Silicon wafer polishing solution for chemical mechanical polishing and preparation method thereof
By using polymer polymers and specific polymers in the polishing liquid, combining silicon sols, complexing agents and nitrogen-containing substances, the problem that existing polishing liquids are difficult to simultaneously increase the polishing rate, reduce surface roughness and particle residues, achieving a low-foam or no-foam polishing effect, ensuring high quality and high precision of the silicon wafer surface.
Patent Information
- Application Number
- CN202510081955.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2025-05-30
AI Technical Summary
The existing polishing liquids are difficult to simultaneously increase the polishing rate of the silicon wafer, reduce surface roughness and particle residues, and there is an impact of foam on polishing.
A new polishing liquid is prepared by using polymer polymers with the formula R-(-O-CH2-CH2-)n-R1, combined with a silicon sol, a complexing agent and nitrogen-containing substances. The polishing liquid does not contain defoaming agent, and is low in foam or no foam, reducing the impact of foam on polishing.
It is achieved without increasing foam, improving the polishing rate, reducing the roughness and particle residue on the surface of the silicon wafer, ensuring that the surface of the silicon wafer is super hydrophilic, avoiding corrosion, and obtaining a high-quality and high-precision polished surface.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of polishing liquids, and particularly to a silicon wafer polishing liquid for chemical mechanical polishing and a preparation method thereof. Background Art
[0002] Semiconductor materials mainly made of silicon have become indispensable basic functional materials in industrial fields such as microelectronics and solar cells. Single crystal silicon wafers can be made into various semiconductor devices, which are widely used in science and technology, industry, and daily life, and play an important role in the national economy and military industry.
[0003] The surface polishing of silicon wafers is crucial in silicon wafer processing. Its processing accuracy directly affects indicators such as the performance and qualification rate of IC chips. Among them, the surface quality after polishing is an important evaluation index of the polishing liquid. In particular, the surface roughness and particle residue after polishing will directly affect the next processing of the silicon wafer. Existing polishing liquids can only solve the problem of polishing rate or whether there are particle residues on the surface singly, and cannot comprehensively solve problems such as polishing rate, surface roughness, and whether the silicon wafer surface is corroded. Summary of the Invention
[0004] To solve the above problems, a first aspect of the present invention provides a polishing liquid. Using a high molecular polymer and a polymer with the molecular formula R-(-O-CH 2 -CH 2 -) n -R 1 effectively reduces the surface roughness of the silicon wafer after polishing and forms a super-hydrophilic surface on the polished surface of the silicon wafer after polishing, reduces particle residue, and at the same time, under the premise that the system does not contain a defoaming agent, has low foam or no foam, effectively reducing the impact of foam on polishing, and it is easier to obtain a silicon wafer with a high-quality surface.
[0005] A silicon wafer polishing liquid for chemical mechanical polishing includes the following components:
[0006] Silica sol: 5-20 wt%;
[0007] Complexing agent: 0-1 wt%, not including 0 wt%;
[0008] Nitrogen-containing substances: 0.5-2 wt%;
[0009] High molecular polymer: 0.01-0.1 wt%;
[0010] Polymer with the molecular formula R-(-O-CH 2 -CH 2 -) n -R 1 : 0.001-0.1 wt%;
[0011] Water: the balance.
[0012] Silica sol
[0013] The silica sol is selected from nano-scale silica sols prepared by the sol-gel method. Preferably, the average primary particle size of the silica sol is 1-100 nm, and the average secondary particle size is 1-200 nm; more preferably, the average primary particle size of the silica sol is 20-50 nm, and the average secondary particle size is 50-100 nm. Even more preferably, the average primary particle size of the silica sol is 40 nm, and the average secondary particle size is 70 nm. In this application, the primary particle size refers to the particle size of a single small crystal grain, and the secondary particle size refers to the particle size formed by the aggregation of small crystal grains to form larger secondary particles; the testing methods for the primary particle size include BET, titration, etc.; the testing methods for the secondary particle size include electron microscopy, laser diffraction, etc.
[0014] Using a silica sol with an average primary particle size of 1-100 nm and an average secondary particle size of 1-200 nm causes extremely little damage to the surface of the polished workpiece, can effectively reduce scratches on the surface of the silicon wafer, and is especially suitable for the fine polishing of silicon wafers with high surface quality requirements; moreover, it can better cooperate with complexing agents, nitrogen-containing substances, etc. in the polishing liquid to play a synergistic effect.
[0015] Preferably, the concentration of the silica sol is 10 wt%.
[0016] Complexing agent
[0017] The complexing agent is selected from one or more of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), N-hydroxyethyl ethylenediamine triacetic acid (HEDTA), ethylene glycol-bis-(β-aminoethyl ether)-N,N-tetraacetic acid (EGTA), hydroxyethylidene-1,1-diphosphonic acid (HEDP), aminotrimethylenephosphonic acid (ATMP), diethylenetriamine pentamethylenephosphonic acid (HTPMP), triethylenetetramine hexamethylenephosphonic acid (TETHMP), bis(1,6-hexylene)triamine pentamethylenephosphonic acid (BNHMTPMP), polyamino polyether poly(methylene phosphonic acid) (PAPEMP). More preferably, it is ethylenediaminetetraacetic acid (EDTA).
[0018] Preferably, the concentration of the complexing agent is 0.02 wt%.
[0019] Nitrogen-containing substances
[0020] The nitrogen-containing substances are selected from at least one of hydroxylamine-containing compounds, non-hydroxylamine-containing compounds, and heterocyclic nitrogen-containing compounds.
[0021] Examples of the hydroxylamine-containing compounds include hydroxyethyl ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, etc.
[0022] Examples of the hydroxylamine-free substances include triethylamine, trimethylamine, ethylenediamine, etc.
[0023] The heterocyclic nitrogen-containing compounds include one or more of piperazine and its derivatives, imidazole and its derivatives, pyrazine and its derivatives, oxazoline and its derivatives, quinoline and its derivatives, pyridine and its derivatives.
[0024] Preferably, the nitrogen-containing substance is selected from hydroxylamine-containing compounds or heterocyclic nitrogen-containing compounds; more preferably, the nitrogen-containing substance is selected from hydroxyethyl ethylenediamine and / or N-methylpiperazine; most preferably, it is N-methylpiperazine.
[0025] Preferably, the concentration of the nitrogen-containing substance is 1 wt%.
[0026] In this application, N-methylpiperazine participates in the chemical reaction process of polishing, affecting the rate and course of the chemical reaction. It can interact with the silicon surface, the polymer in the polishing liquid, etc., to adjust the rate and manner of the removal of the surface material of the silicon wafer, making the polishing process more efficient and more likely to obtain a high-quality and high-precision polished surface, meeting the strict requirements for parameters such as surface roughness when the silicon wafer is used in semiconductor and other fields.
[0027] Polymer
[0028] The polymer includes at least one of cellulose and its derivatives, amide group-containing polymers, and polyvinyl alcohol.
[0029] The cellulose and its derivatives include at least one of cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose. Preferably, the cellulose and its derivatives are hydroxyethyl cellulose.
[0030] The amide group-containing polymer is at least one of polyvinylpyrrolidone (abbreviation: PVP), PVA-PVP copolymer.
[0031] Preferably, the concentration of the polymer is 0.01 - 0.1 wt%, preferably 0.03 wt%.
[0032] The polymer with the formula R-(-O-CH 2 -CH 2 -) n -R 1
[0033] The polymer with the formula R-(-O-CH 2 -CH 2 -) n -R 1A polymer, wherein R and R1 are each independently one of H, alkyl, aryl, heterocyclic group, alkyl containing O, N, P, or S elements, or aryl containing O, N, P, or S elements, and n ≥ 2.
[0034] Preferably, the molecular formula is R-(-O-CH 2 -CH 2 -) n -R 1 The polymer selected from the group consisting of polyoxyethylene ether polymers, polyoxyethylene phosphate polymers, polyoxyethylene-polyoxypropylene ether polymers, and polyoxyethylene ester polymers is at least one.
[0035] Furthermore, the polyoxyethylene ether polymers include at least one of fatty alcohol polyoxyethylene ether polymers, fatty amine polyoxyethylene ether polymers, oleyl alcohol polyoxyethylene ether polymers, and alkylphenol polyoxyethylene ether polymers.
[0036] Furthermore, the polyoxyethylene phosphate polymers include at least one of fatty alcohol polyoxyethylene phosphate polymers, alkyl polyoxyethylene phosphate polymers, and aryl polyoxyethylene phosphate polymers.
[0037] Furthermore, the polyoxyethylene-polyoxypropylene ether polymers include at least one of EO-PO block polymer types and EO-PO-EO block polymer types.
[0038] Furthermore, the polyoxyethylene ester polymers include at least one of fatty acid polyoxyethylene esters and aromatic acid polyoxyethylene esters.
[0039] Preferably, the polymer with the molecular formula R-(-O-CH 2 -CH 2 -) n -R 1 is selected from at least one of triphenylstyrene phenol polyoxyethylene ether and octadecylamine polyoxyethylene ether; more preferably triphenylstyrene phenol polyoxyethylene ether.
[0040] Preferably, the polymer with the molecular formula R-(-O-CH 2 -CH 2 -) n -R 1 has a concentration of 0.001 - 0.004 wt%.
[0041] The polymer can adsorb on the surface of the silicon wafer and change the properties of the silicon wafer surface through its own structural features such as amide groups and other polymers. In particular, polyvinylpyrrolidone contains polar groups and can interact with some active sites on the silicon surface to form a relatively stable adsorption layer. At the same time, polyvinylpyrrolidone can adsorb on the surface of silica sol. Through mechanisms such as steric hindrance, it can prevent the aggregation and precipitation of silica sol, ensuring that they can be evenly and stably dispersed in the polishing liquid. During the polishing process of the entire silicon wafer surface, the abrasive particles can uniformly exert a grinding effect, making the polishing effect more uniform and consistent, which helps to improve the flatness and surface quality of the silicon wafer.
[0042] Furthermore, triphenylstyryl phenol polyoxyethylene ether cooperates with complexing agents, N-methylpiperazine, polymers, etc. in the polishing liquid, weakening the steric effect between surfactant molecules, facilitating the formation of micelles, increasing the surface tension, so that the system is in a low-foam or foam-free state. At the same time, it can make the polishing process proceed more smoothly and orderly, avoiding the situation of too fast or too slow local polishing rate, which helps to accurately control the polishing effect and obtain parameters such as the required surface roughness.
[0043] The second aspect of the present invention provides a preparation method of the polishing liquid, including the following steps: adding the polymer into water and stirring well, then adding a complexing agent, a polymer with the molecular formula R-(-O-CH 2 -CH 2 -)n-R 1 , a nitrogen-containing substance, and finally adding silica sol, and stirring evenly to obtain the polishing liquid.
[0044] Beneficial effects:
[0045] This application uses 0.5 - 2 wt% of nitrogen-containing substances; 0.01 - 0.1 wt% of polymers; 0.001 - 0.004 wt% of R-(-O-CH 2 -CH 2 -) n -R 1 as the key components of the polishing liquid, which can make the polishing liquid have a higher polishing rate. Moreover, on the premise of not containing a defoaming agent, the system is in a low-foam or foam-free state, effectively reducing the influence of foam on polishing, making the silicon wafer surface super-hydrophilic, effectively reducing particle residues, and protecting the silicon wafer from corrosion during the polishing process; in particular, the nitrogen-containing substance is N-methylpiperazine, the polymer is polyvinylpyrrolidone or polyvinyl alcohol, and R-(-O-CH 2 -CH 2 -) n -R 1When it is triphenylstyrene phenol polyoxyethylene ether, the contact angle between the silicon wafer and water is 18 - 19°, there are no corrosion pits, and the roughness ≤ 0.25 nm. Detailed implementation mode
[0046] The present invention will be specifically described below through examples.
[0047] Unless otherwise specified, the raw materials used are commercially available.
[0048] In this application, polyvinylpyrrolidone is PVP10:
[0049] The model of triphenylstyrene phenol polyoxyethylene ether is 600 - 3, purchased from Hai'an Petrochemical.
[0050] Table 1 Components of the polishing liquid in Examples 1 - 3
[0051]
[0052] Table 2 Components of the polishing liquid in Examples 4 - 5
[0053]
[0054]
[0055] Table 3 Components of the polishing liquid in Examples 7 - 9
[0056]
[0057] Table 4 Components of the polishing liquid in Example 10
[0058]
[0059]
[0060] Performance test
[0061] (1) Contact angle test: After the silicon wafer is polished, use H 2 O 2 : NH 3 .H 2 O: H 2 O = 1:2:80, ultrasonically clean for 10 - 20 min at 60 - 70 °C, take out and dry, and test the contact angle between the polished surface and ultrapure water.
[0062] (2) Static corrosion test: Place the silicon wafer in the polishing liquid (diluted 1:40 with water), place it at 50 - 80 °C for 2 - 3 h, take out and dry, and test and count the average diameter of the corrosion pits on the silicon wafer surface under a metallurgical microscope.
[0063] (3) Removal rate test: Conduct a polishing test in the following process
[0064] Pressure: 300 g / cm 2
[0065] Rotation speed: 30 rpm
[0066] Flow rate: 250 ml / min
[0067] Dilution ratio: Dilute with water at 1:40
[0068] Weigh the mass before and after polishing respectively, and use the following formula to calculate the removal rate, that is, MRR (nm / min):
[0069]
[0070] Δm is the mass difference of the silicon wafer before and after polishing; ρ is the density of the silicon wafer; S is the surface area of the silicon wafer; T is the polishing time
[0071] (4) Roughness test:
[0072] After the silicon wafer is polished, use H 2 O 2 :NH 3 .H 2 O:H 2 O = 1:2:80, ultrasonically clean for 10 - 20 min at 60 - 70 °C, take out and dry, and use AFM to test the surface roughness.
[0073] (5) Foam height test:
[0074] Method: Dilute the polishing liquid 1:40 with water, fill it into the bubbler, turn on the bubbler, stop after 1 min, and record the foam height.
[0075]
[0076] It can be seen from Examples 1 - 3 that using 0.5 - 2 wt% of N - methylpiperazine; 0.01 - 0.1 wt% of polyvinylpyrrolidone; 0.001 - 0.004 wt% of triphenylethylphenol polyoxyethylene ether as the key components of the polishing liquid can make the polishing liquid have a high polishing rate, and on the premise of not containing a defoaming agent, the foam height is zero, effectively reducing the influence of foam on polishing, making the contact angle between the polished silicon wafer and water be 18 - 19°, and there are no corrosion pits, and the roughness ≤ 0.25 nm.
[0077] It can be seen from Example 1 and Examples 4 - 5 that when triphenylethylphenol polyoxyethylene ether is replaced by nonylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether; although a high polishing rate and a super - hydrophilic surface can be maintained, there is a certain amount of foam, which will cause certain corrosion to the silicon wafer, and the roughness increases.
[0078] It can be seen from Example 1 and Example 6 that when the content of triphenylstyrene phenol polyoxyethylene ether is relatively high, the polishing rate of the silicon wafer will be greatly reduced, and the roughness of the silicon wafer will also be affected to a certain extent.
[0079] It can be seen from Example 1 and Example 7 that when the content of triphenylstyrene phenol polyoxyethylene ether is relatively low, a small amount of foam will appear, causing 25-nm corrosion pits on the silicon wafer, and the roughness reaches 0.52 nm.
[0080] It can be seen from Example 1, Example 8, Example 9, and Example 10 that when N-methylpiperazine is replaced by hydroxyethyl ethylenediamine, the polishing rate of the silicon wafer is lower than 600 nm / min; when the polymer is hydroxyethyl cellulose, not only the polishing rate decreases, but also the hydrophilicity of the silicon wafer surface becomes worse; when the polymer is a PVA-PVP copolymer, the effect is close to that of polyvinylpyrrolidone.
[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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 silicon wafer polishing liquid for chemical mechanical polishing, characterized in that: Includes the following components: Silica sol: 5-20wt%; Complexing agent: 0-1wt%, excluding 0wt%; Nitrogen-containing substances: 0.5-2wt%; High molecular weight polymer: 0.01-0.1wt%; The molecular formula is R-(-O-CH2-CH2-) n -Polymer of R1: 0.001-0.1 wt%; Water: Balance.
2. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 1, characterized in that: The silica sol has an average primary particle size of 1-100 nm and an average secondary particle size of 1-200 nm.
3. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 2, characterized in that: The silica sol has an average primary particle size of 20-50 nm and an average secondary particle size of 50-100 nm.
4. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 1, characterized in that: The complexing agent is selected from one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, N-hydroxyethylethylaminetriacetic acid, ethylene glycol-bis-(B-aminoethyl ether)-N,N-tetraacetic acid, hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, triethylenetetraaminehexamethylenephosphonic acid, bis(1,6-hexylene)triaminepentamethylenephosphonic acid, and polyaminopolyethertetramethylenephosphonic acid.
5. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 1, characterized in that: The nitrogen-containing substance is selected from at least one of hydroxylamine-containing compounds, non-hydroxylamine-containing compounds, and heterocyclic nitrogen-containing compounds.
6. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 5, characterized in that: The heterocyclic nitrogen-containing compounds include one or more of piperazine and its derivatives, imidazole and its derivatives, pyrazine and its derivatives, oxazoline and its derivatives, quinoline and its derivatives, and pyridine and its derivatives.
7. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 6, characterized in that: The nitrogen-containing substance is selected from hydroxyethylethylenediamine and / or N-methylpiperazine.
8. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 1, characterized in that: The high molecular polymer includes at least one of cellulose and its derivatives, amide-containing polymers, and polyvinyl alcohol.
9. The silicon wafer polishing liquid for chemical mechanical polishing according to claim 8, characterized in that: The cellulose and its derivatives include at least one of cellulose, hydroxyethyl cellulose and hydroxymethyl cellulose.
10. A method for preparing a silicon wafer polishing liquid for chemical mechanical polishing according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: adding a high molecular polymer into water and stirring the mixture thoroughly, then adding a complexing agent, a polymer with a molecular formula of R-(-O-CH2-CH2-)n-R1, and a nitrogen-containing substance, and finally adding silica sol and stirring the mixture uniformly to obtain a polishing liquid.