The program  241  may enable the processor  210  to perform at least some operations among operations included in a method of fabricating an integrated circuit, operations included in a method of generating a layout of an integrated circuit, and/or operations included in a method of generating a standard cell library (e.g., the method shown in  FIG. 12 ). In other words, the program  241  may include a plurality of instructions which can be executed by the processor  210 . The instructions included in the program  241  may enable the processor  210  to perform, for example, at least some operations included in the above-described flowcharts. 
     The storage  260  may not lose data stored therein even when power supplied to the computing system  200  is cut off. The storage  260  may include a non-volatile memory device or a storage medium such as a magnetic tape, an optical disc, or a magnetic disc. The storage  260  may be removable from the computing system  200 . The storage  260  may store the program  241  according to an example embodiment of inventive concepts. Before being executed by the processor  210 , the program  241  or at least part of the program  241  may be loaded from the storage  260  to the RAM  240 . Alternatively or additionally, the storage  260  may store a file written in program language, and the program  241  generated by a compiler from the file or at least part of the program  241  may be loaded to the RAM  240 . The storage  260  may also store a database (DB)  261 . The DB  261  may include at least part of information, e.g., the standard cell library D 42  shown in  FIG. 4 , the input standard cell library D 121  shown in  FIG. 12 , and the output standard cell library D 122  shown in  FIG. 12 , required or used to design an integrated circuit. 
     The storage  260  may also store data to be processed by the processor  210  or data that has been processed by the processor  210 . In other words, the processor  210  may generate data by processing data stored in the storage  260  or may store generated data in the storage  260  according to the program  241 . For example, the storage  260  may store the RTL data D 41 , the net list data D 43  and/or the layout data D 44  show in  FIG. 4  or the net list data D 181 , the layout data D 182  and/or the result data D 184  show in  FIG. 18 . 
     The I/O devices  220  may include an input device such as a keyboard or a pointing device and an output device such as a display device or a printer. For example, a user may trigger the execution of the program  241  by the processor  210 , input the RTL data D 41  and/or the net list data D 43  shown in  FIG. 4 , and check the layout data D 44  shown in  FIG. 4 , through the I/O devices  220 . 
     The network interface  230  may provide an access to a network outside the computing system  200 . For example, the network may include a plurality of computing systems and communication links. The communication links may include wired links, optical links, wireless links, or other types of links. 
     The various operations of methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software component(s), circuits, and/or module(s). 
     The software may comprise an ordered listing of executable instructions_for implementing logical functions, and can be embodied in any “processor-readable medium” for use by or in connection with an instruction execution system, apparatus, or device, such as a single or multiple-core processor or processor-containing system. 
     The blocks or steps of a method or algorithm and functions described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a tangible, non-transitory computer-readable medium. A software module may reside in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD ROM, or any other form of storage medium known in the art. 
     While inventive concepts have been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.