Method for forming alignment marks

Abstract

A method for forming alignment marks utilizes pad density and critical dimension (CD). In some embodiments, the method includes forming a first alignment mark and a second alignment mark on a first substrate and a second substrate, where the alignment marks have a width within 5% of an associated CD of a copper pad on the respective substrate, and forming a first dummy pattern and a second dummy pattern around the first alignment mark and the second alignment mark. The first dummy pattern and the second dummy pattern have a dummy pattern density within 5% of a respective copper pad density of the first substrate and the second substrate and a CD within 5% of a respective copper pad CD. In some embodiments, alignment marks having protrusions and grooves of solid dielectric material on opposing substrate surfaces may further enhance adhesion.

Description

Technical Field

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

[0002] Often during the manufacture of semiconductor components, it is necessary to align the components for correct processing operations. Alignment is necessary for lithographic processes, metrology processes, and / or bonding processes and similar processes. Typically, alignment marks or symbols are used to indicate whether a cover layer or another substrate is correctly aligned. However, alignment marks are kept away from areas containing main semiconductor devices or critical lithographic areas to prevent interference with semiconductor design or layout. The inventors have observed that in some cases, due to the placement and isolation of alignment marks, the area of ​​the alignment marks inadvertently causes component manufacturing problems.

[0003] Thus, the inventors provide methods for forming high performance alignment marks that help reduce component manufacturing issues. Summary of the invention

[0004] Methods of forming high performance alignment marks for semiconductor manufacturing are provided herein.

[0005] In some embodiments, a method for forming an alignment mark may include: forming a first alignment mark on a first substrate, wherein the first alignment mark has a first width within 5% of a first critical dimension (CD) of a copper pad on the first substrate; forming a first dummy pattern of a first dummy copper pad around the first alignment mark on the first substrate, wherein the first dummy pattern has a first dummy pattern density within 5% of a first copper pad density of the first substrate and the first dummy copper pad has a first dummy copper pad DC within 5% of a first CD of the copper pad on the first substrate; forming a second alignment mark on a second substrate, wherein the second alignment mark has a second width within 5% of a second critical dimension (CD) of the copper pad on the second substrate; and forming a second dummy pattern of a second dummy copper pad around the second alignment mark on the second substrate, wherein the second dummy pattern has a second dummy pattern density within 5% of the second copper pad density of the second substrate and the second dummy copper pad has a second dummy copper pad CD within 5% of the second CD of the copper pad on the second substrate, wherein when the second substrate is overlaid on or underlaid on the first substrate, from a top-down perspective, the second alignment mark is nested within the first alignment mark without any border coverage, thereby resulting in a predetermined alignment of the first substrate with the second substrate.

[0006] In some embodiments, a method for forming an alignment mark may include: forming a first alignment mark on a first substrate, wherein the first alignment mark has a first width within 5% of a first critical dimension (CD) of a copper pad on the first substrate; forming a first dummy pattern of a first dummy copper pad around the first alignment mark on the first substrate, wherein the first dummy pattern has a first dummy pattern density within 5% of a first copper pad density of the first substrate and the first dummy copper pad has a first dummy copper pad DC within 5% of a first CD of the copper pad on the first substrate; forming a second alignment mark on a second substrate, wherein the second alignment mark has a second width within 5% of a second critical dimension (CD) of the copper pad on the second substrate; and forming a first dummy pattern of a first dummy copper pad around the first alignment mark on the second substrate. a second dummy pattern of the second dummy copper pad, wherein the second dummy pattern has a second dummy pattern density within 5% of the second copper pad density of the second substrate and the second dummy copper pad has a second dummy copper pad CD within 5% of the second CD of the copper pad on the second substrate, wherein the first CD of the copper pad on the first substrate is different from the second CD of the copper pad on the second substrate, wherein when the second substrate overlies or underlies the first substrate, in a top-down perspective, the second alignment mark is nested within the first alignment mark without any border overlap, thereby resulting in a predetermined alignment of the first substrate with the second substrate, and wherein when the second alignment mark is located within the first alignment mark in a top-down perspective, the second alignment mark is spaced apart from the first alignment mark by about 5 microns to about 10 microns to allow for alignment offset.

[0007] In some embodiments, a non-transitory computer-readable medium stores instructions thereon, which when executed, cause a method for forming an alignment mark to be executed, the method comprising: forming a first alignment mark on a first substrate, wherein the first alignment mark has a first width within 5% of a first critical dimension (CD) of a copper pad on the first substrate; forming a first dummy pattern of a first dummy copper pad around the first alignment mark on the first substrate, wherein the first dummy pattern has a first dummy pattern density within 5% of a first copper pad density of the first substrate and the first dummy copper pad has a first dummy copper pad DC within 5% of a first CD of the copper pad on the first substrate; A second alignment mark is formed on the second substrate, wherein the second alignment mark has a second width within 5% of a second critical dimension (CD) of a copper pad on the second substrate; and a second dummy pattern of a second dummy copper pad is formed around the second alignment mark on the second substrate, wherein the second dummy pattern has a second dummy pattern density within 5% of a second copper pad density of the second substrate and the second dummy copper pad has a second dummy copper pad CD within 5% of a second CD of the copper pad on the second substrate, wherein when the second substrate is overlaid on or underlaid on the first substrate, from a top-down perspective, the second alignment mark is nested within the first alignment mark without any border coverage, thereby resulting in a predetermined alignment of the first substrate with the second substrate.

[0008] Other and further embodiments are disclosed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The embodiments of the present principles briefly summarized above and discussed in more detail below can be understood by reference to the illustrative embodiments of the present principles depicted in the accompanying drawings. However, the accompanying drawings only illustrate typical embodiments of the present principles and are therefore not to be considered limiting of scope, as the present principles may allow other equally effective embodiments.

[0010] Figure 1 Depicted are cross-sectional and top-down views of alignment marks, according to some embodiments of the present principles.

[0011] Figure 2 Depicted is a bottom-up view of a chip according to some embodiments of the present principles.

[0012] Figure 3 Depicted is a bottom-up view of a bonding gap of a chip, according to some embodiments of the present principles.

[0013] Figure 4 Depicted is a top-down view of an alignment mark and contact pad area of ​​a substrate, according to some embodiments of the present principles.

[0014] Figure 5Depicted are an isometric view and diagram of a portion of a substrate having alignment marks, according to some embodiments of the present principles.

[0015] Figure 6 Alignment marks with separation lines are depicted, in accordance with some embodiments of the present principles.

[0016] Figure 7 Alignment marks having dummy patterns are depicted, according to some embodiments of the present principles.

[0017] Figure 8 Depicted are an isometric view and diagram of a portion of a substrate having alignment marks, according to some embodiments of the present principles.

[0018] Fig. 9 Depicted is a top-down view of an alignment mark, according to some embodiments of the present principles.

[0019] Fig.10 Methods for forming alignment marks according to some embodiments of the present principles are described.

[0020] Fig.11 An isometric view, a top-down view, and a diagram are depicted of alignment marks using a lock and key approach with protrusions, according to some embodiments of the present principles.

[0021] Fig.12 An isometric view, a top-down view, and a diagram are depicted of alignment marks using a lock and key approach with grooves, according to some embodiments of the present principles.

[0022] Fig.13 Depicted is a cross-sectional view of aligning a substrate having an alignment mark with a protrusion with a substrate having an alignment mark with a recess, according to some embodiments of the present principles.

[0023] Fig.14 Depicted is a cross-sectional view of a substrate having an alignment mark with a protrusion being aligned to a substrate having an alignment mark with a recess, according to some embodiments of the present principles.

[0024] For ease of understanding, the same reference numerals have been used where possible to identify the same elements common to the figures. The drawings are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. DETAILED DESCRIPTION

[0025] The method provides enhanced alignment marks for semiconductor manufacturing processes, such as bonding processes, lithography processes, and / or metrology processes, etc. In some embodiments, the alignment marks and alignment areas are based on parameters such as chip pads to significantly reduce chemical mechanical polishing (CMP) defects that affect the performance of semiconductor components throughout the manufacturing process. For example, when CMP processing is used before hybrid bonding applications, the method of the present principles can be used to change the baseline design rules. The present principles advantageously provide, for example, uniform bonding strength across the bonded chip and substrate, and eliminate any weak bonding areas to substantially improve the reliability of the packaged chip.

[0026] The inventors have found that some manufacturing problems are directly related to the reference design layout. For example, in hybrid bonding, voids are found near the reference. Current CMP processes focus on process tuning, such as using the best slurry combination and process knob tuning, such as polishing pressure and polishing time. However, the CMP process does not address the impact of the reference, and the reference design layout on the performance of the manufacturing process. In order to minimize any negative impact of the reference design layout, the inventors have found that the key CMP requirements for achieving successful hybrid bonding of both the bonding pad and the reference include: for a post-bonding annealing temperature of about 350 degrees Celsius, the depression is less than about 5nm, the minimum dielectric rounding is about less than 3nm, the dielectric surface roughness or Ra is less than about 0.5nm per 10μm×10μm surface area, and there is no blocking protrusion. The dielectric roundness around the reference area is particularly important because the area is usually isolated from the main bonding pad array, and therefore, the absence of any large dielectric portion of the contact pad will affect the bonding quality. In order to achieve the CMP parameters, the reference area layout is enhanced to produce a more uniform surface during the CMP process. In some embodiments, the fiducial area is formed so that the fiducials (alignment marks) and fiducial areas have a copper critical dimension (CD) similar to that of the chip pads (connection areas). In addition, the fiducial area density has a density similar to that of the chip pads. With close matching of CD and density (within about 5%), the CMP process will provide similar surface properties for the entire chip surface (not just the chip pad surface).

[0027] As used herein, "alignment mark" is used as a general term that includes references, etc., used to align or center one or more objects relative to each other or a standard. The alignment marks discussed herein may be used for bonding alignment, overlay alignment, metrology alignment, etc. For the sake of brevity, the alignment marks are discussed in the context of alignment marks or references used in hybrid bonding processes, but are not meant to be limited to bonding processes. Figure 1In the cross-sectional view 100A of FIG. 1 , a first substrate 102 has a circular alignment mark 104 and a second substrate 106 (or, for example, a chip, etc.) has a donut-shaped alignment mark 108. When viewed from the top down 110, for example, a low-resolution infrared camera will attempt to place the donut-shaped alignment mark 104 in 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 depicted, as well as the circular alignment mark 104 of the first substrate 102. Figure 2 In the bottom-up view 200 of FIG. 1 , a connection pad area 202 and four annular alignment marks 108 of the second substrate 106 are depicted.

[0028] exist Figure 3 In view 300 of FIG. 1 , the second substrate 106 is bonded to the first substrate 102 and a bonding performance test is performed. The inventors found that in the area of ​​the alignment marks (i.e., in the four corners), voids 302 have formed in the bonding surface, thereby reducing the bonding performance and thus the yield. In order to determine the cause of the void formation, the inventors designed new alignment marks, 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 FIG. Figure 4 400 . A gap or space 406 is added between the cross pattern alignment mark 402 and the L-shaped alignment mark 404 to allow for any alignment offset by an alignment device (e.g., a camera, a laser, etc. - typically, the alignment device has 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 actual overlap between the two alignment marks during alignment. By having non-overlapping alignment marks, misalignment can be measured and corrected or improved. In the example of view 400 , the alignment marks are spaced apart from the contact pad area 410 .

[0029] The inventors checked Figure 5 The portion of the L-shaped alignment mark 404 depicted in the isometric view 500A is used to evaluate the Figure 44. The first graph 500B depicts surface information along the first cut line 504 of the second substrate 502 after the CMP process. The first copper contact 508 and the second copper contact 510 both exhibit recesses (reduced heights) compared to the dielectric surface material 514. The first cut line portion 512 of the L-shaped alignment mark exhibits severe recesses (double or more reduction in height) below the dielectric surface material 514 compared to the first copper contact 508 and the second copper contact 510. The second graph 500C depicts surface information along the second cut line 506 of the second substrate 502 after the CMP process. The third copper contact 516 and the fourth copper contact 518 both exhibit recesses (reduced heights) compared to the dielectric surface material 514. The second cut line portion 520 of the L-shaped alignment mark exhibits severe recesses (double 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 have found that the severe depressions found in the alignment marks are at least partially responsible for the void formation found after the bonding process. The inventors have also found that the large open areas around the alignment marks result in large step heights 522 being formed in the surface of the dielectric material between the contact pad area and the alignment mark area of ​​the second substrate 502.

[0030] With regard to severe dishing caused by alignment marks, the inventors have found that reducing the width 602 of the alignment marks directly affects the dishing. Figure 6 As depicted in view 600 of FIG. 1 , width 602 provides a significant reduction in the amount of dishing that occurs from the CMP process on the alignment mark if width 602 is reduced to approximately 5% of the copper CD of contact pad region 410 of the same substrate on which the alignment mark is formed. Figure 6 In the example of FIG. 4 , the contact pad region 410 has a CD that is substantially the same as the CD found in the first alignment mark 604 (cross-shaped mark) of the first substrate. Figure 6 When aligned as shown, the second alignment mark 606 has a CD that is substantially the same as a CD found on a second substrate located above or below the first substrate. In some embodiments, the inventors have discovered that when reduced width alignment marks are used, doubling and / or tripling portions of the alignment mark facilitates allowing positioning and alignment of lower resolution alignment equipment.

[0031] exist Figure 6 In view 600, as Figure 4The outer L-shape of the second substrate illustrated in view 400 of has been separated, wherein each separation maintains approximately the CD of the copper contact (within approximately 5%). The separation of the alignment marks keeps the recess to a minimum while still allowing the alignment equipment to focus correctly on the alignment marks. In some embodiments, the alignment marks are composed of similar portions offset from each other in both the X-direction 608 and the Y-direction 610 with spaces 612 between the similar portions. In a similar manner, Figure 4 The cross pattern alignment marks 402 of view 400 are separated, where each portion reflects 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 relative to the substrate on which the alignment mark resides. The advantage of the enhanced alignment mark layout is that alignment can be performed despite the difference in width of the alignment marks on the aligned substrates, thereby allowing for reduced dishing on both substrates and reduced bond voids (increased yield).

[0032] The inventors have also discovered that the step height differences described above affect bonding performance (differences in dielectric surface height can also lead to void formation during bonding). To further reduce void formation, the inventors have discovered that adding a dummy pattern 702 (e.g., Figure 7 700) can also significantly reduce void formation during bonding by reducing step height differences in the dielectric surface of the substrate. Figure 8 The inventors have found significant improvements in void reduction during the bonding process by using the CD-based alignment mark and dummy pattern depicted in the isometric view 800a of FIG. 800B of FIG. 804. As depicted in the diagram 800B of the first cut line 504, the recess of the CD-based alignment mark at the first cut line portion 512 is substantially the same as the contact pad area 410 (the first copper contact 508 and the second copper contact 510) and the dummy pattern 702 (the first dummy copper contact 802), thereby being consistent with the bonding process. Figure 5 As shown in the first graph 500B, the first cut line 506 is substantially reduced. Figure 8 As depicted in graph 800C of FIG. 80A , the recesses at the second scribe line portion 520 and the separated alignment mark portion 808 are substantially the same as 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 the large step height 522 of the dielectric material surface of the substrate, thereby further reducing void formation during bonding.

[0033] The shape and / or number of the separating features are not limiting factors for obtaining the advantages of CD-based alignment marks. As used herein, a substrate may be a substrate containing a chip and / or a substrate to which one or more chips may be bonded, etc. In the case of lithography and other systems, one alignment mark may be on the substrate and another alignment mark may be on a cover layer or other object to which the substrate is aligned. Fig. 9 Further examples of shapes that can be used for CD-based alignment marks are depicted. Fig. 9 In the top-down view 900A of , a first single circular alignment mark 902 is used in conjunction with a second double circular alignment mark 904 (with resulting alignment 906), the second double circular alignment mark 904 using a concentric circle shape having a smaller diameter than the first single circular alignment mark 902. Fig. 9 In the top-down view 900B of FIG. 1 , a first double square alignment mark 908 is used in conjunction with a second single square alignment mark 910 (with a resulting alignment 912 ), the second single square alignment mark 910 having a smaller size than the first double square alignment mark 908 . Fig. 9 In the top-down view 900C of FIG. 1 , a first double circular alignment mark 914 having a first CD is used in conjunction with a second double circular alignment mark 916 (with resulting alignment 918), the first double circular alignment mark 914 having a first CD, and the second double circular alignment mark 916 having a second CD different from the first CD and a smaller diameter than the first double circular alignment mark 914. The techniques of the present principles are also not limited to using similar shapes for alignment (e.g., see Figure 4 and Figure 6 ).exist Fig. 9 900D, a first stripe array alignment mark 920 is used in conjunction with a second stripe array alignment mark 922 (with resulting alignment 924). In some embodiments, the first stripe array alignment mark 920 may have a first stripe width 926 of approximately 10 μm. In some embodiments, the second stripe array alignment mark 924 may have a second stripe width 928 of approximately 10 μm. In some embodiments, the first stripe width 926 may be different from the second stripe width 928. The embodiments described above are not meant to be limiting, as any shapes and / or separations of alignment marks having similar CDs and / or different CDs may be utilized, as long as the alignment marks are concentric.

[0034] The inventors have further discovered that by utilizing the CD differences of specific alignment marks, a lock-and-key bonding solution can also be achieved. Fig. 9The concentric circle layout described in the top-down view 900A of FIG. 1 can be used as a lock and key alignment mark. The inventors have discovered that dielectric protrusions and dielectric grooves on opposing substrates that offset each other in magnitude can be used to achieve lock and key alignment, resulting in tight adhesion between two substrates aligned with high precision. Although the following examples utilize a concentric circle alignment mark layout, the use of concentric circles for alignment marks is not meant to be limiting, as other shapes and / or separations can be used in the lock and key method.

[0035] exist Fig.11 , the first substrate 1102 is depicted in an isometric view 1100A as having a first alignment mark 1104 including a dual concentric circle layout. The first substrate 1102 is also depicted in a top-down view 1100B to better illustrate the layout. Diagram 1100C depicts a first cross-sectional view of a first surface portion 1112 of the first substrate 1102 at a first cut line AA 1114. The first alignment mark 1104 is positioned on the first substrate 1102 in a dielectric material region in which a protrusion 1106 having a height 1110 has been formed from the dielectric material. In some embodiments, a first width 1108 (e.g., a diameter, etc.) of the protrusion 1106 may encompass the entirety of the first alignment mark 1104. In some embodiments, the first width 1108 may be greater than or less than the entirety of the first alignment mark 1104. Fig.12 12, the second substrate 1202 is depicted in an isometric view 1200A as having a second alignment mark 1204 including a single circular layout. The second substrate 1202 is also depicted in a top-down view 1200B to better illustrate the layout. Diagram 1200C depicts a second cross-sectional view of a second surface portion 1212 of the second substrate 1202 at a second cut line BB 1214. The second alignment mark 1204 is positioned on the second substrate 1202 in a dielectric material region in which a groove 1206 having a depth 1210 has been formed of the dielectric material. In some embodiments, a second width 1208 (e.g., diameter, etc.) of the groove 1206 may encompass the entirety of a central region 1216 of the second alignment mark 1204. In some embodiments, the second width 1208 may be larger or smaller than the central region 1216 of the second alignment mark 1204.

[0036] exist Fig.13 In view 1300 of FIG. 1 , the first substrate 1102 having the first alignment mark 1104 and the protrusion 1106 is flipped over and aligned with the second alignment mark 1204 and the groove 1206. In some embodiments, the visual aspects of the first alignment mark 1104 (e.g., dual concentric circles, etc.) and the visual aspects of the second alignment mark 1204 (e.g., a single larger circle, etc.) allow for an initial “rough” optical alignment. As shown in FIG. Fig.14As depicted in view 1400 of FIG. 14A , the protrusion 1106 of the first alignment mark 1104 and the recess 1206 of the second alignment mark 1204 provide further physical alignment when the protrusion 1106 and the recess 1206 are nested together (the recess 1206 receives the protrusion 1106 and adjusts the first substrate alignment and the second substrate alignment by contacting the walls and / or surfaces around the protrusion 1106 and / or within the recess 1206). In some embodiments, the first width 1108 of the protrusion 1106 indicates 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 indicates 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 (the value of the second width 1208 minus the value of the first width 1108 or as Fig.13 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.

[0037] In some embodiments, the difference 1402 (see FIG. 1402 ) 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 is Fig.14 ) may be less than about 0.7nm. The smaller the difference between the height 1110 of the protrusion 1106 and the depth 1210 of the groove 1206, the tighter the contact between the surface of the protrusion 1106 and the surface of the groove 1206 will be, thereby providing a higher bonding strength between the substrates at the alignment mark position. The lock and key method is not limited to the above examples, because other shapes and / or separations can be used as alignment marks, and other shapes can also be used to form protrusions and grooves. In addition, the first substrate 1102 and / or the second substrate 1202 can be a chip or a substrate on which a chip is aligned. Similarly, a groove or a protrusion can be formed on a chip or on a substrate, and the specific orientation depicted in the example does not mean a limitation (a substrate with a protrusion can be flipped and aligned on a substrate with a groove, or a substrate with a groove can be flipped and aligned on a substrate with a protrusion, etc.).

[0038] exist Fig.10A method 1000 for forming an alignment mark according to some embodiments is depicted in . The method 1000 can be used to form an alignment mark in a lithography device, an inspection device, and / or a bonding device, etc. In box 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 of copper or other metal materials similar to materials used on other portions of the first substrate. The use of similar metal materials promotes more uniform CMP parameters (e.g., similar corrosion rates, etc.) across the substrate surface during the CMP process. In some embodiments, one or more widths of the CD-based alignment mark will be within approximately 5% of the CD of the copper pad on the first substrate. The shape of the first CD-based alignment mark may be as described above in Figure 4 , Figure 6 and Fig. 9 , or may be hexagonal, octagonal, and / or any other marking shape that facilitates proper alignment while meeting CD requirements (e.g., Figure 6 Similarly, where the repeating portions of a mark are offset from each other in both the X-direction and the Y-direction, there are spaces between the repeating portions).

[0039] 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 approximately 5% of the copper CD of the contact pad area of ​​the first substrate. The first dummy pattern also approximately simulates within 5% of the density of the contact pad area. The first dummy pattern should be placed around or near the first CD-based alignment mark used by the contact pad area of ​​the first substrate with similar spacing. 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 not interfere with (e.g., cover, misread, etc.) the first CD alignment mark. In some embodiments, the first CD-based alignment mark and the first dummy pattern reduce CMP corrosion in the area of ​​the first substrate containing the first CD-based alignment mark and the first dummy pattern by approximately 20%.

[0040] 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 of copper or other metal material similar to that used on other portions of the second substrate. Using similar metal materials promotes more uniform CMP parameters (e.g., similar etch rates, etc.) across the substrate surface during the CMP process. In some embodiments, one or more widths of the CD-based alignment mark will be within approximately 5% of the CD of the copper pad on the second substrate. The shape of the second CD-based alignment mark may be as described above in Figure 4 , Figure 6 and Fig. 9, or may be hexagonal, octagonal, and / or any other marking shape that facilitates proper alignment while meeting CD requirements (e.g., Figure 6 Similarly, where the repeating portions of the mark are offset from each other in both the X-direction and the Y-direction with spaces between the repeating portions). The CD of the second substrate can 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.

[0041] 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 roughly simulates within 5% of the density of the contact pad area. The second dummy pattern should be placed around or near the second CD-based alignment mark used by the contact pad area of ​​the second substrate with similar spacing. 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 not interfere with (e.g., overlap, misread, etc.) the second CD-based alignment mark. When the second substrate overlies or underlies the first substrate, the second CD-based alignment mark is nested within the first CD-based alignment mark without any border overlap, thereby resulting in a predetermined alignment of the first substrate with the second substrate.

[0042] In some embodiments, the second CD-based alignment mark and the second dummy pattern reduce CMP erosion in the area of ​​the second substrate containing the second CD-based alignment mark and the second dummy pattern by about 20%. In some embodiments, when the second CD-based alignment mark is positioned within the first alignment mark in a top-down perspective, the second CD-based alignment mark is spaced apart from the first CD-based alignment mark by about 5 microns to about 10 microns to allow for alignment offset. 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.

[0043] Embodiments according to the present principles may be implemented in hardware, firmware, software, or any combination of the above. 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. Computer-readable media may include any mechanism for storing or transmitting information in a machine-readable form (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-transient computer-readable medium.

[0044] While the foregoing is directed to embodiments of the present principles, other and further embodiments of the present principles may be devised without departing from the basic scope thereof.

Claims

1. A method for forming an alignment mark, comprising the following steps: forming a first alignment mark on a first substrate, wherein the first alignment mark has a first width within 5% of a first critical dimension (CD) of a copper pad on the first substrate; forming a first dummy pattern of a first dummy copper pad around the first alignment mark on the first substrate, wherein the first dummy pattern has a first dummy pattern density within 5% of a first copper pad density of the first substrate and the first dummy copper pad has a first dummy copper pad CD within 5% of the first CD of a copper pad on the first substrate; forming a second alignment mark on a second substrate, wherein the second alignment mark has a second width within 5% of a second critical dimension (CD) of a copper pad on the second substrate; and forming a second dummy pattern of a second dummy copper pad around the second alignment mark on the second substrate, wherein the second dummy pattern has a second dummy pattern density within 5% of a second copper pad density of the second substrate and the second dummy copper pad has a second dummy copper pad CD within 5% of the second CD of the copper pad on the second substrate, When the second substrate overlies or underlies the first substrate, from a top-down perspective, the second alignment mark is nested within the first alignment mark without any border coverage, thereby resulting in a predetermined alignment between the first substrate and the second substrate. 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 having a diameter different from that of the first circle. 4 . The method of claim 1 , wherein the first alignment mark is composed of repeated portions offset from each other in both the X direction and the Y direction with spaces therebetween. 5 . The method of claim 1 , wherein the first alignment mark has a groove and the second alignment mark has a protrusion, and wherein a depth of the groove is greater than a height of the protrusion.

6. The method of claim 1 for forming a lithographic alignment mark, an inspection alignment mark, or a bonding alignment mark.

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

8. The method of claim 1, wherein when the second alignment mark is positioned within the first alignment mark in the top-down viewing angle, the second alignment mark is spaced apart from the first alignment mark by about 5 microns to about 10 microns to allow for alignment offset.

9. The method of claim 1, wherein the first alignment mark and the first dummy pattern reduce chemical mechanical polishing (CMP) erosion by about 20% in a region of the first substrate containing the first alignment mark and the first dummy pattern.

10. A method for forming an alignment mark, comprising the following steps: forming a first alignment mark on a first substrate, wherein the first alignment mark has a first width within 5% of a first critical dimension (CD) of a copper pad on the first substrate; forming a first dummy pattern of a first dummy copper pad around the first alignment mark on the first substrate, wherein the first dummy pattern has a first dummy pattern density within 5% of a first copper pad density of the first substrate and the first dummy copper pad has a first dummy copper pad CD within 5% of the first CD of a copper pad on the first substrate; forming a second alignment mark on a second substrate, wherein the second alignment mark has a second width within 5% of a second critical dimension (CD) of a copper pad on the second substrate; and forming a second dummy pattern of a second dummy copper pad around the second alignment mark on the second substrate, wherein the second dummy pattern has a second dummy pattern density within 5% of a second copper pad density of the second substrate and the second dummy copper pad has a second dummy copper pad CD within 5% of the second CD of the copper pad on the second substrate, wherein the first CD of the copper pad on the first substrate is different from the second CD of the copper pad on the second substrate, wherein when the second substrate overlies or underlies the first substrate, from a top-down perspective, the second alignment mark is nested within the first alignment mark without any border overlap, thereby resulting in a predetermined alignment of the first substrate with the second substrate, and Wherein when the second alignment mark is positioned within the first alignment mark in a top-down perspective, the second alignment mark is spaced apart from the first alignment mark by about 5 microns to about 10 microns to allow for alignment offset. 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 having a diameter different from that of the first circle. 13 . The method of claim 10 , wherein the first alignment mark is composed of repeated portions offset from each other in both the X direction and the Y direction with spaces therebetween.

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

15. The method of claim 10 for forming a lithographic alignment mark, an inspection alignment mark, or a bonding alignment mark.

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

17. A non-transitory computer readable medium having instructions stored thereon, wherein when the instructions are executed, a method for forming an alignment mark is executed, the method comprising the following steps: forming a first alignment mark on a first substrate, wherein the first alignment mark has a first width within 5% of a first critical dimension (CD) of a copper pad on the first substrate; forming a first dummy pattern of a first dummy copper pad around the first alignment mark on the first substrate, wherein the first dummy pattern has a first dummy pattern density within 5% of a first copper pad density of the first substrate and the first dummy copper pad has a first dummy copper pad CD within 5% of the first CD of a copper pad on the first substrate; forming a second alignment mark on a second substrate, wherein the second alignment mark has a second width within 5% of a second critical dimension (CD) of a copper pad on the second substrate; and forming a second dummy pattern of a second dummy copper pad around the second alignment mark on the second substrate, wherein the second dummy pattern has a second dummy pattern density within 5% of a second copper pad density of the second substrate and the second dummy copper pad has a second dummy copper pad CD within 5% of the second CD of the copper pad on the second substrate, When the second substrate overlies or underlies the first substrate, from a top-down perspective, the second alignment mark is nested within the first alignment mark without any border coverage, thereby resulting in a predetermined alignment between the first substrate and the second substrate.

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

19. The non-transitory computer readable medium of claim 17, wherein the first alignment mark is composed of repeated portions offset from each other in both the X direction and the Y direction with spaces therebetween, or wherein the first CD of the copper pad on the first substrate is different from the second CD of the copper pad on the second substrate.

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

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