Chemical mechanical polishing liquid and use thereof

Abstract

This invention provides a chemical mechanical polishing slurry for polishing polyimide films, comprising: alumina abrasive, surfactant, and water. The polishing slurry of this invention exhibits a high polyimide film removal rate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor chemical mechanical polishing, and more specifically, to a chemical mechanical polishing slurry for polishing polyimide films with a high removal rate. Background Technology

[0002] With the continuous development of semiconductor technology, traditional monolithic integrated circuit manufacturing processes are gradually approaching their physical limits. To further improve chip performance and integration density, heterogeneous integration technology has become an important research direction. By flexibly modularizing and integrating chips of different sizes, functions, and types in three dimensions, the limitations of monolithic integrated circuits can be overcome, extending Moore's Law.

[0003] Polyimide (PI) is widely used in high-density interconnect heterogeneous chip stacks due to its excellent heat resistance, chemical resistance, insulation properties, and mechanical properties. 1) In high-density interconnect heterogeneous chip stacks, polyimide can be used as a dielectric layer, providing excellent electrical isolation and mechanical support. Its high dielectric constant and impedance characteristics help reduce signal loss and interference, improving chip performance and stability. 2) Polyimide can be used to manufacture chip packaging layers, protecting the internal structure of the chip from damage by the external environment. Its heat resistance and chemical stability allow the chip to maintain stable performance in harsh operating environments. 3) During chip stacking, polyimide can act as a buffer layer to reduce thermal and mechanical stress between different materials. This helps prevent chip damage or performance degradation due to stress concentration. 4) Polyimide can also be used to manufacture interconnects, lead frames, and other components of the chip, providing reliable electrical connections and mechanical support. 5) In some cases, polyimide can also be used as a photoresist for fabricating microstructures and patterns. Therefore, due to its wide range of applications and mature preparation process, polyimide has become one of the important materials in this field.

[0004] In recent years, the use of polyimide (PI) films as interlayer dielectrics and flexible substrates in flexible displays has increased significantly. Over the past decade, due to the hard, covalently bonded surface of polyimide films and their low polishing rate, only mechanically dominated co-processing (CMP) of polyimide films has been performed. JP2009224695A discloses a composition for PI film polishing and a method of using the composition, which includes inorganic particles, an oxidant, a pH adjuster, etc. This composition can suppress scratches on the PI surface while generating a high PI polishing rate, achieving high flatness after polishing. US7942945B1 describes a composition for polymer polishing, which consists of abrasive particles, an inorganic salt, a surfactant, and a catalyst. This composition can reduce particle adhesion to the PI surface without causing surface degradation or contamination. CN111378386A provides the use of cerium oxide abrasive in polishing PI dielectric materials, wherein the cerium oxide abrasive is mixed with a chemical mechanical polishing slurry to form a composition for use. The slurry utilizes cerium oxide as an abrasive and exhibits a high polishing rate for PI dielectric materials under appropriate cerium oxide abrasive content and a suitable pH range of the polishing slurry.

[0005] Among the many available planarization techniques, CMP has become the most important technology for manufacturing devices with multi-level metal interconnects. As film thickness increases and photolithography requirements become more stringent, there is an urgent need to develop chemical mechanical polishing slurries for PI films with high removal rates. Summary of the Invention

[0006] This invention provides a chemical mechanical polishing fluid, comprising: alumina abrasive particles, a surfactant, and water.

[0007] The abrasive particles are α-phase alumina, with a mass percentage concentration ranging from 0.5% to 5% and a particle size ranging from 100 to 500 nm.

[0008] The surfactants mentioned are anionic surfactants, nonionic surfactants, and polymeric surfactants. The anionic surfactants are sodium dodecyl sulfonate, sodium lauroyl glutamate, and sodium lauroyl sarcosinate. The nonionic surfactants are octylphenol polyoxyethylene ether and isomeric tridecyl alcohol polyoxyethylene ether. The polymeric surfactants are polyacrylic acid (molecular weight 3000-6000), polyvinylpyrrolidone (molecular weight 10,000-360,000), and polyethylene glycol (molecular weight 600-20,000).

[0009] The surfactant has a mass percentage concentration of 0.01% to 1%.

[0010] Preferably, the surfactant has a mass percentage concentration of 0.05% to 0.5%.

[0011] The pH of the chemical mechanical polishing solution is 4.0 to 7.0.

[0012] This chemical mechanical polishing slurry may also contain other commonly used additives such as pH adjusters, viscosity modifiers, and bactericides to achieve the polishing effect. Nitric acid can be used as an acidic pH adjuster; potassium hydroxide can be used as an alkaline pH adjuster.

[0013] Another aspect of this application discloses the use of the aforementioned chemical mechanical polishing slurry for polishing polyimide materials.

[0014] The chemical mechanical polishing slurry of the present invention can be prepared by the following method: the above components are mixed evenly in proportion, and the pH value is adjusted to the required value with a pH adjuster to prepare a concentrated sample. Before use, it is diluted with deionized water to the concentration range of the present invention.

[0015] Compared with existing technologies, the above technical solution has the following advantages:

[0016] 1. The polishing fluid of the present invention has an ultra-high PI removal rate.

[0017] 2. The polishing slurry of the present invention can achieve adjustable polishing rate for PI materials through reasonable combination of its components, thereby improving the applicability of the polishing slurry. Detailed Implementation

[0018] The advantages of the present invention are further illustrated below through specific embodiments, but the scope of protection of the invention is not limited to the following embodiments.

[0019] Table 1 shows comparative examples 1-6 and examples 1-12 of the chemical mechanical polishing slurry of the present invention. The components were mixed evenly. The pH was adjusted to the desired value using a pH adjuster (such as KOH or HNO3). The polishing slurry of the present invention can also be pre-prepared as a concentrated sample and diluted with deionized water at a certain ratio before use. All reagents and raw materials used in the present invention are commercially available. All contents refer to mass percentages.

[0020] The polishing slurry of the comparative and exemplary embodiments of the present invention was used to polish a fully cured polyimide film (PI2600, thickness 18 μm) under the following conditions: a Mirra polishing machine, a DuPont IC1000 polishing pad, a polishing pressure of 3.0 psi, a polishing disc and polishing head rotation speed of 93 / 87 rpm, a polishing slurry flow rate of 150 mL / min, and a polishing time of 2 min. The polishing results are shown in Table 1.

[0021] Table 1. Composition, content, and pH value of polishing solutions for Comparative Examples 1-6 and Examples 1-12

[0022]

[0023] As shown in Comparative Example 1, using silica as the abrasive resulted in a low PI removal rate. Comparative Examples 2-4, using alumina as the abrasive, showed improved PI removal rates. Compared to γ ​​and θ phase alumina, α phase alumina exhibited a higher removal rate, but still could not achieve high-speed PI removal. In Comparative Examples 5 and 6, compared to Comparative Example 4, the addition of betaine-based surfactants did not improve the removal rate. In Example 2, compared to Comparative Examples 4-6, under the same alumina abrasive conditions, the addition of a suitable surfactant significantly improved the PI polishing rate. The results of Examples 1-12 indicate that the addition of surfactants can significantly improve the PI removal rate, achieving high-speed PI film removal. The results of Examples 7-9 show that the removal rate increases with increasing surfactant content, but further increases in surfactant content result in only a slight increase in removal rate.

[0024] The polishing fluids of Examples 1-12 of this invention can achieve a high removal rate of PI film by adjusting the content and particle size of α-phase alumina abrasive and the type and content of surfactant, and by adjusting the appropriate pH.

[0025] 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: Alumina abrasive particles, surfactant, water.

2. The polishing slurry as described in claim 1, characterized in that, The grinding particles are α-phase alumina.

3. The polishing slurry as described in claim 1, characterized in that, The mass percentage concentration of the grinding particles ranges from 0.5% to 5%.

4. The polishing slurry as described in claim 1, characterized in that, The particle size range of the abrasive particles is 100–500 nm.

5. The polishing slurry as described in claim 1, characterized in that, The surfactants mentioned are anionic surfactants, nonionic surfactants, and polymeric surfactants. The anionic surfactants are sodium dodecyl sulfonate, sodium lauroyl glutamate, and sodium lauroyl sarcosinate. The nonionic surfactants are octylphenol polyoxyethylene ether and isomeric tridecyl alcohol polyoxyethylene ether. The polymeric surfactants are polyacrylic acid (molecular weight 3000-6000), polyvinylpyrrolidone (molecular weight 10,000-360,000), and polyethylene glycol (molecular weight 600-20,000).

6. The polishing slurry as described in claim 1, characterized in that, The surfactant has a mass percentage concentration of 0.01% to 1%.

7. The polishing slurry as described in claim 6, characterized in that, The surfactant has a mass percentage concentration of 0.05% to 0.5%.

8. The polishing slurry as described in claim 1, characterized in that, The pH of the chemical mechanical polishing slurry is 4.0 to 7.

0.

9. The use of a chemical mechanical polishing slurry, characterized in that, The chemical mechanical polishing slurry according to any one of claims 1 to 8 is used for polishing polyimide materials.

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