KR20070035572A - Cmp composition for improved oxide removal rate - Google Patents

Abstract

The present invention provides a chemical-mechanical polishing composition comprising abrasion agent, halide salt and water. The invention also provides a method for chemical-mechanical polishing of a substrate by a chemical-mechanical polishing composition and a polishing pad.

Substrates, chemical-mechanical polishing, polishing pads, abrasives, halide salts, water

Description

CMP COMPOSITION FOR IMPROVED OXIDE REMOVAL RATE

The present invention relates to polishing compositions and methods of their use in chemical-mechanical polishing of silicon dielectric layers.

A method for insulating members of a semiconductor device, comprising: forming a silicon nitride layer on a silicon substrate, forming a shallow trench through etching or photolithography, and depositing a dielectric layer to fill the trench ) The process is in the spotlight. Due to variations in the depth of trenches formed in this way, it is usually necessary to deposit excess dielectric material on top of the substrate to ensure complete filling of all trenches.

The dielectric material (eg oxide) is like the underlying form of the substrate. Thus, the surface of the substrate is characterized by the raised portion of the overlying oxide (called pattern oxide) between the trenches. The excess dielectric present outside of the trench is then typically removed by a chemical-mechanical planarization process, which also provides a flat surface for further processing. Once the pattern oxide wears off and the surface flatness is achieved, the oxide layer is hereinafter referred to as blanket oxide.

Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. The polishing composition (also known as the polishing slurry) is typically applied to the surface by contacting the surface with a polishing pad containing the abrasive material in the liquid carrier and saturated with the polishing composition. Typical abrasive materials include silicon dioxide, cerium dioxide, aluminum oxide, zirconium oxide and tin oxide. For example, US Pat. No. 5,527,423 describes a method for chemical-mechanical polishing of a metal layer by contacting a surface with an abrasive slurry comprising high purity fine metal oxide particles in an aqueous medium. The polishing composition is typically used in conjunction with a polishing pad (eg, abrasive fabric or disk). Suitable polishing pads disclose the use of solid polishing pads having surface textures or patterns, US Pat. Nos. 6,062,968, 6,117,000 and 6,126,532, which disclose the use of sintered polyurethane polishing pads having a continuous-bubble porous network. Is described in US Pat. No. 5,489,233. The abrasive material may be incorporated into the polishing pad instead of or in addition to suspending in the polishing composition. U. S. Patent No. 5,958, 794 discloses a fixed abrasive abrasive pad.

Several chemical-mechanical polishing compositions are known for low dielectric constant material containing substrates. For example, US Pat. No. 6,043,155 discloses cerium oxide-based slurries for inorganic and organic insulating films. US Pat. No. 6,046,112 discloses a polishing composition for polishing low dielectric materials, including zirconia abrasives and tetramethylammonium hydroxide or tetramethylammonium hydroxide. US Pat. No. 6,270,395 discloses polishing compositions for low dielectric materials, including abrasives and oxidants.

In the case of dielectric polishing in the STI process, the removal rate of the silicon oxide pattern can often be a speed-limiting factor, so high removal rates are desired to increase device throughput. In the polishing of pattern oxides, there is an initiation or introduction step before the rate of oxide removal becomes sufficient. Thus, a method of chemical-mechanical polishing that reduces the duration of the initiation or introduction step will reduce the time required for planarization of the substrate. However, if the blanket removal rate is too fast, over-polishing of the oxides in the exposed trenches erodes the trenches and increases device defects.

Accordingly, there is a need for improved polishing compositions and methods for planarizing silicon oxide substrates. The present invention provides such polishing compositions and methods. Further and further advantages of the invention as well as the above and other advantages of the invention will be apparent from the description of the invention provided herein.

Summary of the Invention

The invention (a) alumina, ceria, zirconia, and the wear is selected from the group consisting of a combination thereof, the 0.01% to 1% by weight, (b) Cl ^-, Br ^- anions are selected from the group consisting of ^- and I It provides a chemical-mechanical polishing composition comprising a halide salt of 0.05 mM to 30 mM and (c) water. The present invention also relates to (a) contacting the polishing pad and the chemical-mechanical polishing composition to the substrate, (b) moving the polishing pad relative to the substrate with the chemical-mechanical polishing composition between the polishing pad and the substrate, and (c) polishing the substrate by abrasion of at least a portion of the substrate.

The present invention provides a chemical-mechanical polishing composition comprising (a) abradant, (b) halide salt, and (c) water. The polishing composition preferably increases the removal rate of the pattern oxide and decreases the removal rate of the blanket oxide in the chemical-mechanical planarization of the substrate including the low dielectric layer.

As used herein, the term “component” includes any combination of components (eg, acid, base, surfactant, etc.) as well as individual components (eg, acid, base, etc.).

The abrasive is selected from the group consisting of alumina, ceria and zirconia. The abrasive is preferably alumina or ceria. More preferably, the abrasive is ceria. The amount of abrasive present in the polishing composition is preferably at least 0.01 weight percent (eg, at least 0.02 weight percent, at least 0.05 weight percent, or 0.1 weight percent based on the weight of the liquid carrier and any components dissolved or suspended therein). Above). The amount of abrasive present in the polishing composition is preferably 1% by weight or less (eg, 0.5% by weight or less) based on the weight of the liquid carrier and any components dissolved or suspended therein.

Halide salt is Cl ^- can be any of a salt having an anion selected from the group consisting of ^-, Br ^- and I. Preferably, the halide salt comprises an anion I ⁻ . The cation of the halide salt can be any suitable cation. Preferably the halide salt comprises a metal cation. Preferably, the metal cations do not exhibit chemical reactivity with any component of the substrate or polishing composition under polishing conditions. More preferably, the cation is selected from ⁺ Li, Na ^+, K ^+, Mg ^2+, Ca ^2+, Sr ^2+, Ba ²⁺ and Fe ²⁺ group consisting of. Most preferably, the halide salt is potassium iodide ("KI"). Halide salts may also be ammonium halides and pyridinium halides. The aluminum halide salt is preferably selected from the group consisting of NH ₄ Cl, NH ₄ Br and NH ₄ I, and the pyridinium halide salt is preferably C ₅ H ₅ NHCl, C ₅ H ₅ NHBr and C ₅ H ₅ NHI It is selected from the group consisting of.

The concentration of the halide salt in the polishing composition is preferably at least 0.05 mM (eg at least 0.1 mM). The concentration of the halide salt in the polishing composition is preferably at most 30 mM (eg, at most 10 mM, or at most 5 mM). The presence of halide salts in concentrations above 30 mM can delay removal of blanket oxides at unacceptably low rates. Preferred concentrations of the halide salts are by any suitable method, for example by using from 0.01% to 0.5% by weight of halide salts based on the weight of the liquid carrier and any components dissolved or suspended in the formulation of the polishing composition. Can be achieved.

The chemical-mechanical polishing composition has a pH of less than 9 (eg, 8 or less, or 7 or less). Preferably, the polishing composition has a pH of at least 3 (eg, at least 4). Even more preferably, the polishing composition has a pH of 4-7. The polishing composition optionally comprises a pH adjuster such as sodium hydroxide or hydrochloric acid. The polishing composition may optionally comprise a pH buffer system such as ammonium acetate or disodium citrate. Such pH buffer systems are well known in the art.

The chemical-mechanical polishing composition optionally comprises an organic carboxylic acid. Carboxylic acids useful in the chemical-mechanical polishing composition of the present invention include monocarboxylic and dicarboxylic acids and salts thereof. Preferably, the carboxylic acid is acetic acid, propionic acid, butyric acid, benzoic acid, formic acid, malonic acid, succinic acid, tartaric acid, lactic acid, phthalic acid, salicylic acid, anthranilic acid, citric acid, glycolic acid, fumaric acid, lauric acid, pyruvic acid, stearic acid, chloro Acetic acid, dichloroacetic acid, 2-pyridinecarboxylic acid, glycine, alanine, 3-aminopropionic acid, 4-aminobutyric acid, derivatives thereof, salts thereof, and combinations thereof. More preferably, the carboxylic acid is amino carboxylic acid.

The chemical-mechanical polishing composition may comprise any suitable amount of carboxylic acid, and typically comprises at least 0.0001% by weight of such acid. Preferably, the polishing composition comprises 0.001% to 0.5% by weight of carboxylic acid. More preferably, the polishing composition comprises 0.001% to 0.25% by weight of carboxylic acid.

It will be appreciated that the above-mentioned carboxylic acids may be present in the form of salts (eg metal salts, aluminum salts, etc.), as acids or partial salts thereof. For example, tartarate salts include tartaric acid as well as mono- and di-salts thereof. In addition, carboxylic acids comprising basic functional groups may be present in the form of acid salts of basic functional groups. For example, glycine includes glycine as well as monoacid salts thereof. In addition, some compounds may function both as acids and chelating agents (eg, certain amino acids, etc.).

Carboxylic acids perform several functions in the polishing composition. The carboxylic acid buffers the pH of the system and imparts selectivity to the oxide dielectric material on the underlying silicon nitride. The acid further improves the rate of oxide removal and the colloidal stability of the polishing composition.

The chemical-mechanical polishing composition optionally further includes one or more other additives. Such additives may include any suitable surfactant, and / or rheology control agents including viscosity enhancers and coagulants (eg, polymer rheology control agents such as urethane polymers), acrylates comprising one or more acrylic subunits. (Eg, vinyl acrylate and styrene acrylate), and polymers, copolymers and oligomers thereof, and salts thereof. Suitable surfactants include, for example, cationic surfactants, anionic surfactants, anionic polyelectrolytes, nonionic surfactants, amphoteric surfactants, fluorinated surfactants, mixtures thereof, and the like.

The chemical-mechanical polishing composition can be used to polish any substrate, and is particularly useful for polishing a substrate including one or more layers (usually substrate layers) composed of low dielectric materials. Suitable substrates include wafers used in the semiconductor industry. Wafers typically consist of, for example, metals, metal oxides, metal nitrides, metal composites, metal alloys, low dielectric materials, or combinations thereof. The method of the present invention is particularly useful for polishing substrates containing silicon dioxide.

Chemical-mechanical polishing compositions are particularly well suited for planarizing or polishing substrates that have undergone shallow trench isolation (STI) processes. The STI process typically involves providing a silicon substrate on which a silicon nitride layer is deposited. Photolithography is followed by the trench etching on the substrate consisting of the silicon nitride layer, and excess silicon dioxide is deposited thereon. Subsequently, the substrate is planarized until the silicon nitride is completely exposed so that the silicon oxide remaining in the trench is approximately the same height as the silicon nitride. Preferably, planarization or polishing is performed in such a conventional STI processing by the chemical-mechanical polishing composition of the present invention, preferably silicon dioxide is removed and the planarization is stopped in the silicon nitride layer.

Chemical-mechanical polishing compositions are particularly useful for chemical-mechanical polishing. In this regard, the present invention relates to a method comprising the steps of (a) contacting a chemical-mechanical polishing composition and a polishing pad to a substrate, (b) moving the polishing pad relative to the substrate with the chemical-mechanical polishing composition between the polishing pad and the substrate. And (c) polishing at least a portion of the substrate to polish the substrate. In conventional processes of chemical-mechanical polishing, the substrate (eg, semiconductor wafer) is pressed against the polishing pad in the presence of the polishing composition under controlled chemical, pressure, speed, and temperature conditions. The relative movement of the substrate and the pad can be circular, elliptical, or linear. Typically, the relative movement of the substrate and the pad is circular.

The substrate may be planarized or polished by the chemical-mechanical polishing composition by any suitable technique. In this regard, the polishing composition is suitably formulated prior to delivery to the surface of the polishing pad or substrate. In addition, the polishing composition may be formulated (eg, mixed) on the surface of the polishing pad or on the surface of the substrate via delivery of the polishing composition component from two or more separate sources such that the components of the polishing composition may It is appropriate to meet at the surface. In this regard, the flow rate at which the components of the polishing composition are delivered to the surface of the polishing pad or substrate (ie, the delivered amount of a particular component of the polishing composition) may vary before and / or during the polishing process such that the polishing selectivity and / or the viscosity of the polishing composition is altered. Or may be changed during the polishing process. In addition, certain components of the polishing composition delivered from two or more separate sources may have different pH values prior to delivery to the surface of the polishing pad or the surface of the substrate, or alternatively may have substantially similar or even identical pH values. It is suitable to have. In addition, certain components delivered from two or more separate sources are suitably filtered individually or jointly (eg together) prior to delivery to the surface of the polishing pad or the surface of the substrate.

The substrate may be planarized or polished by the chemical-mechanical polishing composition with any suitable polishing pad (eg, polishing surface). Suitable polishing pads include, for example, woven and nonwoven polishing pads. In addition, suitable polishing pads may include any suitable polymer that varies in density, hardness, thickness, compressibility, echo on compression, and compression coefficient. Suitable polymers include, for example, polyvinylchloride, polyvinylfluoride, nylon, fluorocarbons, polycarbonates, polyesters, polyacrylates, polyethers, polyethylenes, polyamides, polyurethanes, polystyrenes, polypropylenes, Co-formed products and mixtures thereof.

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

In the examples below, the blanket removal rate is essentially the rate of reduction (in dl / min) of the silicon dioxide layer having a continuous surface. 100% active removal rate is the rate of reduction (in dl / min) of the silicon dioxide layer that is approximately 100% accessible with the polishing pad and is synonymous with the blanket removal rate. The 50% activity removal rate is the rate of reduction (in dl / min) of the patterned silicon dioxide layer where about 50% of the surface is accessible to the polishing pad. Polishing experiments typically include in situ conditioning of a substrate with a down pressure of 27.6 kPa (4 psi), platen speed 60 rpm, carrier speed 56 rpm, polishing composition flow rate 200 mL / min and concentrically grooved CMP pads. The use of 50.8 cm (20 inch) abrasive tools included. In this embodiment, the term oxide is synonymous with silicon dioxide.

Example 1

This example demonstrates the significance of the incorporation of KI for the 100% deactivation rate and 50% deactivation rate of various abrasives. _Two polishing compositions were prepared containing 0.15 wt% ceria, 1 wt% zirconia (ZrO ₂ ), 3 wt% fumed alumina, 10 wt% fumed silica, or 10 wt% colloidal silica and water in water. One of the two compositions, respectively, also contained KI. Each polishing composition had a pH of 5. Colloidal silica was supplied as a stable aqueous suspension of silica with a range of 10 to 150 nm particle size. Similar silicon dioxide layers were polished individually with each different polishing composition. Following the use of the polishing composition, the 100% activity removal rate and 50% activity removal rate of silicon dioxide (SiO ₂ ) with each polishing composition was measured, and the result data is described in Table 1.

Composition Abrasive KI 100% active removal rate (ms / min) 50% active removal rate (ms / min) 2A (comparative) Ceria none 3924 6416 2B (invention) Ceria has exist 1917 6938 2C (comparative) ZrO ₂ none 1412 2472 2D (invention) ZrO ₂ has exist 1447 2731 2E (comparative) Fumed alumina none 247 481 2F (invention) Fumed alumina has exist 31 288 2G (comparative) Fumed silica none 116 1407 2H (comparative) Fumed silica has exist 225 1412 2I (comparative) Colloidal silica none 462 1165 2J (comparative) Colloidal silica has exist 550 1311

As is evident from the data in Table 1, the addition of KI to the ceria containing polishing composition resulted in a decrease of about 51% and a 50% increase in activity removal rate by about 8%. For zirconia containing abrasive compositions, the addition of KI increased the rate of 100% deactivation by about 2% and the rate of 50% deactivation by about 9%. For fumed alumina containing polishing compositions, the addition of KI reduced the removal rate of 100% by about 87% and the reduction of the 50% activity by about 40%. In contrast, for fumed silica containing abrasive compositions, the addition of KI reduced the removal rate of 100% by about 94% and the 50% activity removal rate by virtually no change. Similarly, the colloidal silica-containing polishing composition increased about 19% in 100% activity removal rate and 13% in 50% activity removal rate by the addition of KI.

The effect was maximal in the ceria-containing composition in which a favorable reduction was observed both at the 50% and 100% activity removal rates. In the case of zirconia-containing compositions, the 100% activity removal rate was slightly changed, but the 50% activity removal rate was increased. In the fumed alumina-containing compositions, the removal rate was reduced for both surfaces, but the ratio of 50% activity removal rate to 100% activity removal rate was advantageously changed from 2: 1 to 9: 1. Silica-containing compositions showed an unwanted increase in both the 100% activity removal rate and the 50% activity removal rate by the KI addition. Thus, the results of this example demonstrated the effect on the removal rate of two different types of surfaces, achievable by the polishing composition of the present invention.

Example 2

This example demonstrates the significance of halide anions in the polishing composition of the present invention affecting the blanket removal rate and the 50% active removal rate. Ceria and different salts in water (especially 0.5 mM KNO ₃ , 0.5 mM KCl, 0.5 mM KI, 0.25 mM K ₂ C ₂ O ₄ , 0.5 mM K ₂ C ₂ O ₄ , 2.0 mM KCl and 0.5 mM K ₂ SO ₄ ) A polishing composition containing was prepared. Similar silicon dioxide layers were polished individually with each different polishing composition. Following the use of the polishing composition, the blanket removal rate and the 50% activity removal rate were measured and the result data is described in Table 2.

Composition salt Blanket Removal Rate (Å / min) 50% active removal rate (ms / min) 3A (Control) none 4468 3655 3B (comparative) 0.5 mM KNO ₃ 2546 2942 3C (invention) 0.5 mM KI 322 5472 3D (invention) 0.5 mM KCl 1153 4193 3E (invention) 2.0 mM KCl 806 4717 3F (comparative) 0.25 mM K ₂ C ₂ O ₄ 459 329 3G (comparative) 0.5 mM K ₂ C ₂ O ₄ 208 131 3H (comparative) 0.5 mM K ₂ SO ₄ 3055 3052

As is evident from the data in Table 2, the presence of KI or KCl, compared to the control composition, decreased the blanket removal rate and increased the 50% activity removal rate. The presence of KNO ₃ or K ₂ SO ₄ reduced the removal rate of both substrates, and the presence of K ₂ C ₂ O ₄ significantly reduced the removal rate of both substrates. Thus, the results of this example demonstrate the beneficial effect of the anion present in the polishing composition and the presence of halide ions in the polishing composition of the present invention.

Claims (33)

(a) 0.01% to 1% by weight of an abrasive selected from the group consisting of alumina, ceria, zirconia and combinations thereof, (b) Cl ^-, Br ^- and I ^- halide salt 0.05 mM to about 30 mM, including anion selected from the group consisting of and (c) water Wherein the pH is less than 9; The chemical-mechanical polishing composition of claim 1 wherein the pH is 3-8. The chemical-mechanical polishing composition of claim 1 wherein the abrasive is alumina or ceria. 4. The chemical-mechanical polishing composition of claim 3, wherein the abrasive is ceria. The chemical-mechanical polishing composition of claim 4 wherein the halide salt comprises an anion I ⁻ . The method of claim 5, wherein the halide salt consisting of Li ^+, Na ^+, K ^+, Mg ^{2 +,} Ca ^{2 +,} Sr ^{2 +,} Ba ^{2 +,} Fe ^{2 +,} NH ₄ ^+, and C ₅ H ₅ NH ⁺ A chemical-mechanical polishing composition comprising a cation selected from the group. 7. The chemical-mechanical polishing composition of claim 6, wherein the halide salt is KI. 8. The chemical-mechanical polishing composition of claim 7, further comprising an organic carboxylic acid. The chemical-mechanical polishing composition of claim 1 wherein the halide salt comprises an anion I ⁻ . The method of claim 1 wherein the halide salt consisting of Li ^+, Na ^+, K ^+, Mg ^{2 +,} Ca ^{2 +,} Sr ^{2 +,} Ba ^{2 +,} Fe ^{2 +,} NH ₄ ^+, and C ₅ H ₅ NH ⁺ A chemical-mechanical polishing composition comprising a cation selected from the group. The chemical-mechanical polishing composition of claim 10, wherein the halide salt is KI. The chemical-mechanical polishing composition according to claim 1, wherein the abrasive is present in an amount from 0.01% to 0.5% by weight. The chemical-mechanical polishing composition of claim 1 wherein the halide salt is present at a concentration of 0.1 mM to 10 mM. The chemical-mechanical polishing composition of claim 1 further comprising an organic carboxylic acid. The chemical-mechanical polishing composition according to claim 14, wherein the organic carboxylic acid is selected from the group consisting of monocarboxylic acids and dicarboxylic acids. The chemical-mechanical polishing composition according to claim 15, wherein the organic carboxylic acid is amino carboxylic acid. (a) 0.01 to 1 weight percent of an abrasive selected from the group consisting of (i) alumina, ceria, zirconia and combinations thereof, (ii) Cl ^-, Br ^- and I ^- fluoride salt 0.05 mM to about 30 mM to containing an anion selected from the group consisting of, and     (iii) contacting the substrate with a polishing pad and a chemical-mechanical polishing composition comprising water and having a pH of less than 9, (b) moving the polishing pad relative to the substrate with the chemical-mechanical polishing composition between the polishing pad and the substrate, and (c) polishing the substrate by abrasion of at least a portion of the substrate Comprising, a chemical-mechanical polishing method. 18. The method of claim 17, wherein the pH of the chemical-mechanical polishing composition is 3-8. 18. The method of claim 17, wherein the abrasive is alumina or ceria. The method of claim 19, wherein the abrasive is ceria. The method of claim 20, wherein the halide salt comprises an anion I ⁻ . 22. The method of claim 21 wherein the halide salt consisting of Li ^+, Na ^+, K ^+, Mg ^{2 +,} Ca ^{2 +,} Sr ^{2 +,} Ba ^{2 +,} Fe ^{2 +,} NH ₄ ^+, and C ₅ H ₅ NH ⁺ A method comprising a cation selected from the group. The method of claim 22, wherein the halide salt is KI. The method of claim 23, further comprising an organic carboxylic acid. The method of claim 17, wherein the halide salt comprises an anion I ⁻ . 18. The method of claim 17 wherein the halide salt consisting of Li ^+, Na ^+, K ^+, Mg ^{2 +,} Ca ^{2 +,} Sr ^{2 +,} Ba ^{2 +,} Fe ^{2 +,} NH ₄ ^+, and C ₅ H ₅ NH ⁺ A method comprising a cation selected from the group. The method of claim 26, wherein the halide salt is KI. The method of claim 17, wherein the abrasive is present in an amount from 0.01% to 0.5% by weight. 18. The method of claim 17, wherein the halide salt is present at a concentration of 0.1 mM to 10 mM. 18. The method of claim 17, further comprising an organic carboxylic acid. The method of claim 30, wherein the organic carboxylic acid is selected from the group consisting of monocarboxylic acids and dicarboxylic acids. 32. The method of claim 31, wherein the organic carboxylic acid is amino carboxylic acid. The method of claim 17, wherein the substrate comprises silicon dioxide.