Chemical mechanical polishing solution

Abstract

This invention provides a chemical mechanical polishing slurry, comprising: abrasive particles and an organophosphate compound. The chemical mechanical polishing slurry of this invention with the added organophosphate compound exhibits a lower removal rate for phenolic resin-based hard masks, achieving a higher silica / hard mask selectivity ratio and stopping on the phenolic resin-based hard mask material.

Description

Technical Field

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

[0002] One of the challenges in photolithography patterning during semiconductor device manufacturing is that when the substrate surface has high reflectivity or when there are stepped height differences causing irregular light reflection, the patterning fidelity of the photoresist layer relative to the mask pattern is affected by irregular reflections or standing waves from the substrate surface. This can lead to reduced pattern dimensional accuracy, localized deformation, or other issues in the patterned image. With the continuous advancement of semiconductor technology, these problems related to light reflection from the substrate surface have become increasingly severe, as the wavelengths of light used for photolithography patterning have become shorter than ever before (e.g., i-line with a wavelength of 365 nm, deep ultraviolet light, and extreme ultraviolet light with a wavelength of 10-14 nm). For this short-wavelength ultraviolet light, problems caused by light reflection from the substrate surface are not limited to high-reflectivity and stepped surfaces; they can even occur on traditional substrate surfaces without particularly high reflectivity or height differences (such as silicon dioxide surfaces).

[0003] Of course, various attempts have been made to mitigate the drawbacks of reduced patterning dimensional accuracy or etching caused by light reflection from the substrate surface. One such method is the so-called ARC (anti-reflective coating) method, which involves providing an anti-reflective layer as a base coat between the substrate surface and the photoresist layer. This anti-reflective layer structure is generally called a hard mask with a photoresist underlayer. These are typically compounds containing a linear ether moiety and an aromatic moiety with a triple bond at the end. Some resin-based hard mask materials have similar structures. They are highly regarded for their excellent properties, such as good thermal conductivity, high resistivity, good radiation resistance, and low coefficient of friction. Furthermore, the addition of azo or azido organic colorants can significantly enhance their light-shielding efficiency, making them a popular choice for hard mask materials. Resin-based hard mask materials are generally classified into silicone resins, acrylic resins, polyurethane resins, phenolic resins, and alkyd resins. These hard mask materials can be formed using chemical vapor deposition (CVD), atomic deposition (ALD), and spin coating (SOC). From a cost and efficiency perspective, existing technologies typically employ spin coating (SOC) to form hard masks, using hydrocarbon-phenolic resins (such as phenolic varnish resins) and thermal crosslinking agents (such as melamine-formaldehyde resins). Due to the inherent properties of phenolic resins, the antireflective layer formed from this composition exhibits very high etch resistance, good flowability, and relatively simple production, making it an inexpensive liquid-phase processing method. These resin-based hard mask materials generally possess high plasticity; by altering their composition and annealing conditions, different substituent groups (such as halogen atoms, nitro groups, amino groups, or amino groups) can be incorporated into their structure, thereby changing their sensitivity and spreadability as hard mask materials. Phenolic resin-based hard masks generally offer advantages such as simple processing, low cost, and low-temperature processing; however, their filling effect is generally poor when filling structures with high aspect ratios, and their physical uniformity is not as good as films produced by deposition methods. In certain manufacturing processes, when dealing with substrates with steps underneath, or when a wafer contains both densely patterned and unpatterned areas, a hard mask is needed to control the thickness fluctuations of the intermediate and upper resist layers formed on them. This prevents issues such as reduced photolithography focus margin in subsequent processing steps. Furthermore, during the process, it is necessary to remove the silicon oxide layer while stopping at the hard mask layer. To ensure pattern integrity and high electrical performance, the hard mask must have an extremely low removal speed to maintain the thickness of the phenolic resin-based hard mask as much as possible. Summary of the Invention

[0004] To overcome the aforementioned technical deficiencies, the present invention aims to provide a chemical mechanical polishing (CMP) slurry. The CMP slurry of the present invention, containing an added organophosphate compound, exhibits a low removal rate for phenolic resin-type hard masks and a high silica / hard mask selectivity ratio, enabling stopping on the phenolic resin-type hard mask material.

[0005] This invention discloses a chemical mechanical polishing fluid, comprising: abrasive particles and an organophosphate compound.

[0006] Optionally, the organophosphoric acid compound includes one or more of the following: (1-hydroxyethylidene) diphosphonic acid, di(2-ethylhexyl) phosphate, diethyl hydroxymethylphosphonate, diphenyl phosphite, ethanolamine phosphate, bis(p-nitrophenyl) phosphate, phosphate betaine, 2-butoxyethanol phosphate, hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, sodium dodecylphosphonate, octadecylphosphonic acid, diethylenetriaminepentamethylidene phosphonic acid, phosphonic acid-β-styryl ester, benzyloxy polyoxyethylene ether phosphate, lauryl phosphate, and isotridecyl polyoxyethylene ether phosphate.

[0007] Optionally, the mass percentage concentration of the organophosphate compound is 0.01-1%.

[0008] Optionally, the mass percentage concentration of the organophosphate compound is 0.05-0.5%.

[0009] Optionally, the abrasive particles are silicon dioxide particles.

[0010] Optionally, the particle size range of the abrasive particles is 50nm-120nm.

[0011] Optionally, the mass percentage concentration of the grinding particles is 0.1-10%.

[0012] Optionally, the mass percentage concentration of the grinding particles is 0.5-5%.

[0013] Optionally, the polishing solution has a pH of 2-5.

[0014] Compared with existing technologies, the above technical solution has the following advantages:

[0015] 1. It has a lower removal rate for phenolic resin-type hard masks.

[0016] 2. It has a certain removal rate for silica films and a high silica / hard mask selectivity ratio, which can stop the removal of silica on phenolic resin-based hard mask materials. Detailed Implementation

[0017] The advantages of the present invention are further illustrated below through specific embodiments.

[0018] Table 1 shows the components and their contents (mass concentrations) of the chemical mechanical polishing slurry of the present invention in Comparative Examples 1-4 and Examples 1-19. According to the formulation given in the table, all components were dissolved and mixed evenly, and water was added to bring the mass percentage to 100%. The pH value of the polishing slurry was adjusted to the desired pH value using a pH adjuster.

[0019] Polishing is performed using the polishing solution formulated in Table 1 under the following conditions.

[0020] Specific polishing conditions: The polishing machine was a Reflexion LK, the polishing pad was an IC1010 polishing pad, the wafer was 300mm in diameter, the polishing pressure was 3.0psi, the polishing disc speed was 93 rpm, the polishing head speed was 87 rpm, the polishing fluid flow rate was 300ml / min, and the polishing time was 1min.

[0021] Table 1. Components and contents of the chemical mechanical polishing slurries of Comparative Examples 1-4 and Examples 1-19 of the present invention.

[0022]

[0023]

[0024] As can be seen from the test results in Table 1, based on the comparison between Comparative Example 1 and Example 1, the addition of organophosphate compounds can result in a lower removal rate of phenolic resin-type hard mask materials, and has basically no impact on the removal rate of silicon dioxide films, resulting in a higher silicon dioxide / hard mask selectivity ratio.

[0025] A comparison of Comparative Example 2 and Example 1 shows that adding only non-organophosphate compounds to the polishing slurry cannot achieve a low removal rate of phenolic resin-based hard mask materials, resulting in a low silica / hard mask selectivity ratio. Based on a comparison of Comparative Examples 3 and 4 with Example 1, a high silica / hard mask selectivity ratio cannot be obtained when the pH of the polishing slurry in this invention is outside the range of 2-5.

[0026] In summary, by controlling a reasonable pH range and the size of the abrasive particles, this invention significantly reduces the removal rate of phenolic resin-based hard mask materials by adding an organophosphate compound to the polishing solution, and achieves a high silica / hard mask selectivity ratio.

[0027] 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 slurry, characterized in that, include: Abrasive particles and organophosphate compounds.

2. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The organophosphoric acid compounds include one or more of the following: (1-hydroxyethylidene) diphosphoric acid, di(2-ethylhexyl) phosphate, diethyl hydroxymethylphosphonate, diphenyl phosphite, ethanolamine phosphate, bis(p-nitrophenyl) phosphate, phosphate betaine, 2-butoxyethanol phosphate, hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, sodium dodecylphosphonate, octadecylphosphonic acid, diethylenetriaminepentamethylidene phosphonic acid, phosphonic acid-B-styryl ester, benzoxyl polyoxyethylene ether phosphate, lauryl phosphate, and isotridecyl polyoxyethylene ether phosphate.

3. The chemical mechanical polishing slurry as described in claim 2, characterized in that, The mass percentage concentration of the organophosphate compound is 0.01-1%.

4. The chemical mechanical polishing slurry as described in claim 3, characterized in that, The mass percentage concentration of the organophosphate compound is 0.05-0.5%.

5. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The grinding particles are silicon dioxide particles.

6. The chemical mechanical polishing slurry as described in claim 5, characterized in that, The particle size range of the abrasive particles is 50nm-120nm.

7. The chemical mechanical polishing slurry as described in claim 6, characterized in that, The mass percentage concentration of the grinding particles is 0.1-10%.

8. The chemical mechanical polishing slurry as described in claim 7, characterized in that, The mass percentage concentration of the grinding particles is 0.5-5%.

9. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The pH of the polishing solution is 2-5.

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