A Chemical-Mechanical Polishing Composition and Its Application in Copper Chemical-Mechanical Polishing

Abstract

The present invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a chemical mechanical polishing composition and its application in copper chemical mechanical polishing. The chemical mechanical polishing composition provided by the present invention can effectively perform copper chemical mechanical polishing, simplify the polishing process and improve production capacity. The chemical mechanical polishing composition includes abrasive particles, a first corrosion inhibitor, a second corrosion inhibitor, a complexing agent, a surfactant, a pH regulator, an oxidizing agent and a solvent, wherein the structural formula of the first corrosion inhibitor is shown in Formula I, and the structural formula of the second corrosion inhibitor is shown in Formula II.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a chemical mechanical polishing composition and its application in copper chemical mechanical polishing. Background Art

[0002] The wiring of ultra-large scale integrated circuits is transforming from the traditional aluminum wiring process to the copper wiring process. At present, chemical mechanical polishing is the most effective process method for copper wiring planarization. Generally, the chemical mechanical polishing process of copper is divided into three steps: the first step is to use a relatively high down pressure (1.5 - 2.0 psi) to quickly and efficiently remove a large amount of copper on the substrate surface and leave a certain thickness of copper; the second step is to use a relatively low down pressure (0.5 - 1.0 psi) to remove a small amount of remaining metallic copper at a lower removal rate and stop on the barrier layer; the third step is to use a barrier layer polishing liquid to remove the barrier layer, part of the dielectric layer and a small amount of metallic copper, so as to achieve planarization. At present, all three steps of polishing require sufficient time, which makes the copper polishing process become a bottleneck in production capacity.

[0003] In order to improve the polishing rate, people are trying to combine the first two polishing steps of copper into one step. When these two steps are combined into one step (high pressure first and then low pressure) for polishing, the existing chemical mechanical polishing compositions cannot meet the polishing requirements. The chemical mechanical polishing compositions involving copper generally include abrasive particles, corrosion inhibitors, complexing agents, wetting agents, pH regulators, oxidants, etc. In order to achieve a higher removal rate, a weaker corrosion inhibitor is usually selected, and the polishing rate is regulated by changing the polishing pressure. When the two steps are combined into one step for polishing, after the high pressure is converted to the low pressure, the corrosion inhibitor cannot be adsorbed sufficiently on the copper surface, and after polishing at high pressure for a certain time, the temperature of the polishing pad is relatively high, which accelerates the corrosion rate of the copper surface, resulting in a relatively high polishing rate at low pressure and affecting the planarization effect.

[0004] US20030008599A1 discloses regulating the polishing rate of copper by introducing an oxidant and a reductant at different stages during the polishing process; US20100130101A1 discloses introducing components of polishing liquid with different compositions onto the polishing pad through two pipelines, mixing the polishing liquid online for polishing, and regulating the polishing rate by adjusting the flow rates of different components; CN103903979A also reports a method of regulating the polishing rate by supplying a polishing liquid and a polishing rate inhibitor through two pipelines respectively. All of the above methods have two problems. The first is the online mixing of chemical components, which has the problem of uneven mixing, bringing great risks to polishing planarization and wafer polishing consistency; the second is the mixing of materials with different components after polishing, which is likely to cause the aggregation of abrasive nanoparticles, shorten the service life of the polishing pad, and easily block the drain pipe of the polishing machine.

[0005] Therefore, how to develop a new chemical mechanical polishing (CMP) composition that can effectively perform chemical mechanical polishing of copper, simplify the polishing process, and improve production capacity is a problem that needs to be solved. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention obtains a new chemical mechanical polishing composition by specifically selecting and optimizing corrosion inhibitors and solvents. The composition can meet the usage requirements of combining the first two steps into one-step polishing, achieving the effects of simplifying the copper polishing process flow and improving production capacity.

[0007] Specifically, the present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a chemical mechanical polishing composition, which includes abrasive particles, a first corrosion inhibitor, a second corrosion inhibitor, a complexing agent, a surfactant, a pH regulator, an oxidizing agent, and a solvent. The first corrosion inhibitor has the structure shown in Formula I, and the second corrosion inhibitor has the structure shown in Formula II.

[0009]

[0010] In Formula (I), R1 is selected from aliphatic alkyl groups of C1-C 20 and aliphatic alkoxy groups of C1-C 20 , and n is an integer between 1 and 4;

[0011] In Formula (II), R2 is methyl or methoxy, and n is an integer between 0 and 4;

[0012] The first corrosion inhibitor and the second corrosion inhibitor are different.

[0013] In a preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the total content of the first corrosion inhibitor and the second corrosion inhibitor is 0.01 wt%-3 wt%. In a more preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the total content of the first corrosion inhibitor and the second corrosion inhibitor is 0.01 wt%-2 wt%.

[0014] In a preferred embodiment, the first corrosion inhibitor is selected from the following structures:

[0015]

[0016]

[0017] In a preferred embodiment, the second corrosion inhibitor is selected from the following structures:

[0018]

[0019] In a preferred embodiment, the weight ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:(0.1 - 10). In a specific embodiment, the weight ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or within the range formed by any two of the above values. In a most preferred embodiment, the weight ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:1.

[0020] In a preferred embodiment, the solvent comprises a first component and a second component, wherein the first component is water and the second component is an organic solvent. In a further preferred embodiment, the second component is selected from aliphatic alcohols. In a more preferred embodiment, the second component is selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, ethylene glycol, and glycerol. In a most preferred embodiment, the second component is glycerol.

[0021] In a preferred embodiment, the weight ratio of the first component to the second component of the solvent is 1:0.4 - 2.3. In a specific embodiment, the weight ratio of the first component to the second component of the solvent is 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, 1:2.3 or within the range formed by any two of the above values.

[0022] In a preferred embodiment, the abrasive particles are silica nanoparticles or alumina nanoparticles. In a more preferred embodiment, the abrasive particles are silica nanoparticles with a particle size of 30 - 160 nm.

[0023] In a preferred embodiment, the complexing agent is selected from one or more of arginine, lysine, glycine, citric acid, phosphoric acid, aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, and hydroxyethylidene diphosphonic acid. In a more preferred embodiment, the complexing agent is glycine.

[0024] In a preferred embodiment, the surfactant is a polymeric anionic surfactant selected from one or more of carboxylate-sulfonate copolymers, carboxylate-sulfonate-nonionic copolymers, and carboxylate-sulfonate-acrylate copolymers having a hydrophilic-lipophilic balance value of 15-30, wherein the salt is potassium salt and / or sodium salt. In a more preferred embodiment, the surfactant is a carboxylic acid-sulfonate copolymer kr-5000.

[0025] In a preferred embodiment, the pH regulator is selected from one or more of H3PO4, HNO3, potassium hydroxide, and ammonium hydroxide.

[0026] In a preferred embodiment, the oxidizing agent is hydrogen peroxide.

[0027] In a preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the content of the abrasive particles is 0.5 wt%-3 wt%.

[0028] In a preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the content of the complexing agent is 1 wt%-20 wt%.

[0029] In a preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the content of the surfactant is 0.005 wt%-3 wt%.

[0030] In a preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the content of the oxidizing agent is 0.1 wt%-1 wt%.

[0031] In a preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the content of the second component is at least 30 wt%. In a specific embodiment, based on the total weight of the chemical mechanical polishing composition, the content of the second component is 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt% or within the range formed by any two of the above values.

[0032] In a preferred embodiment, the pH range of the chemical mechanical polishing composition is 5 - 8. In a more preferred embodiment, the pH range of the chemical mechanical polishing composition is 6 - 7.

[0033] In a preferred embodiment, based on the total weight of the chemical mechanical polishing composition, the content of the abrasive particles is 0.5 wt% - 3 wt%, the total content of the first corrosion inhibitor and the second corrosion inhibitor is 0.01% - 3%, the content of the complexing agent is 1 wt% - 20 wt%, the content of the surfactant is 0.005 wt% - 3 wt%, the content of the oxidant is 0.1 wt% - 1 wt%, and the balance is solvent.

[0034] In a second aspect, the present invention provides the use of the chemical mechanical polishing composition described in the first aspect above in copper chemical mechanical polishing. In a preferred embodiment, the polishing method comprises the following steps: (1) the chemical mechanical polishing composition is used to remove copper on the surface of the substrate and stop on the barrier layer successively under high pressure (1.5 - 2.0 psi) and low pressure (0.5 - 1.0 psi) conditions; (2) a barrier layer polishing liquid is used to remove the barrier layer, part of the dielectric layer and a small amount of metallic copper.

[0035] The present invention has the following beneficial effects compared with the prior art:

[0036] The chemical mechanical polishing composition provided by the present invention uses two corrosion inhibitors and increases the solvent, so that when polishing under high pressure, the first corrosion inhibitor is difficult to adsorb on the surface of copper, thereby obtaining a relatively fast polishing rate. When polishing under low pressure, the first corrosion inhibitor and the second corrosion inhibitor are adsorbed on the surface of copper simultaneously, thereby reducing the polishing rate, so that the chemical mechanical polishing composition of the present invention can meet the use requirements of combining the first two steps of copper polishing into one step (high pressure first and then low pressure), achieving the effects of simplifying the copper polishing process flow and improving production capacity. Detailed Description of the Invention

[0037] The embodiments of the present invention are described in detail below. The examples given are for better explaining the content of the present invention and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The term "and / or" as used herein may include any and all combinations of one or more of the related listed items. The terms "first", "second", "third", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0039] The wt% used in this article represents weight percentage.

[0040] For those without specific technologies or conditions indicated in the examples, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments without the manufacturer indicated, they are all conventional products that can be obtained through regular channels.

[0041] Examples

[0042] The composition of the chemical mechanical polishing composition is shown in Table 1 below, where each part is in parts by weight. The abrasive particles are silica nanoparticles, the surfactant is a carboxylic acid-sulfonate copolymer kr-5000 purchased from Shandong Kerry Chemical, the first component of the solvent is water, the oxidant used is hydrogen peroxide, and hydrogen peroxide (the amount of pure hydrogen peroxide) accounts for 0.4 wt% of the total weight of the copper chemical mechanical polishing composition.

[0043] The preparation of the polishing composition includes: stirring and mixing various components evenly, adjusting the pH value to 6 with HNO3 or potassium hydroxide; adding the oxidant before use and mixing evenly.

[0044] The specific polishing conditions are as follows: the polishing machine is a 12” Reflexion LK, and the polishing pad is IC1010; the high polishing pressure is 2.0 psi, and the low polishing pressure is 1.0 psi; the rotation speeds of the polishing head and the polishing platen are 93 / 87 rpm, the flow rate of the polishing liquid is 300 mL / min, and the polishing time is 2 min. One-step polishing of metallic copper (high-pressure polishing for 1 min first and then low-pressure polishing for 1 min) is carried out. According to the real-time thickness change of the copper wafer during the polishing process and in combination with a metal film thickness meter, the polishing rate of the copper wafer under different pressure conditions is calculated.

[0045] Table 1

[0046]

[0047]

[0048] Generally, under high pressure, the polishing rate of copper is required to be greater than 6000 Å / min, and under low pressure, the polishing rate of copper is required to be in the range of 1500 - 2200 Å / min.

[0049] From the experimental results of Comparative Example 1 using only the first corrosion inhibitor, the copper removal rate under high pressure was only 3421 Å / min, far lower than the minimum requirement of 6000 Å / min for the copper polishing rate under high pressure. The copper removal rate under low pressure was only 1028 Å / min, also far lower than the required range of 1500 - 2200 Å / min for the copper polishing rate under low pressure. Obviously, neither of them meets the requirements. From the experimental results of Comparative Example 2 using only the second corrosion inhibitor, although it meets the requirement for the copper removal rate under high pressure, the copper removal rate under low pressure reached 2896 Å / min, obviously exceeding the required range of 1500 - 2200 Å / min for the copper polishing rate under low pressure. From the experimental results of Example 5, it can be seen that under the same other parameters, for the chemical mechanical composition containing both the first corrosion inhibitor and the second corrosion inhibitor, the copper polishing rate under high pressure was 6789 Å / min, and the copper polishing rate under low pressure was 1822 Å / min, both of which meet the requirements.

[0050] By comparing Examples 5 to 7 of the present invention, it can be seen that compared with n-butanol and ethylene glycol, when glycerol is used as the second component of the solvent, the polishing rate under high pressure is the highest, reaching above 7000 Å / min. In addition, glycerol has a high boiling point and is safe to use, and can be used as a preferred second component of the solvent.

[0051] By comparing Examples 7 to 9 of the present invention, it can be seen that as the weight percentage of glycerol as the second component of the solvent becomes lower and lower, the polishing rate under high pressure shows a downward trend. When the weight part of glycerol drops below 30, the polishing rate under high pressure decreases significantly, even approaching 5000 Å / min. Therefore, when glycerol is selected as the second component of the solvent, its weight part is 30 or more.

[0052] By comparing Example 10 and Example 7 of the present invention, it can be seen that when citric acid is used as the complexing agent, both the polishing rate under high pressure and the polishing rate under low pressure decrease. The polishing rate under high pressure using citric acid as the complexing agent is close to 6000 Å / min, and the polishing rate under low pressure is close to 1500 Å / min, just meeting the minimum requirement for the copper polishing rate; while the polishing rate under high pressure using glycine as the complexing agent reaches above 7000 Å / min, and the polishing rate under low pressure reaches above 1900 Å / min, both the polishing rate under high pressure and the polishing rate under low pressure are relatively high. Therefore, glycine can be used as a preferred complexing agent.

[0053] Obviously, the above embodiments are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. Those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A chemical mechanical polishing composition, characterized in that The chemical mechanical polishing composition comprises abrasive particles, a first corrosion inhibitor, a second corrosion inhibitor, a complexing agent, a surfactant, a pH adjuster, an oxidant and a solvent. The first corrosion inhibitor is selected from the following structures: and The second corrosion inhibitor is selected from the following structures: Based on the total weight of the chemical mechanical polishing composition, the total content of the first corrosion inhibitor and the second corrosion inhibitor is 0.01 wt%-3 wt%; The weight ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:(0.5-2); The solvent comprises a first component and a second component, wherein the first component is water, and the second component is an organic solvent; the second component is selected from n-butanol, ethylene glycol and glycerol; based on the total weight of the chemical mechanical polishing composition, the content of the second component is 30-70wt%; The complexing agent is selected from glycine.

2. The chemical mechanical polishing composition according to claim 1, characterized in that The weight ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:1; and / or The abrasive particles are silicon dioxide nanoparticles or aluminum oxide nanoparticles; and / or The surfactant is a polymer anionic surfactant selected from one or more of a carboxylate-sulfonate copolymer, a carboxylate-sulfonate-nonionic copolymer and a carboxylate-sulfonate-acrylate copolymer having a hydrophilic-hydrophobic balance value of 15-30; and / or The pH regulator is selected from one or more of H3PO4, HNO3, potassium hydroxide and ammonium hydroxide; and / or The oxidant is hydrogen peroxide.

3. The chemical mechanical polishing composition according to claim 2, characterized in that: The abrasive particles are silicon dioxide nanoparticles with a particle size of 30-160 nm; and / or The surfactant is carboxylic acid-sulfonate copolymer KR-5000.

4. The chemical mechanical polishing composition according to claim 3, characterized in that The second component is selected from glycerol.

5. The chemical mechanical polishing composition according to claim 4, characterized in that: The content of the second component is 40-50wt%.

6. The chemical mechanical polishing composition according to claim 1, characterized in that Based on the total weight of the chemical mechanical polishing composition, the total content of the first corrosion inhibitor and the second corrosion inhibitor is 0.01%-2%; and / or The content of the abrasive particles is 0.5%-3%; and / or The content of the complexing agent is 1%-20%; and / or The content of the surfactant is 0.005%-3%; and / or The content of the oxidant is 0.1%-1%; and / or The pH range of the chemical mechanical polishing composition is 5-8.

7. The chemical mechanical polishing composition according to claim 6, characterized in that The pH range of the chemical mechanical polishing composition is 6-7.

8. Use of the chemical mechanical polishing composition according to any one of claims 1 to 7 in chemical mechanical polishing of copper.

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