Abstract:
Methods for forming an alignment mark and the resulting mark are disclosed. Embodiments may include forming a first shape having rotational symmetry; forming a second shape; and forming an alignment mark by combining the first shape and one or more of the second shape, wherein the alignment mark has rotational symmetry.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to alignment marks. The present disclosure is particularly applicable to alignment marks for semiconductor alignment and inspection purposes, and is particularly applicable to 28 nanometer (nm) technology nodes and beyond. 
       BACKGROUND 
       [0002]    Existing alignment marks can be used in kerf or prime areas on semiconductor wafers for reference during optical global alignment (OGA). Such alignment marks can be any kind of unique structure. However, it can be time consuming to find suitable structures for use in scanning electronic microscope global alignment (SEMGA), which is at relatively smaller sizes. Further, existing alignment marks cannot provide for reticle inspection alignment in a pattern area for rotation inspection or overlay measurements, such as scanning electronic microscopic overlay measurements and/or optical overlay measurements. 
         [0003]    A need therefore exists for a method of forming a general alignment mark that can be used for various purposes, and the resulting mark. 
       SUMMARY 
       [0004]    An aspect of the present disclosure is a method of forming an alignment mark capable of use in OGA, SEMGA, overlay measurement, and reticle inspection. 
         [0005]    Another aspect of the present disclosure is a substrate including an alignment mark capable of use in OGA, SEMGA, overlay measurement, and reticle inspection. 
         [0006]    Additional aspects and other features of the present disclosure will be set forth in the description which follows and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the present disclosure. The advantages of the present disclosure may be realized and obtained as particularly pointed out in the appended claims. 
         [0007]    According to the present disclosure, some technical effects may be achieved in part by a method including forming a first shape having rotational symmetry; forming a second shape; and forming an alignment mark by combining the first shape and one or more of the second shape, wherein the alignment mark has rotational symmetry. 
         [0008]    An aspect of the present disclosure includes forming the alignment mark by combining the first shape with four of the second shape. Another aspect includes placing an edge of each one of the four second shapes contiguous with a separate edge of the first shape to form the alignment mark. Yet another aspect includes the first shape being a square and the second shape being a quadrilateral. Another aspect includes forming one or more concentric outlines within the first shape corresponding to a number of levels of exposure. Yet another aspect includes forming rotationally symmetric shapes along the one or more concentric outlines corresponding to features formed in the levels of exposure. An additional aspect includes forming a cross-hatched grid of lines within the second shape corresponding to features formed in a number of levels of exposure. Still another aspect includes forming rotationally symmetric shapes at intersections of the cross-hatched grid of lines. 
         [0009]    Another aspect of the present disclosure is a device including: a substrate; and one or more rotationally symmetric alignment marks on the substrate, wherein the one or more rotationally symmetric alignment marks include: a first shape having rotational symmetry; and at least one of a second shape. 
         [0010]    Aspects include the one or more alignment marks including four of the second shape. Yet another aspect includes the one or more alignment marks including an edge of each one of the four second shapes being contiguous with a separate edge of the first shape. An additional aspect includes the first shape being a square and the second shape being a quadrilateral. Yet another aspect includes the first shape further including: one or more concentric outlines corresponding to a number of levels of exposure. Still another aspect includes the first shape further including: rotationally symmetric shapes along the one or more concentric outlines corresponding to features formed in the levels of exposure. Another aspect includes the second shape further including: a cross-hatched grid of lines corresponding to features formed in a number of levels of exposure. Yet a further aspect includes the second shape further including rotationally symmetric shapes at intersections of the cross-hatched grid of lines. 
         [0011]    Another aspect of the present disclosure is a method including: forming a first shape having 90-degree rotational symmetry; and forming at least one of a second shape, with an edge of each of the at least one second shape being contiguous with a separate edge of the first shape, forming an alignment mark, wherein the alignment mark has 90-degree rotational symmetry. 
         [0012]    An additional aspect includes forming one or more concentric outlines within the first shape corresponding to a number of levels of exposure; and forming 90-degree rotationally symmetric shapes along the one or more concentric outlines corresponding to features formed in the levels of exposure. Yet another aspect includes forming a cross-hatched grid of lines within the second shape corresponding to features formed in a number of levels of exposure; and forming rotationally symmetric shapes at intersections of the cross-hatched grid of lines. Still another aspect includes the first shape being a square and the second shape being a quadrilateral. 
         [0013]    Additional aspects and technical effects of the present disclosure will become readily apparent to those skilled in the art from the following detailed description wherein embodiments of the present disclosure are described simply by way of illustration of the best mode contemplated to carry out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
           [0015]      FIGS. 1 and 2  schematically illustrate a method for forming an alignment mark, in accordance with an exemplary embodiment; 
           [0016]      FIGS. 3A and 3B  schematically illustrate additional alignment marks that may be formed based on the method illustrated in  FIGS. 1 and 2 , in accordance with exemplary embodiments; 
           [0017]      FIGS. 3C and 3D  schematically illustrate alignment mark placement in four corners of a reticle field before and after a 90 degree rotation, in accordance with an exemplary embodiment; 
           [0018]      FIGS. 3E ,  3 G and  3 I illustrate a wafer level including alignment marks, in accordance with exemplary embodiments; 
           [0019]      FIGS. 3F and 3H  illustrate alignment mark placement in corners of a reticle field, in accordance with exemplary embodiments; 
           [0020]      FIGS. 4A through 5L  illustrate a method for forming a first shape of an alignment mark, in accordance with an exemplary embodiment; and 
           [0021]      FIGS. 6A through 7I  illustrate a method for forming a first shape of an alignment mark, in accordance with an alternative exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of exemplary embodiments. It should be apparent, however, that exemplary embodiments may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring exemplary embodiments. In addition, unless otherwise indicated, all numbers expressing quantities, ratios, and numerical properties of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” 
         [0023]    The present disclosure addresses and solves the current problem of limited functionality and specificity attendant upon alignment marks. In accordance with embodiments of the present disclosure, a general alignment mark is described for use in OGA, SEMGA, in addition to overlay measurements and reticle inspection alignment. 
         [0024]    Methodology in accordance with an embodiment of the present disclosure includes forming a first shape having rotational symmetry. The first shape may be a square. A second shape is then formed, one or more of which are combined with the first shape to form an alignment mark with rotational symmetry. The first shape may further include rotationally symmetric shapes along one or more concentric outlines corresponding to features formed in a number of levels of exposure. The second shape may further include a cross-hatched grid of lines corresponding to features formed in the number of levels of exposure. 
         [0025]    Adverting to  FIG. 1 , a method for forming an alignment mark, according to an exemplary embodiment, begins with forming a first shape  101 . The first shape  101  has rotational symmetry, such as by being 90-degree rotationally symmetric. Thus, although the first shape  101  is illustrated as a square, the first shape  101  can be any shape that is at least 90-degree rotationally symmetric, such as a circle, an octagon, a plus sign with equal length sides, etc. 
         [0026]    Adverting to  FIG. 2 , one or more of a second shape  201  are formed and combined with the first shape  101 . As illustrated, four of the second shape  201  can be combined with the first shape  101 . The second shape  201  is combined with the first shape  101  so that edges of the second shapes  201  are contiguous with separate edges of the first shape  101 . Thus, as illustrated in  FIG. 2 , four of the second shape  201  are combined with the first shape  101  such that each second shape  201  is contiguous with a separate edge of the first shape  101 . Further, the first shape  101  and the one or more of the second shape  201  are combined so that the resulting alignment mark  203  is rotationally symmetric, such as at least 90-degree rotationally symmetric. Although the alignment mark  203  is illustrated as including four of the second shape  201 , one for each edge of the first shape  101 , the number of second shapes  201  may be less than the number of edges of the first shape  101  as long as the resulting alignment mark is at least 90-degree rotationally symmetric. For example, a first shape in the form of an octagon may include only four of the second shape, one on every other edge, rather than eight (e.g., one for each side). 
         [0027]    As illustrated in  FIGS. 3A and 3B , the second shape can be various shapes, which do not need to be rotationally symmetric. Alignment mark  301  includes the first shape  101  and four of a second shape  303  in the form of a square. Alignment mark  305  includes the first shape  101  and four of a second shape  307  in the form of a rectangle. Although not shown (for illustrative convenience), the second shape can be other shapes, such as a triangle, a circle, a quadrilateral, etc., as long as the resulting alignment mark is at least 90-degree rotationally symmetric. 
         [0028]      FIGS. 3C and 3D  illustrate alignment marks  203   a - 203   d  in the four corners of a reticle field  309  before ( FIG. 3C ) and after ( FIG. 3D ) a 90-degree reticle inspection alignment. According to some layouts, the reticle field  309  may also include four frame or corner marks  311 . Although the reticle field  309  is rotated 90 degrees clockwise from  FIG. 3C  to  FIG. 3D , the alignment marks  203   a - 203   d  appear the same despite also having been rotated 90 degrees to the right, although the alignment marks  203   a - 203   d  remain in the same spots relative to before inspection. The alignment marks  203   a - 203   d  appear the same because the marks are rotationally symmetric at least about a 90-degree rotation. The optical alignment can, therefore, be the same for any n times of a 90-degree rotation.  FIG. 3E  illustrates a wafer level  313  that includes alignment marks  203   e - 203   h  (although not to scale) and corner marks  311  at corners of four reticle fields  309   a - 309   d.  Alignment marks  203   e - 203   h  as such allow for global optical setup for critical dimension scanning electronic microscope (CD-SEM) job files and metrology job files.  FIG. 3F  illustrates an alternative reticle field  315  with alignment marks  203   a - 203   d  where the reticle field  315  may not include corner marks illustrated in  FIGS. 3C and 3D . Similarly,  FIG. 3G  illustrates a wafer level  317  that includes alignment marks  203   e - 203   h  (although not to scale) without corner marks at corners of four reticle fields  315   a - 315   d.  Thus, including the corner marks  311  may not be necessary based on different layouts.  FIG. 3H  illustrates the reticle field  319  including only two alignment marks  203   a  and  203   c  at the top left and bottom right corners. However, the two alignment marks  203   a  and  203   c  may alternatively be at the top right and bottom left corners (e.g., opposite corners).  FIG. 3I  illustrates a wafer level  321  including two reticle fields  319   a  and  319   b  having only two alignment marks  203   a  and  203   c.  The reticle field  319  and wafer level  321  may be for a different layout having 100% exposure for different reticle overlapping. 
         [0029]    For 20 nm and below technology nodes, there are two or more layers of poly and active layers. Further, contact, vertical interconnect access (VIA) and metal layers may use double or triple patterning. Thus, it is important to monitor the overlay of the double patterning. Further, because both size and overlay of implant layers is important for 28 nm nodes and below, it is also important to monitor the overlay for implant layers. Thus,  FIGS. 4A through 5K  illustrate forming additional detail in the alignment marks discussed above that can be used for forming front-end-of-line (FEOL) and/or middle-of-line (MOL) features in semiconductor devices, using alignment mark  301  as an example. However, the discussion below can be applied to other alignment marks discussed above. 
         [0030]    Adverting to  FIG. 4A , the first shape  101  may include additional detail. For example, the first shape  101  may include one or more concentric circles. As illustrated, the first shape  101  includes three concentric circles  401   a - 401   c.  Although only three concentric circles are illustrated, the first shape  101  may include additional concentric circles that may correspond to additional exposure layouts (e.g., triple exposure layout, etc.). 
         [0031]    Next, implant layer marks  403  are added to the first shape  101 , as illustrated in  FIG. 4B . The implant layer marks  403  correspond to a step for forming an implant layer. Although the implant layer marks  403  are illustrated as plus signs, the implant layer marks  403  may be any shape. Alternatively, the implant layer marks  403  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the implant layer marks  403  are not fixed such that the implant layer marks  403  may be at any location within the first shape  101  along one or more of the concentric circles  401   a - 401   c.  Alternatively, the implant layer marks  403  may be located within the first shape  101  along one or more of the concentric circles  401   a - 401   c  such that the first shape  101 , including the implant layer marks  403 , is 90-degree rotationally symmetric. 
         [0032]    Subsequently, first active layer marks  405  are added to the first shape  101 , as illustrated in  FIG. 4C . The first active layer marks  405  correspond to a step for forming a first active layer. Although the first active layer marks  405  are illustrated as plus signs of various sizes, the first active layer marks  405  may be any shape and/or size. Alternatively, the first active layer marks  405  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the first active layer marks  405  are not fixed such that the first active layer marks  405  may be at any location within the first shape  101  along one or more of the concentric circles  401   a - 401   c.    
         [0033]    Next, second active layer marks  407  are added to the first shape  101 , as illustrated in  FIG. 4D . The second active layer marks  407  correspond to a step for forming a second active layer. Although the second active layer marks  407  are illustrated as plus signs, the second active layer marks  407  may be any shape and/or size. Alternatively, the second active layer marks  407  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the second active layer marks  407  are not fixed such that the second active layer marks  407  may be at any location within the first shape  101  along one or more of the concentric circles  401   a - 401   c.    
         [0034]    Poly layer marks  409  are then added to the first shape  101 , as illustrated in  FIG. 4E . The poly layer marks  409  correspond to a step for forming a poly layer. Although the poly layer marks  409  are illustrated as plus signs, the poly layer marks  409  may be any shape. Alternatively, the poly layer marks  409  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the poly layer marks  409  are not fixed such that the poly layer marks  409  may be at any location within the first shape  101  along one or more of the concentric circles  401   a - 401   c.    
         [0035]    Next, cut layer marks  411  are added to the first shape  101 , as illustrated in  FIG. 4F . The cut layer marks  411  correspond to a step for a cut layer. Although the cut layer marks  411  are illustrated as plus signs, the cut layer marks  411  may be any shape. Alternatively, the cut layer marks  411  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the cut layer marks  411  are not fixed such that the cut layer marks  411  may be at any location within the first shape  101  along one or more of the concentric circles  401   a - 401   c.    
         [0036]    Then, first contact layer marks  413  are added to the first shape  101 , as illustrated in  FIG. 4G . The first contact layer marks  413  correspond to a step for a first contact layer. Although the first contact layer marks  413  are illustrated as squares, the first contact layer marks  413  may be any shape. Alternatively, the first contact layer marks  413  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the first contact layer marks  413  are not fixed such that the first contact layer marks  413  may be at any location within the first shape  101  along one or more of the concentric circles  401   a - 401   c.    
         [0037]    Finally, second contact layer marks  415  are added to the first shape  101 , as illustrated in  FIG. 4H . The contact layer marks  415  correspond to a step for a second contact layer. Although the contact layer marks  415  are illustrated as squares, the second contact layer marks  415  may be any shape. Alternatively, the contact layer marks  415  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the second contact layer marks  415  are not fixed such that the second contact layer marks  415  may be at any location within the first shape  101  along one or more of the concentric circles  401   a - 401   c.  The result is a first shape  101  in an alignment mark  301  that can be used for alignment while forming FEOL features of semiconductors devices. 
         [0038]    Adverting to  FIG. 5A , the second shape  303  may also include additional detail for specific steps within FEOL and/or MOL process flows. For example, the second shape  301  may include a hashed pattern that is made up of lines and/or circles representing steps in FEOL process flow. The hashed pattern may be formed according to the following. 
         [0039]    Vertical lines  501  are added to the second shape  303 , as illustrated in  FIG. 5A . The vertical lines  501  correspond to the formation of a first active layer. Although there are three vertical lines  501 , at the left edge, center and right edge of the second shape  303 , the number, size and location of the vertical lines  501  may vary. 
         [0040]    Next, vertical lines  503  are added to the second shape  303 , as illustrated in  FIG. 5B . The vertical lines  503  correspond to the formation of a second active layer. Although there are two vertical lines  503  at the left center and right center of the second shape  303 , the number, size and location of the vertical lines  503  may vary. Alternatively, as illustrated in  FIG. 5C , the second shape  303  may instead include five vertical lines  501  that correspond to the formation of the first active layer and a poly layer, rather than the vertical lines  501  and vertical lines  503  corresponding to the first and second active layers, respectively. 
         [0041]    After forming the vertical lines  503 , horizontal lines  505  are then added to the second shape  303 , as illustrated in  FIG. 5D . The horizontal lines  505  correspond to the formation of a poly layer. Although there are three horizontal lines  505 , at the top, center and bottom of the second shape  303 , the number, size and location of the horizontal lines  505  may vary. 
         [0042]    Subsequently, horizontal lines  507  are added to the second shape  303 , as illustrated in  FIG. 5E . The horizontal lines  507  correspond to the formation of a cut layer. Although there are two horizontal lines  507 , at the middle top and middle bottom of the second shape  303 , the number, size and location of the horizontal lines  507  may vary. Alternatively, as illustrated in  FIG. 5F , the second shape may instead include five horizontal lines  505  that correspond to the formation of the second active layer and a poly cut layer, rather than the horizontal lines  505  and horizontal lines  507  corresponding to the poly layer and the cut layer, respectively. 
         [0043]    Moreover, as illustrated in  FIG. 5G , the second shape  303  may include overlapping vertical and horizontal layers, such as layer  303   a  that overlaps above layer  303   b  of the second shape  303 . Layer  303   b  may include vertical lines  501  corresponding to the formation of a first active layer and horizontal lines  503  corresponding to the formation of a second active layer. Further, layer  303   a  above layer  303   b  may include vertical lines  505  corresponding to the formation of a poly layer and horizontal lines  507  corresponding to the formation of a poly cut layer. Thus, vertical lines  505  overlap vertical lines  501 , and horizontal lines  507  overlap horizontal lines  503 . Of course, the number, size and location of the vertical lines  501  and  505  and the horizontal line  503  and  507  may vary. 
         [0044]    After forming the horizontal lines  507 , circles  509  are added to the second shape  303 , as illustrated in  FIG. 5H . The circles  509  correspond to the formation of a first contact layer. The circles  509  may be formed at intersections of the vertical lines  501  and the horizontal lines  505 , as well as at the intersections of the vertical lines  503  and the horizontal lines  507 . However, the number, size, shape and location of the circles  509  may vary. 
         [0045]    Circles  511  are also added to the second shape  303 , as illustrated in  FIG. 5I . The circles  511  correspond to the formation of a second contact layer. The circles  511  may be formed at intersections of the vertical lines  503  and the horizontal lines  505 , as well as at the intersections of the vertical lines  501  and the horizontal lines  507 . However, the number, size, shape and location of the circles  511  may vary. 
         [0046]      FIGS. 5J and 5K  illustrate that the circles  509  and  511  may be formed to include features  513  that correspond to contacts formed in the semiconductor devices. Although nine features  513  are illustrated in a 3×3 pattern, the number and shape of the features  513  may vary, such as the circles  509  and  511  including only one feature (e.g., 1×1) or more than nine features (e.g., 5×5). As the number of features  513  included within the circles  509  and  511  increases, the size of the features  513  decreases. Further, the number of features  513  within the circles  509  and  511  may correspond to a size of the contacts such that a larger number of features  513  corresponds to smaller contacts. 
         [0047]    The result is a second shape  303  in an alignment mark  301  that can be used for alignment while forming FEOL and/or MOL features of semiconductor devices. Further, the result is a second shape  303  that is not rotationally symmetric, as illustrated in  FIG. 5L , which shows a 90-degree clockwise rotated version of the second shape  303  in  FIG. 5I . 
         [0048]      FIGS. 6A through 7I  illustrate forming details in a first shape  603  and a second shape  605  for an alignment mark  601  for back-end-of-line (BEOL) features, such as forming the horizontal and vertical metal line overlap areas. Adverting to  FIG. 6A , the first shape  603  may include additional detail. For example, the first shape  603  may include one or more concentric circles. As illustrated, the first shape  603  includes three concentric circles  607   a - 607   c.  Although only three concentric circles are illustrated, the first shape  603  may include additional concentric circles that correspond to additional exposure layouts (e.g., triple exposure layout). 
         [0049]    Next, first metal layer marks  609  are added to the first shape  603 , as illustrated in  FIG. 6B . The first metal layer marks  609  correspond to a step for forming a first metal layer. Although the first metal layer marks  609  are illustrated as plus signs of various sizes, the first metal layer marks  609  may be any shape. Alternatively, the first metal layer marks  609  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the first metal layer marks  609  are not fixed such that the first metal layer marks  609  may be at any location within the first shape  603  along one or more of the concentric circles  607   a - 607   c . Alternatively, the first metal layer marks  609  may be located within the first shape  603  along one or more of the concentric circles  607   a - 607   c  such that the first shape  603 , including the first metal layer marks  609 , is 90-degree rotationally symmetric. 
         [0050]    Second metal layer marks  611  are next added to the first shape  603 , as illustrated in  FIG. 6C . The second metal layer marks  611  correspond to a step for forming a second metal layer. Although the second metal layer marks  611  are illustrated as plus signs, the second metal layer marks  611  may be any shape. Alternatively, the second metal layer marks  611  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the second metal layer marks  611  are not fixed such that the second metal layer marks  611  may be at any location within the first shape  603  along one or more of the concentric circles  607   a - 607   c.    
         [0051]    Then, first VIA marks  613  are added to the first shape  603 , as illustrated in  FIG. 6D . The first VIA marks  613  correspond to a step for forming first VIAs. Although the first VIA marks  613  are illustrated as squares, the first VIA marks  613  may be any shape. Alternatively, the first VIA marks  613  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the first VIA marks  613  are not fixed such that the first VIA marks  613  may be at any location within the first shape  603  along one or more of the concentric circles  607   a - 607   c.  Although the first VIA marks  613  are illustrated in a pattern that is not 90-degree rotationally symmetric, the pattern of the first VIA marks  613  may alternatively be 90-degree rotationally symmetric. 
         [0052]    Subsequently, second VIA marks  615  are added to the first shape  603 , as illustrated in  FIG. 6E . The second VIA marks  615  correspond to a step for forming second VIAs. Although the second VIA marks  615  are illustrated as squares, the second VIA marks  615  may be any shape. Alternatively, the second VIA marks  615  may be any shape that is 90-degree rotationally symmetric. Further, the specific locations of the second VIA marks  615  are not fixed such that the second VIA marks  615  may be at any location within the first shape  603  along one or more of the concentric circles  607   a - 607   c.  Although the second VIA marks  615  are illustrated in a pattern that is not 90-degree rotationally symmetric, the pattern of the second VIA marks  615  may alternatively be 90-degree rotationally symmetric. The result is a first shape  603  in an alignment mark  601  that can be used for alignment while forming BEOL features of semiconductors devices. 
         [0053]    Adverting to  FIG. 7A , the second shape  605  may also include additional detail for specific steps within a BEOL process flow. Vertical lines  701  are added to the second shape  605 , as illustrated in  FIG. 7A . The vertical lines  701  correspond to the formation of a first part of a metal 1 (e.g., M1) layer. Although there are three vertical lines  701 , at the left edge, center and right edge of the second shape  605 , the number, size and location of the vertical lines  701  may vary. 
         [0054]    Vertical lines  703  are then added to the second shape  605 , as illustrated in  FIG. 7B . The vertical lines  703  correspond to the formation of a second part of the M1 layer. Although there are two vertical lines  703  at the left center and right center of the second shape  605 , the number, size and location of the vertical lines  703  may vary. Vertical lines  701  and  703  may be used to form an M1 layer using double patterning. If the M1 layer is formed using triple patterning or above, the second shape  605  may include additional sets of vertical lines corresponding to a number of patterning steps, such as an additional set of vertical lines in combination with vertical lines  701  and  703  for triple patterning. 
         [0055]    Next, horizontal lines  705  are added to the second shape  605 , as illustrated in  FIG. 7C . The horizontal lines  705  correspond to the formation of a first part of a metal 2 (e.g., M2) layer. Although there are three horizontal lines  705 , at the top, center and bottom of the second shape  605 , the number, size and location of the horizontal lines  705  may vary. 
         [0056]    Horizontal lines  707  are then added to the second shape  605 , as illustrated in  FIG. 7D . The horizontal lines  707  correspond to the formation of a second part of the M2 layer. Although there are two horizontal lines  707 , at the middle top and middle bottom of the second shape  605 , the number, size and location of the horizontal lines  707  may vary. Similar to the vertical lines, horizontal lines  705  and  707  may be used to form an M2 layer using double patterning. If the M2 layer is formed using triple patterning or above, the second shape  605  may include additional sets of horizontal lines corresponding to a number of patterning steps, such as an additional set of horizontal lines in combination with horizontal lines  705  and  707  for triple patterning. 
         [0057]    Circles  709  are then added to the second shape  605 , as illustrated in  FIG. 7E . The circles  709  correspond to the formation of a first part of a VIA layer. The circles  709  may be formed at intersections of the vertical lines  701  and the horizontal lines  705 , as well as at the intersections of the vertical lines  703  and the horizontal lines  707 . However, the number, size, shape, and location of the circles  709  may vary. 
         [0058]    Next, circles  711  are added to the second shape  605 , as illustrated in  FIG. 7F . The circles  711  correspond to the formation of a second part of a VIA layer. The circles  711  may be formed at intersections of the vertical lines  703  and the horizontal lines  705 , as well as at the intersections of the vertical lines  701  and the horizontal lines  707 . However, the number, size, shape and location of the circles  711  may vary. 
         [0059]      FIGS. 7G and 7H  illustrate that the circles  709  and  711  may be formed to include features  713  that correspond to VIAs formed in the semiconductor devices. Although nine features  713  are illustrated in a 3×3 pattern, the number and shape of the features  713  may vary, such as the circles  709  and  711  including only one feature (e.g., 1×1) or more than nine features (e.g., 5×5). As the number of features  713  included within the circles  709  and  711  increases, the size of the features  713  decreases. Further, the number of features  713  within the circles  709  and  711  may correspond to a size of the VIAs such that a larger number of features  713  corresponds to smaller VIAs. 
         [0060]    The result is a second shape  605  in an alignment mark  603  that can be used for alignment while forming BEOL features of semiconductors devices. Further, the result is a second shape  605  that is not rotationally symmetric, as illustrated in  FIG. 71 , which shows a rotated version of the second shape  605  in  FIG. 7F . Providing the alignment marks  301  and/or  601  uniformly distributed in the four corners of a reticle provide the overlay information for both the reticle and wafer. 
         [0061]    The embodiments of the present disclosure achieve several technical effects, including providing general scanning electron microscope and optical alignment marks for single, double, and triple exposures, and beyond, providing an optical alignment mark for reticle inspection alignment, and providing overlay measurements. The present disclosure enjoys industrial applicability associated with the designing and manufacturing of any of various types of highly integrated semiconductor devices used in microprocessors, smart phones, mobile phones, cellular handsets, set-top boxes, DVD recorders and players, automotive navigation, printers and peripherals, networking and telecom equipment, gaming systems, and digital cameras. Thus, the present disclosure is applicable to any of various highly integrated semiconductor devices, particularly for the 28 nm technology node and beyond. 
         [0062]    In the preceding description, the present disclosure is described with reference to specifically exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present disclosure, as set forth in the claims. The specification and drawings are, accordingly, to be regarded as illustrative and not as restrictive. It is understood that the present disclosure is capable of using various other combinations and embodiments and is capable of any changes or modifications within the scope of the inventive concept as expressed herein.