Polishing composition
By using polyhydroxy alcohol as a co-solvent in the polishing composition, the winding of the surfactant and the abrasive particles is suppressed, and the abrasive particles aggregation problem caused by the increase in temperature is solved, and the polishing performance is improved.
Patent Information
- Application Number
- CN202310855569.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-12
- Publication Date
- 2025-01-14
AI Technical Summary
During the chemical mechanical polishing process, due to the increase in temperature, the molecular bond vibration of the surfactant is strengthened, which weakens the hydrogen bonding effect, resulting in the reduction of the solubility of the surfactant, precipitation and wrapping of abrasive particles, causing aggregation of abrasive particles and affecting the polishing performance.
The cosolvent polyhydroxy alcohol is added to the polishing composition, and the interaction with the nonionic surfactant through its multi-hydrogen bond site is inhibited from winding the abrasive particles by the long-chain molecular structure of the surfactant and reducing abrasive particles agglomeration.
The damage to the silicon wafer substrate by abrasive aggregation is effectively avoided, and the polishing performance of the polishing composition is improved, especially when the temperature rises, the abrasive particles are maintained in a good state of dispersion.
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Figure CN119307183A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of chemical mechanical polishing, and in particular to a polishing composition. Background Art
[0002] Chemical mechanical polishing (CMP) is a widely used semiconductor flattening technology and is essential in the production of single crystal silicon. CMP of silicon wafers achieves high-quality flat surfaces through alternating and cyclic chemical corrosion of the polishing composition (polishing liquid) and mechanical wear of the abrasive particles and polishing pads.
[0003] In the related art, the polishing composition is composed of abrasive particles, surfactants and water. However, since heat is generated during the polishing process, the temperature of the polishing liquid will rise. Among them, the temperature rise will strengthen the molecular bond vibration of the surfactant in the polishing liquid and weaken the hydrogen bonding effect, resulting in reduced solubility of the surfactant and precipitation. The polymer long chain structure of the precipitated surfactant entangles the abrasive particles, causing the abrasive particles to aggregate, causing scratches on the surface of the silicon wafer, and affecting the polishing performance of the polishing agent. Summary of the invention
[0004] The embodiment of the present application provides a polishing composition, which can reduce the precipitation of surfactant in the polishing composition when the temperature rises during the polishing process, thereby avoiding agglomeration of abrasive particles in the polishing composition, thereby improving the polishing performance of the polishing composition.
[0005] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:
[0006] The embodiment of the present application provides a polishing composition, the components of which include: abrasive particles, a surfactant, a cosolvent and a solvent. Among them, the surfactant is a non-ionic surfactant, and the cosolvent is a polyhydric alcohol. The polishing composition provided by the present application can, by adding a cosolvent polyhydric alcohol to the polishing composition, be able to, during the process of polishing using the polishing composition, under the action of mechanical friction and chemical reaction, when the temperature of the silicon wafer substrate rises, due to the multiple hydroxyl groups contained in the polyhydric alcohol and the structure of the multiple hydrogen bonding sites provided by the multiple hydroxyl groups, interact with the non-ionic surfactant in the polishing composition, and inhibit the long-chain molecular structure of the non-ionic surfactant from entangled with the abrasive particles, reduce the agglomeration of the abrasive particles in the polishing composition, and then avoid the agglomerated abrasive particles from causing damage to the silicon wafer substrate, thereby improving the polishing performance of the polishing composition.
[0007] Optionally, in the polishing composition, the content of abrasive particles is 0.001-1wt%; the content of surfactant is 0.001-0.02wt%; and the content of cosolvent is 0.001-5wt%. The above is the preferred range of the content of each component included in the polishing composition provided by the present application. When the content of each component included in the polishing composition is within the preferred range, the surfactant can provide a buffer for the contact between the abrasive particles and the silicon wafer substrate. The structure of the multi-hydrogen bond site provided by the cosolvent can interact with the non-ionic surfactant in the polishing composition, inhibit the long-chain molecular structure of the non-ionic surfactant from entangled with the abrasive particles, reduce the agglomeration of abrasive particles in the polishing composition, and thus avoid the damage of the agglomerated abrasive particles to the silicon wafer substrate, so the polishing composition has good polishing performance.
[0008] Optionally, at 20° C., the polydispersity index of the abrasive particles in the polishing composition is less than 0.2, and at 40° C., the polydispersity index of the polishing composition is less than 0.13. Since the polydispersity index reflects the particle size of the abrasive particles in the polishing composition, that is, reflects the agglomeration of the abrasive particles in the polishing composition. Therefore, the abrasive particles in the polishing composition provided by the present application are less agglomerated, and the agglomerated abrasive particles can be prevented from causing damage to the silicon wafer substrate.
[0009] Optionally, the ratio of the polydispersity index of the polishing composition at 20°C to the polydispersity index of the polishing composition at 40°C is greater than 1. Since the ratio of the polydispersity index of the polishing composition at 20°C to the polydispersity index of the polishing composition at 40°C is greater than 1, the polydispersity index of the polishing composition at 20°C is greater than the polydispersity index of the polishing composition at 40°C. Therefore, when the temperature of the polishing composition is increased, the abrasive particles in the polishing composition are not agglomerated, thereby preventing the agglomerated abrasive particles from damaging the silicon wafer substrate.
[0010] Optionally, the nonionic surfactant is one or more of hydroxyethyl cellulose, polydimethylsiloxane, dimethylpolysiloxane polyether copolymer, polyoxyethylene (9) lauryl alcohol ether, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyoxypropylene polyoxyethylene block copolymer, polyacrylamide, cellulose derivatives or starch derivatives. The polishing composition provided by the present application can reduce the precipitation of multiple nonionic surfactants when the temperature of the polishing composition is increased by adding a cosolvent, thereby reducing agglomeration of abrasive particles. Since it is compatible with multiple nonionic surfactants, it can meet the user's usage needs in different usage scenarios.
[0011] Optionally, the polyhydric alcohol is one or more of methanol, ethanol, ethylene glycol, propanol, propylene glycol, and glycerol. The polishing composition provided in the present application may be added with various types of co-solvents, thereby being able to meet the needs of users in different usage scenarios.
[0012] Optionally, the pH of the polishing composition is greater than or equal to 9 and less than or equal to 12. The above is the preferred range of pH of the polishing composition provided in the present application. When the pH of the polishing composition is within the preferred range, the polishing composition has good polishing performance.
[0013] Optionally, the electrical conductivity of the polishing composition is less than or equal to 750 us / cm. The above is the preferred range of the electrical conductivity of the polishing composition provided in the present application. When the electrical conductivity of the polishing composition is within the preferred range, the polishing composition has good polishing performance.
[0014] Optionally, the abrasive particles include one or more of aluminum oxide, pyrogenic silica, colloidal silica, titanium oxide, cerium oxide, and zirconium oxide. The polishing composition provided in the present application may contain a variety of abrasive particles, thereby meeting the needs of users in different usage scenarios.
[0015] Optionally, the particle size of the abrasive particles is 30 to 120 nm. The above is the preferred range of the particle size of the abrasive particles of the polishing composition provided by the present application. When the particle size of the abrasive particles of the polishing composition is within the preferred range, the polishing composition has good polishing performance.
[0016] The polishing composition comprises abrasive grains, a surfactant, a cosolvent and water. The polishing composition is prepared by mixing and dispersing, wherein the method of dispersing and dissolving the components of the polishing composition in water is arbitrary, and the order of dispersing the components in water is also arbitrary. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 A schematic diagram of a polishing process of a polishing composition;
[0018] Figure 2 A schematic diagram of a polishing process of another polishing composition;
[0019] Figure 3 This is a schematic diagram of the polishing process of a polishing composition shown in an embodiment of the present application. DETAILED DESCRIPTION
[0020] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Among them, in the description of the present application, unless otherwise specified, " / " indicates that the objects associated before and after are in an "or" relationship, for example, A / B can represent A or B; "and / or" in the present application is only a kind of association relationship describing the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. And, in the description of the present application, unless otherwise specified, "multiple" refers to two or more than two. "At least one of the following" or its similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.
[0021] Chemical mechanical polishing (CMP) is a widely used semiconductor flattening technology and is essential in the production and manufacturing of single crystal silicon. The CMP of silicon wafers is carried out alternately and cyclically through the chemical corrosion of the polishing composition (polishing liquid) and the mechanical wear of the abrasive particles and polishing pads to achieve a high-quality flat surface. Fine polishing is the last step in the polishing of silicon wafers, and the results are directly related to the yield, performance and reliability of the device. Moreover, as the chip manufacturing technology node decreases, the control requirements for the flatness, defects and cleanliness of the wafer surface are also more stringent. Therefore, fine polishing of silicon wafers has become increasingly important in the manufacturing process of single crystal silicon.
[0022] Common surface defects in the process of silicon wafer fine polishing include surface micro scratches, pits, polishing haze and residual particles, etc. Polishing fluids with different compositions can have different effects on the polishing surface accuracy.
[0023] In the related art, see Figure 1 , Figure 1 The figure is a schematic diagram of the polishing process of a polishing composition. The polishing composition is composed of abrasive particles (hereinafter referred to as abrasive particles), a surfactant and a solvent. The surfactant is used to form a buffer layer between the abrasive particles and the silicon wafer to prevent the abrasive particles from directly contacting the silicon wafer, thereby causing scratches, pits and other defects on the wafer surface. However, since CMP is based on chemical energy and mechanical energy, heat is generated during the polishing process, which causes the temperature of the polishing liquid to rise. Figure 2 , Figure 2This is a schematic diagram of the polishing process of another polishing composition. The temperature rise will strengthen the molecular bond vibration of the surfactant in the polishing liquid and weaken the hydrogen bonding effect, resulting in a decrease in the solubility of the surfactant and precipitation from the solvent. The high molecular long chain structure of the precipitated surfactant will entangle the abrasive particles, thereby causing the abrasive particles to aggregate, resulting in the aggregated abrasive particles causing scratches on the silicon wafer surface, affecting the polishing performance of the polishing agent.
[0024] In view of this, an embodiment of the present application provides a polishing composition, the components of which include abrasive particles, a surfactant, a cosolvent and a solvent. Among them, the surfactant is a non-ionic surfactant, and the cosolvent is a polyhydric alcohol. The polishing composition provided by the present application can, by adding a cosolvent polyhydric alcohol to the polishing composition, be able to use the polishing composition for polishing. Under the action of mechanical friction and chemical reaction, when the temperature of the silicon wafer substrate rises, due to the multiple hydroxyl groups contained on the polyhydric alcohol and the structure of the multiple hydrogen bonding sites provided by the multiple hydroxyl groups, it can interact with the non-ionic surfactant in the polishing composition, and can inhibit the long-chain molecular structure of the non-ionic surfactant from entangled with the abrasive particles, reduce the agglomeration of the abrasive particles in the polishing composition, and then avoid the agglomerated abrasive particles from causing damage to the silicon wafer substrate, thereby improving the polishing performance of the polishing composition.
[0025] The polishing compositions of the embodiments and comparative examples are shown in Tables 1 and 2.
[0026] It should be understood that the polishing composition comprises abrasive particles, a surfactant, a cosolvent and a solvent. The polishing composition is prepared by mixing and dispersing, wherein the method of dispersing and dissolving the components of the polishing composition in the solvent is arbitrary, and the order of dispersing the components in the solvent is also arbitrary.
[0027] In one example, the solvent is deionized water. It should be understood that the solvent may also be other solvents capable of dissolving surfactants, and the specific implementation of the solvent is not particularly limited in the embodiment of the present application.
[0028] Optionally, the abrasive particles, surfactants, co-solvents and solvents provided in the embodiments of the present application are self-prepared or purchased from outside, and the embodiments of the present application do not impose any particular restrictions on the sources of the abrasive particles, surfactants, co-solvents and solvents.
[0029] Specifically, the types, particle sizes and contents of the abrasive particles included in Comparative Examples 1-15 and Examples 1-4 are exactly the same.
[0030] The content of the abrasive particles is 0.001-1 wt %, and the types of the abrasive particles include one or more of aluminum oxide, pyrogenic silicon dioxide, colloidal silicon dioxide, titanium oxide, cerium oxide, and zirconium oxide. The particle size of the abrasive particles is 30-120 nm.
[0031] As shown in Table 1, no surfactant was added in Comparative Example 1, and the surfactants added in Comparative Examples 2-15 and Examples 1-4 were hydroxyethyl cellulose and polyoxyethylene-polyoxypropylene-polyoxyethylene. Among them, the content of hydroxyethyl cellulose was 0.008%, and the content of polyoxyethylene-polyoxypropylene-polyoxyethylene was 0.0015%. Among them, the molecular weight of the hydroxyethyl cellulose added in Comparative Examples 3 and 4 was 720,000, and the molecular weight of the hydroxyethyl cellulose added in Comparative Examples 5 and 6 was 1.3 million. The cellulose added in the remaining Comparative Examples and Examples 1-4 was 90,000.
[0032] It should be understood that the surfactant used in the embodiments of the present application may also be any other type of nonionic surfactant. For example, the nonionic surfactant is one or more of hydroxyethyl cellulose, polydimethylsiloxane, dimethylpolysiloxane polyether copolymer, polyoxyethylene (9) lauryl alcohol ether, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyoxypropylene polyoxyethylene block copolymer, polyacrylamide, cellulose derivatives or starch derivatives.
[0033] The cellulose derivative may be methyl cellulose, carboxymethyl cellulose, ethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose or hydroxypropyl methyl cellulose.
[0034] As shown in Table 1, no co-solvent was added in Comparative Examples 2, 3 and 5, and the co-solvent added in other Comparative Examples and Examples 1-4 except Comparative Examples 2, 3 and 5 was propylene glycol.
[0035] Optionally, the co-solvent provided in the embodiments of the present application may also be other polyhydric alcohols, for example, one or more of methanol, ethanol, ethylene glycol, propanol, propylene glycol, and glycerol.
[0036] It should be understood that the co-solvent provided in the embodiments of the present application may also be other substances having a polyhydroxy structure, and the embodiments of the present application do not impose any particular limitation on this.
[0037] Referring to Table 2, the Examples of the present application used ammonia water and nitric acid to adjust the pH values and conductivity of Comparative Examples 1-15 and Examples 1-4.
[0038] The present application example evaluates the abrasive agglomeration degree of each polishing composition at different temperatures by detecting the polydispersity index (PDI) of each comparative example and example polishing composition at different temperatures. Referring to Table 2, the present application example detects the polydispersity index of the polishing composition at 20°C and 40°C.
[0039] In the present application, the filtration performance of the polishing composition of each embodiment and comparative example is evaluated by a capsule filter. The rated filtration accuracy is 0.5 μm. When the volume of the polishing composition passing through the capsule filter is greater than 500 mL, the filtration performance of the polishing composition is determined to be good (okay, OK), and when the volume of the polishing composition passing through the capsule filter is less than or equal to 500 mL, the filtration performance of the polishing composition is determined to be bad (no good, NG).
[0040] In the present application, the surface of the silicon wafer treated by the polishing composition of each embodiment and comparative example is detected by a patternless wafer defect detector to obtain the number of defects and haze on the surface of the treated silicon wafer to evaluate the polishing performance of the polishing composition of each embodiment and comparative example. Wherein, when the number of defects on the surface of the treated silicon wafer is less than or equal to 200, the defect handling performance of the polishing performance of the polishing composition is determined to be OK. When the number of defects on the surface of the treated silicon wafer is greater than 200, the defect handling performance of the polishing composition is determined to be NG.
[0041] When the haze of the treated silicon wafer surface is less than or equal to 0.1 ppm, the haze treatment performance of the polishing performance of the polishing composition is determined to be OK. When the haze of the treated silicon wafer surface is greater than 0.1 ppm and less than 0.15 ppm, the haze treatment performance of the polishing composition is determined to be NG.
[0042] Combining Table 1 and Table 2, it can be seen from Comparative Examples 1-15 and Examples 1-4 that the polydispersity index of the polishing composition at 20°C affects the filtration performance of the polishing composition, and the polydispersity index of the polishing composition at 40°C affects the polishing performance of the polishing composition. The preferred range of the polydispersity index of the polishing composition is that at 20°C, the polydispersity index is less than 0.2. At 40°C, the polydispersity index is less than 0.13.
[0043] Combining Table 1 and Table 2, it can be seen from Comparative Examples 1-15 and Examples 1-4 that the ratio of the polydispersity index of the polishing composition at 20°C to the polydispersity index of the polishing composition at 40°C affects the filtration performance and polishing performance of the polishing composition. The preferred range of the above ratio is greater than 1.
[0044] Combined with Table 1, it can be seen from Comparative Example 1 and Example 1 that adding a surfactant to the polishing composition can improve the polishing performance of the polishing composition, reduce the number of defects on the surface of the silicon wafer, and reduce the haze of the surface of the silicon wafer.
[0045] In combination with Table 1, it can be seen from Comparative Example 2 and Example 1, Comparative Example 3 and Comparative Example 4, Comparative Example 5 and Comparative Example 6 that adding glycerol to the polishing composition can reduce the polydispersity index of the polishing composition at 40°C, that is, reduce the agglomeration of the abrasive particles of the polishing composition at 40°C, thereby improving the polishing performance of the polishing composition and reducing the number of defects on the surface of the silicon wafer.
[0046] Combined with Table 1, it can be seen from Comparative Examples 7 and 8 and Example 2 that different contents of surfactants can affect the polishing performance of the polishing composition, and the preferred range of the content of the surfactant in the polishing composition is less than or equal to 0.002%.
[0047] In combination with Table 2, it can be seen from Comparative Examples 9, 10, 11, 12, Examples 1 and 3 that the pH value of the polishing composition can affect the polydispersity index of the polishing composition at 20°C and 40°C, thereby affecting the defect treatment performance and haze treatment performance of the polishing composition, and the preferred range of the pH value of the polishing composition is greater than or equal to 9 and less than or equal to 12.
[0048] Combined with Table 2, it can be seen from Comparative Examples 13, 14, Examples 1, 4 and 5 that the conductivity of the polishing composition affects the haze treatment performance of the polishing composition, and the preferred range of the conductivity of the polishing composition is 750 us / cm.
[0049] To understand this solution, see Figure 3 , Figure 3 A schematic diagram of the polishing process of a polishing composition shown in an embodiment of the present application, when the temperature of the silicon wafer substrate rises under the action of mechanical friction and chemical reaction, due to the multiple hydroxyl groups contained in the co-solvent polyhydroxy alcohol in the polishing composition, the structure of the multiple hydrogen bonding sites provided by the multiple hydroxyl groups can interact with the surfactant, inhibiting the long-chain molecular structure of the surfactant from entangled with the abrasive particles, reducing the agglomeration of the abrasive particles in the polishing composition, that is, reducing the polydispersity index of the polishing composition when the temperature rises, thereby avoiding damage to the silicon wafer substrate caused by the agglomerated abrasive particles, thereby improving the polishing performance of the polishing composition.
[0050] Table 1
[0051]
[0052] Table 2
[0053]
[0054]
Claims
1. A polishing composition, characterized in that The components of the polishing composition include: Abrasive particles; Surfactants; Solvent; Solvents; Wherein, the surfactant is a nonionic surfactant, and the cosolvent is a polyhydric alcohol.
2. The polishing composition according to claim 1, characterized in that In the polishing composition, the content of the abrasive grains is 0.001 to 1 wt %; the content of the surfactant is 0.001 to 0.02 wt %; and the content of the co-solvent is 0.001 to 5 wt %.
3. The polishing composition according to claim 1 or 2, characterized in that At 20° C., the polydispersity index of the abrasive particles in the polishing composition is less than 0.2, and at 40° C., the polydispersity index of the polishing composition is less than 0.
13.
4. The polishing composition according to any one of claims 1 to 3, characterized in that The ratio of the polydispersity index of the polishing composition at 20° C. to the polydispersity index of the polishing composition at 40° C. is greater than 1.
5. The polishing composition according to any one of claims 1 to 4, characterized in that The nonionic surfactant is one or more of hydroxyethyl cellulose, polydimethylsiloxane, dimethylpolysiloxane polyether copolymer, polyoxyethylene (9) lauryl alcohol ether, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyoxypropylene polyoxyethylene block copolymer, polyacrylamide, cellulose derivatives or starch derivatives.
6. The polishing composition according to any one of claims 1 to 5, characterized in that The polyhydric alcohol is one or more of methanol, ethanol, ethylene glycol, propanol, propylene glycol and glycerol.
7. The polishing composition according to any one of claims 1 to 6, characterized in that The pH of the polishing composition is greater than or equal to 9 and less than or equal to 12.
8. The polishing composition according to any one of claims 1 to 7, characterized in that The electrical conductivity of the polishing composition is less than or equal to 750 us / cm.
9. The polishing composition according to any one of claims 1 to 8, characterized in that The abrasive particles include one or more of aluminum oxide, fumed silica, colloidal silica, titanium oxide, cerium oxide, and zirconium oxide.
10. The polishing composition according to any one of claims 1 to 9, characterized in that The particle size of the abrasive particles is 30 to 120 nm.