Chemical mechanical polishing liquid and chemical mechanical polishing method

Abstract

The present invention provides a chemical mechanical polishing liquid and a chemical mechanical polishing method, wherein the chemical mechanical polishing liquid comprises an abrasive, an oxidant, a complexing agent, a corrosion inhibitor, a surfactant and water; wherein the surfactant comprises any one of fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyvinyl pyrrolidone, octaphenyl polyoxyacetylene or Tween-80 or a combination of at least two thereof. The present invention adds a suitable surfactant to the polishing liquid, which can improve the dispersion stability of the polishing liquid, make the surfactant adsorb on the surface of the abrasive grains, thereby changing the surface properties of the abrasive, effectively removing organic residues and particle contamination during the polishing process, and providing a better polishing basis for the second step of fine polishing, thereby preventing the residue after rough polishing from damaging the wafer during the fine polishing process.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer production, and in particular relates to a chemical mechanical polishing liquid and a chemical mechanical polishing method. Background Art

[0002] The integrated circuit industry is the core of the information technology industry and plays a key role in promoting the transformation and upgrading of the manufacturing industry to digitalization and intelligence. Chips are the carriers of integrated circuits. Chip manufacturing involves chip design, wafer manufacturing, wafer processing, electrical measurement, cutting packaging and testing. Among them, chemical mechanical polishing (CMP) is one of the five core processes in the wafer manufacturing process. Chemical mechanical polishing is an ultra-precision surface processing technology for global flattening. The whole process is an alternation of chemical and mechanical actions, and finally the polishing of the wafer surface is completed.

[0003] In the back-end process of integrated circuit manufacturing, the main purpose of CMP process for Co interconnect structure is to remove excess cobalt film and the barrier layer under the cobalt film while ensuring global planarization, so as to achieve complete insulation between Co interconnect wiring. Polishing of barrier layer, as the last CMP process of cobalt interconnect structure, plays a decisive influence on the final global planarization effect of wafer.

[0004] Cobalt has low resistivity, excellent adhesion properties and seamless filling capabilities without voids, and is considered by the industry to be the most promising candidate to replace traditional copper contact plugs in the middle of the line and copper interconnect wiring metals at the back end of the line. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present invention provides a chemical mechanical polishing liquid and a chemical mechanical polishing method.

[0006] In a first aspect, an embodiment of the present invention provides a chemical mechanical polishing solution, wherein the chemical mechanical polishing solution includes an abrasive, an oxidant, a complexing agent, a corrosion inhibitor, a surfactant and water;

[0007] Wherein, the surfactant includes any one of fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyvinyl pyrrolidone, octaphenyl polyoxyethylene or Tween-80, or a combination of at least two thereof.

[0008] In some embodiments, the surfactant is nonylphenol ethoxylate.

[0009] In some embodiments, the concentration of the surfactant is 500-1500 ppm.

[0010] In some embodiments, the surfactant is a compound surfactant consisting of nonylphenol polyoxyethylene ether and polyvinyl pyrrolidone.

[0011] In some embodiments, the concentration ratio of the nonylphenol polyoxyethylene ether to the polyvinyl pyrrolidone is 1:(1-3).

[0012] In some embodiments, the oxidant includes any one of hydrogen peroxide, peracetic acid, potassium persulfate, or ammonium persulfate, or a combination of at least two thereof.

[0013] In some embodiments, the complexing agent includes any one of citric acid, glycine, or ethylenediaminetetraacetic acid, or a combination of at least two thereof.

[0014] In some embodiments, the corrosion inhibitor includes any one of 1,2,4-triazole, potassium oleate, or 1-phenyl-5-mercaptotetrazole, or a combination of at least two thereof.

[0015] In some embodiments, the pH value of the polishing liquid is 9.5-11.

[0016] In a second aspect, an embodiment of the present invention provides a chemical mechanical polishing method, the chemical mechanical polishing method comprising:

[0017] The polishing liquid is spread on the surface of the polishing pad, the carrier head presses the wafer onto the polishing pad and drives the wafer to rotate, and the cobalt interconnect wafer structure is chemically mechanically polished under the action of the polishing liquid.

[0018] Compared with the prior art, the beneficial effects of the present invention include:

[0019] The present invention adds a suitable surfactant to the polishing liquid, which can improve the dispersion stability of the polishing liquid, make the surfactant adsorbed on the surface of the abrasive particles, thereby changing the surface properties of the abrasives, enhancing the repulsion between the abrasives, meeting the requirement of reducing the new surface energy and facilitating cleaning after adsorption, and at the same time promoting mass transfer between reaction products, which can effectively remove organic residues and particle pollution in the polishing process, and provide a better polishing basis for the second step of fine polishing, thereby preventing the residues after rough polishing from damaging the wafer during the fine polishing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The advantages of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings, which are only schematic and do not limit the scope of protection of the present invention, wherein:

[0021] Figure 1 The topographic scan diagram of the polished wafer surface provided by Embodiments 1-5 of the present invention is shown;

[0022] in, Figure 1(a) is a topographic scan of the surface of a polished wafer provided in Example 1 of the present invention;

[0023] Figure 1 (b) is a topographic scan of the wafer surface after polishing provided in Example 2 of the present invention;

[0024] Figure 1 (c) is a topographic scan of the wafer surface after polishing provided in Example 3 of the present invention;

[0025] Figure 1 (d) is a topographic scan of the wafer surface after polishing provided in Example 4 of the present invention;

[0026] Figure 1 (e) is a topographic scan of the wafer surface after polishing provided in Example 5 of the present invention;

[0027] Figure 2 The topographic scan diagram of the polished wafer surface provided by Embodiments 6-9 of the present invention is shown;

[0028] in, Figure 2 (a) is a topographic scan of the wafer surface after polishing provided in Example 6 of the present invention;

[0029] Figure 2 (b) is a topographic scan of the wafer surface after polishing provided in Example 7 of the present invention;

[0030] Figure 2 (c) is a topographic scan of the wafer surface after polishing provided in Example 8 of the present invention;

[0031] Figure 2 (d) is a topographic scan of the wafer surface after polishing provided in Example 9 of the present invention;

[0032] Figure 3 Shows a topographic scan of a polished wafer surface provided by Embodiments 10-13 of the present invention;

[0033] in, Figure 3 (a) is a topographic scan of a wafer surface after polishing provided in Example 10 of the present invention;

[0034] Figure 3 (b) is a topographic scan of the polished wafer surface provided in Example 11 of the present invention;

[0035] Figure 3 (c) is a topographic scan of the polished wafer surface provided in Example 12 of the present invention;

[0036] Figure 3 (d) is a topographic scan of the wafer surface after polishing provided in Example 13 of the present invention. DETAILED DESCRIPTION

[0037] The technical scheme of the present invention is described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments recorded herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limitations on the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments recorded herein.

[0038] "Composition" and like terms refer to a blend of two or more materials, which may or may not be miscible. Such a blend may or may not phase separate.

[0039] The numerical range in the present invention is an approximate value, so unless otherwise specified, it may include values ​​outside the range. The numerical range includes an infinite number of point values ​​within the range from the lower limit to the upper limit in increments of one unit, provided that there are at least two unit separations between any lower limit and any upper limit. The numerical range provided by the present invention, such as 100-1000, means point values ​​of all unit intervals, such as 100, 101, 102, ..., 999, 1000, etc., and sub-ranges within this numerical range, such as 100-144, 155-170, 197-200, etc. The above is only an example of specific intent, and all possible numerical combinations between the listed lower limit and upper limit should be regarded as the disclosed range and protection range clearly stated in the present invention.

[0040] The terms "comprising", "including", "having" and the like mean that the composition, process, etc. are not limited to the disclosed components, steps, etc., and may also include other undisclosed components, steps, etc., while the terms "consisting of...", "being" and the like indicate that only the specified components and steps are included, and other components and steps are excluded from the scope of the specified composition, process, etc.

[0041] Polishing fluid is one of the key elements in CMP technology. Its composition and performance are directly related to the material removal rate and the surface quality after polishing. In the material removal process of metal polishing, the polishing fluid has the following functions: the chelating agent reacts with the surface of the metal wafer to reduce the surface hardness or weaken the bonding strength of the metal, thereby increasing the metal removal rate; the corrosion inhibitor forms a chelate on the metal surface to passivate the metal recesses and prevent excessive corrosion. The abrasive in the polishing fluid often uses nanoparticles such as silicon dioxide or cerium dioxide, which have a small particle size and have quantum size effects and surface effects, so the particles are very easy to agglomerate. How to inhibit the agglomeration of abrasive particles is the key to preparing high-quality polishing fluid.

[0042] At least to solve the above technical problems, this embodiment provides a chemical mechanical polishing liquid, including an abrasive, an oxidant, a complexing agent, a corrosion inhibitor, a surfactant and water;

[0043] The surfactant includes any one of fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyvinyl pyrrolidone, octaphenyl polyoxyethylene or Tween-80, or a combination of at least two thereof.

[0044] The dispersion of abrasive particles in an aqueous medium is a process of dispersion and flocculation balance. Although physical methods such as ultrasonic vibration and mechanical stirring can achieve good dispersion of abrasive particles in an aqueous medium, when the external action stops, the abrasive particles will re-aggregate with each other. The chemical dispersion method, that is, adding surfactants to the polishing base liquid to make them adsorb on the surface of abrasive particles, can change the surface properties of abrasive particles, thereby continuously inhibiting the flocculation and aggregation of abrasive particles in an aqueous medium.

[0045] The surfactant used in this embodiment is composed of a hydrophilic group and a lipophilic group. The hydrophilic group is adsorbed on the surface of the abrasive particles, and the lipophilic group extends to the aqueous medium, thereby changing the surface charge distribution of the abrasive particles, and utilizing the electrostatic stabilization and steric stabilization between the abrasive particles to achieve a dispersion effect. This embodiment selects five surfactants suitable for Co from a large number of optional surfactants according to the types of functional groups they contain, namely, fatty alcohol polyoxyethylene ether (AEO, C 30 H 62 O 10 ), nonylphenol polyoxyethylene ether (NP, C 19 H 32 O3), polyvinylpyrrolidone (PVP, (C6H9NO) n ), octaphenyl polyoxyacetylene (OP-10, C 18 H 30 O3) or Tween-80 (T-80, C 24 H 44 O6(C2H4O) n ). The surfactants defined above all contain one or more functional groups, wherein AEO has a high ether bond (-COC-) content and a hydroxyl group (-OH), NP has -OC-, -OH and a benzene ring, OP-10 includes -COC, -OH and a benzene ring, T-80 has an ester bond (-COO-) and -OH, respectively, and PVP has a carbonyl group (-CO-). The material removal rate (MRR) of Co is directly related to the functional group of each surfactant, wherein the combination of -COC- and -OH can inhibit or not promote the removal rate to a certain extent, thereby obtaining a lower MRR. Based on this, the five surfactants defined above are particularly preferred in this embodiment.

[0046] In this embodiment, a suitable surfactant is added to the polishing liquid, which can improve the dispersion stability of the polishing liquid and make the surfactant adsorbed on the surface of the abrasive particles, thereby changing the surface properties of the abrasives and enhancing the repulsion between the abrasives. The requirement of reducing the energy of the new surface is met and it is easy to clean after adsorption. At the same time, it promotes the mass transfer between the reaction products, and can effectively remove organic residues and particle pollution in the polishing process. It also provides a better polishing foundation for the second step of fine polishing, preventing the residues after rough polishing from damaging the wafer during the fine polishing process.

[0047] Optionally, the surfactant is nonylphenol polyoxyethylene ether.

[0048] In this embodiment, nonylphenol polyoxyethylene ether (NP) is particularly preferred among the five surfactants. NP can significantly reduce the surface tension of the polishing liquid without significantly affecting the viscosity of the polishing liquid system or changing the fluidity of the polishing liquid system. At the same time, it can exert its dispersion, suspension, penetration and defoaming effects, effectively control the particle size distribution of abrasive particles in the polishing liquid, and maintain the stability of the polishing liquid system.

[0049] Optionally, the concentration of the surfactant is 500-1500 ppm, for example, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm or 1500 ppm.

[0050] When the concentration of the surfactant is low, the micelles formed by the surfactant are small, and the hydrophobic groups of the macromolecular organic matter cannot be coated, which will affect the dispersion effect of the abrasive particles in the polishing liquid and cause the abrasive particles to agglomerate. As the concentration of the surfactant increases, the micelles fully coat the hydrophobic groups, improve the dispersibility of the polishing liquid, and help achieve good polishing and cleaning effects. If the concentration of the surfactant is too high, the viscosity of the polishing liquid will be too high, affecting the fluidity of the polishing liquid, so that it cannot be evenly distributed on the polishing pad. At the same time, the polishing product cannot be separated from the surface of the polishing sheet in time, affecting the polishing rate and flattening effect, and may also cause scratches. Therefore, on the basis of balancing the viscosity of the polishing liquid and the dispersibility of the abrasive particles, this embodiment particularly prefers a surfactant concentration of 500-1500ppm, within which the fluidity of the polishing liquid and the dispersibility of the abrasive particles can be taken into account.

[0051] Optionally, the surfactant is a composite surfactant consisting of nonylphenol polyoxyethylene ether and polyvinyl pyrrolidone.

[0052] The present embodiment preferably uses NP and PVP to form a compound surfactant. When NP and PVP are mixed and compounded, the dispersion stability of the polishing liquid is significantly higher than the dispersion effect of a single surfactant. The addition of NP can enhance the lubrication and spreading effect of the polishing liquid, disperse the abrasive particles in the polishing liquid, increase the number of effective abrasive particles, and will not affect the viscosity of the polishing liquid, ensuring that the polishing liquid has sufficient fluidity, but will cause the contaminated particles generated by polishing to be deposited on the wafer surface again. PVP can solve this problem very well. Since PVP is a long-chain macromolecular surfactant, it can lift the contaminated particles generated by polishing during the polishing process to separate them from the wafer and be removed as the polishing liquid flows. Therefore, under the synergistic effect of NP and PVP, it can be ensured that the polishing liquid has high fluidity, the abrasive particles have high dispersibility in the polishing liquid, and the contaminated particles on the surface of the wafer after polishing are not only few but also not easy to deposit, and finally achieve an ideal polishing effect. In addition, after NP and PVP are compounded, the contact angle between the polishing liquid and the wafer interface becomes smaller, and the effect of the change in contact angle on the removal rate is not obvious, while a smaller contact angle will improve the subsequent cleaning effect on the wafer surface.

[0053] Optionally, the concentration ratio of nonylphenol polyoxyethylene ether to polyvinyl pyrrolidone is 1:(1-3), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2.0, 1:2.2, 1:2.4, 1:2.6, 1:2.8 or 1:3.0.

[0054] The polishing liquid composed of a single surfactant cannot further improve the surface quality of the polished wafer. In this embodiment, NP and PVP are compounded. Compared with a single surfactant, the compounded surfactant has a great positive effect on the surface quality of the polished wafer, which greatly reduces the number of surface particles of the polished wafer. On this basis, this embodiment limits the compounding ratio between NP and PVP to 1: (1-3). The reason is that NP has the characteristic of stabilizing foam. When the concentration of NP is relatively increased, the foam height in the polishing liquid increases and is difficult to eliminate; conversely, when the concentration of NP is relatively reduced, the viscosity of the polishing liquid will also increase due to the increase in the relative concentration of PVP, thereby affecting the fluidity of the polishing liquid. In addition, too much PVP will cover the surface of Co, which will reduce the chemical action of the oxidant and the complexing agent on Co, affecting the removal rate of Co. By controlling the ratio of different surfactants, the polishing rate can be controlled.

[0055] Optionally, the oxidant includes any one of hydrogen peroxide, peracetic acid, potassium persulfate or ammonium persulfate, or a combination of at least two thereof.

[0056] Optionally, the complexing agent includes any one of citric acid, glycine or ethylenediaminetetraacetic acid, or a combination of at least two thereof.

[0057] During the CMP process of metals, due to the presence of oxidants in the polishing liquid, a layer of oxide film with passivation properties often forms on the metal surface. This passivation film covers the metal surface, which hinders the further removal of the material to a certain extent. At the same time, the passivation film is removed under the mechanical grinding action of the abrasive and the polishing pad, and becomes an insoluble substance remaining in the polishing liquid. If it is not dissolved in time and carried away by the polishing liquid, it will contaminate the wafer surface and cause scratches and other damage. Therefore, an appropriate amount of complexing agent needs to be added to the polishing liquid. The reason is that the complexing agent will react with metal oxides or metal ions to form a soluble metal organic complex: it can effectively prevent the insoluble substances generated by the passivation film from polluting and damaging the surface, and can also reduce the metal ion pollution in the polishing liquid. At the same time, it also promotes the removal rate of metal materials, and improves the overall polishing efficiency of the CMP process to a certain extent.

[0058] Optionally, the corrosion inhibitor includes any one of 1,2,4-triazole, potassium oleate or 1-phenyl-5-mercaptotetrazole, or a combination of at least two thereof.

[0059] During the CMP process of metal, since the corrosion on its surface is isotropic, that is, both the convex and concave parts of the metal surface will be corroded by various additives in the polishing liquid, it is easy to cause defects such as surface roughness, dishing and corrosion pits. Therefore, corrosion inhibitors must be added to the polishing liquid to reduce surface corrosion and improve the quality of metal surface flatness.

[0060] It should be noted that this embodiment provides a variety of optional oxidants, complexing agents and corrosion inhibitors, which can be arbitrarily combined to form polishing liquids of different components, for example, a combination of hydrogen peroxide, citric acid and 1,2,4-triazole, a combination of peracetic acid, glycine and potassium oleate, a combination of potassium persulfate, ethylenediaminetetraacetic acid, ammonium persulfate, 1-phenyl-5-mercaptotetrazole, a combination of potassium persulfate, citric acid and potassium oleate, etc. The specific combinations listed above and the combinations that are not listed and can form a stable mixture all belong to the protection scope and disclosure scope of this embodiment.

[0061] It should be noted that, in this embodiment, the abrasive is preferably colloidal silica, and the colloidal silica is preferably prepared by hydrolyzing alkoxysilane, and this preparation method can obtain silica particles without impurities. In addition, it can also be prepared by eliminating the alkali metal in the alkali metal silicate aqueous solution, but this preparation method will cause the alkali metal remaining in the particles to be gradually washed out, thereby adversely affecting the polishing performance.

[0062] The diameter of the silica particles in the colloidal silica can be appropriately selected according to the intended application of the abrasive grains, and is generally in the range of about 10 nm to 200 nm. In one embodiment, the diameter of the silica particles is 40 to 80 nm, preferably 60 nm.

[0063] Optionally, the pH value of the polishing liquid is 9.5-11, for example, it can be 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9 or 11.

[0064] The polishing liquid provided in this embodiment should have a pH value in the range of 9.5-11, and preferably in the range of 10-10.5. In order to adjust the pH value within the above required range, a base can be used as a pH adjuster.

[0065] It should be noted that the present embodiment does not make any specific requirements or special restrictions on the type of base, and it may be, for example, ammonia, organic ammonium hydroxide (such as ammonium hydroxide and tetramethylammonium hydroxide), non-metallic alkaline reagents (such as diethanolamine, triethanolamine and triisopropanolamine) or alkali metal hydroxides (such as potassium hydroxide and lithium hydroxide, etc.). Among the various bases listed above, ammonium hydroxide, potassium hydroxide, lithium hydroxide or tetramethylammonium hydroxide is preferably used.

[0066] It should be noted that this embodiment does not make any specific requirements or special limitations on the amount of pH adjuster added. The pH value of the final polishing liquid is within the range of 9.5-11. The amount of pH adjuster added can be determined to be any amount that maintains the pH value within the required range.

[0067] This embodiment does not make specific requirements and special restrictions on the preparation method of the polishing liquid. The screened abrasive, oxidant, complexing agent and corrosion inhibitor can be dissolved or dispersed in an aqueous medium, especially deionized water. For this purpose, conventional and standard mixing methods and mixing equipment can be used, such as a stirred tank, an online dissolver, a high-shear high-speed mixer, an ultrasonic mixer, a homogenizer nozzle or a convection mixer. The mixed liquid is filtered through a filter with appropriate mesh to remove coarse granular particles, and finally the polishing liquid for chemical mechanical polishing provided in this embodiment is obtained.

[0068] In another specific embodiment, this embodiment provides a chemical mechanical polishing method, comprising:

[0069] Polishing liquid is spread on the surface of the polishing pad, and the carrier head presses the wafer onto the polishing pad and drives the wafer to rotate. Under the action of the polishing liquid, the cobalt interconnect wafer structure is chemically mechanically polished.

[0070] Examples 1-5

[0071] Silica sol abrasive, oxidant potassium persulfate (KPS), complexing agent citric acid (CA), corrosion inhibitor 1,2,4-triazole (TAZ) and different types of surfactants were weighed / measured respectively, and mixed according to the distribution ratio of each component provided in Table 1 to obtain the corresponding polishing solution.

[0072] Table 1

[0073]

[0074]

[0075] The chemical mechanical polishing liquid provided in Examples 1-5 was used to perform chemical mechanical polishing on a 12-inch Co wafer, and the surface morphology of the wafer after polishing was scanned to obtain the following: Figure 1 The topographic scan shown in the figure summarizes the number of particles on the wafer surface and the data is shown in Table 2.

[0076] Table 2

[0077] Example Number of particles (particles / piece) Example 1 2623 Example 2 3292 Example 3 4502 Example 4 6148 Example 5 3318

[0078] Depend on Figure 1 It can be seen from the topographic scanning map provided and the number of particles on the wafer surface provided in Table 2 that the number of particles after polishing the Co wafer using the polishing liquid provided in Example 1 is the least and the surface quality is the highest. This is because NP can greatly reduce the surface tension of the polishing liquid without significantly affecting the viscosity of the polishing liquid system or changing the fluidity of the polishing liquid system; while the other four polishing liquids will increase the viscosity of the polishing liquid to a certain extent, resulting in poor fluidity of the polishing liquid during dispersion.

[0079] Embodiment 6-9

[0080] Silica sol abrasive, oxidant potassium persulfate (KPS), complexing agent citric acid (CA) and corrosion inhibitor 1,2,4-triazole (TAZ) were weighed / measured respectively as the polishing liquid base liquid, and the base liquid and the compound surfactant (NP and other component surfactants) were mixed according to the component ratios provided in Table 3 to obtain the corresponding polishing liquid.

[0081] Table 3

[0082]

[0083]

[0084] The chemical mechanical polishing liquid provided in Example 6-9 was used to perform chemical mechanical polishing on a 12-inch Co wafer, and the surface morphology of the wafer after polishing was scanned to obtain the following: Figure 2 The topographic scan shown in the figure summarizes the number of particles on the wafer surface and the data is shown in Table 4.

[0085] Table 4

[0086] Example Number of particles (particles / piece) Example 6 175 Example 7 369 Example 8 374 Example 9 313

[0087] Depend on Figure 2 It can be seen from the topographic scanning map provided and the number of particles on the wafer surface provided in Table 4 that the number of particles after polishing the Co wafer using the polishing liquid (PVP and NP compound) provided in Example 6 is the least and the surface quality is the highest. This is because NP does not affect the fluidity of the polishing liquid, allowing the polishing liquid to flow normally, and PVP can lift the contaminated particles to separate them from the wafer surface and remove them as the polishing liquid flows. The two work together to remove the contaminated particles. The other combinations of compound surfactants significantly increase the number of particles due to reasons such as the polishing liquid viscosity being too high to flow or the contaminated particles being deposited.

[0088] Examples 10-13

[0089] Silica sol abrasive, oxidant potassium persulfate (KPS), complexing agent citric acid (CA) and corrosion inhibitor 1,2,4-triazole (TAZ) were weighed / measured respectively, and mixed according to the proportions of each component provided in Table 5 to obtain the corresponding polishing solution.

[0090] Table 5

[0091]

[0092]

[0093] The chemical mechanical polishing liquid provided in Examples 11-15 was used to perform chemical mechanical polishing on a 12-inch Co wafer, and the surface morphology of the wafer after polishing was scanned to obtain the following: Figure 3 The topographic scan shown in the figure summarizes the number of particles on the wafer surface and the data is shown in Table 6.

[0094] Table 6

[0095] Example Number of particles (particles / piece) Example 10 284 Example 6 175 Embodiment 11 64 Example 12 77 Embodiment 13 276

[0096] Depend on Figure 3 It can be seen from the topographic scanning map provided and the number of particles on the wafer surface provided in Table 6 that the number of particles after polishing the Co wafer using the polishing liquid provided in Example 6, Example 11 and Example 12 is the least, and the surface quality is the highest. Compared with Example 6, the PVP concentration in the compound surfactant used in Example 10 is too low, and the number of particles on the surface of the wafer after polishing increases significantly. Compared with Example 12, the PVP concentration in the compound surfactant used in Example 13 is too high, and the number of particles on the surface of the wafer after polishing also increases significantly.

[0097] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A chemical mechanical polishing solution for rough polishing of cobalt interconnect wafer structures, characterized in that: The chemical mechanical polishing liquid is composed of abrasive, oxidant, complexing agent, corrosion inhibitor, surfactant and water; in, The abrasive is colloidal silica prepared by hydrolyzing alkoxysilane, wherein the diameter of the silica particles is 10nm-200nm; The oxidant includes any one of hydrogen peroxide, peracetic acid, potassium persulfate or ammonium persulfate or a combination of at least two thereof; the complexing agent includes any one of citric acid, glycine or ethylenediaminetetraacetic acid or a combination of at least two thereof; the corrosion inhibitor includes any one of 1,2,4-triazole, potassium oleate or 1-phenyl-5-mercaptotetrazole or a combination of at least two thereof; and the pH value of the polishing liquid is 9.5-11; The surfactant consists of nonylphenol polyoxyethylene ether and polyvinyl pyrrolidone, the concentration of the surfactant is 500-1500ppm, and the concentration ratio of the nonylphenol polyoxyethylene ether to the polyvinyl pyrrolidone is 1:(1-3).

2. A chemical mechanical polishing method, characterized in that: The chemical mechanical polishing method comprises: The polishing liquid of claim 1 is spread on the surface of the polishing pad, the carrier head presses the wafer onto the polishing pad and drives the wafer to rotate, and the cobalt interconnect wafer structure is chemically mechanically polished under the action of the polishing liquid.

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