Cleaning fluid used after chemical mechanical polishing of semiconductor chip, and preparation method and application thereof

Abstract

The invention provides a cleaning solution for a semiconductor chip after chemical mechanical polishing, and a preparation method and application thereof, the cleaning solution for the semiconductor chip after chemical mechanical polishing comprises the following components by mass: 5-20 parts of a strong base; 5-30 parts of a weak base; 0.5-3 parts of a cellulose derivative; 0.5 to 2 parts of a chitin derivative; and 70-95 parts of ultrapure water. The cellulose derivative is one or more of 2, 5-furandicarboxylic acid, levulinic acid and 5-aminolevulinic acid. The chitin derivative is one or more of chitosan oligosaccharide, carboxymethyl chitosan, N-acetyl glucose, glucosamine and carboxymethyl glucosamine. According to the cleaning solution for the semiconductor chip after chemical mechanical polishing, CuO generated on the surface of copper after CMP can be effectively removed, a monomolecular adsorption layer is generated on the surface of Cu, and reoxidation of the surface of Cu is effectively inhibited within waiting time, so that Vbd is prevented from being reduced, and the reliability of a gate oxide layer of an MOS (Metal Oxide Semiconductor) device is improved.

Description

Cleaning liquid for semiconductor chips after chemical mechanical polishing, preparation method and use thereof Technical Field

[0001] The present invention relates to cleaning technology, in particular to a cleaning liquid for semiconductor chips after chemical mechanical polishing, a preparation method and application thereof. Background Art

[0002] Currently, as the feature size of semiconductor devices becomes smaller and smaller, copper has been widely used in the internal interconnects of semiconductor components in order to reduce interconnect delay. In the traditional multi-layer copper interconnect process, after the copper electroplating is completed, chemical mechanical polishing (CMP) is required to remove excess copper. There are many pollutants on the surface of the wafer after the CMP process, such as particulate pollutants. These particles come from the grinding fluid, grinding pad, and ground copper residues. Among them, Cu and CuO particle contamination will have a greater impact on the chip and may cause a short circuit. In addition, the Cu surface after the CMP process is oxidized to CuO, and CuO is hydrophobic, which is not conducive to subsequent cleaning. The main reason is that the surface of pure copper is hydrophilic and can be completely soaked in water, forming a water film. During the next cleaning step, the high-speed rotating wafer surface is wetted by pure water. When the cleaning roller brush approaches, the brush slides on the water film on the wafer surface without directly contacting the wafer surface. Instead, the thin film of pure water moves at high speed across the lens surface, and the resulting friction removes contaminant particles from the wafer surface. However, once the copper surface is oxidized to CuO, it becomes hydrophobic and does not adhere to water, preventing the formation of a water film. At this time, cleaning with a brush causes the brush to directly contact the wafer surface, causing particles originally attached to the brush to adhere to the wafer surface again, causing secondary contamination.

[0003] Therefore, in order to make the cleaning procedure after CMP can more thoroughly remove pollutant particles, the prior art is generally, after carrying out CMP, the wafer is placed in an acidic or alkaline cleaning solution to clean the above-mentioned multiple pollutants, thereby reaching the purpose of cleaning the wafer surface. However, there are many shortcomings in the prior art. The Cu surface known to be polished by chemical mechanical polishing is usually covered with an oxide film, with the top layer being CuO, the middle layer being Cu2O, and the substrate being Cu. Acidic copper post-CMP cleaning solution can dissolve CuO and Cu2O on the copper surface, while alkaline semiconductor chip chemical mechanical polishing post-cleaning solution can selectively dissolve CuO, leaving Cu2O to passivate the surface, and acidic cleaning solution can cause more serious Cu damage, so it is less used at present.

[0004] After cleaning, the next step is film deposition, but this process typically doesn't begin immediately; there's a waiting period (Q-time). During this waiting period, the wafer is exposed to an O2-containing environment, so there's a risk of re-oxidation of the Cu2O on the wafer surface. Generally, the waiting time cannot exceed four hours. This is because after four hours, the wafer surface will oxidize, forming a CuO film that exceeds the thickness limit. Due to its poor conductivity, CuO can increase circuit impedance or cause short circuits between metal layers. In severe cases, it can render the wafer scrapped, significantly impacting yield.

[0005] Experiments have shown that the waiting time between the copper CMP step and the subsequent barrier layer deposition step in the above-mentioned traditional method is a very important technical indicator. It is closely related to the TDDB (Time Dependent Dielectric Breakdown) of semiconductor devices. TDDB is a common method to measure the reliability of the gate oxide layer of MOS (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET, abbreviated as MOS) devices. Specifically, it refers to the time required for a strong electric field to break through a gate oxide layer, which is also related to the breakdown voltage (V) of the electric field. bd ) are closely connected. In actual production, V bd It can be regarded as a parameter for rapid detection of TDDB. The longer the waiting time, the thicker the CuO film, the longer the TDDB, and the longer the V bd The smaller the gate oxide layer, the worse the reliability of the MOS device. Therefore, in order to improve the reliability of the device, the speed of re-oxidation of the surface after cleaning must be suppressed and the process window must be widened.

[0006] The second disadvantage of the existing technology: As mentioned above, the CuO film formed on the wafer surface during the CMP process and the subsequent waiting time will make the wafer surface hydrophobic, preventing the formation of a water film. At this time, using a roller brush for cleaning will cause the brush to directly contact the wafer surface, causing particles originally attached to the brush to be transferred to the wafer surface, causing secondary contamination and increasing the difficulty of subsequent cleaning. Therefore, to avoid secondary contamination of the wafer, removing the CuO film is necessary.

[0007] In summary, if CuO can be removed as soon as possible after the copper CMP step and the oxidation rate of the clean surface can be slowed down during the waiting time, the waiting time between the copper CMP and the subsequent barrier layer deposition step can be extended, which will greatly facilitate production and also help prevent V bd The reduction creates favorable conditions, thereby improving the reliability of the gate oxide layer of the MOS device.

[0008] CN103232885A discloses an emulsified oil for cooling copper rods during the production of electromagnetic wires. The octylphenol polyoxyethylene ether described therein acts as a reducing agent to remove copper oxide, while the sodium petroleum sulfonate acts as a metal corrosion inhibitor to prevent copper rust.

[0009] CN1680626A discloses a cleaning solution for semiconductor chips after chemical mechanical polishing, which removes impurities from the surface of the Si chip through the combined action of multiple additives, such as organic acid chelating agents, preservatives, corrosion inhibitors, surfactants, etc.

[0010] CN113151838A discloses a post-chemical mechanical polishing cleaning solution. By adding an antioxidant, a copper complex, a corrosion inhibitor, a chelating agent, and a surfactant, it achieves high cleaning performance, low material corrosion, and good BTA removal. The corrosion inhibitor, 2-mercaptobenzothiazole, the heteropolycyclic copper complex, and the surfactant, dodecylbenzenesulfonic acid, are all petroleum-derived products.

[0011] In the aforementioned patent, the post-polishing cleaning fluid must remove particulate matter, remove metal contamination, and inhibit metal corrosion. Therefore, numerous compounds are added, many of which are derived from petroleum. Petroleum is a non-renewable resource, and its use has led to increasing industry attention regarding environmental pollution, climate change, and resource and energy crises. The development of green energy is a top priority today.

[0012] Summary of the Invention

[0013] The purpose of the present invention is to solve the problem that the traditional acid and alkaline cleaning solutions have unsatisfactory CuO cleaning effects and the re-formation of CuO film during the waiting period. A cleaning solution for semiconductor chips after chemical mechanical polishing is proposed. The cleaning solution can effectively remove CuO formed on the surface after copper CMP and form a monomolecular adsorption layer on the Cu surface, effectively inhibiting the re-oxidation of the Cu surface during the waiting period, thereby preventing V bd The reduction of the gate oxide layer of the MOS device improves the reliability of the gate oxide layer of the MOS device.

[0014] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "consisting of..." etc. and similar meanings.

[0015] To achieve the above object, the technical solution adopted by the present invention is: a cleaning solution for semiconductor chips after chemical mechanical polishing, comprising the following components in the following mass proportions:

[0016] Furthermore, the strong base is an organic strong base and / or an inorganic strong base.

[0017] Furthermore, the inorganic strong base is potassium hydroxide and / or cesium hydroxide.

[0018] Furthermore, the organic strong base is a quaternary ammonium hydroxide.

[0019] Furthermore, the quaternary ammonium hydroxide is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, dimethyldiethylammonium hydroxide, (2-hydroxyethyl)trimethylammonium hydroxide and tris(2-hydroxyethyl)-methylammonium hydroxide.

[0020] Furthermore, the quaternary ammonium hydroxide is preferably one or more of tetramethylammonium hydroxide, tetrabutylammonium hydroxide and tris(2-hydroxyethyl)-methylammonium hydroxide.

[0021] Furthermore, the mass fraction of the strong base is 5-20 parts, for example, 5 parts, 10 parts, 15 parts or 20 parts.

[0022] Furthermore, the amount of the strong base is preferably 5-10 parts.

[0023] Furthermore, the weak base is an organic alcohol amine.

[0024] Furthermore, the organic alcohol amine is one or more of monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N,N-dimethylethanolamine, N-ethylethanolamine, N-phenylethanolamine, N-methyldiethanolamine, isopropanolamine, triisopropanolamine and diglycolamine.

[0025] Furthermore, the organic alcohol amine is preferably one or more of triethanolamine, diglycolamine and N-methylethanolamine.

[0026] Furthermore, the mass fraction of the weak base is 5-30 parts, for example, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts or 30 parts.

[0027] Furthermore, the weak base is preferably 5-20 parts.

[0028] The cleaning solution of the present invention provides an alkaline environment, which can enhance the electrostatic repulsion between particle contaminants and the substrate, completely remove abrasive particle contamination and metal particle contamination, and prevent particle re-adsorption. The present invention improves the pH and buffering capacity of the system by mixing strong and weak bases.

[0029] Furthermore, the cellulose derivative is obtained by degradation and conversion of cellulose, and the cellulose derivative is one or more of 2,5-furandicarboxylic acid, levulinic acid and 5-aminolevulinic acid.

[0030] Furthermore, the cellulose derivative is preferably two of 2,5-furandicarboxylic acid, levulinic acid and 5-aminolevulinic acid.

[0031] Furthermore, the cellulose derivative is more preferably 2,5-furandicarboxylic acid and 5-aminolevulinic acid.

[0032] The cellulose derivative of the present invention uses 2,5-furandicarboxylic acid and 5-aminolevulinic acid simultaneously, and the corrosion of the carboxyl group and the chelation of the amino group work together to remove CuO more quickly.

[0033] Furthermore, the weight ratio of the 2,5-furandicarboxylic acid to 5-aminolevulinic acid is 4:1-1:4.

[0034] Furthermore, the weight ratio of the 2,5-furandicarboxylic acid to 5-aminolevulinic acid is preferably 2:1-1:4.

[0035] Furthermore, the weight ratio of the 2,5-furandicarboxylic acid to 5-aminolevulinic acid is more preferably 1:1.

[0036] Furthermore, the mass proportion of the cellulose derivative is 0.5-3 parts, for example, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts or 3 parts.

[0037] Furthermore, the cellulose derivative is preferably 0.5-2.5 parts.

[0038] Biomass resources are the only renewable carbon source on Earth. Cellulose, hemicellulose, lignin, chitin, and other biomass energy sources are all considered. Cellulose has the highest production volume and is the world's largest renewable resource. Cellulose conversion can produce platform compounds such as 5-hydroxymethylfurfural, 2,5-furandicarboxylic acid, levulinic acid, and 5-aminolevulinic acid. These platform compounds have applications in polyesters, polyamides, metal-organic frameworks, pharmaceutical synthesis, and plasticizers. The cellulose derivatives in the cleaning solution of the present invention can effectively remove CuO formed by the oxidation of Cu in the polishing solution.

[0039] Furthermore, the chitin derivative is one or more of chitosan oligosaccharide, carboxymethyl chitosan, N-acetylglucosamine, glucosamine and carboxymethylglucosamine.

[0040] Furthermore, the chitosan derivative includes a component A and a component B, wherein the component A is chitosan oligosaccharide and / or carboxymethyl chitosan; and the component B is one or more of N-acetylglucose, glucosamine, and carboxymethyl glucosamine. The simultaneous use of components A and B can achieve better reoxidation inhibition and corrosion inhibition because the small molecule chitosan derivative can be embedded in the higher molecular weight chitosan oligosaccharide and carboxymethyl chitosan, forming a dense protective film on the Cu surface.

[0041] Furthermore, the mass ratio of component A to component B is 3:1-1:3.

[0042] Furthermore, the mass ratio of component A to component B is preferably 2:1-1:2.

[0043] Furthermore, the mass ratio of component A to component B is more preferably 2:1.

[0044] Furthermore, the polymerization degree of the chitosan oligosaccharide is an integer of 2-20.

[0045] Furthermore, the degree of polymerization of the chitosan oligosaccharide is preferably 4-8.

[0046] Furthermore, the molecular weight of the carboxymethyl chitosan is 1000-10000, for example, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000 or 10000.

[0047] Furthermore, the molecular weight of the carboxymethyl chitosan is preferably 3000-5000.

[0048] Furthermore, the mass fraction of the chitosan derivative is 0.5-2 parts, for example, 0.5 parts, 1 part, 1.5 parts or 2 parts.

[0049] Furthermore, the chitosan derivative is preferably 0.5-1.5 parts.

[0050] Chitin is the largest nitrogen-containing natural organic polymer in nature, after protein. It can be extracted from the shells of shrimp and crab, and its production is second only to cellulose. Chitin is composed of a binary linear copolymer of 2-acetylamino-2-deoxy-β-D-glucopyranose and 2-amino-2-deoxy-β-D-glucopyranose. Chitin can be converted into a variety of products, including chitosan, chitosan oligosaccharides, carboxymethyl chitosan, N-acetylglucosamine, glucosamine, and carboxymethylglucosamine. Chitosan and its derivatives have a wide range of applications, including biomedical materials, health supplements, cosmetics, and food.

[0051] The cellulose derivative in the cleaning solution of the present invention removes CuO while the chitosan derivative forms a monomolecular adsorption layer on the Cu2O surface after the CuO film has been removed, which protects the underlying Cu. The chitosan derivative has an antioxidant effect and inhibits the further oxidation of Cu2O to CuO during the waiting time, thereby widening the process window and avoiding V bd The reduction of ,improves the reliability of the device.

[0052] The present invention's post-CMP cleaning solution for semiconductor chips eliminates the need for additional chelating agents, corrosion inhibitors, or surfactants. This is because the cellulose and chitosan derivatives contain polyhydroxy substances or organic carboxylic acids, which can chelate metal ions, inhibit metal corrosion, and reduce surface tension. Therefore, the present invention's post-CMP cleaning solution for semiconductor chips is naturally green, aligning with the concept of "green manufacturing."

[0053] Furthermore, the ultrapure water is deionized water with a resistance of at least 18 MΩ at 25°C.

[0054] Furthermore, the mass proportion of the ultrapure water is 70-95 parts, for example, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts or 95 parts.

[0055] Furthermore, the mass fraction of the ultrapure water is preferably 80-90 parts.

[0056] The substances used above are all well-known and commonly used substances and can be purchased through commercial channels.

[0057] Another object of the present invention is to disclose a method for preparing a cleaning solution for semiconductor chips after chemical mechanical polishing, comprising the following steps:

[0058] Firstly, a strong base and a weak base are added into ultrapure water and mixed evenly; then a cellulose derivative and a chitosan derivative are added and mixed evenly again to prepare a cleaning liquid for semiconductor chip after chemical mechanical polishing.

[0059] Furthermore, after uniform mixing, filtration is performed. The filtration is preferably performed using a 0.2 μm filter bag. Those skilled in the art may choose other forms of filtration methods, which will not be described in detail here.

[0060] Furthermore, the above preparation method is carried out at room temperature.

[0061] Furthermore, the stirring time and stirring speed during mixing are not particularly limited, as long as the system can be stirred uniformly.

[0062] Another object of the present invention is to disclose the use of a post-CMP cleaning solution for semiconductor chips. This cleaning solution is particularly suitable for cleaning contaminants from Cu wafers after CMP. This cleaning solution effectively removes organic and inorganic particulate contaminants generated after copper CMP. Furthermore, it is particularly effective at removing CuO from the surface, and reoxidation of the Cu surface is suppressed during subsequent waiting time.

[0063] Furthermore, the method for cleaning a Cu wafer after CMP with a cleaning liquid after chemical mechanical polishing of a semiconductor chip comprises the following steps: immersing the Cu wafer after CMP in the cleaning liquid after chemical mechanical polishing of a semiconductor chip at room temperature, or spraying the cleaning liquid after chemical mechanical polishing of a semiconductor chip onto the Cu wafer after CMP, rinsing with ultrapure water after immersion or spraying, and then drying with high-purity nitrogen, thereby completing the cleaning of the Cu wafer after CMP.

[0064] Furthermore, the soaking or spraying time is 2-5 minutes, for example, 2 minutes, 3 minutes, 4 minutes or 5 minutes.

[0065] Furthermore, the ultrapure water is deionized water with a resistance of at least 18 MΩ at 25°C.

[0066] The cleaning liquid for cleaning semiconductor chips after chemical mechanical polishing, the preparation method thereof, and the use thereof of the present invention have the following advantages compared with the prior art:

[0067] 1) The cellulose derivative in the cleaning solution of the present invention can effectively remove CuO formed by oxidation of Cu caused by the polishing solution, and the chitin derivative forms a monomolecular adsorption layer on the surface of Cu2O after the CuO film has been removed, which plays a protective role for the underlying Cu. In addition, the chitin derivative has an antioxidant effect, which inhibits the further oxidation of Cu2O to CuO during the waiting time, widens the process window, and avoids V bd The reduction of ,improves the reliability of the device.

[0068] 2) The cellulose derivatives in the cleaning solution of the present invention use 2,5-furandicarboxylic acid and 5-aminolevulinic acid at the same time. The corrosion of the carboxyl group and the chelation of the amino group work together to remove CuO faster. The simultaneous use of component A (chitosan derivatives chitosan oligosaccharide and / or carboxymethyl chitosan oligosaccharide) and component B (one or more of N-acetylglucose, glucosamine and carboxymethyl glucosamine) can achieve better reoxidation inhibition and corrosion inhibition. The reason is that the small molecule chitosan derivative can be embedded in the chitosan oligosaccharide and carboxymethyl chitosan oligosaccharide with higher molecular weight, so that a dense protective film is formed on the Cu surface.

[0069] 3) The cleaning solution of the present invention provides an alkaline environment, which can increase the electrostatic repulsion between the particle pollutants and the substrate, completely remove the abrasive particle pollution and metal particle pollution, and prevent the re-adsorption of the particles.

[0070] 4) The cleaning liquid of the present invention has simple ingredients and is green and environmentally friendly. It uses renewable biomass derivatives as additives, avoiding the addition of petroleum derivatives as additives, and plays the role of metal ion chelation, metal corrosion inhibition, and surface tension regulation.

[0071] 5) The cleaning solution of the present invention does not require the addition of additional chelating agents, corrosion inhibitors, or surfactants. This is because the cellulose and chitosan derivatives contain polyhydroxy substances or organic carboxylic acids, which can chelate metal ions, inhibit metal corrosion, and reduce surface tension. Therefore, the cleaning solution's ingredients are naturally green, in line with the concept of "green manufacturing."

[0072] Therefore, the cleaning solution of the present invention has very good application prospects and large-scale industrial promotion potential in the field of semiconductor chip cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] FIG1 is a scanning electron microscope image of an uncleaned Cu wafer after CMP at a magnification of 10,000 times.

[0074] FIG2 is a microscope picture of a Cu wafer after CMP cleaning using the cleaning solution prepared in Example 1, magnified 10,000 times.

[0075] FIG3 is an X-ray photoelectron spectrum of the Cu 2p orbital of the Cu wafer after CMP.

[0076] FIG4 is an X-ray photoelectron spectrum of Cu 2p orbitals after the CMP Cu wafer is cleaned with the cleaning solution prepared in Example 1.

[0077] FIG5 is an X-ray photoelectron spectrum of Cu 2p orbitals after the CMP Cu wafer is cleaned with the cleaning solution prepared in Comparative Example 1. DETAILED DESCRIPTION

[0078] The present invention is further described below with reference to the embodiments:

[0079] Examples 1-16

[0080] Examples 1-16 disclose a variety of cleaning solutions for semiconductor chips after chemical mechanical polishing. The components and weight ratios contained therein are shown in Table 1. The preparation method is as follows: at room temperature, a strong base and a weak base are added to ultrapure water and mixed evenly; then a cellulose derivative and a chitin derivative are added and mixed evenly again, and finally filtered using a 0.2μm filter bag to prepare a cleaning solution for semiconductor chips after chemical mechanical polishing.

[0081] Table 1 Components and weight ratios of cleaning solutions for semiconductor chips after chemical mechanical polishing in Examples 1-16

[0082] Comparative Examples 1-4

[0083] Comparative Examples 1-4 disclose a variety of cleaning solutions, the components and weight ratios of which are shown in Table 2. The preparation methods are the same as those of Example 1.

[0084] Table 2 Components and weight ratios of cleaning solutions of Comparative Examples 1-4

[0085] Performance test and description

[0086] The various properties of the above embodiments or comparative examples are tested as follows:

[0087] (1) CuO cleaning effect test

[0088] Figure 1 is a scanning electron microscope image of an unwashed Cu wafer after CMP at 10,000x magnification. Figure 1 shows the presence of numerous abrasive nano-silicon oxide particles on the surface of the polished Cu wafer. These particles are approximately 50 nm in size and appear either dispersed or aggregated.

[0089] Figure 2 is a microscope image at 10,000 times magnification of a Cu wafer after CMP cleaning using the cleaning solution prepared in Example 1. As can be seen from Figure 2, the Cu surface after cleaning with the cleaning solution in Example 1 is very clean, and the silicon oxide particles are substantially completely removed.

[0090] Figure 3 shows the X-ray photoelectron spectrum of the Cu 2p orbitals of the Cu wafer after CMP. Figure 3 shows that the Cu surface after CMP is oxidized and exists in two oxidation states: CuO and Cu2O. The binding energy of Cu(0) is at 932.695 eV, Cu(I) at 934.379 eV, and Cu(II) at 931.879 eV.

[0091] Figure 4 shows the X-ray photoelectron spectrum of the Cu 2p orbitals of a Cu wafer after CMP cleaning with the cleaning solution prepared in Example 1. Figure 4 shows that the cleaning method in Example 1 completely removes CuO from the Cu surface. In the XPS graph, the binding energy at 932.122 eV is for Cu(0), and at 934.443 eV is for Cu(I).

[0092] Figure 5 shows the X-ray photoelectron spectrum of Cu 2p orbitals after cleaning a Cu wafer after CMP with the cleaning solution prepared in Comparative Example 1. Figure 5 shows that the CuO on the Cu surface cannot be completely removed after cleaning using Comparative Example 1. In the XPS graph, the binding energy at 933.9 eV is for Cu(0), 935.5 eV for Cu(I), and 932.8 eV for Cu(II).

[0093] The percentage of Cu in different valence states can be obtained by XPS integration, as shown in Table 3:

[0094] Table 3 Percentage of Cu in different valence states after cleaning

[0095] As shown in Table 3, in Comparative Example 1, CuO removal was difficult to achieve without the addition of a cellulose derivative. However, in Examples 1-16, all of which incorporated cellulose derivatives, CuO was completely removed. However, in Comparative Example 3, due to the low addition of cellulose derivatives, CuO removal was also not achieved effectively, demonstrating that cellulose derivatives are essential for CuO removal. Comparative Examples 2 and 4, despite the addition of cellulose derivatives but without or at low levels of chitin derivatives, were still able to completely remove surface CuO, demonstrating that chitin derivatives are not essential for CuO removal and that cellulose derivatives are key to copper oxide removal.

[0096] (2) Reoxidation test of Cu surface during waiting period

[0097] In addition to CuO removal, another consideration is whether reoxidation of the Cu surface will occur during the waiting time. Table 4 shows the proportion of Cu in different valence states measured by XPS in the Examples and Comparative Examples after cleaning and polishing the Cu and then placing it in an atmospheric environment at 25°C.

[0098] Table 4 The proportion of Cu in different valence states in the atmospheric environment at 25℃

[0099] As shown in Table 4, the CuO growth of unwashed Cu or comparative example 2 without adding chitosan derivatives was greater than 2.5% during the initial 4-hour waiting time; while the growth of CuO in examples 1-16 and comparative example 1 with chitosan derivatives (without cellulose derivatives) was less than 0.35% during the initial 4-hour waiting time; comparative example 4 had a partial effect due to the addition of a small amount of chitosan derivatives, and the regeneration rate of surface CuO was between that of the examples and comparative example 2. It can be seen that the addition of chitosan derivatives can effectively inhibit the reoxidation of Cu surface. Therefore, the cleaning solution of the embodiment can effectively prevent V bd The reduction of ,improves the reliability of the device.

[0100] (3) Substrate corrosion rate test

[0101] As shown in Table 5, the corrosion strength of the cleaning solutions of Examples and Comparative Examples on the substrate was evaluated.

[0102] Table 5 Corrosion strength of cleaning fluid on substrate

[0103] As shown in Table 5, Examples 1-16 and Comparative Example 1, to which chitosan derivatives were added, exhibited relatively low etching rates for both metals and non-metals, while Comparative Examples 2 and 4, to which no chitosan derivatives were added or partial chitosan derivatives were added, exhibited relatively high substrate corrosion rates. This demonstrates that chitosan derivatives exhibit a strong inhibitory effect on substrate corrosion, a possible explanation being their polyhydroxy structure. The -OH and -NH2 groups contained in chitosan derivatives are electron-rich groups that can be adsorbed onto metal substrate surfaces with vacant orbitals, thereby inhibiting corrosion.

[0104] in:

[0105] 1. Cleaning method of Cu after CMP:

[0106] The polished Cu wafer was cut into 4*4 cm square samples, and then the cut wafer was placed in a cleaning solution at 25°C for cleaning, stirring while cleaning, with the speed set to 500 rpm. After 5 minutes, it was taken out, rinsed with pure water for 1 minute, and then blown dry with N2.

[0107] 2. Test of the proportion of Cu in different valence states on the surface of Cu wafer:

[0108] Cut the polished Cu wafer into 4x4cm square specimens. Then, place the wafer in a 25°C cleaning solution for cleaning, stirring while cleaning at 500 rpm. After 5 minutes, remove the wafer, rinse with pure water for 1 minute, and then blow dry with nitrogen. Use an X-ray photoelectron spectrometer to analyze the Cu surface before and after cleaning. If a waiting time is required, place the wafer in a 25°C ambient environment for a certain period of time before performing the XPS test.

[0109] 3. Test of substrate corrosion rate:

[0110] A precise quantitative test of the corrosion of copper, cobalt, tantalum nitride, tantalum, and silicon dioxide was conducted using a step profiler. The specific test method is as follows: a Si substrate (size 4×4 cm) coated with the above materials was immersed in a cleaning solution at 25°C for 60 minutes. The step profiler was used to measure the step height before and after immersion, and the corrosion rate was calculated. The corrosion rates of different cleaning solutions on the above substrates were investigated.

[0111] As described above, the present invention provides an example of the application of biomass-based derivatives in the field of microelectronic cleaning. More specifically, a method for preparing a cleaning solution after copper chemical mechanical polishing, its use, and a method for cleaning a Cu substrate after chemical mechanical polishing using the cleaning solution are provided. The cleaning solution provides an alkaline environment, improves the electrostatic repulsion between the particle pollutants and the substrate, can completely remove abrasive particle pollution and metal particle pollution, and preferably prevents the re-adsorption of particles. In addition, the cleaning solution has simple ingredients and is green and environmentally friendly. It uses renewable biomass derivatives as additives, avoids the addition of petroleum derivative additives, and plays the role of metal ion chelation, metal corrosion inhibition, and surface tension regulation. Cellulose derivatives can effectively remove CuO formed by Cu oxidation caused by polishing liquid, and chitin derivatives form a monomolecular adsorption layer on the Cu2O surface after the CuO film has been removed, protecting the underlying Cu and preventing Cu oxidation. The chitin derivatives have antioxidant effects, which inhibit the further oxidation of Cu2O to CuO during the waiting time, expand the process window, and avoid V bd Reduced, improved device reliability.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cleaning solution for semiconductor chips after chemical mechanical polishing, characterized in that: The composition includes the following components in mass proportion:

2. The cleaning solution for semiconductor chips after chemical mechanical polishing according to claim 1, characterized in that: The strong base is an organic strong base and / or an inorganic strong base.

3. The cleaning solution for semiconductor chips after chemical mechanical polishing according to claim 1, characterized in that: The weak base is an organic alcohol amine.

4. The cleaning solution for semiconductor chips after chemical mechanical polishing according to claim 1, characterized in that: The cellulose derivative is one or more of 2,5-furandicarboxylic acid, levulinic acid and 5-aminolevulinic acid.

5. The cleaning solution for semiconductor chips after chemical mechanical polishing according to claim 1, characterized in that: The cellulose derivatives are 2,5-furandicarboxylic acid and 5-aminolevulinic acid.

6. The cleaning solution for semiconductor chips after chemical mechanical polishing according to claim 1, characterized in that: The chitosan derivative is one or more of chitosan oligosaccharide, carboxymethyl chitosan, N-acetylglucose, glucosamine and carboxymethyl glucosamine.

7. The cleaning solution for semiconductor chips after chemical mechanical polishing according to claim 1, characterized in that: The chitosan derivative comprises an A component and a B component, wherein the A component is chitosan oligosaccharide and / or carboxymethyl chitosan; and the B component is one or more of N-acetylglucose, glucosamine and carboxymethylglucosamine.

8. A method for preparing a cleaning solution for semiconductor chips after chemical mechanical polishing according to any one of claims 1 to 7, characterized in that: The following steps are involved: Firstly, a strong base and a weak base are added into ultrapure water and mixed evenly; then a cellulose derivative and a chitosan derivative are added and mixed evenly again to prepare a cleaning liquid after chemical mechanical polishing of a semiconductor chip.

9. Use of a cleaning liquid after copper chemical mechanical polishing in the field of cleaning semiconductor chips.

10. The method for cleaning a Cu wafer after CMP using a cleaning solution after chemical mechanical polishing of a semiconductor chip according to claim 9, characterized in that: The method comprises the following steps: at room temperature, immersing the Cu wafer after CMP into a cleaning solution after chemical mechanical polishing of a semiconductor chip, or spraying the cleaning solution after chemical mechanical polishing of a semiconductor chip onto the Cu wafer after CMP, rinsing with ultrapure water after immersion or spraying, and then drying with high-purity nitrogen, thereby completing the cleaning of the Cu wafer after CMP.

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