Buffered slurry formulation for cobalt CMP

Described herein are polishing compositions containing an abrasive and a buffering material, wherein the pH of the polishing composition is about 6 to about 9, and methods of preparing and using the same.

BACKGROUND

The present invention relates generally to the field of polishing compositions.

SUMMARY

In one aspect, provided herein are polishing compositions comprising an abrasive and a buffering material, wherein the buffering material comprises a first component and a second component; the first component comprises a Lewis acid or a Bronsted-Lowry acid; and the second component comprises a compound devoid of a carboxylic acid moiety, with a pKa of about 6 to about 9 and wherein the difference between the pKa and the pH of the polishing composition at point of use is less than 1. In some embodiments, the abrasive comprises alumina, silica, or a combination thereof. In some embodiments, the abrasive is present in an amount of about 0.01 wt. % to about 10 wt. %. In some embodiments, the silica is precipitated silica. In some embodiments, the first component comprises acetic acid, ADA, bicine, boric acid, citric acid, 5,5-diethylbarbituric acid, EDTA, formic acid, glycine, glycylglycine, lactic acid, maleic acid, malic acid, phosphoric acid, picolinic acid, potassium hydrogen phthalate, potassium hydrogen tartrate, tricine, succinic acid, taurine, or a combination of two or more thereof. In some embodiments, the first component comprises a di- or tri-carboxylic acid. In some embodiments, the di- or tri-carboxylic acid is citric acid, malic acid, maleic acid, potassium hydrogen phthalate, potassium hydrogen tartrate, or succinic acid. In some embodiments, the first component is present in an amount of about 0.01 wt. % to about 1 wt. %. In some embodiments, the second component comprises ammonia, ACES, AMP, AMPD, AMPSO, BES, Bis-Tris, Bis-Tris-Propane, CAPSO, CHES, diethanolamine, DIPSO, EPPS, ethanolamine, N-ethylmorpholine, HEPBS, HEPES, HEPPSO, L-histidine, hydrazine, imidazole, MES, methylamine, N-methyldiethanolamine, MOBS, MOPS, MOPSO, morpholine, PIPES, piperazine, phosphate salt, POPSO, dihydrogen phosphate salt, potassium hydroxide, pyridine, hydrogen phosphate salt, TABS, TAPS, TAPSO, TEA, TES, Tris, or a combination of two or more thereof. In some embodiments, the second component comprises Tris, Bis-Tris, CHES, TAPS, TAPSO, HEPES, TES, MOPS, PIPES, or MES. In some embodiments, the second component comprises Tris, Bis-Tris, or CHES. In some embodiments, the second component is present in an amount of about 0.1 wt. % to about 4 wt. %. In some embodiments, the polishing composition further comprises a polishing accelerator. In some embodiments, the polishing accelerator is present in an amount of about 0.1 wt. % to about 10 wt. %. In some embodiments, the polishing accelerator is an amino acid. In some embodiments, the amino acid is glycine. In some embodiments, the polishing composition further comprises an oxidizer. In some embodiments, the oxidizer is present in an amount of about 0.1 wt. % to about 4 wt. %. In some embodiments, the oxidizer is hydrogen peroxide. In some embodiments, the pH of the polishing composition at point of use is about 6 to about 9. In some embodiments, the polishing composition further comprises a pH adjustor. In some embodiments, the pH adjustor is a base. In some embodiments, the base is potassium hydroxide or ammonium hydroxide. In some embodiments, the polishing composition is devoid of any corrosion inhibitor. In some embodiments, the polishing composition is devoid of any triazole-based corrosion inhibitor.

In another aspect, provided herein are polishing compositions comprising an abrasive and a buffering material, wherein the pH of the polishing composition is about 6 to about 9. In some embodiments, the abrasive comprises alumina, silica, or a combination thereof. In some embodiments, the abrasive is present in an amount of about 0.01 wt. % to about 10 wt. %. In some embodiments, the silica is precipitated silica. In some embodiments, the buffering material comprises one or more compounds selected from the group consisting of acetate salt, acetic acid, boric acid, ACES, AMP, AMPD, AMPSO, BES, bicine, Bis-Tris, Bis-Tris-Propane, borate salt, boric acid, cacodylate salt, CAPSO, CHES, citrate salt, citric acid, diethanolamine, 5,5-diethylbarbituric acid, DIPSO, EDTA, EPPS, ethanolamine, N-ethylmorpholine, formate salt, formic acid, glycine, glycylglycine, HEPBS, HEPES, HEPPSO, L-histidine, hydrazine, imidazole, lactic acid, malate salt, maleate salt, maleic acid, malic acid, MES, methylamine, N-methyldiethanolamine, MOBS, MOPS, MOPSO, morpholine, PIPES, piperazine, phosphate salt, phosphoric acid, picolinic acid, POPSO, dihydrogen phosphate salt, potassium hydrogen phthalate, potassium hydrogen tartrate, potassium hydroxide, propionate, pyridine, hydrogen phosphate salt, sodium tetraborate decahydrate, TABS, TAPS, TAPSO, TEA, TES, tetraoxalate, tricine, trimethylamine, Tris, succinate salt, succinic acid, and taurine. In some embodiments, the buffering material is present in an amount of about 0.01 wt. % to about 4 wt. %. In some embodiments, the polishing composition further comprises a polishing accelerator. In some embodiments, the polishing accelerator is present in an amount of about 0.1 wt. % to about 10 wt. %. In some embodiments, the polishing accelerator is an amino acid. In some embodiments, the amino acid is glycine. In some embodiments, the polishing composition further comprises an oxidizer. In some embodiments, the oxidizer is present in an amount of about 0.1 wt. % to about 4 wt. %. In some embodiments, the oxidizer is hydrogen peroxide. In some embodiments, the pH of the polishing composition at point of use is about 6 to about 9. In some embodiments, the polishing composition further comprises a pH adjustor. In some embodiments, the pH adjustor is a base. In some embodiments, the base is potassium hydroxide or ammonium hydroxide. In some embodiments, the polishing composition is devoid of any corrosion inhibitor. In some embodiments, the polishing composition is devoid of any triazole-based corrosion inhibitor.

In another aspect, provided herein are methods of cobalt chemical-mechanical polishing comprising applying a polishing composition disclosed herein to a substrate comprising cobalt.

In another aspect, provided herein are uses of a polishing composition disclosed herein for cobalt chemical-mechanical polishing.

In another aspect, provided herein are methods of stabilizing the cobalt removal rate in a chemical-mechanical polishing process for a substrate comprising cobalt, the method comprising applying a polishing composition disclosed herein to the substrate.

DETAILED DESCRIPTION

Provided herein, in one aspect, are polishing compositions for cobalt chemical-mechanical polishing (CMP). In some embodiments, the polishing compositions described herein exhibit more stabilized pH than previously disclosed polishing compositions. In some embodiments, the polishing compositions described herein exhibit more stabilized cobalt removal rate than previously disclosed polishing compositions. In some embodiments, the polishing compositions described herein exhibit more stabilized pH as well as more stabilized cobalt removal rate than previously disclosed polishing compositions. In further embodiments, the polishing compositions described herein exhibit better shelf life than previously reported polishing compositions.

Also provided herein, in another aspect, are polishing compositions comprising an abrasive and a buffering material, wherein the pH of the polishing composition is about 6 to about 9.

Also provided herein, in another aspect, are polishing compositions comprising an abrasive and a buffering material, wherein the buffering material comprises a first component and a second component; the first component comprises a Lewis acid or a Bronsted-Lowry acid; and the second component comprises a compound devoid of a carboxylic acid moiety, with a pKa of about 6 to about 9 and wherein the difference between the pKa and the pH of the polishing composition at point of use is less than 1. In some embodiments, the polishing composition comprises an abrasive and a buffering material, wherein the buffering material comprises malic acid and Tris. In some embodiments, the polishing composition comprises an abrasive and a buffering material, wherein the buffering material comprises malic acid and Bis-Tris. In some embodiments, the polishing composition comprises an abrasive and a buffering material, wherein the buffering material comprises malic acid and CHES. In further embodiments, the abrasive comprises precipitated silica.

Examples of abrasives include, but are not limited to alumina, silica, or combinations thereof. Silica includes precipitated silica, also typically called colloidal silica.

In some embodiments, the buffering material comprises a first component and a second component.

Illustrative first components include, but are not limited to, ADA (N-(2-acetamido)-iminodiacetic acid), acetic acid, bicine (N,N-bis(2-hydroxyethyl)glycine), boric acid, citric acid, 5,5-diethylbarbituric acid, EDTA, formic acid, glycine, glycylglycine, lactic acid, maleic acid, malic acid, phosphoric acid, picolinic acid, potassium hydrogen phthalate, potassium hydrogen tartrate, tricine (N-tris(hydroxymethyl)methylglycine), succinic acid, taurine, or a combination of two or more thereof. In some embodiments, the first component comprises a di- or tri-carboxylic acid. In further embodiments, the di- or tri-carboxylic acid is selected from the group consisting of citric acid, malic acid, maleic acid, potassium hydrogen phthalate, potassium hydrogen tartrate, succinic acid, or a combination of any two or more thereof. In some embodiments, the first component comprises malic acid.

In some embodiments, the first component comprises a Lewis acid or a Bronsted-Lowry acid, and the second component comprises a compound devoid of a carboxylic acid moiety, with a pKa of about 6 to about 9. In some embodiments, the first component comprises malic acid and the second component comprises Tris. In some embodiments, the first component comprises malic acid and the second component comprises Bis-Tris. In some embodiments, the first component comprises malic acid and the second component comprises CHES.

In some embodiments, the pH of the polishing composition at point of use is about 6 to about 9. This includes a pH of about 6 to about 8, about 6 to about 7, about 7 to about 9, about 7 to about 8, or about 8 to about 9. The pH of the polishing composition may be adjusted during preparation of the raw slurry by adding a pH adjustor. In some embodiments, the pH adjustor is a base. In still further embodiments, the base is potassium hydroxide or ammonium hydroxide. In some embodiments, the base is potassium hydroxide. In some embodiments, the base is ammonium hydroxide. In some embodiments, the pH adjustor is an acid.

In some embodiments, the polishing composition is devoid of any triazole-based corrosion inhibitor. In some embodiments, the polishing composition is devoid of any corrosion inhibitor.

Provided herein, in another aspect, are methods of cobalt chemical-mechanical polishing (CMP) comprising applying a polishing composition described herein.

Provided herein, in another aspect, are uses of a polishing composition as described herein for cobalt CMP.

Provided herein, in another aspect, are methods of stabilizing the cobalt removal rate in a CMP process for a substrate comprising cobalt, the method comprising applying a polishing composition described herein. In some embodiments, the substrate is a wafer. In further embodiments, cobalt is located on an outer layer of the wafer. In some embodiments, the polishing composition removes cobalt but does not remove silicon-containing dielectric (e.g., SiO2, SiN, SiC, SiOC, SiCN). In some embodiments, the wafer comprises one or more adhesion and/or barrier layers containing one or more of titanium nitride (TiN), tantalum nitride (TaN), Ti, and Ta, located between the cobalt layer and the interlayered dielectric (ILD). In further embodiments, one or more adhesion and/or barrier layers are left intact after the CMP process.

EXAMPLES

A glycine-based slurry A (Table 1) was examined in a pot life study in ambient air environment (FIG. 1). Slurry A was mixed with deionized water and hydrogen peroxide at day 0 (bench top polisher; 250 rpm platen rotation speed; 90 mL/min slurry flow rate; 0.68% H2O2; Fujibo H7000 pad; dilution factor: 3.3×). A pH drop as well as a cobalt removal rate increase was observed after 7 days.

The comparative slurry A was further examined under conditions with or without a nitrogen purge. The pot life study conducted under a nitrogen atmosphere exhibited minimal pH change and maintained its cobalt removal rate. Without being bound to any one particular theory, it is believed that the carbon dioxide in air dissolves in the composition and decreases the pH during the pot life.

The effect of the presence of hydrogen peroxide under ambient air conditions was also examined. Hydrogen peroxide was either added from day 0 or added immediately prior to testing (FIGS. 2 and 3). The results suggest that the presence of hydrogen peroxide from day 0 results in a pH drop and an increase in cobalt removal rate when the slurry is maintained under air.

Example 2. Study of Non-Limiting Example of Slurry with Buffering Material

Slurry A (as described in Example 1), but further comprising malic acid and Tris (pKa of 8.06 at 25° C.), was prepared (Table 1) and examined. As concentration of the buffering material increased, less change in cobalt removal rate was observed (FIG. 4). The concentration of total inorganic carbon (TIC) was also examined (FIG. 5) for this buffering material-containing slurry A and the slurries fromFIGS. 2 and 3.

Example 3. Study of Additional Non-Limiting Examples of Slurries with Buffering Material

Two slurries similar to slurry A (as described in Example 1), but further comprising malic acid and either Bis-Tris (pKa of 6.48 at 25° C.) or CHES (pKa of 9.50 at 25° C.), were prepared (Table 2) and examined. These slurries were compared with Slurry A and the slurry of Example 2. The slurries with malic acid and Tris, Bis-Tris, or CHES all maintained removal rates during a seven-day pot life study (FIG. 6), suggesting that the inclusion of buffering material is essential to avoid change in removal rate during the pot life study. Note: point of use (POU) sample included hydrogen peroxide (at POU) of 0.68 wt. % and a dilution factor of 3.3× by weight. conditions for the pot-life study: benchtop polisher, 150 rpm, 90 mL/min, 1.06 psi, Fujibo H7000 pad, coupon: 1.5 in×1.5 in.

Other embodiments are set forth in the following claims.