Chemical mechanical polishing composition

Abstract

The invention discloses a chemical mechanical polishing composition. The composition contains abrasive particles, a corrosion inhibitor composition, an oxidizing agent, organic carboxylic acid and water. By means of the composition, tungsten polishing can be efficiently carried out, and planarization can be rapidly achieved. Wherein the additive is used to reduce dimples of different pattern sizes, densities without reducing the tungsten removal rate.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical reagents for semiconductor manufacturing, and particularly to a chemical mechanical polishing composition for tungsten polishing. Background Art

[0002] Integrated circuits are composed of millions of components on a silicon substrate, and these components are connected through multi-layer interconnect technologies. The interconnect structure usually has a first metallization layer, an interconnect layer, a second metallization layer, and usually third and subsequent metal layers. The connections between different interconnect levels are made using metal vias. With the deposition and removal of multi-layer materials, each layer of the wafer needs to be planarized. These non-planarities can lead to various defects in the product, so the planarization technology of conductive layers and insulating dielectric layers has become crucial. In the 1980s, the chemical mechanical polishing (CMP) technology pioneered by IBM was considered the most effective method for global planarization currently.

[0003] In a typical CMP process, the wafer is fixed on a face-down polishing head, and the surface of the polishing platen is covered with a polishing pad. Under a certain pressure, the polishing head moves linearly on the polishing pad or rotates along the same movement direction as the polishing table. The polishing slurry with abrasive particles flows onto the table, and under the dual action of chemistry and mechanics, the surface of the wafer is polished and global planarization is achieved. CMP can be used to remove unwanted surface topographies and surface defects, such as rough surfaces, adsorbed impurities, lattice damage, scratches, etc.

[0004] In integrated circuit design, CMP technology has become the preferred method for realizing tungsten interconnects. Tungsten is often used in the integrated circuit design of contacts / vias. Tungsten is a hard metal and chemically inert, which poses challenges to tungsten CMP. Many CMP slurries for polishing tungsten cause erosion and recession problems due to their corrosiveness. In severe cases, it leads to cavities in the dielectric layer and affects the electrical performance. Therefore, a CMP polishing method and composition for tungsten are needed, which can inhibit the corrosion of tungsten wafers, as well as the recession of tungsten and the erosion of metal line arrays.

[0005] In view of this problem, it is particularly important to develop tungsten CMP slurries that can inhibit corrosion and minimize dishing and erosion. For example, US Patent US2021340445 discloses a CMP slurry using a bicyclic amidine additive, which can provide a low-dishing and low-erosion topography. The addition of bicyclic amidine can reduce the dishing and erosion for most arrays to a certain extent. However, with the development of chip manufacturing technology, chip circuits are becoming increasingly complex, which poses higher requirements for the polishing liquid. The inhibitory effect of bicyclic amidine is not obvious, and it is difficult to adapt to the high-demand tungsten polishing environment. US Patent US 6083419 discloses a method of using amino acids as corrosion inhibitors for tungsten polishing. The addition of amino acids has a certain effect on inhibiting the corrosion of tungsten, but it will affect the normal polishing rate of tungsten during the polishing process. US Patent US10286518 discloses a tungsten polishing composition that uses a CMP method of a thiol alkoxy compound. This composition inhibits tungsten dishing and the erosion of the underlying TEOS and has the performance of further inhibiting the corrosion rate. However, its inhibitory effect in the wide-line region is average. From the above facts, it can be seen that for tungsten polishing compositions, inhibiting the corrosion of tungsten is not only challenging but also of great practical significance. Summary of the Invention

[0006] The present invention provides a chemical mechanical polishing composition, which adopts a combination of an abrasive, an organic carboxylic acid, an oxidant, a polymer, and a nitrogen-containing organic compound to obtain a polishing liquid that can have a high polishing rate, low tungsten corrosion, dishing, and erosion. The technical problem solved by the present invention is that, based on traditional tungsten corrosion inhibitors, through a combination of specific polymer and nitrogen-containing organic compound inhibitors, the corrosion (corrosion), dishing, and erosion rates of tungsten are significantly reduced, thereby reducing the defect risk and improving the yield.

[0007] The present invention discloses a chemical mechanical polishing composition, which contains: a combination of abrasive particles, a polymer, and a nitrogen-containing organic compound, an organic carboxylic acid, an oxidant, water, and a pH regulator.

[0008] Further, in the combination of the polymer and the nitrogen-containing organic compound of the chemical mechanical polishing composition, the polymer is a non-ionic polymer.

[0009] Further, in the combination of the polymer and the nitrogen-containing organic compound of the chemical mechanical polishing composition, the non-ionic polymer contains a polyoxyalkylene functional group.

[0010] Further, in the combination of the polymer and the nitrogen-containing organic compound of the chemical mechanical polishing composition, the non-ionic polymer is a homopolymer formed by polyethylene oxide or polypropylene oxide, or an ethylene oxide-propylene oxide copolymer and an ethylene oxide-acrylate copolymer.

[0011] Further, in the combination of the polymer and the nitrogen-containing organic compound in the chemical mechanical polishing composition, the non-ionic polymer is Tween.

[0012] Further, in the combination of the polymer and the nitrogen-containing organic compound in the chemical mechanical polishing composition, the nitrogen-containing organic compound is a nitrogen-containing heterocyclic organic compound.

[0013] Further, in the combination of the polymer and the nitrogen-containing organic compound in the chemical mechanical polishing composition, the nitrogen-containing organic compound is a nitrogen-containing heterocyclic amino acid organic compound.

[0014] Further, in the combination of the polymer and the nitrogen-containing organic compound in the chemical mechanical polishing composition, the nitrogen-containing organic compound is proline or histidine or tryptophan.

[0015] Further, in the combination of the polymer and the nitrogen-containing organic compound in the chemical mechanical polishing composition, the mass percentage content range of the polymer is: 0.005% to 0.5%, and the preferred mass percentage content range is: 0.005% to 0.05%.

[0016] Further, in the combination of the polymer and the nitrogen-containing organic compound in the chemical mechanical polishing composition, the mass percentage content range of the nitrogen-containing organic compound is: 0.002% to 0.2%, and the preferred mass percentage content range is: 0.002% to 0.05%.

[0017] Further, in the chemical mechanical polishing composition, the abrasive grains are selected from alumina, silica and mixtures thereof.

[0018] Further, the mass percentage content range of the abrasive grains is: 0.01% to 5%, and the preferred mass percentage content range is: 0.01% to 1.0%.

[0019] Further, in the chemical mechanical polishing composition, the organic carboxylic acid is selected from one or more of lactic acid, succinic acid, malonic acid, tartaric acid, gluconic acid, phthalic acid, malic acid, glycolic acid.

[0020] Further, the mass percentage content range of the organic carboxylic acid is: 0.01% to 5%, and the preferred mass percentage content range is: 0.1% to 3%.

[0021] Further, in the chemical mechanical polishing composition, the oxidant is hydrogen peroxide and / or iron nitrate.

[0022] Further, the mass percentage content range of the oxidant is: 0.001% to 4%.

[0023] Further, the pH value of the chemical mechanical polishing composition is 2 to 7.

[0024] After adopting the above technical solution, compared with the prior art, the following beneficial effects are obtained:

[0025] 1. The polishing composition disclosed in the present invention mainly achieves the polishing effect on tungsten through malonic acid, iron, hydrogen peroxide, and specific silica or alumina abrasives. Most importantly, compared with the traditional single chemical substance as a corrosion inhibitor, the combination of polymer and nitrogen-containing organic matter can significantly reduce the corrosion rate of the polishing liquid and reduce problems such as tungsten dents and erosion of metal wire arrays.

[0026] 2. The polishing composition disclosed in the present invention solves the problems of excessive metal corrosion, dents, and erosion existing in the tungsten polishing process. Specific Embodiments

[0027] The chemical mechanical polishing composition for polishing tungsten of the present invention will be described in detail below through specific examples to better understand the present invention. However, the following examples do not limit the scope of the present invention.

[0028] For the specific examples and comparative examples, according to the formulas given in Table 1, all components are mixed evenly, and the mass percentage is made up to 100% with water. The pH is adjusted to the desired value with a pH regulator. The polishing compositions of Examples 1-12 and Comparative Examples 1-4 are obtained. All components used in the present invention are commercially available.

[0029] Table 1 Formulas of Examples 1-12 and Comparative Examples 1-4 (the % all refer to mass percentage content)

[0030]

[0031]

[0032] According to the formulas in Table 1, experiments are carried out under the following experimental conditions, and the experimental results are shown in Table 2.

[0033] Specific polishing conditions: pressure 2.0 psi, rotational speeds of the polishing pad and polishing head 93 / 87 rpm, polishing pad IC1010, polishing liquid flow rate 300 mL / min, polishing machine tool 12” Reflexion LK, polishing time 1 min.

[0034] The morphology of the wafer surface is measured by Park systems NX-Wafer.

[0035] Static corrosion test of tungsten: Immerse a tungsten wafer of about 5 cm × 5 cm into the preheated polishing slurry at 45 degrees, immerse for 2 min, take it out and rinse, and then test the static corrosion data by the four-point probe method.

[0036] Table 2 Testing of Polishing Rate and Static Tungsten Corrosion Rate for Examples 1 - 12 and Comparative Examples 1 - 4

[0037]

[0038]

[0039] Examples 1 - 7 show that the chemical mechanical polishing liquid of the present invention can polish tungsten at a high speed. From Examples 1 - 3 and 4 - 6, it can be seen respectively that as the mass percentage content of the single component of the corrosion inhibitor increases, the corrosion rate decreases accordingly. At the same time, the tungsten depression and erosion after polishing also decrease. It should be noted that the corrosion inhibitor will inhibit the polishing speed of tungsten to a certain extent.

[0040] By comparing Comparative Example 1 with Examples 1 - 7, it is found that on the basis of the same abrasive particles, organic carboxylic acid, oxidant and pH, after adding non - ionic polymers and amino acid compositions with different concentrations and different types, the tungsten corrosion can be effectively inhibited, and the depression and erosion can be reduced.

[0041] Examples 8 - 12 show that under different pH values, different types and concentrations of abrasives, different types and concentrations of organic acids, and different oxidant conditions, ethylene oxide - propylene oxide copolymer and histidine can provide good effects in inhibiting tungsten metal corrosion, reducing depression and erosion.

[0042] By comparing Comparative Example 1 with Comparative Example 2, it is found that when adding non - ionic polymers alone, the inhibitory effects on tungsten corrosion, depression and erosion are not obvious.

[0043] By comparing Comparative Example 1 with Comparative Examples 3 and 4, it is found that when adding amino acids alone, there is still room for improvement in the inhibitory effects on tungsten corrosion, depression and erosion.

[0044] By comprehensively comparing Comparative Examples 1 - 4 and Examples 1 - 12, it is found that when non - ionic polymers and nitrogen - containing organic compounds co - exist, the best effects in inhibiting corrosion, depression and erosion can be achieved. (Relative to the static tungsten corrosion rate of 204 A / min in Comparative Example 1, with depression and erosion of 129 A and 449 A, after adding ethylene oxide - propylene oxide copolymer and histidine composition, the static corrosion of tungsten can reach 5 A / min, the depression can be reduced to 50 A, and the erosion result is as low as 168 A). The combination of corrosion inhibitors is significantly better than using a single corrosion inhibitor alone, and has a smaller inhibitory effect on the polishing speed. This discovery effectively improves the upper limit of the corrosion inhibition effect on the premise of ensuring the tungsten polishing speed, and provides a better solution for the protection of tungsten pattern wafers.

[0045] It should be understood that the "%" mentioned in the present invention all refer to mass percentage content.

[0046] In summary, the present invention discloses a chemical mechanical polishing composition. The composition contains abrasive particles, a corrosion inhibitor composition (polymer, nitrogen-containing organic compound), an oxidizing agent, an organic carboxylic acid, and water. The composition can be used for efficient tungsten polishing to quickly achieve planarization. Among them, additives are used to reduce dishing for different pattern sizes and densities without reducing the tungsten removal rate.

[0047] It should be noted that the embodiments of the present invention have better implementability and are not any form of limitation to the present invention. Any person skilled in the art may use the disclosed technical content to change or modify it into an equivalent effective embodiment. However, as long as it does not depart from the technical solution of the present invention, any modification, equivalent change, or modification made to the above embodiments according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing composition, characterized in that, Comprising: a combination of abrasive particles, a polymer and a nitrogen-containing organic compound, an organic carboxylic acid, an oxidizing agent, water and a pH regulator.

2. The chemical mechanical polishing composition according to claim 1, wherein The polymer is a non-ionic polymer.

3. The chemical mechanical polishing composition according to claim 2, wherein The non-ionic polymer contains polyoxyalkylene functional groups.

4. The chemical mechanical polishing composition according to claim 3, wherein The non-ionic polymer is a homopolymer formed from polyethylene oxide or polypropylene oxide, or an ethylene oxide-propylene oxide copolymer and an ethylene oxide-acrylate copolymer.

5. The chemical mechanical polishing composition according to claim 4, wherein The non-ionic polymer is Tween.

6. The chemical mechanical polishing composition according to claim 1, wherein The nitrogen-containing organic compound is a nitrogen-containing heterocyclic organic compound.

7. The chemical mechanical polishing composition according to claim 6, wherein The nitrogen-containing organic compound is an amino acid organic compound having a nitrogen-containing heterocycle.

8. The chemical mechanical polishing composition according to claim 7, wherein The nitrogen-containing organic compound is proline or histidine or tryptophan.

9. The chemical mechanical polishing composition according to claim 1, wherein For the combination of the polymer and the nitrogen-containing organic compound, the mass percentage content range of the polymer is: 0.005% to 0.5%, and the mass percentage content range of the nitrogen-containing organic compound is: 0.002% to 0.2%.

10. The chemical mechanical polishing composition according to claim 9, characterized in that, For the combination of the polymer and the nitrogen-containing organic compound, the mass percentage content range of the polymer is: 0.005% to 0.05%; the mass percentage content range of the nitrogen-containing organic compound is: 0.002% to 0.05%.

11. The chemical mechanical polishing composition according to claim 1, wherein The abrasive particles are selected from alumina, silica and mixtures thereof.

12. The chemical mechanical polishing composition according to claim 1, wherein The mass percentage content range of the abrasive particles is: 0.01% to 5%.

13. The chemical mechanical polishing composition according to claim 12, wherein The mass percentage content range of the abrasive particles is: 0.01% to 1.0%.

14. The chemical mechanical polishing composition according to claim 1, wherein The organic carboxylic acid is selected from one or more of: lactic acid, succinic acid, malonic acid, tartaric acid, gluconic acid, phthalic acid, malic acid, glycolic acid.

15. The chemical mechanical polishing composition according to claim 1, characterized in that, The mass percentage content range of the organic carboxylic acid is: 0.01% to 5%.

16. The chemical mechanical polishing composition according to claim 15, wherein The mass percentage content range of the organic carboxylic acid is: 0.1% to 3%.

17. The chemical mechanical polishing composition according to claim 1, wherein The oxidizing agent is hydrogen peroxide and / or iron nitrate.

18. The chemical mechanical polishing composition according to claim 1, wherein The mass percentage content range of the oxidizing agent is 0.001% to 4%.

19. The chemical mechanical polishing composition according to claim 1, wherein The pH value is 2 to 7.

Images