A chemical mechanical polishing slurry and its application

Abstract

The invention relates to the technical field of polishing liquid, and in particular to a chemical mechanical polishing slurry, which comprises, by mass percentage, 0.005-2% of a phosphate surfactant, 0.1-10% of abrasive particles, 0.01-15% of a complexing agent, 0.01-2% of a corrosion inhibitor, 0.05-10% of an oxidant, and the remainder is water. The polishing slurry of the invention can be used for chemical mechanical polishing of copper. The invention has a lower solid content, thereby reducing surface contamination; the rate is adjusted by regulating the ratio of the complexing agent to the corrosion inhibitor, thereby meeting the needs in most cases; when the concentration is high, it can be made into a concentrated liquid with stable performance and good concentration effect, and it can be diluted according to a certain ratio when used, so that the transportation and packaging costs can be reduced, and it has been found through testing that the chemical mechanical polishing liquid can still maintain a higher rate under the condition of a high dilution ratio; a non-ionic surfactant is added, which can ensure that the surface flatness and smoothness of the material after polishing are high, and reduce the number of scratches.

Description

Technical Field

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

[0002] With the rapid development of microelectronics technology, the integration of very large scale integrated circuit (VLSI) chips has reached billions of components, and the feature size is constantly entering the nanometer level. This trend has put forward higher requirements for hundreds of processes in microelectronics technology, especially in multi-layer wiring, substrate and dielectric processing, where chemical mechanical planarization (CMP) technology is particularly important.

[0003] In terms of wiring materials, VLSI is undergoing a transition from traditional aluminum (Al) to copper (Cu). Compared with aluminum, copper has significant advantages in many aspects, including lower resistivity, higher resistance to electromigration, and shorter RC delay time. These advantages make copper an ideal interconnect metal in semiconductor manufacturing, gradually replacing aluminum.

[0004] However, there is currently no effective plasma etching or wet etching technology that can fully realize the application of copper interconnects in integrated circuits. Therefore, the chemical mechanical polishing method of copper is recognized as the most effective process at present, which can meet the manufacturing needs of higher integrated chips while ensuring the quality of copper interconnects. By continuously optimizing the CMP process, engineers expect to further improve the performance of copper interconnects and promote the development of microelectronics technology to a higher level.

[0005] The chemical mechanical polishing (CMP) process for copper is usually divided into three main steps. The first step uses a high down force to remove a large amount of copper on the substrate surface at a fast and efficient removal rate. The second step is to reduce the down force when approaching the barrier layer, thereby slowing the removal rate so that the remaining metal copper can be accurately polished and stay on the barrier layer. The third step uses a special barrier layer polishing liquid to remove the barrier layer and part of the dielectric layer and metal copper to achieve surface flatness. In both the first and second steps, copper chemical mechanical polishing liquid is used to ensure good polishing results.

[0006] During the copper polishing process, two requirements need to be balanced. On the one hand, the excess copper on the barrier layer must be removed as quickly as possible; on the other hand, the butterfly depression of the copper wire after polishing must be minimized. Before the copper polishing begins, there is usually a certain depression on the surface of the copper wire. During the polishing process, the copper on the dielectric material is easily removed under the higher body pressure, while the copper in the depression is subjected to a relatively low polishing pressure, resulting in a reduced removal rate. As the polishing progresses, the height difference of the copper gradually decreases, and finally flattening is achieved.

[0007] However, during the polishing process, if the chemical action of the copper polishing solution is too strong and the static corrosion rate is too high, the copper passivation film may be excessively removed even at lower pressures (such as in copper wire depressions). This situation will lead to reduced planarization efficiency and increase the degree of butterfly depression after polishing. Therefore, in practical applications, it is crucial to control the balance between the chemical properties of the polishing solution and the polishing pressure to ensure the best planarization effect of the copper wire while avoiding unnecessary defects. By optimizing these parameters, engineers can improve the quality and reliability of copper interconnects and provide strong support for the manufacture of very large-scale integrated circuits.

[0008] At present, copper polishing slurries have made some technological innovations, but there are still some shortcomings. For example, the polishing speed of some slurries is not ideal, resulting in low polishing efficiency; after use, defects, scratches, sticky stains and copper residues may appear on the substrate surface. In addition, the degree of depression of the copper block after polishing may be too large, which affects the quality of the final product. During the polishing process, there may also be problems of local or overall corrosion, and the static corrosion rate of copper at room temperature and polishing temperature (such as 50°C) is high, all of which have a negative impact on the polishing effect.

[0009] Therefore, it is particularly necessary to develop a new type of copper chemical mechanical polishing slurry. Summary of the invention

[0010] The technical problem to be solved by the present invention is to overcome the defects of the existing chemical mechanical polishing liquid having a high solid content, requiring high stress during polishing, and easily causing corrosion of metal and dielectric materials, and to provide a chemical mechanical polishing slurry for copper that can adjust the copper removal rate, improve the surface quality after polishing, has a high concentration, and contains ultra-low abrasive. The polishing slurry contains at least one non-ionic surfactant, and the slurry also contains an abrasive, a complexing agent, a corrosion inhibitor, and an oxidant. The slurry of the present invention can be used to adjust the required copper removal rate by adjusting the mass ratio of the complexing agent to the corrosion inhibitor, and obtain a material with a smooth surface and no scratches.

[0011] In order to solve the above technical problems, the present invention is implemented by the following technical solutions: A chemical mechanical polishing slurry, calculated by mass percentage, comprises:

[0012]

[0013] As a preferred embodiment, the phosphate surfactant is At least one of .

[0014] As a preferred solution, the weight percentage of the phosphate surfactant is 0.01-1%.

[0015] As a preferred embodiment, the abrasive particles are silicon dioxide, aluminum oxide, cerium dioxide, titanium dioxide and / or polymer abrasive particles.

[0016] As a preferred solution, the particle size of the abrasive particles is 20 to 140 nm.

[0017] As a preferred embodiment, the complexing agent is an aminocarboxylic acid compound (a compound containing an aminocarboxyl group), an organic carboxylic acid, or an organic phosphonic acid.

[0018] As a preferred embodiment, the aminocarboxylic acid compound is selected from at least one of glycine, alanine, valine, leucine, proline, phenylalanine, tyrosine, tryptophan, lysine, arginine, histidine, serine, aspartic acid, threonine, glutamic acid, asparagine, glutamine, nitrilotriacetic acid, ethylenediaminetetraacetic acid, cyclohexanetetraacetic acid, and ethylenediamine disuccinic acid; the organic carboxylic acid is at least one of acetic acid, oxalic acid, citric acid, tartaric acid, malonic acid, succinic acid, malic acid, lactic acid, gallic acid, and sulfosalicylic acid; and the organic phosphonic acid is at least one of 2-phosphonobutane-1,2,4-tricarboxylic acid, aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepenta(methylenephosphonic acid), 2-hydroxyphosphonoacetic acid, ethylenediaminetetramethylenephosphonic acid, and polyaminopolyether-methylenephosphonic acid.

[0019] As a preferred embodiment, the corrosion inhibitor is an azole compound, the azole compound is selected from at least one of BTA and its derivatives, preferably 1,2,4-triazole, and the mass ratio of the complexing agent to the corrosion inhibitor is 1:1 to 20:1.

[0020] As a preferred embodiment, the oxidant is selected from at least one of hydrogen peroxide, urea peroxide, performic acid, peracetic acid, persulfate, percarbonate, periodic acid, perchloric acid, perboric acid, potassium permanganate and ferric nitrate.

[0021] The polishing liquid of the present invention may also contain other conventional additives in the art, such as pH regulators, defoamers, and bactericides to achieve the desired polishing effect.

[0022] The polishing liquid of the present invention can be prepared as a concentrated sample, which is diluted with deionized water to a desired concentration range and an oxidant is added before use.

[0023] The polishing slurry of the present invention can be used for chemical mechanical polishing of copper.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The chemical mechanical polishing liquid of the present invention has a low solid content, that is, the content of abrasive particles is very low, so that the amount of surface contamination can be controlled within a low range;

[0026] (2) The chemical mechanical polishing solution of the present invention can adjust the rate by regulating the ratio of the complexing agent to the corrosion inhibitor, thereby meeting the requirements in most cases;

[0027] (3) The chemical mechanical polishing liquid of the present invention can be made into a concentrated liquid with stable performance when the concentration is high, and the concentration effect is good. When used, it can be diluted according to a certain ratio, which can reduce the transportation and packaging costs. It has been found through testing that the chemical mechanical polishing liquid can still maintain a high rate under high dilution ratio conditions;

[0028] (4) The chemical mechanical polishing liquid of the present invention is added with a non-ionic surfactant, which can ensure that the surface flatness and smoothness of the material after polishing are high and the number of scratches is reduced. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] Examples 1-20 and Comparative Examples 1-2

[0032] Table 1 shows examples 1 to 20 and comparative examples 1 to 2 of the chemical mechanical polishing solution of the present invention. According to the formula shown in the table, the components other than the oxidant are mixed evenly, and the mass is supplemented with water to 100% at any time, and the required pH is adjusted with 48wt% KOH or 10wt% HNO3, and the pH adjuster is added before use, and mixed evenly.

[0033] Table 1 Polishing liquid formulations and polishing effects of various embodiments and comparative examples

[0034]

[0035]

[0036]

[0037] The present invention adopts Huahai Qingke U300B machine, the polishing pad is: IC1010 pad, the polishing pressure is: RR / Z1 / Z2 / Z3 / Z4 / Z5=6.9 / 6.6 / 3.3 / 3.0 / 0.0 / 2.85psi, the polishing head / disc speed is: 87 / 93rpm, and the flow rate is 250ml / min.

[0038] According to the data in Table 1, compared with the comparative example 1 without adding abrasive, the removal rate of Examples 1 to 5 was significantly improved after adding abrasive. When the mass percentage of abrasive reached 3% to 5%, the removal rate no longer continued to increase, and the polishing slurry was still in a low abrasive state. This shows that the addition of abrasive within a certain range (3% to 5%) can effectively improve the removal rate.

[0039] In addition, compared with Comparative Example 2 in which the mass ratio of the complexing agent to the corrosion inhibitor was 1:1, the mass ratio in Examples 6 to 9 was adjusted from 3:1 to 13:1. It was observed that when the mass ratio exceeded 10:1, the removal rate began to decrease. This phenomenon indicates that by controlling the ratio of the complexing agent to the corrosion inhibitor within an appropriate range (10:1 to 13:1), the removal rate of the polishing slurry of the present invention can be flexibly adjusted to meet different application requirements.

[0040] Examples 10 to 15 further demonstrate that the addition of nonionic surfactants significantly improves the surface quality of the material after polishing, and the scratches almost completely disappear. This result emphasizes the importance of surfactants in improving the polishing effect.

[0041] Examples 16 to 20 show that after the concentrate is diluted fifteen times and hydrogen peroxide is added, the removal rate can still reach This result shows that the concentrated stock solution of the polishing liquid has a significant effect and can maintain a high removal rate after dilution, further verifying the superior performance of the polishing slurry of the present invention.

[0042] The above are preferred implementation modes of the present invention. Those skilled in the art to which the present invention belongs can also change and modify the above implementation modes. Therefore, the present invention is not limited to the above specific implementation modes. Any obvious improvements, substitutions or modifications made by those skilled in the art on the basis of the present invention belong to the protection scope of the present invention.

Claims

1. A chemical mechanical polishing slurry, characterized in that: In terms of mass percentage, it includes: The balance is water.

2. The chemical mechanical polishing slurry according to claim 1, characterized in that: The phosphate surfactant is At least one of .

3. The chemical mechanical polishing slurry according to any one of claims 1 or 2, characterized in that: The weight percentage of the phosphate surfactant is 0.01-1%.

4. The chemical mechanical polishing slurry according to claim 1, characterized in that: The abrasive particles are silicon dioxide, aluminum oxide, cerium dioxide, titanium dioxide and / or polymer abrasive particles, and the particle size of the abrasive particles is 20 to 140 nm.

5. The chemical mechanical polishing slurry according to claim 1, characterized in that: The complexing agent is an aminocarboxylic acid compound, an organic carboxylic acid, or an organic phosphonic acid.

6. The chemical mechanical polishing slurry according to claim 5, characterized in that: The aminocarboxylic acid compound is selected from at least one of glycine, alanine, valine, leucine, proline, phenylalanine, tyrosine, tryptophan, lysine, arginine, histidine, serine, aspartic acid, threonine, glutamic acid, asparagine, glutamine, nitrilotriacetic acid, ethylenediaminetetraacetic acid, cyclohexanetetraacetic acid, and ethylenediamine disuccinic acid; the organic carboxylic acid is at least one of acetic acid, oxalic acid, citric acid, tartaric acid, malonic acid, succinic acid, malic acid, lactic acid, gallic acid, and sulfosalicylic acid; the organic phosphonic acid is at least one of 2-phosphonobutane-1,2,4-tricarboxylic acid, aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepenta(methylenephosphonic acid), 2-hydroxyphosphonoacetic acid, ethylenediaminetetramethylenephosphonic acid, and polyaminopolyethermethylenephosphonic acid.

7. The chemical mechanical polishing slurry according to claim 1, characterized in that: The corrosion inhibitor is an azole compound.

8. The chemical mechanical polishing slurry according to claim 1, characterized in that: The mass ratio of the complexing agent to the corrosion inhibitor is 1:1 to 20:

1.

9. The chemical mechanical polishing slurry according to claim 1, characterized in that: The oxidant is selected from at least one of hydrogen peroxide, urea peroxide, performic acid, peracetic acid, persulfate, percarbonate, periodic acid, perchloric acid, perboric acid, potassium permanganate and ferric nitrate.

10. An application of a chemical mechanical polishing slurry, characterized in that: For chemical mechanical polishing of copper.

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