Polishing composition and method of polishing a substrate having enhanced defect reduction

Abstract

An aqueous alkaline chemical mechanical polishing composition comprising a quaternary ammonium compound having a phenyl group, which enables enhanced defect reduction on silicon oxide substrates and enables good silicon oxide removal rates during chemical mechanical polishing.

Description

Technical Field

[0001] This invention relates to an alkaline polishing composition and a method for polishing a substrate with enhanced defect reduction and a good dielectric removal rate. More specifically, this invention relates to an alkaline polishing composition and a method for polishing a substrate with enhanced defect reduction and a good dielectric removal rate, wherein the polishing composition comprises a quaternary ammonium compound having a phenyl group to enhance defect reduction on a substrate comprising a silicon oxide dielectric, and wherein at least some of the silicon oxide is removed from the substrate. Prior Technology

[0002] In the fabrication of integrated circuits and other electronic devices, multiple layers of conductive, semiconducting, and dielectric materials are deposited onto or removed from the surface of semiconductor wafers. Several deposition techniques can be used to deposit thin layers of conductive, semiconducting, and dielectric materials. Common deposition techniques in modern processing include physical vapor deposition (PVD) (also known as sputtering), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and electrochemical plating (ECP).

[0003] As material layers are deposited and removed sequentially, the top surface of the wafer becomes non-planar. Because subsequent semiconductor processing (e.g., metallization) requires a flat surface on the wafer, wafer planarization is necessary. Planarization can be used to remove unwanted surface topography and surface defects, such as rough surfaces, aggregated material, lattice damage, scratches, and contaminated layers or materials.

[0004] Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize substrates, such as semiconductor wafers. In conventional CMP, the wafer is mounted on a carrier assembly and positioned to contact a polishing pad in the CMP equipment. The carrier assembly applies controlled pressure to the wafer, pressing it against the polishing pad. The pad is moved (e.g., rotated) relative to the wafer by an external driving force. Simultaneously, a polishing composition ("slurry") or other polishing fluid is provided between the wafer and the polishing pad. Thus, the wafer surface is polished and planarized by the chemical and mechanical action of the pad surface and the slurry.

[0005] Some advanced device designs require enhanced silicon oxide removal efficiency and reduced scratch defects at lower point-of-use (POU) abrasive weight percent to improve the overall polishing process and product yield percent of polished compositions. As the size of structures on semiconductor devices continues to shrink, performance standards once acceptable for planarization and reducing defects in polished dielectric materials are becoming increasingly unacceptable. Scratches that were once considered acceptable are now yield limitations.

[0006] Therefore, there is a need for polishing compositions and polishing methods that exhibit the desired planarization efficiency, uniformity, and dielectric removal rate while minimizing defects such as scratches. Summary of the Invention

[0007] This invention provides a chemical mechanical polishing composition comprising: water; an abrasive; a pH adjuster as needed; a biocidal agent as needed; a pH greater than 7; and a quaternary ammonium compound having formula (I): (I), R1, R2 and R3 are independently selected from the group consisting of phenyl, benzyl and straight-chain or branched C1-C5 alkyl groups; and the X- group consists of anions selected from the group consisting of Br-, Cl-, I-, F- and OH-.

[0008] The present invention also provides a chemical mechanical polishing composition comprising: water; 0.1 to 40 wt% abrasive; a pH adjuster as needed; a biocide as needed; a pH greater than 7; and 0.001 to 1 wt% a quaternary ammonium compound having formula (I). (I), R1, R2 and R3 are independently selected from the group consisting of phenyl, benzyl and straight-chain or branched C1-C5 alkyl groups; and the X- group consists of anions selected from the group consisting of Br-, Cl-, I-, F- and OH-.

[0009] The present invention further provides a chemical mechanical polishing composition comprising: water; 5 to 25 wt% colloidal silica abrasive; a pH adjuster; a biocide as needed; a pH of 8-13; and 0.001 to 1 wt% of a quaternary ammonium compound having formula (I). (I), R1, R2 and R3 are independently selected from the group consisting of phenyl, benzyl and straight-chain or branched C1-C5 alkyl groups; and the X- group consists of anions selected from the group consisting of Br-, Cl-, I-, F- and OH-.

[0010] This invention provides a method for chemical mechanical polishing of a substrate, the method comprising: providing a substrate comprising silicon oxide; providing a chemical mechanical polishing composition comprising: water; an abrasive; a pH adjuster as needed; a biocidal agent as needed; a pH greater than 7; and a quaternary ammonium compound having (I): (I), R1, R2, and R3 are independently selected from the group consisting of: phenyl, benzyl, and straight-chain or branched C1-C5 alkyl groups; and the X- group consists of anions selected from the group consisting of Br-, Cl-, I-, F-, and OH-. A chemical mechanical polishing pad having a polished surface is provided; dynamic contact is generated at the interface between the polished surface of the chemical mechanical polishing pad and the substrate using a downward pressure of 3 to 35 kPa; and a chemical mechanical polishing composition is dispensed onto the chemical mechanical polishing pad at or near the interface between the chemical mechanical polishing pad and the substrate; and wherein a portion of the silicon oxide is removed from the substrate.

[0011] The chemical mechanical polishing composition and method of the present invention enable enhanced defect reduction and enable good silicon oxide removal rates. Simple Explanation of the Diagram

[0012] none Implementation

[0013] As used throughout this specification, unless the context otherwise indicates, the following abbreviations have the following meanings: L = liter; mL = milliliter; kPa = kilopascal; Å = angstrom; nm = nanometer; min = minute; rpm = revolutions per minute; wt% = weight percentage; RR = removal rate; mmol = millimole; Br- = bromide ion; Cl- = chloride ion; I- = iodide ion; F- = fluoride ion; OH- = hydroxide ion; PS = polishing slurry of the present invention; PC = comparative polishing slurry.

[0014] The terms "chemical mechanical polishing" or "CMP" refer to a process that polishes a substrate solely by chemical and mechanical forces, and are distinguished from electrochemical mechanical polishing (ECMP), in which an electrical bias voltage is applied to the substrate. In this specification, the terms "quaternary ammonium compound" and "quaternary ammonium salt" are used interchangeably because quaternary ammonium compounds are water-soluble or water-dispersible salts. The term "TEOS" refers to silicon oxide formed by the decomposition of tetraethyl orthosilicate (Si(OC₂H₅)₄). Throughout this specification, the terms "composition" and "slurry" are used interchangeably. The term "halogen ion" refers to chloride, bromide, fluoride, and iodide ions. The term "a / an" refers to both the singular and plural. Unless otherwise stated, all percentages are by weight. All numerical ranges are inclusive and can be combined in any order, except where it is logical to limit the range to a maximum sum of 100%.

[0015] The chemical mechanical polishing composition of the present invention can be used for polishing substrates containing silicon oxide. The chemical mechanical polishing composition comprises (preferably) the following: water; abrasive; a pH adjuster as needed; a biocidal agent as needed; a pH greater than 7; and a quaternary ammonium compound having formula (I) for reducing defects and increasing the removal rate of silicon oxide from the substrate: (I) R1, R2, and R3 are independently selected from the group consisting of phenyl, benzyl, and straight-chain or branched C1-C5 alkyl groups; and the X- group consists of anions selected from the group consisting of Br-, Cl-, I-, F-, and OH-. The mixture of quaternary ammonium compounds of the present invention may also be included in the chemimechanical polishing composition of the present invention.

[0016] The term "enhanced silicon oxide removal rate" used in this document to describe the silicon oxide removal rate (measured in Å / min) obtained by polishing a substrate using a chemical mechanical polishing composition containing a quaternary ammonium compound with phenyl groups means satisfying at least the following formula: A > A 0 Wherein A represents the silicon oxide removal rate (in Å / min) of the chemical mechanical polishing composition containing the claimed quaternary ammonium compound used in the method of polishing the substrate of the present invention, measured under the polishing conditions described in the examples; A0 represents the silicon oxide removal rate (in Å / min) obtained under the same conditions using only the present silicon dioxide abrasive.

[0017] The term "improved polishing defect rate performance," used herein to describe the defect rate performance obtained by including a quaternary ammonium compound having formula (I) in a chemical mechanical polishing composition used in the chemical mechanical polishing method of the present invention, means satisfying at least the following formula: X < X 0 Wherein X refers to the defect rate (i.e., CMP / hydrogen fluoride (HF) after scratches or defects) of a chemical mechanical polishing composition containing the substances used in the method of the present invention, as measured under the polishing conditions stated in the examples; and X0 refers to the defect rate (i.e., CMP / hydrogen fluoride after scratches or defects) obtained only with the present silicon dioxide abrasive under the same conditions.

[0018] Preferably, the chemical mechanical polishing composition of the present invention comprises a quaternary ammonium compound having formula (I) in an amount of 0.001 to 1 wt%, more preferably from 0.1 to 1 wt%, and most preferably from 0.1 to 0.5 wt%.

[0019] Preferably, the quaternary ammonium compound of the present invention has formula (I): (I), R1, R2, and R3 are independently selected from the group consisting of phenyl and C1-C2 alkyl groups, and X- is an anion selected from the group consisting of Br-, Cl-, and OH-. More preferably, R1, R2, and R3 are independently selected from the group consisting of C1-C2 alkyl groups, and X- is a halide ion selected from Br- and Cl-. Most preferably, R1, R2, and R3 are C1 alkyl or methyl (-CH3), and X- is a halide ion selected from Br- and Cl-. A preferred mixture of quaternary ammonium compounds may also be included in the chemimechanical polishing composition of the present invention.

[0020] Exemplary quaternary ammonium compounds among the aforementioned preferred quaternary ammonium compounds are quaternary ammonium salts selected from the group consisting of phenyltrimethylammonium chloride, phenyltrimethylammonium bromide, and phenyltrimethylammonium hydroxide. Most preferably, the quaternary ammonium salt is selected from the group consisting of phenyltrimethylammonium chloride and phenyltrimethylammonium bromide. Mixtures of such quaternary ammonium salts may be included in the chemical mechanical polishing composition of the present invention.

[0021] The water contained in the chemical mechanical polishing composition used in the chemical mechanical polishing method of the present invention is preferably at least one of deionized water and distilled water, in order to limit incidental impurities.

[0022] The chemical mechanical polishing composition used in the chemical mechanical polishing method of the present invention contains: 0.1 to 40 wt% abrasive; preferably 5 to 30 wt%, more preferably 10 to 20 wt% abrasive. The abrasive used preferably has an average particle size of < 200 nm; more preferably 75 to 150 nm; and most preferably 100 to 150 nm.

[0023] The abrasives used in the chemical mechanical polishing composition for use in the chemical mechanical polishing method of the present invention include, for example, inorganic oxides, inorganic hydroxides, inorganic hydroxide oxides, metal borides, metal carbides, metal nitrides, polymer particles, and mixtures comprising at least one of the foregoing. Suitable inorganic oxides include, for example, silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), zirconium oxide (ZrO₂), cerium dioxide (CeO₂), manganese oxide (MnO₂), titanium oxide (TiO₂), or combinations thereof. Modified forms of these inorganic oxides, such as organic polymer-coated inorganic oxide particles and inorganic coated particles, may also be used if desired. Suitable metal carbides, borides, and nitrides include, for example, silicon carbide, silicon nitride, silicon carbonitride (SiCN), boron carbide, tungsten carbide, zirconium carbide, aluminum boride, tantalum carbide, titanium carbide, or combinations thereof.

[0024] The preferred abrasive material used in the chemical mechanical polishing composition for use in the chemical mechanical polishing method of the present invention is colloidal silica. Preferably, the colloidal silica used contains at least one of precipitated silica and agglomerated silica. Preferably, the colloidal silica used has an average particle size of < 200 nm, more preferably 75 to 150 nm, and most preferably 100 to 150 nm; and constitutes 0.1 to 40 wt%, preferably 5 to 30 wt%, and more preferably 10 to 20 wt% of the chemical mechanical polishing composition. Examples of commercially available colloidal silica include Klebosol™ II 1630 colloidal silica with an average particle size of 139 nm; Klebosol™ II 1630 colloidal silica with an average particle size of 145 nm; and Klebosol™ II 1730 colloidal silica with a particle size of 130 nm, all manufactured by Merck KgAA in Darmstadt, Germany, and all available from DuPont.

[0025] If necessary, the chemimechanical polishing composition may contain a biocide, such as KORDEK™ MLX (9.5% - 9.9% methyl-4-isothiazolin-3-one, 89.1% - 89.5% water and ≤ 1.0% related reaction products) or KATHON™ ICP III containing the active ingredients 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, each manufactured by International Flavors & Fragrances, Inc. (KATHON and KORDEK are trademarks of International Flavors & Fragrances, Inc.).

[0026] When the chemical mechanical polishing composition of the present invention contains a biocide, the biocide is contained in an amount of 0.0001 wt% to 0.1 wt%, preferably 0.001 wt% to 0.05 wt%, more preferably 0.001 wt% to 0.01 wt%, and even more preferably 0.001 wt% to 0.005 wt%.

[0027] The chemical mechanical polishing composition used in the chemical mechanical polishing method of the present invention has a pH of >7, preferably 7 to 12, and more preferably 10 to 11.

[0028] The chemical mechanical polishing composition used may, as needed, contain one or more pH adjusters to maintain the pH within an optimal range. Preferably, the pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide, and ammonium salts, such as ammonium halides or ammonium nitrate.

[0029] In the chemical mechanical polishing method of the present invention, the substrate being polished includes silicon oxide. The silicon oxide in the substrate includes, but is not limited to, borosilicate glass (BPSG), plasma-reinforced tetraethyl orthosilicate (PETEOS), thermal oxides, undoped silicate glass, and high-density plasma (HDP) oxides.

[0030] The chemical mechanical polishing pad used in the chemical mechanical polishing method of the present invention can be any suitable polishing pad known in the art. The chemical mechanical polishing pad can be selected from woven and nonwoven polishing pads as needed. The chemical mechanical polishing pad can be made of any suitable polymer with different densities, hardness, thickness, compressibility, and modulus. The chemical mechanical polishing pad can be slotted and perforated as desired.

[0031] The quaternary ammonium compound having formula (I) included in the chemical mechanical polishing composition used in the chemical mechanical polishing method of the present invention results in improved polishing defect rate performance. Preferably, including the quaternary ammonium compound having formula (I) in the chemical mechanical polishing composition provides a >50% reduction in polishing defect rate (i.e., CMP / hydrogen fluoride post-scratches) as measured under the polishing conditions stated in the examples. That is, preferably, the following formula is satisfied: (X0 - X) / X0 * 100 > 50; Wherein X is the polishing defect rate (i.e., CMP / hydrogen fluoride post-scratches or defects) of the chemical mechanical polishing composition containing an asymmetric quaternary ammonium compound according to formula (I) and used in the method of the present invention, as measured under the polishing conditions stated in the examples; and X0 is the polishing defect rate (i.e., CMP / hydrogen fluoride post-scratches or defects) obtained under the same conditions using only the present silicon dioxide abrasive.

[0032] The chemical mechanical polishing composition used in the chemical mechanical polishing method of the present invention enables operation at low nominal polishing pad pressures (e.g., 3 to 35 kPa). The low nominal polishing pad pressure improves polishing performance by reducing scratches and other undesirable polishing defects and minimizes damage to fragile materials.

[0033] The following examples are intended to illustrate the invention, but are not intended to limit its scope.

[0034] In the following examples, unless otherwise indicated, the temperature and pressure conditions are ambient temperature and standard pressure.

[0035] The following materials were used in subsequent examples: Polishing removal rate experiments were conducted on 8-inch blanket-coated wafers. An Applied Materials Mirra® polisher was used for Example 1, and an Applied Materials Reflexion® polisher was used for Example 2. Polishing Example 1 used a VisionPad 5000 / K7™ polyurethane polishing pad, and polishing Example 2 used an IC1010 polyurethane polishing pad (both commercially available from Rohm and Haas Electronic Materials CMP Inc.), with a downforce of 20.7 kPa (3 psi), a chemical mechanical polishing slurry flow rate of 150 mL / min in Example 1 and 250 mL / min in Example 2, a stage rotation speed of 93 rpm, and a carriage rotation speed of 87 rpm. The removal rate was determined by measuring the film thickness before and after polishing using a KLA-Tencor FX200 measuring instrument. The defect rate performance reported in the examples was determined using scanning electron microscopy after washing following hydrogen fluoride polishing (“Pst HF”). All TEOS wafers after Pst-HF washing were inspected using the Surfscan® SP2 defect inspection system, available from KLA-Tencor. Defect information (including its coordinates on the wafer) was recorded in KLARF (KLA Results File) and then transferred to the eDR-5200 defect review system, also available from KLA-Tencor. A random sample of 100 defect images was selected and reviewed using the eDR-5200 system. These 100 images were classified into various defect types, such as chatter marks (scratches), particles, and pad fragments. Based on the classification results from these 100 images, the total number of scratches on the wafers was determined. [Example] [1] [Chemical mechanical polishing composition] [TEOS RR] [And defect reduction] []

[0036] Aqueous chemical mechanical polishing slurries were prepared as shown in Table 1 below. A 2 wt% KOH aqueous solution was added to each slurry to maintain the desired pH. [Table 1] [Pulp] [Abrasive] [(] [wt%] [)] [Tetraethyl] [-] [Ammonium hydroxide] [(] [wt%] [)] [Phenylacetyl] [-] [Ammonium chloride] [(] [wt%] [)] [pH] PC-1 16 0 0 10.7 PC-2 16 0.34 0 10.7 PS-1 16 0 0.4 10.7 Abrasive: Klebosol™ II 1630 colloidal silicon dioxide with an average particle size of 139 nm, manufactured by Merck Group in Darmstadt, Germany, and available from DuPont. [Table 2] [Pulp] [TEOS RR] [Pst-HF] [Defect Count] [Pst-HF] [Scratches] PC-1 2868 638 422 PC-2 2938 247 161 PS-1 2949 229 101

[0037] Compared to the two comparative pastes PC-1 and PC-2, the paste PS-1 of the present invention exhibits improved TEOS RR, reduced defect count, and reduced scratches. [Example] [2] [Chemical mechanical polishing composition] [TEOS RR] [And defect reduction]

[0038] Aqueous chemical mechanical polishing slurries were prepared as shown in Table 3 below. A 2 wt% KOH aqueous solution was added to each slurry to maintain the desired pH. [Table 3] [Pulp] [Abrasives()] [wt%] [)] [Phenylacetyltrimethylammonium chloride] [pH] PC-3 15.5 0 10.7 PS-2 15.5 0.36 10.7 PS-3 15.5 0.24 10.7 PS-4 15.5 0.48 10.7 Abrasive: Klebosol™ II 1630 colloidal silicon dioxide with an average particle size of 139 nm, manufactured by Merck Group in Darmstadt, Germany, and available from DuPont. [Table 4] [Pulp] [TEOS RR] [Pst-HF] [Scratches] PC-3 2899 311 PS-2 3047 89 PS-3 3001 81 PS-4 3090 58

[0039] Compared to PC-3, which only contains abrasive and water, the slurries PS-2, PS-3 and PS-4 of the present invention, which contain phenyltrimethylammonium chloride, exhibit enhanced TEOS RR and reduced scratches.

[0040] none

[0041] none

Claims

1. A chemical mechanical polishing composition, comprising: water; 10 to 20 wt% of colloidal silica having an average particle diameter of 100 to 150 nm; optionally a pH adjuster; optionally a biocide; a pH of greater than 10 to 12; and 0.1 to 0.5 wt% of a quaternary ammonium compound having formula (I):

1. wherein R1, R2 and R3 are each independently selected from the group consisting of: phenyl, benzyl and linear or branched C1-C5 alkyl; and X- is an anion selected from the group consisting of Br-, Cl-, I-, F- and OH-.

2. The chemical mechanical polishing composition as described in claim 1, wherein, The pH adjuster is selected from the group consisting of potassium hydroxide, sodium hydroxide, ammonium salts and mixtures thereof.

3. The chemical mechanical polishing composition as described in claim 1, wherein, The quaternary ammonium compound has the formula (I):

3. wherein R1, R2 and R3 are each independently selected from the group consisting of C1-C2 alkyl, and X- is an anion selected from the group consisting of Br-, Cl- and OH-.

4. The chemical mechanical polishing composition as claimed in claim 1, wherein, The quaternary ammonium compound having the formula (I) is selected from the group consisting of phenyltrimethylammonium chloride, phenyltrimethylammonium bromide, phenyltrimethylammonium hydroxide and mixtures thereof.

5. A method for chemically and mechanically polishing a substrate, the method comprising: providing a substrate, wherein the substrate comprises silicon oxide; providing a chemical mechanical polishing composition consisting of: water; colloidal silica abrasive; optionally one or more pH adjusters selected from sodium hydroxide, potassium hydroxide and ammonium salts; optionally a biocide; a pH greater than 7; a quaternary ammonium compound having formula (I):

5. wherein R1, R2 and R3 are each independently selected from the group consisting of phenyl, benzyl and linear or branched C1-C5 alkyl; and X- is an anion selected from the group consisting of Br-, Cl-, I-, F- and OH-; providing a chemical mechanical polishing pad having a polishing surface; producing dynamic contact at an interface between the polishing surface of the chemical mechanical polishing pad and the substrate under a down pressure of 3 to 35 kPa; and dispensing the chemical mechanical polishing composition onto the chemical mechanical polishing pad at or near the interface between the chemical mechanical polishing pad and the substrate; and wherein a portion of the silicon oxide is removed from the substrate, and the following expression is satisfied: A>A0 wherein A is the silicon oxide removal rate (in Å / min) of the chemical mechanical polishing composition, and A0 is the silicon oxide removal rate (in Å / min) of a chemical mechanical polishing composition consisting of water and colloidal silica abrasive.

6. The method as described in claim 5, wherein, The quaternary ammonium compound has the following formula (I):

6. wherein R1, R2 and R3 are each independently selected from the group consisting of C1-C2 alkyl, and X- is selected from the group consisting of Br-, Cl- and OH-.

7. The method of claim 5, wherein the following expression is satisfied: X<X0 wherein X is the defect rate of the chemical mechanical polishing composition, and X0 is the defect rate of a chemical mechanical polishing composition consisting of water and colloidal silica abrasive.

8. The method of claim 5, wherein the following expression is satisfied: (X0-X) / X0 * 100>50 wherein X is the polishing defect rate of the chemical mechanical polishing composition, and X0 is the polishing defect rate of a chemical mechanical polishing composition consisting of water and colloidal silica abrasive.

9. The method as described in claim 5, wherein, Quaternary ammonium compounds having formula (I) are selected from the group consisting of phenyltrimethylammonium chloride, phenyltrimethylammonium bromide, phenyltrimethylammonium hydroxide, and mixtures thereof.