Abstract:
The present invention relates to metallization line layouts that minimize focus offset sensitivity by a substantial elimination of thin isolated metallization line segments that are inadequately patterned during formation of a mask. The present invention also relates to a metallization line layout that staggers unavoidable exposures. Embodiments of these metallization line layouts include enhanced terminal ends of isolated metallization lines, filled inter-metallization line spaces, and additional “dummy” metal shapes in open areas. The present invention also relates to a method of forming a metallization layer such that a substantially deposited, planarized interlayer dielectric layer can be formed without etchback or chemical-mechanical polishing.

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/388,894, filed on Sep. 2, 1999 now U.S. Pat. No. 6,448,591, which is a continuation-in-part of U.S. patent application Ser. No. 08/514,988, filed on Aug. 14, 1995, now U.S. Pat. No. 5,981,384, and a continuation- in-part of U.S. patent application Ser. No. 08/971,869, filed on Nov. 19, 1997, now U.S. Pat. No. 5,965,940, which is a divisional of U.S. patent application Ser. No. 08/514,988, filed on Aug. 14, 1995, now U.S. Pat. No. 5,981,384, all of which being incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to the fabrication of microelectronic semiconductor devices. More particularly, the present invention relates to the fabrication of metallization lines. In particular, the present invention relates to a metallization line layout optimization to avoid depth of field sensitivity and excess reflectance in isolated metallization lines. Additionally, the present invention achieves a substantially planar dielectric layer upper surface, upon deposition and without further processing, of the dielectric layer over the inventive metallization line layout. 
     2. The Relevant Technology 
     In the microelectronics industry, a substrate refers to one or more semiconductor layers or structures which includes active or operable portions of semiconductor devices. In the context of this document, the term “semiconductive substrate” is defined to mean any construction comprising semiconductive material, including but not limited to bulk semiconductive material such as a semiconductive wafer, either alone or in assemblies comprising other materials thereon, and semiconductive material layers, either alone or in assemblies comprising other materials. The term “substrate” refers to any supporting structure including but not limited to the semiconductive substrates described above. 
     Following the formation of semiconductor devices, the devices need to be electrically connected, either to themselves or to the outside world to make the semiconductor device function as part of a greater whole. The electrical connection of the semiconductor devices is carried out by the metallization process. Metallization comprises the layout and patterning of a series of electrically conductive lines upon an upper surface of a substrate. The metallization lines make electrical connection, through either vias or interconnects, between individual semiconductor devices and/or the outside world. 
     FIG. 1 illustrates a plan view of a typical “Manhattan” style metallization line layout  10 , by way of non-limiting example, at least a portion of a metal- 1  layout for a sense amplifier. A Manhattan style metallization layout may also be called a rectangular, or right-angle rectilinear metallization layout. Such a metallization layout is characterized by raised, elongate structures that have only substantially right-angle deviations from being straight or linear. The term “vertical” is intended to mean a direction between the top and bottom of the page of a figure. The term “lateral” is intended to means a sideways direction of a figure, substantially orthogonal to “vertical.” 
     Referring to FIG. 1, arbitrary region Z is seen in FIG. 1 to have a substantially rectangular shape that includes parallel vertical boundaries  15 ,  15 ′ and parallel horizontal boundaries  17 ,  17 ′. Metallization lines include isolated lines and may be shown as having an end  11  within an arbitrary region Z. Metallization lines include continuous lines and are shown as extending substantially across FIG. 1 with no end found within arbitrary region Z. For example, isolated line  1 -left (isolated line  1 L) is defined as having end  11  within arbitrary region Z of metallization line layout  10 , and arbitrary region Z does not include a physical edge of metallization line layout  10 . An “end”  11  is defined as a portion of a metallization line that discontinues within arbitrary region Z and that has a length that may be substantially the width W of the metallization line for a length along the same metallization line at least equal to the distance W. 
     It is noted that in the prior art “Manhattan” layout of metallization line layout  10 , ends  11  for all of isolated lines  1 R- 11 R are all a fixed distance  27  from a closest vertical boundary  15  of arbitrary region Z, or a fixed distance  29  from a closest boundary  15 ′. 
     A continuous line is defined as having no end within arbitrary region Z of metallization line layout  10 . For example, continuous line  3  has no end within arbitrary region Z depicted as FIG.  1 . Continuous line  3  has an enlarged feature  13 . 
     FIG. 1 illustrates several occurrences of isolated lines and continuous lines. As used herein, an “intersection” is defined as a subregion within arbitrary region Z at which at least one end of a metallization line occurs. The four top-most metallization lines in FIG. 1 are demarcated as isolated lines  1 L and  2 L and isolated lines  1 R and  2 R. The next metallization line down is a continuous metallization line and is thus demarcated as continuous line  3 . 
     An intersection is defined as a portion of a layout with at least one end  11 . The intersection may be bordered by a continuous line. For example, a 6-way intersection occurs at the demarcation X where it can be seen that a 6-arrowed illustrative figure has been drawn to demonstrate the 6-way nature of this intersection. Intersection X is bordered by continuous lines  6  and  9 . Intersection X includes the spaces between continuous line  6 , isolated line  7 L, isolated line  8 L, isolated line  7 R, isolated line  8 R, and continuous line  9 . 
     A 4-way intersection may be considered as occurring at the demarcation Y where it can be seen that a 4-arrowed illustrative figure has been drawn. The 4-way intersection is thus defined as an open region having ends  11 , that has a clear line of sight, for example between isolated lines  10 L and  11 L, between isolated lines  10 L and  10 R, between isolated lines  10 R and  11 R, and between isolated lines  11 R and  11 L. A 3-way intersection maybe considered as occurring in FIG. 1A at the demarcation V where it can be seen that a 3-arrowed illustrative figure has been drawn near end  11 . This intersection is thus created by an open region that has a clear line of sight between isolated line  2 L and continuous line  1 , between continuous line  1  and continuous line  3 , and between continuous line  3  and isolated line  2 L. Thus, by this definition, an intersection represents the space between a plurality of metallization lines, wherein at least one metallization line has an end that creates at least a portion of the space therebetween. 
     The metallization lines have been fabricated in the past at a minimum width and as far apart as possible in order to avoid the problems of capacitative coupling and shorting. While the advantages of avoiding capacitative coupling and shorting are preferred, the ever-increasing pressure to miniaturize microelectronic devices influences the design engineer to decrease the overall scale of a metallization line layout. This decrease gives rise to at least three significant problems for the process engineer. 
     The first significant problem is the focus offset sensitivity or depth of field capability of existing photolithographic exposure equipment. The equipment&#39;s focus offset sensitivity may cause significant problems during patterning of isolated metallization lines. As photolithographic exposure wavelengths become less optimal due to the ever-decreasing scale of the layout, focus offset sensitivity will blur the edges of the metallization line mask. Thereby the entire exposure of the metallization line mask may be excessively blurred, the mask may fail to form, and no metallization line may result. Excessive blurring can cause the problem of an open circuit. This problem may be overcome by widening metallization lines, but widening can be detrimentally offset by the likelihood of short circuiting across metallization lines because nearby closest features may bridge and short or contaminant particles may bridge between metallization lines and create a short circuit. 
     The second significant problem occurs during fabrication of the metallization lines due to undesired exposure to the masking material and the excess reflectance problems caused by photolithographic light. Light exposure with excess reflectance results in the lateral thinning and/or the recession of a metallization line end of the masking material. Hence, either a thinned, receded, or discontinuous metallization line feature results. Although such excess reflectance may only thin the metallization line feature, thinning thereof will leave the metallization line feature vulnerable to electromigration failure. 
     In FIG. 1, it can be demonstrated that the excess reflectance problem does not usually occur where any given metallization line such as continuous line  3  has a nearby closest feature  16  such as the proximal edge of isolated line  2 L relative to point A upon an edge of continuous line  3 . Nearby closest feature  16  an edge of isolated line containing point A is at the distance of α 0  from point A. 
     The problem of an excess reflectance may occur for metallization lines where the closest feature is at a distance greater than α 0 . For example, the exposed point C is located upon the same edge of continuous line  3  as point A. Point C is at a lateral-component distance from a nearest neighboring feature that is about evenly spaced between isolated lines  2 L and  2 R ends  11 . Point C has at least one distant closest feature  24  at a distance γ 0 , that is greater than distance α 0 . At point C above, and at point C′ below on continuous line  3 , it can be seen that continuous line  3  has respective open exposures,  20  and  21 , due to the break in metallization lines that form the intersection between ends  11  of isolated lines  2 L and  2 R and between isolated lines  4 L and  4 R. Open exposures  20 ,  21 , can cause excess reflectance at respective points C and C′. 
     Excess reflectance can also occur at other structures. In FIG. 1, it can be seen that isolated lines  2 L and  4 L, when scanned from left to right, each have a first right-angle direction change. For  2 L it is downwardly vertical, and for  4 L it is upwardly vertical. Each of these direction changes is followed by a second right-angle direction change that restores lines  2 L and  4 L to run parallel to continuous line  3 . Upon continuous line  3  at the point B above, and the point B′ below, it can be seen that the nearest features thereto are the distant closest features  24  and  25  that each have a diagonal distance of β 0  between respective points B and B′ and distant closest features  24  and  25 . It can be seen that points B and B′ upon continuous line  3  also have excess space around them compared to point A. These excess spaces are respective enclosed exposures  18  and  19  of continuous line  3 . These exposures are referred to as enclosed exposures because points B and B′ ultimately have regional metallization line features both above and below, caused in this example by the occurrence of isolated lines  2 L and  4 L. Enclosed exposures  18  and  19  are likewise detrimental to patterning of the metallization lines similar to open exposures  20  and  21 . 
     Other exposures to occurrences of isolated lines such as isolated lines  5 L and  5 R include the respective terminal end exposures  22  and  23 . Here it can be seen that excess light exposure occurs during photolithographic layout due to the lack of any nearby closest feature  16  such as seen for continuous line  3  at point A. 
     Because of excess reflectance problems caused by light exposure near such spaces as enclosed exposures  18  and  19 , open exposures  20  and  21 , and terminal end exposures  22  and  23 , there will result an ultimate lateral thinning and/or the recession of an end of the masking material, and either a thinned, receded, or discontinuous metallization line feature for a continuous metallization line. Even though such exposure may not cause a breach in the metallization line feature during fabrication, the thinning of the metallization line will leave the metal line vulnerable to electromigration failure. 
     The third significant problem caused by miniaturization is an enhanced possibility of an interstitial particulate occurrence or a fabrication error that will cause a bridge to form between adjacent metallization lines, thereby shorting out an associated device and causing the device to fail. The semiconductive device design and process engineer must thus balance the advantage of miniaturization against the disadvantage of causing shorting due to impurity bridging or fabrication imperfection bridging. 
     What is needed in the art is a metallization design and associated method of fabrication that avoids the problems of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a metallization line layout and fabrication thereof that avoids the creation of metallization line thinning and/or disappearance for excess reflectance-vulnerable metallization line features therein. The present invention accomplishes this objective by taking an existing metallization line layout that has been dictated by the fabrication of a semiconductor device array and by eliminating distant closest features that would otherwise cause the aforementioned problems that existed in the prior art. The method of eliminating distant closest features includes enhancing terminal ends of isolated metallization lines. The method of eliminating distant closest features also includes thickening metallization line widths to achieve substantially only nearby closest features. The method of eliminating distant closest features likewise includes filling spaces between metallization line features to achieve a substantially standard preferred distance between any given metallization line feature and its nearest closest metallization line feature. Additionally, the method of eliminating distant closest features includes staggered unavoidable exposures, after a fashion that causes any given metallization line feature that must have an exposure, to only have a single occurrence thereof on one side of the metallization line. The present invention also includes placing additional “dummy” metal shapes in open areas to create a nearby closest feature where the original layout did not provide for such a feature. 
     The metallization lines may include metals, alloys, and the like. The metallization lines may include doped polysilicon and the like. The metallization lines may include refractory metal nitrides, and the like. The metallization lines may also include superconductive ceramics and the like. 
     The present invention is carried out by providing a metallization line layout and determining the existence of a space between any point on a metallization line and the nearest feature on the closest neighboring metallization line. Further, a measurement of each such space is taken between the selected point and the nearest feature on the closest neighboring metallization line. Thereafter, it is determined whether the selected point on the metallization line is at a distance from the feature that is greater than a predetermined preferred distance. Where the distance is greater than the predetermined preferred distance, either the metallization line itself, the closest feature, or both are enhanced in size, preferably incrementally and globally, in a direction approaching the preferred distance. Following enhancement, a measurement of the space as enhanced is again taken between the point and its nearest feature. The process is repeated until substantially no nearest feature upon any metallization line is at a distance significantly different from the preferred distance. Additionally, the method assures that any exposure on one side of a metallization line is not coupled with an exposure on the exact opposite side of the metallization line, within a preferred minimal distance. In this way, excess exposure to a metallization line is limited to one side in the area of the exposure. 
     These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the manner in which the above-recited and other advantages of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is a typical prior art metal- 1  layout of a sense amplifier. The metallization lines are configured at a minimum width and as far apart from each other as possible to avoid capacitative coupling and/or shorting due to defective metallization line fabrication; 
     FIG. 1A illustrates a 3-way intersection of the prior art with uneven spacing between metallization lines and exposed and vulnerable terminal and lateral features. 
     FIG. 2 shows the inventive metallization line layout superimposed on a portion of the metal- 1  layout depicted in FIG. 1; 
     FIG. 3 shows the inventive metallization line layout of one embodiment of the present invention, wherein it can be seen that no standard 6-way intersection that separates metallization lines occurs upon the improved metallization line layout, and wherein it is illustrated that substantially standard spacing has been achieved throughout the entire improved metallization line layout; 
     FIG. 4 is a detail section taken from FIG. 3 along the arbitrary rectangular boundary  4 — 4 ; 
     FIG. 5 is a detail section taken from FIG. 3 along the arbitrary rectangular boundary  5 — 5 ; 
     FIG. 6 shows the inventive metallization line layout as it appears in a preferred embodiment where a prior art 3-way intersection, consisting of two continuous lines and one interposed isolated line, has been enhanced; 
     FIGS. 7A,  7 B, and  7 C illustrate three cross-sectional views of an improved metallization line layout wherein it can be seen that a planar upper surface is the result of ILD formation upon the inventive structure, without further processing required; and 
     FIG. 8 is a plan view of an alternative embodiment of the present invention wherein non 90-degree metallization line direction changes occur about a symmetry line, and wherein the inventive process is applied in this region. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings wherein like structures will be provided with like reference designations. It is to be understood that the drawings are diagrammatic and schematic representations of the embodiment of the present invention and are not drawn to scale. 
     FIG. 2 illustrates an enlargement of the designing and preparation of metallization line layout  10 , seen in FIG. 1, to form a metallization line layout  110  according to the present invention. In FIG. 2, it can be seen that isolated lines and continuous lines have been enhanced by additional material during the design process. Enhancements may comprise a simple vertical upward- or downward-directed enhancement, a combination of vertical and lateral enhancements, a simple lateral enhancement, or a corner enhancement. For example, line  101 L has been enhanced by a line  1 L vertical enhancement  32 . Line  101 R has been enhanced by both a line  1 R vertical/lateral enhancement  34  and a line  1 R vertical enhancement  36 . Line  102 L has been enhanced by a line  2 L vertical enhancement  40  and a line  2 L vertical/lateral enhancement  38 . Line  102 R has been enhanced by a line  2 R vertical enhancement  41 . Line  103  has been enhanced by a line  3  vertical/lateral enhancement  42  and by a line  3  vertical enhancement  44 . Line  104 L has been enhanced by a line  4 L vertical/lateral enhancement  48  and a line  4 L vertical enhancement  50 . Additionally it can be seen that line  104 L has been enhanced by a line  4 L corner enhancement  46  as have several other lines. Line  104 R has been enhanced by a line  4 R vertical/lateral enhancement  52 . Line  105 L has been enhanced by a line  5 L vertical enhancement  54  and by a line  5 L vertical/lateral enhancement  56 . Line  105 R has been enhanced by a line  5 R vertical enhancement  58  and a line  5 R vertical/lateral enhancement  60 . Other lines in FIG. 2 have been enhanced as characterized above. 
     Point A as depicted in FIG. 1 is represented in FIG. 2 as point AA. Point AA demonstrates that point A has moved vertically away from enhanced line  103  because of the vertical enhancement portion of line  3  vertical/lateral enhancement  42 . The distance between enhanced line  102 L and enhanced line  103  is represented as α 1 , a lesser distance than α 0 , seen in FIG.  1 . Distance α 1 , represents a preferred distance that occurs between enhanced line  102 L at nearby closest feature  16  and enhanced line  103  at point AA. In each case as set forth herein, the distance α 1  is understood to be measured in a direction that departs from a first line, e.g., enhanced line  103  at point AA, perpendicularly therefrom and arrives at an edge of a second line, e.g., line  102 L at nearby closest feature  16 . 
     Point B, found in FIG. 1 between isolated line  2 L and line  3  has also been vertically shifted upward to become point BB due to line  3  vertical/lateral enhancement  42 . It can also be seen that the distance between point BB and nearby closest feature  117  as well as the distance between point BB and distant closest feature  124  are each substantially the preferred distance α 1 . By these enhancements, it can be seen that substantially any point of metallization between an arbitrary given point and a nearby closest feature will have a distance equal to about α 1 . 
     Where point AA lies between two parallel features separated by the distance of about α 1 , the problem of excess reflectance during photolithographic layout of metallization line layout  10  is substantially inconsequential. At point B, as illustrated in FIG. 1, the effect of excess reflectance during photolithographic layout of metallization line layout  10  has been diminished by the formation of point BB due to the addition of line  2 L vertical enhancement  40  and line  3  vertical/lateral enhancement  42 . Thereby, the excess reflectance effect of enclosed exposure  18 , as seen in FIG. 1, is substantially diminished such that any given distance from point BB to a nearby closest feature, e.g.,  117  or a distant closest feature  124 , is substantially α 1 . 
     Not every arbitrarily selected point upon every metallization line can be separated by a nearby closest feature by a distance of about α 1 . Where the metallization line layout creates such features seen in FIG. 1 as enclosed exposures  18  and  19 , open exposures  20  and  21 , and terminal end exposures  22  and  23 , another embodiment of the present invention reduces the detrimental effect of excess reflectance by staggering the occurrence of intersections between enhancement features where some intersection exposure is unavoidable. According to this embodiment, where a distance greater than α 1  occurs between an arbitrarily chosen point and its closest feature after the inventive metallization line enhancement, the point found perpendicularly across the metallization line on the opposite edge of the arbitrarily chosen point will have a distance between that opposite edge and its closest feature of no greater than approximately α 1 . This embodiment is illustrated by observing exposure upon metallization lines. By way of example, reference is made to FIG. 2, points EE and EE′, and points G and G′. 
     At point EE′, upon enhanced line  103  in FIG. 2, it can be seen that a first enclosed exposure  62  exists at a region in a downward vertical direction from point EE′. The existence of first enclosed exposure  62  causes the likelihood of excess reflectance at point EE′ during photolithographic layout of metallization line layout  10 , such that a metallization line-thinning amount of excessive reflectance during light exposure might occur at point EE′. According to this embodiment of the present invention, the occurrence of line  3  vertical/lateral enhancement  42  minimizes the amount of unavoidable excess reflectance upon enhanced line  103  at the region exactly opposite (upwardly vertically depicted) from point EE′, namely at point EE. It can be seen that point EE lies perpendicularly opposite point EE′ across the major axis of enhanced line  103 . Thus, point E, seen in FIG. 1, has been enhanced to reduce excess reflectance vulnerability of line  3 . 
     In FIG. 2, the effect of reducing excess reflectance at point G is accomplished by staggering unavoidable intersections that must occur where isolated metallization lines have an end  111 . When so staggered, the distance γ 2  is greater than α 1  but less than the distance γ 0 . This can be seen by example as the distance between point G′ on one edge of enhanced line  103  and line  4 L corner enhancement  46 , γ 2 , and the distance between point AA on another edge of enhanced line  103  and point  16 , α 1 . 
     Point G, opposite to point G′, upon enhanced line  103  is subjected to a reflectance exposure distance of only α 1 . However, above enhanced line  103 , it can be seen that a second open exposure  66  has been left above a point H due to the presence of ends  111  of enhanced lines  102 L,  102 R to form an intersection. By comparison of the relative positions of first continuous line exposure  64  below point G′ and second continuous line exposure  66  above point H, it can be seen that the occurrence of unavoidable exposures that expose enhanced line  103  have been horizontally offset from vertical edges  11  by a varying amount, and staggered among themselves. The offset distance between exposures is preferably greater than or equal to about α 1  although it can be less, but not allowing exposures to vertically align. As such, no single segment of a metallization line will be subject to two exposures on exactly opposite sides thereof, such as points G and G′, where G illustrates a point that is not exposed and is separated by α 1  from a nearby closest feature on enhancement  38  of line  102 L, and G′ illustrates a point that is exposed at a distance γ 2  from the nearby closest feature in corner enhancement  46  of line  104 L, where γ 2 &gt;α 1 . 
     As seen in FIG. 1, the occurrence of terminal end exposures  22  and  23  also cause significantly greater amounts of reflectance that affect at least ends  11  of isolated metallization lines. The effect of staggering unavoidable exposures accomplishes both the resistance of unwanted thinning of terminal ends of isolated metallization lines, and likewise minimizes unavoidable reflectance to continuous metallization lines due to the presence of at least one open exposure. Thus, for enhanced line  103 , first open exposure  64  may cause some weakening of enhanced line  103  at point G′, but because second open exposure  66  is horizontally shifted away from point G on continuous line  103 , by a distance preferably at least as great as α 1 , the effect of excess reflectance upon continuous line  103  at the localized line segment encompassing points G and G′ is reduced by at least 50 percent. 
     It can thus be seen that the present invention accomplishes both the standardization of distances from any given point to its nearest closest feature not of the same metallization line, and, where it is unavoidable that a given point upon a metallization line will have an exposure, i.e., a closest feature located at a distance that is greater than the standardized distance α 1 , this exposure will occur only on one side of the metallization line within a lateral distance of at least α 1 . 
     FIG. 3 illustrates an improved metallization line layout  210  that is one embodiment of a metallization line layout as it would be prepared, by way of example, by a photolithographic process. It can be seen that a series of improved isolated metallization lines and improved continuous metallization lines appear to have somewhat arbitrary shapes. The shapes are methodically produced, with some variation possible, e.g., locating an intersection by shifting left instead of right, when presented with a given metallization line layout for a given device array. 
     Absent from the present invention is the occurrence of any cross-shaped, 4-way, or 6-way intersections created by at least four corners of metallization line features that are defined by having ends within a given localized area. It can be seen in FIG. 3 that the classic “Manhattan” layout of metallization lines is not present where no intersection in the present invention comprises a 4-way or 6-way intersection. 
     FIG. 4 is an enlarged detail section taken from FIG. 3 along the line  4 — 4 . Therein it can be seen that ends  211 ,  311 ,  411 , and  511  each have a distance from either of vertical boundaries  115 ,  115 ′ that differs from any other of the ends. It can also be seen that each isolated line in FIG. 4 has an end  211 ,  311 ,  411 , and  511 , that has a length. It can also be seen that every isolated line end length is parallel to every other isolated line end length. Further, it can be seen that any parallel projection from any isolated line end length that intersects with its nearest neighboring metallization line is substantially the uniform distance α 1  for all parallel-to-end-length projections therefrom. It can also be seen that no projection from any end namely any isolated line end length, projects through an exposure between adjacent isolated lines. 
     A corner may be defined as an edge of a line that begins at a boundary, that meets a first right angle direction change and that terminates at a second right angle direction change or at a second boundary. Thus, point I is a corner apex. This corner may be defined as beginning on improved line  205 L at left vertical boundary  15 ′ on its upper edge, meeting a first right angle direction change at point I, and terminating at a second right angle direction change at I′. It can also be seen in FIG. 4 that for a given point such as a point I, taken from an end  211  corner of improved line  205 L, there is a distance to the nearby closest features J and K of about α 1 . Further, it can be seen that the distance between nearby closest features J and K will have a distance of about β 1 , wherein β 1  is equal to about {square root over (2)} α 1 . Thus, for nearby closest feature J itself, it has a nearby closest feature I, at a distance of α 1 . Because point I is at end  211  of improved line  205 L, it also has a nearby distant feature K, at a distance of β 1 , or {square root over (2)} α 1 . 
     FIG. 5 is a detail section taken from FIG. 3 along the line  5 — 5 . Therein, it can be seen that right angle direction change features occur to define corners where either the metallization line changes in overall direction or changes in width. Thus, in FIG. 5, improved line  202 L at its lower edge begins to define a corner at left boundary  215 ′, meets a first right angle direction change at inside corner apex  79 , continues vertically downward along a right angle direction change edge  233 , and terminates at nearby closest feature  216 . Improved line  201 L also has a right angle direction change edge  213  that has a length and that is also parallel to vertical boundaries  215 ,  215 ′. In a like manner, improved line  202 L has right angle direction change edges  223  and  233 . Improved line  203  has right angle direction change edges  243  and  253 . Additionally, improved line  204 L has right angle direction change edges  263  and  273 . In each case, the right angle direction change edge has a length and the length runs substantially parallel to vertical boundaries  215 ,  215 ′. 
     First enclosed exposure  62  is formed by right angle direction change features  253  and  263 . It can be seen that second enclosed exposure  63  is configured so as to have a horizontal distance from vertical boundary  215  that is different from first enclosed exposure  62 . Similarly, improved line  203  forms an outside corner beginning at upper edge at left vertical boundary  215 ′, meets first right angle direction change end  243  at a first outside corner apex  78 , continues vertically downward along right angle direction change edge  243 , and terminates at the next right angle which is an inside corner apex  219 . 
     It can be seen in FIG. 5 that between improved lines  201 L and  202 L, a first distance  74  that is substantially equal to α 1  is found by taking a line that is substantially perpendicular to the parallel features of improved lines  201 L and  202 L, but that a second distance  76  appears to be less than first distance  74  and thus likewise less than the distance α 1 . The occurrence of first distance  74  and second distance  76  is acceptable within the scheme of the present invention, wherein the variation of second distance  76  in comparison to first distance  74  is such that distance  76  is about 90% of distance  74 , preferably about 96%, more preferably about 98%, and most preferably greater than 99%. The exact amount of variance between first distance  74  and second distance  76 , as it may occur throughout improved metallization line layout  210 , will depend upon the specific application and will depend upon process goals. 
     It can also be seen in FIG. 5 that a diagonal distance β 1  appears as being a measurement between outside corner apex  78  of improved line  203  and an inside corner apex  79  of improved line  202 L. The distance β 1 , however, is not the smallest distance between outside corner apex  78  of improved line  203  and its nearest neighboring feature. Rather, the nearby closest features are seen at  216  and  217 . Nearby closest features  216  and  217  are separated from outside corner apex  78  of improved line  203  by a distance of about α 1 . By this illustration it can be seen that, although the distance β 1  may be present in the improved metallization line layout  210  seen in FIG. 3, the nearest feature to outside corner apex  78  is nearby closest feature  216  or feature  217 . It is also preferable that distance β 1 , is substantially equal to {square root over (2)}α 1 . 
     Another way of describing the structure seen in FIG. 5 is to call improved line  203  a first continuous line having a first convex edge defined by corner apex  78 . Improved line  202 L may be called a second continuous line having a concave edge defined at inside corner apex  79 . First continuous line  203  is adjacent to second continuous line  202 L and is spaced apart therefrom by a distance of about α 1  where adjacent edges are substantially parallel. Further, inside corner apex  79  of the first concave edge is separated from outside corner apex  78  of the first convex edge by a diagonal distance of about {square root over (2)}α 1 . It is further clear that a projection from the first convex edge, defined at edges encompassing outside corner apex  78 , to second continuous line  202 L has a distance of about α 1 . It is further seen that first continuous line  203  has a second convex edge, defined at edges encompassing second outside corner apex  88  on an edge opposite the first convex edge. The structure in FIG. 5 is further defined by a third continuous line, in this case improved line  204 L having a concave edge defined at inside corner apex  89 . First continuous line  203  is adjacent to third continuous line  204 L and opposite second continuous line  202 L. Inside corner apex  89  of the concave edge of third continuous line  204 L is separated from second outside corner apex  88  of the second convex edge by the distance of about {square root over (2)}α 1 . Further, vertical projections from respective corners of the first and second convex edges of first continuous line  203  to nearest adjacent continuous lines  202 L,  204 L respectively are measured by a distance of about α 1 . 
     Another embodiment of the present invention may be approximated in FIG. 5, wherein arcuate shapes are formed in the place of right-angle inside and outside corners. For example, where diagonal distance β 1  appears as being a measurement between outside corner apex  78  of improved line  203  and an inside corner apex  79  of improved line  202 L, an arcuate shape for both outside corner apex  78  and inside corner apex  79  would allow the value of distance of β 1  to approach the preferred distance of α 1 . The decrease of distance β 1  to approach the preferred distance of α 1  comes about by causing inside corner apex  79  to soften into a semicircular arc that may begin at near nearby closest feature  217  and that may end near nearby closest feature  216 . Similarly, outside corner apex  78  may be softened into a semicircular arc of the same approximate arc length as that formed in place of inside corner apex  79 . As such, all right-angle features are replaceable with arcuate features that may cause substantially all closest distances between lines to be about equal to about α 1 . 
     The improved metallization line layout, as seen in FIG. 3, or in detail in FIGS. 4 and 5, may include at least one of three possible distinct features. The first possible distinct feature, seen in FIGS. 3 and 4, is an offset, double 3-way intersection that is created by offsetting exposures that were caused by the adjacent occurrence of open exposure  21  and end exposures  22  and  23  seen in FIG.  1 . 
     As seen in FIG. 4, a first 3-way intersection, located within an arbitrary subregion  250 , is created near second open exposure  64 . Thus in FIG. 4, improved line  204 L is a first metallization line having a first end  311 . Improved line  204 R is a second metallization line having a second end  411 . The respective first and second metallization lines, improved lines  204 L and  204 R have at least one edge and are substantially collinear at respective first and second ends  311 ,  411 . The first and second ends  311 ,  411  are separated by a first distance α 1  to form second open exposure  64  that exposes improved line  203 . 
     This first 3-way intersection is completed by the presence of a third metallization line: improved line  205 L. The third metallization line has an end  211  and is spaced apart from end  311  of line  204 L by a distance of at least about 2α 1 . End  211  is also spaced apart from end  411  of line  204 R by the distance of about α 1 . In other words, the third metallization line  205 L is separated from at least one of the first and second metallization lines equivalent to the first distance, α 1  and end  211  is laterally offset from ends  311  and  411 , by an amount greater than or equal to the first distance, α 1 . It is seen further that a projection from at least one end  311 ,  411  intersects third metallization line  205 L at its upper edge. 
     The second 3-way intersection, located within an arbitrary subregion  260 , is created near third open exposure  68 . Accordingly, a fourth metallization line having an end  511  is provided. Where the third metallization line is line  205 L, the fourth metallization line is line  205 R. The third and fourth metallization lines may have at least one edge that are substantially collinear near ends  211 ,  511 . The ends  211  and  511  are separated by about first distance a, to form second open exposure  68 . First open exposure  64  upon improved line  203  and second open exposure  68  upon improved line  206  are laterally offset from each other when measured from either boundary  115 ,  115 ′, by at least the first distance α 1 . In other  11  words, each exposure occurs at different distances from either of vertical boundaries  115 ,  115 ′. The double 3-way intersection is thus defined at ends  211 ,  311 ,  411 , and  511  by spaces between metallization lines that make up two adjacent, offset open exposures  64  and  68 . 
     A second possible distinct feature is the formation of a 3-way intersection by the presence of two isolated improved lines with an open exposure and an improved continuous line. Such a 3-way intersection, located within an arbitrary subregion  270 , includes second open exposure  64  upon improved line  203 . In FIGS. 3 and 4, improved line  204 L is a first metallization line having end  311 . Improved line  204 R is a second metallization line having end  411 . The first and second metallization lines, improved lines  204 L and  204 R have at least one edge are substantially collinear near ends  311  and  411 . Ends  311  and  411  are separated by first distance a, to form second open exposure  64 . This 3-way intersection is completed by the presence of a third metallization line: improved line  203 . The third metallization line is adjacent and spaced apart parallel to the first and second metallization lines. In this example, third metallization line  203  lies parallel to collinear edges of improved lines  204 L and  204 R. Third metallization line  203  is separated from at least one of the first and second metallization lines by first distance, α 1 . This intersection is formed by including a portion of first open exposure  64 , respective ends  311  and  411  of improved lines  204 L and  204 R, and continuous line  203 . 
     A third possible distinct feature is illustrated in FIG.  5 . This feature is the formation of metallization lines around an enlarged feature such as enlarged feature  13  that avoids detrimental enclosed exposures  18  and  19  as seen in FIG.  1 . This third possible distinct feature can be described as a first metallization line such as improved line  203  that has first outside corner apex  78  and a second outside corner apex  88 . Second outside corner apex  88  is upon a side of improved line  203  that is opposite the first outside corner apex  78 . A second metallization line such as improved line  202 L has a right-angle direction change edge  233  that forms inside corner at  79 , that is complementary in shape to first outside corner at  78 . The second metallization line is separated before right-angle direction change edge  233  at first outside corner apex  78  from its nearby closest features  216 ,  217  each by first distance, α 1 . The second metallization line is also separated at inside corner apex  79  by a second distance, β 1 , equal to about 1.4 times first distance a, (about {square root over (2)} α 1 ) at right-angle direction change edge  233 . A third metallization line such as improved line  204 L has a right angle direction change edge  263  that forms an inside corner apex  89  that is complementary in shape to second outside corner apex  88 . The third metallization line is vertically separated from the second outside corner apex  88  by first distance α 1  before the right-angle direction change and diagonally separated by second distance β 1  between inside corner apex  89  and second outside corner apex  88 . It can be seen that first enclosed exposure  62  and second enclosed exposure  63  are laterally offset from each other, when measuring their distances from either of boundaries  215 ,  215 ′, by at least distance α 1 . Thus, where right-angle direction change edge  253  is a given distance from left boundary  215 ′, right-angle direction change edge  243  is the given distance from left boundary edge  215 ′, plus at least the distance α 1 . 
     FIG. 6 illustrates the inventive metallization line layout as it appears in an embodiment where a prior art 3-way intersection, such as that seen in FIG. 1A, has been enhanced. The 3-way intersection consisted of two continuous lines  72 ,  73  and one interposed isolated line  70 . Enhancement of vertical portions of lines  72  and  73 , line  72  being downwardly vertical to the right of end  311  and line  73  being upwardly vertical to the right of end  311 , has resulted in the reduction of exposure and of likely excess reflectance. Thus, a measured perpendicular distance taken from end  311  of line  70  to nearby closest features  316 ,  317 , or features  378 ,  388 , either vertically or horizontally, results in a measured distance of α 1 . 
     FIGS. 7A,  7 B, and  7 C illustrate cross-sectional views of the improved metallization line layout seen in FIG. 3, taken along the lines S—S, T—T, and U—U, respectively. Therein, it can be seen that both isolated and continuous lines have been covered with an interlayer dielectric layer (IDL)  80  that has a substantially planar upper surface  82  and is characterized by substantially fused trenches  84 . Although it appears that the space between some features such as improved line  204 L and improved line  203  in cross-section S—S is greater than elsewhere, the formation of substantially planar upper surface  82  is caused due to the location of distant closest features that are at a distance of no more than about {square root over (2)} α 1  or about 1.4α 1 . Thus, trench filling is substantially uniform to cause the formation of substantially planar upper surface  82  upon deposition of IDL  80 . 
     The open depth of each occurrence of fused trench  84 , open to planar upper surface  82 , in order to make planar upper surface  82  substantially planar as far as the fabricator is concerned during subsequent fabrication thereof, is related to the line elevation  400  of the metallization lines. For example, improved line  4 L, seen in FIG. 7 a , has a line elevation  400 . Fused trench  84  above and to the left of improved line  4 L, has a trench depth  402 . Preferably, fused trench depth  402  is about one half the depth equivalent to the amount of line elevation  400 . Preferably, it is about ⅕ the depth more preferably about {fraction (1/10)}th the depth, even more preferably about {fraction (1/100)}th the depth of line elevation  400 , and most preferably about {fraction (1/1000)}th the depth of line elevation  400 . 
     In review, it can be seen that the present invention provides an improved metallization line layout upon a semiconductor device including metallization lines each having at least one width and each having a length. 
     The improved metallization line layout creates offset exposures to minimize the unavoidable excess reflectance. The improved metallization line layout of the present invention also creates standard distances from any selected point upon an edge of a line to any nearby closest feature or to any nearby distant feature if present. The establishment of these standard distances allows for formation of an interlayer dielectric layer (IDL) that, when formed or deposited at a selected thickness upon the improved metallization line layout of FIG. 3, will result in a substantially planarized upper surface without the need for further processing. The substantially planarized upper surface eliminates the need for further processing of the IDL by properly dimensioning the spacing between nearest diagonally adjacent metallization features as described above. As such, there is an assurance that the IDL will cover a center point therebetween by the formation of fused trenches so as to be substantially planarized at the top surface thereof at a like height to the IDL over metallization features in the layout. 
     By implementing the present invention, the height of the top surface of the IDL will be the same over open spacing areas as well as over metallization features, and a substantially planarized IDL with fused trenches between metallization features will result after a single thin deposition of the IDL. By standardizing the spacing between nearest metallization features, and by standardizing the raise amount of the metallization lines in relation to the IDL thickness improved processing throughout an integrated circuit structure will result. A lesser amount of metal has to be etched which shortens etch processing time and increases throughput. The more uniform distribution of the metallization and non-metallization areas will also avoid local perturbations of a plasma during dry etching of the improved metallization line layout. Additionally, the upper surface of the IDL will be substantially planar without further processing. 
     With respect to deposition of an IDL, the present invention makes it possible to use a thinner layer of intermetal dielectric in that the spacing between metallization features is smaller due to its standardization. Thus, where conventional techniques like photoresist etchback or chemical-mechanical polishing (CMP) require an IDL having a conventional thickness, the present invention enables the deposition of an IDL having a thickness of less than about 80% the conventional thickness, preferably less than about 70%, more preferably less than about 50%, and most preferably about 40%. Conventional IDL deposition thicknesses are about 12,000 Å before etchback or CMP. The thinner IDL made possible by the present invention will require less deposition time and less material usage. Thus, a shorter throughput time results. In some embodiments, IDL thicknesses for the present invention, in order to achieve a substantially planarized upper surface upon deposition, are about one half the value of α 1 . 
     A method of fabricating an improved metallization line layout includes providing a given metallization line layout and practicing the inventive method. According to the inventive method, the fabricator receives a required metallization line layout scheme for a given device array. A point is chosen between two parallel metallization line features and the distance therebetween is determined. The distance is given a value of α 0  and it is determined whether α 0  is equal to or greater than a preferred distance α 1 . Where the distance is greater than the preferred distance α 1 , at least one vertical feature of at least one metallization line is enhanced until the distance between the two parallel features is substantially α 1 . 
     Where a metallization line has an end, thus creating isolated lines, the lateral distance between an end of an isolated line and its lateral counterpart (e.g. such as the distance between isolated lines  2 L and  2 R) are brought nearer by the horizontal enhancement of at least one end thereof. Where two isolated lines such as isolated lines  2 L and  2 R are adjacent to a continuous line such as line  3 , a lateral enhancement such as line  2 L vertical/lateral enhancement  38  shifts end  11  of line  2 L to the right, and the layout of isolated lines  4 L and  4 R will have caused end  11  of isolated line  4 R to be enhanced by shifting end  11  to the left. Thereby, FIGS. 2 and 3 illustrate that open exposures  20  and  21  are eliminated and are replaced with only first open exposure  64 . 
     In some applications of the present invention, a non-Manhattan style layout may occur. In other words, where metallization lines are not all oriented with right-angle direction changes, non 90-degree features may be necessary for completing circuits. FIG. 8 illustrates a non-Manhattan style layout  810  as a possible subset of a larger layout. Layout  810  has metallization lines that have direction changes that are not orthogonal. A symmetry line  872  is depicted as being equidistant from respective parallel edges  874 ,  876  of a metallization line such as isolated line  804 L. Symmetry line  872  illustrates that a metallization line  804 L is symmetrical about symmetry line  872  and symmetry line  872  has a non-orthogonal direction change to form a non-orthogonal angle. 
     For example, an angle  870  is depicted as being about 65 degrees; in any event, angle  870  is not orthogonal. Angle  870  may be in a range from about 1 degree to about 89 degrees. Angle  870  more preferably is in a range from about 10 degrees to about 80 degrees. Typically, the angle such as angle  870  will be about 45 degrees where possible. The specific degree of the angle that defines a direction change in a metallization line will depend upon layout requirements. 
     FIG. 8 illustrates the inventive method and layout. Enlargement of metallization lines during the designing and preparation of a metallization line layout  810  according to the present invention is similar to the illustrated discussion of FIG.  2 . Layout  810  has an arbitrary region Z imposed upon it for illustrative purposes. FIG. 8 also illustrates that enhancement of metallization lines may take a reference from an existing continuous metallization line such as a metallization line  803  or a metallization line  805  within the arbitrary region Z. As such, parallel edges of enhancements may lie parallel with parallel horizontal boundaries  817  and  817 ′. Likewise, parallel ends of enhancements may lie parallel with parallel vertical boundaries  815  and  815 ′. 
     FIG. 8 illustrates that isolated metallization lines and continuous metallization lines have been enhanced by material during the design process. Additionally, FIG. 8 illustrates a perimeter metallization line  832  that has been formed next to two otherwise exposed isolated metallization lines,  801 L and  801 R. In other words, but for the presence of perimeter metallization line  832 , metallization lines  801 L and  801 R would have been subject to both terminal-end exposures and lateral exposures such as those illustrated in FIG.  1 . 
     Metallization line  801 L has been enhanced by a lateral enhancement  834 . Metallization line  801 R has been enhanced by lateral enhancement  836 . Lateral enhancement  834  extends the end  211  toward metallization line  801 R and lateral enhancement  836  extends the end  311  toward metallization line  801 L. Optionally, either of metallization lines  801  may be extended without the other where neighboring metallization lines may allow in order to achieve a preferred distance between ends of about α 1  as set forth above. Each of end  211  and end  311  have a length that is parallel to parallel vertical boundaries  815  and  815 ′. Further, ends  211  and  311  are spaced apart by the preferred distance of about α 1  as set forth above. 
     Metallization line  802 L has been enhanced by a lateral enhancement  838 . Metallization line  802 R has been enhanced by an angular enhancement  840  that causes its end  411  to lie parallel to the end  511  of lateral enhancement  838  of metallization line  802 L. Each of end  411  and end  511  have a length that is parallel to parallel vertical boundaries  815  and  815 ′. Further, ends  411  and  511  are spaced apart by the preferred distance of about α 1  as set forth above. 
     Metallization line  803  has been unchanged as illustrated in FIG.  8 . Metallization line  804 L has been enhanced by a vertical/lateral enhancement  842 . The vertical portion of the enhancement closes the spaced-apart distance between metallization line  803  and metallization line  804 L to a preferred distance such as about α 1  as set forth above. Metallization line  804 R has been enhanced by a vertical/lateral enhancement  844 . The vertical portion of enhancement  844  closes the distance between metallization line  804 R and the metallization line  805  to the preferred distance of about α 1  as set forth above. Additionally, the lateral enhancements of enhancements  842  and  844  also have parallel ends  611  and  711 , respectively. Further, ends  611  and  711  are spaced apart by the preferred distance of about α 1  as set forth above. As a result, continuous metallization line open exposures  866  and  868  on metallization line  803  are reduced to the minimum as discussed above. Further the ends  411  and  511  are set at different distances than the ends  611  and  711  or the ends  211  and  311 , from either of parallel vertical boundaries  815 ,  815 ′ of arbitrary region Z. 
     Metallization line  805  is a continuous metallization line that has an open exposure  864  that has been reduced to the preferred minimum by the placement of enhancements  842  and  844  according to the present invention. FIG. 8 illustrates that ends  211 ,  311 ,  411 ,  511 ,  611 , and  711  each have a distance from either of vertical boundaries  115 ,  115 ′ that differs from any other of the ends. However, either of end  211  or end  311  may have the same distance from either of vertical boundaries  115 ,  115 ′ where two metallization lines, such as metallization line  802 L and metallization line  803  lie therebetween. It is only preferred to avoid any open exposures upon any given metallization line directly across from any other open exposure on that metallization line. 
     FIG. 8 also illustrates that each isolated metallization line has an end that has a length. It can also be seen that every isolated metallization line end length is parallel to every other isolated metallization line end length. Further, it can be seen that any parallel projection from any isolated metallization line end length that intersects with its nearest neighboring metallization line is substantially the uniform distance α 1  for all parallel-to-end-length projections therefrom. It can also be seen that no projection from any end, namely any isolated metallization line end length, projects through an exposure between adjacent isolated metallization lines. 
     Similar to what is illustrated in FIG. 4, comparison of the relative positions of continuous metallization line exposures  864 ,  866 , and  868  illustrates that the occurrence of unavoidable exposures that expose continuous metallization lines  803  and  805  within arbitrary region Z, have been horizontally offset from vertical edges  15  by a varying amount, and staggered among themselves. The offset distance between continuous metallization line exposures is preferably greater than or equal to about α 1  although it can be less, but not allowing exposures to vertically align. As such, no single segment of a metallization line will be subject to two exposures on exactly opposite sides thereof as discussed above. 
     The inventive method of fabricating a metallization line layout may be summarized by providing a preliminary metallization line layout, and detecting spaces between a first metallization line and an adjacent second metallization line. After detecting spaces, the method continues by measuring a perpendicular distance between adjacent edges of the first metallization line and the second metallization line, wherein the adjacent edges are a first edge on the first metallization line closest to the second metallization line and a second edge on the second metallization line closest to the first metallization line. Next the perpendicular distance is compared to a preferred distance, and a portion of at least one of the first edge and second edge is selected if the perpendicular distance is less than the preferred distance. After comparing, shifting of at least one of the first edge and second edge is carried out in a direction to cause the perpendicular distance to approach the preferred distance. After the distances have been narrowed to the preferred distance, patterning of the metallization line layout is carried out. 
     Additionally, dummy metallization lines may be placed upon the layout where spaces between electrically conductive lines are significantly large. The dummy metallization lines may be placed in lieu of electrically conductive metallization line enhancement. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrated and not restrictive. The scope of the invention is, therefore, indicated by the appended claims and their combination in whole or in part rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.