CN118418036A

CN118418036A - Polishing pad with endpoint window

Info

Publication number: CN118418036A
Application number: CN202410137260.7A
Authority: CN
Inventors: 苏于中
Original assignee: Rohm and Haas Electronic Materials CMP Holdings Inc
Current assignee: Rohm and Haas Electronic Materials CMP Holdings Inc
Priority date: 2023-01-31
Filing date: 2024-01-31
Publication date: 2024-08-02

Abstract

A polishing pad for chemical mechanical polishing includes a polishing layer having a top polishing surface, a bottom surface, and a thickness. The polishing layer includes a porous polishing material and a window region. The exposed top surface of the transparent window is recessed from the top polished surface. A transparent window extends from the recessed region to the bottom surface of the polishing pad. The transparent window is imperforate and a portion of the top surface adjacent the peripheral portion of the transparent window is coplanar with the top surface of the transparent window and the exposed bottom surface of the transparent window is coplanar with the bottom surface of the polishing layer.

Description

Polishing pad with endpoint window

Technical Field

The field of the invention is polishing pads for chemical mechanical polishing.

Background

Chemical Mechanical Planarization (CMP) is a variation of the polishing process that is widely used to planarize or planarize build-up layers of integrated circuits, or similar structures. In particular, CMP is often used to produce a planar uniform layer of defined thickness in the fabrication of three-dimensional circuit structures built by an additive stacking and planarization process. The CMP process removes excess deposited material on the surface of the substrate (e.g., wafer) to produce an extremely flat layer of uniform thickness, wherein the uniformity extends throughout the entire substrate (e.g., wafer) area. When a uniform thickness is across the entire wafer, it is referred to as overall uniformity.

CMP uses a liquid (commonly referred to as a slurry) that may contain nano-sized particles. The slurry is fed onto the surface of a rotating multi-layer polymeric mat (sometimes referred to as a polishing sheet) that is mounted on a rotating platen. The polishing pad includes a polishing layer and may include a subpad. The substrate (e.g., wafer) is mounted into a separate fixture or carrier having a separate rotating device and pressed against the surface of the pad under a controlled load. This can result in a high rate of relative movement between the substrate (e.g., wafer) and the polishing pad, and in a resulting high shear rate or wear at the substrate and pad surfaces. The shear and the slurry particles trapped at the pad/substrate interface abrade the substrate (e.g., wafer) surface, causing material to be removed from the substrate surface. Controlling the removal rate and uniformity of removal is important to achieving overall uniformity.

Various types of film thickness metrology and real-time control software can be used to achieve device design goals. One approach to endpoint detection is to use light of a desired wavelength to transmit through the polishing pad, reflect light from the substrate being polished, and then return the reflected light signal to an interferometer, which processes the reflected signal to determine whether the polishing has reached its desired target (e.g., film thickness, expected exposure of underlying structures). The metrology equipment may be located within the body of the platen of the holding pad. This requires that at least a portion of the polishing pad be sufficiently transparent to the light source used to produce an acceptable signal-to-noise ratio.

For some pad structures, the pad material itself may be transparent to the desired wavelength of light. Alternatively, a plug of transparent polymer and an opaque material molded around it may be provided to create a transparent window. See, for example, U.S.5,605,760. A third method is to form a pad with holes into which a transparent window material is inserted and secured in place with an adhesive. See, for example, U.S.5,893,796. Various versions of these pads with windows have been proposed. See, for example, U.S.7,621,798, U.S.8,475,228, U.S.10,569,383, U.S.2021/0402556, U.S.9,475,168.

The use of two different materials in the pad may lead to problems in use, including one or more of the following: scratches or defects of the substrate being polished, limited usable life of the pad due to differences in wear rates of the window compared to the polishing layer, or sticking problems between the transparent window material and the polishing pad material. Thus, there remains a need for an improved polishing pad having a transparent window.

Disclosure of Invention

Disclosed herein is a polishing pad for chemical mechanical polishing comprising a polishing layer having a top polishing surface, a bottom surface, and a thickness, the polishing layer comprising a porous polishing material and a window region, wherein the window region comprises a transparent window having an exposed top surface and an exposed bottom surface to enable transmission of light through the polishing pad in the window region, the exposed top surface of the transparent window being recessed from the top polishing surface, the transparent window extending from the recessed region to the bottom surface of the polishing pad, the window region further comprising a peripheral portion of the polishing material in contact with a side edge of the transparent window, the peripheral portion of the polishing material having a top surface recessed from the top surface of the top polishing surface, and wherein the transparent window is non-porous, and wherein a portion of the top surface adjacent to the peripheral portion of the transparent window is coplanar with the top surface of the transparent window, and wherein the exposed bottom surface of the transparent window is coplanar with the bottom surface of the polishing layer.

Drawings

Reference is now made to the drawings, which are exemplary embodiments, and wherein like elements are numbered alike.

Fig. 1 is a cross-sectional view of one example of a polishing pad as disclosed herein.

Fig. 2 is a cross-sectional view of one example of a polishing pad as disclosed herein.

Fig. 3 is a cross-sectional view of one example of a polishing pad as disclosed herein.

Fig. 4 is a top view of the upper surface of an example of a pad of the present invention, wherein the optical window shape is rectangular.

Fig. 5 is a top view of the upper surface of an example of a pad of the present invention, wherein the optical window shape is elliptical.

Detailed Description

Disclosed herein is a polishing pad useful for chemical mechanical polishing having a design that minimizes the risk of substrate defects caused by the use of different materials for the polishing material and the transparent window while also minimizing adhesion problems between the transparent window and the polishing material. In particular, the polishing pad comprises a polishing layer and a window region. The polishing layer has a top polishing surface and a thickness. The polishing layer comprises a polishing material. The window region is recessed from the top polishing surface. The window region includes a transparent window having an exposed top surface and an exposed bottom surface to enable light to be transmitted through the polishing pad in the window region. The window region further includes a peripheral portion of polishing material in contact with the side edges of the transparent window, wherein the peripheral portion of polishing material further has a top surface recessed from the top surface of the top polishing surface. The peripheral portion may be a protrusion. By having a window area recessed from the top polishing surface of the pad and including a transparent window and a peripheral portion (or protrusion) of the polishing material, the useful life of the polishing pad can be increased and defects created by the different characteristics of the transparent window material and the polishing material can be reduced.

In particular, many existing polishing pads having transparent windows require at least a portion of the window to be coplanar with the top polishing surface to ensure good transmission of light through the window and to the surface of the substrate being polished. However, since the composition of the window material is different from the polishing material, different mechanical properties during use-localized differences in contact pressure and texture are observed, which can lead to uneven polishing rates and increased wafer scale non-uniformity. Further, since the polishing pad is typically dressed with a bonded diamond abrasive during use to maintain a constant polishing rate, differences in dressing wear rates between the upper pad material and the window during continued use may result in protrusions of the window area. It is generally observed that the development of such protrusions results in a higher level of scratch defects and often results in the pad being replaced, thereby increasing manufacturing costs, resulting in scratches and defects on the substrate being polished. Differential thinning of the window during use may also interfere with the optical signal. The difference in thermal expansion coefficients between the polishing material and the window material may cause additional stress and deformation.

Having such recessed window regions: the recessed window region has a top window surface recessed below the top polishing surface along with a peripheral portion of the polishing material that is also recessed below the top polishing surface, which aids in stress relief in the pad and also avoids the window material protruding above the top polishing surface (which may cause defects or scratches).

Fig. 1, 2 and 3 illustrate cross-sections of three examples of polishing pads 100 as disclosed herein. The polishing pad 100 has a polishing layer 120 with a top polishing surface 110 having a thickness a and a window region 103. Polishing layer 120 is porous and includes porous polishing material 101. Fig. 1, 2 and 3 illustrate an optional macro-texture 102 on the top surface 100 of the polishing layer 120. The macro-texture 102 may be a groove, protrusion, or raised feature to enhance polishing and management of slurry fluids and removal materials. The macro texture may for example be in the form of grooves having a depth b and a width g. The macro texture 102 may be spaced apart from the window region 103. Alternatively, the macro texture may intersect the recessed peripheral portion 105 of the window region 103. Window region 103 includes a transparent window 104 having a top surface 104a and a bottom surface 104 b. The transparent window 104 is non-porous to facilitate transmission of light to optically measure the polishing endpoint. The window region also includes a peripheral portion 105 having a top surface 105 a. The transparent window 104 extends from a top surface 105a of the peripheral portion to a bottom surface 105b of the polishing layer 120. Typically, there is no chemical bond between the transparent window 104 and the polishing layer 120. This lack of chemical bonding between the materials makes it critical that the transparent window extend the entire length from the top surface 105a to the bottom surface 105b. This extension from top surface 105a to bottom surface 105b results in increased contact, which increases the friction holding the window in place during polishing.

The transparent window 104 preferably has the same thickness as the thickness from the top surface 104a to the bottom surface 104b as measured across the transparent window 104. This reduces light distortion and makes the top surface 104a of the transparent window 104 coplanar with the top surface 105a of the peripheral region 105. In addition, it makes the bottom surface 104a of the transparent window 104 coplanar with the bottom surface 105b of the polishing layer 120. The top surface 104a of the window 104 and the top surface 105a of the peripheral portion are recessed from the top polishing surface 110 by a distance c. The peripheral portion may be formed of the polishing material 101. The top surface 105a of the peripheral portion may form a protrusion having a width dimension d. Advantageously, dimension "d" (peripheral portion or protrusion width) is greater than or equal to dimension "a" (polishing layer thickness) minus dimension "c" (window recess depth) or window thickness to reduce stress from compressing porous polishing layer 120 adjacent non-porous window 104. Most advantageously, dimension "d" (peripheral portion or protrusion width) is greater than dimension "a" (polishing layer thickness) minus dimension "c" (window recess depth) or window thickness to reduce stress from compressing porous polishing layer 120 adjacent non-porous window 104. Because the window 104 is imperforate, the window has less compressibility on a scale of at least 1mm ² when compressed with a flat circular surface having a thickness equal to the thickness of the window 104.

The polishing pad 100 may include an optional subpad 106 under the polishing layer 120. Subpad 106 also includes an opening 107 having a dimension f that exposes bottom surface 104b of window 104. In fig. 1, dimension f is substantially similar to the dimension of surface 104b to enable light to pass through any portion of the window material.

In fig. 2, the opening 107 has a dimension f that is greater than the bottom surface 104b of the window such that the peripheral portion 105 includes an exposed bottom surface 105b'. Advantageously, dimension "d" (peripheral portion or protrusion width) is greater than or equal to dimension "a" (polishing layer thickness) minus dimension "c" (window recess depth) or window thickness to reduce stress from compressing porous polishing layer 120 adjacent non-porous window 104. Most advantageously, dimension "d" (peripheral portion or protrusion width) is greater than dimension "a" (polishing layer thickness) minus dimension "c" (window recess depth) or window thickness to reduce stress from compressing porous polishing layer 120 adjacent non-porous window 104.

In further examples, as shown in fig. 3, the peripheral portion 105 may include a curved top surface 109, rather than a right angle as shown in fig. 1 and 2. As another alternative, the transition from the top surface 110 to the top peripheral surface 105a of the polishing layer 120 may be an angle other than 90 degrees (i.e., an angled transition rather than a completely vertical transition). A portion of the top surface 104a of the window and the top surface 105a or curved 109 may be coplanar or substantially coplanar. In particular, at least a portion of the top surface 105a or the curved 109 in the region of the side edges of the contact window 104 is coplanar or substantially coplanar with the top window surface 104 a. As used herein, "substantially coplanar" means that the top window surface 104a and the surface of the polishing material in the peripheral region (e.g., 105a or 109) are at a vertical distance from each other of less than 0.02, less than 0.01, or less than 0.005mm.

Fig. 4 and 5 show top views of two examples of polishing pads 100 as disclosed herein, where 110 is the top polishing layer, 102 is an optional recess, 104 is a window and 105 is a peripheral portion of the window area. In fig. 4, the window 105 and window area 103 are substantially rectangular, whereas in fig. 5, the window 105 and window area 103 are elliptical. Other shapes (not shown) may also be used, such as square, circular, other polygons. Further, the top polishing layer may optionally include a plurality of windows (not shown), such as three or more equally spaced windows. Multiple equidistant windows reduce the time between signal measurements. Such reduced time between signal measurements may improve accuracy of polishing endpoint detection.

The thinness of the polishing layer in the peripheral portion of the polishing layer relative to the overall polishing layer thickness may enable flexibility during use without adversely affecting the optical signal (e.g., signal-to-noise ratio remains acceptable) or pad life. Indeed, the recessing of the window area may extend pad life. The depth of the window region recess (e.g., 103) can be adjusted to accommodate the characteristics of the material (e.g., polishing material, window material) used in the pad to provide the desired flexibility without excessive, detrimental deformation during use. Similarly, the width of the peripheral portion may be adjusted to provide the desired mechanical response for the pad material and design. For example, the depression depth c may be greater than 0.1, greater than 0.2, or at least 0.3 millimeters (mm), up to 1.1, up to 1, up to 0.8, or up to 0.6mm. The width d of the peripheral region may be, for example, at least 0.05, at least 0.1, at least 0.2 or at least 0.3 millimeters (mm), up to 1.1, up to 1, up to 0.8 or up to 0.6mm. To further adjust the effective flexibility of the pad, the width f of the opening 107 may be adjusted to controllably vary the flexibility in the window area without affecting the operation of the endpoint system. By removing the subpad 106 from the interface of window 104 and polishing material 101, the stress at the junction can be reduced, further improving window integrity.

The major dimension e of the window material in a direction parallel to the top polished surface may be the size of the window typically used in CMP pads. Further examples, the window has a dimension in a direction parallel to the top polished surface of about 8 to 18mm. The thickness of the window may be less than the overall thickness a of the polishing layer 120 to provide a recess in the window region 103. For example, the thickness of the window may be 0.3 to 3, 0.4 to 2.5, 0.5 to 2mm, or 0.6 to 1.5mm, provided that it is not thicker than the total pad thickness and preferably not thicker than the polishing layer.

The thickness a of the polishing layer can be from 1 up to 4, up to 3, or up to 2.5mm. The total thickness of the polishing pad (e.g., polishing layer plus subpad) is preferably no greater than 4mm. As noted, the polishing layer can include an optional macro-texture (e.g., grooves). Since the macro-texture can affect the effective modulus, the window region recess depth c, the peripheral portion width d can be variably adjusted relative to the macro-texture or groove depth b and the overall polishing layer thickness a to provide the desired flexibility, which is characteristic of the pad designs disclosed herein. For example, the window recess depth c may be 20% to 50%, or 30% to 40%, or 20% to 50%, or 30% to 40% of the overall pad thickness a. As another example, the window recess depth c may be 50% to 90%, or 60% to 80% of the macro texture depth b. As another example, the peripheral portion width d may be 40% to 60% of the macro texture (e.g., groove) width g. These ratios can be easily adjusted during manufacture due to the manufacturing process of the disclosed pad as discussed below.

An additional advantage of the inventive design is that it can provide a simple means for determining the end of pad life. Since the window recess depth may be proportionally lower than the groove depth, pad dressing wear over time is expected to produce a change in endpoint signal as the window recess depth approaches zero. Since such a change may occur before the macro-texture is completely removed, the pad may be stopped before a significant change in polishing performance occurs, so that non-uniformity and defects may be prevented.

The polishing material 101 of the polishing layer 120 can comprise a polymer. The polishing material 101 at the thickness of the polishing layer 120 may be opaque. The pores may be provided, for example, by the addition of hollow flexible polymeric elements (e.g., hollow microspheres), foaming agents, or supercritical carbon dioxide. Examples of polymeric materials for the polishing layer include: polyurethanes, polycarbonates, polysulfones, nylons, polyethers, polyesters, polystyrenes, acrylic polymers, polymethyl methacrylates, polyvinylchlorides, polyvinylfluorides, polyethylenes, polypropylenes, polybutadienes, polyethylenimines, polyethersulfones, polyamides, polyetherimides, polyketones, epoxy resins, silicones, copolymers thereof (such as polyether-polyester copolymers), and combinations or blends thereof. The polishing layer can comprise a polymer that is a polyurethane formed by the reaction of one or more polyfunctional isocyanates and one or more polyols. For example, polyisocyanate-terminated urethane prepolymers may be used. The polyfunctional isocyanate used to form the polishing layer of the chemical mechanical polishing pad of the invention may be selected from the group consisting of: aliphatic polyfunctional isocyanates, aromatic polyfunctional isocyanates and mixtures thereof. For example, the polyfunctional isocyanate used to form the polishing layer of the chemical mechanical polishing pad of the 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; toluidine diisocyanate; para-phenylene diisocyanate; xylylene diisocyanate; isophorone diisocyanate; hexamethylene diisocyanate; 4,4' -dicyclohexylmethane diisocyanate; cyclohexane diisocyanate; and mixtures thereof. The polyfunctional isocyanate may 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 12wt%, 2 to 10wt%, 4-8wt%, or 5 to 7wt% 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); a polycarbonate polyol; a polyester polyol; polycaprolactone polyol; mixtures thereof; and mixtures thereof with one or more low molecular weight polyols selected from the group consisting of: ethylene glycol; 1, 2-propanediol; 1, 3-propanediol; 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; tripropylene glycol. For example, the prepolymer polyol may be selected from the group consisting of: polytetramethylene ether glycol (PTMEG); ester-based polyols (e.g., ethylene glycol adipate, butylene glycol adipate); polypropylene ether glycol (PPG); polycaprolactone polyol; 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 unreacted isocyanate (NCO) concentration of the isocyanate-terminated urethane prepolymer may be 2 to 10% by weight (more preferably 4 to 8% by weight; most preferably 6 to 7% by weight). Examples of commercially available PTMEG-based isocyanate-terminated urethane prepolymers includePrepolymers (available from U.S. department of Italian Co (COIM USA, inc.), such as PET-80A, PET-85A, PET-90A, PET-93A, PET-95A, PET-60D, PET-70D, PET-75D); Prepolymers (available from kopoly (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、LF750D、LF751D、LF752D、LF753D and L325); prepolymers (available from anderson development company (Anderson Development Company), such as 70APLF, 80APLF, 85APLF, 90APLF, 95APLF, 60DPLF, 70APLF, 75 APLF). When the prepolymer polyol is PPG, the unreacted isocyanate (NCO) concentration of the isocyanate-terminated urethane prepolymer may be 3 to 9wt% (more preferably 4 to 8wt%; most preferably 5 to 6 wt%). Examples of commercially available PPG-based isocyanate-terminated urethane prepolymers include Prepolymers (available from U.S. Corp., such as PPT-80A, PPT-90A, PPT-95A, PPT-65D, PPT-75D); Prepolymers (available from koku poly, such as LFG 963A, LFG 964A, LFG D); and Prepolymers (available from anderson development, such as 8000APLF, 9500APLF, 6500DPLF, 7501 DPLF). 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 wt%. Isocyanate-terminated urethane prepolymers based on non-TDI may also be used. For example, isocyanate-terminated urethane prepolymers include those formed by reacting 4,4' -diphenylmethane diisocyanate (MDI) with a polyol such as polytetramethylene glycol (PTMEG) and optionally a glycol such as 1, 4-Butanediol (BDO). When such isocyanate-terminated urethane prepolymers are used, the concentration of unreacted isocyanate (NCO) is preferably 4 to 10wt% (more preferably 4 to 10wt%, most preferably 5 to 10 wt%). Examples of commercially available isocyanate-terminated urethane prepolymers in this class includePrepolymers (available from Usco, inc., such as 27-85A, 27-90A, 27-95A); Prepolymers (available from anderson development, such as IE75AP, IE80AP, IE 85AP, IE90AP, IE95AP, IE98 AP); and Prepolymers (available from koku poly, such as B625, B635, B821).

Window 104 may comprise a desired polymer or polymer blend, so long as it is sufficiently transmissive at the wavelengths used for optical metrology. This may be helpful if the hardness or coefficient of thermal expansion of the window material is similar to that of the material used in the polishing layer. Examples of window materials include polyurethane, acrylic polymers, cyclic olefin copolymers (e.g., TOPAS 8007, etc.). The use of polyurethane materials may be useful in pads where the polishing layer and one or more subpad layers are also polyurethane. The window is advantageously made of a material containing aliphatic polyisocyanates ("prepolymer"). The prepolymer is the reaction product of an aliphatic polyisocyanate (e.g., a diisocyanate) and a hydroxyl containing material. The prepolymer is then cured with a curing agent. Preferred aliphatic polyisocyanates include, but are not limited to, methylenebis 4,4' cyclohexyl isocyanate, cyclohexyldiisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, propylene-1, 2-diisocyanate, tetramethylene-1, 4-diisocyanate, 1, 6-hexamethylene diisocyanate, dodecane-1, 12-diisocyanate, cyclobutane-1, 3-diisocyanate, cyclohexane-1, 4-diisocyanate, 1-isocyanato-3, 5-trimethyl-5-isocyanatomethylcyclohexane, methylcyclohexylene diisocyanate, triisocyanate of hexamethylene diisocyanate, triisocyanates of 2, 4-trimethyl-1, 6-hexane diisocyanate, dimers of hexamethylene diisocyanate, ethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate and mixtures thereof. Preferred aliphatic polyisocyanates have less than 10% by weight of unreacted isocyanate groups.

Advantageously, the curing agent is a polydiamine. Preferred polydiamines include, but are not limited to, diethyltoluenediamine ("DETDA"), 3, 5-dimethylthio-2, 4-toluenediamine and isomers thereof, 3, 5-diethyltoluene-2, 4-diamine and isomers thereof such as 3, 5-diethyltoluene-2, 6-diamine, 4' -bis- (sec-butylamino) -diphenylmethane, 1, 4-bis- (tert-butylamino) -benzene, 4' -methylene-bis- (2-chloroaniline), 4' -methylene-bis- (3-chloro-2, 6-diethylaniline) ("MCDEA"), polytetramethylene oxide-bis-p-aminobenzoate, N, n '-dialkyldiaminodiphenyl methane, p, p' -methylenedianiline ("MDA"), m-phenylenediamine ("MPDA"), methylene-bis 2-chloroaniline ("MBOCA"), 4 '-methylene-bis- (2-chloroaniline) ("MOCA"), 4' -methylene-bis- (2, 6-diethylaniline) ("MDEA"), 4 '-methylene-bis- (2, 3-dichloroaniline) ("MDCA"), 4' -diamino-3, 3 '-diethyl-5, 5' -dimethyldiphenylmethane, 2',3,3' -tetrachlorodiaminodiphenylmethane, trimethylene glycol di-p-aminobenzoate, and mixtures thereof. Preferably, the curing agent of the present invention includes 3, 5-dimethyl-thio-2, 4-toluenediamine and isomers thereof. Suitable polyamine curing agents include both primary and secondary amines.

In addition, other curing agents such as diols, triols, tetrols, or hydroxyl-terminated curing agents may be added to the polyurethane compositions described above. Suitable diol, triol and tetrol groups include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, lower molecular weight polytetramethylene ether glycols, 1, 3-bis (2-hydroxyethoxy) benzene, 1, 3-bis- [2- (2-hydroxyethoxy) ethoxy ] benzene, 1, 3-bis- {2- [2- (2-hydroxyethoxy) ethoxy ] ethoxy } benzene, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, resorcinol-bis- (beta-hydroxyethyl) ether, hydroquinone-bis- (beta-hydroxyethyl) ether, and mixtures thereof. Preferred hydroxyl terminated curing agents include 1, 3-bis (2-hydroxyethoxy) benzene, 1, 3-bis- [2- (2-hydroxyethoxy) ethoxy ] benzene, 1, 3-bis- {2- [2- (2-hydroxyethoxy) ethoxy ] ethoxy } benzene, 1, 4-butanediol, and mixtures thereof. Both the hydroxyl-terminated curing agent and the amine curing agent may contain one or more saturated, unsaturated, aromatic, and cyclic groups. In addition, the hydroxyl-terminated curing agent and the amine curing agent may contain one or more halogen groups. The polyurethane composition may be formed with a blend or mixture of curing agents. However, if desired, the polyurethane composition may be formed with a single curing agent.

Subpad 106 may comprise a polymeric material. The subpad material may be more compliant than the polishing material 101 of the polishing layer 102. Subpad 106 may comprise a porous layer. Examples of polymeric materials for the subpad layer(s) include: polyurethanes, polycarbonates, polysulfones, nylons, epoxies, polyethers, polyesters, polystyrenes, acrylic polymers, polymethyl methacrylates, polyvinylchlorides, polyvinylfluorides, polyethylenes, polypropylenes, polybutadienes, polyethylenimines, polyethersulfones, polyamides, polyetherimides, polyketones, silicones, copolymers thereof (e.g., polyether-polyester copolymers), and combinations or blends thereof.

Polishing pad 100 as disclosed herein can be manufactured by providing a plug of window material in a mold and molding a polishing layer around the plug. According to one method, a thick plate of polishing layer with thick plugs is formed and then cut into polishing layer 120 of desired thickness a. The recess of window region 103 is then cut into polishing layer 120 in the region around the window material plug. The polishing layer may also be cut to provide the macro-texture 102. Alternatively, a single pad may be cast around the window material 104 in a mold having the desired polishing layer of depth a. When cast around the window material, the polishing pad material penetrates the irregular or roughened surface of the window to provide a firm bond, allowing additional processing, such as scraping the polymer cake into a polishing pad. After removal from the mold, the recess is then cut into the polishing layer in the window region to the desired recess depth c to form window region 103. In this latter approach, the macro-texture 102 may be formed from the top surface of the mold, or the flat top surface may be cut again to provide the macro-texture. The cutting may be performed, for example, by milling to form the recess. A commercially available example of a milling machine that may be used may be a CNC milling machine.

A method of using a polishing pad 100 as disclosed herein includes providing a substrate to be polished, providing the polishing pad 100 as disclosed herein, optionally providing a slurry on the polishing pad, contacting the polishing pad with the substrate and moving the substrate and the polishing pad relative to one another (e.g., in a rotational motion), and transmitting light through the transparent window 104 and detecting light reflected back from the substrate through the transparent window 104 to determine when polishing is complete. Preferably, a translucent slurry is used.

The present disclosure further encompasses the following aspects.

Aspect 1: a polishing pad for chemical mechanical polishing comprising a polishing layer having a top polishing surface, a bottom surface, and a thickness, the polishing layer comprising a porous polishing material and a window region, wherein the window region comprises a transparent window having an exposed top surface and an exposed bottom surface to enable transmission of light through the polishing pad in the window region, the exposed top surface of the transparent window being recessed from the top polishing surface, the transparent window extending from the recessed region to the bottom surface of the polishing pad, the window region further comprising a peripheral portion of the polishing material in contact with a side edge of the transparent window, the peripheral portion of the polishing material having a top surface recessed from the top surface of the top polishing surface, and wherein the transparent window is non-porous, and wherein a portion of the top surface adjacent to the peripheral portion of the transparent window is coplanar with the top surface of the transparent window, and wherein the exposed bottom surface of the transparent window is coplanar with the bottom surface of the polishing layer.

Aspect 2: the polishing pad of aspect 1, wherein no chemical bond exists between the transparent window and the polishing layer.

Aspect 3: the polishing pad of aspect 1 or 2, wherein the top polishing surface comprises a macro-texture.

Aspect 4: the polishing pad of aspect 3, wherein the macro-texture comprises grooves.

Aspect 5: the polishing pad of aspect 4, wherein the groove intersects the peripheral portion of the window region.

Aspect 6: the polishing pad of any preceding aspect, further comprising a subpad adjacent the polishing layer and opposite the top polishing surface, wherein the subpad comprises an opening in the window region to enable light transmission through the transparent window.

Aspect 7: the polishing pad of aspect 1, wherein the width of the peripheral portion is greater than or equal to the thickness of the transparent window.

Aspect 8: the polishing pad of aspect 1, wherein the width of the peripheral portion is greater than the thickness of the transparent window.

Aspect 9: the polishing pad of any preceding aspect, wherein the top surface of the transparent window is recessed below the polishing surface by a depth of 0.1 to 1.1, preferably 0.2 to 1, more preferably 0.2 to 0.8, and most preferably 0.3 to 0.6 mm.

Aspect 10: the polishing pad of any preceding aspect, wherein the width of the recessed peripheral portion of the polishing material is 0.05 to 1.1, preferably 0.1 to 1, more preferably 0.2 to 0.8, and most preferably 0.3 to 0.6mm.

Aspect 11: the polishing pad of any preceding aspect, wherein a top surface of the transparent window is coplanar with a top surface of the recessed peripheral portion of the polishing material at a point of contact between the window and the recessed peripheral portion of the polishing material.

Aspect 12: the polishing pad of any preceding aspect, wherein a top surface of the transparent window is coplanar with a top surface of the recessed peripheral portion of the polishing material.

Aspect 13: a method of forming the polishing pad of any one of the preceding aspects, comprising placing a plug of transparent window material in a mold and forming the polishing layer around the plug, cutting a portion of the polishing layer to form a window region comprising the recessed window and a recessed peripheral portion of the polishing material.

Aspect 14 the method of aspect 13, wherein the forming comprises forming a slab cut into a plurality of polishing layers, each polishing layer having transparent window material through a thickness, and the ablating comprises removing a top portion of the transparent window material.

Aspect 15. A method of polishing includes providing a substrate to be polished; providing a polishing pad according to any one of the preceding aspects; providing a translucent slurry over the polishing pad; moving the substrate relative to the polishing pad; light is transmitted through the transparent window material and light reflected back from the substrate through the transparent window and translucent slurry is detected to determine when polishing is complete.

All ranges disclosed herein include endpoints, and endpoints can be combined independently of each other (e.g., ranges of "up to 25wt.%, or more specifically 5wt.% to 20 wt.%) include endpoints and all intermediate values within the range of" 5wt.% to 25wt.%, "etc.). Further, the upper and lower limits may be combined to form a range (e.g., "at least 1 or at least 2 weight percent" and "up to 10 or 5 weight percent" may be combined to form a range of "1 to 10 weight percent", or "1 to 5 weight percent", or "2 to 10 weight percent", or "2 to 5 weight percent").

The present disclosure may alternatively comprise, consist of, or consist essentially of any of the suitable components disclosed herein. The present disclosure may additionally or alternatively be formulated so as to be free of, or substantially free of, any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function or objectives of the present disclosure.

All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or abuts against a term in the incorporated reference, then the term from the present application takes precedence over the conflicting term from the incorporated reference.

Unless stated to the contrary herein, all test criteria are the most recent criteria that are valid by the date of application of the present application or by the date of application of the earliest priority application in which the test criteria appear if priority is required.

Claims

1. A polishing pad for chemical mechanical polishing comprising a polishing layer having a top polishing surface, a bottom surface, and a thickness, the polishing layer comprising a porous polishing material and a window region, wherein the window region comprises a transparent window having an exposed top surface and an exposed bottom surface to enable transmission of light through the polishing pad in the window region, the exposed top surface of the transparent window being recessed from the top polishing surface, the transparent window extending from the recessed region to the bottom surface of the polishing pad, the window region further comprising a peripheral portion of the polishing material in contact with a side edge of the transparent window, the peripheral portion of the polishing material having a top surface recessed from a top surface of the top polishing surface, and wherein the transparent window is non-porous, and wherein a portion of the top surface adjacent the peripheral portion of the transparent window is coplanar with the top surface of the transparent window, and wherein the exposed bottom surface of the transparent window is coplanar with the bottom surface of the polishing layer.

2. The polishing pad of claim 1, wherein there is no chemical bond between the transparent window and the polishing layer.

3. The polishing pad of claim 1, wherein the top polishing surface comprises grooves.

4. The polishing pad of claim 3, wherein the grooves intersect the peripheral portion of the window region.

5. The polishing pad of claim 1, further comprising a subpad adjacent to the polishing layer and opposite the top polishing surface, wherein the subpad comprises an opening in the window region to enable light to be transmitted through the transparent window.

6. The polishing pad of claim 1, wherein the width of the peripheral portion is greater than or equal to the thickness of the transparent window.

7. The polishing pad of claim 1, wherein the width of the peripheral portion is greater than the thickness of the transparent window.

8. A method of forming a polishing pad as recited in claim 1, comprising placing a plug of transparent window material in a mold and forming the polishing layer around the plug,

A portion of the polishing layer is cut away to form the window region including the recessed window and the recessed peripheral portion of the polishing material.

9. The method of claim 7, wherein the forming comprises forming a slab cut into a plurality of polishing layers, each polishing layer having a transparent window material through a thickness, and the ablating comprises removing a top portion of the transparent window material.

10. A method of polishing, comprising

Providing a substrate to be polished

Providing a polishing pad as recited in claim 1

A translucent slurry is provided over the polishing pad,

The substrate is moved relative to the polishing pad,

Light is transmitted through the transparent window material and light reflected back from the substrate through the transparent window and translucent slurry is detected to determine when polishing is complete.