Chemical mechanical polishing composition and polishing method for polycrystalline silicon
By providing a chemical mechanical polishing composition containing colloidal silicon dioxide, nitrogen-containing compounds and organic acids, the problem of low polishing rate of polycrystalline silicon in the prior art is solved, and efficient polishing of polycrystalline silicon and other interlayer media is achieved, ensuring the planarization of interlayer media and the smooth progress of subsequent processing.
Patent Information
- Application Number
- CN202510476194.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-07-01
AI Technical Summary
In the prior art, the polishing rate of the acid polishing composition on polycrystalline silicon is low, resulting in insufficient polishing rate selection ratio between polycrystalline silicon and silicon nitride, polycrystalline silicon and silicon oxide during the interlayer dielectric planarization process, affecting the subsequent processing of metal layers and device performance.
A chemical mechanical polishing composition for polycrystalline silicon is provided, including colloidal silica abrasive particles, hydroxyl-containing nitrogen-containing compounds (such as tris(2-hydroxyethyl)methyl ammonium hydroxide) as organic bases, organic acids and chelating agents, adjusting the pH value of the composition between 1.5 and 3.0.
The polishing composition significantly improves the polishing rate of polycrystalline silicon under an acidic environment, increases the polishing rate selection ratio between polycrystalline silicon and silicon nitride, polycrystalline silicon and silicon oxide, so that the interlayer dielectric can be completely flattened, facilitates subsequent processing of metal layers, and improves device performance.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a chemical mechanical polishing composition and a polishing method for polishing an interlayer dielectric such as polysilicon. Background Art
[0002] The dielectric layer is an electrically insulating layer between a silicon device and a metal layer or between metal layers. The most widely used ILD (Interlayer Dielectric) in CMP (Chemical Mechanical Polishing) includes silicon dioxide, borophosphosilicate glass, phosphosilicate glass, silicon nitride, polysilicon, etc.
[0003] The flatness of the interlayer dielectric will affect the subsequent manufacture of the metal layer. Since the deposited dielectric layer covers the previously manufactured device and undulates more severely with the surface height, it is difficult for the subsequent lithography process to focus. Therefore, there will be too many stacked layers that need to be removed by CMP. There is no obvious stop point in this process, and the thickness of the film to be removed is used as the standard to meet the flatness requirement.
[0004] Silicon dioxide is the most common interlayer dielectric, which is used as an insulating film or an isolation layer. With the increasing complexity of the integrated circuit process, the isolation layer will involve a variety of different materials, such as polysilicon and silicon nitride. When surface planarization is carried out by chemical mechanical polishing (CMP), the selection ratio of the removal rates between different silicon materials has a great impact on the planarization effect. Generally, there are requirements for the selectivity of silicon oxide / silicon nitride. As the process complexity increases, there are gradually requirements for the polishing rate of polysilicon, and a higher polishing rate of polysilicon is needed. However, generally, the polishing rate of polysilicon by an acidic polishing composition is very low.
[0005] There is an urgent need to explore a new chemical mechanical polishing composition for polysilicon to solve the problems existing in the prior art. Summary of the Invention
[0006] In view of the problems existing in the prior art, the present invention provides, in a first aspect, a chemical mechanical polishing composition for polysilicon, the polishing composition comprising colloidal silica abrasive particles, an organic base, an organic acid, a chelating agent, and water, wherein the organic base is a nitrogen-containing compound with a hydroxyl group;
[0007] The hydroxyl content of the nitrogen-containing compound is 10 - 21 mmol / g;
[0008] The polishing composition has a pH of 1.5 - 3.0;
[0009] Furthermore, the polishing composition contains about 0.01 wt% to about 1.0 wt% of the organic base;
[0010] Further, the nitrogen-containing compound includes one or a combination of more than one of ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, and tris(2-hydroxyethyl)methylammonium hydroxide;
[0011] Preferably, the nitrogen-containing compound is tris(2-hydroxyethyl)methylammonium hydroxide;
[0012] Further, the number of covalent hydroxyl groups of the nitrogen-containing compound is 2 to 3, and the hydroxyl content of the nitrogen-containing compound is 16 to 18 mmol / g;
[0013] Further, the content of the colloidal silica in the polishing composition is about 5% by weight to about 30% by weight;
[0014] Further, the Zeta potential of the colloidal silica is -15 to -55 mV;
[0015] Preferably, the Zeta potential of the silica is -40 to -55 mV;
[0016] The average particle size of the colloidal silica is 20 to 150 nm;
[0017] Preferably, the average particle size of the colloidal silica is 35 to 80 nm;
[0018] Further, the organic acid includes one or a combination of more than one of formic acid, acetic acid, propionic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, sulfonic acid, and organic phosphonic acid;
[0019] Further, the organic acid includes one or a combination of more than one of fumaric acid, maleic acid, and malonic acid;
[0020] Further, the chelating agent includes one or a combination of more than one of ethylenediaminetetraacetic acid, iminodiacetic acid, nitrilotriacetic acid, ethylenediaminedisuccinic acid, and aminophosphonic acid;
[0021] The second aspect of the present invention provides a method for polishing a substrate, including:
[0022] (i) Providing a substrate;
[0023] (ii) Providing a polishing pad;
[0024] (iii) Providing the chemical mechanical polishing composition as described in the first aspect of the present invention;
[0025] (iv) Bringing the substrate into contact with the polishing pad and the chemical mechanical polishing composition; and
[0026] (v) Moving a polishing pad and a chemical mechanical polishing composition relative to a substrate to grind at least a portion of the substrate to polish the substrate.
[0027] Advantageous effects:
[0028] The present invention provides a chemical mechanical polishing composition for polysilicon, which can improve the grinding rate of polysilicon in an acidic environment, increase the polishing rate selectivity between polysilicon and silicon nitride, and between polysilicon and silicon oxide, enable the interlayer dielectric to be completely planarized, facilitate the processing of subsequent metal layers, and improve device performance. Specific embodiments
[0029] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.
[0030] The present invention provides a chemical mechanical polishing composition for polysilicon, and the polishing composition includes abrasive particles, an organic base, an organic acid, a chelating agent, and water.
[0031] Abrasive particles
[0032] In the present invention, the abrasive particles are colloidal silica, which can be commercially available. Examples include, but are not limited to, a series of abrasive particles produced by Fuso Corporation: any one or a combination of PL-1, PL-2, PL-3, PL-5, and PL-6; or prepared by various methods, including widely used commercial methods, such as methods or ion exchange methods and other preparation methods well-known to those skilled in the art.
[0033] The abrasive particles can be present in the polishing composition in any suitable amount. If the polishing composition of the present invention contains too few abrasive particles, the removal rate of the composition is too low. On the contrary, if the polishing composition contains too many abrasive particles, the polishing composition may be over-polished, the cost increases, and the stability performance is poor. The polishing composition may contain about 30 wt% or less of colloidal silica abrasive particles, for example, about 25 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, about 5 wt% or less, about 4 wt% or less, about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.9 wt% or less, about 0.8 wt% or less, about 0.7 wt% or less, about 0.6 wt% or less, or about 0.5 wt% or less of colloidal silica abrasive. Additionally, the polishing composition may contain about 5 wt% or more of silica abrasive, for example, about 6 wt% or more, about 8 wt% or more, 10 wt% or more, about 15 wt% or more, about 20 wt% or more, about 25 wt% or more, about 30 wt% or more of colloidal silica abrasive. Therefore, when appropriate, the polishing composition may contain an amount of colloidal silica abrasive particles defined by any two of the foregoing endpoints.
[0034] The colloidal silica can have any suitable average size (i.e., average particle diameter). If the average abrasive particle size is too small, the polishing composition does not have sufficient removal rate. On the contrary, if the average abrasive particle size is too large, the polishing composition may cause undesirable polishing, such as causing substrate defects.
[0035] Therefore, the colloidal silica abrasive particles can have an average particle size of about 20 nm or greater, for example, about 30 nm or greater, about 40 nm or greater, about 50 nm or greater, about 60 nm or greater, about 70 nm or greater, about 80 nm or greater, about 100 nm or greater, or about 150 nm or greater. Additionally, the colloidal silica abrasive particles can have an average particle size of about 150 nm or less, for example, about 140 nm or less, about 130 nm or less, about 120 nm or less, about 100 nm or less, about 80 nm or less, about 40 nm or less, or about 20 nm or less. The silica abrasive can have an average particle size defined by any two of the foregoing endpoints. Preferably, the average particle diameter of the colloidal silica abrasive particles is 35 - 80 nm.
[0036] The colloidal silica can have negatively charged groups, so as to obtain abrasive particles with a Zeta potential of -15 to -55 mV. Preferably, the Zeta potential of the silica is -40 to -55 mV.
[0037] Negatively charged abrasive particles can be obtained by any suitable method that provides negative charges to the abrasive particles. Generally, the surface of the abrasive particles is covered by grafting to make them negatively charged. The specific method is as follows: adjust the pH of the abrasive particles to 9.0 with ammonia water, heat to 40 °C, dropwise add mercaptopropyltrimethoxysilane, keep warm for 1 h, then distill at normal pressure with a constant liquid level until the top temperature of the tower reaches 100 °C, and filter to obtain negatively charged abrasive particles.
[0038] By controlling the ratio of the mass of mercaptopropyltrimethoxysilane to the mass of the abrasive particles within the range of 0.2% to 1.8%, abrasive particles with a Zeta potential of -10 to -65 mV can be obtained. It can be cited that when the ratio of the mass of mercaptopropyltrimethoxysilane to the mass of the abrasive particles is 0.2%, the Zeta potential of the abrasive particles is -10 mV; when the ratio is 0.3%, the Zeta potential of the abrasive particles is -15 mV; when the ratio is 0.5%, the Zeta potential of the abrasive particles is -20 mV; when the ratio is 0.8%, the Zeta potential of the abrasive particles is -35 mV; when the ratio is 1.0%, the Zeta potential of the abrasive particles is -40 mV; when the ratio is 1.2%, the Zeta potential of the abrasive particles is -50 mV; when the ratio is 1.3%, the Zeta potential of the abrasive particles is -55 mV; when the ratio is 1.8%, the Zeta potential of the abrasive particles is -65 mV.
[0039] Organic base
[0040] The polishing composition further includes an organic base, which is a nitrogen-containing compound with a hydroxyl group. The nitrogen-containing compounds include one or more combinations of ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, and tris(2-hydroxyethyl)methylammonium hydroxide, which can be obtained commercially or prepared by various methods, including widely used commercial methods. The preparation of ethanolamine, diethanolamine, and triethanolamine is mainly based on the reaction of ethylene oxide and ammonia. By adjusting the reaction conditions (such as the ratio of ethylene oxide to ammonia, temperature, and pressure) and using catalysts, the ratio of different ethanolamines in the product can be controlled; N-methyldiethanolamine can be obtained by the ethylene oxide method, the methylation method of ethanolamine and methanol, or the catalytic hydrogenation method of ethanolamine and formaldehyde; tris(2-hydroxyethyl)methylammonium hydroxide can be obtained through a series of quaternization reactions, hydroxyethylation reactions, and neutralization reactions, etc.
[0041] In the presence of an organic base, an interlayer dielectric such as polysilicon is more easily oxidized to form silicon dioxide or silicate ions, and thus is more easily removed by abrasive particles in the polishing composition; basic groups in the organic base (such as primary amines, secondary amines, etc.) can chemically react with silicon atoms on the polysilicon surface to break the covalent bonds of silicon. For example, organic bases such as triethanolamine can promote the hydrolysis reaction on the silicon surface by providing hydroxide ions (OH-), breaking the bonds between silicon atoms to form soluble silicate; organic bases can change the chemical properties of the polysilicon surface. For example, organic bases such as triethanolamine can change the polysilicon surface from hydrophobic to hydrophilic. This surface modification helps the polishing liquid better wet the silicon surface and improve the polishing efficiency.
[0042] The hydroxyl content generally refers to covalently bonded hydroxyl groups (-OH) in a molecule, and ionic OH- (such as OH- in NaOH) is not included. The hydroxyl content of a nitrogen-containing compound is calculated according to the following formula:
[0043]
[0044] where n is the number of covalent hydroxyl groups, and M is the molar mass of the compound in g / mol.
[0045] Limiting the hydroxyl content of the nitrogen-containing compound within the range of 10 - 21 mmol / g, preferably, the hydroxyl content of the nitrogen-containing compound is 16 - 18 mmol / g, and the number of covalent hydroxyl groups of the nitrogen-containing compound is 2 - 3, which is beneficial to the polishing of polysilicon, improves the polishing rate selectivity ratio between polysilicon and other interlayer dielectrics, and the planarization degree is improved. Further preferably, the nitrogen-containing compound is tris(2-hydroxyethyl)methylammonium hydroxide.
[0046] The organic base can be present in the polishing composition in any suitable amount. If the organic base of the present invention contains too little organic base, the removal rate of the interlayer dielectric, especially polysilicon, is too low. On the contrary, if the polishing composition contains too much organic base, the polysilicon polishing rate may increase slowly while the cost increases significantly, resulting in a poor cost performance. The polishing composition may contain about 1.0% by weight or less of the organic base, for example, about 0.9% by weight or less, about 0.8% by weight or less, about 0.7% by weight or less, about 0.6% by weight or less, about 0.5% by weight or less, about 0.4% by weight or less, about 0.3% by weight or less, about 0.2% by weight or less, about 0.1% by weight or less, about 0.08% by weight or less, about 0.06% by weight or less, about 0.04% by weight or less, about 0.02% by weight or less, or about 0.01% by weight or less of the organic base. Additionally, the polishing composition may contain about 0.01% by weight or more of the organic base, for example, about 0.02% by weight or more, about 0.05% by weight or more, 0.07% by weight or more, about 0.10% by weight or more, about 0.20% by weight or more, about 0.40% by weight or more, about 0.60% by weight or more, about 0.80% by weight or more, about 1.0% by weight or more of the organic base. Therefore, when appropriate, the polishing composition may contain an amount of the organic base defined by any two of the foregoing endpoints.
[0047] Organic acid
[0048] In the present invention, the polishing composition further includes an organic acid, and the organic acid includes one or more combinations of formic acid, acetic acid, propionic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, sulfonic acid, and organic phosphonic acid. Preferably, the organic acid includes one or more combinations of fumaric acid, maleic acid, and malonic acid.
[0049] The organic acid can dissolve the oxide layer and silicon atoms on the surface of polysilicon through chemical corrosion, thereby increasing the removal rate of the material. The hydrogen ions (H +) can react with the oxide layer (SiO2) on the silicon surface to promote its dissolution. For example, organic acids such as citric acid can displace the metal impurity cations on the silicon surface through proton exchange, and at the same time, the organic acid root anions can adsorb on the silicon surface to further promote the dissolution of silicon. The organic acid root anions can form complexes with the metal impurities or silicon atoms on the polysilicon surface, and these complexes are more easily removed by the abrasive particles in the polishing liquid. For example, citric acid and oxalic acid can effectively dissolve silicon through complexation, thereby destroying the crystal structure of polysilicon and increasing its reactivity. Organic acids can also act as pH regulators to adjust the pH value of the polishing liquid to the acidic range, thereby optimizing the chemical environment of the polishing liquid.
[0050] The organic acid can be present in the polishing composition in any suitable amount as long as it can ensure that the pH value of the polishing composition is within a suitable range.
[0051] Chelating agent
[0052] In the present invention, the chelating agent includes one or more combinations of ethylenediaminetetraacetic acid, iminodiacetic acid, nitrilotriacetic acid, ethylenediaminedisuccinic acid, and aminophosphonic acid.
[0053] The chelating agent promotes its dissolution and removal by chemically interacting with the oxide layer or silicon atoms on the polysilicon surface; it can improve the dispersibility of the abrasive particles in the polishing liquid, prevent particle agglomeration, thereby improving the stability and uniformity of the polishing liquid; it can reduce the mechanical damage to the silicon wafer surface during the polishing process, thereby reducing the surface roughness; it can increase the selective removal rate of the polishing liquid for polysilicon and other materials (such as silicon dioxide, silicon nitride, etc.).
[0054] The chemical mechanical polishing composition of the present invention optionally further comprises one or more additives. Illustrative additives include bactericides, scale inhibitors, and dispersants. When present, the bactericide can be any suitable bactericide and can be present in the polishing composition in any suitable amount. A suitable bactericide is an isothiazolinone bactericide. Generally, the polishing composition contains about 1 ppm to about 50 ppm of bactericide, preferably about 10 ppm to about 20 ppm of bactericide.
[0055] pH of the polishing composition
[0056] A chemical mechanical polishing composition may comprise one or more compounds capable of adjusting the pH of the polishing composition. The pH of the polishing composition can be adjusted using any suitable compound that can adjust the pH of the polishing composition. Desirably, the pH adjusting compound is water-soluble and compatible with other components of the polishing composition, such as the organic acids mentioned above. Generally, the chemical mechanical polishing composition has a pH of about 1.5 to about 7.0 at the point of use (e.g., a pH of about 1.5 to about 6.0, about 1.5 to about 5.0, about 2.0 to about 7.0, about 2.0 to about 6.0, about 2.0 to about 5.0, about 3.0 to about 6.0). Preferably, the chemical mechanical polishing composition has a pH of about 1.5 to about 3.0 at the point of use.
[0057] By setting the pH within the above range, the polishing composition can achieve high selective removal of different materials, which is particularly important for the interlayer dielectric polishing of polysilicon, silicon nitride, and silicon oxide. Acidic polishing compositions generally have a higher polishing rate and can quickly remove materials such as polysilicon.
[0058] The polishing composition in the present invention can be applied to the chemical mechanical polishing of interlayer dielectrics: during the polishing process, the polishing composition is continuously dropped onto the polishing pad, and the substrate containing the interlayer dielectric is tightly pressed against the high-speed rotating polishing pad. Organic bases in the polishing composition react with the surface of the substrate to form an easily removable layer. At the same time, the chelating agent binds to the reaction product and dissolves it in the polishing composition to prevent it from accumulating on the surface of the substrate. The abrasive particles in the polishing composition mechanically abrade the surface of the substrate under pressure and rotation to remove the easily removable layer generated by the chemical reaction, exposing a new surface. The new surface then becomes an easily removable layer again, and so on, until the surface of the substrate is finally flattened. As the polishing progresses, it is necessary to regularly replenish fresh polishing composition to maintain the concentration and performance of the polishing composition.
[0059] The above and other advantages of the present invention can be better understood through the following examples, but the following examples are not intended to limit the scope of the present invention.
[0060] Examples
[0061] The following examples are given to illustrate the present invention, but the present invention is not limited by the following examples.
[0062] Synthesis Example 1
[0063] Ethanolamine: Ethylene oxide and ammonia water were mixed at a molar ratio of 1:3 and reacted in a tubular reactor. The reaction temperature was 50 °C, the pressure was 2.5 Mpa, and the reaction time was 4 h. After the reaction, the mixed solution was dehydrated and concentrated at 95 °C. The concentrated mixed solution was fed into a vacuum distillation column and vacuum distilled under the condition of a pressure of 10 kPa. The fractions were intercepted according to different boiling points, and the fraction with a boiling point of 168 - 174 °C was collected to obtain ethanolamine with a purity of 99%.
[0064] Synthesis Example 2
[0065] Diethanolamine: Ethylene oxide and ammonia water were mixed at a molar ratio of 2:1 and reacted in a tubular reactor. The reaction temperature was 80 °C, the pressure was 5.0 Mpa, and the reaction time was 6 h. After the reaction, the mixed solution was dehydrated and concentrated at 95 °C. The concentrated mixed solution was fed into a vacuum distillation column and vacuum distilled under the condition of a pressure of 10 kPa. The fraction with a boiling point of 268 - 274 °C was collected to obtain diethanolamine with a purity of 99%.
[0066] Synthesis Example 3
[0067] Triethanolamine: Ethylene oxide and ammonia water were mixed at a molar ratio of 3:1 and reacted in a tubular reactor. The reaction temperature was 100 °C, the pressure was 5.0 Mpa, and the reaction time was 8 h. After the reaction, the mixed solution was dehydrated and concentrated at 95 °C. The concentrated mixed solution was fed into a vacuum distillation column and vacuum distilled under the condition of a pressure of 10 kPa. The fraction with a boiling point of 358 - 364 °C was collected to obtain triethanolamine with a purity of 99%.
[0068] Synthesis Example 4
[0069] N-Methyldiethanolamine: 83.1 g of methanol, 62.6 g of nitromethane, 1.5 g of catalyst, 4.0 g of dichloromethane, and 105 g of paraformaldehyde with a mass fraction of 95% were successively added to a reaction kettle, and the mixture was stirred and gradually heated to 45 °C for reaction for 3 h. After the reaction was completed, the temperature was lowered to 30 °C, and the pH was adjusted to 4.5 with hydrochloric acid; 650 mol of methanol, 10 mol of dichloromethane, and 12 g of Raney nickel were added. The mixture was purged with nitrogen and hydrogen 4 - 5 times, the stirrer was started, and the temperature was slowly raised. Hydrogen was introduced, and the temperature was raised to 40 °C, and the reaction was carried out at a hydrogen pressure of 2.5 Mpa for 2.5 h. After the reaction was completed, recrystallization treatment was carried out 3 times, and vacuum drying was carried out to obtain N-methyldiethanolamine.
[0070] Synthesis Example 5
[0071] Tri(2-hydroxyethyl)methylammonium hydroxide: 75.83 kg of liquefied trimethylamine with a purity of 99% and 105.24 kg of water were added to a reaction kettle to obtain an aqueous solution containing trimethylamine, and the temperature was raised while stirring; when the temperature reached 60 °C, 56.44 kg of 99% liquefied ethylene oxide was added and the reaction was carried out for 2 h. After the reaction ended, recrystallization was carried out 3 times, and vacuum drying was performed to obtain tri(2-hydroxyethyl)methylammonium hydroxide.
[0072] The hydroxyl content of the nitrogen-containing compound is calculated according to the following formula:
[0073]
[0074] where n is the number of covalent hydroxyl groups, and M is the molar mass of the compound, with the unit of g / mol.
[0075] The hydroxyl contents of ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, and tri(2-hydroxyethyl)methylammonium hydroxide were calculated respectively and are shown in Table 1:
[0076] Table 1
[0077]
[0078] As shown in Table 1, tri(2-hydroxyethyl)methylammonium hydroxide has a total of 4 hydroxyl groups, but 1 of them is a free hydroxyl group. Therefore, only 3 belong to covalent hydroxyl groups. Tetramethylammonium hydroxide has a total of 4 hydroxyl groups, and all 4 of these hydroxyl groups are free hydroxyl groups. Therefore, the number of covalent hydroxyl groups is 0.
[0079] Table 2 shows the components and contents of the chemical mechanical polishing compositions for polysilicon in the examples and comparative examples of the present invention. A chemical mechanical polishing liquid was prepared by simply stirring and mixing 0.01 wt% of a chelating agent and the formulation shown in Table 2, and an organic acid was added dropwise and mixed evenly until the set pH was reached, and the balance was made up to 100% with water to obtain each example and comparative example of the present invention. Polishing liquids were prepared according to the components and ratios shown in Table 2:
[0080] Table 2
[0081]
[0082]
[0083] Polishing experiments were carried out using the polishing compositions in the above-mentioned examples and comparative examples. The polishing conditions were as follows: using an LK (CMP machine), a DH3002H polishing pad (purchased from DINGLONG Co., Ltd.), a pressure of 2.0 psi, a polishing base / polishing head rotation speed of 93 / 87 rpm, and a polishing liquid flow rate of 300 mL / min. A substrate containing polysilicon, silicon oxide, and silicon nitride was polished. A surface defect detector (KLA SP7) was used to detect scratch data, and the evaluation results are shown in Table 3.
[0084] Table 3
[0085]
[0086]
[0087] It should be noted that, based on the explanations and elaborations in the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above-mentioned embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some equivalent modifications and changes to the present invention should also be within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the invention.
Claims
1. A chemical mechanical polishing composition for polycrystalline silicon, characterized in that: The polishing composition comprises: (i) colloidal silica abrasive particles; (ii) an organic base, wherein the organic base is a nitrogen-containing compound containing a hydroxyl group, and the hydroxyl content of the nitrogen-containing compound is 10 to 21 mmol / g; (iii) organic acids; (iv) chelating agents; (v) water; The polishing composition has a pH of 1.5 to 3.
0.
2. The chemical mechanical polishing composition for polycrystalline silicon according to claim 1, characterized in that: The polishing composition comprises about 0.01 wt.% to about 1.0 wt.% of an organic base.
3. The chemical mechanical polishing composition for polycrystalline silicon according to claim 1, characterized in that: The nitrogen-containing compound includes one or more combinations of ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, and tris(2-hydroxyethyl)methylammonium hydroxide. Preferably, the nitrogen-containing compound is tris(2-hydroxyethyl)methylammonium hydroxide.
4. The chemical mechanical polishing composition for polycrystalline silicon according to claim 3, characterized in that: The number of covalent hydroxyl groups of the nitrogen-containing compound is 2 to 3, and the hydroxyl content of the nitrogen-containing compound is 16 to 18 mmol / g.
5. The chemical mechanical polishing composition for polycrystalline silicon according to claim 1, characterized in that: The colloidal silica is present in an amount of about 5 wt. % to about 30 wt. % in the polishing composition.
6. The chemical mechanical polishing composition for polycrystalline silicon according to claim 5, characterized in that: The Zeta potential of the colloidal silica is -15 to -55 mV, preferably -40 to -55 mV; the average particle size of the colloidal silica is 20 to 150 nm, preferably 35 to 80 nm.
7. The chemical mechanical polishing composition for polycrystalline silicon according to claim 1, characterized in that: The organic acid includes one or more combinations of formic acid, acetic acid, propionic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, sulfonic acid, and organic phosphonic acid.
8. The chemical mechanical polishing composition for polycrystalline silicon according to claim 7, characterized in that: The organic acid includes one or more combinations of fumaric acid, maleic acid and malonic acid.
9. The chemical mechanical polishing composition for polycrystalline silicon according to claim 1, characterized in that: The chelating agent includes one or more combinations of ethylenediaminetetraacetic acid, iminodiacetic acid, nitrilotriacetic acid, ethylenediaminedisuccinic acid, and aminophosphoric acid.
10. A method for polishing a substrate, characterized in that: include: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing the chemical mechanical polishing composition according to claim 1; (iv) contacting the substrate with a polishing pad and a chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the substrate to polish the substrate.