Method for forming alignment marks - Patent Application 20070122997

Abstract

A method for forming alignment marks takes advantage of pad density and critical dimensions (CD). In some embodiments, the method includes forming first and second alignment marks on a first substrate and a second substrate, the first and second alignment marks having widths within 5% of associated CDs of copper pads on the respective substrates, and forming first and second dummy patterns around the first and second alignment marks. The first and second dummy patterns have a dummy pattern density within 5% of the density of copper pads on the first and second substrates, and a CD within 5% of the CD of the respective copper pads. In some embodiments, alignment marks with protrusions and recesses of physical dielectric material on opposing substrate surfaces can further improve bonding.

Description

[Technical Field]

[0001] FIELD Embodiments of the present principles relate generally to semiconductor processing of semiconductor substrates. [Background technology]

[0002] During the fabrication of semiconductor components, the components often need to be aligned for proper process operation. Alignment is necessary for lithography processes, metrology processes, and / or bonding processes, etc. Generally, alignment marks or symbols are used to indicate whether an overlay or another substrate is properly aligned. However, alignment marks are often spaced apart from areas containing major semiconductor devices or critical lithography areas to prevent them from interfering with the semiconductor design or layout. The inventors have observed that in some situations, alignment mark areas can unintentionally cause component fabrication problems due to the placement and separation of the alignment marks.

[0003] Thus, the inventors have provided a method for forming high performance alignment marks that facilitates reducing component manufacturing problems. Summary of the Invention

[0004] SUMMARY OF THE INVENTION A method for forming high performance alignment marks for semiconductor manufacturing is provided herein.

[0005] In some embodiments, a method for forming alignment marks includes forming a first alignment mark on a first substrate, the first alignment mark having a first width within 5% of a critical dimension (CD) of a first copper pad on the first substrate; forming a first dummy pattern of first dummy copper pads on the first substrate around the first alignment mark, the first dummy pattern having a density of the first dummy pattern within 5% of a density of the first copper pads on the first substrate, and the first dummy copper pads having CDs of the first dummy copper pads within 5% of a CD of the first copper pads on the first substrate; and forming a second alignment mark on a second substrate, the second alignment mark having a CD of the first dummy copper pads within 5% of a CD of the first copper pads on the first substrate. forming a second alignment mark having a second width within 5% of a critical dimension (CD) of a second copper pad on the second substrate; and forming a second dummy pattern of second dummy copper pads on the second substrate around the second alignment mark, wherein the second dummy pattern has a density of the second dummy pattern within 5% of the density of the second copper pads on the second substrate and the second dummy copper pads have CDs of the second dummy copper pads within 5% of the CDs of the second copper pads on the second substrate, wherein the second alignment mark nests within the first alignment mark in a top-down view without border overlap when the second substrate is overlaid on or under the first substrate, resulting in a predetermined alignment between the first substrate and the second substrate.

[0006] In some embodiments, a method for forming alignment marks includes forming a first alignment mark on a first substrate, the first alignment mark having a first width within 5% of a critical dimension (CD) of a first copper pad on the first substrate; forming a first dummy pattern of first dummy copper pads on the first substrate around the first alignment mark, the first dummy pattern having a density of the first dummy pattern within 5% of a density of the first copper pads on the first substrate and the first dummy copper pads having a CD of the first dummy copper pad within 5% of the CD of the first copper pads on the first substrate; and forming a second alignment mark on a second substrate, the second alignment mark having a second width within 5% of a critical dimension (CD) of the second copper pad on the second substrate. forming an alignment mark; and forming a second dummy pattern of second dummy copper pads on the second substrate around the second alignment mark, the second dummy pattern having a density of the second dummy pattern within 5% of the density of the second copper pads on the second substrate, and the second dummy copper pads having CDs of the second dummy copper pads within 5% of the CDs of the second copper pads on the second substrate, wherein the second alignment mark nests within the first alignment mark in a top-down view without border overlap when the second substrate overlies or underlies the first substrate, resulting in a predetermined alignment between the first and second substrates, and the second alignment mark is positioned about 5 microns to about 10 microns from the first alignment mark to allow for alignment shift when located within the first alignment mark from a top-down view.

[0007] In some embodiments, a non-transitory computer-readable medium having stored thereon instructions that, when executed, cause a method for forming alignment marks to be performed, the method including: forming a first alignment mark on a first substrate, the first alignment mark having a first width within 5% of a critical dimension (CD) of a first copper pad on the first substrate; forming a first dummy pattern of first dummy copper pads on the first substrate around the first alignment mark, the first dummy pattern having a first dummy pattern density within 5% of a density of the first copper pads on the first substrate and the first dummy copper pads having a first dummy copper pad CD within 5% of a CD of the first copper pads on the first substrate; forming a second alignment mark on a second substrate; forming a second alignment mark, the second alignment mark having a second width within 5% of a critical dimension (CD) of a second copper pad on the second substrate; and forming a second dummy pattern of second dummy copper pads on the second substrate around the second alignment mark, the second dummy pattern having a density of the second dummy pattern within 5% of a density of the second copper pads on the second substrate, and the second dummy copper pads having CDs of the second dummy copper pads within 5% of the CDs of the second copper pads on the second substrate, wherein the second alignment mark nests within the first alignment mark in a top-down view without border overlap when the second substrate overlies or underlies the first substrate, resulting in a predetermined alignment between the first and second substrates.

[0008] Other and further embodiments are disclosed below.

[0009] Embodiments of the present principles, briefly summarized above and described in more detail below, can be understood by reference to exemplary embodiments of the present principles as illustrated in the accompanying drawings. However, since the present principles may admit of other equally effective embodiments, the accompanying drawings illustrate only general embodiments of the present principles and therefore should not be considered limiting in scope. [Brief explanation of the drawings]

[0010] [Figure 1] 1A-1C are cross-sectional and top-down views of alignment marks, in accordance with some embodiments of the present principles; [Figure 2] FIG. 1 is a bottom-up view of a chip, in accordance with some embodiments of the present principles. [Figure 3] FIG. 1B is a bottom-up view of bonding voids in a chip, in accordance with some embodiments of the present principles. [Figure 4] 1 is a top down view of an alignment mark and contact pad area of ​​a substrate, in accordance with some embodiments of the present principles; [Figure 5] 1 is an isometric view and a graph of a portion of a substrate with alignment marks, in accordance with some embodiments of the present principles; [Figure 6] 10A-10C show alignment marks with parting lines, in accordance with some embodiments of the present principles; [Figure 7] 1A-1C show alignment marks with dummy patterns, in accordance with some embodiments of the present principles; [Figure 8] 1 is an isometric view and a graph of a portion of a substrate with alignment marks, in accordance with some embodiments of the present principles; [Figure 9] FIG. 1 is a top-down view of an alignment mark, in accordance with some embodiments of the present principles; [Figure 10] 1A-1C are diagrams of methods for forming alignment marks, in accordance with some embodiments of the present principles; [Figure 11]1A-1C are isometric, top-down, and graphical views of an alignment mark using a lock-and-key technique with protrusions, in accordance with some embodiments of the present principles; [Figure 12] 10A-10C are isometric, top-down, and graphical views of an alignment mark with a recess and using a key and lock approach, in accordance with some embodiments of the present principles; [Figure 13] 10A-10C are cross-sectional views of aligning a substrate with an alignment mark having a protrusion over a substrate with an alignment mark having a recess, according to some embodiments of the present principles; [Figure 14] 1A-1C are cross-sectional views of a substrate with an alignment mark having a protrusion aligned to a substrate with an alignment mark having a recess, in accordance with some embodiments of the present principles; DETAILED DESCRIPTION OF THE INVENTION

[0011] For ease of understanding, the same reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0012] The present methods provide improved alignment marks for semiconductor manufacturing processes, such as bonding, lithography, and / or metrology processes. In some embodiments, the alignment marks and areas are based on, for example, chip pad parameters to dramatically reduce chemical-mechanical polishing (CMP) defects that affect the performance of semiconductor components throughout the manufacturing process. For example, the methods of the present principles can be used to modify reference design rules when CMP processing is used prior to hybrid bonding applications. The present principles beneficially provide, for example, uniform bond strength across the bonded chip and substrate, eliminating weak bond areas and significantly improving the reliability of the packaged chip.

[0013] The inventors discovered that some manufacturing issues are directly related to the reference design layout. For example, in hybrid bonds, voids were found near the fiducials. Current CMP processes focus on process tuning, such as using the best slurry combination, and process knob adjustments, such as polishing pressure and polishing time. However, CMP processes do not address the fiducials and their impact on the performance of the manufacturing process. To minimize the adverse effects of the reference design layout, the inventors discovered that the key CMP requirements for achieving successful hybrid bonds for both bond pads and fiducials include dishing of less than about 5 nm for a post-bond annealing temperature of about 350 degrees Celsius, minimum dielectric rounding of less than about 3 nm, a dielectric surface roughness or Ra of less than about 0.5 nm per 10 μm × 10 μm surface area, and the absence of barrier protrusions. Dielectric rounding around the fiducial area is particularly important because that area is typically isolated from the main bond pad array; therefore, large dielectric portions without contact pads affect bond quality. To achieve the CMP parameters, the fiducial area layout is expanded to create a more uniform surface during CMP processing. In some embodiments, the fiducial areas are formed so that the fiducials (alignment marks) and fiducial areas have copper critical dimensions (CDs) similar to the CDs of the chip pads (connection areas). Furthermore, the fiducial area density has a density similar to the chip pad density. By closely matching the CDs and densities (within about 5%), the CMP process will produce similar surface performance not only for the chip pad surface, but for the entire chip surface.

[0014] As used herein, “alignment mark” is used as a general term to include fiducials and the like used to align or center one or more objects relative to one another or to a standard. The alignment marks described herein may be used in bonding alignment, overlay alignment, metrology alignment, and the like. For simplicity, the alignment marks are described in the context of alignment marks or fiducials for hybrid bonding processes, but are not limited to bonding processes alone. In the cross-sectional view 100A of FIG. 1 , a first substrate 102 has a circular alignment mark 104 and a second substrate 106 (or, e.g., a chip, etc.) has a donut-shaped alignment mark 108. When viewed from the top down 110, a low-resolution infrared camera, for example, would attempt to place the circular alignment mark 104 at the center 112 of the donut-shaped alignment mark 108. In the top-down view 100B, the donut-shaped alignment mark 108 of the second substrate is shown along with the circular alignment mark 104 of the first substrate 102. In the bottom-up view 200 of Figure 2, the connection pad area 202 of the second substrate 106 and the four donut-shaped alignment marks 108 are shown.

[0015] In diagram 300 of FIG. 3 , the second substrate 106 was bonded to the first substrate 102, and a bonding performance test was performed. The inventors discovered that voids 302 formed in the bonded surfaces in the areas of the alignment marks (i.e., at the four corners), reducing bonding performance and therefore yield. To determine the cause of the void formation, the inventors designed a new alignment mark using a cross-pattern alignment mark 402 for the first substrate and an L-shaped alignment mark 404 for the second substrate, as shown in diagram 400 of FIG. 4 . A gap or space 406 was added between the cross-pattern alignment mark 402 and the L-shaped alignment mark 404 to allow for any alignment shift due to an alignment device (e.g., a camera, a laser, etc.; generally, alignment devices have a certain resolution limit, e.g., a few microns). In some embodiments, the width 408 of the space 406 is about 5 microns to about 10 microns. In some embodiments, the width 408 is based on the resolution limit of the alignment device to prevent the appearance or existence of overlap between two alignment marks during alignment. By having non-overlapping alignment marks, misalignment can be measured and corrected or improved. In the example of FIG. 400, the alignment marks are located away from the contact pad area 410.

[0016] The inventors evaluated the new alignment mark, as shown in the diagram 400 of FIG. 4, by examining a portion of the L-shaped alignment mark 404, as shown in the isometric view 500A of FIG. 5. A first graph 500B shows surface information along the first cut line 504 of the second substrate 502 after the CMP process. Both the first copper contact 508 and the second copper contact 510 exhibit dishing (reduced height) compared to the dielectric surface material 514. The first cut line portion 512 of the L-shaped alignment mark exhibited severe dishing (a two-fold or more reduction in height) below the dielectric surface material 514 compared to the first copper contact 508 and the second copper contact 510. A second graph 500C shows surface information along the second cut line 506 of the second substrate 502 after the CMP process. Both the third copper contact 516 and the fourth copper contact 518 exhibit dishing (reduced height) compared to the dielectric surface material 514. The second cut line portion 520 of the L-shaped alignment mark exhibited severe dishing (a two-fold or more reduction in height) below the dielectric surface material 514 compared to the third copper contact 516 and the fourth copper contact 518. The inventors discovered that the severe dishing found in the alignment marks is at least partially responsible for the void formation found after the bonding process. The inventors also discovered that the large open area around the alignment mark causes a large step height 522 to form in the surface of the dielectric material between the contact pad area of ​​the second substrate 502 and the alignment mark area.

[0017] Regarding severe dishing caused by alignment marks, the inventors discovered that reducing the width 602 of the alignment mark directly impacts dishing. As shown in diagram 600 of FIG. 6 , when the width 602 is reduced to approximately 5% of the copper CD of the contact pad area 410 of the same substrate on which the alignment mark is formed, the width 602 provides a dramatic reduction in the amount of dishing resulting from the CMP process on the alignment mark. In the example of FIG. 6 , the contact pad area 410 has a CD that is approximately the same as that found in the first alignment mark 604 (a cross mark) of the first substrate. The second alignment mark 606, when aligned as shown in FIG. 6 , has a CD that is approximately the same as that found on a second substrate positioned above or below the first substrate. In some embodiments, the inventors discovered that doubling and / or tripling the size of the alignment mark facilitated positioning and alignment by a low-resolution alignment device when using reduced-width alignment marks.

[0018] In diagram 600 of FIG. 6 , the outer L-shape of the second substrate is split as shown in diagram 400 of FIG. 4 , with each split approximately maintaining (within about 5%) the CD of the copper contact. Splitting the alignment mark keeps dishing to a minimum while still allowing an alignment device to properly focus on the alignment mark. In some embodiments, the alignment mark is composed of similar portions offset from each other in both the X-direction 608 and the Y-direction 610 with a space 612 between them. In a similar manner, the cross-pattern alignment mark 402 of diagram 400 of FIG. 4 is split, with each portion reflecting the copper contact CD of the substrate on which the alignment mark resides. In other words, the copper contact CD may be different for different substrates, and the width of the alignment mark will also reflect the difference in CD, respectively, to the substrate on which the alignment mark resides. An advantage of the improved alignment mark layout is that despite differences in the widths of the alignment marks on the substrates being aligned, alignment can still occur, allowing for reduced dishing and reduced bonding voids (increased yield) on both substrates.

[0019] The inventors have also discovered that the step height difference described above affects bonding performance (dielectric surface height differences can also contribute to void formation during bonding). To further reduce void formation, the inventors have discovered that adding a dummy pattern 702 that approximately mimics (within about 5%) the CD and density of the contact pad area 410 around the alignment mark area, as shown in the top-down view 700 of FIG. 7, can also dramatically reduce void formation during bonding by reducing the step height difference of the dielectric surface of the substrate. By combining a CD-based alignment mark with a dummy pattern, as shown in the isometric view 800a of FIG. 8, the inventors have found a dramatic improvement in void reduction during the bonding process. As shown in graph 800B for the first cut line 504, the dishing of the CD-based alignment mark in the first cut line portion 512 is approximately the same as that in the contact pad area 410 (first copper contact 508 and second copper contact 510) and the dummy pattern 702 (first dummy copper contact 802), resulting in a significant reduction compared to that shown in first graph 500B of FIG. 5. As shown in graph 800C of FIG. 8 for the second cut line 506, the dishing in the second cut line portion 520 and split alignment mark portion 808 is approximately the same as that in the third copper contact 516, the fourth copper contact 518, the second dummy copper contact 804, and the third dummy copper contact 806. The additional dummy copper contacts also facilitate reducing a large step height 522 in the dielectric material surface of the substrate, further reducing void formation during bonding.

[0020] The shape and / or number of divided features are not limiting factors for obtaining the benefits of CD-based alignment marks. As used herein, a substrate may be used for a substrate comprising a chip and / or a substrate to which one or more chips may be bonded, etc. For lithography and other systems, one alignment mark may be on the substrate, and another alignment mark may be on an overlay or other object to which the substrate is aligned. FIG. 9 shows further examples of shapes that may be used for CD-based alignment marks. In the top-down view 900A of FIG. 9, a first single circle alignment mark 902 is used in conjunction with a second double circle alignment mark 904, which uses a concentric circle shape with a smaller diameter than the first single circle alignment mark 902 (resulting in alignment 906). In the top-down view 900B of FIG. 9, a first double square alignment mark 908 is used in conjunction with a second single square alignment mark 910, which has a smaller dimension than the first double square alignment mark 908 (resulting in alignment 912). In top-down view 900C of FIG. 9 , a first double-circle alignment mark 914 with a first CD is used with a second double-circle alignment mark 916 with a second CD different from the first CD and with a smaller diameter than the first double-circle alignment mark 914 (resulting in alignment 918). The techniques of the present principles are also not limited to using similar shapes for alignment (see, for example, FIGS. 4 and 6 ). In top-down view 900D of FIG. 9 , a first bar array alignment mark 920 is used with a second bar array alignment mark 922 (resulting in alignment 924). In some embodiments, the first bar array alignment mark 920 may have a first bar width 926 of about 10 μm. In some embodiments, the second bar array alignment mark 924 may have a second bar width 928 of about 10 μm. In some embodiments, the first bar width 926 may be different from the second bar width 928. The above described embodiments are not limiting as any shaped and / or divided alignment marks with similar and / or different CDs may be utilized as long as the alignment marks are concentric.

[0021] The inventors have further discovered that by leveraging CD differences for a particular alignment mark, a key-and-keyhole bonding solution can also be achieved. In some embodiments, a concentric circle layout, such as that illustrated in top-down view 900A of FIG. 9 , can be used as a key-and-keyhole alignment mark. The inventors have discovered that dielectric protrusions and dielectric recesses on opposing substrates that offset each other in size can be used to achieve key-and-keyhole alignment, resulting in a tight bond between the two substrates with high precision alignment. While the following examples utilize a concentric circle alignment mark layout, the use of concentric circles for alignment marks is not limiting, as other shapes and / or divisions can be used in the key-and-keyhole approach.

[0022] In FIG. 11 , a first substrate 1102 is shown in an isometric view 1100A with a first alignment mark 1104 including a dual concentric circle layout. The first substrate 1102 is also shown in a top-down view 1100B to better illustrate the layout. Graph 1100C shows a first cross-sectional view of a first surface portion 1112 of the first substrate 1102 at a first cutting line AA 1114. The first alignment mark 1104 is located on the first substrate 1102 in a dielectric material area where a protrusion 1106 having a height 1110 is formed from the dielectric material. In some embodiments, a first width 1108 (e.g., diameter, etc.) of the protrusion 1106 can encompass the entire first alignment mark 1104. In some embodiments, the first width 1108 can be greater than or less than the entire first alignment mark 1104. In FIG. 12 , a second substrate 1202 is shown in an isometric view 1200A with a second alignment mark 1204 including a single-circle layout. The second substrate 1202 is also shown in a top-down view 1200B to better illustrate the layout. Graph 1200C shows a second cross-sectional view of a second surface portion 1212 of the second substrate 1202 at a second cutting line BB 1214. The second alignment mark 1204 is located on the second substrate 1202 in a dielectric material area where a recess 1206 having a depth 1210 is formed from the dielectric material. In some embodiments, a second width 1208 (e.g., a diameter, etc.) of the recess 1206 can encompass the entire central area 1216 of the second alignment mark 1204. In some embodiments, the second width 1208 can be greater than or less than the central area 1216 of the second alignment mark 1204.

[0023] In diagram 1300 of FIG. 13 , the first substrate 1102 with the first alignment mark 1104 and protrusion 1106 is inverted and aligned with the second alignment mark 1204 and recess 1206. In some embodiments, the visual aspects of the first alignment mark 1104 (e.g., dual concentric circles, etc.) and the second alignment mark 1204 (e.g., a single larger circle, etc.) enable an initial, “coarse” optical alignment. The protrusion 1106 of the first alignment mark 1104 and the recess 1206 of the second alignment mark 1204 provide further physical alignment, as the protrusion 1106 and the recess 1206 are nested within each other as shown in diagram 1400 of FIG. 14 (the recess 1206 receives the protrusion 1106 and adjusts the first and second substrate alignment through walls and / or surface contacts around the protrusion 1106 and / or within the recess 1206). In some embodiments, the first width 1108 of the protrusion 1106 represents a first CD that may be based on the first substrate CD of the first substrate 1102, and the second width 1208 of the recess 1206 represents a second CD that may be based on the second substrate CD of the second substrate 1202. In some embodiments, the difference between the first CD and the second CD (approximately twice the value of the second width 1208 minus the value of the first width 1108, or delta 1302, as shown in FIG. 13 ) may be less than about 0.4 μm. The smaller the difference between the first CD and the second CD, the more accurately the first substrate 1102 will be aligned with the second substrate 1202.

[0024] In some embodiments, the difference 1402 (see FIG. 14 ) between the height 1110 of the protrusion 1106 of the first substrate 1102 and the depth 1210 of the recess 1206 of the second substrate 1202 can be less than about 0.7 nm. The smaller the difference between the height 1110 of the protrusion 1106 and the depth 1210 of the recess 1206, the closer the contact between the surface of the protrusion 1106 and the surface of the recess 1206, providing a higher bond strength between the substrates at the alignment mark location. The lock-and-key technique is not limited by the above example in that other shapes and / or divisions can be used as alignment marks, and other shapes can be used to form the protrusions and recesses. Furthermore, the first substrate 1102 and / or the second substrate 1202 can be chips or substrates to which chips are aligned. Similarly, recesses or protrusions may be formed on the chip or on the substrate, and the particular orientation shown in the examples is not limiting (e.g., a substrate with protrusions may be inverted and aligned over a substrate with recesses, or a substrate with recesses may be inverted and aligned over a substrate with protrusions, etc.).

[0025] A method 1000 for forming an alignment mark according to some embodiments is shown in FIG. 10 . Method 1000 may be used to form alignment marks in lithography apparatuses, inspection apparatuses, and / or bonding apparatuses, etc. In block 1002, a first CD-based alignment mark is formed on a first substrate. In some embodiments, the first CD-based alignment mark may be formed from copper or other metal material similar to that used on other portions of the first substrate. The use of similar metal material promotes more uniform CMP parameters (e.g., similar erosion rates, etc.) across the surface of the substrate during the CMP process. In some embodiments, one or more widths of the CD-based alignment mark will be within about 5% of the CD of a copper pad on the first substrate. The shape of the first CD-based alignment mark may be as shown above in Figures 4, 6, and 9, or may be hexagonal, octagonal, and / or any other mark shape that promotes proper alignment while meeting CD requirements (e.g., similar to Figure 6, where replicated portions of the mark are offset from each other in both the X and Y directions with a space between them).

[0026] In block 1004, a first dummy pattern is formed on the first substrate near the first CD-based alignment mark. The first dummy pattern has a CD within about 5% of the copper CD of the contact pad area of ​​the first substrate. The first dummy pattern also approximately mimics the density of the contact pad area within 5%. The first dummy pattern should be positioned around or near the first CD-based alignment mark with similar spacing used by the contact pad area of ​​the first substrate. The spacing between the first CD-based alignment mark and the dummy pattern area should also be similar to the spacing used in the contact pad area, but should not interfere with (e.g., overlap, misread, etc.) the first CD-based alignment mark. In some embodiments, the first CD-based alignment mark and the first dummy pattern reduce CMP erosion by about 20% in the area of ​​the first substrate including the first CD-based alignment mark and the first dummy pattern.

[0027] In block 1006, a second CD-based alignment mark is formed on the second substrate. In some embodiments, the second CD-based alignment mark may be formed from copper or other metal material similar to that used on other portions of the second substrate. The use of similar metal material promotes more uniform CMP parameters (e.g., similar erosion rates, etc.) across the surface of the substrate during the CMP process. In some embodiments, the width(s) of the CD-based alignment mark will be within about 5% of the CD of the copper pad on the second substrate. The shape of the second CD-based alignment mark may be as shown above in FIGS. 4, 6, and 9, or may be hexagonal, octagonal, and / or any other mark shape that promotes proper alignment while meeting CD requirements (e.g., similar to FIG. 6, where replicated portions of the mark are offset from each other in both the X and Y directions with a space between them). The CD of the second substrate may be the same as or different from the CD of the first substrate. The same is true for the CD of the first CD-based alignment mark and the CD of the second CD-based alignment mark.

[0028] In block 1008, a second dummy pattern is formed on the second substrate near the second CD-based alignment mark. The second dummy pattern has a CD within approximately 5% of the copper CD of the contact pad area of ​​the second substrate. The second dummy pattern also closely mimics the density of the contact pad area within 5%. The second dummy pattern should be positioned around or near the second CD-based alignment mark with similar spacing used by the contact pad area of ​​the second substrate. The spacing between the second CD-based alignment mark and the dummy pattern area should also be similar to the spacing used in the contact pad area, but should not interfere with (e.g., overlap, misread, etc.) the second CD-based alignment mark. The second CD-based alignment mark nests within the first CD-based alignment mark without border overlap when the second substrate overlies or underlies the first substrate, resulting in a predetermined alignment between the first and second substrates.

[0029] In some embodiments, the second CD-based alignment mark and the second dummy pattern reduce CMP erosion by about 20% in areas of the second substrate that include the second CD-based alignment mark and the second dummy pattern. In some embodiments, the second CD-based alignment mark is positioned about 5 microns to about 10 microns away from the first CD-based alignment mark to allow for an alignment shift when positioned within the first CD-based alignment mark from a top-down perspective. In other words, the outermost dimension of the second CD-based alignment mark is 5 microns or more smaller than the innermost dimension of the first CD-based alignment mark.

[0030] Embodiments according to the present principles may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented as instructions stored using one or more computer-readable media, which may be read and executed by one or more processors. A computer-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing platform or a “virtual machine” running on one or more computing platforms). For example, a computer-readable medium may include any suitable form of volatile or non-volatile memory. In some embodiments, a computer-readable medium may include a non-transitory computer-readable medium.

[0031] While the forgoing is directed to embodiments of the present principles, other and further embodiments of the present principles may be devised without departing from its basic scope.

Claims

1. 1. A method for forming an alignment mark, comprising: forming a first alignment mark on a first substrate, the first alignment mark having a first width within 5% of a critical dimension (CD) of a first copper pad on the first substrate; forming a first dummy pattern of first dummy copper pads on the first substrate around the first alignment mark, the first dummy pattern having a first dummy pattern density within 5% of a density of first copper pads on the first substrate, and the first dummy copper pads having a first dummy copper pad CD within 5% of a CD of the first copper pads on the first substrate; forming a second alignment mark on a second substrate, the second alignment mark having a second width within 5% of a critical dimension (CD) of a second copper pad on the second substrate; forming a second dummy pattern of second dummy copper pads on the second substrate around the second alignment mark, the second dummy pattern having a second dummy pattern density within 5% of a density of second copper pads on the second substrate, and the second dummy copper pads having second dummy copper pad CDs within 5% of a CD of the second copper pads on the second substrate; Including, the second alignment mark nests within the first alignment mark from a top-down perspective without boundary overlap when the second substrate overlies or underlies the first substrate, resulting in a predetermined alignment between the first substrate and the second substrate. method.

2. The method of claim 1 , wherein the first alignment mark is L-shaped and the second alignment mark is cross-shaped.

3. The method of claim 1 , wherein the first alignment mark is a first circle and the second alignment mark is a second circle of a different diameter than the first circle.

4. The method of claim 1 , wherein the first alignment mark is made up of replicated portions offset from one another in both the X and Y directions with spaces between them.

5. The method of claim 1 , wherein the first alignment mark has a recess and the second alignment mark has a protrusion, the depth of the recess being greater than the height of the protrusion.

6. The method of claim 1 used to form a lithography alignment mark, an inspection alignment mark, or a bonded alignment mark.

7. 2. The method of claim 1, wherein a CD of the first copper pad on the first substrate is different from a CD of the second copper pad on the second substrate.

8. 2. The method of claim 1, wherein the second alignment mark is positioned about 5 microns to about 10 microns away from the first alignment mark to allow for an alignment shift when located within the first alignment mark from the top-down perspective.

9. 10. The method of claim 1, wherein the first alignment mark and the first dummy pattern reduce chemical mechanical polishing (CMP) erosion in areas of the first substrate including the first alignment mark and the first dummy pattern by approximately 20%.

10. 1. A method for forming an alignment mark, comprising: forming a first alignment mark on a first substrate, the first alignment mark having a first width within 5% of a critical dimension (CD) of a first copper pad on the first substrate; forming a first dummy pattern of first dummy copper pads on the first substrate around the first alignment mark, the first dummy pattern having a first dummy pattern density within 5% of a density of first copper pads on the first substrate, and the first dummy copper pads having a first dummy copper pad CD within 5% of a CD of the first copper pads on the first substrate; forming a second alignment mark on a second substrate, the second alignment mark having a second width within 5% of a critical dimension (CD) of a second copper pad on the second substrate; forming a second dummy pattern of second dummy copper pads on the second substrate around the second alignment mark, the second dummy pattern having a second dummy pattern density within 5% of a density of second copper pads on the second substrate, and the second dummy copper pads having second dummy copper pad CDs within 5% of a CD of the second copper pads on the second substrate; Including, a CD of the first copper pad on the first substrate is different from a CD of the second copper pad on the second substrate; the second alignment mark nests within the first alignment mark from a top-down perspective without boundary overlap when the second substrate overlies or underlies the first substrate, resulting in a predetermined alignment between the first substrate and the second substrate; the second alignment mark is positioned about 5 microns to about 10 microns away from the first alignment mark to allow for alignment shift when positioned within the first alignment mark from a top-down perspective. method.

11. The method of claim 10 , wherein the first alignment mark is L-shaped and the second alignment mark is cross-shaped.

12. The method of claim 10 , wherein the first alignment mark is a first circle and the second alignment mark is a second circle of a different diameter than the first circle.

13. The method of claim 10 , wherein the first alignment mark is made up of replicated portions offset from one another in both the X and Y directions with spaces between them.

14. The method of claim 10 , wherein the first alignment mark or the second alignment mark is comprised of a plurality of concentric circles.

15. The method of claim 10 used to form a lithography alignment mark, an inspection alignment mark, or a bonded alignment mark.

16. 11. The method of claim 10, wherein the first alignment mark and the first dummy pattern reduce chemical mechanical polishing (CMP) erosion in areas of the first substrate including the first alignment mark and the first dummy pattern by about 20%.

17. 1. A non-transitory computer readable medium having stored thereon instructions that, when executed, cause performance of a method for forming alignment marks, the method comprising: forming a first alignment mark on a first substrate, the first alignment mark having a first width within 5% of a critical dimension (CD) of a first copper pad on the first substrate; forming a first dummy pattern of first dummy copper pads on the first substrate around the first alignment mark, the first dummy pattern having a first dummy pattern density within 5% of a density of first copper pads on the first substrate, and the first dummy copper pads having a first dummy copper pad CD within 5% of a CD of the first copper pads on the first substrate; forming a second alignment mark on a second substrate, the second alignment mark having a second width within 5% of a critical dimension (CD) of a second copper pad on the second substrate; forming a second dummy pattern of second dummy copper pads on the second substrate around the second alignment mark, the second dummy pattern having a second dummy pattern density within 5% of a density of second copper pads on the second substrate, and the second dummy copper pads having second dummy copper pad CDs within 5% of a CD of the second copper pads on the second substrate; Including, the second alignment mark nests within the first alignment mark from a top-down perspective without boundary overlap when the second substrate overlies or underlies the first substrate, resulting in a predetermined alignment between the first substrate and the second substrate. Non-transitory computer-readable medium.

18. 18. The non-transitory computer-readable medium of claim 17, wherein the first alignment mark is L-shaped and the second alignment mark is cross-shaped, or the first alignment mark is a first circle and the second alignment mark is a second circle of a different diameter than the first circle.

19. 18. The non-transitory computer-readable medium of claim 17, wherein the first alignment mark is comprised of replicate portions offset from one another in both the X and Y directions with spacing therebetween, or wherein a CD of the first copper pad on the first substrate is different from a CD of the second copper pad on the second substrate.

20. 18. The non-transitory computer-readable medium of claim 17, wherein the second alignment mark is positioned about 5 microns to about 10 microns away from the first alignment mark to allow for an alignment shift when located within the first alignment mark from the top-down perspective, or wherein the first alignment mark and the first dummy pattern reduce chemical-mechanical polishing (CMP) erosion by about 20% in an area of ​​the first substrate including the first alignment mark and the first dummy pattern.

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