CHEMICAL MECHANICAL POLISHING (CMP) COMPOSITION FOR HIGH EFFECTIVE POLISHING OF SUBSTRATES COMPRISING GERMANIUM

Abstract

Disclosed herein is a chemical mechanical polishing (CMP) composition (Q) containing (A) inorganic particles, (B) a compound of general formula (I) below, and (C) an aqueous medium, in which the composition (Q) has a pH of from 2 to 6.

##STR00001##

Claims

1: A chemical mechanical polishing (CMP) composition, (Q) comprising: (A) inorganic particles; (B) a compound of general formula (I): ##STR00004## (C) an aqueous medium, wherein: X is CH.sub.2N, CH.sub.2CH.sub.2N, CH.sub.2CH.sub.2CH.sub.2N, CH.sub.2CH.sub.2CH.sub.2CH.sub.2N, CH, CH.sub.2, CH.sub.2CH, CH.sub.2CH.sub.2CH, C═O or CH.sub.2CH.sub.2O, in which X is bonded by the carbon atom of the respective group to the nitrogen; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are independently from each other O.sup.−, H, OH, COO.sup.−, COONa, CH, CH.sub.2, CH.sub.3, CH.sub.2CH.sub.3, C.sub.1-C.sub.20-alkyl, C.sub.2-C.sub.20-alkenyl with at least one carbon carbon double bond, C.sub.1-C.sub.20-alkyl-acyl, C.sub.2-C.sub.20-alkenyl-acyl, CH.sub.2CH.sub.2OH, OHCHCHOH, CH.sub.2COO.sup.−, CH.sub.2COONa, CH.sub.2CH.sub.2O or CH.sub.2CH(CH.sub.3)O, u and t are 0 or 1; l, m, o, q, and s are an integer within a range of from 0 to 5, and n, p and r are an integer within a range of from 1 to 5 for a compound according to formula (I) having no polymeric polyether chain in the structure, l, m, o, q and s are an integer within a range of from 0 to 500 and n, p and r are an integer within a range of from 1 to 500 for a compound according to formula (I) having at least one polymeric polyether chain in the structure; and when u is at least one and X is C═O or CH.sub.2CH.sub.2O, then l or r are zero or l and r are zero, when u is one and X is CH.sub.2N, CH.sub.2CH.sub.2N, CH.sub.2CH.sub.2CH.sub.2N, CH.sub.2CH.sub.2CH.sub.2CH.sub.2N, CH, CH.sub.2, CH.sub.2CH, CH.sub.2CH.sub.2CH, then l or r are at least one or l and r are at least one, or a salt thereof, wherein the composition (Q) has a pH of from 2 to 6.

2: The CMP composition (Q) according to claim 1, wherein: X is CH.sub.2N, CH.sub.2CH.sub.2N, CH.sub.2CH.sub.2CH.sub.2N, CH.sub.2CH.sub.2CH.sub.2CH.sub.2N bonded to the nitrogen by a carbon atom of the terminal CH.sub.2; u is 1; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are independently from each other CH.sub.2CH.sub.2O or CH.sub.2CH(CH.sub.3)O forming a polyether; and t is 0, wherein the last oxyalkylene group of the polyether chain has a hydroxy function.

3: The CMP composition (Q) according to claim 2, wherein: the number of CH.sub.2CH.sub.2O groups in the polyether ranges from 1 to 300; and the number of CH.sub.2CH(CH.sub.3)O groups ranges from 1 to 500.

4: The CMP composition (Q) according to claim 1, wherein: X is CH.sub.2CH.sub.2N bonded to the nitrogen by the carbon atom of the terminal CH.sub.2; u is 1; R.sub.1, R.sub.3, R.sub.5 and R.sub.7 are CH.sub.2CH(CH.sub.3)O; m, l, n, o, p, q, r, and s are 1; t is 0; and R.sub.2, R.sub.4, R.sub.6 and R.sub.8 are hydrogen.

5: The CMP composition (Q) according to claim 1, wherein: X is CH.sub.2CH.sub.2O bonded to the nitrogen by the carbon atom of the terminal CH.sub.2 of the CH.sub.2CH.sub.2O; R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are independently from each other CH.sub.2CH.sub.2O or CH.sub.2CH(CH.sub.3)O forming a polyether; and t is 0, wherein the last oxyalkylene group of the polyether chain has a hydroxy function.

6: The CMP composition (Q) according to claim 5, wherein the number of CH.sub.2CH.sub.2O groups in the polyether ranges from 1 to 50 and the number of CH.sub.2CH(CH.sub.3)O groups is in the range of from 1 to 100.

7: The CMP composition (Q) according to claim 1, wherein: X is C═O bonded to the nitrogen by the carbon atom of the carbonyl group forming an amide; u is 1; R.sub.3 is H, CH.sub.2CH.sub.2O or CH.sub.2CH(CH.sub.3)O; R.sub.5 is CH.sub.2CH.sub.2O or CH.sub.2CH(CH.sub.3)O; R.sub.4 and R.sub.6 are H; R.sub.7 and R.sub.8 are independently from each other C.sub.1-C.sub.20-alkyl or C.sub.2-C.sub.20-alkenyl with at least one carbon carbon double bond; and t is 0 or a salt thereof.

8: The CMP composition (Q) according to claim 1, wherein (B) is characterized in that X is CH.sub.2, CH.sub.2N, CH.sub.2CH.sub.2N, CH.sub.2CH.sub.2CH.sub.2N bonded to the nitrogen by a carbon atom of the terminal CH.sub.2, u is an integer from 1 to 4 when X is CH.sub.2 otherwise 1, R.sup.1 is H, l is 1, m is 0, R.sup.3 is CH.sub.2, CH.sub.3, CH.sub.2CH.sub.2O, n is 1 when R.sup.3 is CH.sub.3 otherwise an integer from 1 to 4, R.sup.4 is OH, CH.sub.2COONa, o is 1, R.sup.5 is CH.sub.2COO.sup.−, H.sub.2COONa, p is 1, q is 0 and R.sup.7 is C.sub.8-C.sub.16-alkyl, C.sub.8-C.sub.16-acyl, r is 1, s is 0, when R.sup.7 is C.sub.8-C.sub.16-alkyl l is 0, m is 0 or a salt thereof wherein R.sup.9 is O.sup.−, CH.sub.3, CH.sub.2CH.sub.3, and t is 1.

9: The CMP composition (Q) according to claim 1, wherein (B) is characterized in that X is CH2CH, CH2CH2CH bonded to the nitrogen by the carbon atom of the terminal CH.sub.2 or X is C═O bonded to the nitrogen by the carbon atom of the carbonyl group, u is 1, R.sup.1 is C.sub.8-C.sub.16-alkyl, C.sub.8-C.sub.16-alkenyl with at least one carbon carbon double bond, l is 1, m is 0, R.sup.3 is CH.sub.2, n is an integer from 1 to 4, R.sup.4 is —OH, o is 1, R.sup.5 is CH.sub.2, CH.sub.3, p is 1 and q is 0 when R.sup.5 is CH.sub.3 or p is an integer from 1 to 4, R.sup.6 is OH, q is 1, R.sup.7 is OH, r is 1, s is 0, when X C═O r is 0 and s is 0 or a salt thereof wherein R.sup.9 is CH.sub.3, CH.sub.2CH.sub.3 and t is 1.

10: The CMP composition (Q) according to claim 1, wherein (B) is characterized in that X is CH, u is 1, R.sup.1 is CH.sub.2, l is an integer from 1 to 4, R.sup.2 is OH, m is 1, R.sup.3 is H, CH.sub.2CH.sub.2O, n is 1 when R.sup.3 is H otherwise an integer from 1 to 4, R.sup.4 is C.sub.8-C.sub.16-alkyl, C.sub.8-C.sub.16-acyl, C.sub.8-C.sub.16-alkenyl with at least one carbon carbon double bond, o is 1, R.sup.5 is H, CH.sub.2CH.sub.2O, p is 1 when R.sup.5 is H otherwise an integer from 1 to 4, R.sup.6 is C.sub.8-C.sub.16-alkyl, C.sub.8-C.sub.16-acyl, C.sub.8-C.sub.16-alkenyl with at least one carbon carbon double bond, q is 1, R.sup.7 is H, CHOH, HOCHCHOH, r is 1 and R.sup.8 is C.sub.4-C.sub.16-alkyl, s is 1 or a salt thereof, wherein R.sup.9 is CH.sub.3, t is 1 and the anion is Cl.sup.−, Br.sup.−, I.sup.− or [CH.sub.3OSO.sub.2].sup.−.

11: The CMP composition (Q) according to claim 1, wherein the inorganic particles (A) are silica.

12: The CMP composition (Q) according to claim 1, wherein the CMP composition (Q) further comprises (D) an oxidizing agent.

13: A method, comprising chemical mechanical polishing of a substrate (S) used in the semiconductor industry with the CMP composition (Q) of claim 1.

14: The method according to claim 13, wherein the substrate (S) comprises: (i) elemental germanium; or (ii) Si.sub.1-xGe.sub.x with 0.1≦x<1.

15: The method of claim 14, wherein the elemental germanium is grown in trenches between the STI (shallow-trench isolation) silicon dioxide.

16: A process for the manufacture of a semiconductor device, the process comprising chemical mechanical polishing of a substrate (S) used in the semiconductor industry in the presence of the CMP composition (Q) of claim 1.

17: The process according to claim 16, wherein the substrate (S) comprises: (i) elemental germanium; or (ii) Si.sub.1-xGe.sub.x with 0.1≦x<1.

Description

[0257] The figures show:

[0258] FIG. 1: Schematic illustration of the variation of the shape factor with the shape of a particle

[0259] FIG. 2: Schematic illustration of the variation of the sphericity with the elongation of a particle

[0260] FIG. 3: Schematic illustration of the Equivalent Circle Diameter (ECD)

[0261] FIG. 4: Energy Filtered-Transmission Electron Microscopy (EF-TEM) (120 kilo volts) image of a dried cocoon-shaped silica particle dispersion with 20 wt. % solid content on a carbon foil

EXAMPLES AND COMPARATIVE EXAMPLES

[0262] The pH value is measured with a pH electrode (Schott, blue line, pH 0-14/−5 . . . 100° C./3 mol/L sodium chloride).

[0263] Ge-cSER (cold static etching rate of a germanium layer) is determined by dipping 1×1 inch germanium coupon obtained from KAMIC Inc. into the corresponding composition for 10 minutes at 25° C. and measuring the loss of mass before and after the dipping.

[0264] Ge-hSER (hot static etching rate of a germanium layer) is determined by dipping 1×1 inch germanium coupon obtained from KAMIC Inc. into the corresponding composition for 10 minutes at 50° C. and measuring the loss of mass before and after the dipping.

[0265] Colloidal cocoon-shaped Silica particles (A1) having an average primary particle size (d1) of 35 nm and an average secondary particle size (d2) of 70 nm (as determined using dynamic light scattering techniques) (for example Fuso PL-3) were used.

TABLE-US-00016 TABLE 1 Experimental results of particle shape analysis of cocoon-shaped silica particles (A) statistical function ECD unit nm sphericity shape factor number of particles 475 475 475 average 53.67 0.631 0.881 minimum 33.68 0.150 0.513 maximum 99.78 0.997 0.978 standard deviation 11.69 0.199 0.083 median d50 51.32 0.662 0.911 d90 0.955

Procedure for Particle Shape Characterization

[0266] An aqueous cocoon-shaped silica particle dispersion with 20 wt. % solid content was dispersed on a carbon foil and was dried. The dried dispersion was analyzed by using Energy Filtered-Transmission Electron Microscopy (EF-TEM) (120 kilo volts) and Scanning Electron Microscopy secondary electron image (SEM-SE) (5 kilo volts). The EF-TEM image with a resolution of 2k, 16 Bit, 0.6851 nm/pixel (FIG. 4) was used for the analysis. The images were binary coded using the threshold after noise suppression. Afterwards the particles were manually separated. Overlying and edge particles were discriminated and not used for the analysis. ECD, shape factor and sphericity as defined before were calculated and statistically classified.

[0267] A2 are particles with a specific surface area of around 200 g/m.sup.2 with an average diameter of 15-25 nm as determined by dynamic light scattering (for example Levasil 200E supplied by Akzo Nobel). A3 are Particles with an average diameter of 85-95 nm, as determined by dynamic light scattering (for example Nexsil 125A supplied by Nyacol company).

[0268] For measuring electrophoretic mobility a standard Zetasizer Nano device from the company Malvern was used. The samples were diluted by a factor of 500 with 10 mmol/KCl solution before measuring the mobility. The measurements were carried out at 23° C.

[0269] For the evaluation on benchtop polisher, the following parameters were chosen:

[0270] Powerpro 5000 Buhler. DF=35 N, Table speed 150 rpm, Platen speed 150 rpm, slurry flow 20 ml/min, 20 s conditioning, 3 min polishing time, IC1000 pad, diamond conditioner (3M).

[0271] The pad is conditioned by several sweeps, before a new type of CMP composition is used for CMP. For the determination of removal rates at least 2 wafers are polished and the data obtained from these experiments are averaged.

[0272] The CMP composition is stirred in the local supply station.

[0273] The germanium material removal rates (Ge-MRR) for 2 inch discs polished by the CMP composition are determined by difference of weight of the coated wafers or blanket discs before and after CMP, using a Sartorius LA310 S scale. The difference of weight can be converted into the difference of film thickness since the density (5.323 g/cm.sup.3 for germanium) and the surface area of the polished material are known. Dividing the difference of film thickness by the polishing time provides the values of the material removal rate.

[0274] The silicon oxide material removal rates (oxide MRR) for 2 inch Wafers polished by the CMP composition are determined by difference of weight of the coated wafers before and after CMP, using a Sartorius LA310 S scale. The difference of weight can be converted into the difference of film thickness since the density (2.648 g/cm.sup.3 for silicon oxide) and the surface area of the polished material are known. Dividing the difference of film thickness by the polishing time provides the values of the material removal rate.

[0275] Objective to be polished: unstructured germanium wafer and/or unstructured silicon oxide wafer on bench top polisher

[0276] For wafer polishing a reflexion tool was used for 300 mm wafers and a Mirra Mesa tool was used for 200 mm wafers both supplied by AMAT. AS polishing pad, IC.sub.1000 pad (Dow chemicals) was used with platen speed of 93 rpm and Head speed of 87 rpm. Polishing pressure was 2 psi and Slurry flow was 150 mL/min for 300 mm tool and 200 mL min for Mirra Mesa polisher.

[0277] MRR was determined by weight loss using tool supplied by Metryx or by optical thickness determination of layer thickness of the Si.sub.1-xGe.sub.x layer (e.g. KLA Spectra CD100 or OP2600 tool).

[0278] The components (A), (B) and optionally (D)—each in the amounts as indicated in Table 1—were dispersed or dissolved in de-ionized water (C). pH is adjusted by adding of aqueous ammonia solution (0.1%-10%), 10% KOH solution or HNO.sub.3 (0.1%-10%) to the slurry. The pH value is measured with a pH combination electrode (Schott, blue line 22 pH).

TABLE-US-00017 TABLE 2 CMP compositions of the examples 1 to 24 and of the comparative example V1, their pH values, Ge-cSER, Ge-hSER data as well as their Ge-MRR and oxide-MRR data in the process of chemical-mechanical polishing of 2″ unstructured germanium wafers using these compositions, wherein the aqueous medium (C) of the CMP compositions is de-ionized water. The amounts of the components (A), (B), (D) are specified in weight percent (wt. %) by weight of the corresponding CMP composition. If the amounts of the components other than (C) are in total y % by weight of the CMP composition, then the amount of (C) is (100 − y) % by weight of the CMP composition. Comparative Example V1 Example 1 Example 2 Example 3 Particles (A) A1 1.5 wt. % A1 1.5 wt. % A1 1.5 wt. % A1 2.5 wt. % Oxidizing agent (D) H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 2.5 wt. % H.sub.2O.sub.2 0.75 wt. % Organic compound (B) — B1 0.1 wt % B1 0.1 wt % B1 0.1 wt % pH 4 4 4 4 Ge-MRR [Å/min] 859 820 1109 894 Ge-hSER [Å/min] 840 106 115 107 Oxide-MRR [Å/min] 177 63 69 152 Ratio Ge-MRR to 4.9 13 16 6 Oxide-MRR Example 4 Example 5 Example 6 Example 7 Particles (A) A1 1.5 wt. % A1 1.5 wt. % A1 2.5 wt. % A1 1.5 wt. % Oxidizing agent (D) H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 2.5 wt. % H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 0.75 wt. % Organic compound (B) B4 0.1 wt % B4 0.1 wt % B4 0.1 wt % B7 0.1 wt % pH 4 4 4 4 Ge-MRR [Å/min] 481 769 613 761 Ge-hSER [Å/min] 144 164 144 94 Oxide-MRR [Å/min] 9 49 84 161 Ratio Ge-MRR to 54 16 7 5 Oxide-MRR Example 8 Example 9 Example 10 Particles (A) A1 1.5 wt. % A2 1.5 wt. % A3 1.5 wt. % Oxidizing agent (D) H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 0.75 wt. % Organic compound (B) B3 B1 B7 pH 4 4 4 Ge-MRR [Å/min] 717 749 456 Ge-hSER [Å/min] 145 145 94 Oxide-MRR [Å/min] 107 9 0 Ratio Ge-MRR to 7 84 — Oxide-MRR

TABLE-US-00018 TABLE 3 Ge-Hot static etching rates [Å/min] of selected compounds (B) Ge-hSER Compound [Å/min] B4 128 B1 93 B4 144 B9 227 B3 145 B2 195 B 5 211 B7 94 B8 109 B10 34 B 15 45 B14 65 B9 228 B13 8

TABLE-US-00019 TABLE 4 CMP compositions of the examples 11 to 16, their pH values, Ge-cSER, Ge-hSER data as well as their Ge-MRR and oxide-MRR data in the process of chemical-mechanical polishing structured silicon germanium wafers using these compositions, wherein the aqueous medium (C) of the CMP compositions is de-ionized water. The amounts of the components (A), (B), (D) are specified in weight percent (wt. %) by weight of the corresponding CMP composition. If the amounts of the components other than (C) are in total y % by weight of the CMP composition, then the amount of (C) is (100 − y) % by weight of the CMP composition. Example 11 Example 12 Particles (A) A1 1.5 wt. % A1 1.5 wt. % Oxidizing agent (D) H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 0.75 wt. % Organic compound (B) B1 0.1 wt. % B1 0.1 wt. % pH 3 4 Ge-MRR [Å/min] 1214 869 Ge-hSER [Å/min] 73 94 Oxide-MRR [Å/min] 18 12 Ratio Ge-MRR to 66 72 Oxide-MRR Example 13 Example 14 Example 15 Example 16 Particles (A) A1 2.5 wt. % A1 1.5 wt. % A1 1.5 wt. % A1 2.5 wt. % Oxidizing agent (D) H.sub.2O.sub.2 0 wt. % H.sub.2O.sub.2 0.75 wt. % H.sub.2O.sub.2 2.5 wt. % H.sub.2O.sub.2 0.75 wt. % Organic compound (B) B1 0.1 wt % B1 0.1 wt % B1 0.1 wt % B1 0.1 wt % pH 4 4 4 4 Si.sub.0,6Ge.sub.0,4-MRR 379 41 35 254 [Å/min]

[0279] The CMP compositions according to the invention are showing an improved polishing performance in terms of germanium to oxide selectivity and a drastic decrease in the etching rates as can be demonstrated by the examples shown in table 2, table 3 and table 4.