Chemical mechanical polishing solution for tungsten polishing

Abstract

The present application provides a chemical mechanical polishing solution for tungsten polishing, comprising: quinine base corrosion inhibitor, water, abrasive particles, catalyst, stabilizer, oxidizing agent and pH adjuster. The chemical mechanical polishing solution provided by the present application can significantly reduce the static corrosion rate of tungsten while ensuring good polishing rate of tungsten.

Description

Technical Field

[0001] This invention relates to the field of chemicals for semiconductor manufacturing, and more particularly to a chemical mechanical polishing slurry for tungsten polishing. Background Technology

[0002] Modern semiconductor technology has made the miniaturization of devices a reality. Hundreds of millions of components can be integrated onto silicon substrates for integrated circuits. These components form interconnect structures through wires and multilayer interconnects. Techniques such as physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and electrochemical plating (ECP) are used to deposit wires or interconnect structures on silicon substrates for integrated circuits, and the excess uneven material surface formed after deposition needs to be removed. With the deposition and removal of multilayer materials, the top surface of the wafer becomes uneven, and these unevennesses can lead to various defects in semiconductor products. Therefore, planarization techniques for conductive and insulating dielectric layers become crucial. Chemical mechanical polishing (CMP), pioneered by IBM in the 1980s, is considered the most effective method for global planarization. CMP consists of chemical action, mechanical action, and a combination of both. Typically, the wafer is fixed to a polishing head, with its front side in contact with a polishing pad in the CMP equipment. Under pressure, the polishing head moves linearly on the polishing pad or rotates in the same direction of motion as the polishing table. Simultaneously, a polishing composition ("slurry") is injected at a controlled flow rate between the wafer and the polishing pad. The slurry spreads evenly on the polishing pad due to centrifugal force. Thus, under the combined effects of chemical and mechanical processes, the wafer surface is polished and globally planarized. CMP can be used to remove unwanted surface morphologies and defects, such as rough surfaces, adsorbed impurities, lattice damage, scratches, etc.

[0003] In recent years, semiconductor manufacturing has increasingly used tungsten metal to fabricate through-hole connectors and contacts, while employing bonding layers such as TiN and Ti to connect them to SiO2. It is generally desirable to use CMP (Chemical Metallurgy Processing) to process the tungsten deposited layer to obtain a smooth, defect-free surface. However, unfortunately, the oxidants in the tungsten polishing slurry can corrode the metal, which is largely undesirable. This corrosion can lead to surface defects such as pitting and perforation, ultimately affecting the performance of semiconductor devices.

[0004] In the past, those skilled in the art have continuously developed novel tungsten corrosion inhibitors in hopes of solving the aforementioned problems. For example, US Patent 6136711 discloses a method using amino acids as tungsten polishing corrosion inhibitors. Today, integrated circuit manufacturing is becoming increasingly complex, placing higher demands on polishing slurries. Amino acid corrosion inhibitors generally have limited effectiveness in many systems, and when used in large quantities, they are difficult to adapt to the diverse requirements of tungsten polishing. US Patent 8865013 discloses a tungsten polishing composition containing a bis-quaternary ammonium salt corrosion inhibitor. This composition can effectively inhibit the static corrosion of metallic tungsten, but its oxidant is KIO3 instead of hydrogen peroxide, resulting in a very low tungsten polishing speed. US Patent 10597558B1 discloses a tungsten polishing composition that uses a fatty amine ethoxylate compound as a corrosion inhibitor. Although this corrosion inhibitor does not affect the polishing speed and has an inhibitory effect on defects on the substrate surface, its corrosion inhibition effect on tungsten is only about 20%.

[0005] Therefore, for tungsten polishing compositions, it is of great significance to develop corrosion inhibitors with excellent inhibition properties. Summary of the Invention

[0006] To overcome the aforementioned technical deficiencies, the present invention aims to provide a chemical mechanical polishing slurry for tungsten polishing. The chemical mechanical polishing slurry provided by the present invention can significantly reduce the static corrosion rate of tungsten while ensuring a good polishing rate.

[0007] This invention provides a chemical mechanical polishing fluid, comprising: quinine-based corrosion inhibitor, water, SiO2 abrasive particles, iron-containing catalyst, stabilizer, oxidant, and pH adjuster.

[0008] Furthermore, the quinine-based corrosion inhibitor comprises a quinoline ring and a quinoline nucleobase ring, the quinoline ring and the quinoline nucleobase ring being linked by an alkyl group. A heteroatom group is attached to the alkyl group.

[0009] Furthermore, the chemical formula of the quinine-based corrosion inhibitor is shown in Formula 1, wherein R 1 Selected from one of the following: hydrogen (H), alkoxy group (OMR), or halogen atom (F, Cl, Br); R 2 It is selected from one of the following groups: hydroxyl (-OH), mercapto (-SH), carboxyl (-COOH), amino (-NH2, -NHR, -NR2), azide (-N3), and diazo (-N2).

[0010]

[0011] Further, the quinine-based corrosion inhibitor is selected from: quinine ((6-methoxy-4-quinolinyl)(5-vinyl-1-azabicyclo[2.2.2]octane-2-yl)methanol), quinine but ((S)-[(2R,4S,5R)-5-vinyl-1-azabicyclo[2.2.2]octane-2-yl](6-methoxyquinolin-4-yl)methanol), quinine (4-quinolinyl(5-vinyl-1-azabicyclo[2.2.2]octane-2-yl)methanol), and one or more of the sulfuric acid, nitric acid, and hydrochloride salts of these compounds.

[0012] Furthermore, the quinine-based corrosion inhibitor is quinine sulfate dihydrate, the structure of which is shown in Formula 2:

[0013]

[0014] Furthermore, the mass percentage content of the corrosion inhibitor ranges from 0.005% to 0.02%.

[0015] Furthermore, the mass percentage concentration of the grinding particles ranges from 0.5% to 3%.

[0016] Furthermore, the mass percentage concentration of the grinding particles ranges from 1% to 3%.

[0017] Furthermore, the iron-containing catalyst is ferric nitrate nonahydrate.

[0018] Furthermore, the mass percentage content of the iron ion-containing catalyst ranges from 0.01% to 0.1%.

[0019] Furthermore, the mass percentage content of the iron ion-containing catalyst ranges from 0.01% to 0.03%.

[0020] Furthermore, the stabilizer is an organic stabilizer.

[0021] Furthermore, the organic stabilizer is a carboxylic acid that can complex with iron.

[0022] Furthermore, the carboxylic acid that can complex with iron is one or more of phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid, and maleic acid.

[0023] Furthermore, the stabilizer is malonic acid.

[0024] Furthermore, the stabilizer has a mass percentage content ranging from 0.01% to 0.09%.

[0025] Furthermore, the stabilizer has a mass percentage content ranging from 0.01% to 0.06%.

[0026] Furthermore, the oxidant is H2O2.

[0027] Furthermore, the oxidant has a mass percentage concentration of 2-4%.

[0028] Furthermore, the pH adjuster is HNO3.

[0029] Furthermore, the pH value of the chemical mechanical polishing solution is 2-4.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] The corrosion inhibitor selected in the chemical mechanical polishing (CMP) slurry of this invention contains quinoline nitrogen atoms and sterically hindered quinoline nitrogen atoms at the bridgehead. At pH 2-4, it produces two R3N+H structures, which adsorb onto the negatively charged tungsten surface, providing steric protection. Furthermore, since this corrosion inhibitor is a small molecule compound, it has little effect on the polishing rate of tungsten at certain concentrations. Therefore, the CMP composition provided by this invention, when used for polishing tungsten, can significantly reduce the static corrosion rate of tungsten while maintaining a good polishing rate. Detailed Implementation

[0032] The advantages of the present invention will be further illustrated below with reference to specific embodiments.

[0033] Following the formulations given in Table 1, all components were dissolved and mixed thoroughly, and water was added to bring the mass percentage to 100%. The pH was adjusted to the desired value using a pH adjuster. Polishing solutions for Examples 1-10 and Comparative Examples 1-3 were obtained. All reagents used in this invention are commercially available.

[0034] Table 1. Formulations of Examples 1-15 and Comparative Examples 1-5

[0035]

[0036]

[0037]

[0038] The polishing slurry prepared according to the formula in Table 1 was subjected to polishing rate test and tungsten static corrosion test under the following experimental conditions. The experimental results are shown in Table 2.

[0039] Specific polishing conditions: pressure 2.0psi, polishing disc and polishing head speed 93 / 87rpm, polishing pad IC1010, polishing fluid flow rate 150ml / min, polishing machine 12” Reflexion LK, polishing time 1min.

[0040] Static corrosion test procedure for tungsten: Immerse a tungsten wafer of about 3cm×3cm into a preheated polishing slurry at 45℃ for 2 minutes, remove and rinse, and then test the static corrosion data using the four-point probe method.

[0041] Table 2 Polishing rates and static corrosion test results of Examples 1-7, 11 and Comparative Examples 1-5

[0042]

[0043]

[0044] As can be seen from Tables 1 and 2, the polishing rate results of Examples 1-7 demonstrate that the chemical mechanical polishing slurry of the present invention can achieve high-speed polishing of tungsten while also exhibiting a moderate polishing rate for silicon oxide. Importantly, the polishing composition exhibits a very low static corrosion rate in the presence of the corrosion inhibitor quinine base. Furthermore, the experimental results of Examples 1 and 5-7 show that, especially when using the preferred quinine sulfate dihydrate, the corrosion inhibition effect of the polishing slurry on tungsten gradually increases with increasing amounts of corrosion inhibitor. Notably, in the presence of 0.02% quinine sulfate dihydrate, static corrosion can be reduced to below 10 A / min. It should be noted that the quinine base corrosion inhibitor slightly inhibits the polishing rate of tungsten to some extent. While the static corrosion rate of tungsten gradually decreases with increasing concentration of the corrosion inhibitor, the polishing rate of tungsten also decreases accordingly, but the polishing rate of silicon oxide remains unaffected. Therefore, the polishing slurry of the present invention can achieve appropriate adjustment of the relative polishing rates for tungsten and silicon oxide.

[0045] Furthermore, a comparison between Comparative Examples 1-2 and Examples 1-7, 11 revealed that, with the same grinding particles, catalyst, stabilizer, oxidant, and pH, the addition of a quinine-based corrosion inhibitor effectively suppressed the static corrosion of tungsten (the static corrosion rate of tungsten in the comparative examples was significantly lower). The above points indicate that, after adding quinine, an alkaline corrosion inhibitor, the static corrosion of tungsten cannot be reduced to [a certain level]. Below, and able to achieve about.

[0046] Furthermore, a comparison of Comparative Examples 3-4 with Examples 1 and 11 reveals that other compounds containing quinine base fragments, such as quinoline, do not exhibit corrosion inhibition effects on tungsten materials.

[0047] A comparison between Comparative Example 5 and Example 1 revealed that compounds containing quinine-like quinine ring fragments, such as triethylenediamine, also failed to inhibit corrosion in tungsten materials.

[0048] A comparison of Comparative Examples 3 and 5 with Example 1 revealed that the corrosion inhibition effect of quinine base is produced by the synergistic effect of multiple functional groups. Compounds containing only some or similar functional groups cannot achieve the corrosion inhibition effect on tungsten materials.

[0049] 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 chemical mechanical polishing liquid for polishing tungsten, characterized by comprising: a colloidal silica abrasive; and a surfactant. The application relates to a chemical mechanical polishing liquid, which comprises: quinine base corrosion inhibitors, water, SiO2 abrasive particles, iron ion-containing catalysts, stabilizers, oxidants and pH regulators; The mass percentage content of the corrosion inhibitors ranges from 0.005% to 0.02%; the mass percentage content of the abrasive particles ranges from 0.5% to 3%; the mass percentage content of the iron ion-containing catalysts ranges from 0.01% to 0.1%; the stabilizer is a carboxylic acid capable of complexing with iron; the mass percentage content of the stabilizer ranges from 0.01% to 0.09%; the mass percentage content of the oxidant ranges from 2% to 4%; and the pH value of the chemical mechanical polishing liquid ranges from 2 to 4. The quinine base corrosion inhibitors are selected from one or more of quinine, quinine butyl, cinchona, and sulfuric acid, nitric acid and hydrochloric acid salts of these compounds.

2. The chemical mechanical polishing liquid according to claim 1, wherein The quinine base corrosion inhibitors are quinine sulfate dihydrate, the structure of which is shown in the following formula: 。 3. The chemical mechanical polishing liquid according to claim 1, wherein The mass percentage content of the abrasive particles ranges from 1% to 3%.

4. The chemical mechanical polishing liquid according to claim 1, wherein The iron ion-containing catalysts are iron nitrate nonahydrate.

5. The chemical mechanical polishing liquid according to claim 1, wherein The mass percentage content of the iron ion-containing catalysts ranges from 0.01% to 0.03%.

6. The chemical mechanical polishing liquid according to claim 1, wherein The carboxylic acid capable of complexing with iron is one or more of phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid and maleic acid.

7. The chemical mechanical polishing liquid according to claim 1, wherein The stabilizer is malonic acid.

8. The chemical mechanical polishing liquid according to claim 1, wherein The mass percentage content of the stabilizer ranges from 0.01% to 0.06%.

9. The chemical mechanical polishing liquid according to claim 1, wherein The oxidant is H2O2.

10. The chemical mechanical polishing liquid according to claim 1, wherein The pH regulator is HNO3.

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