CMP polishing pad with uniform window

Abstract

To provide a polishing pad with a window that provides good signal for sensing while also managing problems (e.g. defects, window deflection, changing hydrodynamics, deflection, fluid transport, etc.) that can arise from inserting a window into a polishing pad.SOLUTION: A polishing pad 10 useful in chemical mechanical polishing comprises a polishing portion having an upper polishing surface 13 and comprising a polishing material, an opening through the polishing pad, and a transparent window 14 within the opening in the polishing pad, the transparent window being secured to the polishing pad and being transparent to at least one of magnetic and optical signals, the transparent window having a thickness and a top surface having a plurality of elements separated by interconnected recesses to provide a pattern in the top surface that includes recesses for improved deflection into a cavity in the polishing pad during polishing.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates generally to the field of polishing pads for chemical mechanical polishing, and more particularly to a chemical mechanical polishing pad having an abrasive structure useful for chemical mechanical polishing of magnetic, optical, and semiconductor substrates, including front end of line (FEOL) or back end of line (BEOL) processing of memory and logic integrated circuits. [Background technology]

[0002] In the fabrication of integrated circuits and other electronic devices, multiple layers of conductive, semiconductive, and insulating materials are deposited on and partially or selectively removed from the surface of a semiconductor wafer. Thin layers of conductive, semiconductive, and insulating materials can be deposited using several deposition techniques. Common deposition techniques in modern wafer processing include physical vapor deposition (PVD), also known as sputtering, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and electrochemical deposition (ECD), among others. Common removal techniques include wet and dry etching, isotropic and anisotropic etching, among others.

[0003] As layers of material are sequentially deposited and removed, the wafer's topography (i.e., top surface) becomes uneven or non-planar. Subsequent semiconductor processing (e.g., photolithography, metallization, etc.) requires the wafer's surface to be flat, so the wafer must be planarized. Planarization is useful for removing undesirable surface topography and surface defects, such as rough surfaces, agglomerated material, crystal lattice damage, scratches, and contaminated layers or materials. Additionally, in damascene processes, material is deposited to fill recessed areas formed by patterned etching, such as trenches and vias, but the fill step can be imprecise, and overfilling the recess is preferred over underfilling it. Therefore, material outside the recess must be removed.

[0004] Chemical mechanical planarization (CMP) is a common technique used to planarize or polish workpieces, such as semiconductor wafers, and remove excess material during damascene, front-end (FEOL), or back-end (BEOL) processes. In conventional CMP, a wafer carrier or polishing head is attached to a carrier assembly. The polishing head holds the wafer and positions it in contact with the polishing surface of a polishing pad mounted on a table or platen within the CMP apparatus. The carrier assembly provides controllable pressure between the wafer and the polishing pad. Simultaneously, a slurry or other abrasive is dispensed onto the polishing pad and drawn into the gap between the wafer and the polishing layer. To perform the polishing, the polishing pad and wafer typically rotate relative to one another. As the polishing pad rotates beneath the wafer, the wafer typically traverses an annular polishing track or polishing region, with the wafer's surface directly facing the polishing layer. The wafer surface is polished and made flat by the chemical-mechanical action of the polishing surface and the abrasive (eg, slurry) on the surface.

[0005] Precise control of various aspects (e.g., layer thickness) on the substrate being polished can be desirable. Therefore, various methods have been proposed for detecting when polishing has been completed to a desired level. Because polishing pads are often made of opaque materials, a transparent window is inserted into the polishing pad. This allows for an optical detection system in which a light source directs electromagnetic radiation (e.g., light of a desired wavelength) toward the substrate through the transparent window, and a sensor detects the electromagnetic radiation (e.g., light) reflected from the wafer and returning through the window. Various window designs have been proposed. See, for example, U.S. Pat. Nos. 7,258,602, 8,475,228, 7,429,207, 9,475,168, 7,621,798, and 5,605,760, as well as JP 2006021290. There remains a need for a pad design with a window that provides a good signal for sensing while also addressing issues that can arise from inserting a window into a polishing pad (e.g., defects, window deflection, changes in fluid dynamics, deflection, fluid transport, etc.). Summary of the Invention

[0006] Disclosed herein is a polishing pad having an upper polishing surface, a bottom layer for attachment to a platen, and a polishing material, the upper polishing surface including a groove; an opening through the polishing pad; and a transparent window within the opening in the polishing pad, the transparent window being flexible and having a thickness measured from the bottom of the transparent window to the upper polishing surface of the transparent window, the transparent window being secured to the polishing pad in a spaced-apart relationship from the platen to form a cavity, the transparent window transmitting at least one of magnetic and optical signals; the transparent window having a plurality of protruding elements filling a periphery and a center of the transparent window, the tops of the plurality of protruding elements representing the upper polishing surface of the transparent window, the protruding elements having an initial height of at least 30 percent of the thickness of the transparent window, and the protruding elements protruding from the upper surface. A polishing pad useful in chemical mechanical polishing of semiconductor substrates, optical substrates, or magnetic substrates, comprising: a transparent window coplanar with an upper polishing surface separated by interconnected recesses extending to the periphery of the transparent window to provide an element pattern, most of the recesses being partially or completely misaligned with the grooves in the upper polishing surface; the protruding element pattern allowing bending of the transparent window about multiple axes about which the transparent window bends into the cavity, at least two of the axes being non-parallel to or with a central protruding element; the central protruding element surrounded by one or more recesses that bend downward into the cavity together with the central protruding element, the central protruding element having a width less than half the longest dimension of the transparent window to reduce contact pressure with the substrate during polishing.

[0007] "Uniform" with respect to a window means that the pattern is repeated across the top surface of the window and that the pattern is the same or similar in both the x and y directions, or that the pattern has point symmetry or substantial point symmetry. Substantial point symmetry means that there may be small amounts of offset from symmetry, for example, (1) the center point of the window may be offset by an amount of less than 10%, less than 5%, less than 2%, or less than 1% from the center point that would provide point symmetry for the window, based on the largest window dimension (e.g., height, width, diameter), and / or (2) the spacing between elements (e.g., recess width) may vary by up to 25%, up to 10%, or up to 5%, and / or (3) the dimensions of the elements may be slightly non-uniform, for example, feature dimensions such as radius, length, or width may vary by up to 25%, up to 20%, up to 10%, up to 5%, or up to 2% from one feature to another.

[0008] Also disclosed is a polishing method using such a polishing pad. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a top view of a portion of a prior art polishing pad having a planar window insert. [Figure 1B] FIG. 1B is a cross-sectional view taken along plane 1B-1B of FIG. 1A. [Figure 2] 2 is a cross-sectional view of a prior art polishing pad similar to FIG. 1, illustrating non-uniform deformation of the pad under load. [Figure 3A] FIG. 1 is a top view of a polishing pad including a window with a uniform pattern of interconnected recesses. [Figure 3B] FIG. 3B is a cross-sectional view of the pad of 3A taken along plane 3B-3B. [Figure 4A] FIG. 10 is a top view of a rectangular window having elements separated by interconnected recesses. [Figure 4B] FIG. 1 is a side view of a rectangular window having elements separated by interconnected recesses. [Figure 5A]FIG. 10 is a top view of a circular window having elements separated by interconnected recesses. [Figure 5B] FIG. 1 is a side view of a circular window having elements separated by interconnected recesses. [Figure 6] FIG. 1 is a top view of a circular window having closed curved recesses (circles) interconnected with recesses extending towards the periphery of the window. [Figure 7] FIG. 1 is a top view of an oval window having closed curved recesses (ovals) interconnected with recesses extending towards the periphery of the window. [Figure 8] FIG. 1 is a top view of a circular window with concentric recesses interconnected by grid lines. [Figure 9] FIG. 1 is a top view of a circular window having a uniform pattern of small elements of substantially uniform size separated by smaller recesses surrounded by larger elements and recesses around the periphery of the window. [Figure 10A] FIG. 10 shows a comparative window design with a non-uniform pattern. [Figure 10B] FIG. 10B is a cross-sectional view of the pad of 10A taken along plane 10B-10B. DETAILED DESCRIPTION OF THE INVENTION

[0010] The transparent window disclosed herein is useful for CMP polishing pads useful in chemical mechanical polishing of semiconductor, optical, or magnetic substrates. Prior to the present invention, those skilled in the art believed that the transparent window should be rigid to avoid problems with the pad becoming convex or concave. Previous solutions to these problems included attempts to make transparent polyurethane materials creep-resistant and designs that allow for pressure relief. Applicants have discovered that protruding elements separated by a series of recesses can increase the window's compliance without sacrificing adequate signal strength for endpoint detection.

[0011] The polishing pad includes a polishing portion having an upper polishing surface and a bottom layer for attaching a polishing material, such as a porous polyurethane polishing pad, to a circular stainless steel platen. The upper polishing surface includes grooves, such as circular, spider web, xy Cartesian, spiral, or other known groove patterns. A transparent window is secured within the opening in the polishing pad. The window can be cast and skived or cast in place and secured to the polishing pad using adhesives or other known means for securing a polymer window to the polymer pad material.

[0012] The transparent window has a thickness measured from the bottom of the transparent window to the upper polishing surface of the transparent window. The transparent window is fixed to the polishing pad while being spaced apart from the platen so that the transparent window forms a cavity. The window transmits at least one of magnetic and optical signals. Typically, the window transmits light having a wavelength range useful for determining the polishing endpoint. The cavity allows the transparent window to flex downward to reduce force against the substrate.

[0013] The transparent window has a plurality of protruding elements that fill the periphery and center of the transparent window. The tops of the protruding elements represent the upper polishing surface of the transparent window. The upper polishing surface of the window is aligned with the upper polishing surface of the polishing pad. The protruding elements have an initial height of at least 30% of the thickness of the transparent window. For thicker windows, the protruding elements have an initial height of at least 50% of the thickness of the transparent window. This height represents the height from the bottom of the recesses to the top surface of the protruding elements. The protruding elements are flush with the upper polishing surface, separated by interconnected recesses that extend to the periphery of the transparent window. If there is a solid backing behind the window, the recesses will substantially increase the pressure against the substrate. The recesses combine to provide a protruding element pattern on the upper surface, with the majority of the recesses being partially or completely misaligned with the grooves in the upper polishing surface. Typically, at least 80% of the recesses are partially or completely misaligned with the grooves in the upper polishing surface. In some cases, all of the recesses are partially or completely misaligned with the grooves in the upper polishing surface.

[0014] In a first embodiment, the protruding element pattern allows bending about multiple axes about which the transparent window bends into the cavity, at least two of the axes being non-parallel. Examples of non-parallel bending include bending along the x-axis and bending on the y-axis. Another example of non-parallel bending is the three bending axes formed by a hexagonal, closely packed arrangement of the protruding elements. Bending along multiple axes helps reduce contact pressure with the substrate during polishing.

[0015] In a second embodiment, a central protruding element surrounded by one or more recesses bends downward into the cavity. To facilitate efficient bending, the central protruding element has a width less than half the longest dimension of the transparent window. This serves to reduce contact pressure with the substrate during polishing. In more complex recess patterns, the central portion that bends into the cavity can bend along two or more non-parallel axes.

[0016] 1A and 1B show a prior art pad 1 having a window 4. Grooves 2 may be provided in the planar surface 3 of the polishing portion 5. The polishing portion may be a subpad or a separate layer on a base pad 6.

[0017] The polishing pads disclosed herein can provide certain advantages. Specifically, the pads disclosed herein can reduce problems associated with deflection deformation associated with windows in the pad and problems associated with fluid management around the windows. Deflection problems can arise because the window material and the polishing portion of the pad material are different (e.g., have different moduli of elasticity). The response of these materials to the load placed on the pad during polishing can lead to uneven deflection. For example, a polishing pad may have a combined Young's modulus E of about 0.15 to 0.2 GPa for the base pad and polishing layer, while the inert transparent window material may have a Young's modulus of about 0.9 to 1 GPa. For example, Figures 1A and 1B show a prior art pad 1 having a planar window 4, a polishing portion 5, and an underlayer 6. As shown in Figure 2 (not to scale), which illustrates the deflection of a simple planar window 4 under stress due to the often more flexible material of the polishing portion 5 of the pad, the window 4 may protrude above the surface of the adjacent polishing material 5 during polishing. This can lead to a gap, indicated by dimension (a), in the area adjacent to the window, where good contact between the polishing material and the substrate being polished is not achieved, potentially trapping slurry and particles and causing scratches on the substrate. Gap "a" represents the height between the top of window 4 and polishing portion 5. During polishing, subpad 6 partially alleviates gap "a," but this gap can represent a serious problem during polishing. Additionally, during pad conditioning (which may involve polishing the surface of the pad), differential wear can occur on the window surface, which can result in signal drift due to changes in window thickness and / or premature pad failure due to window thinning and potential perforation. Additionally, the surface of the polishing surface and windows that are flat or recessed from the surface of the polishing surface each present fluid management challenges in that slurry and polishing debris can collect on the window, especially at the periphery. This accumulation of slurry and polishing debris can create scratches and interfere with light transmission and the resulting optical detection of the polishing endpoint.

[0018] Previous proposals have typically addressed only the deflection problem or only the fluid management problem.

[0019] The pads disclosed herein, having windows with interconnected recesses that provide a uniform pattern, can increase the compliance of the window without having to change the window material, thereby reducing the contact pressure of the window. Additionally, the recesses in the window of the pads disclosed herein can facilitate fluid flow and avoid the accumulation of slurry and polishing by-products in the window area and adjacent areas, which can cause scratches and interfere with the endpoint optical signal.

[0020] As shown in FIGS. 3A and 3B, the polishing pad 10 disclosed herein has a polishing portion 15. The polishing portion 15 is a top portion having an upper polishing surface 13 with a groove 12 therein. While FIG. 3 shows the groove 12 ending before the edge of the window 14, it is also contemplated that the groove 12 may continue to the edge of the window 14. Advantageously, the groove 12 extends to the window 14 to provide a more consistent fluid flow over the polishing pad 14. The grooves on the pad can be aligned with the recesses in the window. Alternatively, the grooves on the pad can be misaligned or partially aligned with the recesses in the window. Typically, at least about 80% of the grooves 12 are not aligned with the grooves on the polishing pad 10. The polishing pad 10 can also have an underlayer 16 (which may be a base pad), as shown in FIG. 3B. The window 14 is secured within a cavity 17 in the pad 10, allowing a signal used for endpoint detection to pass through the pad to the substrate and be reflected. More importantly, however, the cavity 17 below the bottom of the window 14 allows the window 14 to bend, reducing contact stress between the window 14 and a substrate, such as a semiconductor wafer, during polishing. The window 14 has elements 19 separated by recesses 18, as shown in FIG. 3B, a cross-sectional view of the window 14 from a to b. The recesses 18 increase the resulting localized contact with the substrate during polishing, while the bending of the window 14 into the cavity 17 during polishing significantly reduces contact pressure during polishing. The upper surface of the elements 19 can be flush with the upper polishing surface 13 or slightly concave. Because the polishing pad and substrate rotate during polishing, the x-axis can be parallel to the radius of the polishing pad, perpendicular to the radius of the polishing pad, or at any angle between these angles. However, typically, the x-axis is parallel to and aligned with the radius of the polishing pad.

[0021] Various examples of windows that may be used in the pads disclosed herein are shown in Figures 4A, 4B, 5A, 5B, 6, 7, 8, and 9. The windows have recesses and elements that form a uniform pattern. For example, the recesses can be uniformly spaced and uniformly sized around the elements. The elements can be of uniform size and spacing. They can be uniformly sized and spaced in the x and y coordinates.

[0022] 4A and 4B show a rectangular window 101 having an upper surface with an interconnected array of recesses 102. These recesses 102 have a width measured between rectangular protrusions 103 and a depth measured from the top of the rectangular protrusions 103 to the lower surface 105 between the recesses 102. This forms a regular, uniform array of rectangular protrusions (also called protruding elements) 103, which may be the window's contact surface with the article to be polished. The upper surfaces of the protrusions 103 may be flush with the upper surface of the polishing pad. The area of ​​the portion of the protruding surface can be adjusted by increasing or decreasing the recess width and / or recess pitch (i.e., the center-to-center distance between recesses or elements). This allows for easy adjustment of the window's transmittance to correspond to the spot size of a sensor projecting light through the window. Stiffness can also be easily adjusted by varying the depth of the recess array 102. The width and depth of the recesses can be the same across the entire window, or can vary, provided the change is uniform. FIGS. 4A and 4B illustrate the use of a regular, square array of recesses. However, various other recess array patterns and element shapes can be used, including, but not limited to, hexagonal recess arrays resulting in circular, triangular, or hexagonal protruding cross sections, or combinations of different pattern sizes or overlays, provided the resulting recess array facilitates bending along at least two non-parallel axes. The recess array has point symmetry about the center 107. For purposes of this specification, point symmetry refers to all points of the protruding elements 103 and recesses 102 that are in the same position after a 180-degree rotation about a vertical axis. In this example, all points in the x and y coordinates have point symmetry about the center 107. These interconnected recesses facilitate bending along recesses parallel to the x-axis xx, bending along the y-axis recess yy, and bending along recesses with axes parallel to the axis yy. Figures 3-9 all depict designs with point symmetry about their x and y axes. Because the polishing pad and substrate rotate during polishing, the x-axis can be parallel to the radius of the polishing pad, perpendicular to the radius of the polishing pad, or any angle between these angles.Typically, however, the x-axis is parallel to and aligned with the radius of the polishing pad. For example, FIGS. 5A and 5B show a circular window 201 having an array of recesses 202 forming circular or cylindrical protrusions 203 in a uniform or symmetrical hexagonal dense pattern. FIG. 5A curves along an axis parallel to its x-axis, an axis parallel to 60 degrees clockwise from its x-axis, and an axis parallel to 120 degrees clockwise from its x-axis. Because the polishing pad and substrate rotate during polishing, the x-axis can be parallel to the radius of the polishing pad, perpendicular to the radius of the polishing pad, or at any angle between these angles. In FIGS. 4A and 4B, recesses 102 form the periphery 104 of window 101 and the lower surface 105 of recess 102 throughout window 101, in that elements 103 do not extend to the edge 104. In Figures 5A and 5B, the recess 202 extends to the periphery 204 and forms the upper surface of the periphery in some areas, but the element 202 may also form the upper surface of the window 201 in other areas of the periphery 204.

[0023] The pattern can be symmetrical in the x-plane through the center point of the window, the y-plane through the center point of the window, or both. The pattern can have point symmetry with respect to a vertical axis through the center point of the window. A uniform window, particularly a symmetric window, provides uniform stiffness reduction and uniform stress relaxation, which facilitates avoiding undesirable asymmetric deflection of the window, while allowing the material used in the window to have a different elastic modulus than the material used in the polishing section. While a symmetric pattern is effective, a slight offset from symmetry can also be effective in providing substantially uniform stiffness reduction. In a rectangular-shaped window, the recesses can be oriented in both the x- and y-coordinate directions. In a circular, elliptical, or polygonal window, at least some of the recesses can be oriented in multiple radial directions to facilitate bending through the center point and parallel directions uniformly spaced from the center point.

[0024] While Figures 4B and 5B show elements 103, 203 separated by recesses 102, 202 at the same size and spacing, respectively, throughout the window, elements of two different sizes or shapes, or recesses of varying widths and depths, could alternatively be used, provided they are uniformly spaced throughout the window. For example, smaller and larger sized shapes could be used in alternate patterns, and small, large, small, large, small across the window in the x and y directions for constant recess dimensions or constant element shapes and sizes could be separated by varying recess widths or depths, provided the variation is uniform in the x and y coordinates throughout the window. As another example, elements of a first size could be placed near the center of the window and elements of a second size could be uniformly spaced around the outside of the window, as shown in the example of Figure 9. 6 and 7, an element 303 or 403 of a first shape can be provided in the center of the window, and elements 303' or 403' of a second shape and size can be uniformly spaced at or near the periphery of the window around the first element 303 or 403. Element 303 or 403 can be a single element, or element 303 or 403 can be a uniform array of elements separated by recesses.

[0025] FIG. 6 shows a circular window 301 having a first recess 302 that is concentric with the window's periphery, defines a central circular protrusion (element) 303, and interconnects additional recesses 302'. Recess 302, together with recess 302', defines the additional protrusions (elements 303') shown having a cut-out pie shape. The additional recesses are radially spaced, preferably at regular or uniform intervals from one another. In particular, recess 302 has a closed, curved shape that connects the recesses 302' that extend toward the periphery 304 of the transparent window 301. While one concentric recess surrounding the circular protrusion element 303 is shown, two, three, or more concentric recesses surrounding a center 307 can also be used. This design allows the entire central protrusion element to be pressed into the cavity below the window during polishing, thereby reducing the window contact pressure against the substrate, such as a semiconductor wafer, being polished.

[0026] FIG. 7 shows an oval window 401 having an oval recess 402 that defines a central ellipse (protruding element) 403 and interconnects with a recess 402' that protrudes outward toward the periphery of the window 401. The recesses 402 and 402' define additional truncated pie-shaped protrusions (protruding elements) 403'. In particular, the recess 402 has a closed, curved shape that connects the recesses 402' that extend toward the periphery 404 of the transparent window 401. Again, a second, third, or more oval recesses 402 may be provided. The central protrusion (protruding element) 303 or 403 can beneficially provide a larger area for the optical element while still providing reduced stiffness and efficient fluid transport. While one concentric recess surrounding the oval-shaped protruding element 403 is shown, two, three, or more concentric recesses surrounding a center 407 may also be used. In particular, this design allows the entire oval-shaped protruding element to be pressed into the cavity below the window during polishing, thereby reducing the window contact pressure against the substrate, such as a semiconductor wafer, being polished. Recesses 302' and 402' can extend to and form part of peripheral edge 304 or 404, respectively, and elements 303' and 403' can also form part of peripheral edge 304 or 404. The recesses may be misaligned with the polishing pad grooves, may be offset from the polishing pad grooves, or may be partially aligned with the polishing pad grooves.

[0027] FIG. 8 shows a window 801 having both concentric circular recesses 802 and grid recesses 804. These recesses combine to define elements 803 with various shapes, including squares, rectangles, and triangles, which may be modified with curved inner or outer edges. The recesses include one or more recessed rings 802 concentric with the periphery of the circular window 801 and linear recesses 804 extending in a uniform pattern throughout the window 801. The circular recesses 802 allow the internal protruding elements to recess inward into the recess cavities (not shown). An advantage of the concentric rings is that the force required to depress the window gradually decreases as the center of the recess 807 is reached. In addition to reducing the deflection force on the protruding elements 803 within the concentric region, the grid recesses 804 allow bending along the recess 804 parallel to the x and y directions. This window exhibits point symmetry or substantial point symmetry (if the pattern is slightly offset from the center). The recess 804 may extend to a peripheral edge 805 of the window 801. The upper surface of the peripheral edge 805 may be formed by the recess 804 and the element 803 located at such peripheral edge 805.

[0028] FIG. 9 shows a window 901 having an inner portion with small elements 903 and recesses 902, with larger elements 905 and larger recesses 904 around the periphery of the window. The pattern includes a first set of elements 903 separated by a first set of recesses 902, which are surrounded by a second set of elements 905 and a second set of recesses 904, with the second set of elements 905 being larger than the first set of elements 903 and the second set of recesses 904 being larger than the recesses 902 in the first set 902. The window exhibits point symmetry, or if slightly offset from the center, would be substantially point symmetric. The recesses 904 can form the periphery of the window 901. The recesses 904 allow the internal protruding elements 903 to flex inward into recess cavities (not shown). In addition to reducing the bending force on the central protruding element 903, the grid recesses 902 allow bending parallel to the x and y directions. Recesses 902 and 904 combine to reduce the bending force to a minimum at the center 907.

[0029] The size of the polishing pad can be at least 10 centimeters (cm), at least 20 cm, at least 30 cm, at least 40 cm, or at least 50 cm, up to 100 cm, up to 90 cm, or up to 80 cm. The pad can be provided in any shape, but may conveniently have a circular or disc shape with a diameter in the ranges mentioned above. The window can have a length and width (or diameter, in the case of a circular window) dimension of at least 0.5 cm, or at least 1 cm, up to 3 cm, or up to 2.5 cm, up to 2 cm, or up to 1 cm.

[0030] The polishing pad can have a total thickness of at least 1 mm and up to 4 mm or up to 3 mm. The window thickness can be less than the total thickness of the pad. If the pad includes an upper polishing portion on a subpad, the window thickness can be greater than the thickness of the upper polishing portion (but not greater than the total thickness of the pad (e.g., upper pad thickness + subpad thickness)). The polishing portion thickness can be at least 1 mm, or at least 1.1 mm and up to 3 mm, or up to 2.5 mm. The window thickness can be at least 0.5 mm, at least 0.75 mm, or at least 1 mm and up to 3 mm, up to 2.9 mm, or up to 2.5 mm. The recess depth can be at least 10% and up to 60% or up to 50% of the window thickness. The recess depth can be at least 0.2 mm or at least 0.3 mm and up to 2 mm or up to 1.5 mm. The recess width can be at least 0.3 mm, at least 0.5 mm, or at least 0. The recesses can be 8 mm up to 10 mm, up to 5 mm, up to 3 mm, up to 2 mm, or up to 1.5 mm. The recesses can be up to 30%, up to 20%, or up to 10% of the largest dimension of the window. The elements separated by the recesses can have dimensions (e.g., length, width, radius) of at least 0.3 mm, or at least 0.5 mm, or at least 0.8 mm up to 10 mm, up to 8 mm, up to 6 mm, up to 5 mm, up to 4 mm, up to 3 mm, or up to 2 mm. There can be at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, or at least 10 elements, up to 200, up to 150, up to 100, up to 50, up to 40, or up to 30 elements separated by recesses in the window.

[0031] As shown in Figures 3A and 3B, the polishing portion 15 can have grooves 12. While concentric grooves are shown, other groove patterns, such as radial grooves or crosshatch grooves, can also be used. Alternatively, the polishing portion of the pad can have other textures. The polishing portion of the pad can be porous, formed from a lattice of material, or have other patterns thereon. The recesses of the window can be aligned with the grooves of the polishing portion. Alternatively, the recesses of the window can be positioned so that they are not aligned or are partially misaligned with the grooves of the polishing portion. Typically, the majority of the recesses are not aligned with the grooves of the polishing layer.

[0032] The window can comprise a variety of flexible materials, provided they transmit the signals used in endpoint detection. For example, the window can comprise thermoplastic and thermosetting polymers. Examples of such thermoplastic polymers include polyurethane, polyolefin, polystyrene, polysulfone, polyacrylate, polycarbonate, fluorinated polymer, and polyacetal. Examples of such thermosetting polymers include polyurethane, phenolic, polyester, epoxy, and silicone. The selection of a particular window polymer depends on achieving an appropriate match between the conditioning wear rate for the upper pad layer and the level of light transmission that can be achieved in the final pad for the functional requirements of the particular optical endpoint detection device being used (i.e., suitability for optical measurements). It should be appreciated that the window design of the present invention offers greater flexibility compared to prior art designs. The window can be transparent to electromagnetic radiation with wavelengths of at least 190 nm, at least 200 nm, or at least 22 nm up to 1200 nm, up to 850 nm, or up to 650 nm. The window material may have a Young's modulus according to ASTM D 412-16 of at least 4 MPa, at least 10 MPa, or at least 100 MPa, or at least 0.2 Gpa, at least 0.3 Gpa, at least 0.4 Gpa, at least 0.5 Gpa, at least 0.7 Gpa, or at least 1 Gpa up to a maximum of 10 Gpa, or up to a maximum of 5 Gpa, or up to a maximum of 2 Gpa.

[0033] The windows disclosed herein can be manufactured using a wide variety of materials and techniques. Some exemplary techniques include machining the top surface of the window to form the desired pattern of interconnected recesses. Alternatively, the window may be cast into a mold containing the inverse pattern of the desired recess arrangement to produce the final net-shape window. In the case of thermoplastic polymers, net-shape windows can also be fabricated by hot pressing, injection molding, etc. Windows can be made by additive manufacturing.

[0034] The polishing portion can include any composition commonly used in polishing pads. The polishing portion can include a thermoplastic polymer or a thermosetting polymer. The polishing portion can be a composite material, such as a composite material including a polymer filled with carbon or inorganic fillers and a fibrous mat, such as glass or carbon fibers, impregnated with the polymer. The polishing portion can have voids. Examples of polymers that can be used in the base pad or polishing portion include polycarbonate, polysulfone, nylon, epoxy resin, polyether, polyester, polystyrene, acrylic polymer, polymethyl methacrylate, polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, polybutadiene, polyethyleneimine, polyurethane, polyethersulfone, polyamide, polyetherimide, polyketone, epoxy, silicone, copolymers thereof (e.g., polyether-polyester copolymers), and combinations or blends thereof. The polymer can be polyurethane.

[0035] The abrasive portion may have a Young's modulus according to ASTM D 412-16 of at least 2 MPa, at least 2.5 MPa, at least 5 MPa, at least 10 MPa, or at least 50 MPa up to 900 MPa, up to 700 MPa, up to 600 MPa, up to 500 MPa, up to 400 MPa, up to 300 MPa, or up to 200 MPa. The abrasive portion may be opaque to signals used for endpoint detection.

[0036] A base pad (also called an underlayer or base layer) can be used under the polishing portion. The base pad can be a single layer or can include two or more layers. The use of a base pad provides a cavity to allow bending of the window by removing the base pad or subpad under the window. The top surface of the base pad can define a plane in an x-y Cartesian coordinate system. For example, the polishing portion can be attached to the subpad via mechanical fasteners or by adhesive. The base layer can have a thickness of at least 0.5 mm or at least 1 mm. The base layer can have a thickness of 5 mm or less, 3 mm or less, or 2 mm or less.

[0037] The base pad or base layer can be made of any material known for use as a base layer for a polishing pad. For example, it can include polymers, composites of polymer materials with other materials, ceramics, glass, metals, stone, or wood. Due to their compatibility with materials that can form the polishing portion, polymers and polymer composites can be used as the base pad, especially for the top layer when there are two or more layers. Examples of such composites include polymers filled with carbon or inorganic fillers, and fibrous mats, such as glass or carbon fibers, impregnated with polymers. The base of the pad can be made of a material having one or more of the following properties: a Young's modulus, as determined, for example, by ASTM D412-16, in the range of at least 2 MPa, at least 2.5 MPa, at least 5 MPa, at least 10 MPa, or at least 50 MPa up to 900 MPa, up to 700 MPa, up to 600 MPa, up to 500 MPa, up to 400 MPa, up to 300 MPa, or up to 200 MPa; a Poisson's ratio, as determined, for example, by ASTM E 132015, of at least 0.05, at least 0.08, or at least 0.1 up to 0.6, or up to 0.5; a viscosity of at least 0.4 grams per cubic centimeter (g / cm 3 ), or at least 0.5 g / cm 3 up to 1.7g / cm3 up to 1.5g / cm 3 up to 1.3g / cm 3 Density up to.

[0038] Examples of such polymeric materials that can be used in the base pad or polishing portion include polycarbonate, polysulfone, nylon, epoxy resin, polyether, polyester, polystyrene, acrylic polymer, polymethyl methacrylate, polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, polybutadiene, polyethyleneimine, polyurethane, polyethersulfone, polyamide, polyetherimide, polyketone, epoxy, silicone, copolymers thereof (e.g., polyether-polyester copolymers), and combinations or blends thereof.

[0039] The polymer may be a polyurethane, which may be used alone or in a matrix of carbon or inorganic fillers and a fibrous mat of, for example, glass or carbon fibers.

[0040] For purposes of this specification, "polyurethane" refers to a product derived from a difunctional or polyfunctional isocyanate, such as polyetherurea, polyisocyanurate, polyurethane, polyurea, polyurethaneurea, copolymers thereof, and mixtures thereof. A corresponding CMP polishing pad can be made by a method including: providing an isocyanate-terminated urethane prepolymer; separately providing a curing agent component; and combining the isocyanate-terminated urethane prepolymer with the curing agent component to form a combination, and reacting the combination to form a product. A base pad or base layer can be formed by skiving a cast polyurethane cake to a desired thickness. Optionally, preheating the cake mold with infrared radiation, induction, or direct current can reduce product variability when casting a porous polyurethane matrix. Optionally, either a thermoplastic polymer or a thermosetting polymer can be used. The polymer can be a crosslinked thermosetting polymer.

[0041] When polyurethane is used in the base pad or polishing layer, the polyurethane may be a reaction product of a polyfunctional isocyanate and a polyol. For example, a polyisocyante-terminated urethane prepolymer may be used. The polyfunctional isocyanate used in forming the polishing layer of the chemical mechanical polishing pad of the present invention may be selected from the group consisting of aliphatic polyfunctional isocyanates, aromatic polyfunctional isocyanates, and mixtures thereof. For example, the polyfunctional isocyanate used in forming the polishing layer of the chemical mechanical polishing pad of the present invention can be a diisocyanate selected from the group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, tolidine diisocyanate, paraphenylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, and mixtures thereof. The polyfunctional isocyanate can be an isocyanate-terminated urethane prepolymer formed by the reaction of a diisocyanate with a prepolymer polyol. The isocyanate-terminated urethane prepolymer may have 2 to 12 weight percent, 2 to 10 weight percent, 4 to 8 weight percent, or 5 to 7 weight percent unreacted isocyanate (NCO) groups. The prepolymer polyol used to form the polyfunctional isocyanate-terminated urethane prepolymer may be selected from the group consisting of diols, polyols, polyol diols, copolymers thereof, and mixtures thereof.For example, the prepolymer polyol may be selected from the group consisting of polyether polyols (e.g., poly(oxytetramethylene) glycol, poly(oxypropylene) glycol, and mixtures thereof); polycarbonate polyols; polyester polyols; polycaprolactone polyols; mixtures thereof; and mixtures thereof with one or more low molecular weight polyols selected from the group consisting of ethylene glycol; 1,2-propylene glycol; 1,3-propylene glycol; 1,2-butanediol; 1,3-butanediol; 2-methyl-1,3-propanediol; 1,4-butanediol; neopentyl glycol; 1,5-pentanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; and tripropylene glycol. For example, the prepolymer polyol may be selected from the group consisting of polytetramethylene ether glycol (PTMEG); ester-based polyols (ethylene adipate, butylene adipate, etc.); polypropylene ether glycol (PPG); polycaprolactone polyols; copolymers thereof; and mixtures thereof. For example, the prepolymer polyol may be selected from the group consisting of PTMEG and PPG. When the prepolymer polyol is PTMEG, the isocyanate-terminated urethane prepolymer may have an unreacted isocyanate (NCO) concentration of 2 to 10 wt % (more preferably 4 to 8 wt %; most preferably 6 to 7 wt %).Examples of commercially available PTMEG-based isocyanate-terminated urethane prepolymers include Imuthane® prepolymers (available from COIM USA, Inc., such as PET-80A, PET-85A, PET-90A, PET-93A, PET-95A, PET-60D, PET-70D, and PET-75D); Adiprene® prepolymers (available from Chemtura, such as LF 800A, LF 900A, LF 910A, LF 930A, LF 931A, LF 939A, LF 950A, LF 952A, LF 600D, LF 601D, LF 650D, LF 667, LF 700D, LF 750D, LF 751D, LF 752D, LF 753D, and L 325); and Andur® prepolymers (available from Anderson Development Available from Polypropylene Co., Inc. include 70APLF, 80APLF, 85APLF, 90APLF, 95APLF, 60DPLF, 70APLF, 75APLF, etc. When the prepolymer polyol is PPG, the isocyanate-terminated urethane prepolymer may have an unreacted isocyanate (NCO) concentration of 3 to 9 wt % (more preferably 4 to 8 wt %, most preferably 5 to 6 wt %). Examples of commercially available PPG-based isocyanate-terminated urethane prepolymers include Imuthane® prepolymers (available from COIM USA, Inc., such as PPT-80A, PPT-90A, PPT-95A, PPT-65D, and PPT-75D); Adiprene® prepolymers (available from Chemtura, such as LFG 963A, LFG 964A, and LFG 740D); and Andur® prepolymers (available from Anderson Development Company, such as 8000APLF, 9500APLF, 6500DPLF, and 7501DPLF). The isocyanate-terminated urethane prepolymer may be a low-free isocyanate-terminated urethane prepolymer having a free toluene diisocyanate (TDI) monomer content of less than 0.1% by weight. Non-TDI-based isocyanate-terminated urethane prepolymers can also be used.For example, isocyanate-terminated urethane prepolymers are acceptable, including those formed by reacting a polyol such as 4,4'-diphenylmethane diisocyanate (MDI) and polytetramethylene glycol (PTMEG) with an optional diol such as 1,4-butanediol (BDO). When such isocyanate-terminated urethane prepolymers are used, the unreacted isocyanate (NCO) concentration is preferably 4 to 10 wt % (more preferably 4 to 10 wt %, most preferably 5 to 10 wt %). Examples of commercially available isocyanate-terminated urethane prepolymers in this category include Imuthane® prepolymers (available from COIM USA, Inc., such as 27-85A, 27-90A, and 27-95A), Andur® prepolymers (available from Anderson Development Company, such as IE75AP, IE80AP, IE85AP, IE90AP, IE95AP, and IE98AP); and Vibrathane® prepolymers (available from Chemtura, such as B625, B635, and B821).

[0042] The final pad containing a window as disclosed herein can be manufactured by several techniques, including, but not limited to, fabricating a separate window with a desired pattern of recesses on the upper surface of the window, followed by inserting it into an opening in the upper pad layer aligned with the opening in the subpad layer (a so-called insert window). A sealant or adhesive can be used to secure the window within the polishing pad. Examples of such materials include pressure-sensitive adhesives, acrylics, polyurethanes, and cyanoacrylates. Alternatively, a block of window material can be machined to the cross-sectional dimensions of the final window. This block is placed in a mold, around which the upper pad layer material is cast. The resulting composite cylinder can then be sliced ​​into sheets of the desired thickness, after which the texture on the upper surface of the window is manufactured. Alternatively, the windowed pad can be formed by casting the polishing section around the completed window via techniques such as injection molding or compression molding, producing a single net-shape upper pad layer with the composite window cast in place.

[0043] method The polishing pads disclosed herein can be used to polish substrates. For example, a polishing method can include providing a substrate to be polished and then using a pad disclosed herein to polish the substrate by contacting the protrusions with the substrate. The substrate can be any substrate for which polishing and / or planarization is desired. Examples of such substrates include magnetic substrates, optical substrates, and semiconductor substrates. The method can be used for component substrate processing or wiring processing for integrated circuits. For example, this process can be used to remove undesirable surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials. Furthermore, in damascene processes, material is deposited to fill recessed areas formed by one or more steps of photolithography, patterned etching, and metallization. Certain steps can be imprecise, for example, resulting in overfill of the recess. The method disclosed herein can also be used to remove material outside the recess. This process can be chemical mechanical planarization or chemical mechanical polishing, both of which can be referred to as CMP. The carrier can hold the substrate to be polished, for example, a semiconductor wafer (with or without layers formed by lithography and metallization), in contact with the polishing elements of the polishing pad. Slurry or other abrasives can be dispensed into the gap between the substrate and the polishing pad. The polishing pad and the substrate are moved relative to each other, for example, rotated. The polishing pad is typically positioned below the substrate to be polished. The polishing pad can rotate. The substrate to be polished can also move on a polishing track, for example, an annular shape. The relative movement brings the polishing pad into close contact with the surface of the substrate.

[0044] For example, this method can include providing a chemical mechanical polishing apparatus having a platen or carrier assembly, providing at least one substrate to be polished, providing a chemical mechanical polishing pad as disclosed herein, placing the chemical mechanical polishing pad on the platen, optionally providing an abrasive (e.g., a slurry and / or a non-abrasive-containing reactive liquid composition) at the interface between the polishing portion of the chemical mechanical polishing pad and the substrate, and creating dynamic contact between the polishing portion of the polishing pad and the substrate, whereby at least some material is removed from the substrate. The carrier assembly can provide a controllable pressure between the substrate (e.g., a wafer) being polished and the polishing pad. The abrasive can be dispensed onto the polishing pad and drawn into the gap between the wafer and the polishing layer. The abrasive can include water, a pH adjuster, and optionally one or more of, but not limited to, abrasive grains, oxidizers, inhibitors, biocides, soluble polymers, and salts. The abrasive particles can be oxide, metal, ceramic, or other suitable hardness materials. Typical abrasive particles are colloidal silica, fumed silica, ceria, and alumina. The polishing pad and substrate can rotate relative to each other. As the polishing pad rotates under the substrate, the substrate typically sweeps out a circular polishing track, or polishing area, with the wafer surface directly facing the polishing portion of the polishing pad. The wafer surface is polished and made flat by the chemical-mechanical action of the polishing layer and the abrasive on the surface. Optionally, the polishing surface of the polishing pad can be conditioned with an abrasive conditioner before polishing begins. In the method of the present invention, the chemical mechanical polishing apparatus provided further includes a signal source (e.g., a light source) and a signal detector (e.g., a light sensor (preferably a multi-sensor spectrometer). The method can therefore include determining a polishing endpoint by transmitting a signal (e.g., light from the light source) through a window and analyzing the signal (e.g., light) reflected from the surface of the substrate through the endpoint detection window and incident on a sensor (e.g., a light sensor).The substrate may have a metal or metallized surface, such as one containing copper or tungsten. The substrate may be a magnetic substrate, an optical substrate, or a semiconductor substrate.

[0045] Example 1 Polishing pads were fabricated incorporating a window design as shown in Figure 5. The window (301) was circular, 18 mm in diameter, and 2.032 mm thick. These dimensions are comparable to those found in prior art window pads. Samples were fabricated from several materials capable of transmitting UV / visible light in the wavelength range of 250-800 nm.

[0046] The recess design consists of a central convex region or element (303) with a diameter of 6 mm and no recesses, and an outer region of eight polygonal convex regions or elements (303'). The surfaces of all convex elements are flush with the polishing pad top surface, and the bottom of the window (301) is flush with the interface between the polishing portion (i.e., the polishing layer) and the lower layer (i.e., the sublayer or base layer) of the polishing pad. Between the central region and the polygonal region is a circular concave region (302) with a width of 1.524 mm and a depth of 0.762 mm. Each polygonal convex region (303') is separated by eight concave regions (302') with the same width and depth as the circular concave region (302) that intersects it, providing a continuous recess pattern that can aid in slurry transport.

[0047] The complete sample was tested on an Applied Materials Reflexion™ LK CMP tool incorporating a proprietary optical endpoint detector. The optical signal strength of the exemplary pad was found to be within the normal range for commercial use. This example refutes the expectation that multiple depressions in the window would cause the optical signal to be weak, irregular, and unacceptable for wafer endpoint detection.

[0048] Comparative Example A pad containing a circular window, as shown in FIGS. 10A and 10B, was fabricated. The window 110 had concentric grooves 111 and features 112 of varying heights separated by grooves 113 in a V-shape. The pad was not uniform in that the pattern was inconsistent in the x and y directions and lacked point symmetry or substantial point symmetry about the center 117. Furthermore, the central protruding element had a width greater than half the width or diameter of the window 110. This caused the flow of slurry around the feature 112 to become serpentine, with a terminal end collecting the slurry. Both the serpentine flow and the collection of slurry resulted in undesirable polishing defects. Attempts to polish using a sensor for detection through the window exhibited an unacceptably high signal-to-noise ratio, making the sensor ineffective. Additionally, the compliance of the window was not uniform in the x and y directions, such that the window could deflect more in one direction than the other.

[0049] The present disclosure further encompasses the following aspects.

[0050] Aspect 1: A polishing pad having an upper polishing surface, a bottom layer for attachment to a platen, and a polishing material, the upper polishing surface including a groove; an opening through the polishing pad; and a transparent window within the opening of the polishing pad, the transparent window being flexible and having a thickness measured from the bottom of the transparent window to the upper polishing surface of the transparent window, the transparent window being fixed to the polishing pad in a state spaced apart from the platen to form a cavity, the transparent window transmitting at least one of a magnetic signal and an optical signal; the transparent window having a plurality of protruding elements filling a periphery and a center of the transparent window, the tops of the plurality of protruding elements representing the upper polishing surface of the transparent window, the protruding elements having an initial height of at least 30 percent of the thickness of the transparent window; and the protruding elements having a protruding element pattern on an upper surface. 1. A polishing pad useful in chemical mechanical polishing of semiconductor substrates, optical substrates, or magnetic substrates, comprising: a transparent window flush with an upper polishing surface separated by interconnected recesses extending to the periphery of the transparent window to form turns, most of the recesses being partially or completely misaligned with the grooves in the upper polishing surface; a protruding element pattern that allows the transparent window to bend into the cavity about multiple axes, at least two of which are non-parallel to or with the central protruding element; and a central protruding element surrounded by one or more recesses that bend downward into the cavity with the central protruding element, the central protruding element having a width less than half the longest dimension of the transparent window to reduce contact pressure with the substrate during polishing.

[0051] Aspect 2: A polishing pad according to aspect 1, wherein the transparent window has a center and the protruding elements and recesses have point symmetry with respect to the center.

[0052] Embodiment 3: The polishing pad of embodiment 1 or 2, wherein the recesses form a cross-hatch pattern.

[0053] Embodiment 4: The polishing pad of any one of the previous embodiments, wherein the protruding elements have a cylindrical shape.

[0054] Embodiment 5: The polishing pad of any one of the preceding embodiments, wherein the recesses comprise closed, curved shapes connecting the recesses that extend toward the periphery of the transparent window.

[0055] Embodiment 6: The polishing pad of any one of the preceding embodiments, wherein the pattern comprises closely spaced hexagonal protruding elements.

[0056] Aspect 7: A polishing pad described in any one of the preceding aspects, wherein the pattern includes a first group of elements separated by a first group of recesses, the first group of elements and the first set of recesses being surrounded by a second group of elements and a second set of recesses, the elements of the second group being larger than the elements of the first group, and the recesses of the second set being larger than the recesses of the first set.

[0057] Embodiment 8: The polishing pad of any one of the preceding embodiments, wherein the recesses include one or more recessed rings concentric with the periphery of the circular window and linearly extending recesses in a uniform pattern across the window.

[0058] Embodiment 9: The polishing pad of any one of the preceding embodiments, wherein the pattern has point symmetry with respect to its x-axis and y-axis.

[0059] Embodiment 10: The polishing pad of any one of the previous embodiments, wherein the depth of the recess is 30 to 60 percent, preferably 35 to 55 percent, of the thickness of the window.

[0060] Embodiment 11: The polishing pad of any one of the previous embodiments, wherein there are 4 to 200 elements, preferably 10 to 100 elements.

[0061] Embodiment 12: The polishing pad of any one of the previous embodiments, having at least 4 to 100 recesses, preferably 10 to 50 recesses.

[0062] Embodiment 13: The polishing pad of any one of the preceding embodiments, wherein the recesses are in the form of grooves.

[0063] Embodiment 14: The polishing pad of any one of the preceding embodiments, wherein the polishing portion comprises a series of cylinders.

[0064] Embodiment 15: The polishing pad of embodiment 14, wherein the grooves of the polishing pad are aligned with the recesses.

[0065] Embodiment 16: The polishing pad of embodiment 14, wherein the grooves are not aligned with the recesses.

[0066] Embodiment 17: The polishing pad of any one of the preceding embodiments, wherein the compliance of the window to stress is consistent along the parallel axes of the x and y directions.

[0067] Embodiment 19: The polishing pad of any one of the previous embodiments, wherein the recesses have a width of 0.3 to 10 mm, preferably 0.5 to 3 mm.

[0068] Embodiment 20: The polishing pad of any one of the previous embodiments, wherein the elements have dimensions of 0.3 to 10 mm, preferably 0.5 to 5 mm, and more preferably 0.8 to 3 mm.

[0069] Aspect 21: A polishing method comprising: providing a substrate; polishing the substrate using a polishing pad described in any one of the preceding aspects; providing an optical or magnetic signal, preferably an optical signal, through a transparent window; detecting a response to the signal; and monitoring the response to determine that polishing is complete.

[0070] Aspect 22: The method of aspect 21, wherein the abrasive, preferably a slurry, and material removed during polishing are transferred from the substrate through the recesses.

[0071] The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of any suitable material, step, or component disclosed herein. The compositions, methods, and articles can additionally or alternatively be constructed to be devoid of, or substantially free of, any material (or species), step, or component that is not necessary to achieve the function or purpose of the compositions, methods, and articles.

[0072] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., the range "up to 25 wt.%, or more specifically, 5 wt.% to 20 wt.%" includes the endpoints of the range "5 wt.% to 25 wt.%, and all intermediate values). Additionally, recited upper and lower limits may be combined to form ranges (e.g., "at least 1 or at least 2 wt.%" and "up to 10 or 5 wt.%" can be combined to form the range "1 to 10 wt.%" or the range "1 to 5 wt.%" or the range "2 to 10 wt.%" or the range "2 to 5 wt.%). "Combination" includes blends, mixtures, alloys, reaction products, and the like. Terms such as "first," "second," and the like do not denote order, quantity, or importance, but rather are used to distinguish one element from another. The terms "a," "an," and "the" do not denote a limitation of quantity and should be construed to encompass both the singular and the plural unless otherwise indicated herein or clearly contradicted by context. "Or" means "and / or" unless otherwise stated. Throughout this specification, references to "some embodiments," "one embodiment," etc., mean that the elements described in connection with that embodiment are included in at least one embodiment described herein and may or may not be present in other embodiments. Additionally, it should be understood that the described elements may be combined in any suitable manner in various embodiments. "Combinations thereof" are open-ended and include any combination that includes at least one of the described components or features, optionally together with similar or equivalent components or features that are not described.

[0073] Unless specified to the contrary herein, all test standards are the latest standards in effect as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the test standards are listed.

Claims

1. 1. A polishing pad useful in chemical mechanical polishing of semiconductor, optical or magnetic substrates, comprising: a polishing section having an upper polishing surface, a bottom layer for attachment to a platen, and a polishing material, the upper polishing surface including grooves; an opening through the polishing pad; a transparent window in the opening of the polishing pad, the transparent window being flexible and having a thickness measured from a bottom of the transparent window to the upper polishing surface of the transparent window, the transparent window being fixed to the polishing pad in a spaced relationship from the platen to form a cavity below the bottom of the transparent window, and the transparent window transmitting at least one of magnetic and optical signals; the transparent window has a plurality of protruding elements on an upper surface of the transparent window; the tops of the plurality of protruding elements represent the upper polishing surface of the transparent window, the protruding elements have an initial height of at least 30 percent of the thickness of the transparent window, the protruding elements are flush with the upper polishing surface separated by interconnected recesses that extend to a periphery of the transparent window to provide a protruding element pattern on the upper surface, the recesses being partially or completely misaligned with the grooves in the upper polishing surface; the protruding element pattern allows bending about multiple axes by i) bending the transparent window into the cavity and at least two of the axes about which bending is carried out are non-parallel; or the protruding element pattern allows bending about multiple axes by ii) bending at recesses to form a central protruding element, the central protruding element surrounded by one or more recesses that bend downward into the cavity, the central protruding element having a width less than half the longest dimension of the transparent window, the longest dimension of the transparent window being in a direction parallel to the upper polished surface; a transparent window, wherein the bending of the transparent window according to i) and ii) is for reducing contact pressure with the substrate during polishing; 1. A polishing pad comprising:

2. 2. The polishing pad of claim 1, wherein the transparent window has a center, and the protruding elements and the interconnected recesses have point symmetry about the center.

3. The polishing pad of claim 1 , wherein the protruding element pattern has axisymmetrical relation with respect to the x-axis and the y-axis.

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