TW202134392A - 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 liquid

The invention relates to a chemical mechanical polishing liquid.

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 damascene structure and Double metal inlaid structure. These damascene structures first cover the dielectric layer with a barrier layer, and then cover the barrier layer with metal. These metals at least need to fill the trenches to form circuit interconnections. As the device size of integrated circuits shrinks and the number of wiring layers increases, copper has better electromigration resistance and higher conductivity than aluminum. In the prior art, copper has replaced aluminum as the wire of deep submicron integrated circuits. Material. The barrier layer mainly uses tantalum or tantalum nitride to prevent copper from diffusing to adjacent dielectric layers.

In the wafer manufacturing process, chemical mechanical polishing (CMP) is used to planarize the wafer surface. These flattened wafer surfaces contribute to the multi-layer stacking of integrated circuit wafers and the development of integrated circuit technology. The copper CMP process is usually divided into two steps: the first step is to use a copper chemical mechanical polishing solution to interconnect with the metal copper and stay on the surface of the barrier layer. This step can be polished in one polishing disk or two polishing machines depending on the polishing machine. Finished on the disc; the second step is to use a chemical mechanical polishing solution for the barrier layer to remove the barrier layer, part of the dielectric layer and copper to provide a flat polishing surface. The polishing step of the barrier layer usually requires rapid removal of the barrier layer and part of the dielectric material, but in order to achieve the effect of planarizing the polished surface, the polishing solution usually needs to have different removal rates for different materials, so as to avoid causing copper as the interconnection wire. The excessive depression.

Silicon dioxide (TEOS) is a common dielectric material. With the continuous development of technology, low-k materials (BD) have been introduced in the semiconductor manufacturing process. TEOS is deposited on the surface of the BD as a capping layer. During the polishing process, the TEOS is completely removed, and the BD is partially removed. In order to increase productivity, a higher TEOS removal rate is usually required, but the removal rate of BD 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 selection ratio between the dielectric material and the copper, so as to achieve global planarization. Because TEOS has strong chemical inertness, it is difficult to increase the removal rate through chemical methods. Therefore, the current polishing liquid mainly improves the removal rate of TEOS by increasing the abrasive content of the polishing liquid, but the high content of polishing abrasive will significantly increase the BD The removal rate is not suitable to control the polishing end point.

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

Specifically, the chemical mechanical polishing liquid in the present invention contains abrasive particles, metal corrosion inhibitors, chelating agents, oxidants, non-ionic surfactants, and water.

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

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

In some embodiments, the abrasive particles are silicon dioxide.

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

In some embodiments, the metal corrosion inhibitor is an azole compound, preferably benzotriazole, tolyltriazole, 1,2,4-triazole, 5-methyl-tetrazolium One or more of azole, 5-amino-tetrazole, 5-phenyltetrazole, mercaptophenyltetrazole, benzimidazole, naphthotriazole, 2-mercapto-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 organic acids and organic amines. The organic acid is selected from oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, glycine, alanine, nitrilotriacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, amino One or more of trimethylene phosphonic acid, hydroxyethylene diphosphonic acid, ethylenediaminetetramethylene, 2-hydroxyphosphonoacetic acid, diethylenetriamine pentamethylenephosphonic 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 percentage concentration of the oxidant is 0.05-1 wt%.

In some embodiments, water is the balance.

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

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

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

Compared with the prior art, the present invention has the advantage that it can effectively adjust the removal rate of BD and copper while obtaining a high removal rate of TEOS and tantalum.

The advantages of the present invention are further illustrated by specific examples below, but the protection scope of the present invention is not limited to the following examples.

Example

According to the components and contents of Comparative Examples 1-3 and Examples 1-17 in Table 1, the other components except the oxidizing agent were mixed uniformly, with water as the balance. Then use the pH adjuster to adjust the polishing liquid to the desired pH value. Add the appropriate amount of oxidant before use and mix well.

Table 1 The composition, content and pH value of the polishing liquid of Comparative Examples 1-3 and Examples 1-17 Polishing liquid Abrasive particles Metal corrosion inhibitor Chelating agent Surfactant Oxidant 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-phenyltetrazolium 0.2 oxalic acid 0.1 hydrogen peroxide 0.8 8 (70nm) Comparative example 3 SiO2 5 Mercaptophenyl tetrazolium 0.1 Polyamino polyether methylene phosphonic acid 0.5 (Ethoxy) ₁₀ (Butoxy) ₇ C12 alcohol 0.1 hydrogen peroxide 1 7 (110nm) Example 1 SiO2 12 Benzotriazole 0.05 Ethylenediamine 0.1 (Ethoxy) ₅ (Butoxy) ₁₀ C12 alcohol 0.005 hydrogen peroxide 0.5 10 (150nm) Example 2 SiO2 12 Benzotriazole 0.05 Malonate 0.5 (Ethoxy) ₈ (Butoxy) ₁₀ C12 alcohol 0.01 hydrogen peroxide 0.5 8 (130nm) Example 3 SiO2 12 Benzotriazole 0.05 Succinic acid 0.5 (Ethoxy) ₁₅ (Butoxy) ₁₀ C11 alcohol 0.02 hydrogen peroxide 0.5 10 (150nm) Example 4 SiO2 8 Benzimidazole 0.005 Citric acid 0.5 (Ethoxy) ₂₀ (butoxy) ₁₂ C13 alcohol 0.001 hydrogen peroxide 0.3 10 (50nm) Example 5 SiO2 8 Tolyltriazole 0.01 tartaric acid 0.7 (Ethoxy) ₅ (Butoxy) ₂₀ C13 alcohol 0.002 hydrogen peroxide 0.3 11 (50nm) Example 6 SiO2 7 Tolyltriazole 0.02 Glycine 0.05 (Ethoxy) ₁₈ (Butoxy) ₁₂ C14 alcohol 0.001 hydrogen peroxide 0.05 9 (70nm) Example 7 SiO2 6 Benzotriazole 0.02 Amino Trimethylene Phosphonic Acid 1 (Ethoxy) ₈ (Butoxy) ₅ C15 alcohol 0.04 hydrogen peroxide 1 10 (70nm) 5-amino-tetrazolium 0.05 Example 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 Example 9 SiO2 5 5-amino-tetrazolium 0.03 Ethylenediaminetetraacetic acid 0.1 (Ethoxy) ₁₀ (Butoxy) ₁₄ C12 alcohol 0.05 hydrogen peroxide 0.5 10 (90nm) 1,2,4-Triazole 0.05 Example 10 SiO2 3 5-methyl-tetrazolium 0.5 Hydroxyethylene diphosphonic acid 0.7 (Ethoxy) ₈ (Butoxy) ₁₀ C12 alcohol 0.02 hydrogen peroxide 1 10 (100nm) Example 11 SiO2 12 5-phenyltetrazolium 0.2 Ethylenediaminetetramethylenephosphonic acid 0.2 (Ethoxy) ₁₂ (Butoxy) ₁₀ C12 alcohol 0.01 hydrogen peroxide 0.8 10 (200nm) Example 12 SiO2 8 5-phenyltetrazolium 0.2 2-Hydroxyphosphonoacetic acid 0.5 (Ethoxy) ₁₂ (Butoxy) ₁₈ C12 alcohol 0.05 hydrogen peroxide 0.8 12 (120nm) (110nm) Example 13 SiO2 15 Mercaptophenyl tetrazolium 0.2 Diethylene Triamine Penta (Methylene Phosphonic Acid) 0.6 (Ethoxy) ₁₂ (Butoxy) ₈ C12 alcohol 0.2 hydrogen peroxide 1 9 (20nm) Example 14 SiO2 20 Mercaptophenyl tetrazolium 0.5 Alanine 0.01 (Ethoxy) ₁₅ (butoxy) ₅ C12 alcohol 0.2 hydrogen peroxide 0.8 11 (30nm) Example 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) Example 16 SiO2 10 2-mercapto-benzothiazole 0.2 oxalic acid 0.4 (Ethoxy) ₅ (Butoxy) ₁₀ C12 alcohol 0.2 hydrogen peroxide 0.5 11 (70nm) Example 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 One

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

Table 2 The removal rate of the polishing liquid of Comparative Examples 1-3 and Examples 1-17 Polishing liquid 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 Example 1 1456 1782 2512 1172 Example 2 660 1597 1898 567 Example 3 370 1816 2477 958 Example 4 644 1049 1187 1304 Example 5 479 1330 1349 1119 Example 6 719 998 924 1321 Example 7 606 882 973 610 Example 8 358 1134 1179 1043 Example 9 550 875 932 505 Example 10 364 419 490 391 Example 11 476 1830 2252 886 Example 12 361 1511 1802 590 Example 13 302 1565 1604 298 Example 14 258 1953 2434 351 Example 15 390 1608 1745 486 Example 16 317 1320 1631 349 Example 17 813 1045 1152 559

It can be seen from Table 2 that compared with the comparative example, the polishing solution of the present invention in Examples 1-17 adds ethoxylated butoxylated alkyl alcohol as an ionic surfactant, and under alkaline conditions, the polishing solution's effect on Cu can be adjusted. The removal rate of Ta and TEOS is maintained without affecting the removal rate of Ta and TEOS. The pH of the polishing liquid of Comparative Example 3 is less than 8, which cannot achieve a high removal rate of Ta and TEOS; 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 solution of Comparative Example 1 only uses high content of abrasive particles and oxidizers, and has a high removal rate for copper (Cu), tantalum (Ta), silicon dioxide (TEOS), and low dielectric constant material BD, and The removal rate of copper (Cu) and low dielectric constant material BD cannot be effectively adjusted by the polishing liquid.

Effect embodiment two

The polishing liquid of Comparative Example 1 and the polishing liquid of Examples 1, 4, and 10 of the present invention were used to polish patterned copper wafers under the following conditions.

The graphics wafer is a commercially available 12-inch Sematech 754 graphics wafer, and the film layer material is copper/tantalum/tantalum nitride/TEOS/BD from top to bottom. The polishing process is divided into three steps. The first step uses a commercially available copper polishing solution. Most of the copper is removed, the second step uses a commercially available copper polishing solution to remove the remaining copper, and the third step uses the barrier layer polishing solution of the present invention to remove the barrier layer (tantalum/tantalum nitride), silicon dioxide TEOS, and part BD, and finally the polishing process stops on the BD layer.

The polishing conditions of the barrier layer polishing liquid are: the polishing machine is a 12” Reflexion LK machine, the polishing pad is Fujibo pad, the down pressure is 2.5 psi, the rotating speed is polishing disk/polishing head=93/87rpm, and the polishing liquid flow rate is 300ml /min, the polishing time is 60s. The measured removal rates of the polishing liquid in Comparative Example 1 and Examples 1, 4, and 10 are shown in Table 3.

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

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

It can be seen from Table 3 that although the polishing liquid of Comparative Example 1 can correct the dish-shaped depressions produced on the wafer in the future (after copper polishing), the copper area is higher than the dielectric layer area and cannot correct the dense line of the wafer. The dielectric layer generated on the area is corroded, and the crystal round appearance required by the process cannot be obtained. Compared with the polishing liquid of Comparative Example 1, the polishing liquid of the present invention can effectively control the selection ratio of TEOS/BD to the removal rate of copper, so it can better correct the future (after copper polishing) on the wafer. The dish-shaped depression and the erosion of the dielectric layer resulted in a better crystal round appearance.

In summary, the present invention provides a chemical mechanical polishing liquid that can be used for barrier layer polishing. By adding ethoxylated butoxylated alkyl alcohol as a non-ionic surfactant, the polishing liquid can be used in alkaline conditions. While obtaining high TEOS and tantalum removal rate, it can effectively adjust the removal rate of BD and copper, so as to better correct the dish-shaped depression and dielectric layer erosion produced on the wafer in the future (after copper polishing).

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

The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, all equivalent changes and modifications made without departing from the spirit and scope of the present invention should all fall within the scope of the present invention.

Claims (15)

A chemical mechanical polishing liquid includes abrasive particles, a metal corrosion inhibitor, a chelating agent, an oxidizing agent, a nonionic surfactant, and water. The nonionic surfactant is an ethoxylated butoxylated alkyl alcohol. The chemical mechanical polishing liquid according to claim 1, wherein, in the ethoxylated butoxylated alkyl alcohol, 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 or branched chain alkyl group having 11-15 carbon atoms. The chemical mechanical polishing liquid according to claim 1, wherein the mass percentage concentration of the non-ionic surfactant is 0.001-0.2 wt%. The chemical mechanical polishing liquid according to claim 3, wherein the mass percentage concentration of the non-ionic surfactant is 0.005-0.1wt%. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are silicon dioxide. The chemical mechanical polishing liquid according to claim 1, wherein the mass percentage concentration of the abrasive particles is 3-20 wt%. The chemical mechanical polishing liquid according to claim 1, wherein the metal corrosion inhibitor is an azole compound. The chemical mechanical polishing liquid according to claim 7, wherein the metal corrosion inhibitor is selected from the group consisting of benzotriazole, tolyltriazole, 1,2,4-triazole, 5-methyl -One or more of tetrazole, 5-amino-tetrazole, 5-phenyltetrazole, mercaptophenyltetrazole, benzimidazole, naphthotriazole, 2-mercapto-benzothiazole. The chemical mechanical polishing liquid according to claim 1, wherein the mass percentage concentration of the metal corrosion inhibitor is 0.005-0.5wt%. The chemical mechanical polishing liquid according to claim 1, wherein the chelating agent is selected from one or more of organic acids and organic amines. The chemical mechanical polishing liquid according to claim 10, wherein the organic acid is selected from the group consisting of oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, glycine, alanine, nitrilotriacetic acid, and 2-phosphonic acid. Butane-1,2,4-tricarboxylic acid, amino trimethylene phosphonic acid, amino trimethylene phosphonic acid, hydroxyethylene diphosphonic acid, ethylene diamine tetramethylene phosphonic acid, 2-hydroxy phosphonic acid group One or more of acetic acid, diethylenetriamine pentamethylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, and ethylenediaminetetraacetic acid; the organic amine is selected from one or more of ethylenediamine and triethanolamine Many kinds. The chemical mechanical polishing liquid according to claim 1, wherein the mass percentage concentration of the chelating agent is 0.01-2wt%. The chemical mechanical polishing liquid according to claim 1, wherein the oxidizing agent is hydrogen peroxide. The chemical mechanical polishing liquid according to claim 1, wherein the mass percentage concentration of the oxidant is 0.05-1 wt%. The chemical mechanical polishing liquid according to claim 1, wherein the pH of the chemical mechanical polishing liquid is 8-12.