Dual additive polishing composition for glass substrates

Abstract

The present invention relates to a chemical mechanical polishing composition comprising, consisting of, or consisting essentially of: a liquid vehicle, abrasive particles in the liquid vehicle, a pyrophosphate compound, and a sulfonate compound or a compound comprising a quaternary ammonium group.

Description

Technical Field

[0001] The disclosed embodiments relate to chemical mechanical polishing compositions for polishing glass substrates, and more particularly, to compositions including a pyrophosphate compound and a sulfonate compound or a quaternary amine. Background Art

[0002] There is a continuing demand for increased storage capacity and miniaturization in the hard disk drive industry. This has led to a corresponding need for smaller memory or hard disks with increased storage (or data) density and a need for improved methods for polishing such memory or hard disks.

[0003] As used herein, the term "memory or hard disk" refers to any magnetic disk, hard disk, hard disk, or memory disk used to retain information in electromagnetic form. These memory or hard disks are referred to herein simply as disks or substrates, and are typically one of two types: (i) nickel-phosphorus plated aluminum disks, or (ii) glass disks. During manufacturing, the disks are polished to tight surface precision tolerances before the magnetic material that is ultimately used for data storage is deposited.

[0004] It is well known that the data storage industry faces constant and sometimes extreme downward price pressure. In order to maintain an economically favorable process, high throughput is usually required, and therefore high material removal rates are required during polishing operations. However, increasing the removal rate leads to increased surface roughness or surface waviness.

[0005] Although chemical mechanical polishing (CMP) compositions and methods are commercially available for polishing nickel phosphorus and / or glass magnetic disks, there is an unmet need for improved polishing compositions that can improve throughput and achieve increased storage density. Specifically, there is an unmet need for polishing compositions that achieve improved surface accuracy (e.g., reduced surface roughness and surface waviness) and high material removal rates. Summary of the invention

[0006] A chemical mechanical polishing composition is disclosed, which comprises, consists of, or consists essentially of a liquid carrier, abrasive particles in the liquid carrier, a pyrophosphate compound, and a sulfonate compound including a sulfonate anionic surfactant or a polysulfonic acid.

[0007] In another embodiment, a polishing composition is disclosed that comprises, consists of, or consists essentially of: a liquid carrier; abrasive particles in the liquid carrier; a pyrophosphate compound; and a cationic compound comprising a quaternary ammonium cation. DETAILED DESCRIPTION

[0008] A chemical mechanical polishing composition is disclosed. The composition comprises, consists of, or consists essentially of a liquid carrier, abrasive particles in the liquid carrier, a pyrophosphate compound, and a sulfonate anionic surfactant or an anionic polymer including a sulfonic acid group or a compound including a quaternary ammonium group. In a specific embodiment, the composition comprises, consists of, or consists essentially of a liquid carrier, abrasive particles in the liquid carrier, and a synergistic combination of a pyrophosphate compound and a sulfonate anionic surfactant or an anionic polymer including a sulfonic acid group, or a synergistic combination of a pyrophosphate compound and a compound including a quaternary ammonium group.

[0009] The disclosed compositions can be advantageously used for polishing glass substrates, such as glass substrates used to construct memory or hard disks in hard disk drives, but the disclosed embodiments are not limited in this regard. As described in more detail below as an example, the disclosed polishing compositions include synergistic combinations of chemical additives and have been found to advantageously provide significantly improved polishing rates. It has also been found that certain disclosed embodiments can provide similar or even improved surface accuracy (e.g., surface waviness).

[0010] It should be understood that the term "synergy" (or synergy) is used according to the standard dictionary definition of the term. Synergy is defined as the interaction of elements such that their combined effect is greater than the sum of their individual effects (Dictionary of Science and Technology, Academic Press, 1992). In the disclosed embodiments, it has been found that the combination of a pyrophosphate compound and a sulfonate compound (e.g., a disulfonate anionic surfactant) or a quaternary ammonium compound increases the removal rate of glass substrate polishing to an extent that exceeds the sum of the individual contributions of the pyrophosphate compound and the sulfonate compound. In addition, as described in more detail in the examples below, it was unexpectedly found that adding a sulfonate compound or a quaternary ammonium compound to a composition including a pyrophosphate compound increases the removal rate (as opposed to the expected decrease in removal rate).

[0011] The disclosed polishing composition generally contains abrasive particles dispersed or suspended in a liquid carrier. The liquid carrier is used to facilitate application of the abrasive particles and chemical additives to the surface of the substrate to be polished. The liquid carrier may include any suitable carrier (e.g., solvent), including lower alcohols (e.g., methanol, ethanol, etc.), ethers (e.g., dioxane, tetrahydrofuran, etc.), water, and mixtures thereof. The liquid carrier preferably consists of or consists essentially of deionized water.

[0012] The disclosed polishing composition includes abrasive particles in a liquid carrier, such as dispersed or suspended in a liquid carrier. The abrasive particles may include substantially any abrasive particles suitable for polishing a glass substrate, such as metal oxide particles, diamond particles, and / or ceramic particles. For example, the metal oxide particles may include silicon dioxide, ceria, and / or aluminum oxide abrasive particles, including colloidal and / or fumed metal oxide particles. The ceramic particles may include materials such as cubic boron nitride or silicon carbide.

[0013] Preferred embodiments include silica grinding particles, such as fumed or colloidal silica grinding particles. As used herein, the term colloidal silica particles refers to silica particles prepared by a wet process. Colloidal silica can be a precipitated or condensation-polymerized silica, which can be prepared using any method known to those of ordinary skill in the art, such as by a sol-gel process or by silicate ion exchange. Condensation-polymerized silica particles are typically prepared by condensing Si(OH)4 to form generally spherical particles. Fumed silica is obtained by pyrolysis or flame hydrolysis of reacting silicon tetrachloride with oxygen in a flame, and typically has an aggregate structure in which generally spherical primary particles are melted together to form chain-like aggregates.

[0014] The abrasive particles (e.g., colloidal silica particles) can have substantially any suitable particle size. In the industry, various means can be used to define the particle size of particles suspended in a liquid carrier. For example, the particle size can be defined as the diameter of the smallest sphere containing the particle, and can be measured using a variety of commercially available instruments, such as a CPS disc centrifuge model DC24000HR (available from CPS Instruments, Prairieville, Louisiana) or a Malvern Instruments, Inc. )of The abrasive particles may have an average particle size of about 5 nm or more (e.g., about 10 nm or more, about 15 nm or more, or about 20 nm or more). The abrasive particles may have an average particle size of about 100 nm or less (e.g., about 50 nm or less, about 45 nm or less, or about 40 nm or less). Thus, the colloidal silica particles may have an average particle size in the range of about 5 nm to about 50 nm (e.g., about 10 nm to about 40 nm, about 15 nm to about 40 nm, or about 20 nm to about 40 nm). For example, in one advantageous embodiment, the abrasive particles comprise colloidal silica having an average particle size of about 30 nm.

[0015] The polishing composition may include substantially any suitable amount of the above-mentioned abrasive particles. For example, the polishing composition may include about 1 wt % or more of abrasive particles (e.g., about 2 wt % or more, about 3 wt % or more, or about 5 wt % or more) at the point of use. The amount of abrasive particles in the polishing composition may include about 20 wt % or less (e.g., about 15 wt % or less, about 12 wt % or less, or about 10 wt % or less) at the point of use. Thus, it should be understood that the amount of abrasive particles may be within the range bounded by any two of the above endpoints, for example, in the range of about 1 wt % to about 20 wt % at the point of use (e.g., about 2 wt % to about 20 wt %, about 5 wt % to about 15 wt %, about 5 wt % to about 12 wt %, or about 5 wt % to about 10 wt %). For example, in one advantageous embodiment, the polishing composition may include about 8.5 wt % colloidal silica at the point of use.

[0016] The disclosed polishing composition further comprises a pyrophosphate compound. As used herein, the term pyrophosphate compound refers to a compound comprising a phosphorus oxyanion containing two phosphorus atoms in a POP linkage. It should be understood that pyrophosphate compounds are commonly referred to as diphosphates or diphosphate compounds in the chemical arts (perhaps because the phosphorus oxyanion comprises two phosphorus atoms). The disclosed embodiments may include substantially any suitable pyrophosphate compound, including, for example, disodium pyrophosphate (DSPP), tetrasodium pyrophosphate (TSPP), dipotassium pyrophosphate (DKPP), and tetrapotassium pyrophosphate (TKPP). Preferred pyrophosphate compounds include TSPP and TKPP.

[0017] The polishing composition may include substantially any suitable amount of the above-mentioned pyrophosphate compound. For example, the polishing composition may include about 0.001 wt.% (10 ppm by weight) or more of the pyrophosphate compound (e.g., about 0.01 wt.% or more, or about 0.02 wt.% or more) at the point of use. The amount of the pyrophosphate compound in the polishing composition may be about 1 wt.% or less (e.g., about 0.5 wt.% or less, about 0.3 wt.% or less, or about 0.2 wt.% or less) at the point of use. Thus, it should be understood that the amount of the pyrophosphate compound may be within the range bounded by any two of the above endpoints, for example, in the range of about 0.001 wt.% to about 1 wt.% at the point of use (e.g., about 0.01 wt.% to about 0.5 wt.%, about 0.01 wt.% to about 0.3 wt.%, about 0.02 wt.% to about 0.3 wt.%, or about 0.02 wt.% to about 0.2 wt.%). For example, in certain advantageous embodiments, the polishing composition can comprise about 0.03 wt.%, 0.06 wt.%, 0.08 wt.%, or about 0.12 wt.% TKPP at the point of use.

[0018] The disclosed polishing composition further includes a second additive compound (in addition to the pyrophosphate compound). The second additive compound may include any of the following: (i) a sulfonate compound including a sulfonate anionic surfactant or an anionic polymer including a sulfonic acid group, or (ii) a compound including a quaternary ammonium group (also referred to herein as a quaternary amine or quaternary ammonium compound). As described in more detail in the following examples, the combination of the pyrophosphate compound and the second additive compound can be a synergistic combination that advantageously provides a significantly increased removal rate during polishing and can also improve the surface accuracy of the polished substrate.

[0019] In certain embodiments, the second additive compound may include substantially any suitable sulfonate anionic surfactant or anionic polymer (polysulfonic acid) including a sulfonic acid group. For example, subclasses of suitable sulfonate anionic surfactants may include alkylaryl sulfonates (e.g., alkylbenzene sulfonates, such as dodecylbenzene sulfonate), alkyl sulfonates (e.g., olefin sulfonates, such as α-olefin sulfonates, alkyl glyceride sulfonates, alkyl ether sulfonates, and alkyl sulfoacetates), oxyalkyl diphenyl sulfonates, sulfosuccinates (e.g., monoalkyl sulfosuccinates and dialkyl sulfosuccinates), acyl taurates, and acyl isethionates.

[0020] In certain preferred embodiments, the sulfonate anionic surfactant comprises a disulfonate anionic surfactant, such as an oxyalkyl diphenyl disulfonate anionic surfactant having the following structure:

[0021]

[0022] Where R is C1-C 30 , preferably C6-C 30 , more preferably C6-C 22 A linear or branched, saturated or unsaturated alkyl group, wherein the alkyl group optionally contains one or more heteroatoms selected from the group consisting of O and N, and wherein X + is H or a cation such as an alkali metal cation or an alkaline earth metal cation (e.g., sodium, potassium, lithium, calcium, magnesium, etc.). Examples of suitable oxyalkyl diphenyl disulfonate surfactants include those available under the trade name 2A1, 3B2, 8390, C6L, C10L and 30599 is a surfactant commercially available from Dow Chemical Company (Midland, Mich.).

[0023] Non-limiting examples of polymers or copolymers containing sulfonic acid groups include polystyrene sulfonic acid, polyvinyl sulfonic acid (PVSA), poly(2-acrylamido-2-methylpropane sulfonic acid), poly(styrene sulfonic acid-co-maleic acid), and poly(acrylic acid)-co-poly(2-acrylamido-2-methylpropane sulfonic acid).

[0024] In embodiments including a sulfonate anionic surfactant or a polysulfonic acid, the composition may include substantially any suitable amount of the above-described second additive compound. For example, the polishing composition may include about 0.001 wt. % (10 ppm by weight) or more of the second additive compound (e.g., about 0.01 wt. % or more, or about 0.02 wt. % or more) at the point of use. The amount of the second additive compound in the polishing composition may be about 1 wt. % or less (e.g., about 0.5 wt. % or less, about 0.3 wt. % or less, or about 0.2 wt. % or less) at the point of use. Thus, it should be understood that the amount of the second additive compound may be within the range defined by any two of the above endpoints, for example, within the range of about 0.001 wt. % to about 1 wt. % at the point of use (e.g., about 0.01 wt. % to about 0.5 wt. %, about 0.01 wt. % to about 0.3 wt. %, about 0.02 wt. % to about 0.3 wt. %, or about 0.02 wt. % to about 0.2 wt. %). For example, in certain advantageous embodiments, the polishing composition may include about 0.05 wt. % at the point of use. 2A1, 3B2, C6L or C10L.

[0025] The disclosed embodiments including sulfonate anionic surfactants or polysulfonic acids may further optionally include an anionic (or another anionic) polymer, such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(maleic acid) (PMA), etc. The use of such polymers in polishing compositions can advantageously control friction during polishing operations and can reduce substrate waviness. Such polymers do not interact synergistically with pyrophosphate and / or sulfonate compounds. Example compositions may include from about 0 to about 1000 ppm by weight of such optional anionic polymers (e.g., from about 30 to about 300 ppm by weight of PAA or PMAA in certain embodiments).

[0026] It should be understood that the term "sulfonate" as used herein refers to the ionized (anionic) form of the surfactant (or polymer), which includes at least one anionic oxygen, and the acid form of the surfactant, which includes at least one acidic OH group. As is well known in the chemical arts, the acid forms of many sulfur-based surfactants are generally highly acidic and tend to ionize even at relatively low pH values ​​(e.g., pH 2 to 3). Therefore, the anionic surfactants in the CMP compositions of the present invention will generally be present primarily in the anionic form, regardless of whether the surfactant is added to the composition in salt form or acid form.

[0027] In certain other embodiments, the second additive compound may include substantially any suitable quaternary amine (ie, substantially any suitable compound including a quaternary ammonium group). Such a compound may be represented by the following chemical formula: + R'R"R"', wherein R', R" and R"' may be the same or different and may include substantially any carbon-containing compound. It should be understood that the nitrogen onium group in the quaternary ammonium may have a structure corresponding to the structure of the tertiary amine used as the starting material. For example, if the tertiary amine is triethylamine, the corresponding quaternary ammonium group is triethylammonium. The quaternary ammonium group may, for example, be a quaternary ammonium group having a saturated hydrocarbon group (such as trimethylamine, triethylamine, dimethylethylamine, etc.), a hydroxyl group, an ether group, an amino group, and / or a quaternary ammonium group having a hydrocarbon group containing an unsaturated carbon bond (such as dimethylethanolamine, dimethylaniline, diethylaniline, dimethylbenzylamine, pyridine, etc.).

[0028] In a preferred embodiment, the compound comprising a quaternary ammonium group comprises a tetramethylammonium group, a tetraethylammonium group, a tetrabutylammonium group, a benzyltributylammonium group or a mixture thereof. In a most preferred embodiment, the compound comprises tetraethylammonium hydroxide.

[0029] In embodiments including a compound having a quaternary ammonium group, the composition can include substantially any suitable amount of the compound. For example, the polishing composition can include about 0.001 wt % (10 ppm by weight) or more of the compound at the point of use (e.g., about 0.01 wt % or more, or about 0.02 wt % or more). At the point of use, the amount of the compound in the polishing composition can be about 0.5 wt % or less (e.g., about 0.4 wt % or less, about 0.3 wt % or less, or about 0.2 wt % or less). Thus, it should be understood that the amount of the compound can be within the range bounded by any two of the above endpoints, for example, in the range of about 0.001 wt % to about 0.5 wt % at the point of use (e.g., about 0.01 wt % to about 0.5 wt %, about 0.01 wt % to about 0.4 wt %, about 0.02 wt % to about 0.3 wt %, or about 0.02 wt % to about 0.2 wt %). For example, in certain advantageous embodiments, the polishing composition can comprise approximately 0.02 wt.%, 0.05 wt.%, 0.1 wt.%, or 0.2 wt.% tetraethylammonium hydroxide at the point of use.

[0030] The disclosed polishing composition is generally acidic, having a pH value of less than about 7. For example, the pH value may be greater than about 1 (e.g., greater than about 1.5). The pH value may be less than about 5 (e.g., less than about 4, less than about 3.5, or less than about 3). Therefore, it should be understood that the pH value of the polishing composition can be defined by any of the aforementioned endpoints, for example, in the range of about 1 to about 5 (e.g., about 1 to about 4, about 1.5 to about 3.5, or about 1.5 to about 3). For polishing compositions including pyrophosphate compounds and sulfonate compounds, the pH value may most preferably be in the range of about 1.5 to about 2. For polishing compositions including pyrophosphate compounds and quaternary amines, the pH value may most preferably be in the range of about 2 to about 3.

[0031] The pH of the polishing composition can be achieved and / or maintained by any suitable method. The polishing composition can include substantially any suitable pH adjuster or buffer system known to those skilled in the art of chemistry. For example, suitable pH adjusters can include various acids, including nitric acid, sulfuric acid, phosphoric acid, and the like.

[0032] The disclosed polishing compositions may include substantially any additional optional chemical additives. For example, the disclosed compositions may further include one or more dispersants and / or biocides. Such additional additives are entirely optional. The disclosed embodiments are not limited thereto and do not require the use of any one or more of such additives. In embodiments that further include a biocide, the biocide may include any suitable biocide.

[0033] The polishing composition can be prepared using any suitable technique, many of which are known to those skilled in the art. The polishing composition can be prepared in a batch or continuous process. In general, the polishing composition can be prepared by combining its components in any order. The term "component" as used herein includes individual ingredients (e.g., colloidal silica, pyrophosphate, and a second additive compound).

[0034] For example, the polishing composition components can be added directly to a dispersion including abrasive particles. Alternatively, the abrasive can be added to a solution including the pyrophosphate and the second additive compound. In either manner, any suitable technique can be used to blend the abrasive particles and other components together to achieve adequate mixing. Such blending / mixing techniques are well known to those of ordinary skill in the art.

[0035] The polishing composition of the present invention may also be provided as a concentrate intended to be diluted with an appropriate amount of water prior to use. In such embodiments, the polishing composition concentrate may include an abrasive (e.g., silica), a pyrophosphate compound, a second additive compound, and any other optional compounds in amounts such that upon dilution of the concentrate with an appropriate amount of water, each component in the polishing composition will be present in the polishing composition in an amount within the appropriate ranges described above for each component. For example, colloidal silica and other optional components may each be present in the polishing composition in an amount of about 2 times (e.g., about 3 times, about 4 times, or about 5 times) greater than the point-of-use concentration described above for each component, such that upon dilution of the concentrate with an equal volume (e.g., 1 equal volume of water, 2 equal volumes of water, 3 equal volumes of water, or 4 equal volumes of water), each component will be present in the polishing composition in an amount within the ranges described above for each component. In addition, as will be appreciated by one of ordinary skill in the art, the concentrate may contain an appropriate portion of the water present in the final polishing composition to ensure that the other components are at least partially or completely dissolved in the concentrate.

[0036] The disclosed polishing composition can be advantageously used for polishing glass substrates, and preferably for polishing hard disk glass substrates. The disclosed composition can be used in combination with a polishing machine suitable for polishing glass substrates, such as hard disk glass substrates. Such polishing machines typically include an upper platen and a lower platen and are configured to polish both sides of multiple substrates simultaneously. A polishing pad is mounted on each platen and the platens typically rotate independently in opposite directions.

[0037] During the polishing operation, the substrate is loaded on one or more carriers that mesh with the internal and external gears on the lower platen. The rotation rate of the carrier is controlled by controlling the rotation of the gears. The upper platen is lowered into contact with the substrate, and the polishing composition is dispensed to the substrate via the upper platen (and upper pad). The platen and carrier rotation rates are selected so that the upper and lower sides of the substrate are polished at approximately the same rate.

[0038] The effectiveness of the polishing process can be characterized in a variety of ways, for example, based on the polishing removal rate and the surface roughness or surface waviness of the polished substrate. The removal rate can be determined, for example, by measuring the weight loss (by weighing the substrate before and after polishing) to determine the amount of substrate removed per unit polishing time. Surface roughness can be evaluated based on average roughness (Ra) or surface waviness (HMS_Wq), and can be measured, for example, via a profilometer or atomic force microscopy (AFM) or using a Candela 6100 or 6300 device such as that available from KLA Tencor. Determined via optical measurement techniques.

[0039] Any suitable polishing pad can be used to polish a substrate with the disclosed composition. Suitable pads include, for example, woven and non-woven polishing pads. In addition, suitable polishing pads can include any suitable polymer having different densities, hardnesses, thicknesses, compressibility, ability to rebound after compression, and compression modulus. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbons, polycarbonates, polyesters, polyacrylates, polyethers, polyethylene, polyamides, polyurethanes, polystyrenes, polypropylenes, coformed products thereof, and mixtures thereof.

[0040] It should be understood that the present disclosure includes many embodiments, including (but not limited to) the embodiments listed in the claims.

[0041] The following examples further illustrate the invention but, of course, should not be construed as limiting its scope in any way.

[0042] Example 1

[0043] This example illustrates the synergistic combination of a pyrophosphate compound and a sulfonate anionic surfactant in the disclosed polishing compositions. Each polishing composition includes 8.5 weight percent of colloidal silica having an average particle size of 30 nm and nitric acid sufficient to adjust the pH to 1.8. Polishing composition 1A includes no other components. Polishing compositions 1B to 1I further include tetrapotassium pyrophosphate (TKPP) and / or an oxyalkyl diphenyl disulfonate anionic surfactant ( C10L) (all amounts are in weight percent).

[0044] A Hamai 9B double-sided polishing tool was used with a lower plate speed of 60 rpm, a carrier rotation rate of 20 rpm, a carrier rotation number of 12 rpm, and a g / cm 2Six separate glass disks (substrates) were polished for 11 minutes using each composition (six disks polished simultaneously per pass) at a down force of 1000 g and a slurry flow rate of 600 ml / min. The polishing rate was determined based on mass loss and the surface waviness (HMS_Wq) of two of the six disks was determined using a Candela 6100 measurement tool. The results for removal rate and surface waviness are reported in Table 1. The results were normalized to the removal rate and surface waviness achieved using Polishing Composition 1A.

[0045] Table 1

[0046]

[0047]

[0048] As described in Table 1, the addition of disulfonate surfactants (1B and 1C) to the base composition (1A) improved the surface waviness at the expense of a reduction in removal rate (waviness decreased to normalized values ​​of 76 and 66 at the expense of a reduction in removal rate to normalized values ​​of 85 and 73). The addition of pyrophosphates (1D, 1E, 1F, 1G, and 1H) to the base composition (1A) was observed to increase the removal rate at the expense of increased surface waviness (removal rate increased with increasing TKPP concentration to normalized values ​​of 115, 130, 138, 152, and 151 at the expense of an increase in waviness to normalized values ​​of 110, 115, 115, 120, and 121).

[0049] An unexpected synergistic interaction was observed for composition 1H, where the addition of a disulfonate surfactant to a composition including a pyrophosphate compound significantly improved both the removal rate and the surface waviness. Comparing the results for composition II with composition IF, the addition of a disulfonate surfactant increased the removal rate from a normalized value of 138 to 155, and decreased the waviness from a normalized value of 115 to 107. The further improvement in removal rate was unexpected (since the addition of a disulfonate surfactant was observed to decrease the removal rate in compositions IB and 1C) and synergistic. If the combination of pyrophosphate and disulfonate anionic surfactants were only additive (or less), the maximum removal rate for composition II would be expected to be 111 (an increase of 38 plus a decrease of 27 gives a net increase of 11). Therefore, the observed removal rate of 155 is clear evidence of synergy.

[0050] Example 2

[0051] This example further illustrates the effect of the synergistic combination of the pyrophosphate compound and the anionic sulfonate surfactant in the disclosed polishing composition and the optional anionic polymer additive. Each polishing composition includes 8.5 weight percent of colloidal silica having an average particle size of 30 nm and nitric acid sufficient to adjust the pH to 1.8. Polishing Composition 1C, Polishing Composition 1G, and Polishing Composition 1I are described in Example 1 above. Polishing Compositions 2A to 2G further include TKPP and / or C10L (all amounts are weight percent). Compositions 2A to 2G further included 0.01 weight percent (100 ppm by weight) of polyacrylic acid having a molecular weight of 250,000 g / mol.

[0052] Six separate glass disks (substrates) were polished using each composition using a Binjing 9B double-sided polishing tool with the polishing conditions in Example 1 above. The polishing rate and surface waviness HMS_Wq were also determined as described above for Example 1. The results for removal rate and surface waviness are reported in Table 2. The results were normalized to the removal rate and surface waviness achieved using Polishing Composition 1A reported in Table 1.

[0053] Table 2

[0054]

[0055]

[0056] As shown in Table 2, the addition of PAA was observed to reduce surface waviness and removal rate. In the absence of TKPP, the addition of PAA to the composition including the disulfonate surfactant (compare Composition 2A with Composition 1C) reduced the removal rate from a normalized value of 73 to 72 and reduced the waviness from a normalized value of 66 to 60. PAA did not participate in or interfere with the synergistic effect between the pyrophosphate compound and the disulfonate surfactant. In the composition including the synergistic combination of TKPP and the disulfonate surfactant, the addition of PAA (compare Composition 2B with Composition II) reduced the removal rate from a normalized value of 155 to 154 and reduced the waviness from a normalized value of 107 to 102.

[0057] A synergistic interaction between the pyrophosphate compound and the disulfonate surfactant was also observed in compositions 2C to 2G, where the addition of the disulfonate surfactant to the composition including TKPP significantly improved both the removal rate and the surface waviness. Comparing compositions 2C-2F to composition 1G, the removal rate was observed to increase from a normalized value of 152 to normalized values ​​of 156, 163, 174, and 185 as the concentration of the disulfonate surfactant increased, and the waviness was observed to decrease from a normalized value of 120 to normalized values ​​of 117, 109, 106, and 102.

[0058] Example 3

[0059] This example shows that the above synergistic interaction is not observed in polishing compositions including other phosphate compounds (in other words, the synergistic interaction is only observed in compositions including pyrophosphate compounds). As described in Example 1 above, each polishing composition includes 8.5 weight percent of colloidal silica having an average particle size of 30 nm and nitric acid sufficient to adjust the pH to 1.8. Polishing Composition 1G and Polishing Composition 2E are described in Examples 1 and 2 above. Polishing Composition 3A and Polishing Composition 3B further include 0.093 weight percent of hydroxyethylidene diphosphonic acid (HEDP), Composition 3C and Composition 3D further include 0.259 weight percent of diethylenetriamine pentanyl (methylenephosphonic acid) (DTPMPA), Composition 3E and Composition 3F further include 0.122 weight percent of 2-phosphonobutane 1,2,4-tricarboxylic acid (PBTC), and Polishing Composition 3G and Polishing Composition 3H further include 0.5 weight percent of tartaric acid (carboxylic acid). It should be noted that composition 1G, composition 2E and compositions 3A-3H have the same molar concentration of phosphate or carboxylic acid additives. Composition 1G, composition 3B, composition 3D, composition 3F and composition 3H further include 0.05 weight percent of an oxidized alkyl diphenyl disulfonate surfactant ( C10L). The amounts of additives are listed in Table 3.

[0060] Six separate glass disks (substrates) were polished using each composition using a Binjing 9B double-sided polishing tool with the polishing conditions in Example 1 above. The polishing rate and surface waviness HMS_Wq were also determined as described above in Example 1. The results for removal rate and surface waviness are reported in Table 3. The results were normalized to the removal rate and surface waviness achieved using Polishing Composition 1A reported in Table 1.

[0061] Table 3

[0062]

[0063] As shown in Table 2, the synergistic effect observed in Examples 1 and 2 above was observed only in compositions including pyrophosphate compounds (compare Composition 1G with Composition 2E as described above in Example 2). No synergistic effect was observed in compositions including other phosphonate and carboxylic acid additives. Addition of a disulfonate anionic surfactant to a composition including HEDP (compare 3A and 3B) was observed to reduce removal rate and waviness (waviness was reduced from a normalized value of 108 to 95 at the expense of a normalized value of 136 to 116 for removal rate). Addition of a disulfonate anionic surfactant to a composition including DTPMPA (compare 3C and 3D) was observed to reduce removal rate and waviness (waviness was reduced from a normalized value of 107 to 101 at the expense of a normalized value of 151 to 128 for removal rate). It was observed that adding a disulfonate anionic surfactant to a composition including PBTC (compare 3E and 3F) resulted in a decrease in removal rate and waviness (waviness decreased from a normalized value of 132 to 95 at the expense of a normalized value of 181 for removal rate to 114). And it was observed that adding a disulfonate anionic surfactant to a composition including tartaric acid (compare 3G and 3H) resulted in a decrease in removal rate and waviness (waviness decreased from a normalized value of 116 to 100 at the expense of a normalized value of 138 for removal rate to 129).

[0064] Example 4

[0065] This example illustrates the use of other sulfonated surfactants (in addition to the ones used in Examples 1 and 2) The above synergistic effect was observed in polishing compositions (except C10L). As described in Example 1 above, each polishing composition includes 8.5 weight percent of colloidal silica having an average particle size of 30 nm and nitric acid sufficient to adjust the pH to 1.8. Polishing Composition 1F, Polishing Composition 1G, Polishing Composition 1I, and Polishing Composition 2E are described in Examples 1 and 2 above. Polishing Compositions 4A-4D and Polishing Composition 4F further include 0.12 weight percent TKPP, and Composition 4E further includes 0.08 weight percent TKPP. Polishing Compositions 4A to 4F further include 0.05 weight percent dodecylbenzene sulfonate (DDBS) (4A), C6L(4B), 3B2(4C), 2A1(4D), polyvinyl sulfonic acid (PVSA) (4E) and P9200 (modified polyacrylic acid) (4F). The amounts of these additives are listed in Table 4.

[0066] Six separate glass disks (substrates) were polished using each composition using a Binjing 9B double-sided polishing tool with the polishing conditions in Example 1 above. The polishing rate and surface waviness HMS_Wq were also determined as described above in Example 1. The results for removal rate and surface waviness are reported in Table 4. The results were normalized to the removal rate and surface waviness achieved using Polishing Composition 1A reported in Table 1.

[0067] Table 4

[0068]

[0069]

[0070] As shown in Table 4, the synergistic effects observed in Examples 1 and 2 above were also observed in polishing compositions including other sulfonate compounds. It was observed in Examples 4B, 4C, and 4D that the use of other disulfonate anionic surfactants in compositions including TKPP increased the removal rate from a normalized value of 152 to normalized values ​​of 178, 179, and 155, while decreasing the surface waviness from a normalized value of 120 to normalized values ​​of 109, 110, and 115. In Examples 4A and 4E, it was also observed that the addition of DDBS and PVSA to compositions including TKPP improved the removal rate and waviness. In Example 4A, the removal rate remained about the same (normalized values ​​of 153 vs. 152) and the surface waviness decreased from a normalized value of 120 to 105, while in Example 4E, the removal rate improved from a normalized value of 138 to 144 and the surface waviness decreased from a normalized value of 115 to 110. It was observed that the addition of non-sulfonate compounds ( The combination of P9200) and TKPP reduced the surface waviness from a normalized value of 120 to 108 (4F) at the expense of a reduction in removal rate from a normalized value of 152 to 120.

[0071] Example 5

[0072] This example illustrates the synergistic combination of a pyrophosphate compound and a quaternary ammonium compound in the disclosed polishing compositions. Each polishing composition includes 8.5 weight percent of colloidal silica having an average particle size of 30 nm and nitric acid sufficient to adjust the pH to 1.8 (except for Composition 5H and Composition 5I, which have nitric acid sufficient to adjust the pH to 2.3 and 2.8). Polishing Composition 1A and Polishing Composition 1G are as described above in Example 1. Compositions 5B-5I further include TKPP, while Compositions 5A-5I further include tetraethylammonium hydroxide in the amounts listed in Table 5 (all amounts are weight percent).

[0073] Six separate glass disks (substrates) were polished using each composition using a Binjing 9B double-sided polishing tool with the polishing conditions described in Example 1 above. The polishing rate and surface waviness HMS_Wq were also determined as described in Example 1 above. The results of the removal rate and surface waviness are reported in Table 5. The results were normalized to the removal rate and surface waviness achieved using Polishing Composition 1A reported in Table 1.

[0074] Table 5

[0075]

[0076]

[0077] As shown in Table 5, the addition of a quaternary amine compound (5A) (in the absence of TKPP) was observed to improve surface waviness at the expense of a reduced removal rate (waviness was reduced to a normalized value of 88 at the expense of a reduced removal rate to a normalized value of 82). As described above in Example 1, the addition of a pyrophosphate (1G) was observed to increase the removal rate at the expense of an increased surface waviness (removal rate was increased to a normalized value of 152, while waviness was also increased to a normalized value of 120). An unexpected synergistic interaction was observed in Compositions 5B, 5C, 5D, 5E, 5F, and 5G, where the addition of a quaternary amine (in this example, TEAH) to a polishing composition including a pyrophosphate compound significantly improved the removal rate. These compositions achieved an increase in removal rate compared to Composition 1G, with normalized values ​​of 168, 206, 211, 207, 205, and 207. It is particularly noted that Compositions 5F and 5G, which include relatively low amounts of TKPP (0.06 and 0.03 weight percent), achieve extremely high removal rates with normalized values ​​of 205 and 207 (compared to Compositions 1D and 1F in Example 1, which include amounts of TKPP of 0.02 and 0.08 weight percent). Compositions 5H and 5I show that increasing the pH to 2.3 and 2.8 reduces the surface waviness (to normalized values ​​of 132 and 125) without significantly reducing the removal rate (to normalized removal rates of 207 and 190).

[0078] Example 6

[0079] This example illustrates the synergistic effects observed with other quaternary amines (other than TEAH) in the polishing composition. As described above with respect to Example 5, each polishing composition included 8.5 weight percent of colloidal silica having an average particle size of 30 nm and nitric acid sufficient to adjust the pH to 1.8. Polishing Composition 1E and Polishing Composition 1G were as described above in Example 1. Composition 6A, Composition 6B, and Composition 6C further included TKPP in the amounts listed in Table 6 (all amounts are weight percent). Composition 6A and Composition 6B included alternative quaternary amines (benzyltributylammonium chloride and tetrabutylammonium hydroxide) in the amounts listed. Composition 6C included epsilon polylysine (a non-quaternary amine cationic compound).

[0080] Six separate glass disks (substrates) were polished using each composition using a Binjing 9B double-sided polishing tool with the polishing conditions in Example 1 above. The polishing rate and surface waviness HMS_Wq were also determined as described above in Example 1. The results for removal rate and surface waviness are reported in Table 6. The results were normalized to the removal rate and surface waviness achieved using Polishing Composition 1A reported in Table 1.

[0081] Table 6

[0082]

[0083] As described in Table 6, the synergistic effect observed in Example 5 above was observed with other quaternary amines (other than TEAH). It is noted that Compositions 6A and 6B achieved very high removal rates (normalized values ​​of 186 and 185) compared to Composition 1G (similar to Compositions 5B and 5C in Example 5). No synergistic effect was observed in Composition 5C (a non-quaternary ammonium compound), which was observed to have a lower removal rate (normalized values ​​of 105 vs. 130) and similar surface waviness than Composition 1E.

[0084] It should be understood that, unless otherwise specified herein, the citation of the range of values ​​herein is intended only to serve as a shorthand method for individually referring to each independent value within the range, and each independent value is incorporated into this specification as if it were individually listed herein. Unless otherwise specified herein or otherwise clearly contradictory to the context, all methods described herein can be performed in any suitable order. Unless otherwise stated, the use of any and all examples or illustrative language provided herein (e.g., "such as") is intended only to more preferably illustrate the present invention and not to limit the scope of the present invention. The language in this specification should not be considered to indicate that any unclaimed element is essential for practicing the present invention.

[0085] Preferred embodiments of the present invention are described herein, including the best mode known to the inventor for implementing the present invention. After reading the foregoing description, changes in those preferred embodiments may become apparent to those of ordinary skill in the art. The inventor expects that those skilled in the art will adopt the changes as appropriate, and the inventor intends to practice the present invention in a manner different from that specifically described herein. Therefore, if applicable law permits, the present invention includes all modifications and equivalents of the subject matter described in the claims attached hereto. In addition, unless otherwise noted herein or otherwise clearly contradictory to the context, the present invention encompasses any combination of the above elements in all possible variations thereof.

Claims

1. A chemical mechanical polishing composition comprising: Liquid carrier; abrasive particles in the liquid carrier; Pyrophosphate compounds; and Sulfonate compounds include sulfonate anionic surfactants or anionic polymers, the anionic polymers including sulfonic acid groups.

2. The composition of claim 1, wherein the abrasive particles comprise colloidal silica particles.

3. The composition of claim 1, wherein the average particle size of the abrasive particles is in the range of about 15 nm to about 40 nm.

4. The composition of claim 1 comprising from about 5 weight percent to about 15 weight percent of the abrasive particles at the point of use.

5. The composition of claim 1, wherein the pyrophosphate compound comprises tetrapotassium pyrophosphate (TKPP) or tetrasodium pyrophosphate (TSPP).

6. The composition according to claim 1, comprising: From about 0.01 weight percent to about 0.2 weight percent of said pyrophosphate compound at the point of use; and From about 0.01 weight percent to about 0.2 weight percent of the sulfonate compound at the point of use.

7. The composition of claim 6, wherein the sulfonate compound comprises a disulfonate anionic surfactant.

8. The composition of claim 7, wherein the sulfonate compound comprises an oxyalkyl diphenyl disulfonate anionic surfactant.

9. The composition of claim 1 having a pH in the range of about 1.5 to about 3.

10. The composition of claim 1, further comprising an anionic polymer.

11. The composition of claim 10, wherein the anionic polymer is a polyacrylate or polymethacrylate polymer.

12. A chemical mechanical polishing composition comprising: Liquid carrier; abrasive particles in the liquid carrier; Pyrophosphate compounds; Compounds comprising a quaternary ammonium group.

13. The composition according to claim 12, comprising: From about 0.01 weight percent to about 0.2 weight percent of said pyrophosphate compound at the point of use; and At the point of use about 0.01 weight percent to about 0.2 weight percent of the compound including a quaternary ammonium group.

14. The composition of claim 12, wherein the abrasive particles comprise colloidal silica particles.

15. The composition of claim 14, wherein the average particle size of the abrasive particles is in the range of about 15 nm to about 40 nm.

16. The composition of claim 14 comprising from about 5 weight percent to about 15 weight percent of the abrasive particles at the point of use.

17. The composition of claim 12, wherein the pyrophosphate compound comprises tetrapotassium pyrophosphate (TKPP) or tetrasodium pyrophosphate (TSPP).

18. The composition of claim 12, wherein the compound including a quaternary ammonium group comprises a tetramethylammonium group, a tetraethylammonium group, a tetrabutylammonium group, a benzyltributylammonium group, or a mixture thereof.

19. The composition of claim 18, wherein the compound comprising a quaternary ammonium group is tetraethylammonium hydroxide.

20. The composition of claim 12 having a pH in the range of about 1.5 to about 3.

21. A method for polishing a glass substrate, the method comprising: (a) contacting the substrate with the polishing composition according to claim 12; (b) moving the polishing composition and the polishing pad relative to the substrate; and (c) grinding the substrate to remove a portion of the substrate, thereby polishing the surface of the substrate.

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