Composite abrasive particle with core-shell structure, chemical mechanical polishing solution for copper barrier layer and application of chemical mechanical polishing solution

Abstract

The invention provides a composite abrasive particle with a core-shell structure, a chemical mechanical polishing solution for a copper barrier layer and application of the chemical mechanical polishing solution, the polishing solution is prepared from the following components in percentage by mass: 2-15% of abrasive particles, 0.001-0.1% of an inhibitor, 0.001-0.5% of a complexing agent and 0.01-1.5% of a surfactant, the abrasive particles comprise silicon dioxide and the composite abrasive particle with the core-shell structure, the use amount of the composite abrasive particles is 0-10% of the total mass of the abrasive particles; the particle size of the silicon dioxide is 20-100 nm, and the particle size distribution index of the silicon dioxide is 0.1-0.5; the viscosity of the chemical mechanical polishing solution is 0.5 mpa.s to 2.5 mpa.s, and the pH value of the chemical mechanical polishing solution is 8.0 to 12.0. The polishing solution provided by the invention has high barrier layer material and dielectric layer material removal rate and adjustable low dielectric material and copper removal rate under relatively mild conditions, and can well control the generation of dishing and dielectric layer erosion in the polishing process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical mechanical polishing (CMP), and in particular to a core-shell structured composite abrasive, a copper barrier layer chemical mechanical polishing liquid and application thereof. BACKGROUND

[0002] At present, in the manufacture of integrated circuits, with the continuous improvement of the standard of interconnection technology, the continuous increase of the number of interconnection layers and the continuous reduction of the process feature size, the requirement for the flatness of the silicon wafer surface is also higher and higher. If planarization cannot be achieved, it will be very limited to create complex and dense structures on the semiconductor wafer.

[0003] At present, the chemical mechanical polishing method (CMP) is the most effective method that can achieve the planarization of the entire silicon wafer. The CMP process is to polish the surface of an integrated circuit using a mixture containing abrasive and a polishing pad. In a typical chemical mechanical polishing method, the substrate is directly contacted with a rotating polishing pad, and a load is applied to the back of the substrate. During polishing, the pad and the operating table rotate while maintaining the downward force on the back of the substrate, and abrasive and chemically active solution (commonly known as polishing liquid or polishing slurry) is applied to the pad, which reacts with the film being polished to start the polishing process.

[0004] With the development of integrated circuit technology towards ultra-deep submicron (32, 28nm), the parasitic capacitance caused by the reduction of feature size increasingly affects the performance of the circuit. In order to reduce this effect, low dielectric materials must be used to reduce the parasitic capacitance between adjacent metal lines. Currently, the low dielectric material commonly used is BD (Black Diamond). In the CMP process, in addition to strictly controlling the surface contaminant index and eliminating metal corrosion, it is also necessary to have lower dishing and polishing uniformity to ensure more reliable electrical performance. In particular, in the planarization process of the barrier layer, it is necessary to quickly remove the barrier layer metal and the dielectric layer oxide under lower pressure and in a shorter time, and to stop well on the surface of the low dielectric material to form an interconnection line, and it is not sensitive to small size patterns. This poses a higher challenge to CMP. Because the low dielectric material is usually carbon-doped silicon dioxide, to control the residual thickness of the stop layer, it is necessary to have strong control ability of the selectivity ratio, and also to have high stability and easy cleaning characteristics.

[0005] At present, there are many chemical mechanical polishing liquids for barrier layer planarization in the market, such as CN1400266 discloses a kind of alkaline barrier layer polishing liquid, which contains silica abrasive, amine compound and non-ionic surfactant, which will cause corrosion to copper metal layer after polishing; CN101372089A discloses a kind of alkaline barrier layer polishing liquid, which contains silica abrasive, corrosion inhibitor, oxidizing agent, non-ionic fluorine surfactant, aromatic sulfonic acid oxidizing agent compound, which has low barrier layer polishing rate and low polishing efficiency; CN101012356A discloses a kind of acidic barrier layer polishing liquid, which contains oxidizing agent, partially covered with aluminum silica particles, inhibitor and complexing agent, which has serious corrosion to copper metal layer.

[0006] Therefore, in view of the problems in the prior art, it is urgent to find a kind of chemical mechanical polishing liquid which can be suitable for barrier layer polishing in copper interconnection process, and can realize high removal rate of barrier layer and dielectric material under relatively mild conditions, while well controlling Dishing and Erosion. SUMMARY

[0007] To solve the above problems, the present application provides a kind of barrier layer chemical mechanical polishing liquid, which has high removal rate of barrier layer material and dielectric layer material under relatively mild conditions, and adjustable low removal rate of dielectric layer material and copper, and can well control the occurrence of Dishing and Erosion in the polishing process.

[0008] Specifically, the present application provides a kind of copper barrier layer chemical mechanical polishing liquid, which comprises the following components in mass percentage: 2-15% of abrasive particles, 0.001-0.1% of inhibitor, 0.001-0.5% of complexing agent and 0.01-1.5% of surfactant, wherein the abrasive particles contain silica and composite abrasive particles with core-shell structure, the amount of the composite abrasive particles is 0-10% of the total mass of the abrasive particles; the particle size of the silica is 20-100 nm, and the particle size distribution index of the silica is 0.1-0.5; the viscosity of the chemical mechanical polishing liquid is 0.5-2.5 mpa.s, and the pH value of the chemical mechanical polishing liquid is 8.0-12.0.

[0009] The composite abrasive particles with core-shell structure contain alumina core and shell layer formed on the surface of the alumina core, and the shell layer contains silicone resin or polyethylene glycol ester.

[0010] The particle size of the silica is 20-80 nm, and further preferably 20-50 nm.

[0011] The particle size distribution index of the silica is 0.1-0.3.

[0012] The viscosity of the chemical mechanical polishing fluid is 0.8-2.0 mPa·s.

[0013] The mass ratio of the complexing agent to the inhibitor is 7:1 to 1:1, preferably 3:1 to 1.5:1.

[0014] The polishing solution contains hydrogen peroxide and / or potassium persulfate.

[0015] The polishing solution contains hydrogen peroxide and potassium persulfate, wherein the mass ratio of hydrogen peroxide to potassium persulfate is 4:1 to 1:1.

[0016] The mass percentage of the core-shell structured composite abrasive particles in the grinding particles is 0.01-8%, more preferably 0.1-6%.

[0017] The complexing agent is selected from one or more of malonic acid, succinic acid, malic acid, citric acid, maleic acid, ethylenediaminetetraacetic acid, aminotrimethylphosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylphosphonic acid, pyridine-2,3-dicarboxylic acid, pyridine dicarboxylic acid, glycine, and glutamic acid diacetic acid.

[0018] The inhibitor is selected from one or more of benzotriazole, 1,2,4-triazole, 5-aminotetrazole, 1,2-benzisothiazolin-3-one, mercaptobenzothiazole, hydroxybenzotriazole, and methylbenzotriazole.

[0019] Compared with the prior art, the technical advantages of the present invention are as follows:

[0020] 1) The barrier layer chemical mechanical polishing slurry of the present invention has a high removal rate of barrier layer material and dielectric layer material and an adjustable removal rate of low dielectric material and copper under relatively mild conditions.

[0021] 2) The barrier layer chemical mechanical polishing slurry of the present invention can effectively control the occurrence of dishing and erosion during the polishing process. Detailed Implementation

[0022] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0023] A core-shell structured composite abrasive grain includes an alumina core and a shell formed on the surface of the alumina core, the shell comprising a silicone resin or polyethylene glycol ester.

[0024] In embodiments of the present invention, the alumina is selected from α-Al2O3.

[0025] A chemical mechanical polishing (CMP) slurry for copper barrier layers comprises the following components by mass percentage: 2-15% abrasive particles, 0.001-0.1% inhibitor, 0.001-0.5% complexing agent, and 0.01-1.5% surfactant, with the balance being water. The CMP slurry has a viscosity of 0.5-2.5 mPa·s and a pH value of 8.0-12.0.

[0026] In embodiments of the present invention, the concentration of the grinding particles by mass percentage is 2% to 15%, for example 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, preferably 3% to 12%.

[0027] In embodiments of the present invention, the grinding particles are selected from silica nanoparticles, the particle size of the silica nanoparticles is 20-100nm, for example including but not limited to 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, preferably 20-80nm; the particle size distribution index of the silica nanoparticles is 0.1-0.5, for example including but not limited to 0.1, 0.2, 0.3, 0.4 or 0.5, preferably 0.1-0.3.

[0028] In at least one embodiment of the present invention, the abrasive particles may further comprise core-shell structured composite abrasive particles, wherein the mass percentage of the core-shell structured composite abrasive particles in the abrasive particles is 0% to 10%, more preferably 0.01-8%, and even more preferably 0.1-6%. The use of silicone resin or polyethylene glycol ester as a soft shell layer can reduce pitting and corrosion after polishing.

[0029] The inhibitor is selected from one or more of benzotriazole, 1,2,4-triazole, 5-aminotetrazole, 1,2-benzisothiazolin-3-one, mercaptobenzothiazole, hydroxybenzotriazole, and methylbenzotriazole; the concentration of the inhibitor by mass percentage is 0.001%-0.1%, for example, 0.001%, 0.005%, 0.01%, 0.05%, or 0.1%.

[0030] The complexing agent is selected from one or more of acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, malic acid, citric acid, maleic acid, ethylenediaminetetraacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, aminotrimethylphosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylphosphonic acid, glycine, pyridine-2,3-dicarboxylic acid, pyridine dicarboxylic acid, glutamic acid diacetic acid, and ethylenediamine. The concentration of the complexing agent by mass percentage is 0.001-0.5%, for example, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0031] In embodiments of the present invention, the mass ratio of the complexing agent to the inhibitor is 7:1 to 1:1, for example, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1.5:1 or 1:1, preferably 3:1 to 1.5:1. Within this range, a balance can be achieved between polishing rate, selectivity, and copper surface quality (anti-denting / corrosion).

[0032] The surfactant is selected from one or more of polyethylene glycol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol, polyether-modified siloxane, polyvinylpyrrolidone, Dynol surfactant, Surflynol surfactant, and Triton, preferably polyvinylpyrrolidone or a mixture of polyethylene glycol and polyether-modified siloxane; the concentration of the surfactant by mass percentage is 0.01-1.5%, for example: 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%.

[0033] The oxidant in the polishing solution is selected from one or more of hydrogen peroxide, peracetic acid, potassium persulfate, and ammonium persulfate, and the mass percentage concentration of the oxidant is 0.05-2.0%. In at least one embodiment of the present invention, the oxidant comprises hydrogen peroxide and potassium persulfate, wherein the mass ratio of hydrogen peroxide to potassium persulfate is 4:1-1:1.

[0034] The pH adjuster is selected from inorganic or organic bases such as H3PO4, HNO3, potassium hydroxide, and potassium carbonate, and the pH range of the adjusted copper barrier layer polishing solution is 8 to 12.

[0035] In the polishing solution of the present invention, in addition to the above-mentioned components, the remainder is water.

[0036] In this embodiment of the invention, the viscosity of the chemical mechanical polishing fluid is 0.5-2.5 mPa·s.

[0037] The chemical mechanical polishing fluid of the present invention can be prepared by the following method: mixing all components except the oxidant in proportion, adjusting the pH value to the required value with a pH adjuster, adding the oxidant before use, and mixing evenly.

[0038] The advantages of the present invention are further illustrated below with more specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0039] Synthesis example 1

[0040] Synthesis of α-Al₂O₃ cores coated with organosilicon resin

[0041] (1) Disperse α-Al2O3 particles (30nm) in anhydrous ethanol, sonicate them to form a suspension with a mass concentration of 8%; add 3-aminopropyltriethoxysilane (6% of the mass of α-Al2O3), adjust the pH to 5 (using dilute hydrochloric acid), and stir at 60°C for 2 hours.

[0042] (2) Methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) were mixed at a mass ratio of 7:3 (the total amount of monomers was 25% of the mass of α-Al2O3); the mixed monomers were slowly added dropwise to the above α-Al2O3 suspension and stirred at 60°C for 5 hours; during this period, the pH was adjusted to 8-9 with ammonia water to promote the hydrolysis and condensation of the monomers;

[0043] (3) After the reaction is complete, centrifuge, wash and dry; then bake at 120℃ for 1 hour to obtain organosilicon resin coated α-Al2O3.

[0044] Table 1 shows the formulations of polishing solutions 1-24 of the present invention and comparative polishing solutions 1-3. According to the formulations given in the table, all components except the oxidant are mixed evenly, and the pH value is adjusted to the required value using KOH or HNO3. The oxidant is added before use, and the mixture is thoroughly mixed. Water is the balance. The particle size distribution index (PDI) of the silica abrasive particles is measured by dynamic light scattering (DLS). The viscosity of the polishing solution is measured by rotational viscometer method. The test temperature is 25±0.2℃, the viscometer model is Brookfield DV2T, the rotor is UL(0), and the rotor speed is 100RPM. After running at the set speed for 3 minutes, the reading is recorded. The same sample is measured twice in parallel. The absolute difference between the two data is ≤0.2 mPa·s. The arithmetic mean of the two test data is taken as the final viscosity value of the polishing solution.

[0045] Table 1 Polishing solutions 1-24 of the present invention and comparative polishing solutions 1-3

[0046]

[0047] Example 1

[0048] Copper (Cu), tantalum (Ta) barrier layer material, silicon dioxide (TEOS) dielectric material, and low dielectric (BD) material were polished using polishing slurries 1-24 of the present invention and comparative polishing slurries 1-3 under the following conditions. Polishing conditions: 12” Reflexion LK polishing machine, Fujibo pad, downforce 1.5 psi, rotation speed of polishing disc / polishing head = 113 / 107 rpm, polishing slurry flow rate 300 ml / min, and polishing time 1 min.

[0049] Table 2 shows the removal rates of copper (Cu), tantalum (Ta), silicon dioxide (TEOS), and low-dielectric materials (BD) by polishing solutions 1-24 of the present invention and comparative polishing solutions 1-3.

[0050]

[0051] As shown in Table 2, compared with the comparative polishing solutions 1, 2 and 3, the polishing solution of the present invention can achieve a higher removal rate of the barrier layer material Ta and the dielectric layer material silicon dioxide (TEOS), which can shorten the polishing time and increase the production capacity.

[0052] Example 2

[0053] Patterned copper wafers were polished using polishing slurries 1-24 of the present invention and comparative polishing slurries 1-3 under the following conditions. The patterned chip was a commercially available 12-inch Sematech 754 patterned chip, with the film material from top to bottom being copper / tantalum / tantalum nitride / TEOS / BD. The polishing process consisted of three steps: first, most of the copper was removed using commercially available copper polishing slurry; second, residual copper was removed using commercially available copper polishing slurry; and third, the barrier layer polishing slurry of the present invention was used to remove the barrier layer (tantalum / tantalum nitride), silicon dioxide (TEOS), and part of the low-dielectric material (BD), and the material was left on the BD layer. The barrier layer polishing conditions were as follows: a 12” Reflexion LK polishing machine, a Fujibo pad, a downforce of 1.5 psi, a rotation speed of polishing disc / polishing head = 113 / 107 rpm, a polishing slurry flow rate of 300 ml / min, and a polishing time of 70 s.

[0054] Table 3 Comparison of the corrective ability of polishing slurries 1-24 of the present invention and comparative polishing slurries 1-3 on patterned copper wafers after polishing.

[0055]

[0056] In this context, Dishing refers to the dish-shaped depression on the metal pad before the barrier layer is polished; Erosion refers to the erosion of the dielectric layer on a densely packed area (50% copper / 50% dielectric layer) with a line width of 0.18 micrometers and a density of 50%; and Δ (angstrom) refers to the correction capability value after polishing.

[0057] As can be seen from Table 3, compared with the comparative polishing slurries 1-3, the polishing slurry of the present invention can stop on the BD well because it inhibits the removal rate of the low dielectric material BD, effectively controls the polishing process of the pattern chip and ensures the remaining thickness of the BD after polishing. It can better correct the dish-shaped depressions and dielectric layer erosion generated on the wafer in the previous process (after copper polishing) and obtain a better wafer morphology.

[0058] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A core-shell structured composite abrasive, characterized in that, It includes an alumina core and a shell formed on the surface of the alumina core, the shell comprising a silicone resin or a polyethylene glycol ester.

2. A chemical mechanical polishing slurry for a copper barrier layer, characterized in that, The slurry comprises, by mass percentage: 2-15% abrasive particles, 0.001-0.1% inhibitor, 0.001-0.5% complexing agent, and 0.01-1.5% surfactant, wherein the abrasive particles comprise silica and the core-shell structured composite abrasive particles as described in claim 1, and the amount of the composite abrasive particles is 0-10% of the total mass of the abrasive particles; the silica has a particle size of 20-100 nm and a particle size distribution index of 0.1-0.5; the chemimechanical polishing slurry has a viscosity of 0.5-2.5 mPa·s and a pH value of 8.0-12.

0.

3. The chemical mechanical polishing slurry for the copper barrier layer as described in claim 2, characterized in that, The silica has a particle size of 20-80 nm, more preferably 20-50 nm.

4. The chemical mechanical polishing slurry for the copper barrier layer as described in claim 2, characterized in that, The particle size distribution index of the silica is 0.1-0.

3.

5. The chemical mechanical polishing slurry for the copper barrier layer as described in claim 2, characterized in that, The viscosity of the chemical mechanical polishing fluid is 0.8-2.0 mPa·s.

6. The chemical mechanical polishing slurry for copper barrier layers as described in claim 2, characterized in that, The mass ratio of the complexing agent to the inhibitor is 7:1 to 1:1, preferably 3:1 to 1.5:

1.

7. The copper barrier layer chemical mechanical polishing slurry as described in claim 2, characterized in that, The polishing solution also contains hydrogen peroxide and / or potassium persulfate. Further, the polishing solution contains hydrogen peroxide and potassium persulfate, wherein the mass ratio of hydrogen peroxide to potassium persulfate is 4:1 to 1:

1.

8. The copper barrier layer chemical mechanical polishing slurry as described in claim 2, characterized in that, The mass percentage of the core-shell structured composite abrasive particles in the grinding particles is 0.01-8%, more preferably 0.1-6%.

9. The copper barrier layer chemical mechanical polishing slurry as described in claim 2, characterized in that, The complexing agent is selected from one or more of malonic acid, succinic acid, malic acid, citric acid, maleic acid, ethylenediaminetetraacetic acid, aminotrimethylphosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylphosphonic acid, pyridine-2,3-dicarboxylic acid, pyridine dicarboxylic acid, glycine, and glutamic acid diacetic acid; the inhibitor is selected from one or more of benzotriazole, 1,2,4-triazole, 5-aminotetrazolazole, 1,2-benzisothiazolin-3-one, mercaptobenzothiazole, hydroxybenzotriazole, and methylbenzotriazole.

10. The application of the copper barrier chemical mechanical polishing slurry according to any one of claims 2 to 9 in the chemical mechanical polishing of copper barrier layers.

Images