AQUEOUS SILICA SLURRY COMPOSITIONS FOR USE IN SHALLOW TRENCH ISOLATION AND METHODS OF USING THEM

Abstract

The present invention provides aqueous CMP polishing compositions comprising a from 0.5 to 30 wt. %, based on the total weight of the composition of a dispersion of a plurality of elongated, bent or nodular silica particles which contain a cationic nitrogen atom, and from 0.001 to 0.5 wt. %, preferably from 10 to 500 ppm, of a cationic copolymer of a diallylamine salt having a cationic amine group, such as a diallylammonium halide, or a diallylalkylamine salt having a cationic amine group, such as a diallylalkylammonium salt, or mixtures of the copolymers, wherein the compositions have a pH of from 1 to 4.5. Preferably, the cationic copolymer of a diallylamine salt having a cationic amine group comprises a copolymer of diallylammonium chloride and sulfur dioxide and the copolymer of the diallylalkylamine salt having a cationic amine group comprises a copolymer of diallylmonomethylammonium halide, e.g. chloride, and sulfur dioxide. The slurry compositions demonstrate good oxide selectivity in the CMP polishing of pattern wafers having nitride and silicon patterns.

Claims

1: An aqueous chemical mechanical planarization polishing composition comprising a dispersion of a plurality of cationic elongated colloidal silica particles which contain a cationic nitrogen atom with a dispersion of spherical colloidal silica particles, wherein colloidal silica particles have a weight average size of 25 nm to 80 nm, and from 10 to 500 ppm of a cationic copolymer of diallylammonium chloride and sulfur dioxide, a cationic copolymer of diallylmonomethylammonium chloride and sulfur dioxide, or mixtures thereof, wherein the cationic copolymers have a weight average molecular weight of 2000 to 12,000, and the compositions have a pH of 2.5 to 4 and, further wherein, the amount of the dispersion of the cationic elongated colloidal silica particles ranges from 1 to 25 wt %, all weights based on the total weight of the composition.

2: The aqueous chemical mechanical planarization polishing composition as claimed in claim 1, wherein the dispersion of the cationic elongated colloidal silica particles have for the average particle an aspect ratio of longest dimension to the diameter which is perpendicular to the longest dimension of 1.8:1 to 3:1.

3: The aqueous chemical mechanical planarization polishing composition as claimed in claim 1, comprising a mixture of a dispersion of the cationic elongated colloidal silica particles and a dispersion of spherical colloidal silica particles, wherein the amount of the dispersion of the cationic elongated colloidal silica particles ranges from 80 to 99.9 wt. %, based on the total solids weight of the colloidal silica particles in the composition.

4-10. (canceled)

11: The chemical mechanical planarization polishing composition as claimed in claim 1, wherein the cationic copolymer of diallylammonium chloride and sulfur dioxide comprises 45 to 55 mole % of the diallylammonium chloride having a cationic amine group and 45 to 55 mole % of the sulfur dioxide.

12: The chemical mechanical planarization polishing composition as claimed in claim 1, wherein the cationic copolymer of diallylmonomethylammonium chloride and sulfur dioxide comprises 45 to 55 mole % of the diallylmonomethylammonium chloride having a cationic amine group and 45 to 55 mole % of the sulfur dioxide.

13: The chemical mechanical planarization polishing composition as claimed in claim 1, wherein the amount of the cationic copolymer or mixtures thereof is from 10 to 20 ppm.

14: The chemical mechanical planarization polishing composition as claimed in claim 1, wherein the amount of the dispersion of the cationic elongated colloidal silica particles ranges from 1 to 20 wt %.

Description

EXAMPLES

[0046] The following examples illustrate the various features of the present invention.

[0047] In the Examples that follow, unless otherwise indicated, conditions of temperature and pressure are ambient or room temperature and standard pressure.

[0048] The following materials, including those listed in Table A, below, were used in the Examples that follow:

TABLE-US-00001 TABLE A Silica and Other Abrasive Particles Particle Concen- Aqueous size Raw tration Silica (CPS, Mate- (wt. % Slurry Source pH.sup.3 nm) Morphology rials solids) Slurry A HL-3.sup., 1 7.8 55 Elongated, TMOS 20 cationic.sup.2 particle Slurry B Ceria (see separate listing, below) .sup.1 Fuso Chemical, Osaka, JP; .sup.2Charge determined at pH of 3.0 and cationic particles formed with TMOS and an amine containing alkaline catalyst, such as tetramethylammonium hydroxide; .sup.3pH as delivered from source.

[0049] Copolymer 1 is a 1:1 copolymer of diallylammonium chloride and sulfur dioxide, having a weight average molecular weight (MW) (GPC using polyethylene glycol standards) of 5,000 as reported by manufacturer (PAS-92A, Nitto Boseke Co. Ltd, Fukushima, JP);

[0050] Copolymer 2 is a 1:1 copolymer of diallylmonomethylammonium chloride and sulfur dioxide, having a weight average molecular weight (MW) (GPC using polyethylene glycol standards) of 3,000 as reported by manufacturer (PAS-2201CL, Nitto Boseke Co. Ltd, Fukushima, JP);

[0051] Slurry B: Ceria slurry, pH 5.2, polyacrylic acid dispersant, 0.75 wt. % ceria solids undiluted, 1:3 dilution as used.

[0052] Slurry A is positively charged below pH 4.5.

[0053] The various silica particles used in the Examples are listed in Table A, above.

[0054] The following abbreviations were used in the Examples that follow:

[0055] POU: Point of use; RR: Removal rate;

[0056] The following test methods were used in the Examples that follow:

[0057] pH at POU:

[0058] The pH at point of use (pH at POU) was that measured during removal rate testing after dilution of the indicated concentrate compositions with water to the indicated solids content.

[0059] Removal Rate:

[0060] In a removal rate test, a Mirra (200 mm) polishing machine or Mirra RR (Applied Materials, Santa Clara, Calif.) polishing device with an IC1010 r other indicated CMP polishing pad (The Dow Chemical Company, Midland, Mich. (Dow)) was used to polish an STI pattern wafer substrate having a specified feature % (which corresponds to the area of active or high areas in the wafer relative to the total area thereof) with an MIT mask (SKW-3 wafers, SKW, Inc. Santa Clara, Calif.) using the CMP polishing compositions defined in Table 1, below, at a 20.7 kPa (3 psi) down-force, slurry flow rate of 150 mL/min, a 93 rpm platen speed and an 87 rpm carrier speed.

[0061] During polishing, the pad was conditioned with a Kinik AD3CS-211250-1FN conditioning disk (Kinik Company, Taiwan) at a 3.17 kg (7 lbf) pressure, using 100% in situ conditioning.

[0062] Multi-Step CMP PolishingP1 (First Step) and P2 (Subsequent Steps):

[0063] CMP polishing was conducted such that, in the first step or P1 process, the overburden high density plasma oxide (HDP) film was removed. The film was polished using a VP6000 polyurethane CMP polishing pad (Dow, Shore D (2 second) hardness: 53) and Slurry E and by applying a polishing down-force of 20.7 kPa (3 psi) and platen speed of 93 rpm. P1 polishing was stopped when complete planarization was achieved on the 50% pattern density (PD) feature on the middle die of the wafer. At this point, 500 of HDP film remained on the 50% feature. On the smaller features, such as the 10% and 20% PD features, however, the HDP film was completely removed and the underlying nitride film was exposed. Features with >50% PD still had significant dielectric film over the nitride film. Before moving to P2, the patterned wafer was cleaned using SP100 cleaning chemistry (TMAH containing) on a OnTrak DSS-200 Synergy tool (Lam Research, Fremont, Calif.) to remove ceria particles from the wafer. P2 polishing was performed using an IC polyurethane polishing pad (Dow, Shore D (2 second) hardness: 70) with 1010 groove design (Dow) and the indicated slurry composition, using a polishing down-force of 20.7 kPa (3 psi) and a platen speed of 93 rpm. For the 50% pattern density feature, the polishing endpoint was defined as the time at which the HDP was cleared and the nitride film was exposed. Trench oxide loss was monitored on the 50% pattern density feature for each step-polishing event. The HDP oxide removal on the 100% pattern density feature was also measured. Overpolish is defined as the amount of HDP film removed on the 100% feature after silicon nitride was exposed on the 50% pattern density feature. Selectivity was calculated as the ratio of silicon nitride removal rate to the ratio of HDP oxide removal rate on the 100% feature. All dielectric film thicknesses and removal rates were determined by measuring the film thickness before and after polishing using a KLA-Tencor FX200 metrology tool (KLA Tencor, Milpitas, Calif.) using a 49 point spiral scan with a 3 mm edge exclusion. Further polishing details are set forth in Table B, below.

TABLE-US-00002 TABLE B Polishing Parameters Pads P1: VP6000 2 mm (0.080) SIV 508 mm (20); D18AR; SG 0.8 P2: IC1010 2 mm (0.080) SIV 508 mm (20); 1010; SG 0.8 Slurry P1: ceria Slurry E (1:3) P2: Silica STI formulations Polishing 20.7 kPa (3 psi), 93/87 rpm, 150 mL/min Process Polishing Tool Applied Materials Mirra Thin Film KLA-Tencor FX200, 49 point spiral scan w/ 3 mm Metrology edge exclusion Break-in Recipe P1: 3.17 kg (7 lbf) for 40 min P2: 3.17 kg (7 lbf) for 40 min Conditioning P1: 100% in situ at 3.17 kg (7 lbf) P2: 100% in situ at 3.17 kg (7 lbf) Slurry Drop Point ~9.53 cm (~3.75) from pad center

[0064] Polishing was continued for the indicated time intervals or to the extent of the indicated overpolish amount. In each of Tables 3, 4, and 5, below, Performance Criterion A is trench oxide loss (): Acceptable trench oxide loss is less than 250 at a 500 overpolish amount, preferably, less than 215 at 500 overpolish amount; Performance Criterion B is SiN loss (): Acceptable SiN loss is less than 200 at a 500 overpolish amount, preferably, less than 150 at a 500 overpolish amount; and Performance Criterion A is dishing (): Acceptable dishing is less than 200 at 500 overpolish amount, preferably, less than 175 at 500 overpolish amount.

[0065] Where otherwise indicated, the polished substrate was a recycled tetraethoxylsilicate (TEOS) wafer (TENR) used for blanket wafer studies.

TABLE-US-00003 TABLE 1 Slurry Formulation Details Slurry/ Amount pH (wt. % Copolymer (adjusted with Slurry solids) (ppm) HNO.sub.3) 1* A/1 none 3.3 2 A/3 10 ppm of 3.3 copolymer 1 3 A/3 20 ppm of 3.3 copolymer 2 *Denotes Comparative Example.

Example: Polishing Results

[0066] Polishing was performed using the indicated slurries listed in Table 1, above, on an STI Wafer substrate having a 50% PD feature. Polishing was conducted in multiple steps using the indicated slurry. Results are shown in Table 2, below. Performance Criterion A is trench oxide loss (); Performance Criterion B is SiN loss (); and Performance Criterion A is dishing ().

TABLE-US-00004 TABLE 2 Copolymer Performance Slurry 1* 2 3 Performance Parameter A B C A B C A B C Oxide 113 52 29 23 Overpolish 218 111 54 57 Amount, 274 127 81 46 302 171 51 121 403 167 100 67 433 236 145 91 530 303 95 208 587 307 195 112 727 359 208 150 730 280 156 124 804 446 147 299 1071 609 208 401

[0067] As shown in Table 2, above, copolymer 1 provides excellent polishing performance and improves all of trench oxide loss A, SiN loss B and dishing C versus the same slurry without the copolymer in Comparative Example 1.

[0068] Compared to the composition of Comparative Example 1*, the compositions of Examples 2 and 3 show better dishing and trench oxide loss.