A chemical mechanical polishing liquid and use of a chemical mechanical polishing liquid

Abstract

The present application provides a chemical mechanical polishing liquid, comprising: abrasive, organic acid, five-membered nitrogen-containing heterocyclic compound, oxidizing agent and water; the abrasive is alumina. The polishing liquid of the present application has a high polyimide (PI) removal rate, and an adjustable copper (Cu) removal rate, and the PI and Cu surface roughness after polishing is low.

Description

Technical Field

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

[0002] With the continuous development of semiconductor technology and the increasing number of interconnect layers in large-scale integrated circuits, the planarization technology of conductive and insulating dielectric layers has become particularly critical.

[0003] 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. Furthermore, high-performance computing, artificial intelligence, and smart terminals are placing increasingly higher demands on chip performance and integration density. Through high-density interconnect heterogeneous chip stacking manufacturing processes, chips with different functions can be heterogeneously integrated into a single package, thereby improving bandwidth, power efficiency, and reducing latency, meeting the needs of these fields for high-performance, small-size chips.

[0004] 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.

[0005] Chemical mechanical polishing (CMP) is considered the most effective method for global planarization. CMP involves chemical, mechanical, and combined actions. It typically consists of a polishing table with a polishing pad and a polishing head to hold the chip. The polishing head holds the chip in place, and the front side of the chip is pressed against the polishing pad. During CMP, the polishing head moves linearly across the polishing pad or rotates in the same direction as the polishing table. Simultaneously, a slurry containing an abrasive is dripped onto the polishing pad and spreads out due to centrifugal force. Global planarization of the chip surface is achieved through the combined mechanical and chemical action.

[0006] In high-density interconnect heterogeneous chip stacking manufacturing processes, the flatness of the PI surface is critical. Furthermore, in some processes, the PI material comes into contact with copper, necessitating chemical mechanical polishing (CMP) to planarize the PI material while ensuring an adjustable polishing rate for copper and low surface roughness after polishing. To meet these process requirements, a CMP slurry for PI needs to be developed to achieve high-speed PI material removal with no significant scratches on the polished surface; the copper polishing rate should be adjustable, and the copper surface roughness should be low after polishing. Summary of the Invention

[0007] To overcome the aforementioned technical deficiencies, the present invention aims to provide a chemical mechanical polishing (CMP) slurry and its applications. The present invention utilizes an alumina abrasive, organic acid, a five-membered nitrogen-containing heterocyclic compound, an oxidant, and water to compose a CMP slurry, achieving a high PI removal rate and an adjustable copper (Cu) removal rate, while producing low surface roughness for both PI and Cu after polishing.

[0008] This invention discloses a chemical mechanical polishing fluid, comprising: an abrasive, an organic acid, a five-membered nitrogen-containing heterocyclic compound, an oxidant, and water; wherein the abrasive is alumina.

[0009] Optionally, the alumina abrasive is one or more of δ-phase alumina, γ-phase alumina, and θ-phase alumina.

[0010] Optionally, the mass percentage concentration of the abrasive is 0.5% to 10%.

[0011] Optionally, the particle size range of the abrasive is 50–250 nm.

[0012] Optionally, the organic acid is selected from one or two of glycine, alanine, serine, arginine, histidine, citric acid, nitrilotriacetic acid, and aspartic acid.

[0013] Optionally, the organic acid has a mass percentage content of 0.1%-2.0%.

[0014] Optionally, the nitrogen-containing heterocyclic compound is selected from one or two of 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 5-carboxy-3-amino-1,2,4-triazole, 5-acetic acid-1H-tetrazole, methylbenzotriazole, 5-phenyl-1H-tetrazole, 5-methyltetrazole, and 5-amino-1H-tetrazole.

[0015] Optionally, the mass percentage concentration of the nitrogen-containing heterocyclic compound is 0.01%-1.0%.

[0016] Optionally, the oxidant is hydrogen peroxide, with a mass percentage concentration of 0.05%-3.0%.

[0017] Optionally, the pH value of the chemical mechanical polishing fluid is 4 to 8.

[0018] The present invention also provides a use of a chemical mechanical polishing slurry for polishing polyimide materials using any of the chemical mechanical polishing slurries disclosed above.

[0019] Compared with existing technologies, the above technical solution has the following advantages:

[0020] 1. This invention can achieve a high PI removal rate and an adjustable copper (Cu) removal rate.

[0021] 2. The polishing slurry of this invention can ensure low surface roughness of PI and Cu after polishing. Detailed Implementation

[0022] The advantages of the present invention are further illustrated below through specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0023] The polishing solution of this invention may also include other commonly used additives such as pH adjusters, viscosity adjusters, and defoamers to achieve the polishing effect. The polishing solution of this invention can be concentrated and diluted with deionized water before use, and an oxidant can be added to bring it to the concentration range specified in this invention.

[0024] Specifically, according to the formulas given in Table 1, the polishing solutions of Comparative Examples 1-3 and Examples 1-10 of this application are prepared. Then, an oxidant solution of a certain concentration is mixed evenly, water is added to make up the mass percentage to 100%, and KOH or HNO3 is used to adjust the polishing solution to the required pH value.

[0025] Table 1. Composition, content, and pH of polishing solutions for Comparative Examples 1-3 and Examples 1-10

[0026]

[0027]

[0028] The polishing slurries used in Comparative Examples 1-3 and Examples 1-10 were used to polish empty PI wafers and copper wafers under the following conditions. Specific polishing conditions were: Mirra Mesa polishing machine, IC1000 polishing pad, 200mm wafer, polishing pressure 3.0 psi, polishing disk speed 93 rpm, polishing head speed 87 rpm, polishing slurry flow rate 150 ml / min, and polishing time 1 min. The surface roughness of the PI and copper wafers after polishing was measured using an XE-300P atomic force microscope. The polishing rates and surface roughness results for PI and copper are listed in Table 2.

[0029] Table 2 shows the polishing effect data for Comparative Examples 1-3 and Examples 1-10.

[0030]

[0031] As shown in Table 2, Comparative Example 1 used silica as the abrasive, which resulted in a low PI removal rate; Comparative Example 2 used α-phase alumina as the abrasive, which resulted in a high PI removal rate, but the surface roughness of the PI after polishing was very high.

[0032] Comparative Example 3 used a mixed-phase alumina of δ, γ and θ as the abrasive. Although the removal rate of PI was relatively high, the removal rate of copper was very low due to the lack of organic acids and nitrogen-containing heterocyclic compounds, which could not meet the needs of practical applications.

[0033] The polishing slurry of Examples 1-10 of the present invention uses one or more of δ-phase alumina, γ-phase alumina, and θ-phase alumina as abrasives, and adds appropriate organic acids, five-membered nitrogen-containing heterocyclic compounds and oxidants to achieve a high PI removal rate and an adjustable copper removal rate, while ensuring low surface roughness of PI and copper after polishing.

[0034] 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: It contains abrasives, organic acids, five-membered nitrogen-containing heterocyclic compounds, oxidants, and water; The abrasive is aluminum oxide.

2. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The alumina abrasive is one or more of δ-phase alumina, γ-phase alumina, and θ-phase alumina.

3. The chemical mechanical polishing slurry as described in claim 2, characterized in that, The mass percentage concentration of the abrasive is 0.5% to 10%.

4. The chemical mechanical polishing slurry as described in claim 3, characterized in that, The particle size range of the abrasive is 50–250 nm.

5. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The organic acid is selected from one or two of glycine, alanine, serine, arginine, histidine, citric acid, nitrilotriacetic acid, and aspartic acid.

6. The chemical mechanical polishing slurry as described in claim 5, characterized in that, The organic acid content is 0.1%-2.0% by mass.

7. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The five-membered nitrogen-containing heterocyclic compound is selected from one or two of 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 5-carboxy-3-amino-1,2,4-triazole, 5-acetic acid-1H-tetrazole, methylbenzotriazole, 5-phenyl-1H-tetrazole, 5-methyltetrazole, and 5-amino-1H-tetrazole.

8. The chemical mechanical polishing slurry as described in claim 7, characterized in that, The mass percentage concentration of the nitrogen-containing heterocyclic compound is 0.01%-1.0%.

9. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The oxidant is hydrogen peroxide, with a mass percentage concentration of 0.05%-3.0%.

10. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The pH value of the chemical mechanical polishing fluid is 4 to 8.

11. The use of a chemical mechanical polishing slurry, characterized in that, Used for polishing polyimide materials using a chemical mechanical polishing slurry as described in any one of claims 1 to 10.

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