Applications and chemimechanical polishing fluid of a water-soluble small molecule containing a morpholine ring.

Abstract

This invention discloses the use of a water-soluble small molecule containing a morpholine ring as a raw material component in a chemical mechanical polishing slurry to reduce edge collapse in the silicon wafer edge region. This technical solution can effectively reduce edge collapse at the outer periphery of the silicon wafer without significantly affecting the silicon wafer polishing rate, improving the flatness of the silicon wafer edge region. This satisfies the need for silicon wafer planarization in production while ensuring the quality and performance of subsequent process steps.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor integrated circuit manufacturing, and particularly relates to a chemical mechanical polishing technology for silicon wafers. BACKGROUND

[0002] With the development of integrated circuit industry, advanced process technology has higher requirements for the surface flatness of silicon wafers. Chemical mechanical polishing (CMP) and double-side chemical mechanical polishing (DSP) technologies can achieve high flatness of silicon wafers.

[0003] CMP technology is a combination of chemical and mechanical actions, and has the advantages of fast processing speed, high polishing quality, and reliable processing results. However, in the processing process, the polishing rate of the edge region of the silicon wafer is faster than that of the center region, resulting in the appearance of edge roll-off (ERO) on the outer periphery of the silicon wafer, which adversely affects the quality and performance of subsequent process steps. The CMP process is complex and has many influencing factors, including the type of workpiece surface material, the composition of the polishing liquid, the pressure of the polishing head, and the like.

[0004] Therefore, there is an urgent need for a technical solution that can improve the flatness of silicon wafers and effectively reduce the amount of edge roll-off in the edge region of the silicon wafer. SUMMARY

[0005] In view of the above-mentioned shortcomings of the prior art, the present application aims to provide a chemical mechanical polishing liquid and a preparation method thereof that can improve the flatness of silicon wafers and effectively reduce the amount of edge roll-off in the edge region of the silicon wafer without significantly affecting the polishing rate of the silicon wafer. To achieve the above-mentioned and other related purposes, the present application is obtained by the following technical solutions.

[0006] The present application provides, in a first aspect, the use of a water-soluble small molecule containing a morpholine ring as a raw material component in a chemical mechanical polishing liquid for reducing the amount of edge roll-off in the edge region of a silicon wafer.

[0007] According to the above-mentioned use, the water-soluble small molecule containing a morpholine ring also has one or more of phosphorus oxy, carbonyl, ester, ether, and amide groups.

[0008] According to the above-mentioned use, the water-soluble small molecule containing a morpholine ring includes one or more of 2,2-dimorpholinyl diethyl ether, tris(4-morpholinyl)phosphine oxide, dimorpholinyl ketone, and 4-(2-methoxyethyl)morpholine.

[0009] The amount of the water-soluble small molecule containing a morpholine ring is 0.005-0.5% by weight based on the total mass of the chemical mechanical polishing solution. Preferably, the amount can be 0.005-0.05%, 0.05-0.1%, 0.1-0.2%, 0.2-0.3%, 0.25-0.35%, 0.3-0.4%, 0.4-0.5%, or 0.3% in a specific embodiment.

[0010] The second aspect of the present application provides a chemical mechanical polishing solution, the raw material components of which include a water-soluble small molecule containing a morpholine ring. The polishing solution containing the water-soluble small molecule containing a morpholine ring can effectively reduce the amount of collapse at the periphery of a silicon wafer and improve the flatness of the edge region of the silicon wafer during chemical mechanical polishing of the silicon wafer without significantly affecting the polishing rate.

[0011] The chemical mechanical polishing solution described above further includes: an abrasive; an alkaline compound; and water.

[0012] The amount of the water-soluble small molecule containing a morpholine ring is 0.005-0.5% by weight based on the total mass of the chemical mechanical polishing solution. Preferably, the amount can be 0.005-0.05%, 0.05-0.1%, 0.1-0.2%, 0.2-0.3%, 0.25-0.35%, 0.3-0.4%, 0.4-0.5%, or 0.3% in a specific embodiment.

[0013] The amount of the abrasive is 1-40% by weight based on the total mass of the chemical mechanical polishing solution. Preferably, the amount can be 1-10%, 10-20%, 20-25%, 25-30%, 30-35%, 32-38%, 35-40%, or 35% in a specific embodiment.

[0014] The water-soluble small molecule containing a morpholine ring includes one or more of 2,2-dimorpholinyl diethyl ether, tris(4-morpholinyl)phosphine oxide, dimorpholinomethanone, and 4-(2-methoxyethyl)morpholine.

[0015] The abrasive is selected from one or more of inorganic particles, organic particles, and organic-inorganic composite particles.

[0016] According to the chemical mechanical polishing liquid described above, the inorganic particles include one or more of silica, metal oxide particles, nitride particles, carbide particles, and diamond particles; and the organic particles include one or more of polymethyl methacrylate (PMMA) particles, polyacrylic acid particles, and polyacrylonitrile particles.

[0017] More preferably, the silica is colloidal silica.

[0018] According to the chemical mechanical polishing liquid described above, the metal oxide particles include one or more of cerium oxide, aluminum oxide, and zirconium oxide; the nitride particles include one or more of silicon nitride and boron nitride; and the carbide particles include one or more of silicon carbide and boron carbide.

[0019] According to the chemical mechanical polishing liquid described above, in order to improve the polishing rate performance of the polishing liquid, stabilize the storage of the polishing liquid, and reduce the defects on the wafer surface after polishing as much as possible, preferably, the average primary particle size of the abrasive particles is 20-100 nm. The average primary particle size of the abrasive particles can be 20-45 nm, 45-75 nm, or 75-100 nm; more preferably, 30-80 nm; and particularly preferably, 40-70 nm. For example, if the average primary particle size of the abrasive particles is less than 20 nm, the performance of the polishing rate of the polishing liquid will decrease; and if the average primary particle size of the abrasive particles is greater than 100 nm, it will be unfavorable for the flatness of the wafer surface after polishing and the stability of the storage of the polishing liquid. In a specific embodiment, the average primary particle size of the abrasive particles is 55 nm. The limitation of the average primary particle size of the abrasive particles described above is beneficial to improving the polishing rate performance of the polishing liquid, stabilizing the storage of the polishing liquid, and reducing the defects on the wafer surface after polishing.

[0020] The method for measuring the average primary particle size of the abrasive particles is not particularly specified and can be measured by the BET method. In a specific embodiment, a Flow Sorb II 2300 specific surface area measuring instrument developed by Micromeritics Instrument Corporation is used.

[0021] According to the chemical mechanical polishing liquid described above, in consideration of the improvement of the polishing rate performance of the polishing liquid, the stability of the polishing liquid preservation, and the reduction of the wafer surface defects after polishing as much as possible, the average secondary particle size of the abrasive particles is 40-200 nm. Preferably, the average secondary particle size of the abrasive particles can be 40-70 nm, 70-130 nm, or 130-200 nm; more preferably 50-180 nm, and particularly preferably 60-160 nm. For example, if the average secondary particle size of the abrasive particles is less than 40 nm, the performance of the polishing rate of the polishing liquid will decrease, and if it is greater than 200 nm, it is not conducive to the flatness of the wafer surface after polishing and the stability of the polishing liquid preservation. In a specific embodiment, it is 110 nm. The above limitation of the average secondary particle size of the abrasive particles is conducive to the improvement of the polishing rate performance of the polishing liquid, the stability of the polishing liquid preservation, and the reduction of the wafer surface defects after polishing.

[0022] The method for measuring the average secondary particle size of the abrasive particles is not particularly specified, and can be measured by dynamic light scattering method. In a specific embodiment, a Zetasizer Lab nanoparticle size analyzer developed by Malvern Panalytical is used.

[0023] According to the chemical mechanical polishing liquid described above, the basic compound makes the pH of the chemical mechanical polishing liquid 10-12.

[0024] According to the chemical mechanical polishing liquid described above, the basic compound includes one or more of alkali metal hydroxide, carbonate, bicarbonate, nitrogen-containing organic or inorganic basic compound. Preferably, the basic compound is one or more of ammonia, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, and potassium carbonate.

[0025] According to the chemical mechanical polishing liquid described above, the water includes one or more of deionized water, pure water, ultrapure water, and distilled water, which serves to dissolve and carry other components of the polishing liquid.

[0026] According to the chemical mechanical polishing liquid described above, preferably, the preparation method of the polishing liquid is: first, mix the abrasive slurry, the basic compound, and the water to form a mixed liquid, and adjust the pH of the mixed liquid to 10-12 by means of the basic compound, then add the water-soluble small molecule containing the morpholine ring, and stir to mix uniformly.

[0027] The manufacturing method of the chemical mechanical polishing liquid described above is not particularly limited. The components of the polishing liquid can be mixed by stirring, ultrasonic dispersion, homogenization mixing, etc. The mixing method of these components is not particularly limited, and all the components can be mixed at one time, or they can be mixed in a set order.

[0028] The third aspect of the present application provides an application of the chemical mechanical polishing solution as described above in polishing of silicon wafer.

[0029] Preferably, the diameter of the silicon wafer is 200-300 mm.

[0030] Preferably, the polishing pressure is 2-5 psi.

[0031] Preferably, the rotation speed ratio of the polishing head to the polishing pad is 110-140 rpm: 100-130 rpm.

[0032] Preferably, the flow rate of the polishing solution is 150-300 mL / min.

[0033] Preferably, the polishing time is 50-70 s.

[0034] As described above, the present application provides an application of a water-soluble small molecule containing a morpholine ring in a chemical mechanical polishing solution for reducing the amount of edge collapse of a silicon wafer, and also provides a chemical mechanical polishing solution containing a water-soluble small molecule containing a morpholine ring, a preparation method and an application thereof. The technical solution of the present application has the following beneficial effects: the technical solution of the present application can effectively reduce the amount of edge collapse of the periphery of a silicon wafer without significantly affecting the polishing rate of the silicon wafer, and improve the flatness of the edge region of the silicon wafer. This not only meets the needs of silicon wafer planarization in production, but also ensures the quality and performance of subsequent process steps. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A chemical structural formula diagram of 2,2-dimorpholinyl diethyl ether in Example 1 of the present application is shown.

[0036] Figure 2 A chemical structural formula diagram of tris(4-morpholinyl) phosphine oxide in Example 2 of the present application is shown.

[0037] Figure 3 A chemical structural formula diagram of dimorpholinyl ketone in Example 3 of the present application is shown.

[0038] Figure 4 A chemical structural formula diagram of 4-(2-methoxyethyl) morpholine in Example 4 of the present application is shown.

[0039] Figure 5 A chemical structural formula diagram of heptaethylene glycol in Comparative Example 2 of the present application is shown.

[0040] Figure 6 A chemical structural formula diagram of hydroxyethylidene diphosphonic acid in Comparative Example 3 of the present application is shown.

[0041] Figure 7 A chemical structural formula diagram of choline phosphate in Comparative Example 4 of the present application is shown.

[0042] Figure 8 The chemical structure of polyvinylpyrrolidone used in Comparative Example 5 of the present application is shown in the following figure.

[0043] Figure 9 The chemical structure of poly-N-vinylacetamide used in Comparative Example 6 of the present application is shown in the following figure. DETAILED DESCRIPTION

[0044] The present application will now be described by way of specific examples, which serve to demonstrate the practical applicability of the method of the present application. Other advantages and benefits of the present application will become apparent to those skilled in the art from the following description. The present application can also be carried out in other different embodiments and be applied in other different ways. Various modifications and changes in the details thereof can be made without departing from the spirit of the application.

[0045] It should be understood that the process equipment or apparatus not specifically mentioned in the following examples are conventional equipment or apparatus used in the art. Furthermore, it should be understood that the scope of the present application is not limited to the specific embodiments described below, and that one or more of the method steps mentioned in the present application do not exclude the presence of other method steps before and after the mentioned combination of steps, or the insertion of other method steps between the explicitly mentioned steps, unless otherwise specified. It should also be understood that the terms used in the examples of the present application are used to describe the specific embodiments and are not intended to limit the scope of the present application. The test methods in the following examples, for which no specific conditions are mentioned, are generally carried out under conventional conditions, or under the conditions recommended by the respective manufacturers.

[0046] In the following examples of the present application, a specific polishing process condition is used, which is as follows:

[0047] Polishing object: 300 mm diameter (100) surface silicon wafer

[0048] Polishing equipment: Tianjin Huaqiao Universal-300X

[0049] Polishing pad: polyurethane polishing pad SPM-3100 manufactured by NITTA DuPont, Japan

[0050] The rotation speed ratio of the polishing head and the polishing pad is: 123 rpm: 119 rpm

[0051] Polishing liquid flow rate: 300 mL / min

[0052] Polishing pressure: 3.0 psi

[0053] Polishing time: 60 s.

[0054] Example 1

[0055] In this embodiment, a preparation method of a novel chemical mechanical polishing liquid is provided, comprising the following steps:

[0056] 1) 35% by mass of colloidal silica (average primary particle size of 55 nm, average secondary particle size of 110 nm), 1.6% by mass of tetramethylammonium hydroxide (TMAH), 1% by mass of potassium carbonate, and 62.1% by mass of deionized water are uniformly mixed, and the pH is adjusted to 11.5 by means of tetramethylammonium hydroxide (TMAH) and potassium carbonate, based on the total mass of the chemical mechanical polishing liquid;

[0057] 2) 0.3% by mass of 2,2-dimorpholinyl diethyl ether is further added, and the mixture is uniformly stirred at room temperature (25°C) for 30 minutes, to obtain the chemical mechanical polishing liquid.

[0058] The chemical mechanical polishing liquid obtained by the above process is used by adding ion exchange water in a mass ratio of 30 times dilution, to obtain a polishing liquid for use in polishing.

[0059] Example 2

[0060] In this embodiment, a preparation method of a novel chemical mechanical polishing liquid is provided, comprising the following steps:

[0061] Tris(4-morpholinyl)phosphine oxide is used instead of 2,2-dimorpholinyl diethyl ether in Example 1, and the rest is completely the same as Example 1.

[0062] Example 3

[0063] In this embodiment, a preparation method of a novel chemical mechanical polishing liquid is provided, comprising the following steps:

[0064] Dimorpholinomethanone is used instead of 2,2-dimorpholinyl diethyl ether in Example 1, and the rest is completely the same as Example 1.

[0065] Example 4

[0066] In this embodiment, a preparation method of a novel chemical mechanical polishing liquid is provided, comprising the following steps:

[0067] 4-(2-methoxyethyl)morpholine is used instead of 2,2-dimorpholinyl diethyl ether in Example 1, and the rest is completely the same as Example 1.

[0068] Comparative Example 1

[0069] The difference between this comparative example and Example 1 is that no water-soluble small molecule containing a morpholine ring, i.e., no 2,2-dimorpholinyl diethyl ether, is used, and the rest is completely the same as Example 1.

[0070] Comparative Example 2

[0071] This comparative example differs from Example 1 in that heptaglycelol is used instead of 2,2-dimorpholinodiethylether in Example 1; the rest is exactly the same as Example 1.

[0072] Comparative Example 3

[0073] This comparative example differs from Example 1 in that hydroxyethyldiphosphonic acid is used instead of 2,2-dimorpholinodiethylether in Example 1; the rest is exactly the same as Example 1.

[0074] Comparative Example 4

[0075] This comparative example differs from Example 1 in that choline phosphate is used instead of 2,2-dimorpholinodiethylether in Example 1; the rest is exactly the same as Example 1.

[0076] Comparative Example 5

[0077] This comparative example differs from Example 1 in that M W = 2.5 x 10 5 polyvinylpyrrolidone is used instead of 2,2-dimorpholinodiethylether in Example 1; the rest is exactly the same as Example 1.

[0078] Comparative Example 6

[0079] This comparative example differs from Example 1 in that M W = 5 x 10 4 poly-N-vinylacetamide is used instead of 2,2-dimorpholinodiethylether in Example 1; the rest is exactly the same as Example 1.

[0080] The performance of the CMP polishing liquid is generally evaluated by measuring the polishing rate of the silicon wafer and the edge flatness of the silicon wafer after polishing. The polishing rate and the edge flatness of the silicon wafer are measured using a wafer geometry measurement system (WaferSight 2+, KLA Tencor, Milpitas, CA, USA).

[0081] The chemical mechanical polishing liquid obtained in Examples 1 to 4 and Comparative Examples 1 to 6 is subjected to polishing rate detection, and the operation is as follows: the mass of the silicon wafer is measured before and after polishing. The polishing rate is calculated by dividing the mass difference of the silicon wafer before and after polishing by the polishing time.

[0082] The polishing rate detection results are shown in Table 1. The polishing rate of each example in Table 1 is a rate of the polishing rate when the CMP polishing solution of Comparative Example 1 is polished, and the larger the value, the higher the polishing rate. The polishing rate when the CMP polishing solution of Comparative Example 1 is polished is 0.78 μm / min.

[0083] The chemical mechanical polishing solutions obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were subjected to silicon wafer edge flatness detection. The ESFQR was used as an evaluation index of the silicon wafer surface flatness. The ESFQR (Edge flatness metric, Sector based, Front surface referenced, least squares fit reference plane, Range of the data within sector) means that a plurality of points are divided in a sector formed in a 1 mm front region of the silicon wafer edge, and the difference between the highest point and the lowest point of the silicon wafer surface topography with respect to the least squares fit reference plane is measured. ΔESFQR indicates the improvement of the silicon wafer surface flatness before and after polishing, and in the present embodiment, the ΔESFQR of a negative value indicates the improvement of the silicon wafer surface flatness by the CMP polishing solution.

[0084] The silicon wafer edge flatness detection results are shown in Table 1. The ΔESFQR of each example in Table 1 is a rate of the ΔESFQR value when the CMP polishing solution of Comparative Example 1 is polished, and the larger the value, the better the improvement of the silicon wafer edge flatness. The ΔESFQR value when the CMP polishing solution of Comparative Example 1 is polished is -6.5 nm.

[0085] Table 1

[0086]

[0087] Note: The ΔESFQR value when the CMP polishing solution of Comparative Example 1 is polished is -6.5 nm; the polishing rate is 0.78 μm / min.

[0088] From Table 1, it can be seen that the ΔESFQR value of the chemical mechanical polishing liquid obtained by using the preparation method of the present application is much higher than the ΔESFQR value of the polishing liquid obtained in Comparative Examples 1-6, which indicates that the chemical mechanical polishing liquid containing the water-soluble small molecule containing a morpholine ring provided by the present application has a more optimal improvement effect on the edge flatness of a silicon wafer than the chemical mechanical polishing liquid not containing the water-soluble small molecule containing a morpholine ring or the chemical mechanical polishing liquid commercially available in the prior art (Comparative Examples 5 and 6). Meanwhile, the polishing rate of the chemical mechanical polishing liquid obtained by using the preparation method of the present application is basically the same as the polishing rate in the comparative examples, and the above results show that the technical scheme of the present application, i.e., the chemical mechanical polishing liquid containing the water-soluble small molecule containing a morpholine ring, can effectively reduce the amount of edge collapse of a silicon wafer and significantly improve the edge flatness of a silicon wafer without significantly affecting the polishing rate of the silicon wafer.

[0089] The above examples are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. Use of a morpholine ring-containing water-soluble small molecule as a raw material component in a chemical mechanical polishing solution for reducing the amount of edge collapse in a silicon wafer edge region. The morpholine ring-containing water-soluble small molecule includes one or more of 2,2-dimorpholinyl diethyl ether, tris(4-morpholinyl)phosphine oxide, dimorpholinomethanone, and 4-(2-methoxyethyl)morpholine. The raw material components of the chemical mechanical polishing solution further include an abrasive, an alkaline compound, and water. The pH of the chemical mechanical polishing solution is 10 to 12.

2. Use according to claim 1, characterized in that, The amount of the morpholine ring-containing water-soluble small molecule is 0.005 to 0.5 wt% based on the total mass of the chemical mechanical polishing solution.

3. A chemical mechanical polishing liquid characterized by comprising: The raw material components include a morpholine ring-containing water-soluble small molecule; the raw material components further include an abrasive, an alkaline compound, and water. The morpholine ring-containing water-soluble small molecule includes one or more of 2,2-dimorpholinyl diethyl ether, tris(4-morpholinyl)phosphine oxide, dimorpholinomethanone, and 4-(2-methoxyethyl)morpholine. The alkaline compound causes the pH of the chemical mechanical polishing solution to be 10 to 12. The amount of the abrasive is 30 to 40 wt%. The average primary particle diameter of the abrasive is 20 nm to 100 nm. The average secondary particle diameter of the abrasive is 40 nm to 200 nm.

4. The chemical mechanical polishing liquid according to claim 3, wherein The amount of the morpholine ring-containing water-soluble small molecule is 0.005 to 0.5 wt% based on the total mass of the chemical mechanical polishing solution.

5. The chemical mechanical polishing liquid according to claim 3, wherein the abrasive particles are present in an amount of 0.1 to 10 wt%. The alkaline compound includes one or more of an alkali metal hydroxide, a carbonate, a bicarbonate, a nitrogen-containing organic alkaline compound, and a nitrogen-containing inorganic alkaline compound.

6. Use of the chemical mechanical polishing solution according to any one of claims 3 to 5 in polishing of a silicon wafer.

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