TWI886366B - Chemical mechanical polishing slurry and method of using the same - Google Patents

Abstract

The invention provides a chemical mechanical polishing slurry and a method of use thereof. Specifically, the chemical mechanical polishing slurry includes abrasive particle, metal corrosion inhibitor, complexing agent, oxidizer, surfactant and water, wherein the surfactant is one or more aliphatic amine derivatives. The polishing slurry in the present invention can not only meet the requirements on the removal rate and selectivity of various materials during the polishing process of the barrier layer, but also can control the topography well after polishing.

Description

Chemical mechanical polishing liquid and method of using the same

The present invention relates to the field of chemical mechanical polishing, and in particular to a chemical mechanical polishing liquid and a use method thereof.

In integrated circuit manufacturing, the standards of interconnect technology are improving. With the increase in the number of interconnect layers and the reduction in process feature size, the requirements for silicon wafer surface flatness are becoming higher and higher. Without the ability to planarize, creating complex and dense structures on semiconductor wafers is very limited. Chemical mechanical polishing (CMP) is the most effective method to achieve the flatness of the entire silicon wafer.

The CMP process uses a mixture containing an abrasive and a polishing pad to polish the surface of an integrated circuit. In a typical chemical mechanical polishing method, the substrate is directly in contact with the rotating polishing pad, and a load is used to apply pressure to the back of the substrate. During polishing, the pad and the operating table rotate while maintaining a downward force on the back of the substrate, applying an abrasive and a chemically active solution (usually called a polishing liquid or polishing slurry) to the pad, which chemically reacts with the film being polished to start the polishing process.

The CMP of the copper barrier layer is usually divided into three steps. The first step is to use a high pressure to remove a large amount of copper. The second step is to reduce the polishing pressure, remove the remaining copper on the wafer surface and stop on the barrier layer. The third step is to use a copper barrier layer polishing liquid to polish the barrier layer. In the process of removing the remaining copper in the second step, a dish-shaped depression will form on the copper surface. In response to this phenomenon, a polishing liquid with a certain removal rate selectivity ratio of copper, barrier layer material, and dielectric layer material is usually used in the third step to repair the dish-shaped depression.

As integrated circuit technology develops toward 45nm and below technology nodes and interconnection wiring density increases dramatically, the RC coupling parasitic effect caused by resistance and capacitance in the interconnection system grows rapidly, affecting the speed of the device. To reduce this effect, low-k dielectric materials must be used to reduce the parasitic capacitance between adjacent metal wires. Since the mechanical strength of low-k dielectric materials is weakened, the introduction of this material brings great challenges to process technology, especially chemical mechanical polishing (CMP) process. Generally speaking, the removal rate selectivity is adjusted by optimizing and adjusting the metal removal rate and the removal rates of the barrier layer material and the dielectric layer material. During the CMP process, the removal rate and selectivity requirements of various materials during the barrier layer polishing process must be met.

The polishing liquid provided by the present invention not only meets the requirements of the removal rate and selectivity of various materials in the process of polishing the barrier layer, but also has good repair and control capabilities for the dish-shaped depressions of different degrees after the polishing of the front copper.

In order to overcome the above technical defects, the purpose of the present invention is to provide a chemical mechanical polishing solution and a method for using the same.

Specifically, the chemical mechanical polishing solution includes: abrasive particles, metal retardant, chelating agent, oxidizing agent, surfactant, and water, wherein the surfactant is one or more fatty amine derivatives.

In some embodiments, the surfactant has the structural formula: Wherein, R ₁ is H or an organic substituent; R ₂ is H or an organic substituent; X is a nitrogen atom; and n is an integer greater than 0 and less than or equal to 80.

In some embodiments, the R ₁ is a saturated aliphatic hydrocarbon substituent having 12-18 carbon atoms; and the R ₂ is a hydrophilic substituent having an ethylene oxide structure.

In some embodiments, the mass percentage content of the surfactant is 0.0005wt%-0.1wt%.

In some embodiments, the mass percentage content of the surfactant is 0.001wt%-0.02wt%.

In some embodiments, the abrasive particles are silica particles; the mass percentage content of the abrasive particles is 2wt%-15wt%; and the particle size of the abrasive particles is 20-120nm.

In some embodiments, the metal corrosion inhibitor is one or more of benzotriazole, methylbenzotriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 2,2'-[[(methyl-1H-benzotriazole-1-yl)methyl]imino]bisethanol, carboxybenzotriazole, 4-amino-1,2,4-triazole, 5-methyl-tetrazole, 5-amino-tetrazole, 5-phenyltetrazole, butylphenyltetrazole, benzimidazole, naphthotriazole, and/or 2-butyl-benzothiazole; and the mass percentage content of the metal corrosion inhibitor is 0.001wt%-0.5wt%.

In some embodiments, the chelating agent is one or more of an organic acid and an organic amine; and the mass percentage content of the chelating agent is 0.01wt%-2.0wt%.

In some embodiments, the organic acid is one or more of oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, glycine, alanine, hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, L-cysteine, and ethylenediaminetetraacetic acid; and the organic amine compound is one or more of ethylenediamine and triethanolamine.

In some embodiments, the oxidant is hydrogen peroxide; and the mass percentage content of the oxidant is 0.05wt%-1.0wt%.

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

In addition, according to actual usage, the chemical mechanical polishing solution of the present invention may also contain other commonly used additives in this field such as a solubilizing agent and a bactericide.

The polishing liquid of the present invention can also be prepared in a concentrated form and diluted with water to the concentration range of the present invention before use.

The present invention also discloses a method for using a chemical mechanical polishing liquid, and the application of any of the above chemical mechanical polishing liquids in polishing a silicon wafer barrier layer.

Compared with the existing technology, the above technical solution has the following beneficial effects: 1. It meets the requirements of the removal rate and selectivity of various materials in the polishing process of the barrier layer; 2. It has good repair and control capabilities for dish-shaped depressions of different degrees.

The advantages of the present invention are further described below in conjunction with specific embodiments.

Table 1 shows the components and contents of the polishing liquids of Comparative Examples 1-2 and Examples 1-17. According to the formula given in the table, the components other than the oxidant are mixed evenly, and the pH value is adjusted to the required value with KOH or HNO _3. Add the oxidant before use and mix evenly. Water is the balance.

Table 1 Components and contents of the polishing liquids of Comparative Examples 1-2 and Examples 1-17 Polishing fluid Grinding particles Metal Slower Chelating agents Surfactants Oxidants pH Specific substances Content wt% Specific substances Content wt% Specific substances Content wt% Substance R1 Carbon number EO mole Content wt% Specific substances Content wt% Comparative Example 1 SiO ₂ 7 Benzotriazole 0.02 Malonic acid 0.30 - - - - _{H2O2 ​} 0.5 10 70nm Comparative Example 2 SiO ₂ 4 Benzotriazole 0.01 Citric Acid 0.10 AC1210 12 10 0.0002 _{H2O2 ​} 0.3 9 30nm Embodiment 1 SiO ₂ 6 2,2'-[[Methyl-1H-benzotriazol-1-yl]methyl]imino]bis(ethanol) 0.03 EDTA 0.25 AC1815 18 15 0.02 _{H2O2 ​} 0.8 9 50nm Embodiment 2 SiO ₂ 8 Benzylphenyltetrazolyl 0.06 Ethylenediamine 0.20 AC1215 12 15 0.04 _{H2O2 ​} 0.5 9 20nm Embodiment 3 SiO ₂ 8 Tolyltriazole 0.03 Succinic acid 0.80 AC1815 18 15 0.01 _{H2O2 ​} 0.7 8 70nm Embodiment 4 SiO ₂ 6 Benzotriazole 0.5 Citric Acid 0.05 AC1210 12 10 0.03 _{H2O2 ​} 0.8 11 50nm Embodiment 5 SiO ₂ 10 Tolyltriazole 0.05 Glycine 0.04 AC1860 18 60 0.06 _{H2O2 ​} 0.2 10 100nm Embodiment 6 SiO ₂ 6 1,2,4-Triazole 0.02 Hydroxyethylidene diphosphate 0.30 AC1230 12 30 0.08 _{H2O2 ​} 0.5 8 80nm Embodiment 7 SiO ₂ 4 3-Amino-1,2,4-triazole 0.04 Alanine 0.10 AC1850 18 50 0.1 _{H2O2 ​} 0.8 8 100nm Embodiment 8 SiO ₂ 5 Benzotriazole 0.05 Aminotrimethylenephosphonic acid 0.40 AC1830 18 30 0.1 _{H2O2 ​} 0.8 11 70nm Embodiment 9 SiO ₂ 12 5-Phenyltetrazolyl 0.01 Malonic acid 0.30 AC1210 12 10 0.03 _{H2O2 ​} 0.5 11 120nm Embodiment 10 SiO ₂ 6 Tolyltriazole 0.02 Succinic acid 2.00 AC1815 18 15 0.08 _{H2O2 ​} 0.2 10 60nm Embodiment 11 SiO ₂ 6 Carboxybenzotriazole 0.04 Diammonium Hydrogen Citrate 0.20 AC1860 18 60 0.005 _{H2O2 ​} 1.0 11 50nm Embodiment 12 SiO ₂ 4 2,2'-[[Methyl-1H-benzotriazol-1-yl]methyl]imino]bis(ethanol) 0.03 Citric Acid 0.60 AC1215 12 15 0.03 _{H2O2 ​} 0.5 10 70nm Embodiment 13 SiO ₂ 2 1,2,4-Triazole 0.001 tartaric acid 0.50 AC1830 18 30 0.06 _{H2O2 ​} 0.5 9 100nm Embodiment 14 SiO ₂ 5 3-Amino-1,2,4-triazole 0.01 Malonic acid 0.05 AC1210 12 10 0.01 _{H2O2 ​} 0.8 9 120nm Embodiment 15 SiO ₂ 8 Carboxybenzotriazole 0.02 L-Cysteine 0.40 AC1830 18 30 0.02 _{H2O2 ​} 0.05 12 80nm Embodiment 16 SiO ₂ 6 Benzotriazole 0.06 oxalic acid 0.60 AC1205 12 5 0.005 _{H2O2 ​} 0.6 8 100nm Embodiment 17 SiO ₂ 15 Carboxybenzotriazole 0.1 Glycine 0.10 AC1860 18 60 0.04 _{H2O2 ​} 0.5 8 50nm

Copper (Cu), tantalum (Ta), silicon dioxide (TEOS), and low dielectric material (BD) as well as commercially available graphic wafer Sematec754 were polished under the following conditions using the polishing liquids in Comparative Examples 1-2 and Examples 1-17. A large amount of copper was removed from the graphic wafer using commercially available copper polishing liquid, and the wafer stopped on the barrier layer, and then polished using the above-mentioned barrier layer polishing liquid. Polishing conditions: The polishing machine is a 12” Reflexion LK machine, the polishing pad is a soft polishing pad manufactured by Fujibo Co., Ltd., the downward pressure is 1.5 psi, the rotation speed is polishing disc/polishing head = 83/77 rpm, the polishing liquid flow rate is 300 ml/min, and the polishing time is 1 min. The test results are recorded in Table 2.

Table 2 Removal rates of copper (Cu), tantalum (Ta), silicon dioxide (TEOS) and low dielectric material (BD) by the polishing solutions of Comparative Examples 1-2 and Examples 1-17, as well as dishing test data before and after polishing Polishing fluid Removal rate (Å/min) Dish-shaped depression (Å) Cu Ta TEOS BD Before polishing After polishing Comparative Example 1 500 540 510 1500 350 -99 Comparative Example 2 320 350 330 820 280 170 Embodiment 1 340 490 480 180 280 51 Embodiment 2 500 630 700 220 300 91 Embodiment 3 480 550 580 350 330 56 Embodiment 4 100 530 520 120 330 -50 Embodiment 5 380 800 890 85 280 120 Embodiment 6 510 490 430 65 280 121 Embodiment 7 370 350 400 50 280 100 Embodiment 8 230 470 480 40 280 131 Embodiment 9 210 900 960 240 330 -20 Embodiment 10 270 530 510 110 280 78 Embodiment 11 250 500 510 500 350 -10 Embodiment 12 120 360 410 230 350 -31 Embodiment 13 350 310 280 100 280 106 Embodiment 14 410 450 480 370 310 -3 Embodiment 15 130 510 600 155 350 -28 Embodiment 16 550 280 220 410 310 -39 Embodiment 17 560 700 720 70 280 140

The dish-shaped depression mentioned above refers to the dish-shaped depression on the metal pad before and after the blocking layer is polished. A positive value means that the dielectric layer on both sides of the copper wire is higher than the copper wire, and a negative value means that the copper wire is higher than the dielectric layer on both sides. Too large or too small dish-shaped depression will have an adverse effect on subsequent processes.

As shown in Table 2, compared with the comparative polishing liquid 1 without the above-mentioned surfactant, and the comparative polishing liquid 2 with the addition of a low concentration of surfactant, under the condition of having the same or even lower polishing rate selectivity, the polishing liquids 1-17 all showed a more effective repairing ability for the dishing pits produced after copper polishing. At the same time, the copper removal rate can still be maintained at a relatively high level.

It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technical personnel familiar with the field may use the technical contents disclosed above to change or modify them into equivalent effective embodiments. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the contents of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims (11)

A chemical mechanical polishing liquid is characterized in that it comprises: abrasive particles, a metal retardant, a chelating agent, an oxidizing agent, a surfactant, and water, wherein the surfactant is one or more fatty amine derivatives, wherein the structural formula of the surfactant is: wherein R ₁ is H or an organic substituent; R ₂ is H or an organic substituent; X is a nitrogen atom; and n is an integer greater than 0 and less than or equal to 80. The chemical mechanical polishing liquid as described in claim 1, wherein _R1 is a saturated aliphatic hydrocarbon substituent having 12 to 18 carbon atoms; and _R2 is a hydrophilic substituent having an ethylene oxide structure. The chemical mechanical polishing liquid as described in claim 1, wherein the mass percentage content of the surfactant is 0.0005wt%-0.1wt%. The chemical mechanical polishing liquid as described in claim 3, wherein the mass percentage content of the surfactant is 0.001wt%-0.02wt%. The chemical mechanical polishing liquid as described in claim 1, wherein the abrasive particles are silica particles; the mass percentage content of the abrasive particles is 2wt%-15wt%; and the particle size of the abrasive particles is 20-120nm. The chemical mechanical polishing liquid as described in claim 1, wherein the metal corrosion inhibitor is one or more of benzotriazole, methylbenzotriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 2,2'-[[(methyl-1H-benzotriazole-1-yl)methyl]imino]diethanol, carboxybenzotriazole, 4-amino-1,2,4-triazole, 5-methyl-tetrazole, 5-amino-tetrazole, 5-phenyltetrazole, butylphenyltetrazole, benzimidazole, naphthotriazole, and/or 2-butyl-benzothiazole; and the mass percentage content of the metal corrosion inhibitor is 0.001wt%-0.5wt%. The chemical mechanical polishing liquid as described in claim 1, wherein the chelating agent is one or more of an organic acid and an organic amine; and the mass percentage content of the chelating agent is 0.01wt%-2.0wt%. The chemical mechanical polishing liquid as described in claim 7, wherein the organic acid is one or more of oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, glycine, alanine, hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, L-cysteine, and ethylenediaminetetraacetic acid; and the organic amine compound is one or more of ethylenediamine and triethanolamine. The chemical mechanical polishing liquid as described in claim 1, wherein the oxidant is hydrogen peroxide; and the mass percentage content of the oxidant is 0.05wt%-1.0wt%. The chemical mechanical polishing solution as described in claim 1, wherein the pH value of the chemical mechanical polishing solution is 8-12. A method for using a chemical mechanical polishing solution is characterized in that the chemical mechanical polishing solution as described in any one of claims 1 to 10 is used in polishing a silicon wafer barrier layer.