Patent Publication Number: US-2017365548-A1

Title: Optimizing Layout of Irregular Structures in Regular Layout Context

Description:
CLAIM OF PRIORITY 
     This application is a continuation application under 35 U.S.C. 120 of prior U.S. application Ser. No. 13/898,155, filed May 20, 2013, issued as U.S. Pat. No. 9,754,878, on Sep. 5, 2017, which is a continuation application under 35 U.S.C. 120 of prior U.S. application Ser. No. 12/481,445, filed Jun. 9, 2009, issued as U.S. Pat. No. 8,448,102, on May 21, 2013, which: 
     1) claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/060,090, filed Jun. 9, 2008, and 
     2) is a continuation-in-part application under 35 U.S.C. 120 of U.S. application Ser. No. 12/013,342, filed Jan. 11, 2008, issued as U.S. Pat. No. 7,917,879, on Mar. 29, 2011, which claims priority under 35 U.S.C. 119(e) to both U.S. Provisional Patent Application No. 60/963,364, filed Aug. 2, 2007, and U.S. Provisional Patent Application No. 60/972,394, filed Sep. 14, 2007, and 
     3) is a continuation-in-part application under 35 U.S.C. 120 of prior U.S. application Ser. No. 12/212,562, filed Sep. 17, 2008, issued as U.S. Pat. No. 7,842,975, on Nov. 30, 2010, which is a continuation application under 35 U.S.C. 120 of U.S. application Ser. No. 11/683,402, filed Mar. 7, 2007, issued as U.S. Pat. No. 7,446,352, on Nov. 4, 2008, which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 60/781,288, filed Mar. 9, 2006. 
     The disclosure of each above-identified patent application is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     A push for higher performance and smaller die size drives the semiconductor industry to reduce circuit chip area by approximately 50% every two years. The chip area reduction provides an economic benefit for migrating to newer technologies. The 50% chip area reduction is achieved by reducing the feature sizes between 25% and 30%. The reduction in feature size is enabled by improvements in manufacturing equipment and materials. For example, improvement in the lithographic process has enabled smaller feature sizes to be achieved, while improvement in chemical mechanical polishing (CMP) has in-part enabled a higher number of interconnect layers. 
     In the evolution of lithography, as the minimum feature size approached the wavelength of the light source used to expose the feature shapes, unintended interactions occurred between neighboring features. Today minimum feature sizes are being reduced below 45 nm (nanometers), while the wavelength of the light source used in the photolithography process remains at 193 nm. The difference between the minimum feature size and the wavelength of light used in the photolithography process is defined as the lithographic gap. As the lithographic gap grows, the resolution capability of the lithographic process decreases. 
     An interference pattern occurs as each shape on the mask interacts with the light. The interference patterns from neighboring shapes can create constructive or destructive interference. In the case of constructive interference, unwanted shapes may be inadvertently created. In the case of destructive interference, desired shapes may be inadvertently removed. In either case, a particular shape is printed in a different manner than intended, possibly causing a device failure. Correction methodologies, such as optical proximity correction (OPC), attempt to predict the impact from neighboring shapes and modify the mask such that the printed shape is fabricated as desired. However, the quality of the light interaction prediction is declining as process geometries shrink and as the light interactions become more complex. 
     In view of the foregoing, solutions are sought for improvements in circuit design and layout that can improve management of lithographic gap issues as technology continues to progress toward smaller semiconductor device features sizes. 
     SUMMARY 
     In one embodiment, a method is disclosed for placing irregular layout shapes in a dynamic array architecture. The method includes bracketing an irregular wire layout region within a portion of a chip level layout. The bracketing is done by placing a first regular wire layout shape on a first side of the irregular wire layout region, and by placing a second regular wire layout shape on a second side of the irregular wire layout region. The method also includes placing one or more irregular wire layout shapes within the irregular wire layout region. A first edge spacing is maintained between the first regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the first regular wire layout shape. A second edge spacing is maintained between the second regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the second regular wire layout shape. The first and second edge spacings are defined to optimize lithography of the first and second regular wire layout shapes and of the irregular wire layout shapes within the irregular wire layout region. 
     In one embodiment, a computer readable storage medium is disclosed to include a semiconductor chip layout recorded in a digital format. The semiconductor chip layout includes irregular layout shapes placed in a dynamic array architecture. Also in the semiconductor chip layout, an irregular wire layout region within a portion of a chip level layout is bracketed by a first regular wire layout shape on a first side of the irregular wire layout region and by a second regular wire layout shape on a second side of the irregular wire layout region. The semiconductor chip layout further includes one or more irregular wire layout shapes placed within the irregular wire layout region. A first edge spacing is maintained between the first regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the first regular wire layout shape. A second edge spacing is maintained between the second regular wire layout shape and an outer irregular wire layout shape within the irregular wire layout region nearest to the second regular wire layout shape. The first and second edge spacings are defined to optimize lithography of the first and second regular wire layout shapes and of the irregular wire layout shapes within the irregular wire layout region. 
     In one embodiment, a method is disclosed for defining a virtual grate for a layout of a portion of a semiconductor chip level. The method includes an operation for identifying a preferred routing direction for a portion of a given chip level. The method also includes an operation for identifying each contact level related to the portion of the given chip level. Each identified contact level is defined by a respective related virtual grate defined by a respective set of parallel virtual lines extending in the preferred routing direction. Layout shapes within a given contact level are placed in accordance with the respective related virtual grate of the given contact level. The method further includes an operation for defining a trial virtual grate for the portion of the given chip level as a set of parallel virtual lines extending in the preferred routing direction. The set of parallel virtual lines of the trial virtual grate is defined to enable required connections between layout shapes placed in accordance with the trial virtual grate within the portion of the given chip level and layout shapes within each identified contact level. The method continues with an operation for determining whether a perpendicular spacing between adjacent virtual lines of the trial virtual grate provides for adequate lithographic reinforcement of layout shapes to be placed in accordance with the trial virtual grate. If the perpendicular spacing between adjacent virtual lines of the trial virtual grate is determined adequate, the method proceeds with recording the trial virtual grate as a final virtual grate of the portion of the given chip level. However, if the perpendicular spacing between adjacent virtual lines of the trial virtual grate is determined inadequate, the method proceeds by adjusting at least one related virtual grate of any identified contact level and by repeating the method operations beginning with the operation for defining a trial virtual grate for the portion of the given chip level. 
     Other aspects and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an exemplary CMOS transistor configuration, in accordance with one embodiment of the present invention; 
         FIG. 2A  shows a flowchart of a method for defining a virtual grate for a given chip level, or portion thereof, in accordance with one embodiment of the present invention; 
         FIG. 2B  shows virtual lines of a contact level virtual grate which indicate preferred placement locations in one dimension for contact level shapes, in accordance with one embodiment of the present invention; 
         FIG. 3A  shows a flowchart of a method for placement of shapes such that the impact of using irregular wires in conjunction with the dynamic array architecture may be minimized, and re-alignment to a virtual grate occurs for regular shapes outside of a layout region where there are irregular wires, in accordance with one embodiment of the present invention; 
         FIG. 3B  shows an exemplary layout defined in accordance with the method of  FIG. 3A  in which one irregular wire is placed such that a standard long edge-to-long edge spacing is used between one long edge of the irregular wire and a facing edge thereto of an adjacent and parallel regular wire, in accordance with one embodiment of the present invention; 
         FIG. 3C  shows an exemplary layout defined in accordance with the method of  FIG. 3A  in which multiple irregular wires are placed such that a standard long edge-to-long edge spacing is used between one long edge of each of the irregular wires and a facing edge thereto of an adjacent and parallel regular wire, in accordance with one embodiment of the present invention; 
         FIG. 3D  shows an exemplary layout defined in accordance with the method of  FIG. 3A  in which optimal spacing between facing long edges of adjacent regular and irregular wires and between facing long edges of adjacent irregular wires within an irregular wire layout region is based on minimization of differences between these long edge-to-long edge spacings within the irregular wire layout region, in accordance with one embodiment of the present invention; 
         FIG. 3E  shows an exemplary layout that demonstrates how spacing variation can be reduced by increasing the number of irregular wires within an irregular wire layout region, in accordance with one embodiment of the present invention; 
         FIG. 3F  shows a variant of the exemplary layout of  FIG. 3B , defined in accordance with the method of  FIG. 3A , in which one irregular wire is placed in conjunction with a sub-res wire within the irregular wire layout region, in accordance with one embodiment of the present invention; 
         FIG. 3G  is an illustration showing a variant of the exemplary layout of  FIG. 3C , defined in accordance with the method of  FIG. 3A , in which two irregular wires are placed in conjunction with a sub-res wire within the irregular wire layout region, in accordance with one embodiment of the present invention; 
         FIG. 4  shows an exemplary layout for a diffusion level, defined in accordance with the method of  FIG. 3A , in accordance with one embodiment of the present invention; 
         FIG. 5A  shows an exemplary layout in which irregular wires have non-standard widths, which may or may not be equal to each other and which are smaller than a standard width for regular wires, in accordance with one embodiment of the present invention; 
         FIG. 5B  shows an exemplary layout similar to that of  FIG. 5A  except that irregular wires, having widths that are less than standard width, are placed such that long edge-to-long edge spaces associated with irregular wires are defined to be similar to each other, but not necessarily equal to the standard spacing, in accordance with one embodiment of the present invention; 
         FIG. 5C  shows an exemplary layout with irregular wires having widths that are less than a standard width, in accordance with one embodiment of the present invention; 
         FIG. 6  shows an exemplary layout implementing a method to reduce negative electrical or manufacturing influences between layout shapes or layout regions by interposing other layout shapes between them, in accordance with one embodiment of the present invention; 
         FIG. 7  shows a variation of the exemplary layout of  FIG. 6  in which protective sub-res shapes are placed in lieu of protective regular wires, in accordance with one embodiment of the present invention; 
         FIG. 8A  shows an exemplary layout within which end gaps are varied to improve manufacturability, in accordance with one embodiment of the present invention; 
         FIG. 8B  shows an exemplary layout in which long regular wires are used to bound an irregular wire layout region, thereby serving as protective layout shapes between the irregular wire layout region and a surrounding layout area, in accordance with one embodiment of the present invention; 
         FIG. 8C  shows a variation of the exemplary layout of  FIG. 8B , in which sub-res shapes are used in lieu of long regular wires, in accordance with one embodiment of the present invention; 
         FIG. 8D  shows a layout region immediately adjacent to a long edge of a linear layout shape, in accordance with one embodiment of the present invention; 
         FIG. 8E  shows an exemplary layout in which regular wires of standard width are defined within a layout region, in accordance with one embodiment of the present invention; 
         FIG. 8F  shows an exemplary layout that includes a symmetrical arrangement of irregular wires, in accordance with one embodiment of the present invention; 
         FIG. 8G  shows a variation of the exemplary layout of  FIG. 8F  in which a layout shape is inserted between symmetrically arranged irregular wires, in accordance with one embodiment of the present invention; 
         FIG. 8H  shows an exemplary layout in which irregular wires are arranged in an array defined by four layout shape columns and one layout shape row, in accordance with one embodiment of the present invention; 
         FIG. 9A  shows an exemplary layout illustrating a method to reduce spacing variation by modifying one or more irregular wire widths such that long edge-to-long edge spacing after placement is satisfactory, in accordance with one embodiment of the present invention; 
         FIG. 9B  shows an exemplary layout in which two irregular wires are successively placed between regular wires, in accordance with one embodiment of the present invention; 
         FIG. 9C  shows an exemplary layout in which irregular shapes are placed between regular wires, in accordance with one embodiment of the present invention; 
         FIG. 10A  shows an exemplary layout in which an irregular wire is placed such that its centerline is coincident with a virtual grate line, in accordance with one embodiment of the present invention; 
         FIG. 10B  shows a variation of the exemplary layout of  FIG. 10A  in which the irregular wire is moved up to a virtual grate line, and a regular wire is moved up to another virtual grate line, in accordance with one embodiment of the present invention; and 
         FIG. 10C  shows a variation of the exemplary layout of  FIG. 10A  in which layout shapes are inserted in long edge spaces on each side of the irregular wire, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention. 
     Dynamic Array Architecture 
     The dynamic array architecture represents a semiconductor device design paradigm in which linear-shaped layout features are defined along a regular-spaced virtual grate (or regular-spaced virtual grid) in a number of levels of a cell, i.e., in a number of levels of a semiconductor chip. The virtual grate is defined by a set of equally spaced, parallel virtual lines extending across a given level in a given chip area. The virtual grid is defined by a first set of equally spaced, parallel virtual lines extending across a given level in a given chip area in a first direction, and by a second set of equally spaced, parallel virtual lines extending across the given level in the given chip area in a second direction, where the second direction is perpendicular to the first direction. In one embodiment, the virtual grate of a given level is oriented to be substantially perpendicular to the virtual grate of an adjacent level. However, in other embodiments, the virtual grate of a given level is oriented to be either perpendicular or parallel to the virtual grate of an adjacent level. 
     In one embodiment, each linear-shaped layout feature of a given level is substantially centered upon one of the virtual lines of the virtual grate associated with the given level. A linear-shaped layout feature is considered to be substantially centered upon a particular line of a virtual grate when a deviation in alignment between of the centerline of the linear-shaped layout feature and the particular line of the virtual grate is sufficiently small so as to not reduce a manufacturing process window from what would be achievable with a true alignment between of the centerline of the linear-shaped layout feature and the line of the virtual grate. 
     In one embodiment, the above-mentioned manufacturing process window is defined by a lithographic domain of focus and exposure that yields an acceptable fidelity of the layout feature. In one embodiment, the fidelity of a layout feature is defined by a characteristic dimension of the layout feature. Also, it should be understood that the centerline of a given linear-shaped layout feature is defined as a virtual line that passes through the cross-sectional centroid of the linear-shaped layout feature at all points along its length, wherein the cross-sectional centroid of the linear-shaped layout feature at any given point along its length is the centroid of its vertical cross-section area at the given point. 
     In another embodiment, some linear-shaped layout features in a given level may not be centered upon a virtual line of the virtual grate associated with the given level. However, in this embodiment, the linear-shaped layout features remain parallel to the virtual lines of the virtual grate, and hence parallel to the other linear-shaped layout features in the given level. Therefore, it should be understood that the various linear-shaped layout features defined in a layout of a given level are oriented to extend across the given level in a parallel manner. 
     Also, in the dynamic array architecture, in one embodiment, each linear-shaped layout feature is defined to be devoid of a substantial change in direction along its length. The lack of substantial change in direction of a linear-shaped layout feature is considered relative to the line of the virtual grate along which the linear-shaped layout feature is defined. In one embodiment, a substantial change in direction of a linear-shaped layout feature exists when the width of the linear-shaped layout feature at any point thereon changes by more than 50% of the nominal width of the linear-shaped layout feature along its entire length. In another embodiment, a substantial change in direction of a linear-shaped layout feature exists when the width of the linear-shaped layout feature changes from any first location on the linear-shaped layout feature to any second location on the linear-shaped layout feature by more that 50% of the linear-shaped layout feature width at the first location. Therefore, it should be appreciated that the dynamic array architecture specifically avoids the use of non-linear-shaped layout features, wherein a non-linear-shaped layout feature includes one or more bends within a plane of the associated level. 
     In the dynamic array architecture, variations in a vertical cross-section shape of an as-fabricated linear-shaped layout feature can be tolerated to an extent, so long as the variation in the vertical cross-section shape is predictable from a manufacturing perspective and does not adversely impact the manufacture of the given linear-shaped layout feature or its neighboring layout features. In this regard, the vertical cross-section shape corresponds to a cut of the as-fabricated linear-shaped layout feature in a plane perpendicular to the centerline of the linear-shaped layout feature. It should be appreciated that variation in the vertical cross-section of an as-fabricated linear-shaped layout feature along its length can correspond to a variation in width along its length. Therefore, the dynamic array architecture also accommodates variation in the width of an as-fabricated linear-shaped layout feature along its length, so long as the width variation is predictable from a manufacturing perspective and does not adversely impact the manufacture of the linear-shaped layout feature or its neighboring layout features. 
     Additionally, different linear-shaped layout features within a given level can be designed to have the same width or different widths. Also, the widths of a number of linear-shaped layout features defined along adjacent lines of a given virtual grate can be designed such that the number of linear-shaped layout features contact each other so as to form a single linear-shaped layout feature having a width equal to the sum of the widths of the number of linear-shaped layout features. 
     Within a given level defined according to the dynamic array architecture, proximate ends of adjacent, co-aligned linear-shaped layout features may be separated from each other by a substantially uniform gap. More specifically, adjacent ends of linear-shaped layout features defined along a common line of a virtual grate are separated by an end gap, and such end gaps within the level associated with the virtual grate may be defined to span a substantially uniform distance. Additionally, in one embodiment, a size of the end gaps is minimized within a manufacturing process capability so as to optimize filling of a given level with linear-shaped layout features. 
     Also, in the dynamic array architecture, a level can be defined to have any number of virtual grate lines occupied by any number of linear-shaped layout features. In one example, a given level can be defined such that all lines of its virtual grate are occupied by at least one linear-shaped layout feature. In another example, a given level can be defined such that some lines of its virtual grate are occupied by at least one linear-shaped layout feature, and other lines of its virtual grate are vacant, i.e., not occupied by any linear-shaped layout features. Furthermore, in a given level, any number of successively adjacent virtual grate lines can be left vacant. Also, the occupancy versus vacancy of virtual grate lines by linear-shaped layout features in a given level may be defined according to a pattern or repeating pattern across the given level. 
     Additionally, within the dynamic array architecture, vias and contacts are defined to interconnect a number of the linear-shaped layout features in various levels so as to form a number of functional electronic devices, e.g., transistors, and electronic circuits. Layout features for the vias and contacts can be aligned to a virtual grid, wherein a specification of this virtual grid is a function of the specifications of the virtual grates associated with the various levels to which the vias and contacts will connect. Thus, a number of the linear-shaped layout features in various levels form functional components of an electronic circuit. Additionally, some of the linear-shaped layout features within various levels may be non-functional with respect to an electronic circuit, but are manufactured nonetheless so as to reinforce manufacturing of neighboring linear-shaped layout features. It should be understood that the dynamic array architecture is defined to enable accurate prediction of semiconductor device manufacturability with a high probability. 
     In view of the foregoing, it should be understood that the dynamic array architecture is defined by placement of linear-shaped layout features on a regular-spaced grate (or regular-spaced grid) in a number of levels of a cell, such that linear-shaped layout features in a given level of the cell are oriented to be substantially parallel with each other in their traversal direction across the cell. Also, in one embodiment of the dynamic array architecture, prior to process compensation technique (PCT) processing, each linear-shaped layout feature is defined to be devoid of a substantial change in direction relative to its traversal direction. 
     Nomenclature 
     In the figures and text herein, certain naming conventions are applied as follows:
         VG: virtual grate;   VG lines: virtual lines of a virtual grate;   Wire: a linear shaped layout feature on a given level with a centerline parallel to a VG line of the given level and region thereof under consideration;   Conductive layout feature: a layout shape on a level such as active, gate electrode, local interconnect, metal (interconnect) level, or other level that may be conductive and is not a contact or via level;   Long edge: a linear shaped layout feature&#39;s edge that is oriented parallel to VG lines of the level in which the linear shaped layout feature is defined, regardless of the aspect ratio of the linear shaped layout feature;   Line end: a linear shaped layout feature edge that is oriented orthogonal (perpendicular) to VG lines for the level in which the linear shaped layout feature is defined;   End gap: a space between line ends of linear shaped layout features placed line end-to-line end;   Parallel wires: wires having parallel long edges and offset centerlines;   Width: a wire dimension orthogonal to the VG line upon which the wire is placed;   Regular wires: a number of wires of common width placed according to a VG of a given level;   Standard gap (standard spacing): a distance measured perpendicularly between facing long edges of adjacent and parallel regular wires;   Irregular wire: a wire in a given level that does not have the common width of other regular wires in the given level or that is not centered on a VG line of the given level;   Irregular spacing: a distance measured perpendicularly between long edges of wires that is not equal to the standard gap (standard spacing);   Spacing variation: a difference between irregular spacing and standard gap (standard spacing). In one embodiment, spacing variation may be defined as a maximum spacing variation within an area of a given level. In another embodiment, spacing variation may be defined as an average value within an area of a given level. In another embodiment, spacing variation may be defined based on a single instance of irregular spacing;   Sub-resolution (sub-res) shape: a shape that is drawn but intentionally not manufactured due to having one or more dimensions below the resolution capability of a manufacturing system. For example, at least one dimension (length or width, etc.) of the sub-res shape may be small enough to guarantee that the sub-res shape will not be resolved as a manufactured feature, even when the sub-res shape is placed in compliance with normal edge spacing constraints relative to other layout shapes;   Gate: a gate electrode feature defined as part of a transistor;   Irregular wire layout region: a layout region bounded by regular wires within which one or more irregular wires are placed.       

     Exemplary Embodiments 
     In one embodiment, a layout defined in accordance with the dynamic array architecture may include the following attributes: 1) shapes are rectangular, i.e., linear-shaped, 2) wire and contact pitch is substantially constant in a direction orthogonal to routing, 3) wire width is substantially constant, 4) side-to-side and end-of-line wire spacings are substantially constant, 5) overall shape density is as uniform as possible, and 6) the proximity of gaps in wires to other wire shapes is managed to avoid lithographic disturbance. It should be understood, however, that in some embodiments, a layout defined in accordance with the dynamic array architecture may not include all of the attributes associated with the above-mentioned embodiment. Methods and techniques are disclosed herein for enhancing layout in situations where particular layout areas or layout shapes do not strictly follow the dynamic array architecture but are contained within a layout that substantially follows the dynamic array architecture. 
     An exemplary CMOS transistor configuration is shown in  FIG. 1 . Gate electrode (gate) wires  160 - 162  each have a different width W 2  in comparison to a standard width W 1  of gate wires  110 - 118 . Gate wires  110 - 117  and  160 - 162  form gate electrodes of transistors where they overlap with active shapes  120 - 122 . Gate level wire  118  is an example of a wire on a gate electrode level that does not traverse an active level and is not used to form a gate electrode. Source or drain contact shapes such as  140 - 142  and gate contacts such as  143  and  144  are indicated as examples of shapes on the contact (CON) level. 
     Each gate electrode is defined to extend beyond the edges of its underlying active region. Each portion of a gate electrode that extends beyond an edge of its underlying active region is referred to as an overlap portion of the gate electrode. A traversal direction of a gate electrode relative to its underlying active region is defined as a direction that extends between the overlap portions of the gate electrode and that is perpendicular to the edges of the underlying active region beyond which the overlap portions of the gate electrode extend. For example, considering gate electrode feature  114 , overlapping portions  114 A and  114 B extend beyond active region edges  121 A and  121 B, respectively. Therefore, arrow  170  represents the traversal direction of gate electrode  114 , as arrow  170  extends between the overlap portions  114 A and  114 B of the gate electrode  114  and is perpendicular to the edges  121 A and  121 B of the underlying active region  121  beyond which the overlap portions  114 A and  114 B of the gate electrode  114  extend. 
     Gate dimensions which run perpendicular to the traversal direction of the gate over its underlying active region, such as W 1  and W 2 , are referred to as gate channel lengths. Use of multiple gate channel lengths in a given level represents one of many cases in which multiple values for a given type of dimension, e.g., width, can be applied to different layout shapes on a given level. This invention applies to any level in which non-standard shape dimensions may occur, wherein a given shape dimension is considered non-standard in a given level when a value of the given shape dimension varies among layout features in the given level. For ease of discussion, the principles of the present invention are described herein with respect to a gate level in various exemplary embodiments. However, it should be understood that the principles of the present invention as referenced to a gate level in the exemplary embodiments herein can be equally applied to any chip level. For example, the principles of the present invention can be equally applied to an active level, a local interconnect level, a metal (interconnect) level, a contact level, a via level, or essentially any other chip level. 
     Also shown in  FIG. 1  are lines  100 - 103  of a virtual grate (VG) for the gate level. The virtual lines  100 - 103  are spaced apart from each other by a constant line-to-line pitch P 1 .  FIG. 2A  is an illustration showing a flowchart of one method for defining a VG for a given chip level, or portion thereof, referred to as the given level hereafter. The method includes an operation  201  for identifying a preferred routing direction for the given level. The method also includes an operation  203  for identifying each related contact level, wherein a related contact level includes at least one shape that is to make contact with a shape in the given level. Virtual lines of a contact level VG indicate preferred placement locations in one dimension for contact level shapes, even if contact level shapes are not present on every virtual line of the contact level VG in a layout under consideration. An example of this may be seen in  FIG. 2B , where a VG for gate CON shapes includes virtual lines  181 ,  183 ,  185 , and  187 . The example of  FIG. 2B  shows gate CON shapes  142  and  143  present on VG lines  183  and  187 , and no gate CON shapes present on the other VG lines  181  and  185  for the gate CON level. 
     The method described in  FIG. 2A  also includes an operation  207  for defining the VG for the given level as a set of evenly spaced virtual lines that represent centerline locations of wires to be placed on the given level. The VG for the given level is defined such that a number of its virtual lines coincide with virtual lines of the contact level VG, such that wires placed in the given level according to the VG of the given level can provide sufficient coverage of contacts placed according to the contact level VG lines, wherein the contact level VG lines are commonly oriented with the VG lines of the given level and hence with the routing direction of wire placed in the given level. In  FIG. 2B , a VG for source/drain CON shapes  140 ,  141 , and  144  includes virtual lines  180 ,  182 ,  184 ,  186 , and  188 . It should be appreciated that source/drain CON shapes  140 ,  141 , and  144  are electrically connected to active region  120 . A VG for MET 1  level shapes  170 - 178  includes VG lines  180 - 188 . Because the MET 1  level shapes are related (i.e., connect) to the source/drain CON shapes ( 140 ,  141 ,  144 ) and/or to the gate CON shapes ( 142 ,  143 ), the VG for the MET 1  level includes both the virtual lines ( 181 ,  183 ,  185 ,  187 ) of the gate CON VG, and the virtual lines ( 180 ,  182 ,  184 ,  186 ,  188 ) of the source/drain CON VG. A VG for gate level shapes  200 - 203  includes VG lines  181 ,  183 .  185 , and  187 . Because the gate level shapes ( 200 - 203 ) are related (i.e., connect) to the gate CON shapes ( 142 ,  143 ), the VG for the gate level includes the virtual lines ( 181 ,  183 ,  185 ,  187 ) of the gate CON VG. As shown in  FIG. 2B , the VG for the gate level is defined by parallel virtual lines ( 181 ,  183 ,  185 ,  187 ) spaced at a line-to-line pitch P 1 . 
     The method of  FIG. 2A  further includes an operation  209  for determining whether or not the line-to-line spacing of the VG for the given level allows for enforcement of the dynamic array architecture within the given level so as to ensure optimal manufacturability of shapes in the given level. Examples of sub-optimal VG pitches include, but are not limited to: 1) a VG pitch that may be too large for shapes placed in accordance therewith to provide sufficient lithographic reinforcing benefits to each other, or 2) a VG pitch that may be too small to identify shape placements in accordance therewith, such that shapes are sufficiently regularly spaced and/or such that shapes are positioned for optimal lithography or manufacturing. If the VG pitch for the given level is acceptable, the method proceeds with an operation  214  in which the VG is recorded on a data storage device  216 . However, if the VG pitch for the given level is NOT acceptable, the method proceeds with an operation  213 . In operation  213 , an adjustment is made to the VG of one or more of the related contact levels as previously identified in operation  203 . Following operation  213 , the method reverts back to operation  207 . 
     With reference back to the exemplary embodiment of  FIG. 1 , each space SS between the long edges of neighboring gate wires  110 - 118  and  160 - 162  is substantially equivalent. Such consistency in long edge-to-long edge spacing may be beneficial to manufacturing results. However, since the widths W 1  and W 2  of the gate wires are not equal, use of the substantially equivalent long edge-to-long edge spacing SS causes some gate wire centerlines to be placed off of the virtual lines  100 - 103  of the gate level VG. For example, centerlines of shape  160  (having the non-standard width W 2 ) and shapes  115  and  116  therebelow are not aligned with the VG lines  101 - 103 , respectively. Similarly, in this example, centerlines of shape  161  (having the non-standard width W 2 ) and shapes  102  and  103  therebelow are not aligned with the VG lines  101 - 103 , respectively. Therefore, in this embodiment, gate wire shapes below VG line  100  are not placed so as to have their respective centerlines align with a VG, and consequently do not comply with the dynamic array architecture attribute regarding placement of linear features according to a VG within a given layout area, wherein the VG is defined by a set of parallel virtual lines spaced according to a substantially constant line-to-line pitch. Additionally, because the gate wire shapes below VG line  100  do not comply with the dynamic array architecture attribute regarding placement of linear features according to a VG within a given layout area, definition of the gate wire shapes below VG line  100  may not be optimal for manufacturing or layout efficiency. 
       FIG. 3A  is an illustration showing a flowchart of a method for placement of shapes such that the impact of using irregular wires in conjunction with the dynamic array architecture may be minimized, and re-alignment to a VG occurs for regular shapes outside of a layout region where there are irregular wires. The method includes an operation  3 A 01  in which a first irregular wire is placed next to a first regular wire. It should be understood that numerical designations used for particular wires, e.g., “first” irregular wire, “first” regular wire, etc., do not denote absolute wire position within a layout, but rather are used to differentiate between wires. Determination of the distance between facing long edges of the first irregular wire and the first regular wire may be based on one or more of the following considerations: 1) making such a distance substantially equivalent to a standard distance between adjacent facing long edges of regular wires, 2) providing sufficient room for a dummy shape or a sub-res shape to be inserted between the first irregular wire and the first regular wire, 3) using a distance that enables even spacing between centerlines of irregular wires within the irregular wire layout region, 4) using a distance that enables even spacing between facing long edges of adjacently placed irregular wires within the irregular wire layout region, 5) forcing irregular wires to be centered on a VG line, or 6) enabling some other desired spacing pattern for layout shapes within the irregular wire layout region, among others. The first irregular wire may belong to a group of N irregular wires that are parallel and adjacent, or it may be a solitary irregular wire with regular wires placed parallel and adjacent to both long edges of the solitary irregular wire. It should be understood that in the case of a solitary wire placed within the irregular wire layout region (N=1), the first and last irregular wire mentioned in the method of  FIG. 3A  refer to the same irregular wire. 
     The method also includes an operation  3 A 02  in which a calculation is made of a number of VG routing lines within the distance required to fit all remaining irregular wires parallel to the first irregular wire. In one embodiment, the calculation of operation  3 A 02  takes into account the space required to allow a regular wire to be placed on a VG line beyond the area with irregular wires. The method also includes an operation  3 A 03  in which a second regular wire is placed with it&#39;s centerline co-linear with a first available VG line beyond the VG line required to place the N-th irregular shape, as calculated in operation  3 A 02 . In the decision operation  3 A 05 , if the number of parallel irregular wires is greater than one (N&gt;1), the method continues with an operation  3 A 07 . 
     In the operation  3 A 07 , a last irregular wire is placed adjacent (albeit spaced apart from) and parallel to the second regular wire. Determination of the distance between facing long edges of last irregular wire and second regular wire may be based on placement considerations for the irregular wire such as those considerations described for operation  3 A 01 . The method continues with an operation  3 A 09  in which all other irregular wires between the first and last irregular wires are placed. Operation  3 A 09  may involve placement considerations similar to those described for operation  3 A 01 . 
     From the operation  3 A 09 , the method proceeds with an operation  3 A 11 . Also, with reference back to the decision operation  3 A 05 , if the number of parallel irregular wires is one (N=1), the method proceeds to operation  3 A 11 . In the operation  3 A 11 , an evaluation is made regarding the use of sub-res shapes, which may provide lithographic reinforcement to shapes in their vicinity, thereby resulting in improved manufacturing results. If the evaluation of operation  3 A 11  determines that sub-res shapes are not to be used, the method proceeds with an operation  3 A 14  for recording the layout on the data storage device  216 . If the evaluation of operation  3 A 11  determines that sub-res shapes are to be used, the method proceeds to an operation  3 A 13 , in which sub-res shapes are formed and placed. Sub-res shape formation is the determination of the polygonal outline of a sub-res shape. Sub-res shape placement may be in spaces adjacent to long edges of irregular or regular wires and may be influenced by considerations for optimal spacing, as described in conjunction with operation  3 A 01 . Following the completion of operation  3 A 13 , the method proceeds with the operation  3 A 14  for recording the layout on the data storage device  216 . 
     It should be understood that for parallel and adjacent placement of more than one successive irregular wire, the method described in  FIG. 3A  has an operational order that provides for regular wire bracketing of the region of irregular wires, prior to placement of multiple irregular wires. This operational order facilitates calculation of where to place the last irregular wire (operation  3 A 07 ), and other irregular wires between the first and last irregular wires. In addition to the foregoing, however, it should be understood that the various operations of the method of  FIG. 3A  may be performed in a non-sequential order in some embodiments. Additionally, it should be understood that the method of  FIG. 3A  represents one exemplary method for achieving the layout features and principles illustrated in the figures herein. It should be appreciated that other methods, including variants of the method of  FIG. 3A , may be utilized to achieve the layout features and principles illustrated in the figures herein. Moreover, it should be understood that the methods described herein and the layouts defined in accordance with those methods are not restricted to a particular VG or to a particular wire routing direction. Specifically, the methods described herein can be applied to a layout region of any chip level and can be implemented using either a vertically oriented VG or a horizontally oriented VG. 
     In one embodiment, an optimal spacing between facing long edges of a regular wire and an irregular wire, or between facing long edges of two adjacent irregular wires, is determined by maximizing the number of times that these long edge-to-long edge spacings are equal to a standard spacing. In this embodiment, the standard spacing is defined as a distance measured perpendicularly between facing long edges of adjacent and parallel regular wires. 
       FIG. 3B  is an illustration showing an exemplary layout defined in accordance with the method of  FIG. 3A  in which one irregular wire  360  is placed (N=1) such that a standard long edge-to-long edge spacing SS is used between one long edge of the irregular wire and a facing edge thereto of an adjacent and parallel regular wire  320 . In the exemplary layout of  FIG. 3B , each of regular wires  310 - 314 ,  320 ,  323 , and  324  having width W 1  is placed in a centered manner on a respective virtual line  300 - 304  of a VG. Adjacent virtual lines  300 - 304  of the VG are spaced at a substantially constant pitch P 1 . The single irregular wire  360  has a width W 2  and is placed such that the spacing from a first of its long edges to the facing long edge of the parallel and adjacent regular wire  320  is set to the standard spacing SS. As a result, the distance between a second long edge of the irregular wire  360  (opposite to the first long edge) and a facing long edge thereto of the adjacent and parallel regular wire  323  may be non-standard, as illustrated by non-standard spacing S 3 B 1  in  FIG. 3B . A spacing variation (SV 3 B) in this example is defined as a difference between the non-standard spacing S 3 B 1  and the standard spacing SS, i.e., SV 3 B=S 3 B 1 −SS. 
     In  FIG. 3B , regular wire  323  and regular wires below it, such as regular wire  324 , are centered on a VG virtual line. In other words, regular wires can be re-aligned to the VG beyond the irregular wire layout region within which the irregular wires are placed. Also, re-alignment of regular wires to the VG may commence at a first virtual line instance of the VG that is a sufficient distance away from an outer irregular wire, wherein the outer irregular wire is peripherally placed within the irregular wire layout region. If the irregular wire layout region contains one irregular wire, then the one irregular wire is considered a peripherally placed irregular wire, and hence an outer irregular wire. If the irregular wire layout region contains two irregular wires, then each of the two irregular wires is considered a peripherally placed irregular wire, and hence an outer irregular wire. Additionally, if the irregular wire layout region includes three or more irregular wires, numbered in an adjacent sequential manner as irregular wire one through irregular wire N, then each of irregular wire one and irregular wire N is considered a peripherally placed irregular wire, and hence an outer irregular wire. Moreover, a sufficiency of the distance away from the outer irregular wire at which re-alignment of regular wires to the VG may commence can be evaluated based on whether both the outer irregular wire and the regular wire adjacent thereto are within an applicable manufacturing process window as defined by a lithographic domain of focus and exposure that yields an acceptable fidelity of both the outer irregular wire and the regular wire adjacent thereto. Based on the example of  FIG. 3B , and other examples described hereafter, is should be appreciated that the method of  FIG. 3A  provides a beneficial effect of limiting a size of the irregular wire layout region within a given level. 
     As shown in  FIG. 3B , line ends of shapes on different VG lines may or may not be aligned. For example, line ends of wires  311  and  312  are not aligned, but line ends of wires  313  and  314  are aligned. Furthermore, a distance between facing line ends of wires which overlie a common virtual line of the VG, i.e., end gap, may or may not be constant. For example, an end gap LE 3 B 1  between facing line ends of wires  310  and  320  is different than an end gap LE 3 B 2  between facing line ends of wires  311  and  360 . It should be understood that unless otherwise specified, end gaps and alignments between line ends of adjacent parallel wires, as illustrated in the embodiments herein, are provided by way of example and do not imply a restriction on end gaps or line end alignments. Also, it should be understood that unless otherwise specified, irregular wire widths as illustrated in the exemplary embodiments herein do not imply a restriction or requirement with regard to irregular wire widths or relationships therebetween. 
       FIG. 3C  is an illustration showing an exemplary layout defined in accordance with the method of  FIG. 3A  in which multiple irregular wires  360  and  362  (N&gt;1) are placed such that a standard long edge-to-long edge spacing SS is used between one long edge of each of the irregular wires  360  and  362  and a facing edge thereto of an adjacent and parallel regular wire  320  and  324 , respectively. Thus, the exemplary layout of  FIG. 3C  has a standard gap SS between long edges of first and last irregular wires  360  and  362  and facing long edges of regular wires  320  and  324 , respectively. In  FIG. 3C , the two irregular wires  360  and  362  (N=2) have irregular widths W 2  and W 3 , respectively. Use of the standard gap SS outboard of both the first and last irregular wires  360  and  362  with N=2 results in only one irregular spacing S 3 F 1  and a spacing variation SV 3 F=S 3 F 1 −SS. 
     In one embodiment, optimal spacing between facing long edges of adjacent regular and irregular wires and/or between facing long edges of adjacent irregular wires within an irregular wire layout region is based on minimization of differences between these long edge-to-long edge spacings within the irregular wire layout region.  FIG. 3D  is an illustration showing an exemplary layout defined in accordance with the method of  FIG. 3A  in which optimal spacing between facing long edges of adjacent regular and irregular wires and between facing long edges of adjacent irregular wires within an irregular wire layout region is based on minimization of differences between these long edge-to-long edge spacings within the irregular wire layout region. In the exemplary layout of  FIG. 3D , the long edges of wires  360  and  362  are separated from facing long edges of regular wires  320  and  324 , respectively, by spacings S 3 G 1  and S 3 G 3 , which is not equal to the standard spacing SS. This forces a reduction in a space S 3 G 2  between irregular wires  360  and  362 , as compared to the corresponding spacing S 3 F 1  between irregular wires  360  and  362  in  FIG. 3C . It is possible to make each of long edge-to-long edge spacings S 3 G 1 , S 3 G 2 , and S 3 G 3  more similar to the standard spacing SS than long edge-to-long edge spacing S 3 F 1  from  FIG. 3C . 
       FIG. 3D  illustrates how a maximum spacing variation SV 3 G for the irregular wire layout region may be reduced by minimizing differences between the long edge-to-long edge spacings within the irregular wire layout region, wherein SV 3 G=MAX(S 3 G 1 ,S 3 G 2 ,S 3 G 3 )−SS. Generally speaking, maximum spacing variation within an irregular wire layout region is minimized when long edge-to-long edge spacings within the irregular wire layout region are equalized. For example, in the embodiment of  FIG. 3D , the maximum spacing variation SV 3 G within the irregular wire layout region is minimized when long edge-to-long edge spacings within the irregular wire layout region are equal, i.e., when S 3 G 1 =S 3 G 2 =S 3 G 3 . It should be appreciated that reduction of maximum or average spacing variation in an irregular wire layout region may be beneficial to manufacturing. 
     In another embodiment, optimal definition and placement of irregular wires within an irregular wire layout region may require that a spacing between facing long edges of adjacent regular and irregular wires and/or between facing long edges of adjacent irregular wires within the irregular wire layout region be based on criteria other than minimization of differences between the long edge-to-long edge spacings within the irregular wire layout region. Consequently, optimal definition and placement of irregular wires within an irregular wire layout region may require that a number of long edge-to-long edge spacings within the irregular wire layout region be intentionally defined different from a standard long edge-to-long edge spacing. For example, due to non-standard widths of irregular wires or other considerations, the optimum spacing between a long edge of an irregular wire and a facing long edge of an adjacent wire (regular or irregular) may not be the same as the standard spacing between facing long edges of two adjacent regular wires. For example, in the embodiment of  FIG. 3D , the optimum long edge-to-long edge spacings S 3 G 1 , S 3 G 2 , S 3 G 3  within the irregular wire layout region may be set according to irregular wire spacing optimization criteria other than minimization of the maximum spacing variation SV 3 G within the irregular wire layout region. 
     In one embodiment, spacing variation may be reduced by increasing the number N of parallel and adjacently placed irregular wires within the irregular wire layout region. Increasing the number N of irregular wires may reduce spacing variation for certain values of irregular wire width and long edge-to-long edge wire spacing within the irregular wire layout region, including spacings between facing long edges of adjacent regular and irregular wires and between facing long edges of adjacent irregular wires within the irregular wire layout region. A long edge-to-long edge spacing adjustment to be applied across an irregular wire layout region, to enable centering of two regular wires on respective virtual lines of the VG bordering the irregular wire layout region, can be shared among more long edge-to-long edge wire spaces within the irregular wire layout region when the number N of irregular wires is increased. Therefore, increasing the number N of irregular wires within the irregular wire layout region may reduce a magnitude of individual wire spacing adjustment within the irregular wire layout region that is necessary to minimize spacing variation. 
       FIG. 3E  is an illustration showing an exemplary layout that demonstrates how spacing variation can be reduced by increasing the number N of irregular wires within an irregular wire layout region. Irregular wires  360 - 362  are placed in a first irregular wire layout region within which an equal long edge-to-long edge wire spacing S 3 J 1  is utilized. Irregular wires  370 - 371  are placed in a second irregular wire layout region within with an equal long edge-to-long edge wire spacing S 3 J 2  is utilized. In the exemplary layout of  FIG. 3E , each of irregular wires  360 - 362  and  370 - 371  has a width W 2 . Equal irregular wire spacings (S 3 J 1  and S 3 J 2 , respectively) and equal irregular wire width (W 2 ) are utilized in the exemplary layout of  FIG. 3E  for ease of description. However, it should be understood that use of an equal irregular wire spacing and use of an equal irregular wire width is not a pre-requisite for implementing the embodiment in which spacing variation is reduced by increasing the number N of irregular wires within an irregular wire layout region. 
     A term NVG is defined as a number of virtual lines of the VG that are located between the two regular wires which bound the irregular wire layout region. For the first irregular wire region including irregular wires  360 - 362 , NVG equals 4 and includes virtual lines  301 - 304 . For the second irregular wire region including irregular wires  370 - 371 , NVG equals 3 and includes virtual lines  301 - 303 . In the example of  FIG. 3E , a standard spacing SS between regular wires is defined as SS=P 1 −W 1 , wherein P 1  is the VG pitch and W 1  is a width of the regular wires ( 310 - 315 ,  320 ,  325 ,  330 ,  334 ). For each irregular wire layout region, irregular spacing S 3 Jn=((NVGn+1)*P 1 −W 1 −Nn*W 2 )/(Nn+1), wherein (n) identifies the irregular wire layout region. For the first irregular wire layout region (n=1) including irregular wires  360 - 362 , N 1 =3 and NVG 1 =4, thereby yielding irregular spacing S 3 J 1 =(5P 1 −W 1 −3*W 2 )/4. For the second irregular wire layout region (n=2) including wires  370 - 371 , N 2 =2 and NVG 2 =3, thereby yielding irregular spacing S 3 J 2 =(3P 1 −W 1 −2*W 2 )/3. For discussion purposes consider that W 2 =2*W 1  and P 1 =3*W 1 . Then, SS=2*W 1 , S 3 J 1 =2*W 1 , and S 3 J 2 , (4/3)*W 1 . For the first irregular wire layout region, spacing variation SVR 1 =SS−S 3 J 1 =0. For the second irregular wire layout region, spacing variation SVR 2 =SS−S 3 J 2 , (2/3)*W 1 . Therefore, the exemplary layout of  FIG. 3E  demonstrates how an increase in the number N of irregular wires within an irregular wire layout region serves to reduce spacing variation. 
       FIG. 3F  is an illustration showing a variant of the exemplary layout of  FIG. 3B , defined in accordance with the method of  FIG. 3A , in which one irregular wire  360  is placed (N=1) in conjunction with a sub-res wire  390  within the irregular wire layout region. The sub-res wire  390  is defined to have a width SRW, and is placed between irregular wire  360  and regular wire  323 . Use of the sub-res wire  390  eliminates the large wire spacing S 3 B 1 , as shown in  FIG. 3B , and introduces smaller wire spacings S 3 D 1  and S 3 D 2 . It should be noted that as compared to wire spacing S 3 B 1 , both of wire spacings S 3 D 1  and S 3 D 2  are closer to the standard spacing SS. Therefore, use of the sub-res wire  390  improves on the embodiment described in  FIG. 3B  in that spacing variation is reduced, which may be beneficial to manufacturing. 
       FIG. 3G  is an illustration showing a variant of the exemplary layout of  FIG. 3C , defined in accordance with the method of  FIG. 3A , in which two irregular wires  360  and  362  are placed (N=2) in conjunction with a sub-res wire  391  within the irregular wire layout region. The sub-res wire  391  is defined to have a width SRW, and is placed between irregular wire  360  and irregular wire  362 . Use of the sub-res wire  391  eliminates the large wire spacing S 3 F 1 , as shown in  FIG. 3C , and introduces smaller wire spacings S 3 E 2  and S 3 E 3 . It should be noted that as compared to wire spacing S 3 F 1 , both of wire spacings S 3 E 2  and S 3 E 3  are closer to the standard spacing SS. Therefore, use of the sub-res wire  391  improves on the embodiment described in  FIG. 3C  in that spacing variation is reduced, which may be beneficial to manufacturing. 
     It should be understood that the methods and layout techniques disclosed herein can be applied to any chip level.  FIG. 4  shows an exemplary layout for a diffusion level, defined in accordance with the method of  FIG. 3A . In one embodiment, layout shapes shown in  FIG. 4  correspond to doped silicon regions, and may be referred to as active shapes or diffusion shapes. A VG for the diffusion level is defined by virtual lines  400 - 404 . A number of regular diffusion shapes  410 - 414 ,  420 ,  424 ,  430 , and  434  are defined to have standard width W 41 , and are placed with a standard spacing S 40 . Irregular diffusion shape  460  of width W 42  is placed such that the standard spacing S 40  exists between its outboard long edge and a facing long edge of adjacent regular diffusion shape  420 . In one embodiment, a vacant irregular spacing S 44  exists between facing long edge of irregular diffusion shape  460  and regular diffusion shape  424 . In another embodiment, a sub-res shape  430  is inserted between irregular diffusion shape  460  and regular diffusion shape  424 , resulting in irregular spacings S 41  and S 42 . As compared to irregular spacing S 44 , irregular spacings S 41  and S 42  may be more similar to standard spacing SS, thereby providing a reduced spacing variation as compared to the embodiment without the sub-res shape  430 . In another embodiment, multiple irregular diffusion shapes  461  and  462  are placed between parallel regular diffusion shapes  430  and  434 . In this embodiment, spacings extending perpendicularly away from long edges of irregular diffusion shapes  461  and  462  are shown as S 43 , S 44 , and S 45 . In one embodiment, spacings S 43 -S 45  are made similar or equal to each other to reduce the maximum spacing variation between standard spacing S 40  and spacings S 43 -S 45 . 
     In some embodiments an irregular wire width may be smaller than a standard wire width.  FIG. 5A  shows an exemplary layout in which irregular wires  660 - 664  have non-standard widths W 60 -W 64 , which may or may not be equal to each other and which are smaller than a standard width W 6  for regular wires  610 - 615 ,  620 , and  625 . A standard spacing SS 6  is defined between facing long edges of adjacent regular wires  610 - 615 . In  FIG. 5A , irregular wires  660 - 664  are placed to maximize the occurrence of standard spacing SS 6  within the irregular wire layout region. Generally speaking, the number N of irregular wires in an irregular wire layout region, and the respective widths thereof, may be defined such that for a given VG pitch it is not possible to place each irregular wire to have long edge-to-long edge spacings equivalent to the standard spacing. For example, the number N=5 of irregular wires  660 - 664  in the irregular wire layout region of  FIG. 5A , and the respective widths thereof W 60 -W 64 , may be defined such that for a given VG (virtual lines  600 - 605 ) of pitch P 6  it is not possible to place each irregular wire  660 - 664  to have long edge-to-long edge spacings equivalent to the standard spacing SS 6 . Spacing of irregular wires  660 - 664  to maximize the occurrence of standard spacing SS 6  results in a single non-standard spacing S 6 A 1  between facing long edges of adjacently placed irregular wires  662  and  663 . A spacing variation SV 6 A 1  for the dimension S 6 A 1  is expressed as: SV 6 A 1 =S 6 A 1 −SS 6 . 
       FIG. 5B  shows an exemplary layout similar to that of  FIG. 5A  except that irregular wires  660 - 664 , having widths W 60 -W 64  that are less than standard width W 6 , are placed such that long edge-to-long edge spaces S 6 B 1 -S 6 B 6  associated with irregular wires  660 - 664  are defined to be similar to each other, but not necessarily equal to the standard spacing SS 6 . Maximum spacing variation (SV 6 B=|MAX(S 6 B 1 ,S 6 B 2 ,S 6 B 3 ,S 6 B 4 ,S 6 B 5 ,S 6 B 6 )−SS 6 |) may be minimized for this exemplary layout when irregular spacings S 6 B 1  through S 6 B 6  are equalized. With equal irregular spacings S 6 B 1  through S 6 B 6 , the maximum spacing variation SV 6 B can be expressed as: SV 6 B=|S 6 B 1 −SS 6 |. This spacing variation SV 6 B may be less than the maximum spacing variation SV 6 A for the layout of  FIG. 5A , because the extra space required to re-synchronize regular wires to the VG at the boundary of the irregular wire layout region is spread among all irregular spacings S 6 B 1 -S 6 B 6  in the irregular wire layout region of  FIG. 5B , whereas the extra space required to re-synchronize regular wires to the VG at the boundary of the irregular wire layout region is focused in the irregular spacing S 6 A 1  between the two irregular wires  662  and  663  in the irregular wire layout region of  FIG. 5A . It should be understood that an irregular spacing may be less than a standard spacing. For example, the irregular spacing S 6 B 1  may be less than the standard spacing SS 6  in  FIG. 5B . 
       FIG. 5C  shows an exemplary layout with irregular wires  660 - 661  having widths W 61 -W 62 , respectively, that are less than a standard width SS 6 . A sub-res wire  690  of width SRW 6  is placed between irregular wires  660  and  661 . A spacing S 6 C 1  exists between facing long edges of irregular wire  660  and regular wire  620 . A spacing S 6 C 2  exists between facing long edges of irregular wire  660  and sub-res wire  690 . A spacing S 6 C 3  exists between facing long edges of sub-res wire  690  and irregular wire  661 . A spacing S 6 C 4  exists between facing long edges of irregular wire  661  and regular wire  623 . Use of the sub-res wire  690  avoids having a large irregular spacing between irregular wires  660  and  661 , and thereby enables reduction in spacing variation, which may be beneficial to manufacturing. Also, the width SRW 6  of sub-res wire  690  is somewhat adjustable so long as the sub-res wire  690  does not resolve during a manufacturing process. Therefore, in one embodiment, the irregular spacings S 6 C 1 -S 6 C 4  may be set equal to the regular spacing SS 6 , if the width SRW 6  of sub-res wire  690  can be correspondingly adjusted without causing resolution of the sub-res wire  690 . 
     A method to reduce negative electrical or manufacturing influences between layout shapes or layout regions is to interpose other layout shapes between them. These interposing layout shapes may have characteristics of regular wires, irregular wires, or sub-res wires and may provide protection between regions of irregular wires and regions of regular wires.  FIG. 6  shows an exemplary layout implementing the above-mentioned method.  FIG. 6  shows irregular wires  760  and  761  and regular wires  710 - 715 ,  721 ,  722 ,  724 ,  725 ,  730 - 725 . An irregular wire layout region is defined between regular wires  722  and  724 . Irregular spacings S 7 A 1 -S 7 A 3  are utilized within the irregular wire layout region. The regular wire  722  is placed adjacent to irregular wire  760 . Because the regular wire  722  may shield regular wire  721  from lithographic and/or electrical influences (such as adverse light wave interference and/or capacitive coupling) of irregular wire  760 , the regular wire  722  is considered a protective shape. The long regular wire  724  is placed adjacent to irregular wire  761 . Similarly, because the long regular wire  724  may shield regular wire  725  from the lithographic and/or electrical influences of irregular wire  761 , the long regular wire  724  is considered a protective shape. Linear layout shapes may also by defined to perform an isolating or protecting function for other layout shapes in a direction of extent of the VG. For example, regular wires such as  712 - 713  may prevent unwanted lithographic or electrical interactions between layout shapes or layout regions adjacent to their left edges, i.e., to their left wire ends, and irregular wires  760  and  761 , which are adjacent to the right wire ends of regular wires  712 - 713 . 
     Another method to increase the effectiveness of placing a protective layout shape between layout shapes or layout regions includes ensuring that the protective layout shape is unbroken (does not have gaps) and/or that it extends beyond a boundary of a layout shape/region to be protected and in the direction parallel to VG lines. For example, in the exemplary layout of  FIG. 6 , the protective long regular wire  724  extends beyond the line end of irregular wire  761  by a distance of DWEXT. In this manner, undesired interactions, such as adverse lithographic and/or electrical influences, between irregular wire  761  and regular wires  715  and  725  are further reduced. 
     Another method to reduce negative manufacturing influences between layout shapes or layout regions is to interpose sub-res shapes between them, such that the interposing sub-res shapes act as protective shapes.  FIG. 7  shows a variation of the exemplary layout of  FIG. 6  in which protective sub-res shapes  790  and  791  are placed in lieu of protective regular wires  722  and  724 , respectively. In the exemplary layout of  FIG. 7 , an irregular wire layout region is defined between regular wires  721  and  725 , to include irregular wires  760 - 761  and sub-res shapes  790 - 791 . Each of sub-res shapes  790  and  791  is defined to have a width of SRW. Sub-res shape  790  is separated from adjacent regular wire  721  by the standard spacing SS. Irregular wire  760  is separated from sub-res shape  790  by irregular spacing S 7 B 1 . Irregular wire  761  is separated from irregular wire  760  by irregular spacing S 7 B 2 . Sub-res shape  791  is separated from irregular wire  761  by irregular spacing S 7 B 3 . Sub-res shape  791  is also separated from regular wire  725  by standard spacing SS. Sub-res shape  790  may reduce lithographic influences between layout shapes  721  and  760 . Similarly, sub-res shape  791  may reduce lithographic influences between layout shapes  725  and  761 . 
     Another method to improve the manufacturability of a layout that includes irregular wires is to optimize end gaps associated with specific wire widths, wherein the optimized end gaps may vary in size within the layout.  FIG. 8A  shows an exemplary layout within which end gaps are varied to improve manufacturability.  FIG. 8A  shows irregular wires  860 - 863 , surrounded by regular wires  810 - 815 ,  820 ,  821 ,  824 ,  825 ,  830 ,  831 ,  834 ,  835 ,  841 - 845 . In the example embodiment of  FIG. 8A , regular wires placed end-to-end that are not adjacent to the irregular wire layout region, such as regular wires  810  and  820 , have a standard end gap LS 1  between their facing line ends. Regular wires placed end-to-end with irregular wires of the irregular wire layout region, such as regular wires  812  and  813  respectively placed end-to-end with irregular wires  860  and  861 , may have a non-standard end gap LS 2  between their facing line ends. Similarly, regular wires  842  and  843  placed end-to-end with irregular wires  862  and  863 , respectively, have a non-standard end gap LS 5  between their facing line ends. Also, irregular wires placed end-to-end within the irregular wire layout region, such as irregular wires  860  and  862 , may have a another non-standard end gap LS 3  between their facing line ends. Also, regular wires that bound the irregular wire layout region, such as regular wires  821  and  831 , may have another non-standard end gap LS 4  between their facing line ends. It should be understood that non-standard end gaps, such as LS 2 -LS 5 , may be defined to provide lithographic compensation or optimization necessitated by definition and placement of irregular wires within the irregular wire layout region. More specifically, particular irregular wire dimensions (width and length) and irregular wire spacings (end gap and long edge-to-long edge) within the irregular wire layout region may steer definition of non-standard end gaps within and/or around the irregular wire layout region. 
     For circuits that need to be matched in terms of manufactured shape characteristics and in terms of electrical influences due to neighboring elements, such as balanced circuits, use of protective layout shapes around such circuits may be combined with use of irregular wires and/or irregular spaces within such circuits to provide the necessary matching therebetween. Layout shapes within circuits to be matched may also be arranged symmetrically in X rows and Y columns. Such a symmetric arrangement may be done for structures such as common centroid structures or other circuits that require close matching between shape dimensions such as gate length and width. Also, it should be appreciated that use of protective layout shapes within and/or around a circuit layout may serve to reduce unwanted electrical coupling effects and/or unwanted lithographic interactions between layout shapes on either side of the protective layout shapes in any given direction. 
     In the exemplary embodiment of  FIG. 8A , irregular wires  860 - 863  are arranged symmetrically both vertically and horizontally, i.e., in both x- and y-directions. In one embodiment, wire placement symmetry, such as that demonstrated by irregular wires  860 - 863 , enables matching between pairs of layout shapes. For example, the combined characteristics of irregular wires  860  and  863  are matched to the combined characteristics of irregular wires  861  and  862 . In one embodiment, electrically connected circuit features, such as irregular wires  860  and  863  by way of example, are placed diagonally with respect to each other. Also, a matched pair of electrically connected circuit features, such as irregular wires  861  and  862  by way of example, are placed diagonally. Furthermore, features in the matched circuit, such as irregular wires  860 - 863 , are placed evenly around a common point in space X, also referred to a common centroid. To this end, pairs of wires in a matched circuit that are placed end-to-end, such as irregular wires  860  and  862 , and irregular wires  861  and  863 , are separated by the same end gap LS 3 . Also, pairs of wires in a matched circuit that are placed adjacent and parallel to each other, such as irregular wires  860  and  861 , and irregular wires  862  and  863 , are separated by the same long edge-to-long edge spacing S 8 A 2 . 
     Regular wires which bound a symmetrically defined irregular wire layout region may be placed such that edges of the regular wires that face toward a given side of the irregular wire layout region are positioned at a constant distance from the outward facing edges of the layout shapes within and along the given side of the irregular wire layout region. For example, regular wires  812 ,  813 ,  824 ,  834 ,  843 ,  842 ,  831 , and  821  which bound the irregular wire layout region shown in  FIG. 8A , may be placed such that their edges which face toward the irregular wire layout region are a constant distance from respective facing edges of irregular wires  860 - 863  along a given side of the irregular wire layout region. For instance, edges of regular wires  812  and  813  which face toward the irregular wire layout region are a constant distance LS 2  from respective facing edges of irregular wires  860  and  861 . Edges of regular wires  824  and  834  which face toward the irregular wire layout region are a constant distance S 8 A 3  from respective facing edges of irregular wires  861  and  863 . Edges of regular wires  843  and  842  which face toward the irregular wire layout region are a constant distance LS 5  from respective facing edges of irregular wires  863  and  862 . Edges of regular wires  831  and  821  which face toward the irregular wire layout region are a constant distance S 8 A 1  from respective facing edges of irregular wires  862  and  860 . Additionally, further regularity may be achieved in the symmetrically defined irregular wire layout region if some of the peripheral spacings (LS 2 , S 8 A 3 , LS 5 , S 8 A 1 ) are made equal, e.g., LS 2 =LS 5  and/or S 8 A 1 =S 8 A 3 . It should be understood that the regular wires which bound an irregular wire layout region, (such as regular wires  811 - 814 ,  821 ,  824 ,  831 ,  834 ,  841 - 844 ) may be used as protective layout shapes and/or may be used to perform a circuit function. 
       FIG. 8B  shows an exemplary layout in which long regular wires are used to bound an irregular wire layout region, thereby serving as protective layout shapes between the irregular wire layout region and a surrounding layout area. Long regular wires  811 P and  814 P are each placed to bound a respective side of an irregular wire layout region within which irregular wires  860 - 863  are symmetrically arranged in a common centroid fashion around point X. Each of the long regular wires  811 P and  814 P is defined to extend beyond outer edges of outermost irregular wires. For example, long regular wire  814 P is defined to extend beyond an outer edge of irregular wire  863  by a distance DWEXT. The unbroken nature of the long regular wires  811 P and  814 P and their extension beyond the outer edges of the outermost irregular wires may provide protection against adverse manufacturing or electrical influences between irregular shapes  860 - 863  and regular shapes  810 ,  820 ,  830 ,  815 ,  825 ,  835 , and  845  placed on an opposing side of long regular wires  811 P and  814 P. Regular wires  812 ,  813 ,  842 , and  843  which are respectively placed end-to-end with irregular wires  860 - 863  may reduce unwanted interactions between irregular wires  860 - 863  and other layout shapes, such as layout shapes placed to the left of regular wires  812  and  813  or layout shapes placed to the right of regular wires  842  and  843 . 
     Another method to reduce unwanted lithographic interactions between two layout shapes is to interpose a sub-res wire between the two layout shapes, as an alternative to the previously described method of interposing regular wires. Because the sub-res shape is not manufactured, one advantage of using a sub-res shape is that capacitive coupling between manufactured shapes that are separated by the sub-res shape is reduced. Therefore, a conductor-to-conductor separation distance associated with facing edges of two manufactured shapes is increased when a sub-res shape is used as an interposed protective layout shape, relative to when a regular wire is used as the interposed protective layout shape.  FIG. 8C  shows a variation of the exemplary layout of  FIG. 8B , in which sub-res shapes  890  and  891  are used in lieu of long regular wires  811 P and  814 P, respectively. Each of sub-res shapes  890  and  891  is defined to have a width SRW, such that the sub-res shape will not resolve during manufacturing. The sub-res shape  890  reduces lithographic interaction between the irregular wires  860 - 863  and the regular wires  810 ,  820 ,  830  that are placed opposite the sub-res shape  890  from the irregular wire layout region. The sub-res shape  891  reduces lithographic interaction between the irregular wires  860 - 863  and the regular wires  815 ,  825 ,  835 ,  845  that are placed opposite the sub-res shape  891  from the irregular wire layout region. In the portion of the as-manufactured chip level associated with the layout of  FIG. 8C , a large space SMANUF is present between the facing long edges of regular wire  820  and irregular wire  860 , and between the facing long edges of regular wire  830  and irregular wire  862 . It should be appreciated that the space SMANUF is larger that a long edge-to-long edge spacing S 8 B 1  between the regular wire  811 P and the irregular wires  860  and  862  in the layout of  FIG. 8B . Therefore, the capacitive coupling experienced by irregular wires  860  and  862  may be reduced by the larger conductor-to-conductor spacing SMANUF, relative to the spacing S 8 B 1 . 
     The use of protective layout shapes may also be helpful in preventing unwanted interactions between an area of higher layout shape density and an area of lower layout shape density, as variations in layout shape density may adversely affect lithographic results.  FIG. 8D  shows a layout region  1199  immediately adjacent to a long edge  1114 A of a linear layout shape  1114 . Layout shape  1114  may protect layout shapes placed opposite the layout shape  1114  from the layout region  1199 , such as layout shapes  1160 - 1163 , from adverse lithographic effects related to layout shapes within layout region  1199 . In one embodiment, layout region  1199  may have a lower layout shape density relative to the layout region defined opposite the linear layout shape  1114 . For example, a long edge-to-long edge spacing S 114 , between linear layout shape  1114  and adjacently placed layout shape  1170  within the layout region  1199 , may be significantly larger than long edge-to-long edge spacings S 113  and S 112  within the layout region defined opposite the linear layout shape  1114 . The lithographic influence of region  1199  on wires  1161  and  1163  may be reduced by the presence of linear layout shape  1114  acting as a protective layout shape. 
     The use of regular wires and sub-res shapes as protective layout shapes, such as described with regard to  FIGS. 8B and 8C , can be applied to protect either regular wires or irregular wires.  FIG. 8E  shows an exemplary layout in which regular wires  880 - 883  of standard width W 1  are defined within a layout region R 8 D. Protective layout shapes  890 ,  891 ,  812 ,  813 ,  842 , and  843  serve to protect regular wires  880 - 883  from adverse lithographic and/or electrical influence by layout shapes/regions defined outside of the layout region R 8 D. It should be appreciated that some or all of protective layout shapes  890 ,  891 ,  812 ,  813 ,  842 , and  843  may be sub-res shapes. 
     Layout shapes can be arranged in a number of ways to optimize circuit balancing.  FIG. 8F  shows an exemplary layout that includes a symmetrical arrangement of irregular wires  860 - 863 . Top edges of irregular wires  860  and  862  are substantially aligned with, or near to aligned with, top edges of neighboring regular wires  830  and  841 , thereby resulting in a long edge-to-long edge spacing S 8 E 1  between regular wire  810 P and each of irregular wires  860  and  862  that is substantially equivalent to standard spacing SS. Bottom edges of irregular wires  861  and  863  are substantially aligned with, or near to aligned with, bottom edges of neighboring regular wires  813  and  843 , thereby resulting in a long edge-to-long edge spacing S 8 E 2  between regular wire  814 P and each of irregular wires  861  and  863  that is substantially equivalent to standard spacing SS. Spacing S 8 E 5  between facing long edges of irregular shapes such as  860  and  861  may not be equivalent to or near the standard spacing SS. Although similar to the exemplary layout of  FIG. 3C , the exemplary layout of  FIG. 8F  includes a common centroid style irregular wire layout arrangement. 
       FIG. 8G  shows a variation of the exemplary layout of  FIG. 8F  in which a layout shape  822 P is inserted between symmetrically arranged irregular wires  860 - 863 . Layout shape  822 P may be a dummy shape or may be used for a circuit function. A width W 3  of layout shape  822 P may be regular, irregular, or small enough that the layout shape  822 P is a sub-res shape. Facing long edges of irregular wire  860  and layout shape  822 P are separated by spacing S 8 F 3 . Similarly, facing long edges of irregular wire  862  and layout shape  822 P are separated by spacing S 8 F 3 . Facing long edges of irregular wire  861  and layout shape  822 P are separated by spacing S 8 F 4 . Similarly, facing long edges of irregular wire  863  and layout shape  822 P are separated by spacing S 8 F 4 . The spacings S 8 F 3  and S 8 F 4  may be closer to standard spacing SS than the spacing S 8 E 5  in the layout of  FIG. 8F , in which the interposing shape  822 P is not present. 
     Although the exemplary layouts depicted in  FIGS. 8A-8G  include irregular wire layout regions arranged in two rows and two columns around a common center point (common centroid), it should be understood that the irregular wires in the irregular wire layout region can be arranged in essentially any manner. For example, in various embodiments, the irregular wires in the irregular wire layout region can be arranged in an array defined by a variable number of layout shape columns and a variable number of layout shape rows. 
       FIG. 8H  shows an exemplary layout in which irregular wires  870 - 873  are arranged in an array defined by four layout shape columns and one layout shape row. In one embodiment, matching is required between interleaved pairs of irregular wires such that the combined characteristics of irregular wires  870  and  872  are matched to the combined characteristics of irregular wires  871  and  873 . The exemplary layout of  FIG. 8H  also includes protective shapes defined by wires  890 ,  891 ,  812  and  842 , which reduce lithographic and/or electrical interactions between irregular wires  870 - 873  and regular wires opposite the protective shapes from the irregular wire layout region, such as regular wires  810 ,  820 , and  813 . A respective width of each protective wire  890 ,  891 ,  812  and  842  may be regular, irregular, or small enough that the protective wire is a sub-res shape. Spacings S 8 H 1 -S 8 H 7  that extend perpendicularly away from long edges of irregular wires may not be equal to standard spacing SS. 
     Another method to reduce spacing variation is to modify one or more irregular wire widths such that long edge-to-long edge spacing after placement is satisfactory. This method may be used in conjunction with other methods and embodiments shown herein. One embodiment of this method is shown in  FIG. 9A , in which an irregular wire  960  is placed in an area including regular wires  910 - 913 ,  920 , and  923 . A width W 960  of irregular wire  960  is set such that spacing variations associated with the irregular wire  960  is acceptable, wherein these spacing variations are defined as the differences between standard spacing SS and each of spacings S 9 A 1  and S 9 A 2 . In one embodiment, these spacing variations are eliminated by setting the width W 960  and the placement of irregular wire  960 , such that S 9 A 1 =S 9 A 2 =SS. 
     Another embodiment is shown in  FIG. 9B , where two irregular wires  961  and  962  having widths W 961  and W 962 , respectively, are successively placed between regular wires  920  and  924 . Long edge-to-long edge spacings associated with irregular shapes  961  and  962  are shown as S 9 B 1 , S 9 B 2 , and S 9 B 3 . In one embodiment, irregular wire widths W 961  and W 962  are set such that spacing variations associated with irregular wires  961  and  962  are reduced to an acceptable value, wherein these spacing variations are defined as SV 9 B 1 =|S 9 B 1 −SS|, SV 9 B 2 =|S 9 B 2 −SS|, and SV 9 B 3 =|S 9 B 3 −SS|. In one embodiment, each of spacing variations SV 9 B 1 , SV 9 B 2 , and SV 9 B 3  can be eliminated if W 961 , W 962  and the placement of irregular wires  961  and  962  are defined such that S 9 B 1 =S 9 B 2 =S 9 B 3 =SS. 
     Another embodiment is shown in  FIG. 9C , where irregular shapes  971 ,  972 , and  990  having widths W 971 , W 972 , and W 990 , respectively, are placed between regular wires  920  and  924 . Long edge-to-long edge spacings associated with irregular wires  971 ,  990 , and  972  are shown as S 9 C 1 , S 9 C 2 , S 9 C 3 , and S 9 C 4 . Width W 990  can be set to a value less than standard width W 1  to compensate for widths W 971  and W 972  that are greater than standard width W 1 , so as to set each of spacings S 9 C 1 , S 9 C 2 , S 9 C 3 , and S 9 C 4  sufficiently similar to standard spacing SS. In one embodiment, the width W 990  may be small enough to make wire  990  a sub-res shape. In one embodiment, all spacing variation can be eliminated if W 971 , W 972 , W 990 , and the placement of shapes  971 ,  972 , and  990  are such that S 9 C 1 =S 9 C 2 =S 9 C 3 =S 9 C 4 =SS. 
     In the methods and exemplary layouts previously described, irregular wires and sub-res shapes may or may not be centered on a VG line, on which regular wires are centered. Another method for formation and placement of irregular wires includes placement of irregular wires such that centerlines of the irregular wires are coincident with VG lines to a maximum extent possible, while minimizing an impact of non-standard width wires on overall layout pattern regularity. 
       FIG. 10A  shows an exemplary layout in which an irregular wire  1030  is placed such that its centerline is coincident with a VG line  102 . Irregular wire  1030  is placed within an irregular wire region bounded by regular wires  1010 - 1014 ,  1020 , and  1024 . VG lines  101  and  103  are unpopulated within the irregular wire layout region. With each layout shape centered on VG line and with no long edge-to-long edge spacings less than standard spacing SS, placement of irregular wire  1030  on VG line  102  results in long edge-to-long edge spacings of S 10 A 1  and S 10 A 2 . In this embodiment, spacing variation (SV 10 A=|S 10 A 1 −SS|) may be significant. 
       FIG. 10B  shows a variation of the exemplary layout of  FIG. 10A  in which irregular wire  1030  is moved up to VG line  101 , and regular wire  1024  is moved up to VG line  102 . This results in non-standard spacings S 10 B 1  and S 10 B 2 , which are less than standard spacing SS. Spacing variation may be less in a layout that does not skip VG lines to accommodate irregular wire placement, as compared to a layout that does skip VG lines to accommodate irregular wire placement, such as shown in  FIG. 10A . However, where an irregular wire width is wider than the standard width of regular wires, placement of the irregular wire may result in irregular spacing that is too small to pass manufacturing design rule checks. 
       FIG. 10C  shows a variation of the exemplary layout of  FIG. 10A  in which layout shapes  1060  and  1061  are inserted in long edge spaces S 10 A 1  and  510 A 2  on each side of irregular wire  1030 . Insertion of layout shapes  1060  and  1061  creates long edge-to-long edge spacings S 10 C 1 -S 10 C 4 , which may be closer to standard spacing SS than long edge spaces S 10 A 1  and S 10 A 2 . In one embodiment, layout shapes  1060  and  1061  may be sub-res shapes. 
     It should be understood that the methods for defining an irregular wire layout region within the dynamic array architecture as disclosed herein can be implemented in a layout that is stored in a tangible form, such as in a digital format on a computer readable medium. For example, the layout defined in accordance with the methods disclosed herein can be stored in a layout data file of one or more cells, selectable from one or more libraries of cells. The layout data file can be formatted as a GDS II (Graphic Data System) database file, an OASIS (Open Artwork System Interchange Standard) database file, or any other type of data file format suitable for storing and communicating semiconductor device layouts. Also, multi-level layouts defined in accordance with the methods disclosed herein can be included within a multi-level layout of a larger semiconductor device. The multi-level layout of the larger semiconductor device can also be stored in the form of a layout data file, such as those identified above. 
     Also, the invention described herein can be embodied as computer readable code on a computer readable medium. For example, the computer readable code can include the layout data file within which one or more layouts defined in accordance with the methods disclosed herein are stored. The computer readable code can also include program instructions for selecting one or more layout libraries and/or cells that include a layout defined in accordance with the methods disclosed herein. The layout libraries and/or cells can also be stored in a digital format on a computer readable medium. 
     The computer readable medium mentioned herein is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes, and other optical and non-optical data storage devices. The computer readable medium can also be distributed over a network of coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for performing these operations. The apparatus may be specially constructed for the required purpose, such as a special purpose computer. When defined as a special purpose computer, the computer can also perform other processing, program execution or routines that are not part of the special purpose, while still being capable of operating for the special purpose. Alternatively, the operations may be processed by a general purpose computer selectively activated or configured by one or more computer programs stored in the computer memory, cache, or obtained over a network. When data is obtained over a network the data maybe processed by other computers on the network, e.g., a cloud of computing resources. 
     The embodiments of the present invention can also be defined as a machine that transforms data from one state to another state. The data may represent an article, that can be represented as an electronic signal and electronically manipulate data. The transformed data can, in some cases, be visually depicted on a display, representing the physical object that results from the transformation of data. The transformed data can be saved to storage generally, or in particular formats that enable the construction or depiction of a physical and tangible object. In some embodiments, the manipulation can be performed by a processor. In such an example, the processor thus transforms the data from one thing to another. Still further, the methods can be processed by one or more machines or processors that can be connected over a network. Each machine can transform data from one state or thing to another, and can also process data, save data to storage, transmit data over a network, display the result, or communicate the result to another machine. 
     It should be further understood that the layouts defined in accordance with the methods disclosed herein can be manufactured as part of a semiconductor device or chip. In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on a semiconductor wafer. The wafer includes integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level, transistor devices with diffusion regions are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Also, patterned conductive layers are insulated from other conductive layers by dielectric materials. 
     While this invention has been described in terms of several embodiments, it will be appreciated that those skilled in the art upon reading the preceding specifications and studying the drawings will realize various alterations, additions, permutations and equivalents thereof. Therefore, it is intended that the present invention includes all such alterations, additions, permutations, and equivalents as fall within the true spirit and scope of the invention.