Chemical mechanical polishing solution as well as preparation method and application thereof

Abstract

The invention relates to the technical field of grinding and polishing, in particular to a chemical mechanical polishing solution as well as a preparation method and application thereof. The chemical mechanical polishing solution is prepared from the following components in percentage by mass: 5 to 7 weight percent of silica sol, 0.1 to 1 weight percent of surfactant, 0.1 to 1 weight percent of complexing agent, 0.01 to 1 weight percent of corrosion inhibitor, 0.02 to 2 weight percent of additive and the balance of pH (Potential of Hydrogen) regulator and water, and the surface active agent is a silane coupling agent A-1170. The chemical mechanical polishing solution provided by the invention realizes selective specificity of a copper layer and an oxide layer under low abrasive concentration, can selectively remove the oxide layer while polishing the copper layer, and has good industrialization value.

Description

Technical Field

[0001] This invention relates to the field of grinding and polishing technology, and in particular to a chemical mechanical polishing fluid, its preparation method, and its application. Background Technology

[0002] Chemical mechanical polishing (CMP) is an ultra-precision surface finishing technology that combines chemical etching with mechanical grinding. It is currently the only technology in integrated circuit manufacturing capable of achieving global surface planarization. Polishing slurry is a core consumable in the CMP process. Its typical formulation is a water-soluble polishing agent free of harmful additives such as sulfur, phosphorus, and chlorine. It must simultaneously possess excellent degreasing, rust prevention, cleaning, and brightening properties, and be able to impart the intrinsic luster to the metal surface after polishing.

[0003] In the copper interconnect process of integrated circuits, an oxide layer (such as SiO2 or low-k material) is deposited on the substrate layer, followed by etching of conductive trenches and vias in the oxide layer. A barrier layer (such as Ta / TaN) is then deposited within the trenches and vias. Copper is then filled into the trenches and vias covered by the barrier layer until they are full and overflow. Finally, excess copper and the barrier layer outside the trenches are removed using a CMP process, retaining only the functional structures within the trenches. This CMP typically consists of three steps: 1) coarse polishing: using high pressure to remove a large amount of copper; 2) fine polishing (endpoint detection): reducing the polishing pressure, removing residual copper from the wafer surface and stopping at the barrier layer; 3) barrier layer polishing: using a polishing slurry to polish the barrier layer. During step 2) in the process of removing residual copper, dish-shaped depressions may form on the wafer surface. To address this, a polishing slurry with a specific copper, barrier layer, and oxide layer removal rate selectivity ratio is typically used in step 3) to repair the dish-shaped depressions.

[0004] Traditional polishing slurries typically require high abrasive concentrations (>10%) to achieve high removal rates, but high abrasive concentrations can lead to increased surface scratches and more defects after polishing. Although some studies have explored high removal rates at low abrasive concentrations through formulation optimization, these studies primarily focus on alkaline systems. For example, CN 116515397 A discloses a chemical mechanical polishing slurry for barrier layer planarization, comprising abrasive particles, azole compounds, complexing agents, oxidants, water-soluble cellulose, nonionic surfactants, and water. This polishing slurry has a concentration of 2-10% and a pH of 8-12. While the addition of hydroxyethyl cellulose and fatty alcohol polyoxyethylene ether can alleviate dish-shaped depressions, its oxide layer removal rate is relatively low (599-722 A / min), and the alkaline conditions themselves pose a risk of equipment corrosion, limiting its applicable process window. CN110205035B discloses an additive and its application and usage method. The additive includes 0.5-5% hydroxyethylidene diphosphate, 0.5-2% benzotriazole, 0.1-0.5% polyacrylamide, 0.01-0.2% defoamer, and deionized water to make up the balance. Based on acid polishing process, adding this additive to the traditional acid polishing solution can significantly improve the surface reflectivity. The addition of sulfuric acid, hydrofluoric acid, and nitric acid to the polishing solution also significantly reduces the amount used, thus greatly reducing costs. This patent uses benzotriazole as a corrosion inhibitor. Benzotriazole (BTA) is currently the most widely used inhibitor. During CMP, BTA forms an adsorption film on the Cu surface, providing the expected protection against various forms of corrosion. The form of BTA is related to the pH value of the polishing solution. However, due to the strong adhesion of the Cu-BTA film, it is difficult to remove during CMP cleaning, resulting in organic residues and particulate contaminants on the Cu surface.

[0005] In summary, the disadvantages of existing technologies are: 1) Traditional acidic polishing slurries require high abrasive concentrations to achieve high removal rates, but high abrasive concentrations lead to increased surface scratches. 2) Equipment corrosion issues: Alkaline polishing slurries are highly corrosive to polishing equipment such as stainless steel, increasing equipment maintenance costs. 3) Difficulty in controlling polishing selectivity: Although alkaline polishing slurries have a high copper removal rate, they may result in insufficient precision in controlling the polishing selectivity ratio among copper, oxide layers, and barrier layers, making it difficult to simultaneously meet the synergistic requirements of high barrier layer removal rate, moderate oxide layer repair capability, and extremely low copper loss at low abrasive concentrations.

[0006] Therefore, there is an urgent need for a chemical mechanical polishing slurry that can selectively and specifically polish copper and oxide layers at low abrasive concentrations, achieving low copper layer loss while effectively removing oxide layers. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a chemical mechanical polishing (CMP) slurry, its preparation method, and its application. The CMP slurry of this invention solves the problems of high concentration, the need for polishing under alkaline conditions leading to equipment corrosion, and poor selectivity for copper and oxide layers in existing CMP slurries.

[0008] To achieve the above and other related objectives, the present invention is obtained through the following technical solution.

[0009] The first aspect of the present invention discloses a chemical mechanical polishing slurry comprising the following components by mass fraction: 5-7 wt% silica sol, 0.1-1 wt% surfactant, 0.1-1 wt% complexing agent, 0.01-1 wt% corrosion inhibitor, 0.02-2 wt% additive, with the balance being a pH adjuster and water; wherein the surfactant is silane coupling agent A-1170.

[0010] The applicant conducted multiple screenings of surfactants and accidentally discovered that silane coupling agent A-1170 can be used as a surfactant in chemical mechanical polishing slurries. Furthermore, the chemical mechanical polishing slurry formed by combining it with a complexing agent can regulate the polishing selectivity of the chemical mechanical polishing slurry for copper layers and oxide layers (SiO2), thereby achieving the synergistic requirement of simultaneously polishing copper layers and selectively removing oxide layers at low silica sol concentrations.

[0011] In some embodiments, the mass fraction of the silica sol may be 5-7 wt%, or 5 wt%, 6 wt%, or 7 wt%. In this invention, the silica sol acts as an abrasive to perform grinding, thereby improving the polishing rate.

[0012] In some embodiments, the particle size of the silica sol can be 65-75 nm, 65-71 nm, 70-75 nm, or 65 nm, 66 nm, 67 nm, 68 nm, 69 nm, 70 nm, 71 nm, 72, 73 nm, 74 nm, and 75 nm. If the silica sol particle size of the present invention is less than 65 nm, the polishing efficiency and effect decrease; if the particle size is greater than 75 nm, unacceptable scratches are easily generated on the surface, affecting the surface quality.

[0013] In some embodiments, the mass fraction of the surfactant may be 0.1-1 wt%, 0.1-0.5 wt%, 0.4-1 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%.

[0014] In some embodiments, the mass fraction of the complexing agent may be 0.1-1 wt%, 0.1-0.5 wt%, 0.4-1 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%.

[0015] In some embodiments, the complexing agent is selected from one or more of the following: hydroxyethylidene diphosphate, sodium ethylenediaminetetramethyleneide phosphonate, diethylenetriaminepentamethyleneide phosphonate, diethylenetriaminepentacarboxylate, hydrolyzed polymaleic anhydride, polyacrylic acid, polyhydroxyacrylic acid, maleic acid-acrylic acid copolymer, polyacrylamide, ethylenediaminetetraacetic acid, polyaspartate, glutamic acid diacetate, methylglycine diacetate, and aspartic acid diacetate. In this invention, the copper layer surface is first oxidized to Cu₂O and CuO under the action of the oxidant; Cu₂O is further oxidized to CuO; CuO can further react with H₂O to generate Cu(OH)₂; Cu(OH)₂ exists in a weak ionization equilibrium and can release Cu… 2+ Complexing agent and Cu 2+ A complexation reaction occurs to form a complex that is easily removed by mechanical action.

[0016] In some embodiments, the corrosion inhibitor may be 0.01-0.5 wt%, 0.3-0.8 wt%, 0.5-1 wt%, or 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%.

[0017] In some embodiments, the corrosion inhibitor is selected from one or more of 5-aminotetrazole, benzotriazole, methylbenzotriazole, imidazole, benzimidazole, and 2-mercaptobenzimidazole.

[0018] In some embodiments, the additive may also be 0.02-0.9 wt%, 0.8-1.5 wt%, 1.4-2 wt%, or 0.02 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, or 2 wt%.

[0019] In some embodiments, the additive includes 0.01-1 wt% of an oxidant and / or 0.01-1 wt% of a bactericide.

[0020] In some specific embodiments, the oxidant may also be 0.01-0.5 wt%, 0.3-0.8 wt%, 0.5-1 wt%, or 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%.

[0021] In some specific embodiments, the oxidant is selected from one or more of hydrogen peroxide, peracetic acid, and ammonium persulfate.

[0022] In some specific embodiments, the bactericide may be 0.01-0.5 wt%, 0.3-0.8 wt%, 0.5-1 wt%, or 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%.

[0023] In some specific embodiments, the bactericide is selected from one or more of Kathon, benzisothiazolinone, and methylisothiazolinone.

[0024] In some embodiments, the mass ratio of the surfactant to the complexing agent is (1-6):1, or it can be (1-4):1, or it can be (3-6):1. Preferably, it is 3:1. This invention has found that as the mass ratio of the surfactant to the complexing agent increases, the polishing selectivity first increases and then decreases. When the mass ratio of the surfactant to the complexing agent is 3:1, the optimal polishing selectivity is 2.64, and the number of large particles (≥1μm) in the polishing solution is less than 15,000 particles / mL, and the number of large particles (≥0.5μm) is less than 150,000 particles / mL.

[0025] Preferably, the pH value of the chemical mechanical polishing solution is 2-5. For example, it can be 2-2.8, 2.5-3.2, 3-4.5, or 4.3-5. Within the pH range of this invention, the chemical mechanical polishing solution exhibits the best synergistic effect of mechanical polishing and chemical action on the oxide layer while minimizing damage to the copper layer. If the pH is below 2, the polishing rate of the copper layer will be too fast, and corrosion will easily occur. If the pH is above 5, the polishing rate of the copper layer will be reduced.

[0026] In some implementations, the polishing pressure is: 5 pis for the retaining ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; the polishing speed is... Under the conditions of rpm, polishing fluid flow rate of 300 ml / min, and temperature of 25℃, the polishing rate of the above polishing fluid on copper is 250~850 Å / min; including but not limited to 250 Å / min, 260 Å / min, 270 Å / min, 280 Å / min, 300 Å / min, 350 Å / min, 400 Å / min, 410 Å / min, 420 Å / min, 450 Å / min, 500 Å / min, 550 Å / min, 600 Å / min, 650 Å / min, 700 Å / min, 750 Å / min, 800 Å / min, and 850 Å / min.

[0027] In some implementations, the polishing pressure is: 5 pis for the retaining ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; the polishing speed is... Under the conditions of rpm, polishing slurry flow rate of 300 ml / min, and temperature of 25℃, the polishing rate of the above polishing slurry on silicon dioxide is 600~2200 Å / min; including but not limited to 600 Å / min, 650 Å / min, 700 Å / min, 740 Å / min, 760 Å / min, 780 Å / min, 800 Å / min, 850 Å / min, 900 Å / min, 950 Å / min, 1000 Å / min, 1100 Å / min, 1300 Å / min, 1500 Å / min, 1700 Å / min, 1800 Å / min, 2000 Å / min, and 2200 Å / min.

[0028] In some implementations, the polishing pressure is: 5 pis for the retaining ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; the polishing speed is... Under the conditions of rpm, polishing fluid flow rate of 300 ml / min, and temperature of 25℃, the polishing rate of the above polishing fluid on tantalum nitride is 380~550 Å / min; including but not limited to 380 Å / min, 400 Å / min, 410 Å / min, 420 Å / min, 430 Å / min, 440 Å / min, 450 Å / min, 460 Å / min, 470 Å / min, 480 Å / min, 490 Å / min, 500 Å / min, and 550 Å / min.

[0029] In some implementations, the polishing pressure is: 5 pis for the retaining ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; the polishing speed is... Under the conditions of rpm, polishing fluid flow rate of 300 ml / min, and temperature of 25℃, the polishing selectivity ratio of the above polishing fluid for silica / copper is 2.3~2.8; including but not limited to 2.3, 2.4, 2.5, 2.6, 2.7, and 2.8.

[0030] Where HS is the rotational speed of the polishing head per minute, and PS is the rotational speed of the polishing disc per minute.

[0031] Preferably, the number of large particles ≥0.5μm in each 1mL of polishing liquid is 110,000 to 220,000; for example, it can be 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, or 220,000.

[0032] Preferably, the number of large particles ≥1μm in each 1mL of polishing liquid is 10,000 to 40,000; for example, it can be 10,000, 20,000, 30,000, or 40,000 particles.

[0033] The second aspect of the present invention discloses a method for preparing the chemical mechanical polishing slurry as described above, comprising: mixing and filtering the components to obtain the chemical mechanical polishing slurry.

[0034] The preparation method of this invention does not restrict the mixing order of the components. For example, the corrosion inhibitor and water can be mixed, followed by the addition of a complexing agent, surfactant, and silica sol, and then a pH adjuster can be added to adjust the polishing solution to the desired pH value. Alternatively, the corrosion inhibitor, complexing agent, surfactant, and silica sol can be mixed, the pH adjusted to the desired value using a pH adjuster, and then a bactericide can be added. The oxidant of this invention can also be added during polishing.

[0035] In some implementations, the following steps are included:

[0036] 1) Water and corrosion inhibitor are mixed to obtain the first mixed solution;

[0037] 2) Add a complexing agent and a surfactant to the first mixed solution and mix to obtain a second mixed solution;

[0038] 3) Add silica sol to the second mixed solution and mix to obtain a third mixed solution;

[0039] 4) Add a pH adjuster to the third mixed solution and mix to obtain a fourth mixed solution;

[0040] 5) Add additives to the fourth mixed solution, and filter to obtain the chemical mechanical polishing slurry.

[0041] In some embodiments, the mixing method is stirring, and the stirring speed is 100-300 r / min. For example, the stirring speed can be 100, 110 r / min, 120 r / min, 130 r / min, 140 r / min, 150 r / min, 180 r / min, 220 r / min, 250 r / min, 280 r / min, or 300 r / min. The stirring speed in each step of this invention can be the same or different. Stirring is for better mixing, and those skilled in the art can adjust the stirring speed according to actual needs.

[0042] In some embodiments, the mixing time for adding silica sol is 45-75 min. For example, it can be 45-50 min, 50-55 min, 55-60 min, 60-65 min, 65-70 min, or 70-75 min.

[0043] In some embodiments, the mixing time for adding the pH adjuster is 45-75 min. For example, it can be 45-50 min, 50-55 min, 55-60 min, 60-65 min, 65-70 min, or 70-75 min. In this invention, the pH adjuster is added in step 4) to make the pH of the entire polishing solution more effective.

[0044] In some embodiments, the mixing time for adding the additive is 90-180 min. Examples include 90-100 min, 100-110 min, 110-120 min, 120-130 min, 130-140 min, 140-150 min, 150-160 min, 160-170 min, and 170-180 min. The bactericide in the additive of this invention is added in step 5) to effectively inhibit bacteria in the entire polishing solution. The oxidant can be added before polishing on the machine or in step 5), preferably before polishing on the machine to avoid decomposition of the oxidant.

[0045] In some implementations, the filtration includes primary filtration and secondary filtration.

[0046] In some embodiments, the primary filtration uses a 1μm filter element, and the secondary filtration uses a 0.5μm filter element.

[0047] The third aspect of the present invention also discloses the application of the chemical mechanical polishing slurry as described above in the planarization of copper layers.

[0048] The fourth aspect of the present invention also discloses the use of silane coupling agent A-1170 in improving the polishing selectivity of chemical mechanical polishing slurry for copper layers and oxide layers.

[0049] In this invention, the polishing selectivity ratio refers to the ratio of the polishing rate of the oxide layer to the polishing rate of the copper layer, wherein the oxide layer is a silicon dioxide layer.

[0050] In some embodiments, the polishing selectivity ratio is (2.3-2.8):1.

[0051] When the polishing selectivity ratio in this invention is greater than 2.8, it indicates that because the oxide layer is polished very quickly while the copper layer is polished very slowly, the oxide layer at higher elevations is rapidly flattened, or even over-removed. Meanwhile, the copper layer steps at higher elevations remain and cannot be effectively reduced. To remove these difficult-to-remove copper layers, the polishing time must be significantly extended. This not only reduces productivity but also introduces more defects due to prolonged mechanical friction, exacerbating the aforementioned dish-shaped depressions and erosion problems. When the polishing rate of the polishing slurry decreases for the copper layer but is too fast for the oxide layer, once the polishing penetrates the thin oxide layer, it will begin to rapidly erode other underlying media materials (such as ultra-low k materials), causing irreparable damage.

[0052] When the polishing selectivity ratio in this invention is below 2.3, it indicates that the copper layer removal rate is too fast, resulting in more severe dish-shaped pits and erosion. Because the copper layer is removed excessively and rapidly, a deep pit forms inside the copper trace. Simultaneously, because the adjacent oxide layer is removed too slowly, its top widens, leading to a more significant step height difference. This significantly increases the interconnect resistance (R) and inter-line capacitance (C), resulting in increased RC delay, slower chip speed, and higher power consumption.

[0053] Compared with the prior art, the chemical mechanical polishing fluid, its preparation method, and its application of the present invention have the following beneficial effects:

[0054] Through extensive screening of surfactants, this invention discovered that when the surfactant is silane coupling agent A-1170, the resulting chemical mechanical polishing slurry achieves good polishing selectivity for copper and oxide layers. The polishing rate for copper (Cu) layers is 250–850 Å / min, the polishing rate for oxide layers (formed from SiO2) is 600–2200 Å / min, and the polishing rate for barrier layers (TaN) is 380–550 Å / min. Furthermore, the polishing selectivity ratio between silica and copper layers is 2.3–2.8. In addition, the number of particles (≥1 μm) in the polishing slurry is less than 25,000 particles / mL, and the number of large particles (≥0.5 μm) is less than 200,000 particles / mL, ensuring good dispersibility and stability of the polishing slurry during use. Detailed Implementation

[0055] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0056] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0057] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0058] In the following embodiments of this application, the average particle size of the silica sol is 70 nm, and the content of silicon oxide is 30.5 wt%. The mass fraction of the silica sol described below refers to the mass fraction of solid silicon oxide in the entire polishing slurry. The molecular weight of the polyacrylamide is 8 million.

[0059] Examples 1-6

[0060] Examples 1-6 provide a chemical mechanical polishing slurry and its preparation method, with specific formulations shown in Table 1.

[0061] Table 1. Formula (%)

[0062]

[0063] The preparation method of chemical mechanical polishing slurry includes the following steps:

[0064] 1) Add corrosion inhibitor and water to a clean reactor according to the specified ratio and start stirring at 200 r / min;

[0065] 2) Add the complexing agent and surfactant according to the ratio, and continue stirring until they are completely dissolved;

[0066] 2) Then add silica sol, keep the speed constant, and stir for 1 hour;

[0067] 4) Stir well, and adjust the pH of the solution to 3 with nitric acid (pH adjuster); keep the speed constant and stir for 30 minutes.

[0068] 5) Add additives, keep the speed constant, and stir for 1 hour;

[0069] 6) The product is filled after passing through a primary filter (1μm filter cartridge) and a secondary filter (0.5μm filter cartridge) from a COBBAT filter cartridge.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 3 is that silane coupling agent KH550 is used instead of silane coupling agent A-1170, while the rest are the same as in Example 3. The specific formulation is shown in Table 1.

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 3 is that silane coupling agent KH560 is used instead of silane coupling agent A-1170, while the rest are the same as in Example 3. The specific formulation is shown in Table 1.

[0074] Comparative Example 3

[0075] The difference between Comparative Example 3 and Example 3 is that polyoxyethylene (20) stearate was used instead of silane coupling agent A-1170, while the rest were the same as in Example 3. The specific formulation is shown in Table 1.

[0076] Comparative Example 4

[0077] The difference between Comparative Example 4 and Example 3 is that sodium dodecylbenzenesulfonate is used instead of silane coupling agent A-1170; otherwise, they are the same as in Example 3. See Table 1 for the specific formulation.

[0078] Comparative Example 5

[0079] The difference between Comparative Example 5 and Example 3 is that Comparative Example 5 adds polyacrylamide with a final concentration of 0.2 wt% to the formulation of Example 3, while the rest are the same as in Example 3.

[0080] The chemical mechanical polishing slurries obtained in Examples 1-6 and Comparative Examples 1-5 were used to polish 12-inch Cu / SiO2 / TaN wafers: 3L of chemical mechanical polishing slurry was taken and diluted with pure water at a dilution ratio of 1:4.

[0081] Polishing machine: Huahai Qingke Universal-300E

[0082] Polishing pad: KC-100 (20*20mm groove):

[0083] Polishing pressure: 5 pis for retaining ring, 3 pis for Zone 1, and 2 pis for Zones 2-7.

[0084] Polishing speed: HS / PS = 93 / 87 rpm

[0085] Polishing fluid flow rate: 300 mL / min

[0086] Polishing temperature: 25℃

[0087] Polishing time: 60s.

[0088] The polishing effect of the chemical mechanical polishing slurry was tested, and the results are shown in Table 2 below.

[0089] The polishing rate is calculated by calculating the change in wafer film thickness before and after polishing and then dividing by the polishing time. The formula for film thickness is... T before T represents the film thickness before wafer polishing. after This represents the film thickness after wafer polishing.

[0090] Polishing selectivity = Polishing rate of oxide barrier layer / Polishing rate of Cu

[0091] Furthermore, the polishing solution was collected 7 days after filling and the number of large particles (in ten thousand) in the polishing solution was tested using an Entegris A7000 instrument to evaluate the dispersibility of the polishing solution. ≥0.5μm represents the total number of particles with a diameter ≥0.5μm per mL of polishing solution, and ≥1μm represents the total number of particles with a diameter ≥1μm per mL of polishing solution. The results of the large particle count test are shown in Table 2.

[0092] Table 2

[0093]

[0094] As shown in Table 2, the chemical mechanical polishing slurries prepared in Examples 1-4 have a polishing rate of 250-850 Å / min for copper layers, a polishing rate of 600-2200 Å / min for silicon dioxide layers, and a polishing rate of 380-550 Å / min for tantalum nitride layers. The polishing selectivity ratio between silicon dioxide and copper layers is 2.3-2.8. Under this polishing selectivity ratio, selective specificity for copper and oxide layers is achieved, realizing the polishing of copper layers while selectively removing oxide layers, which has good industrialization value.

[0095] As shown in Table 2, the chemical mechanical polishing slurry of the present invention exhibits selective specificity for copper and oxide layers, with a polishing selectivity ratio of 2.3-2.8 between the oxide and copper layers. Furthermore, the particle count (≥1μm) is less than 25,000 particles / mL, and the number of large particles (≥0.5μm) is less than 200,000 particles / mL. In contrast, the polishing slurries formed using silane coupling agent KH550 (Comparative Example 1), silane coupling agent KH560 (Comparative Example 2), polyoxyethylene (20) stearate (Comparative Example 3), and sodium dodecylbenzene sulfonate instead of silane coupling agent A-1170 (Comparative Example 4) have a polishing selectivity ratio between the oxide and copper layers >2.8. Moreover, the number of large particles (≥1μm) exceeds 30,000 particles / mL, and the number of large particles (≥0.5μm) exceeds 200,000 particles / mL. Subsequent polishing of the copper layer with these slurries will generate stronger mechanical friction, thereby accelerating the wear of the copper layer. In addition, it will also lead to defects such as scratches and pits on the copper layer surface.

[0096] As shown in Table 2, the addition of polyacrylamide to the polishing slurry of the present invention results in a significant decrease in the polishing rate of the copper layer and a polishing selectivity ratio > 4, which leads to the rapid thinning of the oxide layer and unevenness of the entire wafer.

[0097] As shown in Table 2, when the mass ratio of silane coupling agent A-1170 to hydroxyethylidene diphosphate in the polishing solution is 1:1 (i.e., Example 1) or 2:1 (i.e., Example 2), the polishing selectivity is 2.3 and 2.41, respectively. When the mass ratio of silane coupling agent A-1170 to hydroxyethylidene diphosphate is 4:1 (i.e., Example 4), the polishing rate of the copper layer and oxide layer decreases, and the polishing selectivity reaches 2.84. When the mass ratio of silane coupling agent A-1170 to hydroxyethylidene diphosphate is 3:1 (i.e., Example 3), the selectivity is the best, at 2.64. It has a slow polishing rate for the copper layer but a fast polishing rate for the oxide layer, which can achieve low copper layer loss and high oxide layer removal. In addition, the number of ≥1μm large particles in the polishing solution is maintained within 20,000 particles / mL, which is beneficial to the planarization of the wafer surface.

[0098] In summary, the chemical mechanical polishing slurry of the present invention can achieve selective specificity for copper and oxide layers under low concentration and acidic conditions. It can selectively remove oxide layers while polishing copper layers, resulting in a wafer surface free of defects such as scratches, particles, and dents after polishing, and exhibiting excellent surface quality.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A chemical mechanical polishing slurry, characterized in that, Components including the following mass fractions: 5-7 wt% silica sol, 0.1-1 wt% surfactant, 0.1-1 wt% complexing agent, 0.01-1 wt% corrosion inhibitor, 0.02-2 wt% additives, with the balance being pH adjuster and water; The surfactant is silane coupling agent A-1170.

2. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The complexing agent is selected from one or more of the following: hydroxyethylidene diphosphate, sodium ethylenediaminetetramethyleneide phosphonate, diethylenetriaminepentamethyleneide phosphonate, diethylenetriaminepentacarboxylate, hydrolyzed polymaleic anhydride, polyacrylic acid, polyhydroxyacrylic acid, maleic acid-acrylic acid copolymer, polyacrylamide, ethylenediaminetetraacetic acid, polyaspartic acid, glutamic acid diacetate, methylglycine diacetate, and aspartic acid diacetate; And / or, the corrosion inhibitor is selected from one or more of 5-aminotetrazole, benzotriazole, methylbenzotriazole, imidazole, benzimidazole and 2-mercaptobenzimidazole; And / or, the additives include 0.01-1 wt% oxidant and / or 0.01-1 wt% bactericide.

3. The chemical mechanical polishing slurry as described in claim 2, characterized in that, The oxidant is selected from one or more of hydrogen peroxide, peracetic acid, and ammonium persulfate; And / or, the bactericide is selected from one or more of Kathon, benzisothiazolinone, and methylisothiazolinone.

4. The chemical mechanical polishing slurry as described in claim 2, characterized in that, The mass ratio of the surfactant to the complexing agent is (1-6):

1.

5. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The particle size of the silica sol is 65-75 nm.

6. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The pH value of the chemical mechanical polishing solution is 2-5.

7. The method for preparing the chemical mechanical polishing slurry according to any one of claims 1-6, characterized in that, include: The components are mixed and filtered to obtain the chemical mechanical polishing fluid.

8. The preparation method according to claim 7, characterized in that, Includes the following steps: 1) Water and corrosion inhibitor are mixed to obtain the first mixed solution; 2) Add a complexing agent and a surfactant to the first mixed solution and mix to obtain a second mixed solution; 3) Add silica sol to the second mixed solution and mix to obtain a third mixed solution; 4) Add a pH adjuster to the third mixed solution and mix to obtain a fourth mixed solution; 5) Add additives to the fourth mixed solution, filter, and obtain the chemical mechanical polishing slurry.

9. The use of the chemical mechanical polishing slurry as described in any one of claims 1-6 in planarizing copper layers.

10. Use of silane coupling agent A-1170 in improving the polishing selectivity of chemical mechanical polishing slurries for copper and oxide layers.

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