TWI867131B - Chemical mechanical polishing slurry - Google Patents

Abstract

The present invention provides chemical mechanical polishing slurry including abrasive particles, a metal corrosion inhibitor, a complexing agent, an oxidizer, a nonionic surfactant and water，wherein the nonionic surfactant is ethoxylated buoxygenated alkyl alcohols. The present polishing slurry has high removal rate of silicon oxide and tantalum ，tunable low-k dielectric material and copper removal rate. The present polishing slurry can meet removal rate and rate selectivity requirement of barrier CMP process.

Description

Chemical Mechanical Polishing Fluid

The present invention relates to a chemical mechanical polishing solution.

In the manufacture of integrated circuits, there are many dielectric layers containing multiple trenches on semiconductor silicon wafers. These trenches filled with metal wires are arranged in the dielectric layer to form circuit interconnection patterns. The arrangement of the patterns usually has a metal inlay structure and a double metal inlay structure. These inlay structures first use a barrier layer to cover the dielectric layer, and then use metal to cover the barrier layer. These metals need to at least fill the trenches to form circuit interconnections. As the size of integrated circuit devices decreases and the number of wiring layers increases, copper has replaced aluminum as the wiring material for deep submicron integrated circuits in existing technologies because copper has better anti-electromigration ability and high conductivity than aluminum. The blocking layer mainly uses tantalum or tantalum nitride to prevent copper from diffusing to the adjacent dielectric layer.

In the process of chip manufacturing, chemical mechanical polishing (CMP) is used to flatten the chip surface. These flattened chip surfaces contribute to the multi-layer stacking of integrated circuit chips and the development of integrated circuit technology. The copper CMP process is usually divided into two steps: the first step is to use copper chemical mechanical polishing liquid to interconnect with the metal copper and stay on the surface of the barrier layer. This step can be completed on one or two polishing disks depending on the polishing machine; the second step is to use the chemical mechanical polishing liquid of the barrier layer to remove the barrier layer, part of the dielectric layer and copper to provide a flat polished surface. The polishing step of the barrier layer usually requires the rapid removal of the barrier layer and part of the dielectric material. However, in order to achieve the effect of polishing surface flatness, the polishing liquid usually needs to have different removal rates for different materials to avoid excessive recessing of the copper used as the interconnect wire.

Silicon dioxide (TEOS) is a common dielectric material. With the continuous development of technology, low dielectric constant (Low-k) materials (BD) are introduced into the semiconductor manufacturing process. TEOS is deposited on the BD surface as a capping layer. During the polishing process, TEOS is completely removed, while BD is partially removed. In order to improve productivity, a higher TEOS removal rate is usually required, but the BD removal rate cannot be too high in order to better control the polishing process. At the same time, during the polishing process, there is a suitable polishing selectivity between dielectric materials and copper, so as to achieve global flatness. Since TEOS is chemically inert, it is difficult to increase its removal rate by chemical methods. Therefore, current polishing fluids mainly increase the abrasive content of the polishing fluid to increase the removal rate of TEOS. However, a high content of polishing abrasive will significantly increase the removal rate of BD, making it difficult to control the polishing end point.

The present invention aims to provide a chemical mechanical polishing liquid that can be used for polishing a barrier layer, which can effectively adjust the removal rates of BD and copper while obtaining high TEOS and tantalum removal rates, and can meet the requirements for wafer flatness under various process conditions.

Specifically, the chemical mechanical polishing solution of the present invention contains: abrasive particles, metal corrosion inhibitor, chelating agent, oxidizing agent, non-ionic surfactant and water.

In some embodiments, the non-ionic surfactant is an ethoxylated butoxylated alkyl alcohol, in which the number of ethoxy groups x is 5-20, the number of butoxy groups y is 5-20, and the alkyl group is a straight chain or branched chain with 11-15 carbon atoms; preferably, the alkyl group is a straight chain or branched chain with 12-14 carbon atoms.

In some embodiments, the mass percentage concentration of the non-ionic surfactant is 0.001-0.2wt%, preferably 0.005-0.1wt%.

In some embodiments, the abrasive particles are silicon dioxide.

In some embodiments, the mass percentage concentration of the abrasive particles is 3-20wt%.

In some embodiments, the metal corrosion inhibitor is an azole compound, preferably one or more of benzotriazole, toluenetriazole, 1,2,4-triazole, 5-methyltetrazolyl, 5-aminotetrazolyl, 5-phenyltetrazolyl, butylphenyltetrazolyl, benzimidazole, naphthotriazole, and 2-butyl-benzothiazole.

In some embodiments, the mass percentage concentration of the metal corrosion inhibitor is 0.005-0.5wt%, preferably 0.01-0.2wt%.

In some embodiments, the chelating agent is one or more of an organic acid or an organic amine. The organic acid is selected from one or more of oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, glycine, alanine, nitrilotriacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, aminotri(methylene)phosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylene, 2-hydroxyphosphonoacetic acid, diethylenetriaminepenta(methylene)phosphonic acid, and ethylenediaminetetraacetic acid; the organic amine is selected from one or more of ethylenediamine and triethanolamine.

In some embodiments, the mass percentage concentration of the chelating agent is 0.01-2wt%.

In some embodiments, the oxidizing agent is hydrogen peroxide.

In some embodiments, the mass percent concentration of the oxidant is 0.05-1wt%.

In some embodiments, water is the balance.

In some embodiments, the pH value of the chemical mechanical polishing solution is 8-12.

The chemical mechanical polishing solution of the present invention may also contain other additives in the art such as pH adjusters and bactericides.

The chemical mechanical polishing solution of the present invention can be prepared by concentrating the components other than the oxidant, diluting it with deionized water and adding the oxidant to the concentration range of the present invention before use.

Compared with the prior art, the advantages of the present invention are that while obtaining high TEOS and titanium removal rates, the removal rates of BD and copper can be effectively adjusted.

The advantages of the present invention are further described below through specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

Embodiment

According to the components and contents of Comparative Examples 1-3 and Examples 1-17 in Table 1, the other components except the oxidant are mixed evenly, wherein water is the balance. Then, the pH adjuster is used to adjust the polishing liquid to the desired pH value. Before use, the corresponding content of the oxidant is added and mixed evenly.

Table 1 Components, contents and pH values of the polishing solutions of Comparative Examples 1-3 and Examples 1-17 Polishing fluid Grinding particles Metal Corrosion Inhibitors Chelating agents Surfactants Oxidants pH Specific components Content wt% Specific components Content wt% Specific components Content wt% Specific components Content wt% Specific components Content wt% Comparative Example 1 SiO2 12 Benzotriazole 0.03 Citric Acid 0.1 Hydrogen peroxide 0.5 10 (150nm) Comparative Example 2 SiO2 3 5-Phenyltetrazolyl 0.2 oxalic acid 0.1 Hydrogen peroxide 0.8 8 (70nm) Comparative Example 3 SiO2 5 Benzylphenyltetrazolyl 0.1 Polyaminopolyethermethylenephosphonic acid 0.5 (Ethoxy) ₁₀ (Butoxy) ₇ C12 Alcohol 0.1 Hydrogen peroxide 1 7 (110nm) Embodiment 1 SiO2 12 Benzotriazole 0.05 Ethylenediamine 0.1 (Ethoxy) ₅ (Butoxy) ₁₀ C12 Alcohol 0.005 Hydrogen peroxide 0.5 10 (150nm) Embodiment 2 SiO2 12 Benzotriazole 0.05 Malonic acid 0.5 (Ethoxy) ₈ (Butoxy) ₁₀ C12 Alcohol 0.01 Hydrogen peroxide 0.5 8 (130nm) Embodiment 3 SiO2 12 Benzotriazole 0.05 Succinic acid 0.5 (Ethoxy) ₁₅ (Butoxy) ₁₀ C11 alcohol 0.02 Hydrogen peroxide 0.5 10 (150nm) Embodiment 4 SiO2 8 Benzimidazole 0.005 Citric Acid 0.5 (Ethoxy) ₂₀ (Butoxy) ₁₂ C13 Alcohol 0.001 Hydrogen peroxide 0.3 10 (50nm) Embodiment 5 SiO2 8 Tolyltriazole 0.01 tartaric acid 0.7 (Ethoxy) ₅ (Butoxy) ₂₀ C13 Alcohol 0.002 Hydrogen peroxide 0.3 11 (50nm) Embodiment 6 SiO2 7 Tolyltriazole 0.02 Glycine 0.05 (Ethoxy) ₁₈ (Butoxy) ₁₂ C14 Alcohol 0.001 Hydrogen peroxide 0.05 9 (70nm) Embodiment 7 SiO2 6 Benzotriazole 0.02 Aminotri(methylenephosphonic acid) 1 (Ethoxy) ₈ (Butoxy) ₅ C15 Alcohol 0.04 Hydrogen peroxide 1 10 (70nm) 5-Amino-tetrazolyl 0.05 Embodiment 8 SiO2 7 Benzotriazole 0.02 Nitrilotriacetic acid 2 (Ethoxy) ₉ (Butoxy) ₇ C13 Alcohol 0.002 Hydrogen peroxide 0.2 11 (70nm) 1,2,4-Triazole 0.05 Embodiment 9 SiO2 5 5-Amino-tetrazolyl 0.03 EDTA 0.1 (Ethoxy) ₁₀ (Butoxy) ₁₄ C12 Alcohol 0.05 Hydrogen peroxide 0.5 10 (90nm) 1,2,4-Triazole 0.05 Embodiment 10 SiO2 3 5-Methyl-tetrazolyl 0.5 Hydroxyethylidene diphosphonic acid 0.7 (Ethoxy) ₈ (Butoxy) ₁₀ C12 Alcohol 0.02 Hydrogen peroxide 1 10 (100nm) Embodiment 11 SiO2 12 5-Phenyltetrazolyl 0.2 Ethylenediaminetetramethylenephosphonic acid 0.2 (Ethoxy) ₁₂ (Butoxy) ₁₀ C12 alcohol 0.01 Hydrogen peroxide 0.8 10 (200nm) Embodiment 12 SiO2 8 5-Phenyltetrazolyl 0.2 2-Hydroxyphosphonoacetic acid 0.5 (Ethoxy) ₁₂ (Butoxy) ₁₈ C12 Alcohol 0.05 Hydrogen peroxide 0.8 12 (120nm) (110nm) Embodiment 13 SiO2 15 Benzylphenyltetrazolyl 0.2 Diethylenetriaminepenta(methylenephosphonic acid) 0.6 (Ethoxy) ₁₂ (Butoxy) ₈ C12 Alcohol 0.2 Hydrogen peroxide 1 9 (20nm) Embodiment 14 SiO2 20 Benzylphenyltetrazolyl 0.5 Alanine 0.01 (Ethoxy) ₁₅ (Butoxy) ₅ C12 Alcohol 0.2 Hydrogen peroxide 0.8 11 (30nm) Embodiment 15 SiO2 12 Naphthotriazole 0.1 2-Phosphonobutane-1,2,4-tricarboxylic acid 0.3 (Ethoxy) ₈ (Butoxy) ₁₀ C12 Alcohol 0.1 Hydrogen peroxide 0.5 11 (50nm) Embodiment 16 SiO2 10 2-Benzothiazole 0.2 oxalic acid 0.4 (Ethoxy) ₅ (Butoxy) ₁₀ C12 Alcohol 0.2 Hydrogen peroxide 0.5 11 (70nm) Embodiment 17 SiO2 6 Benzotriazole 0.03 Citric Acid 0.2 (Ethoxy) ₅ (Butoxy) ₁₀ C12 Alcohol 0.08 Hydrogen peroxide 0.5 10 (110nm) Triethanolamine 0.1

Effect Example 1

The polishing liquids of Comparative Examples 1-3 and Examples 1-17 were used to polish copper (Cu), tantalum (Ta), silicon dioxide (TEOS) and low dielectric constant material BD respectively under the following conditions. Polishing conditions: the polishing machine is a 12" Reflexion LK machine, the polishing pad is a Fujibo pad, the lower pressure is 2.5psi, the rotation speed is polishing disc/polishing head = 93/87rpm, the polishing liquid flow rate is 300ml/min, and the polishing time is 60s. The removal rates of copper (Cu), tantalum (Ta), silicon dioxide (TEOS), and low dielectric constant material BD by the polishing liquids of Comparative Examples 1-3 and Examples 1-17 were measured and recorded in Table 2.

Table 2 Removal rate of polishing solution of Comparative Examples 1-3 and Examples 1-17 Polishing fluid Cu Ta TEOS BD Removal rate (Å/min) Removal rate (Å/min) Removal rate (Å/min) Removal rate (Å/min) Comparative Example 1 680 1705 2480 2896 Comparative Example 2 103 216 257 546 Comparative Example 3 126 220 279 107 Embodiment 1 1456 1782 2512 1172 Embodiment 2 660 1597 1898 567 Embodiment 3 370 1816 2477 958 Embodiment 4 644 1049 1187 1304 Embodiment 5 479 1330 1349 1119 Embodiment 6 719 998 924 1321 Embodiment 7 606 882 973 610 Embodiment 8 358 1134 1179 1043 Embodiment 9 550 875 932 505 Embodiment 10 364 419 490 391 Embodiment 11 476 1830 2252 886 Embodiment 12 361 1511 1802 590 Embodiment 13 302 1565 1604 298 Embodiment 14 258 1953 2434 351 Embodiment 15 390 1608 1745 486 Embodiment 16 317 1320 1631 349 Embodiment 17 813 1045 1152 559

As shown in Table 2, compared with the comparative example, the polishing liquids of Examples 1-17 of the present invention can adjust the removal rate of Cu and BD by the polishing liquid under alkaline conditions by adding ethoxylated butoxylated alkyl alcohol as an ionic surfactant, while maintaining the removal rate of Ta and TEOS. The pH of the polishing liquid of Comparative Example 3 is less than 8, and a high removal rate of Ta and TEOS cannot be achieved; the pH of the polishing liquid is higher than 12, which will reduce the stability of the abrasive particles in the polishing liquid. The polishing liquid of Comparative Example 1 only uses abrasive particles and oxidants with a high content, and has a high removal rate for copper (Cu), tantalum (Ta), silicon dioxide (TEOS), and low dielectric constant material BD, and cannot effectively adjust the removal rate of the polishing liquid for copper (Cu) and low dielectric constant material BD.

Effect Example 2

The patterned copper wafer was polished using the polishing solution of Comparative Example 1 and the polishing solutions of Examples 1, 4, and 10 of the present invention under the following conditions.

The graphic wafer is a commercially available 12-inch Sematech 754 graphic wafer, and the film layer materials from top to bottom are copper/titanium/titanium nitride/TEOS/BD. The polishing process is divided into three steps. The first step is to remove most of the copper with a commercially available copper polishing solution, the second step is to remove the residual copper with a commercially available copper polishing solution, and the third step is to use the barrier layer polishing solution of the present invention to remove the barrier layer (titanium/titanium nitride), silicon dioxide TEOS, and part of the BD, and the final polishing process stops on the BD layer.

The polishing conditions of the above-mentioned barrier layer polishing liquid are as follows: the polishing machine is a 12" Reflexion LK machine, the polishing pad is a Fujibo pad, the lower pressure is 2.5 psi, the rotation speed is polishing disc/polishing head = 93/87 rpm, the polishing liquid flow rate is 300 ml/min, and the polishing time is 60 s. The removal rates of the polishing liquids of Comparative Example 1 and Examples 1, 4, and 10 are recorded in Table 3.

Table 3 Dishing and dielectric layer erosion before and after polishing with polishing liquid for Comparative Example 1 and Examples 1, 4, and 10 Polishing fluid Dish-shaped depression (Å) Dielectric Erosion (Å) Before polishing After polishing Before polishing After polishing Comparative Example 1 980 -897 174 341 Embodiment 1 950 117 177 95 Embodiment 4 951 83 166 42 Embodiment 10 948 141 173 89

The “dish-shaped depression” in Table 3 refers to the dish-shaped depression on the metal pad before the blocking layer is polished, and the “dielectric layer erosion” refers to the dielectric layer erosion on the dense line area (50% copper/50% dielectric layer) with a line width of 0.18 microns and a density of 50% on the blocking layer.

As can be seen from Table 3, although the polishing liquid of Comparative Example 1 can correct the dish-shaped depression generated on the wafer in the process (after copper polishing), the copper area is higher than the dielectric layer area, and the dielectric layer erosion generated in the dense line area of the wafer in the process cannot be corrected, and the wafer morphology required by the process cannot be obtained. Compared with the polishing liquid of Comparative Example 1, the polishing liquid of the embodiment of the present invention can effectively control the selectivity ratio of TEOS/BD to copper removal rate, so it can better correct the dish-shaped depression and dielectric layer erosion generated on the wafer in the process (after copper polishing), and obtain a better wafer morphology.

In summary, the present invention provides a chemical mechanical polishing solution that can be used for polishing a barrier layer. By adding ethoxylated butoxylated alkyl alcohol as a non-ionic surfactant, the polishing solution can effectively adjust the removal rates of BD and copper while obtaining high TEOS and tantalum removal rates under alkaline conditions, thereby better correcting the dish-shaped depressions and dielectric layer erosion generated on the wafer in the process (after copper polishing).

It should be understood that the wt% described in the present invention refers to the mass percentage.

The above detailed description of the specific embodiments of the present invention is only for example, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modification and substitution of the present invention is also within the scope of the present invention. Therefore, the equivalent changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims (13)

A chemical mechanical polishing liquid comprises abrasive particles, a metal corrosion inhibitor, a chelating agent, an oxidizing agent, a non-ionic surfactant and water, wherein the non-ionic surfactant is an ethoxylated butoxylated alkyl alcohol, wherein the number of ethoxy groups x is 5-20, the number of butoxy groups y is 5-20, and the alkyl group is a linear or branched alkyl group with 11-15 carbon atoms, and the mass percentage concentration of the non-ionic surfactant is 0.001-0.2wt%. The chemical mechanical polishing liquid as described in claim 1, wherein the mass percentage concentration of the non-ionic surfactant is 0.005-0.1wt%. The chemical mechanical polishing liquid as described in claim 1, wherein the abrasive particles are silicon dioxide. The chemical mechanical polishing liquid as described in claim 1, wherein the mass percentage concentration of the abrasive particles is 3-20wt%. The chemical mechanical polishing solution as described in claim 1, wherein the metal corrosion inhibitor is an azole compound. The chemical mechanical polishing liquid as described in claim 5, wherein the metal corrosion inhibitor is selected from one or more of benzotriazole, methylbenzotriazole, 1,2,4-triazole, 5-methyl-tetrazolyl, 5-amino-tetrazolyl, 5-phenyltetrazolyl, butylphenyltetrazolyl, benzimidazole, naphthotriazole, and 2-butyl-benzothiazole. The chemical mechanical polishing liquid as described in claim 1, wherein the mass percentage concentration of the metal corrosion inhibitor is 0.005-0.5wt%. The chemical mechanical polishing liquid as described in claim 1, wherein the chelating agent is selected from one or more of organic acids and organic amines. The chemical mechanical polishing liquid as described in claim 8, wherein the organic acid is selected from one or more of oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, glycine, alanine, nitrilotriacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, aminotrimethylenephosphonic acid, aminotrimethylenephosphonic acid, hydroxyethylenediphosphonic acid, ethylenediaminetetramethylenephosphonic acid, 2-hydroxyphosphonoacetic acid, diethylenetriaminepentamethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, and ethylenediaminetetraacetic acid; the organic amine is selected from one or more of ethylenediamine and triethanolamine. The chemical mechanical polishing liquid as described in claim 1, wherein the mass percentage concentration of the chelating agent is 0.01-2wt%. The chemical mechanical polishing solution as described in claim 1, wherein the oxidizing agent is hydrogen peroxide. The chemical mechanical polishing liquid as described in claim 1, wherein the mass percentage concentration of the oxidant is 0.05-1wt%. The chemical mechanical polishing solution as described in claim 1, wherein the pH of the chemical mechanical polishing solution is 8-12.