A complexing surfactant-based acidic copper barrier layer cmp polishing solution and a method for preparing the same

Abstract

The application provides an acidic copper barrier layer CMP polishing solution based on a compounded surfactant and a preparation method thereof, the polishing solution comprises the following components in mass fraction: 1wt%-10wt% of abrasive, 0.1wt%-1wt% of surfactant, 0.04wt%-4wt% of additive, the rest being pH regulator and water, the pH regulator makes the pH value of the polishing solution 2-5; the surfactant is compounded by anionic surfactant and silane coupling agent in a mass ratio of (1-5):1. The polishing solution in the application can realize good polishing selectivity of copper layer, silicon dioxide layer and tantalum nitride barrier layer, the polishing rate of the polishing solution to the copper layer, the silicon dioxide layer and the tantalum nitride barrier layer can be adjusted by adjusting the ratio of the silane coupling agent and the anionic surfactant in the compounded surfactant, the polishing solution is widely applicable to polishing of various copper barrier layers, and has good industrial utilization value.

Description

Technical Field

[0001] This invention belongs to the field of polishing slurry technology, and in particular relates to an acidic copper barrier layer CMP polishing slurry based on a compound surfactant and its preparation method. Background Technology

[0002] Chemical mechanical polishing (CMP) is a key technology for achieving global planarization of wafer surfaces in semiconductor manufacturing. Copper barrier layer polishing slurries are crucial for planarizing copper interconnect structures in CMP, and their performance directly affects polishing results and device quality. Traditional acidic barrier layer polishing slurries often suffer from abrasive particle agglomeration, leading to large particle residues and defects such as wafer surface scratches, severely impacting semiconductor device performance and yield. Surfactants are substances with fixed hydrophilic and lipophilic groups that can orient themselves on the surface of a solution and significantly reduce surface tension. They are a large class of organic compounds with highly distinctive properties, flexible and wide-ranging applications, and significant practical and theoretical value. Surfactants in polishing slurries can disperse abrasive particles, reduce surface tension, and improve wettability, thereby reducing particle agglomeration and surface scratches.

[0003] The polishing process of copper interconnect CMP consists of three steps. The first step is a rapid removal stage of rough copper, which generally uses an alkaline polishing slurry to oxidize and remove the copper. At this stage, the copper removal rate is much higher than that of the dielectric layer and the barrier layer. The second step is a fine polishing process to remove residual copper, ending at the barrier layer. The third step is barrier layer removal, which removes a small amount of copper at a low rate and removes the dielectric layer at a stable high rate. In the third step, the polishing rate of the dielectric layer must be higher than that of the copper. The copper depressions left in the first two steps are corrected by using the difference in polishing rates (selectivity ratio), thus achieving planarization. For different polishing materials, the selectivity ratio of copper / dielectric layer / barrier layer needs to be adjusted and controlled. CN114591686A discloses a polishing slurry for the "third step barrier layer polishing" of copper interconnect. It effectively repairs "dish depressions" and "dielectric erosion" defects by dynamically adjusting the copper removal rate through a "two-component corrosion inhibitor," thereby achieving better global planarization.

[0004] Currently, research has focused on improving polishing slurry performance using single or compound surfactants. While single surfactants can improve certain properties of polishing slurries, it is difficult to simultaneously optimize dispersibility, stability, and polishing effect. Compound surfactants suffer from stability issues; during long-term storage or use, the surfactants may become ineffective, leading to a decrease in the dispersibility of the polishing slurry. CN101372089A discloses an alkaline barrier layer polishing slurry comprising silica sol abrasive, corrosion inhibitor, oxidant, nonionic fluorinated surfactant, and aromatic sulfonic acid oxidant compound. However, the polishing slurry in this patent cannot precisely control the polishing rate of the barrier layer. CN116515397A provides a chemical mechanical polishing slurry for barrier layer planarization and its application method. This chemical mechanical polishing slurry includes abrasive particles, azole compounds, complexing agents, oxidants, water-soluble cellulose, nonionic surfactants, and water. Due to the simultaneous addition of water-soluble cellulose and nonionic surfactants, high removal rates of the barrier layer and dielectric material can be achieved after polishing. However, the above patented technology cannot achieve an adjustable polishing rate selectivity ratio for the dielectric layer / copper / barrier layer, and therefore cannot be widely applied to the polishing of copper barrier layers. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an acidic copper barrier layer CMP polishing slurry based on a compound surfactant and its preparation method, which solves the problems of abrasive agglomeration and poor stability in the prior art, resulting in severe wafer surface defects after polishing, and the inability to achieve an adjustable polishing rate selection ratio of dielectric layer / copper / barrier layer.

[0006] To achieve the above and other related objectives, the present invention provides an acidic copper barrier layer CMP polishing slurry based on a compound surfactant and its preparation method.

[0007] The first aspect of the present invention provides a copper barrier layer polishing slurry, the polishing slurry comprising the following components in the following mass fractions: 1 wt% to 10 wt% abrasive, 0.1 wt% to 1 wt% surfactant, 0.04 wt% to 4 wt% additive, and the balance being a pH adjuster and water, wherein the pH adjuster makes the pH value of the polishing slurry 2 to 5; the surfactant is formed by compounding anionic surfactant and silane coupling agent in a mass ratio of (1 to 5): 1.

[0008] The mass fraction is the percentage of each component relative to the total mass of the polishing slurry, based on the total mass of the polishing slurry.

[0009] Preferably, the pH of the polishing solution is 3-5.

[0010] Considering polishing rate, surface quality and production cost, the mass fraction of the abrasive is preferably 1wt% to 5wt%; for example, it can be 1wt%, 2wt%, 3wt%, 4wt% or 5wt%.

[0011] More preferably, the mass fraction of the abrasive is 3wt% to 5wt%.

[0012] Considering the polishing rate, surface quality, and wetting effect, it is further preferred that the mass fraction of the surfactant is 0.5wt%~1wt%; for example, it can be 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1wt%.

[0013] More preferably, the surfactant has a mass fraction of 0.5wt% to 0.7wt%.

[0014] Preferably, the mass ratio of the anionic surfactant to the silane coupling agent in the surfactant is (1~4):1; including but not limited to 1:1, 2:1, 3:1, 4:1.

[0015] Preferably, the additive comprises the following components:

[0016] 1) 0.01wt%~1wt% of bactericide;

[0017] 2) Complexing agent of 0.01wt%~1wt%;

[0018] 3) Oxidizing agent of 0.01wt%~1wt%;

[0019] 4) 0.01wt%~1wt% corrosion inhibitor.

[0020] In order to simultaneously achieve effective sterilization without causing side reactions with other components in the polishing liquid, it is further preferred that the mass fraction of the bactericide is 0.1wt%~1wt%; for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1wt%.

[0021] More preferably, the mass fraction of the bactericide is 0.1wt% to 0.5wt%.

[0022] Considering the removal rate, polishing selectivity, surface quality, and stability of the polishing solution, it is further preferred that the mass fraction of the complexing agent is 0.1wt%~1wt%; for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1wt%.

[0023] More preferably, the complexing agent has a mass fraction of 0.1wt% to 0.5wt%.

[0024] Considering the removal rate, polishing selectivity, surface quality, and stability of the polishing solution, it is further preferred that the mass fraction of the oxidant is 0.1wt%~1wt%; for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1wt%.

[0025] More preferably, the oxidant has a mass fraction of 0.1 wt% to 0.5 wt%.

[0026] Considering the removal rate, polishing selectivity, surface quality, and stability of the polishing solution, it is further preferred that the mass fraction of the corrosion inhibitor is 0.1wt%~1wt%; for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1wt%.

[0027] More preferably, the corrosion inhibitor has a mass fraction of 0.1wt% to 0.5wt%.

[0028] Preferably, the bactericide is selected from any one or more of Kathon, benzisothiazolinone, and methylisothiazolinone.

[0029] The bactericides in the polishing solution can inhibit and kill microorganisms, maintaining the chemical stability, colloidal stability, and performance consistency of the polishing solution during storage and use.

[0030] Preferably, the complexing agent is any one or more selected from hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, and ethylenediaminetetramethylenephosphonic acid.

[0031] Complexing agents in polishing slurries can help dissolve and remove polishing products, control corrosion and surface roughness, and stabilize the polishing slurry system.

[0032] Preferably, the oxidant is any one or more selected from hydrogen peroxide, peracetic acid, and ammonium persulfate.

[0033] The oxidant in the polishing slurry can undergo an oxidation-reduction reaction with the surface of metal or semiconductor materials, forming a softening film on the material surface. This makes it easier for the abrasive to scrape off the soft film through mechanical action, and it is less likely to damage the material surface.

[0034] Preferably, the corrosion inhibitor is any one or more selected from 5-aminotetrazole, benzotriazole, methylbenzotriazole, imidazole, benzimidazole, and 2-mercaptobenzimidazole.

[0035] The corrosion inhibitor in the polishing slurry can selectively protect and inhibit the static corrosion of the oxidant in the polishing slurry, ensuring local planarization.

[0036] Preferably, the anionic surfactant is a disulfonic acid diphenyl ether anionic surfactant.

[0037] Preferably, the silane coupling agent is selected from any one or more of epoxy silane coupling agents, bisamino silane coupling agents, and monoamino silane coupling agents.

[0038] More preferably, the anionic surfactant is any one or more selected from disodium decyl(sulfonylphenoxy)benzenesulfonate, disodium nonyl(sulfonylphenoxy)benzenesulfonate, and sodium dodecyl diphenyl ether disulfonate;

[0039] More preferably, the silane coupling agent is any one or more selected from silane coupling agent A-187, silane coupling agent A-1170, and silane coupling agent KH550.

[0040] Preferably, the abrasive is silica sol.

[0041] More preferably, the silica sol is an aqueous solution containing 30wt%~35wt% silica.

[0042] More preferably, the average particle size of the abrasive is 50~100nm; for example, it can be 50nm, 60nm, 70nm, 80nm, 90nm, or 100nm.

[0043] More preferably, the average particle size of the abrasive is 60~80nm.

[0044] Preferably, the pH adjuster is selected from any one or more of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and acetic acid.

[0045] Preferably, under the following conditions: polishing pressure: 5 pis for the holding ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; polishing speed: HS / PS = 93 / 87 rpm; polishing fluid flow rate: 300 ml / min; and temperature: 25°C, the polishing rate of the above polishing fluid on copper is 250~450 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, and 450 Å / min.

[0046] Preferably, under the following conditions: polishing pressure: 5 pis for the holding ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; polishing speed: HS / PS = 93 / 87 rpm; polishing fluid flow rate: 300 ml / min; and temperature: 25°C, the polishing rate of the above polishing fluid on silicon dioxide is 700~1100 Å / min; including but not limited to 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, and 1100 Å / min.

[0047] Preferably, under the following conditions: polishing pressure: 5 pis for the holding ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; polishing speed: HS / PS = 93 / 87 rpm; polishing fluid flow rate: 300 ml / min; and temperature: 25°C, the polishing rate of the above polishing fluid on tantalum nitride is 400-500 Å / min; including but not limited to 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, and 500 Å / min.

[0048] Preferably, under the following conditions: polishing pressure: 5 pis for the holding ring, 3 pis for Zone 1, and 2 pi for Zones 2-7; polishing speed: HS / PS = 93 / 87 rpm; polishing fluid flow rate: 300 ml / min; and temperature: 25°C, the polishing selectivity ratio of the above polishing fluid for silicon dioxide / copper is 2-3; including but not limited to 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and 3.

[0049] Where HS is the rotation speed of the polishing head per minute, and PS is the revolution speed of the polishing head around the central axis of the machine per minute.

[0050] Preferably, the number of large particles ≥0.5μm in each 1mL of polishing liquid is 150,000 to 220,000; for example, it can be 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, or 220,000.

[0051] Preferably, the number of large particles ≥1μm in each 1mL of polishing liquid is 30,000 to 50,000; for example, it can be 30,000, 40,000, or 50,000 particles.

[0052] A second aspect of the present invention provides a method for preparing the above-mentioned polishing liquid, the method comprising: mixing and dispersing the components, filtering and filling to obtain the polishing liquid.

[0053] The preparation method has restrictions on the mixing order of the components. The selectivity adjuster and additives are mixed with water, abrasive is added, and then a pH adjuster is added to adjust the polishing solution to the required pH value. To make the prepared polishing solution more stable and the pH value more accurate, preferably, the preparation method is carried out according to the following steps:

[0054] S1. Add water, surfactant, and some additives, stir, and obtain the first mixed solution;

[0055] S2. Add abrasive to the first mixed solution and stir to obtain the second mixed solution;

[0056] S3. Add pH adjuster to the second mixed solution and stir to obtain the third mixed solution;

[0057] S4. Add the remaining additives to the third mixed solution, stir, filter and fill to obtain the polishing liquid.

[0058] The additives added in S1 above are all additives except for the bactericide. The additives in S4 above are bactericides. Adding the bactericide last can effectively inhibit bacteria in the entire polishing solution.

[0059] The abrasive is added in S2 to prevent premature addition and flocculation or sedimentation with other additives.

[0060] Adding a pH adjuster to S3 makes the pH of the entire polishing solution more precise.

[0061] Preferably, the stirring speed in each of the preparation methods S1 to S4 is 100 to 500 r / min; for example, it can be 100 r / min, 200 r / min, 300 r / min, 400 r / min, or 500 r / min.

[0062] Preferably, the stirring speed in each of the above preparation methods S1 to S4 is 150 to 250 r / min.

[0063] Preferably, the stirring time in each of the preparation methods S1 to S4 is 10 to 60 min; for example, it can be 10 min, 20 min, 30 min, 40 min, 50 min, or 60 min.

[0064] Preferably, the filtration in the above preparation method includes primary filtration and secondary filtration, wherein the primary filtration is performed using a 1μm filter element and the secondary filtration is performed using a 0.5μm filter element.

[0065] A third aspect of the present invention provides an application of the above-mentioned polishing slurry in the polishing of copper barrier layers.

[0066] Preferably, the application includes a copper barrier layer polishing process in which the polishing rate of the polishing slurry on the copper layer is controlled at 200~400 Å / min, the polishing rate on the dielectric layer is controlled at 700~1100 Å / min, and the polishing rate on the barrier layer is controlled at 400~500 Å / min.

[0067] Within the aforementioned polishing rate range, both sufficient polishing rate of the polishing slurry and a flat surface of the wafer after polishing are ensured. For example... Figure 1 As shown in the barrier layer polishing process, if the polishing rate of copper is too low (<200 Å / min), it will lead to a longer polishing time, exacerbate the erosion of other layers, and make it impossible to remove residual copper film within the set time, resulting in incomplete exposure of the barrier layer and short-circuit defects. If the polishing rate of copper is too high (>400 Å / min), it will narrow the polishing process window, increase the difficulty of control, and lead to more severe butterfly-shaped depressions and erosion, resulting in poor uniformity of the wafer surface. If the polishing rate of the dielectric layer is too low (<700 Å / min), the surface of the dielectric layer will still be uneven after polishing of copper and barrier layer, which is not conducive to global planarization. If the polishing rate of the dielectric layer is too high (>1100 Å / min), it will exacerbate the erosion of the dielectric layer, making the trenches deeper and causing local non-uniformity. If the polishing rate of the barrier layer is too low (<400 Å / min), the residual conductive barrier layer will cause a short circuit between adjacent copper lines, resulting in chip failure; if the polishing rate of the barrier layer is too high (>500 Å / min), severe erosion of the barrier layer may cause localized penetration, damaging the underlying structure and leading to chip failure.

[0068] The fourth aspect of the present invention provides the use of an anionic surfactant and a silane coupling agent as a surfactant in a polishing slurry for controlling the polishing selectivity ratio of silica to copper.

[0069] Preferably, the application includes adjusting the polishing selectivity ratio of silicon dioxide to copper to be between 2 and 3.

[0070] As described above, the acidic copper barrier layer CMP polishing slurry based on a compound surfactant and its preparation method of the present invention have the following beneficial effects:

[0071] This invention provides a novel acidic polishing slurry suitable for copper barrier layers. By employing a compound surfactant (a combination of silane coupling agent and anionic surfactant), the problem of large particle agglomeration in the polishing slurry can be significantly reduced, ensuring that the slurry maintains good dispersibility and stability during long-term storage and use. Furthermore, the polishing slurry of this invention achieves good polishing selectivity for copper layers, silica layers, and tantalum nitride barrier layers. The polishing rate of the slurry for copper layers, silica layers, and tantalum nitride barrier layers can be adjusted by changing the ratio of silane coupling agent and anionic surfactant in the compound surfactant. It is widely applicable to polishing various copper barrier layers and has good industrial application value. Attached Figure Description

[0072] Figure 1 The diagram shown is a schematic of the copper barrier layer polishing process in this invention. Detailed Implementation

[0073] The following specific examples 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. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0074] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0075] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the presence of other method steps before or after the combined steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0076] 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; in the specification and claims of the present invention, unless otherwise expressly stated in the text, the singular forms "a", "an" and "this" include the plural forms.

[0077] 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.

[0078] Based on existing technology and the applicant's experimental research, it has been found that in the copper barrier layer polishing process, the polishing rate of the polishing slurry on the copper layer should be controlled at 200~400 Å / min, the polishing rate on the dielectric layer at 700~1100 Å / min, and the polishing rate on the barrier layer at 400~500 Å / min. Within this range, the polishing slurry has sufficient polishing speed while also ensuring a flat surface on the wafer after polishing. However, in the polishing process of copper barrier layers with different polishing materials, the optimal polishing rate applicable to the dielectric layer / copper / barrier layer varies in order to maximize surface flatness. Therefore, there is an urgent need for a polishing slurry that can adjust the polishing rate selection ratio of the dielectric layer / copper / barrier layer. Therefore, in this application, the applicant uses a surfactant formed by combining anionic surfactant and silane coupling agent to form a polishing solution together with other components. This polishing solution has a suitable polishing rate for copper, dielectric layer and barrier layer. Furthermore, by changing the ratio of anionic surfactant and silane coupling agent, the polishing rate of dielectric layer / copper / barrier layer and the polishing selectivity ratio of dielectric layer / copper can be dynamically controlled, making it suitable for different polishing materials.

[0079] The abrasive used in the following embodiments of this application is silica sol, wherein the content of silicon oxide is 30.5 wt%. The mass fraction of the abrasive described below refers to the mass fraction of solid silicon oxide abrasive in the entire polishing slurry.

[0080] Example 1

[0081] This embodiment 1 provides a specific acidic copper barrier polishing slurry. Based on the total mass of the polishing slurry, its specific composition is as follows: 4 wt% silica abrasive with an average particle size of 70 nm, 0.6 wt% composite surfactant, 0.2 wt% bactericide, 0.1 wt% complexing agent, 0.4 wt% oxidant, 0.3 wt% corrosion inhibitor, and the balance being pH adjuster and water. The composite surfactant is formed by compounding disodium decyl(sulfonylphenoxy)benzenesulfonate and silane coupling agent A-1170 in a 1:1 ratio. The bactericide is Kathon, the complexing agent is hydroxyethylidene diphosphonic acid, the oxidant is hydrogen peroxide, the corrosion inhibitor is 5-aminotetrazolium, the pH adjuster is nitric acid, and the pH of the polishing slurry is 4.

[0082] The specific preparation method of this polishing slurry is as follows:

[0083] S1. Add water to a clean reactor according to the ratio and start stirring at 200 r / min.

[0084] S2. Add corrosion inhibitor, complexing agent and compound surfactant according to the ratio, and continue stirring until they are completely dissolved.

[0085] S3. After the above process has dissolved, add the abrasive, keep the speed constant, and stir for 1 hour.

[0086] S4. Adjust the pH of the polishing solution to 4; keep the speed constant and stir for 30 minutes.

[0087] S5. Add bactericide, keep the speed constant, and stir for 1 hour.

[0088] S6. After passing through a primary filter element (1µm filter element) and a secondary filter element (0.5µm filter element) of the Kobote filter, the solution is filled to obtain the acidic copper barrier layer polishing liquid.

[0089] Example 2

[0090] This embodiment 2 provides a specific acidic copper barrier layer polishing slurry and its preparation method. The difference between this embodiment and embodiment 1 is that the silane coupling agent A-1170 is replaced with the silane coupling agent KH550; the remaining components and preparation methods are the same as in embodiment 1.

[0091] Example 3

[0092] This embodiment 3 provides a specific acidic copper barrier layer polishing liquid and its preparation method. The difference between this embodiment and embodiment 1 is that the composite surfactant is formed by compounding disodium decyl(sulfonylphenoxy)benzenesulfonate and silane coupling agent A-1170 in a 2:1 ratio; the remaining components and preparation methods are the same as in embodiment 1.

[0093] Example 4

[0094] This embodiment 4 provides a specific acidic copper barrier polishing slurry and its preparation method. The difference between this slurry and that of embodiment 1 is that the composite surfactant is formed by compounding disodium decyl(sulfonylphenoxy)benzenesulfonate and silane coupling agent A-1170 in a 3:1 ratio; the remaining components and preparation methods are the same as those in embodiment 1.

[0095] Example 5

[0096] This Example 5 provides a specific acidic copper barrier polishing slurry and its preparation method. The difference between this slurry and Example 1 is that the composite surfactant is formed by compounding disodium decyl(sulfonylphenoxy)benzenesulfonate and silane coupling agent A-1170 in a ratio of 4:1; the remaining components and preparation methods are the same as in Example 1.

[0097] Example 6

[0098] This embodiment 6 provides a specific acidic copper barrier layer polishing slurry and its preparation method. The difference between this embodiment and embodiment 4 is that the pH of the polishing slurry is 3; the remaining components and preparation methods are the same as in embodiment 4.

[0099] Example 7

[0100] This embodiment 7 provides a specific acidic copper barrier layer polishing slurry and its preparation method. The difference between this embodiment and embodiment 4 is that the pH of the polishing slurry is 5; the remaining components and preparation methods are the same as in embodiment 4.

[0101] Comparative Example 1

[0102] Comparative Example 1 provides a specific acidic copper barrier layer polishing slurry and its preparation method. The difference between this slurry and Example 1 is that a single silane coupling agent, KH550, is used as the surfactant; the remaining components and preparation methods are the same as in Example 1.

[0103] Comparative Example 2

[0104] Comparative Example 2 provides a specific acidic copper barrier layer polishing slurry and its preparation method. The difference between it and Example 1 is that a single silane coupling agent A-1170 is used as the surfactant; the remaining components and preparation methods are the same as in Example 1.

[0105] Comparative Example 3

[0106] Comparative Example 3 provides a specific acidic copper barrier polishing solution and its preparation method. The difference between this solution and Example 1 is that a single disodium decyl(sulfonylphenoxy)benzenesulfonate is used as the surfactant; the remaining components and preparation methods are the same as in Example 1.

[0107] Test section

[0108] The polishing performance of the acidic copper barrier layer polishing slurries prepared in Examples 1-7 and Comparative Examples 1-3 of this application was tested. The process conditions for polishing the wafers are as follows:

[0109] Polishing target: 12-inch wafer (Cu / Oxide / T AN)

[0110] Polishing pad: KC-100

[0111] Polishing pressure: 5 pis for retaining ring, 3 pis for Zone 1, and 2 pis for Zones 2-7.

[0112] Polishing speed: HS / PS = 93 / 87 rpm

[0113] Polishing fluid flow rate: 300 ml / min

[0114] Polishing temperature: 25℃

[0115] Polishing time: 60s

[0116] The polishing rate was measured using a KLA non-metallic film thickness gauge (F50) and a metallic film thickness gauge (R54) on the copper conductive layer, silicon oxide dielectric layer, and tantalum nitride barrier layer. Specifically, the thicknesses of these layers were measured before and after polishing. The polishing rate was calculated by dividing the difference in film thickness before and after polishing by the polishing time. The formulations of each polishing solution are shown in Table 1, and the polishing rate test results are shown in Table 2. The selection ratio is the ratio of the silicon oxide polishing rate to the copper polishing rate.

[0117] Furthermore, the polishing solution was collected 7 days after filling and the number of large particles 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.

[0118] Furthermore, to evaluate the storage stability of the polishing slurry, the particle size, zeta potential, and viscosity of the polishing slurry prepared in Example 4 were monitored over three months. Particle size and zeta potential were measured using a nanoparticle size potentiometer, and viscosity was measured using a Brookfield DV2T viscometer at 25°C. Specific test results are shown in Table 3.

[0119] Table 1 Composition and Formulation of Polishing Fluid

[0120]

[0121]

[0122] Table 2. Polishing rate and silica / copper selectivity ratio test results of polishing slurry.

[0123]

[0124] Table 3. Stability test results of the polishing slurry in Example 4

[0125] Day 1 70.3 -36.64 2.05 4.02 Day 7 70.5 -35.13 2.02 4.01 Day 14 70.5 -37.96 2.03 4.02 Day 21 70.2 -36.75 2.01 4.04 Day 28 70 -36.28 2.04 4.01 Day 58 70.4 -34.81 2.03 4.02 Day 88 70.5 -36.94 2.03 4.03

[0126] The polishing rate results in Table 2 show that: in Comparative Examples 1 and 2, when only a single silane coupling agent was added as a surfactant, the polishing rate of the polishing solution for copper, silicon dioxide, and tantalum nitride was relatively fast, which was not conducive to wafer surface planarization and easily led to defects; in Comparative Example 3, when only disodium decyl(sulfonylphenoxy)benzenesulfonate was added as a surfactant, the polishing rate of the polishing solution for copper and silicon dioxide was relatively slow, and the polishing rate for the barrier layer was moderate. This resulted in the barrier layer being preferentially etched away, while copper and dielectric layers remained, leading to depressions and hindering wafer surface planarization; the polishing solutions prepared in Examples 1-7 had a polishing rate of 250-400 for copper. The polishing rate is 700-1100 Å / min for silica and 400-500 Å / min for TaN. The polishing selectivity ratio of silica to copper is 2-3, which is suitable for polishing copper barrier layers. In addition, the results of Examples 1 and 3-5 show that the polishing rate and polishing selectivity ratio of the polishing slurry for silica and copper can be adjusted by changing the ratio of disodium decyl(sulfonylphenoxy)benzenesulfonate and silane coupling agent A-1170. As the proportion of disodium decyl(sulfonylphenoxy)benzenesulfonate increases, the polishing rate of the polishing slurry for silica and copper gradually decreases, while the polishing selectivity ratio of silica to copper gradually increases.

[0127] Table 2 shows the results of large particle detection in the polishing slurry. It can be seen that the polishing slurries in Comparative Examples 1-3, which used a single surfactant, contained a large number of large particles (more than 300,000 particles larger than or equal to 0.5 μm and more than 70,000 particles larger than or equal to 1 μm per mL of polishing slurry). This leads to the easy aggregation of large particles in the polishing slurry, affecting not only the surface quality of the polished wafer but also the stability of the polishing slurry, making it difficult to store. The polishing slurries in Examples 1-7, which used a compound surfactant, contained a moderate number of large particles (between 150,000 and 220,000 particles larger than or equal to 0.5 μm and between 30,000 and 50,000 particles larger than or equal to 1 μm per mL of polishing slurry). This ensured sufficient particles for polishing while minimizing the impact of large particle aggregation on the surface quality of the wafer while maintaining the polishing rate.

[0128] As can be seen from the results in Table 3, the polishing slurry prepared in Example 4 showed very little change in particle size, potential, viscosity and pH over three months, demonstrating excellent stability.

[0129] In summary, this invention utilizes a surfactant formed by compounding anionic surfactants and silane coupling agents, along with abrasives, bactericides, complexing agents, oxidants, corrosion inhibitors, pH adjusters, and water to form a polishing slurry. This polishing slurry is suitable for polishing the barrier layer in copper interconnect CMP processes, exhibiting a moderate polishing rate for copper, dielectric layers, and barrier layers. It achieves surface planarization while ensuring the polishing rate. Furthermore, by changing the compounding ratio of anionic surfactants and silane coupling agents, the polishing rate of the dielectric layer / copper / barrier layer and the polishing selectivity ratio of the dielectric layer / copper can be dynamically controlled to suit different polishing materials, demonstrating broad application prospects.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A copper barrier layer polishing slurry, characterized in that, The polishing slurry comprises the following components in the following mass fractions: 1 wt% to 10 wt% abrasive, 0.1 wt% to 1 wt% surfactant, 0.04 wt% to 4 wt% additives, and the balance being a pH adjuster and water. The pH adjuster adjusts the pH of the polishing slurry to 3 to 5. The surfactant is formed by compounding anionic surfactant and silane coupling agent in a mass ratio of (1 to 5):

1. The additives comprise the following components: 1) 0.01wt%~1wt% of bactericide; 2) Complexing agent of 0.01wt%~1wt%; 3) Oxidizing agent of 0.01wt%~1wt%; 4) 0.01wt%~1wt% corrosion inhibitor; The anionic surfactant is a disulfonic acid diphenyl ether anionic surfactant; The silane coupling agent is selected from any one or more of epoxy silane coupling agents, bisamino silane coupling agents, and monoamino silane coupling agents.

2. The polishing slurry according to claim 1, characterized in that, The abrasive is silica sol; And / or, the pH adjuster is any one or more selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and acetic acid.

3. The polishing slurry according to claim 1, characterized in that, The bactericide is selected from any one or more of Kathon, benzisothiazolinone, and methylisothiazolinone; And / or, the complexing agent is any one or more selected from hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, and ethylenediaminetetramethylenephosphonic acid; And / or, the oxidant is any one or more selected from hydrogen peroxide, peracetic acid, and ammonium persulfate; And / or, the corrosion inhibitor is any one or more selected from 5-aminotetrazole, benzotriazole, methylbenzotriazole, imidazole, benzimidazole, and 2-mercaptobenzimidazole.

4. The polishing slurry according to claim 1, characterized in that, The anionic surfactant is selected from any one or more of decyl(sulfonylphenoxy)benzenesulfonate disodium, nonyl(sulfonylphenoxy)benzenesulfonate disodium, and dodecyl diphenyl ether disulfonate sodium; And / or, the silane coupling agent is any one or more selected from silane coupling agent A-187, silane coupling agent A-1170, and silane coupling agent KH550.

5. A method for preparing a polishing slurry as described in any one of claims 1 to 4, characterized in that, The preparation method includes: mixing and dispersing the components, filtering and filling to obtain the polishing liquid.

6. The preparation method according to claim 5, characterized in that, The preparation method includes: S1. Add water, surfactant, and some additives, stir, and obtain the first mixed solution; S2. Add abrasive to the first mixed solution and stir to obtain the second mixed solution; S3. Add pH adjuster to the second mixed solution and stir to obtain the third mixed solution; S4. Add the remaining additives to the third mixed solution, stir, filter and fill to obtain the polishing liquid.

7. The application of the polishing slurry as described in any one of claims 1 to 4 in the polishing of copper barrier layers.

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