WO2013152164A2

WO2013152164A2 - Slurry composition and method of use

Info

Publication number: WO2013152164A2
Application number: PCT/US2013/035227
Authority: WO
Inventors: Yue Liu
Original assignee: Ferro Corporation
Priority date: 2012-04-04
Filing date: 2013-04-04
Publication date: 2013-10-10
Also published as: WO2013152164A3

Abstract

The present invention provides an aqueous slurry composition for use in polishing glass and glass ceramic substrates. The composition includes abrasive particles and an agent that accelerates the removal rate of glass and glass ceramic substrates. The agent that accelerates removal rate of glass and glass ceramic substrates is a zwitterionic agent that includes sulfonate group and amine group, and which has a specific molecular structure as more fully described in the specification.

Description

SLURRY COMPOSITION AND METHOD OF USE

BACKGROUND OF INVENTION

[0001] Field of Invention

[0002] The present invention relates to a slurry composition for use in chemical- mechanical polishing applications and a method of using the slurry composition.

[0003] Description of Related Art

[0004] A variety of slurry compositions are known in the art for use in chemical- mechanical polishing glass and glass ceramic substrates. Such prior art slurry compositions generally consist of abrasive particles dispersed in deionized water and/or other liquids. Commonly utilized abrasive particles include, for example, cerium oxide, aluminum oxide, zirconium oxide, zirconium silicate, tin oxide, silicon dioxide and titanium oxide. Cerium oxide ("CeO₂") is most commonly used because it produces relatively higher removal rate when used to polish glass and glass ceramics.

[0005] As industry continues to seek improvement in production throughput in order to become more cost effective, increased removal rate using aforementioned abrasives is highly desirable. Homola, U.S. Pat. No. 6,221 ,1 19, discloses a method of polishing glass and glass-ceramic substrates using a slurry containing cerium oxide and sodium polyacrylate. Homola teaches that adding sodium polyacrylate to an aqueous cerium oxide slurry composition tends to increase the polishing rate.

[0006] Ferranti et al., U.S. Pat. No. 7,300,478 B2, discloses a method of polishing glass and glass ceramic substrates using a composition comprising cerium oxide and/or cerium oxide-containing mixed rare earth oxide abrasive particles, a polyacrylate, and an agent that retards hard settling. The agent that retards hard settling is preferably a polysaccharide such as xanthan gum, microcrystalline cellulose and/or sodium alginate, the latter of which may be treated with a divalent metal salt such as calcium carbonate.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an aqueous slurry composition that comprises abrasive particles and an agent that accelerates removal rate of glass and glass ceramic substrates. The agent that accelerates removal rate of glass and glass ceramic substrates is a zwitterionic agent comprising a sulfonate group and an amine group, which has the molecular structure (A), (B), or (C):

(A) H₂N - (CRiR₂)x - SO3 - M, where x = 1 only

(B) R₉HN - (CRi R₂)x - (CR₃R₄)_y - S0₃ - M. where x = 0 or 1 , y = 0 or 1 , and x + y > 0

(C) R₇R₈N - (CR₁ R₂)x -(CR₃R₄)_y -(CR₅R₆)z - S0₃ - M, where x = 0 or 1 , y = 0 or 1 , z = 0 or 1 , and x + y + z > 0 wherein, in each case, Ri, R₂, R3, R₄, R5, Re may be an alkyl, aryl, hydroxide, hydrogen, hetero atom ring, aryl ring, alkyl ring, or halogen; R₇, R₈, Rg may not be hydrogen, but alone or together may be a substituted or unsubstituted alkyl, amide, hydroxyl, aryl, hydroxide, hetero atom ring, aryl ring, alkyl ring, or halogen; M may be hydrogen, alkali or alkaline earth metal, or ammonium ion. The slurry composition according to this invention can be used to polish glass and glass ceramics at a high removal rate. The present invention also provides a method of polishing a glass or glass ceramic substrate using the slurry composition.

[0007] The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 shows the chemical structure of eight compounds, which were subjected to comparison testing for effectiveness as agents that accelerate the removal rate of glass and glass ceramic substrates in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] The slurry composition according to the present invention comprises deionized water, abrasive particles, and an agent that accelerates the removal rate of glass and glass ceramic substrates. Preferably, the slurry composition comprises from about 0.1 % to about 30% by weight, and more preferably from about 5% to about 15% by weight, of abrasive particles selected from the group consisting of cerium oxide, aluminum oxide, zirconium oxide, zirconium silicate, tin oxide, silicon dioxide and titanium oxide; and combinations thereof. The abrasive particles used in the slurry composition according to the invention preferably have an average particle size (D_mean) of from about 0.02 pm to about 7.0 pm. More preferably, the abrasive particles have an average particle size (D_mean) within the range of from about 0.15 pm to about 4.0 pm.

[0010] The agent that accelerates removal rate of glass and glass ceramic substrates is a zwitterionic agent comprising a sulfonate group and an amine group, which has the molecular structure (A), (B), or (C):

(A) H₂N - (CR₁R₂)x - SO₃ - M, where x = 1 only

(B) RgHN - (CR-i R₂)x - (CR₃R₄)_y - SO₃ - M. where x = 0 or 1 , y = 0 or 1 , and x + y > 0

(C) R₇R₈N - (CR R₂)x -(CR₃R₄)_y -(CR₅R₆)_Z - SO₃ - M, where x = 0 or 1 , y = 0 or 1 , z = 0 or 1 , and x + y + z > 0 wherein, in each case, R-i, R₂, R₃, R₄, R₅, R₆ may be an alkyl, aryl, hydroxide, hydrogen, hetero atom ring, aryl ring, alkyl ring, or halogen; R₇, R₈, Rg may not be hydrogen, but alone or together may be a substituted or unsubstituted alkyl, amide, hydroxyl, aryl, hydroxide, hetero atom ring, aryl ring, alkyl ring, or halogen; M may be hydrogen, alkali or alkaline earth metal, or ammonium ion.

[001 1 ] The slurry composition preferably comprises one or more of said zwitterionic agents in an amount within the range of from about 0.05% to about 5% by weight of the slurry. More preferably, slurry composition preferably comprises one or more zwitterionic agents in an amount within the range of from about 0.1 % to about 1 % by weight of the total solids present in the slurry composition.

[0012] Suitable zwitterionic agents for use as polishing accelerants in the invention include, for example, aminomethanesulfonic acid ("AMS"), 2- [tris(hydroxymethyl)methylamino]-1 -ethanesulfonic acid ("TES"), N-(2-acetamido)-2- aminoethanesulfonic acid ("ACES"), N-(carbamoylmethyl)taurine, N-cyclohexyl-3- aminopropanesulfonic acid, N-cyclohexyl-2-aminoethanesulfonic acid, N- tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid, 2-hydroxy-N- tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid, 2-(N- morpholino)ethanesulfonic acid monohydrate, 2-morphoiinoethanesulfonic acid monohydrate ("MES"), N_JN-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid ("BES"), N,N-bis(2-hydroxyethyl)taurine, N-(2-acetamido)iminodiacetic acid, 3-[4-(2- hydroxyethyl)-1 -piperazinyl]propanesulfonic acid, 2-[4-(2-hydroxyethyl)-1- piperazinyl]ethanesulfonic acid, 2-hydroxy-3-[4-(2-hydroxyethyl)-1 - piperazinyl]propanesulfonic acid, 3-morpholinopropanesulfonic acid ("MOPS"), 2- hydroxy-3-morpholinopropanesulfonic acid, piperazine-1 ,4-bis(2-ethanesulfonic acid), piperazine-1 ,4-bis(2-ethanesulfonic acid), and sesquisodium salt piperazine-1 , 4-bis(2- hydroxy-3-propanesulfonic acid). The most preferred zwitterionic accelerants in the present invention are aminomethanesulfonic acid ("AMS"), 2- [tris(hydroxymethyl)methylamino]-1 -ethanesuifonic acid ("TES"), N-(2-acetamido)-2- aminoethanesulfonic acid ("ACES"), 2-morpholinoethanesulfonic acid monohydrate ("MES"), N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid ("BES"), and 3- morpholinopropanesulfonic acid ("MOPS").

[0013] In one preferred embodiment the composition for polishing glass and glass- ceramics comprises zirconium oxide abrasive particles, morpholinopropanesulfonic acid ("MOPS"), and water specifically for producing an increase in removal rate for glass and glass-ceramics polishing. The zirconium oxide abrasive particles in this embodiment preferably have a average particle size (D_mean) ranging from about 0.02 pm to about 1.0 pm, with a maximum size of less than about 10 pm, with the optimal average particle size ranging from 0.3 pm - 0.7 pm. The zirconium oxide abrasive particles can be present in the slurry in an amount of from about 0.1 % to about 30% by weight of the slurry, with the optimal range being from about 5% to about 15% by weight of the slurry. The amount of morpholinopropanesulfonic acid ("MOPS") can be present in the slurry in a concentration ranging between about 0.05% to about 1 .0% of the slurry weight, preferably at a concentration of 0.15% to about 0.35%. An aqueous slurry containing zirconium oxide abrasive particles and morpholinopropanesulfonic acid ("MOPS") in this preferred embodiment exhibits increased removal rates of glass and glass-ceramics substrates over a pH range of about 3 to about 7.

[0014] Preferably, the pH of the aqueous slurry is within the range of about 4.5 to about 5.5. The pH of the aqueous slurry can be adjusted by the addition of acid or base. Nitric acid is the presently preferred acid for decreasing the pH of the aqueous slurry, and ammonium hydroxide or tetramethylammonium hydroxide are preferred bases for increasing the pH of the aqueous slurry. It will be appreciated that the selection of a pH modifier is not critical, and that other acids and bases can be used in the practice of the invention. The slurry may also contain other additives, surfactants, pH buffers, anti-foaming agents, and dispersing agents, which are well known.

[0015] The present invention also provides a method for increasing the removal rate of glass and glass ceramics from a substrate, said method comprising:

providing a slurry composition comprising deionized water, abrasive particles, and a zwitterionic agent comprising a sulfonate group and an amine group, which has the molecular structure (A), (B), or (C):

(A) H₂N - (CR₁R₂)x - SO₃ - M, where x = 1 only

(B) RgHN - (CRi R₂)x - (CR₃R₄)_y - SO₃ - M. where x = 0 or 1 , y = 0 or 1 , and x + y > 0

(C) R₇R₈N - (CRi R₂)x -(CR₃R₄)_y -(CR₅R₆)_Z - SO₃ - M, where x = 0 or 1 , y = 0 or 1 , z = 0 or 1 , and x + y + z > 0 wherein, in each case, R-i, R₂, R₃, R₄, R₅, R₆ may be an alkyl, aryl, hydroxide, hydrogen, hetero atom ring, aryl ring, alkyl ring, or halogen; R , R₈, Rg may not be hydrogen, but alone or together may be a substituted or unsubstituted alkyl, amide, hydroxyl, aryl, hydroxide, hetero atom ring, aryl ring, alkyl ring, or halogen; M may be hydrogen, alkali or alkaline earth metal, or ammonium ion; and

polishing the substrate with the slurry composition.

[0016] Polyacrylates used in prior art slurry compositions are polymers and often cause slurry viscosity to increase. Furthermore, polyacrylates do not increase the removal rate of glass and glass ceramics when polishing with zirconium oxide abrasive particles. The zwitterionic agents described in the present invention do show a significant increase in the removal rate of glass and glass ceramics, particularly when polishing with zirconium oxide abrasive particles. Preferably, a slurry composition according to the invention does not contain any polyacrylates. Thus, an advantage of a slurry composition according to the invention as compared to prior art slurry

compositions that contain polyacrylates is that the slurry composition according to the invention does not present hard settling issues. In addition, the zwitterionic agents used in this invention are not polymers and therefore do not cause slurry viscosity to increase.

[0017] The method according to the present invention comprises introducing a slurry composition between a polishing pad and a substrate comprising glass or glass ceramic to be polished, and pressing the same into contact and moving the same relative to each other, wherein the slurry composition comprises deionized water, abrasive particles, and one or more zwitterionic polishing accelerant agents described above.

[0018] The method of the invention can be used to planarize glass and glass ceramic substrates used for electronic glass applications. Typical applications include the fabrication of amorphous glass memory hard disks, glass and glass-ceramic memory hard disks, and all types of liquid crystal display (LCD) glass substrates, as well as quartz for making photomasks for semiconductor photolithography process, cover glass for electronic devises such as cell phones and smart phones, glass for optical devises such as microscopes, telescopes, and digital cameras.

[0019] The following examples are intended only to illustrate the invention and should not be construed as imposing limitations upon the claims. EXAMPLE 1

[0020] Table 1 shows the polishing rate of a glass hard disk substrate as a function of the concentration of morpholinopropanesulfonic acid ("MOPS") in zirconium oxide abrasive slurries. It can be appreciated that in the absence of MOPS, a slurry containing 10% zirconium oxide (D_mean = 0.50 pm) removes glass hard disk at a rate of 35.0 mg/10 minutes (control). In the presence of MOPS, the glass hard disk removal rate is much greater, and reaches a removal rate as high as 51 .0 mg/10 minutes when the slurry contains 10% zirconium oxide and 0.25% MOPS. Therefore, MOPS clearly acts in such a way as to increase glass hard disk removal rate.

TABLE 1

EXAMPLE 2

[0021] Table 2 shows the polishing rates of several different types of glass and glass ceramic substrates using slurries that contain 10% zirconium oxide abrasives with and without the presence of 0.25% MOPS. In Table 2, the term "Hard Disk" references an alkali-free lithium aluminosilicate glass-ceramic material, the term "TFT LCD" references an alkali-free silicate glass-ceramic, the term "BK-7" references a borosilicate glass, the term "Soda Lime" references an alkali-containing glass, the term "Fused Silica" references a pure silicon dioxide material and the term "Glass Ceramic" references an alkali aluminum and magnesium containing silicate material. It can be seen that the presence of MOPS does significantly increase the removal rate using zirconium oxide abrasives on several different types of glass and glass ceramic substrates. TABLE 2

EXAMPLE 3

[0022] This example demonstrates that only zwitterionic agents comprising a sulfonate group and an amine group, which have a molecular structure according to (A), (B) or (C) as defined below, provide an increase in acceleration rate for glass and glass ceramic polishing:

(A) H₂N - (CR₁R₂)x - S0₃- M, where x = 1 only

(B) RgHN - (CR₁R₂)x - (CR₃R₄)_y - S0₃ - M. where x = 0 or 1 , y = 0 or 1 , and x + y > 0

(C) R₇R₈N - (CR₁R₂)x -(CR₃R₄)_y -(CR₅R₆)_Z - S0₃ - M, where x = 0 or 1 , y = 0 or 1 , z = 0 or 1 , and x + y + z > 0 wherein, in each case, R-i , R₂, R₃, R₄, R₅, R₆ may be an alkyl, aryl, hydroxide, hydrogen, hetero atom ring, aryl ring, alkyl ring, or halogen; R₇, R₈, R₉ may not be hydrogen, but alone or together may be a substituted or unsubstituted alkyl, amide, hydroxyl, aryl, hydroxide, hetero atom ring, aryl ring, alkyl ring, or halogen; M may be hydrogen, alkali or alkaline earth metal, or ammonium ion.

[0023] Fig. 1 shows the chemical structure of eight compounds, which were subjected to comparison testing for effectiveness as agents that accelerate the removal rate of glass and glass ceramic substrates. With reference to Fig. 1 , neither "Sulfamic acid" nor "Taurine" have a molecular structure according to (A), (B) or (C), as defined above. "Sulfamic acid" would have the structure (A) if x was permitted to be 0, and "Taurine" would have the structure (A) if x was permitted to be 2, but structure (A) requires that x = 1 , which is met by aminomethanesulfonic acid ("AMS").

[0024] For purposes of comparison, five other agents that have a molecular structure according to (A), (B) or (C), as defined above were also tested, namely: N-(2- acetamido)-2-aminoethanesulfonic acid ("ACES"); 2-[tris(hydroxymethyl)methylaminoj- 1 -ethanesulfonic acid ("TES"); 2-morpholinoethanesulfonic acid monohydrate ("MES"); N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid ("BES"); and 3- morpholinopropanesulfonic acid ("MOPS").

[0025] In Table 3, the slurry compositions containing sulfamic acid and taurine showed lower removal rates than a control slurry that contained now zwitterionic agents. However, slurries containing zwitterionic agents having a molecular structure according to (A), (B) or (C), as defined above, did increase the removal rate.

TABLE 3

EXAMPLE 4

[0026] This example illustrates that the zwitterionic agents described in the present invention work as polishing accelerants for glass and glass-ceramics when polished with cerium oxide slurries. As demonstrated in Table 4, the removal rate of glass hard disk increases to as high as 1 16% as comparing to the removal rate from a slurry without zwitterionic accelerant (control). The cerium oxide particles used for polishing slurries in this example have an average particle size (D_mean) of 1 .25 μηη. TABLE 4

[0027] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and illustrative examples shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims

What is claimed is:

Claim 1 (original): An aqueous slurry composition comprising:

abrasive particles selected from the group consisting of cerium oxide, aluminum oxide, zirconium oxide, zirconium silicate, tin oxide, silicon dioxide, titanium oxide and combinations thereof; and

one or more zwitterionic agents comprising a sulfonate group and an amine

group, which have a molecular structure (A), (B), or (C):

(A) H₂N - (CRi R₂)x - S0₃ - M, where x = 1 only

(B) RgHN - (CR-i R₂)x - (CR₃R₄)_y - S0₃ - M. where x = 0 or 1 , y = 0 or 1 , and x + y > 0

(C) R₇R₈N - (CRi R₂)x -(CR₃R₄)_y -(CR₅R₆)_Z - S0₃ - M, where x = 0 or 1 , y = 0 or 1 , z = 0 or 1 , and x + y + z > 0 wherein, in each case, R-i , R₂, R3, R₄, R5, R6 may be an alkyl, aryl, hydroxide, hydrogen, hetero atom ring, aryl ring, alkyl ring, or halogen; R₇, R₈, Rg may not be hydrogen, but alone or together may be a substituted or unsubstituted alkyl, amide, hydroxyl, aryl, hydroxide, hetero atom ring, aryl ring, alkyl ring, or halogen; M may be hydrogen, alkali or alkaline earth metal, or ammonium ion.

Claim 2 (original): The aqueous slurry composition according to claim 1 wherein the one or more zwitterionic agents is selected from the group consisting of:

aminomethanesulfonic acid, N-(2-acetamido)-2-aminoethanesulfonic acid, 2- [tris(hydroxymethyl)methylamino]-1-ethanesulfonic acid, 2-morpholinoethanesulfonic acid monohydrate, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, and 3- morpholinopropanesulfonic acid. Claim 3 (original): The aqueous slurry composition according to claim 1 wherein the abrasive particles have an average particle size (D_mean) of from about 0.02 pm to about 7.0 μιη.

Claim 4 (original); The aqueous slurry composition according to claim 1 wherein the abrasive particles are zirconium oxide.

Claim 5 (original): The aqueous slurry composition according to claim 1 wherein the abrasive particles are cerium oxide.

Claim 6 (original): A method of polishing a glass or glass-ceramic substrate comprising introducing an aqueous slurry composition between a polishing pad and the substrate when the polishing pad and substrate are pressed into contact with each other and moving relative to each other, wherein the aqueous slurry composition comprises: abrasive particles selected from the group consisting of cerium oxide, aluminum oxide, zirconium oxide, zirconium silicate, tin oxide, silicon dioxide, titanium oxide and combinations thereof; and

one or more zwitterionic agents comprising a sulfonate group and an amine

group, which has the molecular structure (A), (B), or (C):

(A) H₂N - (CR R₂)x - SO₃- M, where x = 1 only

(B) R₉HN - (CRiR₂)x - (CR₃R₄)_y - S0₃ - M. where x = 0 or 1 , y = 0 or 1 , and x + y > 0

(C) R₇R₈N - (CRi R₂)x -(CR₃R₄)_y -(CR₅R₆)z - SO₃ - M, where x = 0 or 1 , y = 0 or 1 , z = 0 or 1 , and x + y + z > 0 wherein, in each case, R-i, R₂, R₃, R₄, R₅, R₆ may be an alkyl, aryl, hydroxide, hydrogen, hetero atom ring, aryl ring, alkyl ring, or halogen; R₇, R₈, R₉ may not be hydrogen, but alone or together may be a substituted or unsubstituted alkyl, amide, hydroxyl, aryl, hydroxide, hetero atom ring, aryl ring, alkyl ring, or halogen; M may be hydrogen, alkali or alkaline earth metal, or ammonium ion.

Claim 7 (original): The method according to claim 6 wherein the one or more zwitterionic agents is selected from the group consisting of: aminomethanesulfonic acid, N-(2-acetamido)-2-aminoethanesulfonic acid, 2-[tris(hydroxymethyl)methylamino]-1 - ethanesulfonic acid, 2-morpholinoethanesulfonic acid monohydrate, N,N-bis(2- hydroxyethyl)-2-aminoethanesulfonic acid, and 3-morpholinopropanesulfonic acid

Claim 8 (original): The method according to claim 6 wherein the abrasive particles have an average particle size (D_mean) of from about 0.02 pm to about 7.0 pm.

Claim 9 (original): The method according to claim 6 wherein the abrasive particles are zirconium oxide.

Claim 10 (original): The method according to claim 6 wherein the abrasive particles are cerium oxide.

Claim 1 1 (original): The method according to any of claims 6-10 wherein said substrate comprises a memory disk.