Chemical mechanical polishing composition for STI structure polishing and application thereof

Abstract

The invention discloses a chemical mechanical polishing composition for an STI structure and application of the chemical mechanical polishing composition, cerium dioxide is used as an abrasive material in the chemical mechanical polishing composition, and meanwhile, a defoaming agent, a passivating agent, an antioxidant and a pH regulator are added. The chemical mechanical polishing composition provided by the invention not only can improve the polishing rate of an oxide layer, but also can adjust the selection ratio of TEOS / Si3N4, and effectively inhibits the generation of defects after polishing.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, and in particular to a chemical mechanical polishing composition for STI structure polishing and application thereof. Background Art

[0002] In ultra-large-scale integrated circuit (ULSI) manufacturing, the shallow trench isolation (STI) structure achieves complete isolation between devices by eliminating leakage current between the N-well and P-well. The formation of the STI structure first forms a shallow trench between active devices and deposits gap filling materials such as silicon dioxide on the trench. After these processes, the step height of the gap filling material is inevitably formed, which needs to be eliminated.

[0003] Chemical mechanical polishing (CMP) can eliminate the step height of the gap filling material and stop it on the silicon nitride film. As the feature size of integrated circuits (ICs) continues to be miniaturized and the distance between transistors continues to decrease, the STI CMP process requires excellent selectivity between the protective layer silicon nitride (Si3N4) and silicon dioxide material (SiO2), so that the patterned nitride film layer can be protected and the loss of the nitride film layer can be reduced even when over-polishing is performed. In addition, when polishing the patterned wafer, the amount of dishing of the insulating film can be reduced.

[0004] The most commonly used abrasives in STI CMP are ceria and fumed silica. However, compared with fumed silica abrasives, ceria abrasives have a higher polishing rate and higher selectivity for oxides and nitrides, so ceria abrasives are the most commonly used in STI CMP. However, ceria abrasives are more likely to aggregate, and surfactants need to be added to reduce the interaction between particles. The presence of surfactants makes it easy to form bubbles on the oxide surface during the polishing process, reducing the contact area between the abrasive and the oxide, and reducing the polishing rate of the oxide.

[0005] Therefore, there is still a need to develop a chemical mechanical polishing composition suitable for STI structure, which can adjust the polishing selectivity of SiO2 and Si3N4 and improve the polishing rate by using relatively low abrasive concentration and suitable chemical additives to obtain better wafer surface quality. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a chemical mechanical polishing composition for STI CMP, which improves the polishing rate of cerium oxide abrasive by adding antioxidants and defoaming agents, and adjusts the polishing selectivity of SiO2 and Si3N4 by adjusting the ratio of two passivating agents to obtain better wafer surface quality.

[0007] Another object of the present invention is to provide application of the cerium oxide polishing solution in STI chemical mechanical polishing.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0009] A chemical mechanical polishing composition for STI structure comprises the following components: cerium dioxide abrasive, a passivating agent, a defoaming agent, an antioxidant, a pH regulator and deionized water.

[0010] In a specific embodiment, based on the total mass of the chemical mechanical polishing composition, the chemical mechanical polishing composition includes: 0.1-1wt% cerium oxide abrasive, 0.02-0.5wt% antioxidant, 0.5-3wt% passivator, 0.001-0.2wt% defoamer, pH regulator and deionized water.

[0011] In a specific embodiment, the abrasive is selected from cerium dioxide, and the particle size is 100-200 nm, preferably 150 nm.

[0012] In a specific embodiment, the antioxidant is at least one of hydroquinone, gallic acid, ascorbic acid, tert-butylphenol, bisphenol A, phloroglucinol, 3,4-dihydroxyphenylethanol, lipoic acid, and phenethylresorcinol, preferably gallic acid, lipoic acid, hydroquinone, and phenethylresorcinol, and more preferably lipoic acid.

[0013] In a specific embodiment, the passivating agent is a compound containing hydroxyl and / or carboxyl functional groups.

[0014] In a preferred embodiment, the passivator is a two-component passivator, selected from at least two of polyacrylic acid, polyacrylic acid-polyethylene glycol, polyvinyl alcohol, polyacrylamide, polyacrylic acid-polyacrylamide, polyacrylic acid-polyvinyl ether, benzoic acid, p-hydroxybenzoic acid, terephthalic acid, picolinic acid, glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine and histidine.

[0015] In a more preferred embodiment, the two-component passivator is a combination of any two of p-hydroxybenzoic acid, polyvinyl alcohol, and polyacrylic acid-polyethylene glycol.

[0016] In a more preferred embodiment, the mass ratio of the two passivators in the two-component passivator is 10%-80%:90%-20%, for example, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, etc.; preferably 20%-60%:80%-40%.

[0017] In a more preferred embodiment, the molecular weight of the polyvinyl alcohol is 9000-12000, the molecular weight of the polyacrylic acid in the polyacrylic acid-polyethylene glycol is 4000-6000, and the molecular weight of the polyethylene glycol is 4000-5000.

[0018] In a specific embodiment, the defoaming agent is polypropylene glycol.

[0019] In a specific embodiment, the pH adjuster is selected from any one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, citric acid, oxalic acid, acetic acid, potassium hydroxide, ammonium hydroxide, tetraalkylammonium hydroxide, ethanolamine, and diethanolamine, preferably potassium hydroxide or nitric acid; preferably, the pH of the chemical mechanical polishing composition is controlled at 4-6.

[0020] On the other hand, the aforementioned polishing composition is used in shallow trench chemical mechanical polishing, especially in the surface polishing of silicon oxide and silicon nitride.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Compared with the existing polishing liquid, the polishing composition of the present invention has the advantages of fast removal rate and high selectivity. In addition, antioxidants and defoamers are added to the polishing composition. The antioxidant can reduce Ce 3+ Convert to Ce 4+ The defoaming agent can reduce the generation of bubbles on the oxide surface and increase the formation of Ce-O-Si bonds, thereby increasing the oxide removal rate. In addition, the polishing composition also adds a passivating agent to effectively adjust the silicon oxide / silicon nitride removal rate and the silicon oxide / silicon nitride removal rate selectivity, effectively inhibiting the generation of polishing defects. Compared with the prior art, it has significant advantages. DETAILED DESCRIPTION

[0023] In order to better understand the technical solution of the present invention, the following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the claims of the present invention.

[0024] A chemical mechanical polishing composition for shallow groove polishing comprises deionized water, cerium dioxide abrasive, antioxidant, defoaming agent, passivating agent and pH regulator.

[0025] Wherein, the abrasive is cerium dioxide abrasive; the amount of the abrasive added is 0.1-1wt% of the total mass of the polishing composition, for example including but not limited to 0.1wt%, 0.2wt%, 0.3wt%, 0.5wt%, 0.8wt%, 1wt%, preferably 0.3wt%; the particle size of the abrasive is 100-200nm, preferably 150nm.

[0026] The antioxidant is preferably lipoic acid, and the amount of the antioxidant added is 0.02-0.5wt% of the mass of the polishing composition, for example including but not limited to 0.02wt%, 0.06wt%, 0.08wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, preferably 0.1-0.3wt%.

[0027] The passivator is a two-component compound containing carboxyl and / or hydroxyl functional groups, preferably selected from any two combinations of polyacrylic acid-polyethylene glycol, polyvinyl alcohol, and p-hydroxybenzoic acid. There is no particular restriction on the ratio of the two passivators in the two-component passivator, preferably the mass ratio of the two passivators is 10%-80%: 90%-20%; preferably 20%-60%: 80%-40%. The amount of the passivator added is 0.5-3wt% of the mass of the polishing composition, for example, including but not limited to 0.5wt%, 0.15wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.6wt%, 2wt%, 2.5wt%, 3wt%, preferably 0.5-2wt%.

[0028] The defoaming agent is polypropylene glycol, and the amount of the defoaming agent added is 0.001-0.2wt% of the mass of the polishing composition, for example including but not limited to 0.005wt%, 0.01wt%, 0.1wt%, 0.15wt%, 0.2wt%, preferably 0.03wt%.

[0029] The pH adjuster includes but is not limited to nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, citric acid, oxalic acid, acetic acid, potassium hydroxide, ammonium hydroxide, tetraalkylammonium hydroxide, ethanolamine, diethanolamine, preferably KOH or HNO3. The pH is adjusted according to the pH requirement to control the pH of the polishing composition between 4-6.

[0030] The present invention is further explained below by more specific examples, but they do not constitute any limitation.

[0031] The main sources or specifications of the raw materials involved in the following examples are as follows:

[0032] The cerium oxide abrasive is a nano-cerium oxide abrasive synthesized by a hydrothermal method and is sourced from Solvay, and polyvinyl alcohol, polyacrylic acid-polyethylene glycol, p-hydroxybenzoic acid, lipoic acid, and polypropylene glycol are all sourced from Sigma-Aldich.

[0033] The specific polishing conditions are as follows: the polishing machine is 12” Ebara F-REX300X, the polishing pad is IC 1010; the polishing pressure is 3 psi; the polishing head and polishing disc speed is 93 / 87 rpm, the polishing liquid flow rate is 300 mL / min, and the polishing time is 60 s.

[0034] Example

[0035] The types and contents of substances added to the polishing liquid formulas used in the embodiments and comparative examples are shown in Table 1. Each component is calculated based on the content of the pure substance and is configured according to the formula in the table. The balance is made up to 100% with deionized water, and the pH value is adjusted with potassium hydroxide or nitric acid.

[0036] Table 1 Types and contents of polishing liquid formulas in Examples and Comparative Examples

[0037]

[0038]

[0039]

[0040] Table 1 presents the specific ingredients of the comparative examples and the examples. The prepared chemical mechanical polishing compositions are used for polishing STI. Table 2 presents the specific data of the removal rates and selectivities of TEOS and Si3N4.

[0041] Table 2 TEOS and Si3N4 removal rates and selectivity of comparative examples and embodiments

[0042]

[0043] From the results of the embodiment and comparative examples 1, 4 and 5, it can be seen that the polishing rate of silicon dioxide is greatly improved by adding a passivating agent and an antioxidant, and the polishing rate of silicon nitride is reduced, with a very high polishing rate selectivity of silicon nitride to silicon dioxide. By adjusting the ratio of the two passivating agents added, the selectivity of silicon oxide to silicon nitride is effectively adjusted, and polishing defects are effectively reduced to a certain extent.

[0044] The passivating agent involved in this patent contains hydroxyl or carboxyl functional groups, which can be adsorbed on the surface of silicon nitride under acidic conditions through opposite charge attraction and hydrogen bond interaction, which not only reduces the interaction between the abrasive particles and the silicon nitride surface, but also inhibits the hydrolysis reaction of Si-OH in silicon nitride, resulting in a significant reduction in the Si3N4 removal rate.

[0045] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention. Those skilled in the art will appreciate that, under the guidance of this specification, some modifications or adjustments may be made to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A chemical mechanical polishing composition for STI structure, characterized in that: The invention comprises the following components: cerium dioxide abrasive, a passivating agent, a defoaming agent, an antioxidant, a pH adjusting agent and deionized water.

2. The chemical mechanical polishing composition according to claim 1, characterized in that Based on the total weight of the chemical mechanical polishing composition, the chemical mechanical polishing composition comprises: 0.1-1wt% of cerium oxide abrasive, 0.02-0.5wt% of antioxidant, 0.5-3wt% of passivator, 0.001-0.2wt% of defoamer, pH regulator and deionized water.

3. The chemical mechanical polishing composition according to claim 1 or 2, characterized in that: The passivating agent is a compound containing hydroxyl and / or carboxyl functional groups; Preferably, the passivator is a two-component passivator, selected from at least two of polyacrylic acid, polyacrylic acid-polyethylene glycol, polyvinyl alcohol, polyacrylamide, polyacrylic acid-polyacrylamide, polyacrylic acid-polyvinyl ether, benzoic acid, p-hydroxybenzoic acid, terephthalic acid, picolinic acid, glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine and histidine; More preferably, the two-component passivator is a combination of any two of p-hydroxybenzoic acid, polyvinyl alcohol, and polyacrylic acid-polyethylene glycol.

4. The chemical mechanical polishing composition according to claim 3, characterized in that The mass ratio of the two passivators in the two-component passivator is 10%-80%:90%-20%; preferably 20%-60%:80%-40%.

5. The chemical mechanical polishing composition according to claim 3, characterized in that: The molecular weight of the polyvinyl alcohol is 9000-12000, the molecular weight of the polyacrylic acid in the polyacrylic acid-polyethylene glycol is 4000-6000, and the molecular weight of the polyethylene glycol is 4000-5000.

6. The chemical mechanical polishing composition according to claim 1 or 2, characterized in that: The defoaming agent is polypropylene glycol.

7. The chemical mechanical polishing composition according to claim 1 or 2, characterized in that: The antioxidant is at least one of hydroquinone, gallic acid, ascorbic acid, tert-butylphenol, lipoic acid, bisphenol A, phloroglucinol, 3,4-dihydroxyphenylethanol, resveratrol, and phenethylresorcinol, preferably lipoic acid.

8. The chemical mechanical polishing composition according to claim 1 or 2, characterized in that: The pH adjuster is selected from any one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, citric acid, oxalic acid, acetic acid, potassium hydroxide, ammonium hydroxide, tetraalkylammonium hydroxide, ethanolamine, and diethanolamine, preferably potassium hydroxide or nitric acid.

9. The chemical mechanical polishing composition according to claim 1 or 2, characterized in that: The pH of the chemical mechanical polishing composition is controlled between 4-6.

10. Use of the chemical mechanical polishing composition for STI structure according to any one of claims 1 to 9 in surface polishing of silicon oxide and silicon nitride.

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