Polishing Pad Using Polyamine and Cyclohexanedimethanol Curing Agent

Abstract

A chemical mechanical polishing pad having a thermoset polyurethane polishing layer includes an isocyanate-terminated urethane prepolymer, a polyamine curing agent, and a cyclohexanedimethanol curing agent, wherein the polyamine curing agent and the cyclohexanedimethanol curing agent are present in a molar ratio of polyamine curing agent to cyclohexanedimethanol curing agent ranging from about 20:1 to about 1:1.

Description

Technical Field

[0001] Cross - reference to Related Applications None

[0002] The disclosed embodiments relate to polishing pads, and more particularly, to thermosetting polyurethane polishing pads comprising isocyanate - terminated urethane prepolymers and polyamine cyclohexanedimethanol hardener mixtures for use in chemical - mechanical polishing (CMP) operations.

Background Art

[0003] Chemical - mechanical planarization, or chemical - mechanical polishing (CMP), is a common technique used to planarize or polish workpieces such as semiconductor wafers. In conventional CMP operations, the wafer is mounted on a carrier (polishing head), and the carrier is placed in contact with a polishing pad of a CMP apparatus (polishing tool). The carrier assembly applies a controllable force to the wafer, pressing the wafer against the polishing pad. A chemical - mechanical polishing composition (e.g., slurry) is dispensed onto the surface of the pad (polishing layer) while the substrate and the pad are being moved relative to each other (e.g., rotated). The wafer surface is polished and planarized by the chemical and mechanical action of the polishing layer and the polishing composition on the surface.

[0004] In both front - end - of - the - line (FEOL) and back - end - of - the - line (BEOL) processing of semiconductor devices, many chemical - mechanical polishing (CMP) operations are used. For example, the following CMP operations are commonly used. Shallow trench isolation (STI) is an FEOL process used before the formation of transistors, in which a pattern of tetraethyl orthosilicate (TEOS) of inlaid is formed on a silicon wafer. Tungsten plugs and interconnects and copper interconnects and dual - damascene processes are BEOL processes used to form a network of metal wires connecting device transistors.

[0005] Commercially available CMP polishing pads are typically manufactured from polyurethane materials (such as thermosetting polyurethane and thermoplastic polyurethane). As is known to those skilled in the art, there are difficult trade - offs when designing and selecting CMP polishing pads. In many CMP applications, polishing pads made of harder materials tend to exhibit higher removal rates, better planarization efficiency, and longer effective pad life than those made of softer materials. However, harder pads also tend to impart more defects (such as scratches) on the wafer surface than softer pads. Such defects can be costly as they may negatively impact product yield. Many CMP operations overcome this challenge by implementing at least two polishing steps: a first step using a harder pad to achieve high throughput and good planarization efficiency (due to a higher removal rate), and a second step using a softer pad to remove the defects imparted in the first step. Such operations can be practical, but tend to be costly in that additional polishing steps are required. There remains an industry need for a polishing pad that can achieve high removal rates, excellent planarization efficiency, long pad life, and a reduced defect rate. Currently available pads generally lack at least one of these categories.

Summary of the Invention

[0006] A chemical mechanical polishing pad comprising a thermosetting polyurethane polishing layer is disclosed. The polishing layer includes an isocyanate - terminated urethane prepolymer, a polyamine curing agent, and a cyclohexanedimethanol curing agent, and the polyamine curing agent and the cyclohexanedimethanol curing agent are present in a molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent in the range of about 20:1 to about 1:1.

[0007] The disclosed pad can provide various advantages, including, for example, both good planarization efficiency and a low defect rate. The disclosed pad can further provide a high removal rate and a long pad life.

Brief Description of the Drawings

[0008] To more fully understand the disclosed subject matter and its advantages, reference is made to the following description taken in conjunction with the accompanying figures.

[0009]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3

DETAILED DESCRIPTION OF THE INVENTION

[0010] A chemical mechanical polishing pad including a thermosetting polyurethane polishing layer is disclosed. The polishing layer includes, consists of, or consists essentially of a curing agent mixture including an isocyanate-terminated urethane prepolymer, a polyamine curing agent, and a cyclohexanedimethanol curing agent. The curing agent mixture includes from about 5 to about 50 mole percent cyclohexanedimethanol curing agent.

[0011] The present invention relates to a chemical mechanical polishing pad comprising a thermosetting polyurethane polishing layer intended to provide both good planarization efficiency and a low defect rate. The polishing pad of the present invention is applicable to the polishing of a wide variety of semiconductor wafers used in the manufacture of integrated circuits and other microdevices. Such wafers can be of conventional node configurations, such as those of 90 nm, 80 nm, 65 nm, 55 nm, 45 nm, 40 nm, or lower technology nodes. However, in some embodiments, the polishing pad of the present invention may be particularly well-suited for advanced node applications (e.g., 28 nm, 22 nm, 20 nm, 16 nm, 14 nm, 10 nm, or lower technology nodes). It will be appreciated that as the node technology becomes more advanced (smaller), the removal of defects induced by polishing becomes more important and the requirements for planarization efficiency become more stringent. For the improved planarization efficiency and defect performance provided, the disclosed polishing pad may be particularly well-suited for advanced node applications. However, as noted above, the polishing pad of the present invention is not limited to use with advanced node wafers, nor is it limited to the characterization of wafers as conventional or advanced nodes. Of course, the pads of the present invention can be used to polish substantially any wafer or workpiece as needed.

[0012] Thermosetting polyurethane (TSU) pads are widely used in the field of chemical mechanical polishing (CMP). For example, IC1000® pads (available from DuPont) and NexPlanar® brand pads (available from Cabot Microelectronics) are commercially available TSU pads. Thermoplastic polyurethane (TPU) pads are also used in commercial CMP operations. For example, Epic® brand pads (available from Cabot Microelectronics) are commercially available TPU pads. TSU pads can provide superior conditioning and pad life compared to equivalent TPU pads (perhaps due to the extensive chemical cross-linking of the TSU material). On the other hand, TPU pads generally provide superior defect performance compared to TSU pads (perhaps due to the viscous properties of the TPU material, e.g., softening of the TPU material at high polishing temperatures).

[0013] As is known to those skilled in the art, polishing pads are generally characterized based on the mechanical properties of the bulk of the pad. For example, polishing pads are generally characterized based on the hardness of the pad (e.g., Shore D hardness) and / or the storage modulus (E’) of the pad (e.g., based on dynamic mechanical analysis). Hard pads are generally thought to promote good planarization efficiency, and soft pads are generally thought to promote good defect performance.

[0014] The present invention is based, at least in part, on the surprising and unexpected discovery that the use of a hardener mixture in which a portion of the polyamine hardener is replaced with cyclohexanedimethanol (CHDM) can result in a thermosetting polyurethane polishing pad that combines the advantages of TSU and TPU polishing pads. CHDM is thought to form urethane bonds with isocyanate-terminated urethane prepolymers, thereby providing improved viscoelastic properties (e.g., softening of the polyurethane obtained at the polishing temperature). The resulting polishing pads have been observed to provide improved planarization efficiency, improved defect performance, and improved conditioning in various CMP applications.

[0015] As is known to those skilled in the art, commercially available polishing pads are generally conditioned during a CMP operation. During such conditioning, the pad is polished, for example, using a diamond lapping conditioning disk. Conditioning is thought to abrade and roughen the pad surface, thereby forming surface irregularities that engage the wafer surface during the CMP operation. One aspect of the present invention was the recognition that the use of the above-described hardener blend containing a polyamine hardener and CHDM may make it possible to achieve an advantageous balance between the bulk pad properties and the properties of the surface irregularities during the CMP operation. For example, the use of a mixed polyamine CHDM hardener can result in a thermosetting polishing pad in which the bulk pad tends to be hard and rigid, promoting planarization efficiency, and the surface irregularities tend to be relatively soft at the polishing temperature (soft relative to the bulk pad), promoting a low defect rate.

[0016] The pad of the present invention includes a polishing layer manufactured by combining a urethane prepolymer and a curing agent to form a thermosetting polyurethane. The urethane prepolymer is an isocyanate-terminated urethane prepolymer that can be prepared by reacting a polyfunctional aromatic isocyanate and a prepolymer polyol. Examples of polyfunctional aromatic isocyanates can include toluene diisocyanate (TDI) compounds such as 2,4-TDI, 2,6-TDI, and mixtures thereof; methylene diphenyl diisocyanate (MDI) compounds such as 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI (also known in the art as 4,4'-diphenylmethane diisocyanate) and mixtures thereof, naphthalene-1,5-diisocyanate, tolidine diisocyanate, para-phenylene diisocyanate, xylylene diisocyanate, and mixtures thereof. The prepolymer polyol can include substantially any suitable diol, polyol, polyol-diol, as well as copolymers and mixtures thereof. For example, the prepolymer polyol can be selected from the group consisting of, including, consisting of, or essentially consisting of polytetramethylene ether glycol (PTMEG), polypropylene ether glycol (PPG), PTMEG or PPG capped with ethylene oxide, polycaprolactone, ester-based polyols such as ethylene or butylene adipate, their copolymers and their mixtures. It will be understood that suitable polyols such as PTMEG and PPG can be mixed with low molecular weight polyols including 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, tripropylene glycol and mixtures thereof.

[0017] Urethane prepolymers are often characterized by the weight percentage of unreacted isocyanate groups (NCO) present in the prepolymer. The weight percentage NCO can be used to determine the mixing ratio of the components for manufacturing polyurethane materials. In a preferred embodiment, the polyfunctional aromatic diisocyanate includes TDI, MDI, or a mixture thereof, and the prepolymer polyol includes PTMEG, PPG, or a mixture thereof. In such an embodiment, the isocyanate-terminated urethane prepolymer can have a weight percentage NCO within the range of about 6.0 to about 20.0 weight percent, for example, within the range of about 7.0 to about 12.0 weight percent.

[0018] In certain embodiments, commercially available isocyanate-terminated urethane prepolymers can be advantageously used. Suitable commercially available prepolymers include, for example, DESMODUR® prepolymers (manufactured by Covestro), Andur® prepolymers (manufactured by Anderson Development Company), Adiprene® prepolymers (manufactured by Chemtura), and Imuthane® prepolymers (manufactured by COIM USA, Inc.). Suitable prepolymers can include, for example, PET-70D, PHP-70D, PET-75D, PHP-75D, PPT-75D, PHP-80D, LFG-740D, LF-650D, LF-700D, LF-750D, LF-751D, LF-753D, 60DPLF, 70DP, 70DPLF, 7DPLM, 7201DPLF, 73DPLF, 7-5DPLF, 1-75DP, 2-72DP, 75DGP-2, 7500DP, 75DPLF, 7500DP, 7501DP, 80DPLF, 81DP, 82DGP, IP89, LU-T60D, LU-T70D, LU-T75D, MAX T-80, MD15120.

[0019] One of ordinary skill in the art will readily understand that commercially available prepolymers are generally classified using a hardness scale (which generally correlates with the hardness of the corresponding polyurethane reaction product). For example, Imuthane® PET-70D and PHP-70D, Adiprene® LF700D, Andur® 70DP and 70DPLF may be referred to as 70D prepolymers, which exhibit a corresponding hardness of 70 on the Shore D hardness scale. Similarly, Imuthane® PET-75D, PHP-75D, and PPT-75D, Adiprene® LF750D, LF751D, and LF753D, Andur® 75DGP-2, 75DPLF, 7500DP, and 7501DP, and DESMODUR® LU-T75D may be referred to as 75D prepolymers, which exhibit a corresponding hardness of 75 on the Shore D hardness scale. Also, Imuthane® PHP-80D and Andur® 80DPLF may be referred to as 80D prepolymers, which exhibit a corresponding hardness of 8 of 0 on the Shore D hardness scale.

[0020] In a preferred embodiment, a hard prepolymer is used. By "hard" is meant that the prepolymer can be classified as having a Shore D hardness value of about 70 or greater (e.g., about 75 or greater). Suitable hard prepolymers can have a Shore D hardness in the range of about 70 to about 85 (e.g., about 75 to about 85 or about 75 to about 80). Hard prepolymers can include, for example, 70D, 75D, and 80D prepolymers (e.g., 75D and 80D prepolymers), such as those listed in the previous paragraph, although of course the disclosed embodiments are not limited in this regard. Suitable prepolymers can also include mixtures of two or more commercially available prepolymers, such as a mixture of a 70D prepolymer and a 75D prepolymer, a mixture of a 75D prepolymer and an 80D prepolymer, or a mixture of a 70D prepolymer and an 80D prepolymer.

[0021] As described above, the pad of the present invention includes an abrasive layer produced by combining at least one urethane prepolymer (e.g., including at least one rigid prepolymer) and a curing agent to form a thermosetting polyurethane. Embodiments of the disclosed abrasive pads use first and second curing agents (e.g., a mixed or blended curing agent composition including the first and second curing agents) including a first polyamine curing agent and a second cyclohexanedimethanol (CHDM) curing agent.

[0022] The polyamine curing agent can include substantially any suitable polyamine, including, for example, diamines and other polyfunctional amines. The polyamine curing agent may be a low molecular weight polyamine curing agent. By low molecular weight is meant that the polyamine curing agent has a molecular weight of less than 1000 g / mol (e.g., less than 700 g / mol, less than 500 g / mol, or less than 300 g / mol).

[0023] Exemplary diamines can include aniline diamine compounds, toluene diamine compounds, aminobenzoate compounds, and mixtures thereof. Exemplary aniline diamine compounds include 4,4'-methylenebis(2-chloroaniline) (MBCA or MOCA); 4,4'-methylene-bis-o-chloroaniline (MbOCA); 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) (MCDEA); 4,4'-methylene-bis-aniline; and 1,2-bis(2-aminophenylthio)ethane. Exemplary toluene diamine compounds include dimethylthiotoluene diamine; diethyltoluene diamine; 5-tert-butyl-2,4- and 3-tert-butyl-2,6-toluene diamine; 5-tert-amyl-2,4- and 3-tert-amyl-2,6-toluene diamine; and chlorotoluene diamine. Exemplary aminobenzoate compounds include trimethylene glycol di-p-aminobenzoate; polytetramethylene oxide di-p-aminobenzoate; polytetramethylene oxide mono-p-aminobenzoate; polypropylene oxide di-p-aminobenzoate; and polypropylene oxide mono-p-aminobenzoate.

[0024] Aniline diamine compounds such as 4,4-methylenebis(2-chloroaniline), and toluenediamine compounds such as dimethylthiotoluenediamine are preferred (however, the disclosed embodiments are not clearly limited in this regard). Such diamine compounds are commercially available, for example, from Albemarle Corporation, Makro Chemical, Gantrade Corporation, and Evonik.

[0025] Cyclohexanedimethanol (CHDM) hardener (generally also called 1,4-cyclohexanedimethanol and 1,4-bis(hydroxymethyl)cyclohexane) is a disubstituted derivative of cyclohexane and is classified as a diol (having two OH groups). The chemical formula of CHDM is C6H 10 (CH2OH)2, and cis and trans stereoisomers are known. Commercially available CHDM is generally a mixture of the cis and trans isomers. The disclosed embodiments are not limited to any particular CHDM isomer or any particular isomer ratio such as the ratio of the cis and trans isomers.

[0026] Although not wishing to be bound by theory, CHDM is thought to act as a mild softening agent. Replacing a portion of the polyamine hardener with CHDM (to form a hardener mixture) is thought to result in the formation of urethane bonds between the diisocyanate and CHDM rather than urea bonds between the diisocyanate and the polyamine. The use of an appropriate ratio of polyamine hardener to CHDM has been found to result in a pad having the above balance, where the bulk pad tends to be hard and rigid and promotes planarization efficiency, and the surface irregularities tend to be relatively soft at the polishing temperature (e.g., a temperature within the range of about 50 to about 80 °C) and promote a low defect rate. If too much CHDM is used (low ratio of polyamine to CHDM), the pad tends to be a soft pad with insufficient bulk rigidity, and if too little CHDM is used (high ratio of polyamine to CHDM), the pad tends to be a hard pad and the surface irregularities are not soft enough at the polishing temperature. Further, the preferred ratio of polyamine hardener to CHDM can depend on the hardness of the isocyanate-terminated prepolymer, and it has also been found that a harder prepolymer may require more CHDM (lower ratio) to achieve the above property balance. The preferred ratio of polyamine hardener to CHDM can also depend on the CMP application and specific CMP conditions (downforce, platen speed, slurry flow rate, etc.).

[0027] The first and second curing agents (polyamine and CHDM curing agent) are preferably used in a molar ratio of polyamine curing agent to CHDM curing agent in the range of about 20:1 to about 1:1 (e.g., about 15:1 to about 1:1, about 10:1 to about 1:1, about 9:1 to about 1:1, about 7:1 to about 1.5:1, about 6:1 to about 1.5:1, or about 6:1 to about 2:1). In other words, the first and second curing agents can be considered to form a curing agent mixture (or blend) that comprises, consists of, or consists essentially of a polyamine curing agent and a CHDM curing agent. The curing agent mixture preferably comprises about 5 to about 50 mole percent (e.g., about 10 to about 50 mole percent, about 5 to about 40 mole percent, about 10 to about 40 mole percent, about 12 to about 40 mole percent, about 15 to about 40 mole percent, or about 15 to about 35 mole percent) of the CHDM curing agent.

[0028] It will be understood that the preferred ratio of polyamine curing agent to CHDM curing agent in the curing agent mixture can depend on the choice of prepolymer. For example, if the prepolymer comprises a 75D prepolymer, the curing agent mixture can comprise about 5 to about 35 mole percent (e.g., about 5 to about 30 mole percent, about 5 to about 25 mole percent, about 10 to about 30 mole percent, or about 10 to about 25 mole percent) of CHDM. Similarly, if the prepolymer comprises an 80D prepolymer, the curing agent mixture can comprise about 10 to about 50 mole percent (e.g., about 10 to about 45 mole percent, about 10 to about 40 mole percent, about 15 to about 40 mole percent, or about 15 to about 35 mole percent) of CHDM.

[0029] It will be appreciated that the thermosetting polyurethane polishing layer of the disclosed embodiments of the polishing pad may be porous or non-porous. The porous polishing layer can be prepared, for example, by forming a thermosetting polyurethane foam, by including a soluble porogen in the polyurethane composition, or by including hollow microspheres (such as polymer microspheres) in the polyurethane composition. The porous embodiments can have substantially any suitable porosity in the range of, for example, about 5 to about 60 volume percent (such as about 10 to about 50 volume percent, about 15 to about 50 volume percent, or about 20 to about 40 volume percent). The non-porous embodiments are substantially completely dense and generally have a porosity of less than about 5 volume percent.

[0030] One of ordinary skill in the art will readily appreciate that the porosity of the polishing pad (or the polishing layer within the pad) can be estimated by measuring the apparent density of the pad (or layer). Fully high-density embodiments (i.e., non-porous embodiments) generally have a density of about 1.2 g / cm 3 (such as about 1.15 to about 1.25 g / cm 3 ). Porous embodiments generally have an apparent density of less than about 1.2 g / cm 3 , such as about 0.6 to about 1.14 g / cm 3 (such as about 0.72 to about 1.08 g / cm 3 , about 0.72 to about 1.02 g / cm 3 , or about 0.78 to about 0.96 g / cm 3 ). Of course, the disclosed embodiments are not limited with respect to the apparent density of the pad or the polishing layer.

[0031] As described above, commercially available polishing pads are typically conditioned during CMP operation, thereby forming surface irregularities. These surface irregularities interact with the wafer during CMP operation and can greatly affect the resulting polishing performance. Thus, evaluation of the surface irregularity characteristics can provide an indicator of pad performance.

[0032] The disclosed embodiments are not limited in this regard (except as otherwise specified by specific elements in the claims), and the mechanical properties of the surface irregularities can be estimated, for example, by evaluating the mechanical properties of a substantially completely dense polishing pad coupon made of the same polyurethane material. Without wishing to be bound by theory, it is known that the surface irregularities are, for example, small features on a scale ranging from sub-microns to tens of microns, and are therefore considered to be substantially non-porous. Thus, the mechanical properties of a substantially completely dense pad (e.g., a pad having a porosity of less than about 5 volume percent) can be considered to appropriately represent (or approximate) the mechanical properties of the surface irregularities (the polyurethane matrix material from which the surface irregularities are formed during conditioning).

[0033] Accordingly, the parameter values (and ranges) disclosed below (and in the claims) are based on measurements made on substantially non-porous pad coupon samples having no grooves or other surface features intended to transport or retain slurry during the polishing operation. The measurement methods used to measure the tensile storage modulus (E’), Shore D hardness, and tensile toughness at 25 °C and 75 °C are described in more detail in Examples 2-4 below.

[0034] In certain embodiments, the surface irregularities described above can be characterized based on the ratio of the tensile storage modulus (E’) at 25 °C to the tensile storage modulus at 75 °C, the tensile storage modulus (E’) at 25 °C, the Shore D hardness at 25 °C, and the tensile toughness at 25 °C. For example, the surface irregularities can have a ratio of the tensile storage modulus (E’) at 25 °C to the tensile storage modulus at 75 °C within the range of about 3:1 to about 20:1 (e.g., about 3:1 to about 15:1, about 4:1 to about 15:1, about 4:1 to about 12:1, about 5:1 to about 12:1, or about 5:1 to about 10:1).

[0035] Furthermore, in embodiments where the isocyanate-terminated urethane prepolymer comprises a 75D prepolymer, the surface irregularities can have a tensile storage modulus (E’) at 25 °C that exceeds about 500 MPa (e.g., exceeds about 600 MPa, exceeds about 700 MPa, or exceeds about 800 MPa). In such embodiments that include a 75D prepolymer, the surface irregularities can alternatively and / or additionally have a Shore D hardness at 25 °C that exceeds about 55 (e.g., exceeds about 60, exceeds about 65, or exceeds about 68). These embodiments can further (alternatively and / or additionally) have a tensile toughness at 25 °C that exceeds about 80 MPa (e.g., exceeds about 100 MPa).

[0036] In embodiments where the isocyanate-terminated urethane prepolymer comprises an 80D prepolymer, the surface irregularities can have a tensile storage modulus (E’) at 25 °C that exceeds about 800 MPa (e.g., exceeds about 1000 MPa, exceeds about 1100 MPa, or exceeds about 1200 MPa). In such embodiments that include an 80D prepolymer, the surface irregularities can alternatively and / or additionally have a Shore D hardness at 25 °C that exceeds about 65 (e.g., exceeds about 70, or exceeds about 72). These embodiments can further (alternatively and / or additionally) have a tensile toughness at 25 °C that exceeds about 20 MPa (e.g., exceeds about 40 MPa, or exceeds about 50 MPa).

[0037] The disclosed pads can be manufactured using substantially any suitable pad manufacturing technique, including but not limited to casting, molding, coating, extrusion, printing, sintering, spraying, etc. (Embodiments of the disclosed pads are not limited in this regard). For example, the pads of the present invention can be manufactured using various known molding and casting techniques. Molded polyurethane pads can be particularly suitable for planarizing semiconductor substrates. Such pads can be manufactured individually, for example, by dividing the raw materials into two batches. The first batch of raw materials may include an isocyanate-terminated prepolymer, as well as lubricants and porosity-forming agents, such as certain optional additives including microspheres or gases. The second batch of raw materials may include a curing agent mixture (polyamine and CHDM curing agent), as well as certain other optional additives such as ultraviolet stabilizers. The two batches are prepared separately and then can be blended together at a predetermined blend ratio and temperature. The mixture can then be poured into a mold and maintained at a high temperature, for example, from about 60°C to about 160°C. The mold can optionally be developed within a sealed chamber and exposed to vacuum or pressure to expel the air trapped in the poured blend. After a predetermined time (e.g., about 10 to about 30 minutes), the pad can be removed from the mold and then cured at a temperature within the range of about 30°C to about 100°C for about 6 to 12 hours.

[0038] It will be understood that the present disclosure can include a number of embodiments. These embodiments include, but are not limited to, the following embodiments.

[0039] A first embodiment can include a chemical mechanical polishing pad comprising a thermosetting polyurethane polishing layer, the thermosetting polishing layer including an isocyanate-terminated urethane prepolymer; a polyamine curing agent; and a cyclohexanedimethanol curing agent, the polyamine curing agent and the cyclohexanedimethanol curing agent being present in a molar ratio of polyamine curing agent to cyclohexanedimethanol curing agent within the range of about 20:1 to about 1:1.

[0040] The second embodiment may include the first embodiment in which the prepolymer is a reaction product of a toluene diisocyanate (TDI) compound or a methylene diphenyl diisocyanate (MDI) compound with polytetramethylene ether glycol (PTMEG) or polypropylene ether glycol.

[0041] The third embodiment may include the first or second embodiment in which the prepolymer is an aromatic prepolymer selected from the group consisting of 75D prepolymer, 80D prepolymer, and mixtures thereof.

[0042] The fourth embodiment may include any one of the first to third embodiments in which the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of aniline diamine compounds, toluene diamine compounds, aminobenzoate compounds, and mixtures thereof.

[0043] The fifth embodiment may include the fourth embodiment in which the aromatic diamine curing agent is selected from the group consisting of 4,4 - methylenebis(2 - chloroaniline), dimethylthiotoluenediamine, and mixtures thereof.

[0044] The sixth embodiment may include any one of the first to fifth embodiments in which the molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of about 7:1 to about 1.5:1.

[0045] The seventh embodiment may include any one of the first to sixth embodiments in which the thermosetting polyurethane polishing layer includes surface irregularities, and the surface irregularities have a ratio of the storage modulus at 25°C to the storage modulus at 75°C in the range of about 3 to about 20.

[0046] The eighth embodiment may include the seventh embodiment in which (i) the isocyanate - terminated urethane prepolymer includes a 75D prepolymer, and (ii) the surface irregularities have a storage modulus (E’) at 25°C exceeding about 500 MPa and a Shore D hardness at 25°C exceeding about 60.

[0047] The ninth embodiment may include the eighth embodiment in which the surface irregularities have a tensile toughness at 25°C exceeding about 100 MPa.

[0048] The tenth embodiment may include the seventh embodiment in which (i) the isocyanate-terminated urethane prepolymer includes an 80D prepolymer, and (ii) the surface irregularities have a storage modulus (E') at 25°C exceeding about 1000 MPa and a Shore D hardness at 25°C exceeding about 70.

[0049] The eleventh embodiment may include the tenth embodiment in which the surface irregularities have a tensile toughness at 25°C exceeding about 50 MPa.

[0050] The twelfth embodiment may include any one of the first to eleventh embodiments in which the thermosetting polyurethane polishing layer further includes a sufficient amount of hollow microspheres such that the thermosetting polyurethane polishing layer has a porosity in the range of about 10 to about 50 percent.

[0051] The thirteenth embodiment may include any one of the first to twelfth embodiments in which (i) the prepolymer is an aromatic prepolymer selected from the group consisting of a 75D prepolymer, an 80D prepolymer, and mixtures thereof, (ii) the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof, and (iii) the molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of about 10:1 to about 1.5:1.

[0052] The fourteenth embodiment may include any one of the first to thirteenth embodiments in which the thermosetting polyurethane polishing layer is adhered to the sub-pad.

[0053] The 15th embodiment can include a thermosetting polyurethane polymer polishing layer, and the thermosetting polishing layer is a curing agent mixture including an isocyanate-terminated urethane prepolymer, a polyamine curing agent, and a cyclohexanedimethanol curing agent, the curing agent mixture including about 5 to about 50 mole percent of the cyclohexanedimethanol curing agent.

[0054] The 16th embodiment can include the 15th embodiment, wherein the prepolymer is a reaction product of a toluene diisocyanate (TDI) compound or a methylene diphenyl diisocyanate (MDI) compound and polytetramethylene ether glycol (PTMEG) or polypropylene ether glycol.

[0055] The 17th embodiment can include the 15th or 16th embodiment, wherein the prepolymer is an aromatic prepolymer selected from the group consisting of 75D prepolymer, 80D prepolymer, and mixtures thereof.

[0056] The 18th embodiment can include any one of the 15th to 17th embodiments, wherein the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of aniline diamine compounds, toluene diamine compounds, aminobenzoate compounds, and mixtures thereof.

[0057] The 19th embodiment can include the 18th embodiment, wherein the aromatic diamine curing agent is selected from the group consisting of 4,4-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof.

[0058] The 20th embodiment can include any one of the 15th to 19th embodiments, wherein the curing agent mixture includes about 10 to about 40 weight percent of the cyclohexanedimethanol curing agent.

[0059] The 21st embodiment can include any one of the 15th to 20th embodiments, wherein the curing agent mixture consists of a polyamine curing agent and a cyclohexanedimethanol curing agent.

[0060] Embodiment 22 may include any one of Embodiments 15 to 21, wherein the thermosetting polyurethane polishing layer includes surface irregularities, and the surface irregularities have a ratio of the storage modulus at 25°C to the storage modulus at 75°C within a range of about 3 to about 20.

[0061] Embodiment 23 may include Embodiment 22, wherein (i) the isocyanate-terminated urethane prepolymer includes a 75D prepolymer, and (ii) the surface irregularities have a storage modulus (E') at 25°C exceeding about 500 MPa and a Shore D hardness at 25°C exceeding about 60.

[0062] Embodiment 24 may include Embodiment 23, wherein the surface irregularities have a tensile toughness at 25°C exceeding about 100 MPa.

[0063] Embodiment 25 may include Embodiment 22, wherein (i) the isocyanate-terminated urethane prepolymer includes an 80D prepolymer, and (ii) the surface irregularities have a storage modulus (E') at 25°C exceeding about 1000 MPa and a Shore D hardness at 25°C exceeding about 70.

[0064] Embodiment 26 may include Embodiment 25, wherein the surface irregularities have a tensile toughness at 25°C exceeding about 50 MPa.

[0065] Embodiment 27 may include any one of Embodiments 15 to 26, wherein the thermosetting polyurethane polishing layer further includes a sufficient amount of hollow microspheres such that the thermosetting polyurethane polishing layer has a porosity within a range of about 10% to about 50%.

[0066] Embodiment 28 may include any one of Embodiments 15 to 27, where (i) the prepolymer is an aromatic prepolymer selected from the group consisting of 75D prepolymer, 80D prepolymer, and mixtures thereof; (ii) the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof; (iii) the curing agent mixture includes about 10 to about 40 weight percent of cyclohexanedimethanol curing agent.

[0067] Embodiment 29 may include any one of Embodiments 15 to 28, where the thermosetting polyurethane polishing layer is adhered to the sub-pad.

[0068] Embodiment 30 may include a method for manufacturing a thermosetting polishing pad, the method including: (a) mixing an isocyanate-terminated urethane prepolymer, a polyamine curing agent, and a cyclohexanedimethanol curing agent (the diamine curing agent and the cyclohexanedimethanol curing agent are present in a molar ratio of diamine curing agent to cyclohexanedimethanol curing agent in the range of about 20:1 to about 1:1) to obtain a mixture; (b) heating the mixture in a mold to obtain a pre-cured pad; (c) curing the pre-cured pad to obtain a polishing pad.

[0069] Embodiment 31 may include Embodiment 30, further including (d) machining the polishing pad to remove the formed skin to obtain a polishing pad having a desired thickness.

[0070] Embodiment 32 may include Embodiment 31, further including (e) adhering the polishing pad to the sub-pad to obtain a multi-layer polishing pad.

[0071] The 33rd embodiment may include any one of the 30th to 32nd embodiments, where (i) the prepolymer is an aromatic prepolymer selected from the group consisting of 75D prepolymer, 80D prepolymer, and mixtures thereof; (ii) the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof; and (iii) the molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of about 10:1 to about 1.5:1.

[0072] The 34th embodiment may include a method of chemically mechanical polishing a semiconductor substrate, the method comprising: (a) contacting the substrate with a polishing pad and a polishing composition, where the polishing pad may be selected from any one of the 1st to 29th embodiments; (b) relatively moving the polishing pad with respect to the substrate; and (c) abrading the substrate to remove a portion of a layer from the substrate, thereby polishing the substrate.

[0073] The 35th embodiment may include the 34th embodiment, where (i) the prepolymer is an aromatic prepolymer selected from the group consisting of 75D prepolymer, 80D prepolymer, and mixtures thereof; (ii) the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof; and (iii) the molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of about 10:1 to about 1.5:1.

Examples

[0074] The following examples further illustrate the present invention, but should not be construed as limiting its scope.

[0075] Example 1 To evaluate the effect of CHDM on mechanical properties, several non-porous polishing pad coupons were prepared (described in more detail in Examples 2-4 below). The coupons were prepared by mixing a prepolymer, a diamine hardener, and an optional diol hardener. The mixture was poured into a preheated 9-inch square mold base and compression molded there at 260°F for 10 minutes. The pre-cured pad coupons were then removed from the mold and cured in a vented oven at a temperature of 200°F for 12 hours. The coupons were then cut into samples for mechanical testing.

[0076] Table 1A shows 11 experimental pad coupons 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, and 1K containing various prepolymer / diamine hardener / diol compositions. Each composition in Table 1A contained Imuthane® PET-75D prepolymer and dimethylthiotoluenediamine hardener. The compositions are listed as parts by weight and each composition is normalized to 100 parts by weight of prepolymer. For example, pad coupon 1B contained 100 parts by weight of Imuthane® PET-75D, 18.7 parts by weight of dimethylthiotoluenediamine, and 2.2 parts by weight of CHDM.

[0077] Experimental coupon 1A was a comparison in that it did not contain a diol hardener. Experimental pads 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, and 1K contained various diol hardeners including CHDM (1B and 1C), 2-methyl-1,3-propanediol (PDO) (1D and 1E), 1,4-butanediol (BDO) (1F and 1G), diethylene glycol (DEG) (1H and 1I), and 1,6-hexanediol (HDO) (1J and 1K). The experimental pad coupons contained a molar ratio of diamine to diol of approximately 5.5 to 1 (1B, 1D, 1F, 1H, and 1J) and approximately 2.3 to 1 (1C, 1E, 1G, 1I, and 1K).

Table 1

[0078] Table 1B shows four additional pad coupons 1L, 1M, 1N, and 1O that include Andur® 80DPLF prepolymer, dimethylthiotoluenediamine curing agent, and an optional CHDM curing agent (enumerated in parts by weight as above). Experimental coupon 1L was a comparison in that it did not include the CHDM curing agent. Experimental pad coupons 1M, 1N, and 1O included molar ratios of diamine to CHDM of approximately 5.5 to 1 (1M), approximately 2.3 to 1 (1N), and approximately 1.2 to 1 (1O).

Table 2

[0079] Table 1C shows three additional pad coupons 1P, 1Q, and 1R that include a 50 / 50 mixture of Imuthane® PET-75D and Andur® 80DPLF prepolymer, dimethylthiotoluenediamine curing agent, and an optional CHDM curing agent (enumerated in parts by weight as above). Experimental coupon 1P was a comparison in that it did not include the CHDM curing agent. Experimental pad coupons 1Q and 1R included molar ratios of diamine to CHDM of approximately 9 to 1 (1Q) and approximately 4 to 1 (1R).

Table 3

[0080] Example 2 In this example, the Shore D hardness and density of each of the pad coupons disclosed in Example 1 were measured. The Shore D hardness was measured at 25 °C using a standard durometer hardness test according to the procedures specified in ASTM 2240 and ISO 868. The density was measured using a Mettler Toledo Pycnometer model AG285 or XS205. The samples were cut into circles with a diameter of 1 inch. The samples were replaced with isopropyl alcohol in a wet pycnometer, and the apparent density was measured by gravimetric analysis. Tables 2A, 2B, and 2C list the Shore D hardness values and density values of each of the pad coupons listed in Tables 1A, 1B, and 1C above.

Table 4

Table 5

Table 6

[0081] As is readily apparent in Tables 2A - 2C, the use of the blended diamine diol hardener decreased the hardness of the pad coupons, and the decrease in hardness increased with increasing diol concentration. The decrease in hardness was not highly dependent on the diol composition. It was observed that the pad coupons using the 80D prepolymer were harder than the pad coupons using only the 75D prepolymer. The apparent density of the pad coupons was not substantially affected by the diol composition.

[0082] Example 3 For each of the pad coupons disclosed in Example 1, the storage modulus (E’) was measured as a function of temperature using dynamic mechanical analysis (DMA). The cured pad coupon samples were cut into rectangular specimens of 6 mm × 30 mm and attached to tensile clamps. The physical dimensions of each sample were measured using a micrometer prior to the above DMA test. The measured dimensions were input into the DMA software before attaching the sample to the test chamber. The DMA measurements were performed using a Q800 DMA measurement tool available from TA Instruments. The DMA measurements were conducted in accordance with ASTM D4065. Briefly, the DMA test was performed using the standard multi-frequency controlled strain tensile mode, with a frequency of 1 Hz, an amplitude of 30 microns, a temperature ramp rate of 5 °C per minute from -50 to 180 °C, and in a dry state with an air flow.

[0083] As disclosed in ASTM D4065, it will be readily understood by those skilled in the art that there are numerous sample configurations and vibration deformation modes for performing DMA measurements, including bending, tension, compression, three-point bending, torsion, single cantilever, dual cantilever, and shear deformation. It will be appreciated that there may be certain advantages and disadvantages associated with selecting any one of these vibration deformation modes. Based in part on ease of use and good reproducibility of test results, the DMA measurements disclosed herein utilized vibration tensile deformation as described above.

[0084] Tables 3A, 3B, and 3C list the values of the storage modulus measured at 25 °C and 75 °C, designated as E’(25) and E’(75), respectively, and the corresponding storage modulus ratio E’(25) / E’(75) for each of the pad coupon samples disclosed in Tables 1A, 1B, and 1C, respectively.

Table 7

Table 8

Table 9

[0085] From the data shown in Table 3A, it is readily apparent that the addition of the diol curing agent decreased the storage modulus of the pad coupons and increased the storage modulus ratio. Pad coupons containing CHDM were observed to have the highest storage modulus and the highest storage modulus ratio at 25 °C. As is readily apparent from the data shown in Tables 3B and 3C, pads using an 80D prepolymer have significantly higher storage modulus and lower storage modulus ratio than pads using only a 75D prepolymer.

[0086] Figures 1A, 1B, 2A, and 2B show DMA plots of storage modulus and tan δ versus temperature for pad coupons 1A, 1B, and 1C and pad coupons 1L, 1M, 1N, and 1O. From the DMA plots of Figures 1A, 1B, 2A, and 2B, it is readily apparent that increasing the molar ratio of CHDM to diamine curing agent increases the E’ ratio due to softening at high polishing temperatures and decreases the temperature of the maximum tan δ value. The use of the above-described curing agent blend containing CHDM was observed to result in a hard and rigid thermosetting polishing pad that softens at high polishing temperatures (e.g., in the range of about 60 to about 90 °C). During use (e.g., during a CMP operation), the bulk pad is suitably hard and rigid and can promote good planarization efficiency, while the surface irregularities soften at the polishing temperature and can thus promote a low defect rate.

[0087] Example 4 Tensile toughness and elongation at break were determined for pad coupons 1A, 1B, 1L, 1M, and 1N described in Example 1 above. The pad coupon samples were prepared as described in Examples 1 and 3 above. Each sample was mounted in an Instron 4411 tensile strength tester. Measurements were made in accordance with ASTM D638-98 using a 100-pound load cell and a crosshead speed of 0.2 inches per minute at room temperature.

[0088] Table 4 lists the measured values of tensile toughness and elongation at break for the above-described pad coupons.

Table 10

[0089] As is readily apparent from the data shown in Table 4, the addition of the CHDM curing agent increased both the tensile toughness and the elongation at break. By enhancing toughness and reducing brittleness (increasing the elongation at break), certain embodiments using the CHDM curing agent may exhibit improved conditioning and improved pad life.

[0090] Example 5 A number of polishing pads for CMP testing were fabricated. Each pad was manufactured using a corresponding commercially available prepolymer, dimethylthiotoluenediamine curing agent, optional diol curing agent, and Expancel® 461DE20 pore filler (microspheres). The optional diol curing agent included CHDM or 2-methyl-1,3-propanediol (PDO). The prepolymer was first mixed with the pore filler to achieve a uniform distribution. The dimethylthiotoluenediamine curing agent and the optional diol curing agent were then mixed with the prepolymer / filler blend. The combined mixture was dispensed onto the bottom of a 30-inch diameter mold. The mixture was maintained in the mold at a temperature of 260°F for 10 minutes. The pre-cured pad was then removed from the mold and cured in a vented oven at a temperature of 200°F for 12 hours. The pad compositions are listed as parts by weight and each composition is normalized to 100 parts by weight of prepolymer.

[0091] The as-formed pads, as shown in FIG. 16 of U.S. Patent No. 9,180,570, included 16 sectors, each sector having a formed groove pattern including 18 main grooves. After curing, the pads were surface finished to remove a 0.003 - 0.010 inch mold skin and thinned from the back side to a final thickness of 0.065 inches using computer numerical control (CNC) machining. These top pads (polishing layers) were then laminated with sub pads and platen adhesives. The pads were then ready to be polished with an Applied Materials Reflexion™ polishing tool or cut to a final diameter of 20 inches for an Applied Materials Mirra™ polishing tool.

[0092] Table 5 lists four control pads 5A, 5B, 5G, and 5J that do not contain an optional diol curing agent, and eight experimental pads 5C, 5D, 5E, 5F, 5H, 5I, 5K, and 5L that contain a diol curing agent. The experimental pads 5C - 5F, 5H, 5K, and 5L are pads of the present invention that include a polyamine curing agent to CHDM curing agent molar ratio in the range of about 2.3:1 to about 5.7:1 for the PET75D prepolymer formulation, a molar ratio of about 2.3:1 for the 80DPLF prepolymer formulation, and molar ratios of about 4:1 and about 9:1 for the mixed PET75D / 80DPLF prepolymer formulation. Table 5 shows the mixing ratios of the raw materials in parts by weight for the control pads and the experimental pads, with each pad normalized to 100 parts by weight of prepolymer.

Table 11

[0093] Example 6 The polishing pads 5B and 5C (from Example 5) were evaluated in a CMP experiment where a blanket silicon oxide (TEOS) wafer was polished. A commercially available two-component slurry ACS940 / ACC260 available from KC Tech was used, and the pads were evaluated using a Reflexion® CMP tool (available from Applied Materials). The wafers were polished at a downforce of 3.5 psi, a platen speed of 50 rpm, a head speed of 47 rpm, and a slurry flow rate of 140 ml / min for ACS940 and 160 ml / min for ACC260. The polishing pads were conditioned ex-situ between each wafer using a Saesol® LPX-DS2 conditioner at a downforce of 5 pounds for 12 seconds. A total of 40 TEOS wafers were polished. Each wafer was polished for 1 minute, and the total removal amount of TEOS was converted to a polishing rate in units of Å / min. Also, the polished wafers were evaluated for scratches using a KLA-Tencor® Surfscan® SP2 defect and surface quality inspection system, excluding a 2 mm wafer edge and with a 110 nm cutoff. Table 6 shows the average polishing rate achieved with each pad, as well as the average and maximum number of defects observed with each pad.

Table 12

[0094] As is readily apparent from the polishing data shown in Table 6, pad 5C containing CHDM showed excellent TEOS removal rate and a significant reduction in defects (scratches).

[0095] Example 7 Pads 5A and 5C (from Example 5) were evaluated in a shallow trench isolation (STI) CMP experiment. The pads were evaluated using a Reflexion® CMP tool that uses slurry D7805A / B (available from Cabot Microelectronics Corporation), which was prepared by first combining one part of Pack A with six parts of deionized water and then with three parts of Pack B. A blanket silicon oxide wafer and a Silyb STI patterned wafer were polished at a downforce of 2.0 psi, a platen speed of 93 rpm, a head speed of 87 rpm, and a slurry flow rate of 250 ml / min. The polishing pads were conditioned in situ using a Saesol® DS8051 conditioner at a downforce of 6 pounds. The patterned wafers were polished to an endpoint +100 percent overpolish time. Five silicon oxide wafers were evaluated for defects using a KLA-Tencor® Surfscan® SP3 defect and surface quality inspection system, excluding a 2 mm wafer edge and using a 70 nm cutoff. Dishing was evaluated using an atomic force microscope (AFM) at 50×50 μmL / S (50% density). Table 7 lists the removal rate, dishing, and number of defects.

Table 13

[0096] As is readily apparent from the data shown in Table 7, pad 5C, which contains CHDM, demonstrated significantly improved planarity and a substantially improved defect rate (fewer defects), as evidenced by a reduction in dishing, while achieving a similar removal rate.

[0097] Example 8 Pads 5A, 5B, and 5C (from Example 5) were evaluated in tungsten CMP experiments. The pads were evaluated by polishing a Silyb 854 2k tungsten wafer using a Mirra® CMP tool (available from Applied Materials) and a W8900 tungsten CMP slurry available from Cabot Microelectronics Corporation. The slurry was diluted with 5 parts deionized water and hydrogen peroxide to 1 part of the W8900 slurry. The concentration of hydrogen peroxide at the time of use was 2%. The wafer was polished to an endpoint +30% over-polish time at a downforce of 2.0 psi, a platen speed of 115 rpm, a head speed of 121 rpm, and a slurry flow rate of 90 ml / min. The Saesol® C1 conditioner was used for 12 seconds at a downforce of 6 pounds to condition the polishing pad in situ between each wafer. The tungsten pattern removal rate and step height (etching and dishing) were evaluated with 1×1 μm line features having a pattern density of 50%.

Table 14

[0098] Based on the results shown in Table 8, pad 5C containing CHDM shows improved tungsten polish rate and improved planarity (essentially zero step height).

[0099] Example 9 To further evaluate the effect of CHDM levels in the experimental pads, pads 5C, 5D, 5E, and 5F (from Example 5) were evaluated in a tungsten CMP experiment. Similar to Example 8, the pads were evaluated by polishing Silyb 854 2k tungsten wafers using a Mirra® CMP tool (available from Applied Materials) and a W8900 tungsten CMP slurry available from Cabot Microelectronics Corporation. The slurry was diluted with 5 parts deionized water and hydrogen peroxide to 1 part W8900 slurry. The concentration of hydrogen peroxide at the time of use was 2%. The wafers were polished at a downforce of 2.0 psi, a platen speed of 115 rpm, and a head speed of 121 rpm, with a slurry flow rate of 90 ml / min to an endpoint +30% overpolish time. The polishing pads were conditioned in situ between each wafer using a Saesol® C1 conditioner at a downforce of 6 pounds for 12 seconds.

[0100] The removal rate of the tungsten pattern and the step height (etching and dishing) were evaluated with 1×1 μm line features at 50% density and reported in Table 9. The hardener molar ratio refers to the molar ratio of polyamine (dimethylthiotoluenediamine) to CHDM in the blended hardener (hardener mixture).

Table 15

[0101] As is apparent from the data shown in Table 9, the pad with a hardener molar ratio of 5.7 to 1 exhibits significantly improved planarity, as evidenced by the lower step height compared to the pad with a hardener ratio of 2.3:1. No dependence of the W pattern removal rate on the hardener ratio was observed.

[0102] Example 10 Pads 5A, 5G, 5H, and 5I were evaluated in a 3D NAND staircase CMP experiment. The pads were evaluated by polishing a Silyb 3D NAND patterned wafer using a Mirra® CMP tool and slurry D7400 available from Cabot Microelectronics Corporation. The slurry was diluted with six parts deionized water to one part D7400 slurry. The wafer was polished for 30 seconds, 60 seconds, and 90 seconds at a downforce of 3.0 psi, a platen speed of 100 rpm, a head speed of 85 rpm, and a slurry flow rate of 150 ml / min. The polishing pads were conditioned in-situ using a Saesol® DS8051 conditioner at a downforce of 6 pounds. The wafer topography was evaluated with a 10×5 mm feature having a 2 mm trend width on both sides. Table 10 shows the relative trench loss (compared to pad 5A without a diol hardener) at step heights of 0 Å, 1000 Å, and 2000 Å.

Table 16

[0103] Figure 3 shows a plot of step height versus trench loss at the center and mid-die locations of pads 5A, 5G, and 5H. As is apparent from the data shown in Figure 3 and Table 10, the polishing pad 5H containing a CHDM hardener provided excellent planarization efficiency with respect to trench loss in the 3D NAND staircase experiment.

[0104] Example 11 Pads 5A, 5J, and 5K (from Example 5) were evaluated in tungsten CMP experiments. The pads were evaluated by polishing a 754 TEOS-W 5kA patterned wafer (available from Advanced Materials Technology, Inc.) using a Reflexion® CMP tool (available from Applied Materials) and a W8900 tungsten CMP slurry (available from Cabot Microelectronics Corporation). The slurry was diluted with 5 parts deionized water and hydrogen peroxide to 1 part of the W8900 slurry. The hydrogen peroxide concentration at the time of use was 2%. The wafer was polished at a downforce of 3.0 psi, a platen speed of 80 rpm, a head speed of 81 rpm, and a slurry flow rate of 100 ml / min to endpoint +15 seconds overpolish. The polishing pad was conditioned ex-situ between each wafer using a 3M A122 conditioner at a downforce of 8 pounds for 24 seconds.

[0105] The wafer was evaluated after 60 seconds of polishing time to obtain the tungsten pattern removal rate for the first pass. After completion of the experiment, the tungsten removal rate for the second pass was obtained. Blanket TiN wafers were also polished under the same conditions to obtain the blanket TiN removal rate. Oxide erosion and dishing were evaluated with 1×1 μm line features having a 50% pattern density. The tungsten pattern removal rates for the first and second passes, oxide erosion, dishing, oxide loss, and blanket TiN removal rate are shown in Table 11 below.

Table 17

[0106] Based on the results shown in Table 11, pad 5K containing CHDM exhibits a better tungsten removal rate for the first pass than pad 5A and a tungsten removal rate approximately equivalent to that of pad 5J, while providing a significant improvement in oxide erosion (a 35% reduction compared to pad 5J).

[0107] Example 12 Pads 5A, 5J, 5K, and 5L (from Example 5) were evaluated in a tungsten CMP experiment. The pads were evaluated by polishing a 754 TEOS-W 5kA patterned wafer (available from Advanced Materials Technology, Inc.) using a Reflexion® CMP tool (available from Applied Materials) and a W8902 tungsten CMP slurry (available from Cabot Microelectronics Corporation). The slurry was diluted with 5 parts deionized water and hydrogen peroxide to 1 part of the W8902 slurry. The concentration of hydrogen peroxide at the time of use was 5%. The wafer was polished at a downforce of 3.0 psi, a platen speed of 100 rpm, a head speed of 101 rpm, and a slurry flow rate of 250 ml / min to an endpoint +30% overpolish. A Shinhan A37 conditioner was used at a downforce of 4.5 pounds for 100% of the polish time to condition the polish pad in-situ.

[0108] The tungsten pattern removal rate, oxide erosion, and dishing were evaluated with 1×1 μm line features at 50% density and reported in Table 12. The field oxide removal rate is also reported in Table 12.

Table 18

[0109] As is evident from the data shown in Table 12, pads 5K and 5L have significantly improved W removal rates compared to pad 5A and approximately equivalent W removal rates compared to pad 5J. Pads 5K and 5L (containing the CHDM hardener) also show a significant improvement in oxide erosion (a reduction of over 70%).

[0110] It will be appreciated that the polishing pad of the present invention may optionally have a polishing surface that includes grooves, channels, and / or perforations that facilitate the lateral transport of a polishing composition, such as slurry, across the polishing surface of the pad. Such grooves, channels, or perforations can be in substantially any suitable pattern, including, for example, inclined grooves, radial grooves, concentric grooves, helical or circular grooves, and / or XY cross-hatch grooves, and can be continuous or discontinuous in connectivity. Such optional grooves, channels, and / or perforations can further have substantially any suitable depth, width, and pitch. Additionally, the polishing pad can have two or more different groove patterns, as disclosed, for example, in U.S. Patent No. 9,180,570.

[0111] The polishing pad of the present invention is particularly suitable for use in conjunction with a chemical mechanical polishing (CMP) apparatus. Typically, the apparatus includes a platen that moves during use and has a velocity resulting from circular, linear, or circular motion. The disclosed polishing pads can be configured to adhere to the platen such that they move with the platen. The apparatus generally further includes a carrier that holds a workpiece, such as a wafer, that is polished by contacting the surface of the polishing pad and moving relative thereto. Polishing of the workpiece is typically performed by interposing a polishing composition and disposing the workpiece in contact with the polishing pad and generating relative motion between the polishing pad and the workpiece, whereby at least a portion of the workpiece is abraded and thereby the workpiece is polished. The polishing composition can include a liquid carrier (e.g., an aqueous carrier) and an optional abrasive. Depending on the type of workpiece being polished, the polishing composition can optionally further include one or more oxidizing agents, organic acids, complexing agents, pH buffers, surfactants, corrosion inhibitors, defoamers, biocides, and the like. The CMP apparatus can be any suitable CMP apparatus, many of which are known in the art.

[0112] General CMP apparatuses include in-situ polish endpoint detection systems, many of which are known in the art. Techniques for inspecting and monitoring the polishing process by analyzing light or other radiation reflected from the surface of a workpiece are known in the art and are commonly used in commercial CMP operations. Exemplary methods and systems are disclosed in U.S. Patent Nos. 5,196,353; 5,433,651; 5,609,511; 5,643,046; 5,658,183; 5,730,642; 5,838,447; 5,872,633; 5,893,796; 5,949,927; and 5,964,643. Accordingly, the polishing pad of the present invention may optionally include one or more transparent windows or openings formed therein to facilitate such endpoint detection.

[0113] The polishing pad of the present invention can be used alone or, optionally, as a polishing layer of a multi-layer laminated polishing pad. For example, the disclosed polishing pad can be used in combination with substantially any suitable sub-pad. Examples of sub-pads include polyurethane foam sub-pads (e.g., PORON® foam sub-pads from Rogers Corporation), impregnated felt sub-pads, microporous polyurethane sub-pads, or sintered urethane sub-pads. The sub-pad can be softer or harder than the disclosed polishing pad and, thus, can be more or less compressible and can have a Shore D hardness value lower or higher than that of the disclosed polishing pad. The sub-pad can optionally include grooves, channels, hollow sections, windows, openings, etc. When the disclosed pad is used with a sub-pad, an intermediate backing layer such as a polyethylene terephthalate film can be disposed between the polishing pad and the sub-pad. The disclosed embodiments are not limited to the use of a sub-pad or the characteristics of the sub-pad during use.

[0114] The disclosed polishing pads may be suitable for use in polishing many types of workpieces (e.g., substrates or wafers) and workpiece materials. For example, the disclosed pads may be used to polish workpieces including memory storage devices, semiconductor substrates, and glass substrates. Workpieces suitable for polishing with the polishing pads include memory or rigid disks, magnetic heads, MEMS devices, semiconductor wafers, field emission displays, and other microelectronic substrates, particularly microelectronic substrates including an insulating layer (e.g., silicon dioxide, silicon nitride, or a low dielectric material), and / or a metal-containing layer (e.g., copper, tantalum, tungsten, aluminum, nickel, titanium, platinum, ruthenium, rhodium, iridium or other noble metals). The disclosed embodiments are not limited with respect to the workpiece to be polished.

[0115] Although polishing pads using polyamine hardeners and CHDM hardeners and certain of their advantages are described in detail, it is to be understood that various changes, substitutions, and alternations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. A chemical mechanical polishing pad comprising a thermosetting polyurethane polishing layer, wherein the thermosetting polyurethane polishing layer comprises: an isocyanate-terminated urethane prepolymer; a polyamine curing agent; and a cyclohexanedimethanol curing agent; wherein the polyamine curing agent and the cyclohexanedimethanol curing agent are present in a molar ratio of polyamine curing agent to cyclohexanedimethanol curing agent in the range of 10:1 to 1:1, and the thermosetting polyurethane polishing layer has a Shore D hardness of greater than 60 to 85 at 25 °C. A chemical mechanical polishing pad.

2. The polishing pad according to claim 1, wherein the isocyanate-terminated urethane prepolymer is a reaction product of a toluene diisocyanate (TDI) compound or a methylene diphenyl diisocyanate (MDI) compound with a polytetramethylene ether glycol (PTMEG) or a polypropylene ether glycol.

3. The isocyanate-terminated urethane prepolymer is an aromatic prepolymer selected from the group consisting of a 75D prepolymer, an 80D prepolymer, and mixtures thereof, wherein the 75D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having a Shore D hardness of 75 when cured, and the 80D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having a Shore D hardness of 80 when cured. The polishing pad according to claim 1.

4. The polishing pad according to claim 1, wherein the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of an aniline diamine compound, a toluene diamine compound, an aminobenzoate compound, and mixtures thereof.

5. The polishing pad according to claim 4, wherein the aromatic diamine curing agent is selected from the group consisting of 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof.

6. The polishing pad according to claim 1, wherein the molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of 10:1 to 1.5:

1.

7. The polishing pad according to claim 1, wherein the thermosetting polyurethane polishing layer comprises surface irregularities, and the surface irregularities have a ratio of the storage modulus at 25 °C to the storage modulus at 75 °C in the range of 3 to 20.

8. The isocyanate-terminated urethane prepolymer includes a 75D prepolymer; The surface irregularities have a storage modulus (E') at 25°C exceeding 500 MPa, and the 75D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having a 75 Shore D hardness when cured. The polishing pad according to claim 7.

9. The surface irregularities have a tensile strength at 25°C exceeding 100 MPa. The polishing pad according to claim 8.

10. The isocyanate-terminated urethane prepolymer includes an 80D prepolymer; The surface irregularities have a storage modulus (E') at 25°C exceeding 1000 MPa and a Shore D hardness at 25°C exceeding 70, and the 80D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having an 80 Shore D hardness when cured. The polishing pad according to claim 7.

11. The surface irregularities have a tensile strength at 25°C exceeding 50 MPa. The polishing pad according to claim 10.

12. The thermosetting polyurethane polishing layer further includes a sufficient amount of hollow microspheres so that the thermosetting polyurethane polishing layer has a porosity in the range of 10 to 50 percent. The polishing pad according to claim 1.

13. The isocyanate-terminated urethane prepolymer is an aromatic prepolymer selected from the group consisting of a 75D prepolymer, an 80D prepolymer, and mixtures thereof; The polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof; The molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of 10:1 to 1.5:1, The 75D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having a 75 Shore D hardness when cured, and the 80D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having an 80 Shore D hardness when cured. The polishing pad according to claim 1.

14. The thermosetting polyurethane polishing layer is adhered to the sub-pad. The polishing pad according to claim 1.

15. A chemical mechanical polishing pad comprising a thermosetting polyurethane polishing layer, wherein the thermosetting polyurethane polishing layer is an isocyanate-terminated urethane prepolymer; a hardener mixture comprising a polyamine hardener and a cyclohexanedimethanol hardener, the hardener mixture comprising 5 to 50 mole percent of the cyclohexanedimethanol hardener; the thermosetting polyurethane polishing layer has a Shore D hardness of greater than 60 to 85 at 25° C., a chemical mechanical polishing pad.

16. The polishing pad according to claim 15, wherein the isocyanate-terminated urethane prepolymer is a reaction product of a toluene diisocyanate (TDI) compound or a methylene diphenyl diisocyanate (MDI) compound and polytetramethylene ether glycol (PTMEG) or polypropylene ether glycol.

17. The isocyanate-terminated urethane prepolymer is an aromatic prepolymer selected from the group consisting of a 75D prepolymer, an 80D prepolymer, and mixtures thereof, the 75D prepolymer being a prepolymer that produces the thermosetting polyurethane polishing layer having a Shore D hardness of 75 when cured, and the 80D prepolymer being a prepolymer that produces the thermosetting polyurethane polishing layer having a Shore D hardness of 80 when cured. The polishing pad according to claim 15.

18. The polishing pad according to claim 15, wherein the polyamine hardener is an aromatic diamine hardener selected from the group consisting of aniline diamine compounds, toluene diamine compounds, aminobenzoate compounds, and mixtures thereof.

19. The polishing pad according to claim 18, wherein the aromatic diamine hardener is selected from the group consisting of 4,4-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof.

20. The polishing pad according to claim 15, wherein the hardener mixture comprises 10 to 40 weight percent of the cyclohexanedimethanol hardener.

21. The polishing pad according to claim 15, wherein the hardener mixture consists of the polyamine hardener and the cyclohexanedimethanol hardener.

22. The polishing pad according to claim 15, wherein the thermosetting polyurethane polishing layer includes surface irregularities, and the surface irregularities have a ratio of the storage modulus at 25° C. to the storage modulus at 75° C. within the range of 3 to 20.

23. The isocyanate-terminated urethane prepolymer includes a 75D prepolymer; The surface irregularities have a storage modulus (E') at 25 °C exceeding 500 MPa, and the 75D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having a 75 Shore D hardness when cured. The polishing pad according to claim 22.

24. The polishing pad according to claim 23, wherein the surface irregularities have a tensile strength at 25 °C exceeding 100 MPa.

25. The isocyanate-terminated urethane prepolymer includes an 80D prepolymer; The surface irregularities have a storage modulus (E') at 25 °C exceeding 1000 MPa and a Shore D hardness at 25 °C exceeding 70, and the 80D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having an 80 Shore D hardness when cured. The polishing pad according to claim 22.

26. The polishing pad according to claim 25, wherein the surface irregularities have a tensile strength at 25 °C exceeding 50 MPa.

27. The polishing pad according to claim 15, wherein the thermosetting polyurethane polishing layer further includes a sufficient amount of hollow microspheres so that the thermosetting polyurethane polishing layer has a porosity in the range of 10 to 50 percent.

28. The isocyanate-terminated urethane prepolymer is an aromatic prepolymer selected from the group consisting of a 75D prepolymer, an 80D prepolymer, and mixtures thereof; The polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof; The curing agent mixture includes 10 to 40 weight percent of the cyclohexanedimethanol curing agent, The 75D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having a 75 Shore D hardness when cured, and the 80D prepolymer is a prepolymer that produces the thermosetting polyurethane polishing layer having an 80 Shore D hardness when cured. The polishing pad according to claim 15.

29. The polishing pad according to claim 15, wherein the thermosetting polyurethane polishing layer is adhered to a sub-pad.

30. A method for manufacturing a thermosetting polishing pad, (a)(i) An isocyanate-terminated urethane prepolymer, (ii) a polyamine curing agent; and (iii) a cyclohexanedimethanol curing agent are mixed to obtain a mixture, wherein the diamine curing agent and the cyclohexanedimethanol curing agent are present in a molar ratio of diamine curing agent to cyclohexanedimethanol curing agent in the range of 10:1 to 1:1, obtaining a mixture; (b) Heating the mixture in a mold to obtain a pre-cured pad; (c) Curing the pre-cured pad to obtain a polishing pad, The thermosetting polishing pad has a Shore D hardness of more than 60 to 85 at 25 °C, Method.

31. (d) The method according to claim 30, further comprising machining the polishing pad to remove the formed skin to obtain a polishing pad having a desired thickness.

32. (e) The method according to claim 31, further comprising adhering the polishing pad to a sub-pad to obtain a multi-layer polishing pad.

33. The isocyanate-terminated urethane prepolymer is an aromatic prepolymer selected from the group consisting of 75D prepolymer, 80D prepolymer, and mixtures thereof; The polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof; The molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of 10:1 to 1.5:1, The 75D prepolymer is a prepolymer that produces a thermosetting polyurethane polishing layer having a Shore D hardness of 75 when cured, and the 80D prepolymer is a prepolymer that produces a thermosetting polyurethane polishing layer having a Shore D hardness of 80 when cured. The method according to claim 30.

34. A method for chemically mechanical polishing of a semiconductor substrate, comprising: (a) contacting the substrate with a polishing pad and a polishing composition, The polishing pad is (i) an isocyanate-terminated urethane prepolymer, (ii) a polyamine curing agent, and (iii) having a thermosetting polishing layer containing a cyclohexanedimethanol curing agent, The polyamine curing agent and the cyclohexanedimethanol curing agent are present in a molar ratio of polyamine curing agent to cyclohexanedimethanol curing agent in the range of 10:1 to 1:1, contacting; (b) relatively moving the polishing pad with respect to the substrate; (c) polishing the substrate to remove a part of a layer from the substrate, thereby polishing the substrate, (2) the polishing pad has a Shore D hardness of more than 60 to 85 at 25°C; (3) a method. (4)

35. (5) the isocyanate-terminated urethane prepolymer is an aromatic prepolymer selected from the group consisting of a 75D prepolymer, an 80D prepolymer, and mixtures thereof; (6) the polyamine curing agent is an aromatic diamine curing agent selected from the group consisting of 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, and mixtures thereof; (7) the molar ratio of the polyamine curing agent to the cyclohexanedimethanol curing agent is in the range of 10:1 to 1.5:1; (8) the 75D prepolymer is a prepolymer that produces a thermosetting polyurethane polishing layer having a Shore D hardness of 75 when cured, and the 80D prepolymer is a prepolymer that produces a thermosetting polyurethane polishing layer having a Shore D hardness of 80 when cured; (9) The method according to claim 34.

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